The results of this study confirmed the standard anatomical description of the coronary arteries as documented. Results of the histopathological examination (n=20) indicated the presence of atherosclerotic disease within the intramural LAD artery segment (15%).
Figure NO Branches of the left coronary system in a left anterior oblique view, 50 (Adapted from Electro Medica, 2000).
LIST OF TABLES
LIST OF GRAPHS
Grapb20 Degree of atherosclerosis on the premural LAD artery segments 229 Grapb 21 Degree of atherosclerosis on the intramural LAD artery segments 230 Grapb22 Degree of atherosclerosis on the postmural LAD artery segments 230.
LIST OF PLATES
Premural LAD (3) arterial segment showing intimal hyperplasia Intramural LAD (3) arterial segment showing intimal hyperplasia Premural LAD (4) arterial segment showing intimal hyperplasia Intramural LAD (4) arterial segment showing no signs of intimal hyperplasia . Postmural LAD arterial segment (4) showing no signs of intimal hyperplasia. The LAD intramural arterial segment shows an extensive surrounding layer of adipose tissue.
LIST OF ABBREVIATIONS
INTRODUCTION
INTRODUCTION
It may seem presumptuous for someone to decide to study the anatomy of the coronary arteries. Examination of the anatomy of the coronary arteries by means of cadaveric dissection and angiographic analysis.
CHAPTERII
LITERATURE REVIEW
CORONARY ARTERY NOMENCLATURE
The left circle, (LCX) gives off sharp marginal branches and when dominant, the posterior descending artery, (PDA). SA and AV nodal arteries SA and AV nodal arteries SA and AV nodal arteries Nodal arteries Left coronary artery Left main artery Left coronary artery.
CORONARY ARTERY ORIGIN
Their size depends on the caliber of the right marginal artery and can sometimes be absent (Williams et al., 1989). Its presence in the left coronary system depicts a trifurcation pattern in the termination of the LeA. However, this view is useful for distinguishing the diagonals of the septal perforators of the LAD (Rodriquez and Robbins, 1965), (Figure 29).
The atrial branch can be seen passing to the right and posteriorly, with some visualization of the SA nodal branches. The main trunk of the LCA can be identified via the points of origin of the LAD and LCX in the right anterior oblique projection.
ANOMALIES OF INTRINSIC CORONARY ARTERY ANATOMY
Such a pattern may result from a proximal anterior descending artery or a redundant aortic ostium, resulting in a single large first septal branch that produces most of the secondary branches, leaving a small or absent mid-distal subepicardial LAD. Alternatively, a highly dominant ReA may cause the majority of branches to form, thereby reducing the contribution of the LAD. In this way, the LAD can even reach the anterior part of the right ventricular cavity.
The second originates in the middle of the RCA, near the acute border of the heart and reaches the distal posterior part of the interventricular groove. Although this anomaly is of anatomical interest, it may become clinically significant should surgical manipulation of the posterior descending artery become necessary.
ANOMALIES OF TERMINATION
Early literature reports, (Baroldi, 1966), indicate two types of communication that exist under normal conditions in the human heart and that serve as alternatives to normal drainage in the coronary venous system. Less frequently, in otherwise normal hearts, a coronary fistula may drain into an extracardiac structure such as the pulmonary artery and its main branches or the superior vena cava. That interarterial anastomoses exist between branches of the coronary arteries in the ischemic heart is well established (Fulton, 1965).
However, their existence and functional significance in the normal heart has been the subject of repeated debate in the past. Today, the general acceptance of their existence has been embraced by interventional cardiology advances, which exploit the auxiliary capacity of the collateral circulation.
HISTORICAL OVERVIEW
Deeper communications connect the superficial arteries with the sub-endocardial plexus of the right and left ventricles at the apex. A network of channels in the deeper zone of the left ventricle forms a sub-endocardial plexus. The sub-endocardial plexus of the right ventricle is less prominent than the left.
These vessels, often found at the base of the papillary muscles, measure up to 300 microns. Intramural communications in the left ventricle, apart from septal vessels and those of the sub-endocardial plexus, are not frequently found and are almost never of large caliber.
