DOCTOR OF PHILOSOPHY (Ph.D)
FACULTY OF MEDICINE
“A STUDY OF ANATOMICAL VARIATIONS & ANOMALIES OF CORONARY ARTERIES BY DIFFERENT RADIOLOGICAL TECHNIQUES”
GUIDED BY: Presented By:
DR. M.P.SINGH Dr. Vishnu Pal M.S.(Anatomy) Rtd.
Dean,Proff.& HOD Dept. of Anatomy
Gandhi Medical College, Bhopal (M.P.)
Proff.& HOD, Dept. of Anatomy
Gandhi Medical College ,Bhopal (M.P.)
Gandhi Medical College,Bhopal (M.P.)
“A STUDY OF ANATOMICAL VARIATIONS & ANOMALIES OF CORONARY ARTERIES BY DIFFERENT RADIOLOGICAL TECHNIQUES”
Any task requires a mind and hands working in co-ordination. The hands for this study happened to be mine, but the mastermind behind it belonged to Dr.Asha Dixit (Proff & Head Dept. of Anatomy GMC Bhopal ) and of my guide , Dr.M.P.Singh Rtd. Dean,Proff.& HOD Dept. of Anatomy GMC Bhopal.
It would be futile to express in words, the heart, which is filled with gratitude and respect for them. They have very much helped me overcome every hurdle by their guidance and supervision. Their acuity of vision and perspicacity of thought have made this study a success.
I express sincere gratitude to Dr.G.C.Goutam, Dr.Kamlesh Talresha, Dr.Pankaj Manoria for their valuable presence,guidance and invaluable moral support. With wisdom, earnestness and patience they have motivated and guided me towards excellence during the period of my study.
I would like to acknowledge and thank to Dr.M.Patel ,Dr.V.Sharma Dr.Abhijeet Yadav who have helped me in collecting samples and helped me in various techniques of dissection of the heart. I express my thanks to other teaching and technical staff for their rendered help and support in various ways.
I express my thanks to senior technicians Lab. , Cath lab., and Radiology Mr. Rashid Azam & Mr. Ajay Shrivastava who have helped me in studying angiographies.
Last but not the least, I pay respectful homage to all the departed souls who left behind their mortal remains without which this study would not have been possible.
1. INTRODUCTION : –
Coronary arteries, which supplies myocardium and epicardium these are first branches of aorta .The Right and Left coronary arteries from the corresponding aortic sinuses at proximal part of ascending aorta just superior to aortic valves . The term coronary comes from Letin word “corona” means “crown”.The coronary arteries are known for their wide variations with regard to origin ,course, termination and branching pattern. According to literature coronary anomalies affects about 1% of general population , this percentage is derived from cine-angiograms performed for suspected or suffering from coronary artery diseases, Necropsies yields an even lower incidence, in 18950 necropsies, The incidence of all coronary anomalies is 0.23% in autopsy series (Alexander and Griffith,1956) and ranges between 0.3% and 12% in angiographic series (Chaitman et al., 1976; Engel) variations with a prevalence in the general population of less than 1%, and which are therefore considered as coronary anomalies, are described. In many cases, their presence affects or may affect the subject’s quality of life and even their survival (Angelini et al., 1999;) With the introduction of new surgical procedures an the development of new techniques of cardiac imaging, the normal anatomy, variations and anomalies of coronary arteries have assumed new significance. The coronary arteries may present several variations, in terms of both number and position. The coronary anomalies of the main coronary arteries are described following criteria based on the origin of the anomalous vessel: ectopic aortic origin, origin from the pulmonary artery or origin from a systemic artery. Finally, the congenital coronary continuity and the coronary fistulas are reviewed. Owing to their relatively high rate of prevalence, some of these anomalies may be considered as variations within normal limits, taking the 1% presentation criteria as the limit between variations and anomalies (Levin, 1983; Angelini, 1989), The relationship between the coronary artery branches in the region of the confluence of the atrial, ventricular and atrioventricular grooves, the crux cordis, is called coronary artery dominance and is determined by the artery that emits the posterior interventricular branch. Thus, dominance can be right or left, or balanced circulation can occur when both the coronary arteries emit a branch in that area. According to publications, although the ventricular mass irrigated by the left coronary artery is larger, right dominance is more common . Left dominance seems to be associated with higher mortality due to acute infarction and a higher incidence of arteriosclerosis . Because of the importance of the anatomy in the planning of coronary disease surgeries, the dominance of the circulation is a common theme for discussion in the literature. the number of branches, their location and the myocardial mass irrigated are factors that determine the choice of therapy in all coronary artery bypass grafting (CABG) surgeries, thus surgery is preceded by a detailed analysis using angiographies. Anastomoses between the branches of the coronary arteries, most commonly between the septal branches, branches of the conus arteriosus and atrial branches, are of fundamental importance in acute ischemic syndromes as they may protect part of the involved muscle . Their development is associated to the presence of chronic ischemia
With the aim of contributing to the understanding of
the coronary anatomy and, thus, to heart surgery, this work
is designed with the objective of determining:
• The dominance of the coronary circulation,
• The mean number of branches of the right coronary
artery that supply blood to the left ventricle,
• The mean number of branches of the left coronary
artery that supply blood to the right ventricle,
• The presence of intracoronary anastomoses,
• However, the incidence of coronary anomalies is relevant not only for conceptual and educational purposes but, more importantly, for public health issues, Coronary artery diseases are major cause of death in developing countries so knowledge of anatomical variations ; anomalies of coronary artery is important to clinicians , anatomist , physiologist ,cardiologist, ; thoracic radiologist ,
• The wrong interpretation of a coronary variant or anomaly
might cause technical difficulties during interventional procedures or lead to clinical misdiagnosis or major complications might occur during graft surgery. The need for an accurate anatomical evaluation of the coronary artery tree is relevant during angioplasty, due to revascularization purposes. Coronary anomalies are often asymptomatic and may be accidentally discovered, detection of coronary Anomalies is becoming of major clinical importance. The coronary anomalies cannot be considered just rare aspects because they may often lead to relevant clinical Consequences also.
The objective of this study is to review the anatomy of the coronary arteries using a clinical approach in order to investigate the morphologic presentation of these vessels within the central India population,by different techniques.
3.NORMAL ANATOMY OF CORONARY ARTERIES
3.1.Right coronary artery
3.2.Left coronary artery
3.1 . Right coronary artery
The right coronary artery originates from the right aortic sinus of the ascending aorta. It passes anteriorly and to the right between the right auricle and the pulmonary trunk and then descends vertically in the coronary sulcus, between the right atrium and right ventricle on reaching the inferior margin of the heart, it turns posteriorly and continues in the sulcus onto the diaphragmatic surface and base of the heart. During this course, several branches arise from the main stem of the vessel an early atrial branch passes in the groove between the right auricle and ascending aorta, and gives off the sinu-atrial nodal branch, which passes posteriorly around the superior venacava to supply the sinu-atrial node,
FIGURE NO. 1 – RIGHT CORONARY ARTERY (RED ARROW)
FIGURE NO. 2 – HUMAN HEART ANTERO-LATERAL VIEW SHOWS DIFFERENT BRANCHES OF RIGHT AND LEFT CORONARY ARTERY.
a right marginal branch is given off as the right coronary artery approaches the inferior (acute) margin of the heart and continues along this border toward the apex of the heart as the right coronary artery continues on the base (diaphragmatic surface)of the heart, it supplies a small branch to the atrioventricular node before giving off its final major branch, the posterior interventricular branch, which lies in the posterior interventricular sulcus.
The right coronary artery supplies the right atrium and right ventricle, the sinu-atrial and atrioventricular nodes, the interatrial septum, a portion of the left atrium, the postero-inferior one-third of the interventricular septum, and a portion of the posterior part of the left ventricle.
3.1 Left coronary artery :-
The LCA (Left coronary artery) usually arises from the middle portion of the left anterior sinus of Valsalva, just above the level of the free edge of the open aortic cusp and below the sino-tubular junction, (Williams et al., 1989, Angelini et al., 1999). It lies between the pulmonary trunk and left atrial appendage in the atrioventricular sulcus. The artery is usually embedded in subepicardial fat and does not appear to produce any branches. Termination of the LCA is usually by bifurcation and sometimes, by trifurcation, divided into, the anterior interventricular branch (left anterior descending artery-LAD), which continues around the left side of the pulmonary trunk and descends obliquely toward the apex of the heart in the anterior interventricular sulcus during its course, one or two large diagonal branches may arise and descend diagonally across the anterior surface of the left ventricle, the circumflex branch, which courses toward theleft, in the coronary sulcus and onto the base/diaphragmatic surface of the heart and usually ends before reaching the posterior interventricular sulcus a large branch, the left marginal artery, usually arises from it and continues across the rounded obtuse margin of the heart, a third branch arises in between the LAD and the Circumflex.
FIGURE NO. 3 – A,B,C,D SHOWING DIFFERENT BRANCHES OF RIGHT AND LEFT CORONARY ARTERIES.
This is known as the ramus , intermediate (ramus intermedius) , or optional diagonal coronary artery. The septal perforators (SP) runs into the septum (partition that separates the two ventricles) and provides its blood supply , the distribution pattern of the left coronary artery enables it to supply most of the left atrium and left ventricle, and most of the interventricular septum, including the atrioventricular bundle and its branches .
4.NOMENCLATURE OF CORONARY ARTERIES :-
Nomenclature of the coronary arteries,may be done according to Anatomical texts, (Nomina Anatomica, 1989) employ the use of the following terminology to describe these vessels, Figure The right coronary artery, (RCA) is used to indicate the main stem on the right side ofthe heart. Its main branches are the conus artery, right anterior and posterior ventricular rami, the right marginal artery, nodal arteries to the sinuatrial and atrioventricular nodes and the posterior interventricular artery Surgical texts, (Ochsner and Mills, 1978; Alexander et al., 1998) on the other hand employ the following terminology in their description ofthe arterial pattern: the main stem ofthe right system is called the right coronary artery, Figure . Its main branches are the conus artery, nodal branches to the sinuatrial and atrioventricular nodes, the acute marginal artery, and the posterior descending artery.
Table. 1 showing different nomenclatures of coronary arteries
ANATOMICAL CLINICAL CURRENT STUDY
Right coronaty artery Right coronary artery Right coronary artery
Conus artery Conus artery Conus artery
Right marginal artery Acute marginal artery Right marginal artery
Posterior interventricular artery Posterior descending artery Posterior descending artery
SA and AVnodal arteries SA and AVnodal arteries SA and AVnodal arteries
Left coronary artery Left main artery Left coronary artery
Anterior interventricular artery Left anterior descending artery Left anterior descending artery
Left circumflex artery Left circumflex artery Left circumflex artery
Left marginal artery Obtuse marginal artery Obtuse marginal artery
Diagonal artery Diagonal artery Diagonal artery
Septal perforators Septal perforators Septal perforators
Ramus median/Ramus marginalis Ramus marginalis Ramus intermedius
Table – 1 :- Showing different nomenclatures of coronary arteries
FIGURE NO.4 SHOWING ORIGIN ,COURSE AND BRANCHES OF CORONARY ARTERIES, RCA- RIGHT CORONARY ARTERY, AM –ACUTE MARGINAL, PDA- POSTERIOR DECENDING ARTERY, LAD –LEFT ANTERIOR DECENDING ARTERY, D1-DIAGONAL ARTERY1, D2- DIAGONAL ARTERY2,LCX- LEFT CIRCUMFLEX ARTERY, M1-M2-LEFT(OBTUSE)MARGINAL1-2 ,RV-RIGHT VENTICLE, LV-LEFTVENTRICLE, RA- RIGHT ATRIUM.
