Length of main left coronary artery in relation to atherosclerosis of its branches. A coronary arteriographic study

Design of experiment approach to identify the dominant geometrical feature of left coronary artery influencing atherosclerosis

Background and Objective. Coronary artery geometry heavily influences local hemodynamics, potentially leading to atherosclerosis. Consequently, the unique geometrical configuration of an individual by birth can be associated with future risk of atherosclerosis. Although current researches focus on exploring the relationship between local hemodynamics and coronary artery geometry, this study aims to identify the order of influence of the geometrical features through systematic experiments, which can reveal the dominant geometrical feature for future risk assessment.Methods. According to Taguchi's method of design of experiment (DoE), the left main stem (LMS) length (lLMS), curvature (kLMS), diameter (dLMS) and the bifurcation angle between left anterior descending (LAD) and left circumflex (LCx) artery (αLAD-LCx) of two reconstructed patient-specific left coronary arteries (LCA) were varied in three levels to create L9 orthogonal array. Computational fluid dynamic (CFD) simulations with physiological boundary conditions were performed on the resulting eighteen LCA models. Average helicity intensity (h2) and relative atheroprone area (RAA) of near-wall hemodynamic descriptors were analyzed.Results. The proximal LAD (LADproximal) was identified to be the most atheroprone region of the left coronary artery due to higherh2,large RAA of time averaged wall shear stress (TAWSS < 0.4 Pa), oscillatory shear index (OSI ∼ 0.5) and relative residence time (RRT > 4.17 Pa-1). In both patient-specific cases, based onh2and TAWSS,dlmsis the dominant geometric parameter while based on OSI and RRT,αLAD-LCxis the dominant one influencing hemodynamic condition in proximal LAD (p< 0.05). Based on RRT, the rank of the geometrical factors is:αLAD-LCx>dLMS>lLMS>kLMS, indicating thatαLAD-LCxis the most dominant geometrical factor affecting hemodynamics at proximal LAD which may influence atherosclerosis.Conclusion. The proposed identification of the rank of geometrical features of LCA and the dominant feature may assist clinicians in predicting the possibility of atherosclerosis, of an individual, long before it will occur. This study can further be translated to be used to rank the influence of several arterial geometrical features at different arterial locations to explore detailed relationships between the arterial geometrical features and local hemodynamics.

Left main coronary artery morphological phenotypes and its hemodynamic properties

BACKGROUND

Atherosclerosis may be linked to morphological defects that lead to variances in coronary artery hemodynamics. Few objective strategies exit at present for generalizing morphological phenotypes of coronary arteries in terms of hemodynamics. We used unsupervised clustering (UC) to classify the morphology of the left main coronary artery (LM) and looked at how hemodynamic distribution differed between phenotypes.

METHODS

In this study, 76 LMs were obtained from 76 patients. After LMs were reconstructed with coronary computed tomography angiography, centerlines were used to extract the geometric characteristics. Unsupervised clustering was carried out using these characteristics to identify distinct morphological phenotypes of LMs. The time-averaged wall shear stress (TAWSS) for each phenotype was investigated by means of computational fluid dynamics (CFD) analysis of the left coronary artery.

RESULTS

We identified four clusters (i.e., four phenotypes): Cluster 1 had a shorter stem and thinner branches (n = 26); Cluster 2 had a larger bifurcation angle (n = 10); Cluster 3 had an ostium at an angulation to the coronary sinus and a more curved stem, and thick branches (n = 10); and Cluster 4 had an ostium at an angulation to the coronary sinus and a flatter stem (n = 14). TAWSS features varied widely across phenotypes. Nodes with low TAWSS (L-TAWSS) were typically found around the branching points of the left anterior descending artery (LAD), particularly in Cluster 2.

CONCLUSION

Our findings demonstrated that UC is a powerful technique for morphologically classifying LMs. Different LM phenotypes exhibited distinct hemodynamic characteristics in certain regions. This morphological clustering method could aid in identifying people at high risk for developing coronary atherosclerosis, hence facilitating early intervention.