KUGEL'S ARTERY
The right wing of the "Y" is inserted into it, the aortic tip of the mitral valve. Initially, it forms a simple anastomosis between the LCX or its branches and the posterior part of the RCA and its branches. In the second, it forms a simple anastomosis between the LCX or its branches and the anterior part of the RCA and its branches.
In the third, it is represented by diffuse anastomosis between branches from the anterior parts of the LCX and RCA and the posterior part of the LCA. Kugel's artery also shares a close connection with the posterior and left lateral surfaces of the aorta.
THEBESIAN VESSELS
Furthermore, he explained the absence of infarcts in markedly sclerosed hearts by the presence of the Tebesian circulation. He believed that the "sinusoidal" circulation of the embryonic heart was sufficient to nourish the trabecular muscle. Wearn (1928) postulated that the existence of the Tebesian vessels, "being the only other entrance to the coronary circulation," was responsible for the nutrition necessary to maintain the myocardium.
This persists in the arrested heart, "despite adequate ventilation of the left ventricle and decompression of the coronary sinus to prevent retrograde flow" (Brazier and Hottenrot, 1974). Langer (1880) described branches of the coronary arteries that anastomose with vessels in the mediastinum, parietal pericardium, diaphragm, and hila of the lungs.
ANATOMY OF EXTRA-CORONARY COLLATERALS
Larger, more numerous vessels are located around the mouths of the vena cavae, tightly attached to the adventitia. They usually consist of two large branches from the proximal RCA that develop around the mouth of the vena cava after supplying the wall of the ear. The vessels communicate with the pericardial branch of the internal thoracic arteries, as well as with the small anterior branches of the thoracic aorta.
However, the main anastomoses of the pericardial vessels with the coronary arteries appear to be in the region of the pericardial ostia of the pulmonary veins and vena cavae. These vessels are small anterior branches of the thoracic aorta and freely anastomose with the bronchial, phrenic, and intercostal branches of the internal thoracic arteries.
CORONARY ARTERIES: AGE INFLUENCE
At this stage, vagrant branches to the adipose tissue can be observed in the coronary furrows parallel to the main arteries. From i h to the 8th and especially in the 8th decade it shows the complicating feature of arteriosclerosis. He attributes this characteristic to the histological deterioration of the vessel wall and relative shrinkage and eventual atrophy of the myocardium in the later decades of life.
The use of angiography in the visualization of intramural arteries was first introduced in 1960 by Portsmann and Iwig. Systolic narrowing patterns of the LAD artery were also observed in patients with systolic overload, especially in the presence of hypertrophic cardiomyopathy (16%) and in about 11 %, indicative of tfiyocardial.
CORONARY ARTERIES: ETHNICITY AND SEXUAL DIMORPmSM
- HISTOLOGIC FEATURES OF THE NORMAL CORONARY ARTERY
The results of their study showed that coronary artery dimensions showed a significant correlation between body size, heart weight and age, and that vessel size increased with age. According to Likoff et al., (1972) this arrangement, combined with the somewhat "loose" consistency of the adventitia, influences changes in the diameter of the coronary arteries. As for the coronary arteries, this disease can involve the entire epicardial length of the vessel.
It is commonly seen in the PDA, the distal branches of the LAD and terminal diagonal branches and also in the LCX system. Much consideration appears to have been given to the branching pattern and length of the left main trunk in terms of lesion distribution.
CHAPTERIII
MATERIALS AND METHODS
ANATOMICAL INVESTIGATION
- HARVESTING OF POST MORTEM AND CADAVERIC HEARTS
- INJECTION PROCEDURE
- DISSECTION PROCEDURE
- MORPHOMETRIC ANALYSIS
The sternal plate was removed by separating the sternoclavicular joint and each costochondral junction. The main trunk of the LCA was palpated at the left coronary sinus with lateral separation of the pulmonary trunk and left atrial appendage. Dissection was continued along the inferior plane along the length of the LAD using deliberate outward movements of the scissors.