FIGURE NO 5 Showing Classification of Coronary Artery Segments. According to American Heart Association (AHA).
The figure also shows the classification between proximal (thick lines) and distal (thin lines) segments
FIGURE No.6. Right-dominant circulation. (A) Diagram of the normal right-dominant coronary artery anatomy. (B) Right-dominant circulation viewed from the diaphragmatic surface of
the heart. Note how the right coronary artery travels in the posterior interventricular sulcus, giving rise to the posterior descending artery.
LM = left main artery; LAD = left anterior descending artery; Cx = circumflex; RCA = right coronary artery; S = septal , D = diagonal,
OM = obtuse marginal; RM = right marginal; RPDA = right posterior descending artery; RPL = right posterolateral; RI = ramus intermediate.
( from: Netter FH. Colacino S (ed). Atlas of Human Anatomy.)
Figure No 7 . Left Anterior View of heat shows vessels attached .
(from .Netter’s Anatomy)
Figure No.8 :- Posterior View of heart shows branches of right and left coronary arteries (from Netter!s Anatomy)
Figure No.9 :- Heart – Postero – inferior view, Diaphragmatic Surface
(from F.Netter’s Anatomy)
4.1. ACC/AHA Coronary Angiography Guidelines and Nomenclature :-
Anatomic angiographic definitions. proper communication of the results of coronary arteriography requires some standardization of nomenclature regarding measurement and description of the coronary arterial tree. Clinical investigators of the CASS, TIMI, and BARI trials have presented standardized systems. These guidelines endorse the system developed by the BARI investigators and published by Alderman and Stadius in Coronary Artery Disease . This system provides for nomenclature of the most frequently encountered coronary arterial segments as shown in Figure and as described in Table . Coronary artery dominance refers to the origin of blood flow to the inferolateral wall of the left ventricle. Right dominance denotes right coronary origin of flow (segments 1 through 9), left dominance to left coronary artery origin of flow (segments 18 and 19 and 23 through 27), and mixed dominance to an intermediate pattern. Coronary artery lesions can be described by their location, severity and classification. Location description uses the scheme shown in Figure , with the proximal shoulder of the lesion defining the location. Stenosis severity may be estimated visually, but is more accurately estimated by Figure .
Figure No.10 :- shows coronary artery segments. Segments 1, 2,3 = right coronary artery; segment 4 = right posterior descending artery; segment 11 = left main artery; segments 12, 13, 14, 15, 16 = left anterior descending artery and diagonal branches; segment 28 = ramus intermedius; segments 18, 19, 19a = circumflex artery; segment 20 = first obtuse marginal branch; segment 21 = second obtuse marginal branch; segment 29 = third diagonal branch. Vessel segments were classified using the BARI (Bypass Angioplasty Revascularization Investigation) classification system
Figure No. 11 The coronary artery map used by the BARI investigators. The map is derived from that used in CASS with the addition of branch segments for the diagonal, marginal and ramus vessels. ( Alderman et al. ). See following Table for corresponding map location.
4.2 Bypass Angioplasty Revascularization Investigation (BARI) Coronary Artery Segments and Corresponding Map Location
Segment Map Location
1 Proximal right coronary artery conduit segment
2 Mid-right coronary artery conduit segment
3 Distal right coronary artery conduit segment
4 Right posterior descending artery segment
5 Right posterior atrioventricular segment
6 First right posterolateral segment
7 Second right postero-lateral segment
8 Third right postero-lateral segment
9 Posterior descending septal perforators segment
10 Acute marginal segment(s)
11 Left main coronary artery segment
12 Proximal LAD artery segment
13 Mid-LAD artery segment
14 Distal LAD artery segment
15 First diagonal branch segment
15a Lateral first diagonal branch segment
16 Second diagonal branch segment
16a Lateral second diagonal branch segment
17 LAD septal perforator segments
18 Proximal circumflex artery segment
19 Mid-circumflex artery segment
19a Distal circumflex artery segment
20 First obtuse marginal branch segment
20a Lateral first obtuse marginal branch segment
21 Second obtuse marginal branch segment
21a Lateral second obtuse marginal branch segment
22 Third obtuse marginal branch segment
22a Lateral third obtuse marginal branch segment
23 Circumflex artery AV groove continuation segment
24 First left postero-lateral branch segment
25 Second left postero-lateral branch segment
26 Third posterolateral descending artery segment
27 Left posterolateral descending artery segment
28 Ramus intermedius segment
28a Lateral ramus intermedius segment
29 Third diagonal branch segment
29a Lateral third diagonal branch segment
Table 2. Bypass Angioplasty Revascularization Investigation (BARI) Coronary Artery Segments and Corresponding Map Location
AV indicates atrioventricular; and LAD, left anterior descending.
4.3 .Nomenclature of the aortic sinuses :-
FIGURE NO..12 :-Shows Nomenclature of the aortic sinuses (“The Leiden Convention”) A schematic representation of the aortic and pulmonary roots as viewed from “above”. The pulmonary root is depicted in blue color while the aortic root is in red. The origins and the approximate initial tract of the coronary arteries is shown with dotted lines. Three coronary trunks , the left anterior descending (LAD) , the circumflex (Cx) and the right coronary (RCA) respectively. The adjacent aortic and pulmonary sinuses (the facing sinuses) are numbered as “sinus 1” and “sinus 2” while the non-adjacent (no facing sinuses) are indicated as “NF”. For a hypothetical observer located within the aortic NF sinus, the right-handed sinus is the aortic sinus 1 (the classical right coronary sinus) and the left-handed, the aortic sinus 2 (the classical left coronary sinus). In an analogous way, the pulmonary facing sinuses a can also be defined.
FIGURE NO.13:-SHOWING SLIT LIKE ORIGIN OF RIGHT CORONARY ARTERY, OVALE ORIGIN OF LEFT CORONARY ARTERY
Following anatomic variants ; Anomalies of coronary arteries are being studied in this study
Prevalence of anatomic variants of coronary arteries
With separate ostium
Two with separate ostia
Sinus node artery
Prevalence of anomalies of coronary arteries
Anomalies of origination and course
High take off
Anomalous origin from opposite sinus
RCA originating from left coronary sinus
LMCA originating from Right coronary sinus
Cx originating from Right coronary sinus
Anomalies of intrinsic coronary arterial anatomy
5. BACKGROUND :-
Knowledge of physiology, normal and variant anatomy and anomalies of coronary circulation is an increasingly vital component in managing congenital and acquired pediatric heart disease. Congenital, inflammatory, metabolic or degenerative disease may involve coronary circulation, and increasingly complex cardiac surgical repairs demand enhanced understanding to improve operative outcomes. “Variability is the law of life,” Sir William Osler.
“The human features and countenance, although composed of some ten parts or a little more, are so fashioned that among so many thousands of men there are no two in existence who cannot be distinguished from one another. Book 7, Sect 8.” Pliny the Elder, AD 23-79.
It is important to understand that no two living organisms are structurally or functionally identical – animals or plants!
It is clear that textbook writers and teachers over the centuries, even until today, fail to understand or to transmit to their students the crucial concept that anatomical and physiological diversity and variation is a canon of living organisms. This failure leads to the belief that textbooks are conveying immutable facts with only few anomalous exceptions.
Variations in coronary anatomy are often recognized in association with structural forms of congenital heart disease. Importantly, coronary artery anomalies are a cause of sudden death in young athletes in the absence of additional heart abnormalities. Understanding the pathophysiology is important in guiding management because variations in coronary anatomy are common. Because of considerable heterogeneity of coronary vasculature, what is considered atypical, abnormal, aberrant, anomalous, accessory, ectopic, incidental, variant, or significant is often unclear. The terms anomalous or abnormal are used to define any variant form observed in less than 1% of the general population.
Coronary arteries (most often 2) are normally the only vessels arising immediately above the free margin of aortic valve from the ascending aorta .The Latin term corona, or crown, aptly describes coronary arteries that supply cardiac parenchyma with nutrient blood flow. The name and nature of a coronary artery or branch is defined by that vessel’s distal vascularization pattern or territory, rather than by its origin.
FIGURE NO.14 :- SHOWING DIFFERENT BRANCHES OF RIGHT AND LEFT CORONARY ARTERIES
The right coronary artery (RCA) most commonly arises separately from an ostium just below the sinotubular junction of the right (right anterior) sinus of Valsalva. The normal anatomy of the coronary arteries is shown in the Figure No.15
FIGURE NO 15 :- Shows Normal anatomy of coronary arteries, viewed from above with the atria removed. A = aortic valve; P = pulmonary valve; T = tricuspid valve; M = mitral valve; RCA = right coronary artery; AM = acute marginal branch of the right coronary artery; CB = conus branch of the right coronary artery; PD = posterior descending branch; AVN = atrioventricular nodal branch; Circ = circumflex coronary artery; OM = obtuse marginal branches of circumflex coronary artery; LAD = left anterior descending coronary artery; Diag = diagonal branches of the left anterior descending coronary artery; Inter = intermedius branch of the left coronary artery.
The RCA courses in the right atrioventricular groove and provides nutrient branches to the right ventricular free wall, extending to the acute margin of the heart. The distal extent of the RCA varies and may extend posteriorly as far as the obtuse margin of the heart. In 90% of patients, the RCA supplies the posterior descending coronary artery branch at the crux of the heart, which supplies the atrioventricular (AV) node and the posterior aspect of the interventricular septum.
The first branch arising from the RCA is the conal or infundibular branch, which courses anteriorly to supply the muscular right ventricular outflow tract or infundibulum. The RCA supplies blood to the atria with a highly variable pattern of small branches. The sinus node artery arises from the proximal RCA in approximately 50% of patients.
FIGURE NO. 16:-Human Heart Antero-lateral superior view Showing origin and course of right and left coronary artery
The left coronary artery (LCA) arises from the mid position of the left (left anterior) sinus of Valsalva (sinuses on either side of the point of aortic and pulmonary commissural contact) just above the level of the free margin of the aortic valve leaflet and generally below the sinotubular junction.
The left coronary ostium is usually single, giving rise to a short, common LCA trunk that branches into the left anterior descending (LAD) and circumflex (Cx) coronary arteries. The LAD courses in the anterior interventricular groove, giving rise to the anterior septal perforating branches as it extends toward the cardiac apex. Small branches may arise from the LAD and supply the anterior wall of the right ventricle. Diagonal branches arise from the LAD and course at downward angles to supply the antero-lateral free wall of the left ventricle.
Figure No. 17 ;- Supero-lateral view of human heart showing short LMCA
( Left Main Coronary Artery)
The circumflex (Cx) coronary artery courses along the left AV groove, around the obtuse margin, and posteriorly toward the crux of the heart. Should the Cx coronary reach the crux of the heart and supply the posterior descending coronary artery, the left coronary system would be termed dominant. This occurs in approximately 10% of patients. Atrial branches may arise from the Cx coronary artery and supply the sinus
FIGURE NO. 18:- Postero- superior view of human heart Showing RCA , LCA and origin of Cx from Aorta
node in 40% of patients. Obtuse marginal branches arise from the Cx system to supply the posterolateral aspect of the left ventricle. In an estimated 70% of patients, a coronary branch (termed ramus medianus, intermedius, or intermediate branch) arises early off the left coronary system to supply an area between diagonal branches from the LAD and obtuse branches from the Cx systems. The heart has a very limited capacity for anaerobic metabolism. The primary source of energy is oxidative metabolism of free fatty acids; therefore, the heart has a negligible ability to tolerate periods of ischemia, yet its capacity to extract oxygen is great (although relatively fixed), and limited degrees of hypoxemia are generally well tolerated. At rest, the oxygen requirement of the heart (8-10 mL/min/100 g) is much greater than of the skeletal muscle (0.115 mL/min/100 g). Exercise requires a 50% increase in oxygen demand primarily met by an increase in myocardial flow 3-4.5 times greater than baseline. The pattern of coronary blood flow is unique. Epicardial coronary vessels serve as capacitance vessels, primarily filling during the period of diastole (as much as 85% of total flow), and intramural pressure and resistance to myocardial perfusion progressively increase from the outer to inner layers of the heart. Myocardial arterioles have tremendous vasodilatory reserve capacity and enable high flow and low resistance in response to exercise. Recent investigations suggest that the coronary vascular tree has a dual mechanism of vasodilatation: larger proximal vessels by endothelium-derived nitric oxide and direct stimulation of smooth muscle cell alpha2-receptors by adenosine and other metabolites.