Relationship between Coronary Arterial Geometry and the Presence and Extend of Atherosclerotic Plaque Burden: A Review Discussing Methodology and Findings in the Era of Cardiac Computed Tomography Angiography

Coronary artery disease (CAD) represents a modern pandemic associated with significant morbidity and mortality. The multi-faceted pathogenesis of this entity has long been investigated, highlighting the contribution of systemic factors such as hyperlipidemia and hypertension. Nevertheless, recent research has drawn attention to the importance of geometrical features of coronary vasculature on the complexity and vulnerability of coronary atherosclerosis. Various parameters have been investigated so far, including vessel-length, coronary artery volume index, cross-sectional area, curvature, and tortuosity, using primarily invasive coronary angiography (ICA) and recently non-invasive cardiac computed tomography angiography (CCTA). It is clear that there is correlation between geometrical parameters and both the haemodynamic alterations augmenting the atherosclerosis-prone environment and the extent of plaque burden. The purpose of this review is to discuss the currently available literature regarding this issue and propose a potential non-invasive imaging biomarker, the geometric risk score, which could be of importance to allow the early detection of individuals at increased risk of developing CAD.

Anatomical study of length and branching pattern of main trunk of the left coronary artery

The left coronary artery is responsible for the irrigation of important heart structures. The objective of this study was to analyze the morphological characteristics of the main trunk of left coronary artery in the Brazilian population and its clinical implications. The study was carried out by using 63 adult human hearts of the human anatomy laboratory of the Federal university of Ceará, Brazil. The hearts were dissected for exposure and analysis of the left coronary artery and its branches. The data collected were statistically analyzed. The main trunk arose from the left aortic sinus under the left atrial auricle in all the 63 hearts. The mean length of the main trunk was 8.53±4.03mm. According to the criteria for the classification of the main trunk length, about 78% were medium-sized. The majority of the hearts (52.38%) showed trifurcation of the main trunk. Anova test followed by the Tukey's post hoc test showed that the main trunk length of hearts with trifurcation was significantly longer when compared with hearts with bifurcation (9.77±4.31mm vs. 6.44±3.01mm; P=0.0029). Similar findings were observed in the main trunk length of the hearts with tetrafurcation in comparison with hearts with bifurcation (10.78±1.4mm vs. 6.44±3.01mm; P=0.0387). This study showed that there is a correlation between the branching pattern and the length of the main trunk. Additionally, we showed that the most common branching pattern of the main trunk is the trifurcation, differing from other Brazilian studies and providing additional information to professionals of cardiology, cardiovascular surgery, and radiology.

Coronary Artery Dominance and Long-term Prognosis in Patients With ST-segment Elevation Myocardial Infarction Treated With Primary Angioplasty

INTRODUCTION AND OBJECTIVES

The long-term prognostic significance of coronary artery dominance pattern in patients with ST-segment elevation myocardial infarction is poorly characterized. We investigated the prognosis of such patients according to whether they had right dominance, left dominance, or codominance.

METHODS

This was a retrospective study of 767 patients, who were admitted to hospital between 2007 and 2012 with ST-segment elevation myocardial infarction and treated with primary percutaneous coronary intervention. We determined the effect of the coronary dominance pattern on all-cause mortality and readmission for infarction, adjusting for mortality as a competing event.

RESULTS

A total of 80.9% of patients had right coronary dominance, and 8.6% had left coronary dominance. Over 40.8 months' [interquartile range, 21.9-58.3 months] follow-up, 118 (15.4%) deaths were recorded, of which 39 (5.1%) were in hospital. Mortality for right dominance, left dominance, and codominance was 7.1%, 36.4%, and 13.8% (P ˂ .001), respectively. Cause of death was cardiovascular in 7.1%, 21.2%, and 2.4%. On Cox multivariate analysis, left dominance was significantly associated with mortality (hazard ratio = 1.76; P = .02). Taking "coronary dominance" into account in prediction of risk of death improved the discrimination and calibration capacity of GRACE (Global Registry of Acute Coronary Events) scoring. At follow-up, 9.3% (71 patients) had reinfarction. On multivariate analysis, left dominance was an independent predictor of reinfarction (subhazard ratio = 2.06; P = .01).

CONCLUSIONS

In ST-segment elevation myocardial infarction treated with primary percutaneous coronary intervention, left coronary artery dominance confers a higher risk of death and reinfarction than right coronary artery dominance, and should be included in prognostic stratification.

Morphometric study of left coronary artery trunk in adult human cadavers: a study on the eastern region population

INTRODUCTION

The left coronary artery shows a wide range of morphological variations which has great clinical importance. Difficulties may occur during performance of diagnostic procedures, especially in patients who undergo evaluation of percutaneous coronary interventions or during coronary artery surgeries or prosthetic valve replacements. Even, it has been found that short length of main left coronary artery was one of the congenital factors which predisposed to the development of coronary artery disease. The aim of this work was to determine the variations in the origin, length and divisions of the left coronary artery trunk in the eastern region population of India.

