Terminal branching pattern of the right coronary artery in left-dominant hearts: a cadaveric study

Clinical Significance of Coronary Arterial Dominance: A Review of the Literature

Coronary dominance describes the anatomic variation of coronary arterial supply, notably as it relates to perfusion of the inferior cardiac territories. Differences in the development and outcome in select disease states between coronary dominance patterns are increasingly recognized. In particular, observational studies have identified higher prevalence of poor outcomes in left coronary dominance in the setting of ischemic, conduction, and valvular disease. In this qualitative literature review, we summarize anatomic, physiologic, and clinical implications of differences in coronary dominance to highlight current understanding and gaps in the literature that should warrant further studies.

Topologic and Hemodynamic Characteristics of the Human Coronary Arterial Circulation

Background

Many processes contributing to the functional and structural regulation of the coronary circulation have been identified. A proper understanding of the complex interplay of these processes requires a quantitative systems approach that includes the complexity of the coronary network. The purpose of this study was to provide a detailed quantification of the branching characteristics and local hemodynamics of the human coronary circulation.

Methods

The coronary arteries of a human heart were filled post-mortem with fluorescent replica material. The frozen heart was alternately cut and block-face imaged using a high-resolution imaging cryomicrotome. From the resulting 3D reconstruction of the left coronary circulation, topological (node and loop characteristics), topographic (diameters and length of segments), and geometric (position) properties were analyzed, along with predictions of local hemodynamics (pressure and flow).

Results

The reconstructed left coronary tree consisted of 202,184 segments with diameters ranging from 30 μm to 4 mm. Most segments were between 100 μm and 1 mm long. The median segment length was similar for diameters ranging between 75 and 200 μm. 91% of the nodes were bifurcations. These bifurcations were more symmetric and less variable in smaller vessels. Most of the pressure drop occurred in vessels between 200 μm and 1 mm in diameter. Downstream conductance variability affected neither local pressure nor median local flow and added limited extra variation of local flow. The left coronary circulation perfused 358 cm³ of myocardium. Median perfused volume at a truncation level of 100 to 200 μm was 20 mm³ with a median perfusion of 5.6 ml/min/g and a high local heterogeneity.

Conclusion

This study provides the branching characteristics and hemodynamic analysis of the left coronary arterial circulation of a human heart. The resulting model can be deployed for further hemodynamic studies at the whole organ and local level.

Anatomy of the coronary arteries in fetal pigs: comparison with human anatomy

In this study, 94 fetal pigs were used to comprehensively investigate the origins, number, location, and distribution of the coronary arteries to enrich knowledge on the coronary circulation in fetal pigs, and allow comparison with adult pigs and humans. In fetal pigs, the posterior interventricular sulcus branch always arose from the right coronary artery and the circumflex artery was rarely extended to the posterior interventricular sulcus, while it is variable in humans. In fetal pigs, there was sometimes anastomosis (8.5%) between the left and right conus branches as nutrient arteries of the pulmonary cone. Other branches were not significantly different between fetal pigs and humans, including the acute marginal branch, obtuse marginal branch, and sinoatrial nodal artery. Coronary dominance was also similar. In conclusion, compared with adult pigs, dissection of the coronary arteries in fetal pigs provided a more faithful overview of the porcine coronary circulation. The coronary arteries in fetal pigs were also more suitable for comparison with humans when pigs are used as experimental animals for studying the coronary vessels, which could be an important reference for investigation of clinical treatment of the coronary arteries. In summary, our data provide reliable information about the distribution and ramifications of the coronary arteries, and could be useful for clinicians and surgeons who wish to comprehensively understand coronary anatomy.

Accuracy of exercise tolerance test in the diagnosis of coronary artery disease in patients with left dominant coronary circulation

Background

Exercise is a physiologic stress that helps the physicians to clarify the presence or absence of cardiovascular disease which may be obscure at rest. Although it is sensitive, its specificity is affected by several parameters, such as some metabolic conditions, some structural heart diseases, and some baseline electrocardiogram abnormalities. Currently, the relationship between coronary dominance and accuracy of EET is not examined. Therefore, this study was conducted to determine the potential impact of coronary dominance on the accuracy of EET.

Methods

In this retrospective study, data were gathered from 720 patients from four medical centers. The pattern of dominancy was determined, and the coronary dominance pattern of the patients who had normal angiograms despite abnormal EETs was compared to that from all the patients.

Results

Among the patients who had a normal angiogram despite an abnormal EET, 27% were left dominant while the frequency of left dominancy in the whole population of the study was only 10.9% (P = 0.013). There were no significant differences in baseline characteristics, such as age and sex, between the two studied groups.

Conclusion

The results indicated that the presence of left dominance in patients who had normal angiograms despite an abnormal EET was significantly higher than general population. Therefore, left dominance may be considered a confounding factor for EET, producing false positive results.