A coronary artery with an oblique origin, intramural (within the wall of the aorta) course, or positioning between the great arteries puts the coronary arteries at risk for compression and may significantly limit the reservoir capacity of the epicardial coronary system. Comparable pressure in larger vessels creates greater wall tension and is felt to cause compression of smaller vessels.
5.1 HISTORICAL BACKGROUND OF ANATOMY OF CORONARY ARTERIES :-
Interest in the anatomy of the coronary arteries dates as far back as the early 1500’s, at a time when anatomical inquiry was being cautiously aroused. Whilst the later 1700’s encouraged academic domination of anatomical study, significant documentation of the coronary arteries was only been established by the late 1800’s to early 1900’s. There is no doubt that this topic continues to remain dynamic, favored for its value in applied clinical research. Indeed, technological advancement in the 21st century has transformed modem day anatomy into more than just a simple descriptive exercise. Whether to update standard literature, create ethnically specific banks of anatomical data, abate technical difficulties associated with coronary artery surgery or provide exciting interventional possibilities for clinicians, revisiting the anatomy of the coronary arteries is clearly warranted.
6 . A BRIEF REVIEW OF THE WORK ALREADY DONE IN THE FIELD :-
The coronary arteries may present several anomalies, in terms of both number and position. New image-based diagnostic techniques have led to greater reliability in the identification of these anomalies, an in-depth knowledge of the normal anatomy of coronary arteries and their variations being required (Frommelt et al., 2001; McConnell et al., 1995; Post et al., 1995; Ropers et al., 2001). The incidence of all coronary anomalies is 0.23% in autopsy series (Alexander and Griffith, 1956) and ranges between 0.3% and 12% in angiographic series (Chaitman et al., 1976; Engel et al., 1975; Barriales et al., 2001)., Owing to their relatively high rate of prevalence, some of these anomalies may be considered as variations within normal limits, taking the 1% presentation criteria as the limit between variations and anomalies (Levin, 1983; Angelini, 1989), Here, variations with a prevalence in the general population of less than 1%, and which are therefore considered as coronary anomalies, are described. In many cases, their presence affects or may affect the subject’s quality of life and even their survival (Angelini et al., 1999; Basso et al., 2001) , Several major variations in the basic distribution patterns of the coronary arteries occur. Myocardial bridging is a common coronary anomaly characterized by the presence of a muscle bridge above an epicardial artery. Although its involvement in the development of severe cardiovascular pathologies is disputed there are many proofs that it may possibly be associated, in particular circumstances, with sudden cardiac death, the development of malignant arrhythmias, atherosclerosis, myocardial infarction, hibernation or stunning, etc. The development of cardiovascular complications is mainly dependent upon the presence of a significant hemodynamic obstruction. In order for a myocardial bridging to determine such an obstruction The distribution pattern described above for both right and left coronary arteries is the most common and consists of a right dominant coronary artery. This means that the posterior interventricular branch arises from the right coronary artery. The right coronary artery therefore supplies a large portion of the posterior wall of the left ventricle and the circumflex branch of the left coronary artery is relatively small. In contrast, in hearts with a left dominant coronary artery, the posterior interventricular branch arises from an enlarged circumflex branch and supplies most of the posterior wall of the left ventricle . Another point of variation relates to the arterial supply to the sinu-atrial and atrioventricular nodes. In most cases, these two structures are supplied by the right coronary artery. However, vessels from the circumflex branch of the left coronary artery occasionally supply these structure( Post et al., 1995; Ropers et al., 2001), A segment of an epicardial artery that has an intramural course within the myocardium (Geiringer, 1951; Noble et al. 1976).
7. REVIEW OF LITERATURE
7.1 .DEVELOPMENT OF CORONARY ARTERIES
Coronary arteries are the vasa vasorum of the ascending aorta, because the heart is developed from the fusion of two primitive endothelial tubes, which represent the ventral aorta. The right coronary artery arises from the right coronary sinus (anterior aortic sinus) of the ascending aorta and the left coronary artery arises from the left posterior aortic sinus of the ascending aorta ( Datta AK.) As an embryo grows and develops, it soon reaches a size that prohibits simple diffusion of sufficient nutrients and oxygen from the surrounding liquid environment to all tissues. In humans, this occurs by early in the third week. It is fortuitous that the development of the circulatory system is already ongoing at this critical time. The elaborate plumbing system is designed to compensate for increased metabolic demand by conveying the needed materials to the various spaces and masses of tissues that make up the growing individual. The complex but elegant development of the heart is perhaps the most notable feature at this period, first recognized as paired endocardial tubes that soon fuse beneath the forming foregut. During this process, the endocardial tube acquires a layer of presumptivecardiac muscle (known as the myocardial mantle) from the mesoderm adjacent to the forming heart.
The single heart tube then undergoes a sequence of changes apparent from the outside, looping and folding to rearrange the straight tube into the familiar shape of the heart, with the input and output pathways brought closer together and the main pumping ventricle positioned at the opposite apex. During the same period, a well choreographed process of remodeling also progresses on the inside, resulting in the partitions and valves that are the familiar anatomical features of the adult four-chambered heart with a separate pulmonary artery trunk and aorta. The myocardium begins its contractions at approximately the third week (in a human embryo), driving the beginnings of circulation.
The heart continues to pump during the complex morphogenetic changes in its shape and blood flow paths and then throughout the entire lifetime.
The formation of the coronary vasculature involves a series of carefully regulated temporal events that include vasculogenesis, angiogenesis, arteriogenesis and remodeling. (Silva et al., 2009).
Problems of the coronary vascular system lead to major problems with the heart. Although the basic pathways taken by major coronary vessels over the surface of the heart are presented in cardiology textbooks, there is much variation in the pattern which is not well understood. Moreover, the enormity of the coronary system is not well appreciated since all or nearly all cardiac myocytes in mammalian hearts are in contact with capillaries and that the mammalian heart is one of the most vascularized organs of the body. The development and patterning of the coronary vascular system is a relatively unexplored area of vertebrate embryology that has important implications for human health. (Reese et al., 2002).The development of the coronary vascular system is an interesting model in developmental biology with major implications for the clinical setting. Although coronary vessel
development is a form of vasculogenesis followed by angiogenesis, this system uses several unique developmental processes not observed in the formation of other blood vessels (Wada et al., 2003).
Figure NO 19 :- The heart in situ demonstrating the RCA and branches ( Scarpa, 1794)
Formation of the coronary arteries. The coronary arteries were considered for a long time as mere outgrowths of the aortic root (Dbaly et al.; Rychter ; Ostadal; Viragh ; Challice). In 1989, Bogers and colleagues showed that the major coronary arteries could be seen in the aortic wall prior to the emergence of coronary ostia, thus suggesting an ingrowth rather than outgrowth of these vessels (Bogers et al., 1989). Definitive evidence of this pattern was provided in chick-quail chimeras (Poelmann et al., 1993) and in serially sectioned chick (Waldo et al., 1990) and rat (Tomanek et al., 1996) hearts. The roots of the two main coronary arteries are formed when strands from the peritruncal ring of vascular tubes penetrate the aorta at the left and right cusps (Ando et al.). (Vrancken Peeters et al., 1997; Velkey ; Bernanke, 2001).has proposed that , Initially, the proximal ends of the coronary arteries migrate toward the proximal aorta. The tips of the advancing coronary vessels must penetrate the tunica media of the aorta, pierce the endothelial lining, and establish continuity with the lumen. Primarily, several coronary vessels approach the left and right aortic sinuses, but only one of these arteries will establish firm contact with each sinus and become the right and left coronary arteries. The mesenchyme of the approaching epicardial vessels meshes with that of the great vessels, the formation of the coronary arteries in humans follows a similar pattern to that observed in other mammals and birds, arteries in staged embryos of different species. Penetration of the aorta by the tubular network at the aorta’s base is precisely orchestrated so that normally only two major coronary arteries are formed. However, establishment of the coronary ostia is not only spatially, but also temporally, regulated since the left coronary ostium forms prior to the right in both humans and rats (Hirakow; Bogers et al., 1989; Mandarim-de-Lacerda, 1990). There are two models regarding the physiological development of the embryonic coronary arteries. Some authors mentioned that the coronary arteries develop as a budding or outgrowth of the endothelial aortic sinus running towards the adjacent tissue (outgrowth interpretation of the coronary development) (D.baly et al., 1968; Rychter & Ostadal, 1971; Viragh & Challice, 1981). However, the longheld supposition that coronary veins and arteries were formed by outgrowths from the systemic venous sinus and the aorta, respectively, was argued 20 years ago (Bogers et al.1989). In their study, Bogers and coworkers demonstrated that the major coronary arteries could be identified in the walls of the aortic sinuses before the emergence of coronary arterial orifices, thus suggesting ingrowth rather than outgrowth of the arterial channels. The roots of the right and left coronary arteries are formed when strands from a peritruncal ring of vascular structures penetrate the aorta at the right and left aortic sinuses of Valsalva (Ando et al., 2004).Thus, at the end of the vasculogenic period without blood flow, the general pattern of the coronary system is set.The reasons for confinement of the coronary ostia on two of the three aortic sinuses are still unclear. Microscopic examination of serial sections of human embryos from 5.0 to 17.5 mm CR length (Carnegie stages 13-19) confirmed that the earliest vessels in the heart wall develop subepicardially near the apex at stage . The network extends centripetally and only at stage could coronary arterial stems, communicating with the aortic lumen, be identified. The sequence suggests that confinement of the coronary ostia to the interior of both the right and left posterior sinuses probably occurs because these represent the most accessible contact points for the centripetally growing vascular plexus (Turner & Navaratnam, 1996)
Vasculogenesis :- The initial steps in the formation of the vascular system during embryonic life involve the differentiation of mesodermal cells into angioblasts that give rise to endothelial cells forming the first primitive blood vessels.