MATERIALS AND METHODS

The present study was carried out on 100 heart samples which were collected from a mixed race population group from West Bengal, India, after preserving them in 10% formalin solution. While carefully maintaining all standard precautions, scientifically well-planned cadaveric dissections were done and variations were noted.

RESULTS

It was found that in all specimens, left coronary artery arose from single ostia at the left posterior aortic sinus. In about 65% cases, ostia was below or at the sinotubular junction (STJ) and in a significant number (35%) of cases, it is above the level of STJ. The mean length of the left coronary artery trunk was found to be 11.42 ± 4.98 mm. LMCA were bifurcated in 56% cases, they were trifurcated in 40% cases and they were tetrafurcated in 2% cases. The results were compared with those of other studies, which showed considerable variations.

CONCLUSION

Thus, this morphometric study done on left coronary artery trunk in the eastern Indian population will be helpful for interventional cardiologists and radiologists for avoiding inadvertent vascular trauma during diagnostic and therapeutic procedures.

The Relation between Left Coronary Dominancy and AtheroscleroticInvolvement of Left Anterior Descending Artery Origin

INTRODUCTION

Limited information is available regarding the relationship between coronary vessel dominance and atherosclerotic involvement. Rheological factors have been implicated in the pathogenesis of coronary lesions. More than 90% of the coronary blood flow enters the left coronary if it is the dominant artery. The main purpose of this study was to determine the relation between left coronary dominance and atherosclerotic involvement of left anterior descending artery (LAD) origin. In addition, the prevalence and degree of associated ischemic mitral regurgitation (MR) in these patients were assessed.

METHODS

The study included 678 consecutive patients with an indication for coronary angiography. One hundred and twenty two patients with right dominant and 61 patients with left dominant arteries were randomly selected for analysis. All demographics, risk factors, coronary dominancy and involvement, left ventricular ejection fraction (LVEF), and MR were recorded.

RESULTS

One hundred and eighty three patients (mean age of 57.7 years) were studied. The types of coronary circulation included right, left, and balanced in 78.6%, 8.9%, and 12.5%, of the patients respectively. In 64 patient with significant LAD lesions, 22 (34.9%) had ostial while the remainder had non-ostial involvement. Ischemic MR was present in 5 (2.7%) patients. There was no difference in demographics, risk factors, LVEF, MR, extent of coronary artery disease, and LAD ostial involvement between left and right dominant circulations.

CONCLUSION

In this study, left coronary dominance was not associated with atherosclerotic involvement of LAD ostium and ischemic MR.

Main trunk of the left coronary artery: Anatomic study of the parameters of clinical interest

The objective of this study was to analyze in one single series all the characteristics of the main trunk of the left coronary artery (MT) that may be of use in the diagnosis and treatment of its pathologies. One-hundred human hearts from autopsies were used. The average age of the sample studied was 63.15 years +/- 18.76 (range = 17-94 years). The heart was removed after resection of the costosternum and placed in 10% formaldehyde. With gradual separation and retraction of the myocardial fasciculi the MT was exposed. The length of the MT, the luminal diameter of the MT at its midpoint, and the luminal diameter of the left coronary orifice were measured with a caliper. The angle of division between the anterior interventricular and circumflex branches was also measured, and the number of terminal branches originating from the MT was recorded. In four cases, there was no MT and the anterior interventricular and circumflex branches originated directly from the left aortic sinus. The average length of the MT was 10.8 +/- 5.52 mm (range = 2-23 mm); the average diameter at its midpoint was 4.86 +/- 0.80 mm; and there was no significant difference noted between the midpoint diameter of the MT and the diameter of the left coronary orifice. The most frequent type of division of the MT was bifurcation (62%); in 38% of cases the MT divided into three or more branches. An average value of 86.7 +/- 28.8 degrees was obtained for the angle of division of the terminal branches of the MT (range = 40-165 degrees ). There was a positive correlation between the length of the MT and the angle of division of its terminal branches, with the longest MTs having the largest angle of division.