To prevent unnecessary damage to the underlying myocardium, blade movements were limited to the direction of the fascial fibers in the plane. The alternative dissection approach involved locating the LCX at the posterior interventricular groove and then dissecting along the course of the artery within the coronary groove.
The length of the LCA
The adventitia and epicardial fat were then removed to expose the left main trunk. In the first approach, the artery was traced from its origin within the "pulmono-auricular" fossa and exposed to its endpoint. The coronary arteries of each heart were examined under magnification and the following noted:
The termination pattern of the LCA
Origin of the LAD and LCX
Presence and anatomy of the ramus marginalis artery
Measure of arterial dominance
The path taken by the LeX
The branching pattern of the LAD
- ANGIOGRAM SELECTION AND ANALYSIS
- INVESTIGATION OF MYOCARDIAL BRIDGES
- ANGIOGRAPHIC ANALYSIS
- CADAVERIC INVESTIGATION
- INVESTIGATION OF THE EXTRA-CORONARY COLLATERALS
- SPECIMEN SELECTION
- LABORATORY EQUIPMENT
- INJECTION PROCEDURE
In each case, the position of the LAD was recorded as described during surgical presentation. In each case, the appearance of the LAD was examined on the angiogram, first by direct observation and second based on a measure of its "degree of rightness". 34 The “LCA-LAD” segment was selected and the point of origin of the first septal perforator was marked.
A 4-5 mm Thru-Lumen Fog ~ embolectomy catheter was used for the infusion of the injection material. A confirmatory test was performed to compare the degree of radiotransparency of the substances used according to standard investigations.
Test for radio-opacity of selected injection media against soft tissue
- Location and Cannulation of Coronary Ostia
- Gross Inspection and Dissection
- Morphometric Analyses by Micro-Dissection
Filling of the coronary tree was observed fluoroscopically, and radiographs were taken from antero-posterior, right and left oblique, and lateral views. The sternum was removed, leaving the internal thoracic arteries on the surface of the fibrous pericardium. The right and left antero-lateral quadrants of the chest were removed to create wider access.
A longitudinal incision in the posterior wall and to the left of the fibrous pericardium allowed access to the esophageal area. Histology of the coronary arteries was limited to an evaluation of the pathological status of the LAD in relation to its myocardial position.
CHAPTERIV
RESULTS
SAMPLE DISTRIBUTION
The sample comprised 212 angiograms and 95 cadaver dissections of hearts obtained in the South African cohort and 16 fresh tissue dissections of hearts obtained in the North American cohort (Graph 1). The first data set (n = 83) was obtained from postmortems within the South African population and included sex, age, ethnicity and height.
GROSS ANATOMY Coronary Artery Origination
Aortic sinuses and coronary artery origination
The PDA was recorded as a branch of the RCA arising near the crux in 80.7%. The conus artery was constant and maintained an anastomosis of the rmg with the corresponding left branch around the proximal infundibular trunk. Its origin from the RCA at the angle between the main trunk and the aortic wall was recorded in 19.2% and is considered a high conus origin.
Angiographic demonstration of the RCA
The ramus marginalis descended along the obtuse margin of the left ventricle and ended approximately in line with the middle third of the LAD. Myocardial bridges were recorded over the proximal third of the LAD in 21.4%, over the middle third in 80.9% and distal third in 11.9%. In the bifurcation pattern of termination of the LCA, the left division was identified as.
As the LCX moved laterally from its site of origin, it adhered to the inferior surface of the left atrial appendage by means of a film of epicardial tissue. The average length of the LCA recorded for males was 0.96cm and 0.84cm for females.
Anterior view of the LAD and ReA
Antero-lateral view of the LCA system (A: LAD, B: diagonal branch, C: LCX)
Right lateral view of the ReA (B) and its conus branch (B)
Anterior view of the LAD within the inter ventricular groove
Posterior view of the PDA with absent posterior LeX artery
Anterior view of the ReA (A) and ventricular branch (B) in the right atrio-ventricular groove
Posterior course of the ReA indicated by a curved arrow