7.2 .Coronary arterial anomalies and variations :-
Coronary anomalies may occur in nearly 1% of the general population and refers to a wide range of congenital abnormalities involving the origin, course, and structure of epicardial coronary arteries. (Davidavi cius et al., 2004). Congenital abnormalities of the coronary arteries are an uncommon, but important cause of chest pain and sudden cardiac death. (Kim et al., 2006). Although the spectrum of symptoms and associated syndromes is broad, the coronary artery anomalies that give rise to symptoms are limited to those that cause significant alteration in myocardial perfusion or result in pronounced left-to-right shunting (steal). The coronary anomalies most likely to cause myocardial infarction, ischaemia, or ventricular tachycardia are anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA), large coronary arteriovenous fistulas, and those anomalies associated with a coronary artery coursing between the great vessels. The other coronary artery anomalies are rarely associated with symptoms or sudden death. (Hauser, 2005). In the transeptal vessel, the anomalous vessel crosses the crista supraventricularis and the interventricular septum (Kimbiris et al., 1978; Virmani et al., 1989). This situation presents characteristics that are partially similar to those
observed when the left coronary artery originates in the right aortic sinus, or in cases of a single orifice located in the right aortic sinus, both with a transeptal path of the main left trunk. The transeptal path of the anterior interventricular artery of ectopic origin is a rarely observed anomaly, and only a few cases have been described (Bochdalek, 1867; Sanes, 1937; White and Edwards, 1948; Saner et al., 1984; Schulte et al., 1985; Reig et al., 1989; Congenital malformations of the coronary arteries in otherwise normal hearts were previously categorized as major or minor. Major anomalies are those that produce symptoms and minor anomalies are those that are of no clinical relevance. The currently preferred method of categorization has an anatomical basis; and such a descriptive categorization system allows anomalies to be grouped in the following way: a) a group involving anomalous origin of the coronary arteries from arterial roots, b) anomalies with abnormal epicardial course c) anomalous connections between other coronary arteries; and finally a combination of all. (Bolcal et al., 2006). Coronary anomalies may be unique findings or associated with major congenital heart diseases, such as valvular lesions, including the bicuspid aortic valve and the tetralogy of Fallot, transposition of the great arteries. (Schmitt et al., 2005). Evaluation of coronary artery anomalies is performed by using catheter-based angiography. However, the precise course of the vessel may not be adequately defined with this technique. Magnetic resonance (MR) imaging has often been used to delineate the anomalous coronary artery in equivocal cases; however, MR imaging can be limited by low spatial resolution and artifacts and can be technically challenging. Recently, the development of multi–detector row computed tomography (CT) has permitted better definition of the coronary vessels with CT. (Datta et al., 2005). Despite the position of the heart within the chest and the position of the great arteries as they arise from the heart, aortic and pulmonary valves normally have a single point of contact, with commissural apposition at this point. Coronary arteries almost always arise normally from the “facing” sinuses of Valsalva on either side of this point of commissural contact. Coronary arteries do not normally arise from “nonfacing” or most distant sinus; however, variations in coronary anatomy are common. Variations that occur in less than 1% of the general population may be considered abnormal or anomalies. In addition to coronary angiography, trans-oesophageal echocardiography also may clinically detect coronary anomalies, but this method is not totally noninvasive and is too costly for screening large populations. (Angelini et al., 2002).
7.3.Variations in the distribution patterns of coronary arteries :-
Several major variations in the basic distribution patterns of the coronary arteries occur (Horia Muresian et.al.) The distribution pattern described above for both right and left coronary arteries is the most common and consists of a right dominant coronary artery. This means that the posterior interventricular branch arises from the right coronary artery. The right coronary artery therefore supplies a large portion of the posterior wall of the left ventricle and the circumflex branch of the left coronary artery is relatively small. In contrast, in hearts with a left dominant coronary artery, the posterior interventricular branch arises from an enlarged circumflex branch and supplies most of the posterior wall of the left ventricle . Another point of variation relates to the arterial supply to the sinu-atrial and atrioventricular nodes. In most cases, these two structures are supplied by the right coronary artery. However, vessels from the circumflex branch of the left coronary artery occasionally supply these structures. A clear-cut and clinically-useful definition of a coronary anomaly is frequently not easy to obtain; many variables are to be taken into account. Because no unanimous agreement exist on the terms and classifications to be used, comparisons between various centers and between different series, are thus difficult to perform. The finding of an coronary arterial anomaly eventually raises lots of further questions due to the fact that it is difficult to make a parallel between an anatomical modification and its alleged clinical consequences, especially regarding the most severe ones such as dysrhythmias, myocardial ischemia and sudden death. The present review is intended to represent an aid to the clinician and aims to bridge the inherent gaps between the points of view of the specialists who directly approach this topic, angiographist, cardiologist, cardiac surgeon, pathologist and Anatomist. Thus, useful definitions, classifications, data of clinical relevance and treatment guidelines, are given – especially under the light of the new theories and updated concepts. The coronary system consisting of two coronary arteries appears to be a relatively recent evolutionary acquisition fish and amphibian have only one coronary artery and only 60% of avian species have two coronaries. The human coronary arteries show a predominantly subepicardial course and frequent intramural course (the so-called myocardial bridging- Figure No. 20 Antero lateral view of Human Heart ) a disposition between that found in some species with a completely intramyocardial course (rat, guinea pig, hamster) and respectively, of other species, with entirely subepicaridal arteries (horse, cow, pig). The right and left coronary arteries normally originate from the homonymous aortic sinuses adjacent to the pulmonary trunk (the facing sinuses). For a clearer definition and classification of coronary arterial disposition especially in complex congenital cardiopathies, a useful system was developed . This scheme allows a universal and precise characterization of any type of coronary variation or anomaly, no matter the relative position of the aorta and pulmonary trunk to each other or related to the remainder cardiac structures The right coronary artery usually courses as a single trunk; the left main coronary artery generates the left anterior descending and the circumflex branches: thus, three coronary arterial trunks eventually result. Taking into account the variability of coronary arterial origin and proximal course, the variable length of the left main trunk as well as the various diagnostic and therapeutic implications, attention has been focused on the three essential, elementary coronary trunks: left anterior descending (LAD), circumflex (Cx), and right coronary artery (RCA).
The coronary circulation can be divided into extramural and intramural portions. The extramural component comprises the three essential trunks and their primary divisions. They run in the subepicardial layer showing a tortuous course (a feature already present in the newborn), due to the fixation to the myocardium by means of the penetrating intramural branches and to the direction of the vessels which predominantly coincides with that of the heart movements. A major characteristic of the extramural vessels unique to the coronary arteries is their sub-intimal fibro-muscular-elastic thickening, already developing during the first months of life. The intramural vessels penetrate deep into the myocardium.
FIGURE NO. 20 :- Antero-lateral view
Of Heart is showing Myocardial
bridges (MB), LAD-(Left anterior
descending artery), D1-Diagonal branch
of LAD, LMCA- (Left main coronary
artery ),LV –Left Ventricle
They originate approximately at right angle and follow a more or less perpendicular course to the plane of the ventricles. The intramural branches course through the whole thickness of the ventricular wall giving off successive ramifications which will eventually form a fine vascular network present at all levels (rather than only at subendocardial or subepicardial levels, as previously thought).
Anastomosis : – Abundant anastomoses are present between
the branches of the same coronary trunk (intra or homo-coronary anastomoses) or between branches of different coronary trunks (inter- or hetero-coronary anastomoses). Intracoronary anastomoses are shorter (1-2 cm) , as compared with the intercoronary anastomoses
7.4 . CORONARY ARTERY MINIMALLY REQUIRED FEATURES :-
Minimal Criteria for Normal Coronary Arteries
(1) The aorta arises dually from the right and left coronary cusps (the ones adjacent to the aortopulmonary septum).
(2) The right coronary artery follows the atrioventricular groove.
(3) The left coronary artery lies behind the pulmonary artery and has a main trunk of variable length that divides into two branches: the left anterior descending (LAD) and the circumflex (Cx) coronary arteries. The LAD follows the interventricular groove and forms septal perforator branches, and the Cx follows the left atrioventricular groove.
(4) The posterior descending branch originates from either the right or left coronary artery, follows the posterior interventricular groove, and divides into septal perforator branches.
(5) The major coronary branches flow epicardially (extramurally).
(6) The coronary arteries terminate at the capillary (myocardial) level.
CORONARY ARTERY MINIMALLY REQUIRED FEATURES
Left anterior descending (LAD) Location: the anterior interventricular sulcus
Subepicardial position (but not infrequently intramyocardial)
Provides septal branches and follows the direction of the septum.
Accompanied by a conspicuous venous branch (greater cardiac vein)(1)
Circumflex (Cx) Location: the left side of the coronary sulcus
Provides at least one marginal branch(2)
Right coronary artery (RCA) Location: the right side of the coronary sulcus
Provides at least the right (“acute”) marginal branch(3)
TABLE . 2. The elementary coronary arteries (Adapted from Angelini et al., 2002 )
(1)These represent the essential features of the LAD, no matter what origin it might have (e.g. not always from the aortic sinus 2, as it occurs in TGA). Its proximal course can also be very different (pre-infundibular, between the aorta and pulmonary trunk or intraseptal).
The LAD can be split or doubled; it may give off few diagonal branches. It may also show an important and longer recurrent tract at level of the posterior interventricular sulcus. Even in complex cardiac
Figure No. 21:- A) Antero-lateral view of heart showing injection of contrast media
B) showing C)postero-lateral view of heart showing red arrow –RPDA (Right posterior descending artery, Green arrow –Acute marginal branch of RCA(Right Coronary Artery), after injection of Contrast media (Red colored)
D) Human heart showing red coloured contrast media after injection
malformations, such as in criss-cross hearts with a horizontal interventricular septum , the LAD always follows the septum.
(2) In some instances, the Cx might show a more “atrial” or respectively, a more “ventricular” course (i.e. nolying exactly at the level of the coronary sulcus) – a disposition of surgical relevance
Figure No.22 A) Antero-superior view of heart showing LMCA (Left main coronary artery), RCA (Right coronary artery), Conus artery originating from Aorta
B) superior view of heart showing red arrow –origin of coronary artery , Green arrow –Aortic sinuses
C)Postero-lateral view of heart showing red arrow –RPDA (Right posterior
descending artery, Green arrow –Acute marginal branch of
RCA(Right Coronary Artery), after injection of Contrast media (Red colored)
D) Human heart showing red coloured contrast media after injection
Figure No.23:-.Antero-lateral view of the Heart LCA system
The heart is orientated to bring the anterior & lateral view into focus. The first branch of the LMCA passes superiorly to supply the left atrium. atrial branch and by the epicardial tissue of the left atrial appendage. In this specimen, LAD artery hugging the lower limit of the left atrium .
(3)Variations in caliber and length of the RCA should be interpreted taking into account the conus artery (which might have a separate origin or which at times can be of considerable dimension: “the third coronary artery”).
The conus artery may also originate at level of the aortic sinus 1 (e.g. TGA) The RCA might practically end (or become insignificant) after giving off the right (acute) marginal branch. The origin and course of the sinus node artery are very important for the surgeon.
7.4 THE DEFINITION OF A CORONARY ANOMALY
Like many other tissues and organs in the body, the coronary arterial system can show variable features that can be regarded either as
“normal” or “abnormal”. A clear distinction is often difficult to make as many of the coronary arterial variations are at the innocuous end of
the broad clinical spectrum of possible consequences; in other cases, a direct causal relationship between a coronary anomaly and an unusual event as sudden death, is difficult to prove. Even more, variations regarding for example the number of ostia, location, size, the proximal course, may actually mean nothing and this aspect can be certified by using the various diagnostic methods that prove the adequacy of myocardial perfusion. An important detail is represented by the regional distribution of a coronary artery, its actual denomination and origin being of less importance. The surgeon or the hemodynamist must have clear in mind which branch vascularizes a given territory and how many of such vessels must be approached; their actual origin or denomination is of secondary importance. For example, a diagonal branch can represent in some cases the main source of blood to the anterior left ventricular wall and to the mitral anterior papillary muscle group, while in others; it may just be a slender and less important branch. Probably, unless a major anomaly exists (vide infra), the subepicardial course of a coronary artery is of no particular significance or it may represent an alteration of the normal process of coronary genesis, in which case however, a clear-cut demarcation between “normal” and “abnormal” is not as obvious as it might be expected.