Influence of the Geometry of the Left Main Coronary Artery Bifurcation on the Distribution of Sudanophilia in the Daughter Vessels

Uptake of circulating albumin by the aortic wall is greater downstream than upstream of branches in immature rabbits, but the opposite pattern occurs in mature animals. We investigated the role of NO in determining these variations. Descending thoracic aortas of rabbits were cannulated using techniques that avoid depressurization, overstretching, and excessive fluid dynamic stresses at the endothelial surface. They were perfused in situ at a constant pressure and flow rate with oxygenated, protein-containing physiological buffer, with or without N w -monomethyl-L-arginine, an inhibitor of NO synthesis. Aortas were fixed 7 to 8 minutes after the addition of rhodamine-labeled albumin to this perfusate, and uptake of the tracer near intercostal ostia was measured by digital imaging fluorescence microscopy of sections through the wall. Despite the absence of pulsatile flow, blood cells, and many plasma components, patterns of transport in control experiments were the same as those occurring in vivo; uptake was greatest downstream of ostia in immature vessels and upstream in mature ones, although mean uptake was higher than previously reported. In the presence of the inhibitor, mean uptake in immature arteries was elevated threefold and the maximum tracer concentration occurred deeper in the wall, but there was no change in the fractional difference between regions. Conversely, the reverse of the control pattern of transport was observed in mature arteries exposed to the inhibitor, but there was no change in mean uptake. The reversal was almost entirely prevented by adding excess L-arginine to the perfusate and was largely stereospecific. Endogenous NO thus appears to determine the mature pattern of transport near branches and helps to maintain the barrier function of the immature wall. ( Arterioscler Thromb Vase Biol. 1997;17:1361-1368.)

Relationship between the geometry and quantitative morphology of the left anterior descending coronary artery

The well established 'systemic' risk factors for atherosclerosis can explain only half of the variability in its occurrence. To account for some of the remaining variability, it was suggested that certain geometric features of atherosclerosis-prone segments ('geometric risk factors') can increase the likelihood of disease locally through their influence on the hemodynamic environment of the vessel wall. Since this mediation might elicit early morphological changes in the artery, relationships were sought between the histomorphometry and axial geometry of the left anterior descending (LAD) coronary arteries of 15 angiographically lesion-free human hearts obtained at autopsy. Geometric variables were quantified by image processing of multiplane angiograms of the hearts, and morphometry was obtained from transverse histologic sections at 91 sites. The results show that: (1) total intimal and medial area are negatively correlated with the distance from the site to the origin of the LAD; (2) the angle of the branch immediately proximal to the site is positively correlated with most of the intimal and medial variables, and appears to have a major influence on the intima; (3) the area ratio of the immediately proximal branch is correlated primarily with medial variables; and (4) local curvature is correlated only with the maximum thickness of the intima and media. These observations suggest that there are significant relationships between arterial geometry and vascular morphology prior to the development of frank disease.

Chronic sinoatrial disorder (sick sinus syndrome): a possible result of cardiac ischaemia

Postmortem angiography was used to examine the blood vessels supplying the sinoatrial node in 25 subjects with chronic sinoatrial disorder (group 1). The results were compared with similar studies in 54 subjects who died of heart block and in whom sinus node function was normal (group 2). Although no significant lesion obstructing the blood flow to the sinus node was seen in the majority of those in group 1, there were abnormalities in seven cases, with reduced filling of the sinus node artery in five. In group 2 the sinus node artery filled normally in all cases despite major disease of the parent vessel in three. The combination of contralateral coronary artery disease with extensive atrial anastomoses was actively sought because this arrangement might predispose to a steal phenomenon. Such conditions were fully met in three cases in group 1 and two cases in group 2, and were found to a lesser extent in a further two cases in group 1 and three in group 2. Although coronary artery disease was unlikely to be the principal cause of sinus node dysfunction in most of the cases studied it was relatively common and may have been a factor in about one third. Improved survival after myocardial infarction may increase the number of patients with chronic sinoatrial disorder of ischaemic origin.

Localization of lesions in the coronary circulation

The location of coronary artery narrowings in coronary disease (CAD) is of considerable importance in assessing the mass of myocardium at risk as well as patient prognosis. The detailed distribution of coronary lesions was mapped in 302 patients with CAD who had coronary angiography for chest pain. All identifiable coronary lesions were measured manually and the site and degree of narrowing were stored in a computer-based multisegmental model of the coronary tree. A high prevalence of CAD was found in proximal vessels and especially at, or adjacent to, proximal points of branching. In the left anterior descending coronary artery, the lesions were most prevalent immediately after the first diagonal branch and at the origin of this branch. In the right coronary artery, there was a high prevalence of narrowing between the infundibular and acute marginal branches and specifically around the origin of the right ventricular branch. In the left circumflex coronary artery, there was a predilection for narrowing in and around the origin of the first marginal branch. When a ramus intermedius was present, its origin was frequently the site of narrowing.