The variable features of the coronary Arteries :-
1.Ostium Number of Ostia
Angle of origination
Shape (e.g. slit-like; membrane like
Presence of a diaphragm
3. Proximal course Particularly intramural tract
Consider angle of origin
4. Mid-course Intraseptal tract or looping
5. Intramyocardial ramifications Regional distribution
6. Termination Regional distribution
TABLE . 3. The variable features of the coronary arteries( Angelini P et. all )
In defining an anomaly or variation, some important features of the Coronary Arteries should be taken into account (Table 3). Following the criteria presented in the table, “abnormality” can be looked upon as a quantitative variation (e.g. number of ostia) or by demonstrating very particular features: very small ostium or trunk, acute angle of origin,
Figure No. 24 :-Postero-lateral view human heart showing RCA (Right Coronary Artery ) and acute marginal branch arising from RCA
Obstructive membrane, lack of the proximal part of one coronary. With some other features, empirical criteria could be applied: “what is observed in less than 1% of the population or what is more that 2 standard deviations of a Gaussian distribution curve” . Strict definitions should thus be issued by certified groups of experts on larger statistics – a task still difficult to accomplish It is also difficult and quite unnatural to call as “anomaly”, a variation observed only at the level of the larger conduits (subepicardial vessels and their main branches) while ignoring their effect or associated lesions at microcirculatory level. Cases with coronary stenoses or occlusions and normal myocardial scintigram or in otherwise normal people are encountered; on the other hand, cases with normal coronary arteries and altered myocardial perfusion are also present. There is no relationship between the number of stenosis, degree of stenosis and the severity of ischemic heart disease and no correlation with the location, size and severity of an infarct . The picture is thus complex and incompletely resolved yet. Even when taking into account the three elementary coronary trunks, a pertinent comparison between different studies can not be made and the often-used classification of coronary lesions in “one-, two- or three-vessel disease” has little significance if no mention is made regarding the distal territory of each trunk, the coronary typology and the relative balance between the trunks. The clinical consequences do represent another valid criteria for defining a coronary anomaly. There are anomalies involving obligatory ischemia , such as the origin of the left coronary artery from the pulmonary trunk . At the other end of the spectrum there are anomalies not associated with ischemia. In between these categories, there is an ill-defined group of anomalies involving exceptional ischemia, that allow a normal life and even athletic activity ,evolving with time in the same patient. Is there any gradual development of symptoms during the natural history of a given anomaly and can a threshold be established? What would be, for example the significance of an atherosclerotic lesion developing on an anomalous coronary branch.
Following the various statistical evaluations and extrapolations, it results that millions of people should be the bearers of a coronary anomaly (0.2-1.2% of the general population) (Levin, 1983; Angelini, 1989) but most of these, are either asymptomatic or undiagnosed ,Is there a causal relation between a rare event as sudden death and an otherwise uncommon condition such as a coronary anomaly, and can this be demonstrated (Longenecker et al., 1961) and if, in how many of the patients. Are preventive measures and therapies justified. In what measure these anatomical variations can influence on the pathological process; and do they have a predominant or auxiliary role in the disease process? In order to produce unfavorable clinical conditions, are additional factors such as spasm, compression, hypertrophy, dysrhythmias or clotting disorders, required? Are these anomalies and their effect. The physician should concentrate on the possible relationship between anomaly and symptomatology, alteration of the diagnostic Probably, in this respect, the classification of coronary anomalies in “major” and “minor” makes more sense, though, some of the so called “minor anomalies” are not “minor” at all, as for example the abnormal origin of the left coronary from the right aortic sinus (1LCxR) which is associated with sudden death or myocardial infarction. Some of the coronary arterial anomalies are acquired (aneurysms, fistulas, some forms of single coronary artery) and consequently, the term „congenital” should be applied only in selected cases. (Levin, 1983; Angelini, 1989)
7.5 CLASSIFICATION OF CORONARY ARTERIAL ANOMALIES
Due to the different definition criteria, a universally accepted classification is difficult to be elaborated. A synthetic classification is
given in Table 3.
TABLE 4. Synthetic classification of the coronary anomalies
Following are the coronary anomalies of clinical surgical relevance
1. Anomalous pulmonary origins of coronary arteries (APOC).
2. Anomalous aortic origins of coronary arteries(AAOC).
3. Congenital atresia of the left main coronary artery (CALM)
1 Anomalous pulmonary origins of coronary arteries (APOC).
Anomalous aortic origins of coronary arteries(AAOC).
3 Congenital atresia of the left main coronary artery (CALM)
In Coronary Artery Anomalies, Angelini comprehensively classifies coronary anomalies in (normal) human hearts as follows:
Anomalies of origination and course
1. Absent left main trunk (split origination of LCA)
2. Anomalous location of coronary ostium within aortic root or near proper aortic sinus of Valsalva (for each artery):
3. Anomalous location of coronary ostium outside normal “coronary” aortic sinuses
1. Right posterior aortic sinus
2. Ascending aorta
3. Left ventricle
4. Right ventricle
5. Pulmonary artery Variants:
1. LCA arising from posterior facing sinus
2. Cx arising from posterior facing sinus
3. LAD arising from posterior facing sinus
4. RCA arising from anterior right facing sinus
5. Ectopic location (outside facing sinuses) of any coronary artery from pulmonary artery
? From anterior left sinus
? From pulmonary trunk
? From pulmonary branch
6. Aortic arch
7. Innominate artery
8. Right carotid artery
9. Internal mammary artery
10. Bronchial artery
11. Subclavian artery
12. Descending thoracic aorta
4. Anomalous origination of the coronary ostium from opposite, facing “coronary” sinus (which may involve joint origination or adjacent double ostia). Variants:
1. RCA arising from left anterior sinus, with anomalous course:
1. Posterior atrioventricular groove* or retrocardiac
3. Between aorta and pulmonary artery†
5. Anterior to pulmonary outflow† or precardiac
6. Posteroanterior interventricular groove†
2. LAD arising from right anterior sinus, with anomalous course:
1. Between aorta and pulmonary artery
3. Anterior to pulmonary outflow or precardiac
4. Posteroanterior interventricular groove
3. Cx arising from right anterior sinus, with anomalous course:
1. Posterior atrioventricular groove
4. LCA arising from right anterior sinus, with anomalous course:
1. Posterior atrioventricular groove† or retrocardiac
3. Between aorta and pulmonary artery†
5. Anterior to pulmonary outflow† or precardiac
6. Posteroanterior interventricular groove†
5. Single coronary artery
Anomalies of intrinsic coronary arterial anatomy
6. Congenital ostial stenosis or atresia (LCA, LAD, RCA, Cx)
1. Coronary ostial dimple
2. Coronary ectasia or aneurysm
7. Absent coronary artery
8. Coronary hypoplasia
9. Intramural coronary artery (muscular bridge)
10. Subendocardial coronary course
11. Coronary crossing
12. Anomalous origination of posterior descending artery from anterior descending branch or septal penetrating branch
13. Absent PD (split RCA)
1. (Proximal + distal) PDs, both arising from RCA
15. Absent LAD (split LAD). Variants:
1. LAD + first large septal branch
2. LAD, double
16. Ectopic origination of first septal branch
Anomalies of coronary termination
17. Inadequate arteriolar/capillary ramifications
18. Fistulas from RCA, LCA, or infundibular artery to:
1. Right ventricle
2. Right atrium
3. Coronary sinus
4. Superior vena cava
5. Pulmonary artery
6. Pulmonary vein
7. Left atrium
8. Left ventricle
9. Multiple, right + left ventricles
2. Anomalous collateral vessels
*If a single, common ostium is present, the pattern is considered to represent “single” coronary artery
7.6 CORONARY ANOMALIES (VARIATIONS) AND PATHOPHYSIOLOGICAL CONSEQUENCES :-
All of these depend on the type of coronary anomaly and on “the demonstrability” of such. In case of abnormal origin from the pulmonary
trunk, or of coronary fistulas, the pathophysiology is more evident and the therapeutic measures follow an algorithmic approach. In other cases, there may not be such a direct causal relationship and indications and timing may differ.
7.7. 1. Abnormal origin from the pulmonary artery (APOC)
Abnormal origin from the pulmonary trunk or artery may cause: myocardial ischemia (or infarction), mitral insufficiency, congestive heart failure and death in early infancy. The main pathophysiological mechanism is represented by the impoverishement of left ventricular myocardial blood flow due to retrograde flow toward the pulmonary trunk through the intercoronary anastomoses (the surgical creation of a two-artery coronary system is thus mandatory). The ALCAPA may serve as a paradigm: during the neonatal period high pulmonary vascular resistance and resultant pulmonary artery pressure ensure antegrade flow from the PA to the anomalous coronary artery; as this pressure decreases the flow eventually reverses with resultant left-to-right shunting (into the pulmonary trunk). In face of this coronary steal the myocardial perfusion becomes dependent on the RCA by means of intercoronary anastomoses. The rapidity of this sequence divides patients in two categories: the infantile type and respectively the adult type . The infantile type has few or no collaterals and myocardial ischemia ensues rapidly with all the signs of myocardial ischemic dysfunction present. Infants present with poor feeding probably due to angina, tachypnea, tachycardia and over heart failure. Such clinical findings are however difficult to distinguish from those of cardiomyopathy or endocardial fibroelastosis. Electrocardiographic signs of anterolateral infarction can be present, along with those of left ventricular hypertrophy. Myocardial enzymes can be elevated. Cardiomegaly and interstitial pulmonary edema are present on the chest X-ray. Prompt surgical decision is needed; otherwise premature deterioration and death supervene The adult type accounts for 10-15% of the patients survival is aided by the presence of large collaterals. Clinical presentation with fatigue, dyspnea, palpitations and effort angina can develop beyond age 20 but in some cases, the patients can still remain asymptomatic with a nonspecific cardiac murmur (apical pansystolic) as a consequence of mitral regurgitation (this latter sign can sometimes dominate the clinical picture). The ECG is abnormal, revealing signs of an old anterolateral infarction. Cardiomegaly may be present.
7.7.2 . Abnormal aortic origin (AAOC) :-
Abnormal aortic origin is usually benign except the origin of LMCA from sinus 1 and of the RCA from sinus 2, which can be associated with cardiac symptoms and sudden death. The origin of LMCA from sinus 1 with course between the great arteries is associated with the greatest risk of sudden death, even up to 82%9. The intramural course or between the great arteries is alleged to produce compression of the abnormal coronary, though not always demonstrated. Under these circumstances, intravascular ultrasound or myocardial perfusion scan might represent valuable diagnostic tools. Stretching of the abnormal left coronary might represent the main pathophysiologic mechanism in systole; during diastole the artery can be compressed by the closely related intercoronary commissure Other associated lesions and mechanisms, besides compression or stretching of the anomalous coronary artery may supervene in cases with AAOC: single ostium located near a valvar commissure, slit-like aortic orifice, a very oblique origin and proximal tract. Clinical or ECG features are not characteristic. Angiography can be diagnostic in patients with exertional angina or syncope. ( Engel et al., 1975; Barriales et al., 2001) When stretching of the coronary artery is the main mechanism, concomitant injection in the anomalous coronary and the PT is of diagnostic value23. Surgical solution is represented by coronary artery bypass grafting, reconstruction and reimplantation of the origin of the anomalous coronary trunk, unroofing of the intramural tract or division and reimplantation.
7.7.3. The single coronary artery :-
Definition: only one ostium is present and the coronary artery originating from the single ostium vascularizes the entire heart. It can present with no intrinsic abnormalities of the artery or with associated intrinsic modifications such as: aneurysm or anomalous communication with a cardiac chamber. The single coronary artery can present under various forms Type I: “true single coronary”: one artery supplies the entire heart , Type II: single artery divides in RCA and LCA (actually 2 coronaries with common aortic origin),
Type III: other atypical patterns. This anomaly is considered “minor”. Its pathological significance is related to lesions or disease processes affecting its proximal course that might induce dramatic events. In addition, single coronary artery may be the single “anomaly” or it may be part of the larger picture of complex malformations of the heart (tetralogy of Fallot, DORV, persistent truncus arteriosus, pulmonary atresia with intact septum, TGA, etc.) Single coronary orifice This anomaly, sometimes also known as single
coronary artery, is characterised by the absence of the proximal portion of one of the coronary arteries, with the distal portion usually in its normal location (Ogden and Goodyer, 1970). Its existence was first noted by Columbus (1559), although Thebesius (1716) published the first description. The incidence of single coronary orifice not associated with congenital cardiopathies is low, and has been placed at 0.04% for the general population (Alexander and Griffith 1956) and 0.2% – 0.4% in angiographic series (Hillestad and Eie, 1971; Baltaxe and Wixson, 1977; Neufeld and Schneeweiss, 1983). A single coronary artery originating in the right aortic
sinus is slightly more frequent than in the left (51% vs. 49%) (Ogden, 1968). The single right coronary artery also presents a higher number of pattern variations. An association between the presence of a single coronary orifice and anomalies in the aortic valve has been described, especially with the bicuspid (Hillestad and Eie, 1971) and tetracuspid (Kim et al., 1988) aortic
valves. From the single coronary orifice, four paths – preventricular, interarterial, transeptal and retroaortic – may be followed by the anomalous
artery (McAlpine, 1975). The least commonly described arterial path is the transeptal one , in which the anterior intraventricular artery, a branch of the single coronary artery originated in the right aortic sinus, crosses the crista
supraventricularis and the interventricular septum. Descriptions of this variant have been published in a few cases (Bochdalek, 1867; Sanes, 1937; White and Edwards, 1948; Saner et al., 1984; Schulte et al., 1985; Reig et al., 1989; Dollar and Roberts, 1989). On this path, an increase in the elastification of the intimal layer of the transeptal vessel can be seen, together with a marked fibrosis of the middle layer, which gives it the appearance of a venous vessel (Reig et al., 1989). The interarterial path of the single coronary artery has been associated with sudden death (Sharbaugh and White, 1974). In the other possible paths, its course is benign, although in the case of arteriosclerotic occlusion of the single artery, its consequences are often fatal (Cheitlin et al., 1974, Roberts et al 1982). the retroaortic path being less common .The inter-arterial path has been associated with sudden death, especially during or immediately after intense exercise (Cheitlin et al., 1974; Barth and Roberts, 1986). This is due to the compression of the ectopic orifice, or compression of the left coronary artery owing to the expansion of the aortic and pulmonary roots during intense exercise.
The anterior path of the large vessels does not present relevant haemodynamic problems. However, when this anomaly is associated with
a tronco-conal congenital cardiopathy, such as Fallot’s tetraology, there is the possibility of accidental injury to the left coronary artery or the anterior interventricular branch during surgical handling of the pulmonary infundibulum. The interarterial path of the ectopic left coronary artery rises slightly after its origin, followed by an anterior incurvation around the aortic root, between the latter and the pulmonary root. It then assumes a posterior concavity until it reaches the left coronary artery’s normal position,
where it divides into its final branches. Between the two great arteries, the left coronary artery is usually located below the level of the pulmonary
valve (Liberthson et al., 1974).
7.7.4. Congenital atresia of the left main coronary artery (CALM) :-
This pattern is different from the single coronary in that a single RCA feeds the entire heart but flow in the LAD and Cx is not centrifugal but centripetal (i.e. retrograde). There is no ostium of the left main coronary artery and the proximal LMCA ends blindly. All known anastomoses between the left and right system may be apparent. The Cx and LAD are in normal position. This anomaly offers an example in favor of the theory of ingrowth of the proximal coronary trunks toward the aorta. There are few cases described in the literature. Clinical consequences depend on the superimposed lesions (e.g. atherosclerotic). An association was found with supravalvular aortic stenosis especially in William’s syndrome. (Chaitman et al., 1976 ) The literature contains reports of coronary arteries that have become stenosed because of a membrane or fibrotic ridge located at or near the aortic orifice ofan otherwise normal heart. This condition may be associated with tangential origin ofthe coronary artery. In extreme cases, LAD and RCA may be affected. This anomaly characteristically presents with one or more of the following anatomical features:
(a) Proximal occluded artery has a larger diameter than the intermediate segments,
(b) One or more collateral connections are present,
(c) Proximal anatomy ofthe occluded vessel has a blind pouch that adjoins an aortic sinus,
(d) The site of ostial atresia is sometimes recognizable as a dimple in the related aortic sinus,
(Angelini et al., 1999).
7.7.5. Coronary arteriovenous fistulas (CAVF) :-
A coronary fistula is a direct communication between a coronary artery and the lumen of any of the cardiac chambers, the coronary sinus (or one of its tributary veins), the superior vena cava, the pulmonary artery or veins close to the heart (left heart fistulae are in fact arterioarterial, arterio-cameral or arterio-systemic). The picture is protean, depending on the number of fistulas, their origin, their drainage, association with other cardiac pathologies, etiology (congenital or acquired), localization at the level of the coronary artery (i.e. proximal or distal), the status of the myocardium. More than 90% of the fistulae open into the right heart Positioning within sinuses-Coronary arteries arise more or less perpendicular to the aortic wall. The incidence of coronary fistulas in angiographic series varies between 0.1% and 0.2% (Said et al., 1997; Barriales et al., 2001). They account for 0.40% of congenital cardiopathies (Neufeld and Schneeweiss, 1983). Fistulous
communications may originate both in the right and left coronary arteries, although a slightly higher incidence has been described in the left artery. The vessel of origin is dilated and twisted in appearance, owing to the increase
in blood flow. The termination point of arterial fistulas is located mostly in the right cavities or in the pulmonary artery (Arani et al., 1978; Levin, 1983;, just above the free leaflet margin of the aortic leaflet and below the sinotubular junction. Coronary arteries that arise ectopically usually course tangentially to the aortic Bosc et al., 1985; Said et al., 1997).Ostia are located in the middle of the sinus wall or arise in close relationship to the commissure of the aortic valve. chambers or their connecting vessels, arterial pressure pulse is seldom greatly widened. Presentation is late in life (occasionally in childhood). Most patients with a continuous murmur, mild cardiomegaly or pulmonary plethora. The most common symptoms are effort dyspnea and fatigue; angina in uncommon, myocardial infarction is rare; some patients are asyptomatic. The apearance of heart failure is related to the duration of fistula(s) and not to the amount of shunting. The ECG may be normal or show signs or ventricular (right or left) overload. If the fistula is large enough, the diagnosis can be made two-dimensional and Doppler echography. A special distinction must be made in case of pulmonary atresia with intact ventricular septum, with right ventricular-dependent circulation. In cases without a connection between a proximal coronary artery and the aorta (or with severe luminal stenosis / occlusion), part or all of the coronary circulation is dependent upon perfusion from the RV. Any maneuver that might obliterate the RV cavity (e.g. thromboexclusion, tricuspid oversewing) or that decompresses the RV (e.g. RVOT reconstruction), will exacerbate ischemia. In cases with continuity between the aorta, coronary arteries and RV, a bidirectional flow in the coronaries might exist. Many patients exhibit ischemia due to a diastolic steal phenomenon. Lowering the RV pressure (as with the use of prostaglandins or the creation of a systemic-to-pulmonary shunt) may worsen the steal phenomenon and exacerbate ischemia. A distinction must be made between myocardial sinusoids and the ventriculo-coronary arterial connections. The myocardial sinusoids connect first to a capillary bed which is itself continuous with the epicardial coronary arteries. The ventriculo-coronary connections represent direct communications. Fistulas can be closed from within the cardiac chamber involved, or through the enlarged coronary itself. Ligature or coronary bypass are other techniques indicated. Aneurysmal dilatations of the coronary arteries should be also addressed. (Reig,et.all 2003).
7.7.6. Complete transposition of the great arteries (TGA) :-
Many anatomical variations and anomalies of the coronary arteries are described in the various forms of TGA and these will not be reviewed here. The relative position of the aorta and pulmonary trunk and the coronary disposition, pose important problems in view of the surgical correction. The “normal” coronary disposition in TGA is: 1LCx 2R (the disposition appears inverted as compared with the disposition in the normal heart). The most frequent anomalies encountered are: 1L 2RCx, 1Cx 2RL, 1R 2LCx, 2LCxR, 2RLCx, 2 CxRL 1RLCx.. These may pose special surgical problems or even contraindicate the switch at arterial level. (Engel et al., 1975; Barriales et al., 2001)
Figure no 25 :-The 9 most common variations of coronary artery anatomy in d-TGA.
ANT = anterior; Cx = circumflex; d-TGA = complete transposition
of the great arteries; LAD = left anterior descending; LCA = left
coronary artery; R = right; RCA = right coronary artery
(From: Wernovsky G, Sanders SP. Coronary artery anatomy and
transposition of the great arteries. Coron Artery Dis 1993;4:
148-57.12 From Lippincott Williams ; Wilkins, Baltimore.)
7.7.7. Myocardial bridges :-
The incidence at catheterization is 0.5-16% in at least 60% of hearts and range from 5.4 to 85.7%. Generally, a myocardial bridge is while in the general population, it is estimated at 5.4-85.7%9. Myocardial bridges are present recorded to be about 2.3-42.8 mm in length, (Kosinzki and Grzybiak, 2001), Angelini,1983), The most frequent location of MB is on the left anterior descending artery (anterior interventricular artery – AIVA). Anatomic studies depicted a medium incidence of AIVA MB ranging around 58% (data obtained by computing the results from (Bestetti RB, Costa RS, Kazava DK, Oliveira JSM-1991)whilst angiographic studies revealed an incidence of over 98% (data obtained by computing the results
obtained from Somanath H, Reddy K, Gupta S, Murthy J, Rao A, Abraham K-.1989). Data obtained from MSCT varies – 16-section MSCT has results
closer to angiography while 64-section MSCT is closer to anatomical studies.
FIGURE NO. 26 :- SHOWING . Myocardial bridge
Myocardial bridging represents usually a benign condition with an excellent long-term survival. On the other hand, its presence has been linked to myocardial ischemia, infarction, exercise induced tachycardia, conduction disturbances and sudden death. A careful analysis of the lesion(s) is mandatory as the therapeutic approach is totally different from case, many forms of bridging have been described, the term itself does not represent a unique entity but a wide spectrum of modifications, and thus, clinical manifestations and consequences are protean. A correlation was attempted between myocardial bridging and ECG, myocardial perfusion scanning and clinical symptomatology but with limited practical significance The myocardial bridge is generally defined as a superficial muscular band that extends across short segments of the coronary arteries located subepicardially in various parts of the heart. Anatomical studies of myocardial bridges have identified the occurrence, distribution, and type of myocardial bridges in various species (Geiringer E -1951) Diffuse disease, with multiple obstructions often necessitates graft placements in recruitable less obstructed segments of the artery. Not infrequently, an intramural portion of the LAD must be exposed in order to obtain an adequately sized segment, free of disease, for bypass. Although we are aware from previous studies (Dhawan ; Bray, 1995, Vlodaver et aI., 1969, Litovsky et aI., 1996) that inter-ethnic and sex differences may exist, this study does not suggest any such differences in the prevalence ofmyocardial bridges. There is significant bank of literature regarding myocardial bridges, (Angelini et aI., 1983; Bezera et aI., 1989; Bloor and Liebow, 1965, Kosinski and Grzybiak, 2001 and Venkateshu et aI., 2000). The topic has received a fair amount of discussion, enough to have had established the general anatomy as well as the overall morphometry and arrangement of these bridges.