Coronary heart disease: genetic aspects

Morbidity and mortality differences between populations, between ethnic groups and between individuals are not satisfactorily explained by the variation of risk factors. Differences in genetic susceptibility might be responsible for a part of the unexplained variation of coronary heart disease (CHD) rates. Genetic factors are also significant in determining the level of risk factors in individuals. Ample evidence links genetic factors to the levels of serum cholesterol, blood pressure and diabetes. Marked sex differences in CHD mortality also indicate the role of heredity in the development of the disease. The male:female ratio varies widely between different countries, as well as between different ethnic groups. These variations are difficult to explain by variation in environmental and behavioral differences between males and females alone. The degree of atherosclerosis in males and females varies, depending on the anatomic location of the atherosclerosis. Inherited disorders of metabolism and the variability of anatomic patterns provide additional indications of the role of genetics. The data accumulated in the Israeli Ischemic Heart Disease Study over 15 years reveal an ethnic variation of risk factors coupled with remarkably larger variation in disease rates. Patterns of incidence assessed in the national mortality data of the Israeli study and in histologic findings in the coronary arteries of infants from different ethnic groups are compatible with a hypothesis that ethnic and sex differences in early structural changes of the coronary arteries partly determine the susceptibility of the latter to the development of atherosclerosis. In conclusion, findings from our studies and the review of the evidence from genetic epidemiologic investigations indicate a significant role of genetics in determining the degree, time course and severity of the atherosclerotic process and of the occurrence of symptomatic CHD. This important role of the genetic component is relevant to preventive strategies offered as tools for reducing the burden of CHD. Research into genetic determinants of both susceptibility to atherosclerosis or clinical manifestation of CHD and individual response to preventive measures should be encouraged.

Accelerated atherosclerosis in subjects with some minor deviations from the common type of distribution of human coronary arteries

Gross dissection of the coronary arteries of 566 subjects aged 0--45 years from an unselected population sample of Bucharest revealed the presence of a similar anatomical branching pattern in 58% of cases. Starting from this common type of distribution of coronary arteries, some minor deviations were detected coexisting with a thicker intima, a more rapid onset and evolution of atherosclerotic plaques, and a more important degree of luminal obstruction. Among the 15 minor deviations described in this paper, 3 were constantly associated, 9 only occasionally associated and 3 not associated with an accelerated atherosclerosis. The most important of these atherogenic deviations was present in 29% of cases or in 1 out of every 3 or 4 subjects. In essence, these deviations consisted of an excessive increase in external diameter and length of the left coronary arterial system, coexisting with an underdeveloped right coronary arterial system, or vice versa. The atherogenic deviations from the common type of distribution of the coronary arteries seemed to represent an important genetically transmitted risk factor for coronary heart disease.

The length of the left main coronary artery: pathological features

The mean length of the LCA found by pathological (or angiographic) methods is fairly constant. This exclusively anatomical study shows no significant relationship between the length of the LCA and stenotic atherosclerosis in the LCA or the heart weight or a dominant left circumflex coronary artery or a complete His left bundle-branch block.

Short left coronary artery trunk as a risk factor in the development of coronary atherosclerosis. Pathological study

The relation between the length of the main left coronary artery and the degree of atherosclerosis in its branches was studied by postmortem examination in 204 subjects aged 20 to 90 years. The findings suggest that in cases with a short main left coronary artery the atherosclerotic lesions in the anterior descending and circumflex branches appear earlier, progress faster at higher levels of severity, and lead more frequently to myocardial infarction, than in cases with a long left coronary artery trunk. In cases over the age of 50 years, where disease is expected to have developed, it was shown that the degree of atherosclerosis in the left anterior descending and circumflex branches was inversely related to the length of the main left coronary artery. The correlation coefficients were -0-527 and -0-428, respectively, and in either case a test for zero correlations was significant (P less than 0-001). The possible changes in the haemodynamic and mechanical conditions associated with the variations of the anatomical pattern of the coronary arteries and their influence in the development of atherosclerosis are discussed. It is suggested that the length of the main left coronary artery is a congenital anatomical and possibly hereditary factor influencing the rate of development of atherosclerosis in the branches of the main left coronary artery.