7.7.8. Noteworthy contributions in the field of proposed work :-
M. Trivellato, M.D., Paolo Angelini, M.D., and Robert D. Leachman, M.D. have given very important contribution in field of proposed work they have described classification of coronary artery anomalies, together with angiographic examples of each entity. Minimal requirements for normality include the following criteria:
(1) The dual aortic origin is from right and left coronary ostia;
(2) the course of the right coronary artery follows the right atrioventricular groove,
(3) The course of the left coronary artery follows the left atrioventricular groove and anterior interventricular groove,
(4) The posterior descending branch originates from either the
right or left coronary artery,
(5) The major coronary branches flow epicardially,
(6) The coronary arteries terminate at the myocardial capillary level. This conception of “normal” coronary arteries has determined the classification of abnormalities presented here.
Early and correct diagnosis of anomalies that may compromise the myocardial blood supply is stressed, and possible surgical solutions are offered. Selective coronary angiography is the technique of choice for precise visualization of the coronary artery system. Owing to the widespread practice of coronary angiography and cardiac surgery, the literature regarding the coronary artery circulation is being continually enriched. Although not all coronary artery anomalies are indicative of disease, each should be carefully examined and classified to prevent diagnostic errors. Some anomalies have a precise surgical indication, whereas others may complicate cardiac surgery or indirectly affect the natural prognosis of’ a disease. Because normal subjects reveal extreme variability in coronary artery anatomy,” a precise definition of’ normality would require statistical evaluation of all possible anatomic variations to determine a minimum common denominator. Even then, the boundaries between normal and abnormal would have to be established by empirical methods. Based on the origin, course, and termination of’ the coronary arteries, as revealed by selective coronary angiography, they have outlined certain minimum criteria for normality as described above.Table -3
8. Materials and Methods : –
In present study I have used three different techniques to study anatomical variations & anomalies of coronary arteries in their origin (ostia), dominance pattern ,branching pattern and course (myocardial bridging) 1.CADEVERIC HEART DISSECTION & X-RAY TECHNIQUE, 2. CT CORONARY ANGIOGRPHY (64-slice CT-CA), 3. CORONARY ANGIOGRAPHY TECHNIQUE
8.1.CADEVERIC HEART DISSECTION &X-RAY TECHNIQUE:-
In present study,I have analyzed Dissected 50 human hearts, which were obtained from Department of Anatomy, Gandhi Medical College Bhopal. The samples were washed thoroughly with tap water and gently squeezed to remove the blood clots from the cavity of the heart and from the lumen of the blood vessels as much as possible All specimens were Numbered from 1 to 50 with plastic token blue coloured round shaped and tied with white coloured thick thread to aorta , and were examined externally prior to the removal of the peri-vascular fatty tissue, where necessary, the epicardial course of the coronary arteries.
Figure No.27:- Showing Arrorote powder ,Sindoor , Contrast media , solution (Red coloured),injecting in coronary ostia for giving colour and contrast media to coronary arteries.
Figure No.28;- Showing injection of contrast media solution in
Figure No.29- A) Antero-lateral view of heart showing injection of contrast media.
B) showing composition of contrast & coloring media.
C)postero-lateral view of heart showing red arrow –RPDA (Right posterior descending artery, Green arrow –Acute marginal branch of RCA(Right Coronary Artery),after injection of Contrast media (Red colored).
D) Human heart showing red coloured contrast media after injection.
Figure No30 Postero- lateral view showing Right posterior descending
artery after injecting contrast coloured media.
FIGURE NO.31 SUPER-LATERAL VIEW OF HUMAN HEART SHOWING CUT LUMEN OF LAD (Left Anterior Descending Artery),LMCA (Left Main Coronary Artery), Pulmonary Trunk (PT)
FIGURE NO.32 HUMAN HEART CUT SECTION AT SINU-TUBULAR JUNCTION SHOWS CORONARY ORIFIES (PROBBED)
In all hearts, the aorta was opened by a longitudinal incision through its aortic cusps. The circumference of the valve was measured at the level of the sinotubular junction (STJ) which marked the transition from the aortic portion of the aortic trunk with dilatators. The sizes (height and width) of the three aortic sinuses at the level of the sinotubular junction were seen (Fig.No.32 ). In each specimen, the number, position, and shape of the coronary arterial orifices and the presence of accessory orifices were recorded. The vertical position of each orifice was measured in relation to the STJ and was described as either being above, below, or at the level of the junction. The radial position was measured as the distance from the orifice to the zone of apposition between the facing aortic valvular leaflets in the open position (Fig.27,28 ).After finding the origin of right and left coronary artery , coronary arteries were injected with radio – opaque solution , solution was prepared by mixing radio opaque dye with Ararote powder and sindoor , shown in (Figure No29) Ararote powder has given necessary hardness to the arteries and sindoor has given redness to the artery and radio opaque dye was used to visualize arteries in the X-Rays ,then samples were Radio- graphed then coronary arteries were analyzed specially for coronary anastomosis course and branching pattern, then peri-vascular fat was removed by dissection.
FIGURE NO 33:-. HUMAN HEART POSTERO-MEDIAL VIEW SHOWS RCA-RIGHT CORONARY ARTERY,AM-ACUTE MARGINAL BRANCH AFTER INGESTION OF RADIO OPAQUE MEDIA.
FIGURE NO.34 :-
SHOWING X- RAY OF HEART BRANCHES OF LEFT CORONARY ARTERY AFTER INJECTING RADIO-OPAQUE DYE.
Origin of coronary artery identified externally and branching pattern was traced over surface of the heart ,myocardial bridges and termination of coronary arteries has been analyzed.At the end X-Rays and dissected hearts were photographed by SONYTM Cyber shot digital camera (DSC-W320) with Steady Shot,Opticl Zoom 4x,26mm Wide –angle lense (Carl Zeiss) was used photographs were re-printed by colour printer.
8.1.1. Study of Anatomical variations in origin of coronary arteries
Arterial blood reaches the cardiac tissues via two major coronary arteries, each of which arises from the base of the ascending aorta . The locations of the coronary artery orifices in relation to the aortic sinus have been reported in several studies for the identification of these anomalies by trans-thoracic echocardiography, angiography, and autopsy . These anomalies may act as potential causes of myocardial ischemia resulting in arrhythmias, angina, or infarction especially during exercise. Although the reason of sudden fatal events is generally unclear, they may be related to the anatomical variants and the proximal course of the coronary anomaly. The great importance of coronary catheterization for diagnostic and therapeutic purposes has currently motivated several studies on the anatomical position of the coronary orifices. Yet, despite the importance of the subject, most of these case studies were observed to include insufficient data concerning the detailed parameters and frequency. The aim of our study is to determine the range in the size of the components of the aortic valve and relate this information to the anatomical pattern of the coronary arterial orifices in order to provide some data on the range of normality. In present study,I have analyzed Dissected 50 human hearts, which were obtained from Department of Anatomy, Gandhi Medical College Bhopal. The samples were washed thoroughly with tap water and gently squeezed to remove the blood clots from the cavity of the heart and from the lumen of the blood vessels as much as possible All specimens were examined externally prior to the removal of the peri-vascular fatty tissue, where necessary, to expose the epicardial course of the coronary arteries. In all hearts, the aorta was opened by a longitudinal incision above the level of aortic cusps. In each specimen, the number, position, and shape of the coronary arterial orifices and the presence of accessory orifices were recorded. The vertical position of each orifice was analysed in relation to the STJ and was described as either being above, below, or at the level of the junction. After finding the origin of right and left coronary artery , coronary arteries were injected with radio – opaque solution , solution was prepared by mixing radio opaque dye with Ararote powder and sindoor , shown in (figure No.27.) Ararote powder has given necessary hardness to the arteries and sindoor has given redness to the artery and radio opaque dye was used to visualize arteries in the X-Rays ,then samples were Radio- graphed then coronary arteries were analyzed specially for coronary origin, course and branching pattern of coronary arteries, for this purpose peri-vascular fat was removed by dissection, origin of coronary artery identified externally and branching pattern was traced over surface of the heart ,myocardial bridges and termination of coronary arteries has been analyzed.At the end X-Rays and dissected hearts were photographed by SONY Cyber shot digital camera (DSC-W320) with Steady Shot,Opticl Zoom 4x,26mm Wide –angle lense (Carl Zeiss).
The aortic valves in 50 specimens were normal and possessed three cusps. There were no significant differences between the sexes. The data for the right, non- and left coronary cusps are given in Figure 35-36 Regarding origin of coronary artery
FIGURE NO 35. IS SHOWING STJ-SINO TUBULAR JUNCTION, ORIGINS OF RIGHT AND LEFT CORONARY ARTERIES, AORTIC SINUSES AND AORIC VALVES (SEMI-LUNAR CUSPS),ASCENDING AORTA , LV-LEFT VENTRICLE, SLIT ORIGIN OF RIGHT CORONARY ARTERY, OVALE OROGIN OF LEFT CORONARY ARTERY,COMMISSURES
Figure 36 Diagram showing the sinotubular junction (top dashed line) where the tubular aorta meets the bulbar sinuses of Valsalva.
(from: Nettr’s Anatomy ,; Gensini GG. Coronary Arteriography.)
Coronary arteries in all the specimens, coronary arteries arose from the appropriate aortic sinuses, and the main right coronary orifice (RCO) and left coronary orifice (LCO) were connected to the right and left aortic sinuses, respectively (Fig. 35-36). The relation between the RCO and LCO to the SJ in each heart are shown in Table and Figure 35-36. The results of STJ to the RCO and LCO to the commissures located on the right and left of the referred orifices the distances between the coronary orifices and commissures of the aortic cusps. The left coronary artery (LCA) The LCA arose below the SJ in 58 specimens (58%). In 13 specimens it arose at the SJ (13%), and above it in 29 (29%) (Fig. 35). The distance of the LCO in relation to the attachment of left the aortic cusps at the The data concerning the diameter and the shape of the LCO are in . In about 76% of the cases (in hearts), the diameter of the LCO was greater than that of the RCO, and in 5 specimens, the diameters of the LCO and RCO were equal. No significant differences were observed between the parameters of the orifices of coronary arteries among three age groups in male. An accessory orifice was observed in 47 specimens and two accessory orifices were found in 33 specimens.
The right coronary artery (RCA) :-The RCA arose below the SJ in 78 specimens (78%) (Fig. 35), while in 13 specimens it arose above the SJ (13%) (Fig. 35), and in 9 of them it arose at the level the SJ (9%) (Fig. 35). The highest position was 2 mm above the junction, whereas the lowest was 3 mm below it. No significant differences were observed between the parameters of the orifices of coronary arteries among three age groups in any male or female subjects (p;0.05). The average distance of the RCO from the attachments of the right aortic cusps . The majority of orifices were situated either at the SJ or right below it. The data concerning the diameter and shape of the RCO are shown in figure. An accessory orifice was found in 15 specimens Fig. 35 and two accessory orifices were observed in 5 of them. coronary orifices levels were within the SJ line or are located below it.
Level of ostia (origin) with respect to sinu-tubular junction
Level of ostia with respect to sinu-tubular junction
Level of ostia Percentage (%)
Above sinu-tubular junction (2/50) 4 %
At sinu-tubular junction (8/50) 16%
Below sinu-tubular junction (40/50) 80%
Table No. 5- Showing Level of ostia with respect to sinu-tubular junction.
The analysis in this study shows that the right sinus structures have the greatest dimensions followed by the non-coronary, and the left coronary sinuses. According to this study, it can be stated that the coronary arterial orifices are not located in the center of each aortic sinus, or close to the level of the free Horizontal margin of the aortic sinus. Regarding the SJ, most coronary orifices levels were within the SJ line or are located below it. Genetic and geographic variations in the coronaries are a known fact.( Garg et al. -2000) and (Harikrishnan et al. -2002) have reported the incidence of coronary artery anomalies in angiographic studies of the Indian population. The present study describes the normal and variant anatomy of the ostia of the coronary arteries in adult cadavers of Indian origin. Aortic root :- Since the aortic root preserving methods are spreading in heart surgery, the importance of aortic root anatomy is increasing . The present study quantitatively analyzed the curvature characteristics of the acetabular cartilage surface, which have not been reported previously. Coronary orifices Previous researchers investigated the morphometric and topographic aspects of the coronary orifices by correlating them with the aortic cusps . The levels of the coronary orifices were variable; they were usually above or at the cuspal margins. These researchers found that the LCO was located below the SJ in approximately 42% of the cases, and it was observed above the SJ in 40%. They measured the average distance from the LCO to the bottom of the corresponding sinus . Former investigators reported that the RCO was located below the SJ in 60-69% of the cases and it was above the SJ in 22-28% of cases . Previous studies showed that the mean distance from the RCO to the bottom of the corresponding aortic sinus was 13.2}2.64 mm. They reported that the RCO was predominantly located below the SJ . An orifice arising one cm or more from above the SJ, which is called high takeoff, was determined as important in the genesis of turbulence, skimming of blood and sudden cardiac death . The high origin is more important when there is a single coronary artery since the height of the orifice affects the axis of the left main stem together with the right proximal segment. Accessory coronary orifice :-An accessory coronary orifice was found in the anterior aortic sinus in 74% of the cases. The most common of these anomalies were separate orifices of the anterior descending and left circumflex arteries from the left coronary artery . Another aspect that should be emphasized because of its importance in the development of collateral circulation is the presence of the accessory orifice supplying the infundibular branch of the right ventricle, which previous researchers have found in three-quarters of their specimens . Several mechanisms have been implicated as the cause of ischemia such as increased acuteness of the angle of origin, the orifice ridge, invariably present and functioning as a restraining valve mechanism, and compression of the anomalous artery by the right-left commissure of the aortic valve . Embryological studies have shown that the coronary arteries develop after aortopulmonary septation, and the distal major coronary arteries develop subsequent to the formation of arterial orifices, (Murphy ES .et.al.1977) .According to my observations, it can be stated that all the parameters follow the pattern in which the right sinus structures have the greatest dimensions followed by the non-coronary, and the left coronary sinuses. There is also a potential importance in the arterial orifice related to the middle, the left or the right third of the space between the respective commissures. The analysis in this study show that the coronary arterial orifices are not located in the center of each aortic sinus, or close to the level of the free horizontal margins of the aortic sinus, as they were represented in many diagrams. Regarding the SJ, most coronary orifices levels were within the SJ line or are located below it. It has also been observed that the diameter of the LCO is greater than that of the RCO the right conus artery did not arise from the right coronary artery always, the study of level of ostium gains importance for angiographic dye injection. If the right conus artery arises directly from the aorta it is named as third coronary artery (Schlesinger et.al.-1949). When multiple ostia are observed in the anterior aortic sinus, the most common variation observed is an accessory orifice for the right conus artery. The 3rd coronary artery usually forms an anastomosis with the likewise branch of the left coronary artery. This anastomosis lies on the distal part of the pulmonary trunk and is known as the “vieussens arterial ring”. The functional significance of this anastomosis is still under question. However, several authors have proposed that it functions as an important collateral path between the right and left
INCIDENCE OF THIRD OSTIA OR THIRD CORONARY ARTERY REPORTED BY DIFFERENT AUTHERS WHICH ARE COMPARED WITH PRESENT STUDY
Author Ostia (%)
Gray’s Anatomy (38th edition) 50%
Blake (1964) 23.50 %
Mlyazaki (1986) 36.50 %
Regi (2003) 33.80 %
Koerig (2006) 50 %
Present study 18 %
TABLE SHOWS INCIDENCE OF THIRD OSTIA OR THIRD CORONARY ARTERY-
STUDY OF THE ORIGIN OF THE CONUS ARTERY :-
The branch origin of the conus artery has been a subject of recent clinical interest. As described in the literature review, (Williams et aI., 1989) the conus artery usually arises as the fIrst branch of the RCA. The primary role of the conus artery is to supply the conus of the infundibulum, the territory of the pulmonary trunk. In its lateral course across the infundibulum, the branch is said to complete the well-known “Circle of Vieussens” by anastomosing with a corresponding branch from the LAD. Variations in the origination ofthe conus artery have been documented in this study, (FIG NO.70). In particular, the height of its origin from the RCA and its independent origin from the ascending aorta has been highlighted as a clinically signifIcant pattern when attempting successful cannulation of the right coronary ostium. Present study evaluated the artery as a constant, being present in 100% of arterial patterns studied. The conus artery arose as the fIrst branch of the RCA in 77.2%. Its origin from the RCA at the angle between the main trunk and the aortic wall was recorded in 19.2% and regarded as a high conus origin. In 2% the conus arose via a separate ostium directly from the ascending aorta (fig.no.70). A “high origin” ofthe conus artery is defined when the takeoff ofthe artery is at the angle between the ReA and external aortic wall. In this case, the orifice of the branch is separated from the RCA orifice by a thin ridge of arterial wall The incidence of high origin of the conus artery appears to be slightly greater in males (21%) than in females (16%),Independent origin of conus artery from the ascending aorta appeared to be somewhat uncommon.
Comparative incidences of an independently originating conus artery
Reference Incidence %
James, (1961) 50
Schlesinger, (1940) 51
Symmers, (1907) 38
Bianchi, (1904) 33
Kurjia, (1986) 7.6
Alexander and Griffith, (1956) 0.3
Donaldson et al., (1982) 0.15
Present Study 12
Table No.6. :- showing incidences of an independently originating conus artery.
Coronary circulation :-Dominance pattern of coronary arteries -Many anatomists have attempted to classify coronary circulation for the large variety of coronary branches, their variable course, and range of anatomical areas supplied with blood. The first classification was introduced by( Banchi et.al. – 1904). He observed the dominance of the right coronary artery in 17%, the left coronary artery in 10%, and the co-dominant type in 73% of examined hearts. Adachi et.al. introduced five coronary circulation types. In type I, normal, or co-dominant, the heart is supplied by both coronary arteries in a balanced manner and is observed in 60% of the population. This type is characteristic for primates and is defined as classical in humans. Type II is characterised by the dominance of the right coronary artery. This results from the excessive development of the posterior part of the right coronary artery, with the simultaneous involution of the circumflex branch. Consequently, the posterior wall of the left ventricle is supplied mainly by the right coronary artery. This type is observed in 20–24% of the general population, and is typical for even-toed ungulates. Additionally, Adachi et.al. described a mixed type between I and II and evaluated its frequency in the population as 10–12%. Type III is characterised by the dominance of the left coronary artery and is observed in 10–14% of the general population. (Schlesinger et.al.) claimed that if the right coronary artery runs beyond the crux cordis . Dominance can be a significant determinant of prognosis in acquired coronary artery disease. In most incidences of left dominance, the RCA is usually small and fails to reach the right margin of the heart. Consequently, an acute, proximal occlusion could have unfavourable effects as the potential for re-opening collateral channels is diminished. Surgically, the pre operative indication of dominance may have an influence in the determination of graft placement. (Nerantzis et aI., 1996) however, brings a different perspective to the issue of dominance. The authors consider that beyond the ”usual” measure of arterial dominance lies the concept of “real” dominance. They propose, that when the RCA extends beyond the crux to the left circumflex territory after having given off the PDA, the coronary system is said to be one of “real right dominance”. In this instance, the extension of the RCA is responsible for supplying the posterior papillary muscle Introduced by Schlesinger (1940), the term dominant is used to indicate the areas ofthe heart supplied by each artery. Although the left system is known to supply a greater mass of myocardium than the right, it is not usually “dominant”, (Allwork, 1987). The dominant coronary artery is that which gives rise to the posterior descending artery, coursing the posterior interventricular groove.
Table No.7. Showing A comparison of the frequency of coronary circulation types among various studies and comparision with present study. Coronary Arterial Distribution Reported by Different Investigators :
Mac Alpin 55% 9% 35%
Bergman et al. 50% 20% 30%
Vasko 48% 16% 36%
Schlesinger 48% 18% 34%
Franch et al 70% 10% 20%
Chaudhry 75.73% 11.65% 12.6%
Kronzon et al. 87% 10% 3%
Murphy et al 79% 9% 12%
Hutchins et al 70% 10% 20%
Present Study 74% 18% 8%
8.2. CT CORONARY ANGIOGRPHY (64-slice CT-CA) (Non-Invassive) : –
All CT examinations were performed retrospectively evaluated (from computer saved data) in the all procedure & are being performed by a 64-slice CT scanner (SOMATOMTM Sensation siemens medical). Patients with a heart rate greater than 75 beats/min were premedicated with an oral dose of 40 mg propronalol one hour before the scan. Sublingual nitroglycerine was delivered to the patient just before the scan. For venous access, an upper extremity vein (antecubital vein of the right arm) and a 20-gauge IV cannula was used. A total of 80–85 mL of contrast media with high iodine concentration (?350 mg/mL) was injected with a flow rate of 5 mL/s, followed by a 20 mL saline chaser. The scan timing was determined with automated bolus tracking technique by placing the region of interest over the proximal descending aorta. Image data of Coronary arteries were analized for their origin (ostia), dominance pattern ,branching pattern and course (myocardial bridging). Coronary angiography remains the current gold standard for diagnosing MB. Lower prevalence of myocardial bridging on coronary angiography may partly due to thin bridging. In addition, coronary angiography is an invasive technique with complications and risks. Until now, intravascular ultrasound (IVUS) is the most accurate method to diagnose MB. Intracoronary Doppler ultrasound (ICD) has also been used in the diagnosis of bridging. However, they are all invasive and expensive and not routinely used in clinical settings. Therefore, the need for a non-invasive technique for detection of bridging has emerged. While multi-detector computed tomography (MDCT) angiography is faster and more adequate, it has the ability to assess the course and the anatomic relationships of the coronary arteries. The prevalence varies substantially among different studies. It was higher at autopsy studies than conventional coronary angiographical studies. The incidence of myocardial bridging among postmortem studies had been reported from 5% to 86%. However, the prevalence of myocardial bridging among patients with conventional coronary angiography varied from 0.5% to 33% Based on computed topography angiography (CTA), MB can be classified as three types. Type I is myocardial bridging with partial encasement as LAD being within the interventricular groove and in direct contact with left ventricular myocardium. Type II is myocardial bridging with full encasement as LAD being surrounded by myocardium but without measurable overlying myocardium. Type III is myocardial bridging with full encasement as LAD being surrounded by myocardium but with measurable overlying myocardium . The heart is moving fast during computed tomography imaging. So it requires a higher temporal resolution and higher spatial resolution for visualization of coronary artery as well as myocardial bridging. Despite improvement of imaging acquisition of coronary artery, there is still some gap between coronary CT angiography and invasive coronary angiography. At normal condition, temporal resolution of MDCT((4-MDCT, 250 milliseconds,16-MDCT, 183– 250 milliseconds; 64-MDCT, 165–210 milliseconds) is much more lower than that of invasive coronary angiography(