The morpho-clinical correlations of coronary arteries branches and their intramural pathway

Abstract

CONCEPTUAL RESEARCH BENCHMARKS. The research actuality. The term "myocardial bridge" means a situation when a part of the coronary artery with a typical subepicardial course is covered over a certain length with a stripe of myocardium, falling into the variants of the intramural trajectories of the arteries of heart [1–3]. This part of the artery can undergo a local systolic compression of varying degrees [4]. According to autopsy studies, the myocardial bridges are found in up to 85% of cases [2.5–7]. In coronary angiography, their incidence varies considerably from author to author, being seen motionless in 0.5-30% of cases [3, 8–11], and when applying provocation tests - in 40% of cases [12, 13]. In patients with hypertrophic cardiomyopathy, complete myocardial bridges are detected in up to 40% of performed diagnostic coronary angiography [1]. Although the vast majority of the myocardial bridges are considered as benign anatomical variants, there is an extensive bibliographic material about the active role of myocardial bridges in the appearance of angina pectoris, spontaneous under the bridge coronary dissection [14], tachycardia and ventricular fibrillation [8, 15–18], transient atrioventricular block, rupture of the interventricular septum caused by myocardial ischemia [19, 20], clinical and paraclinical pattern specific to Takotsubo cardiomyopathy [5, 21]. Of special interest are the reports on the involvement and influence of thick myocardial bridges in the occurrence of acute heart attacks without an associated obstructive coronary artery disease (MINOKA), by the myocardial infarction, under- or proximal to the bridge coronary thrombosis or prolonged coronary spasm [22–24], sudden death of young people caused by major physical exertion, with the intact coronary arteries [25] - especially in cases of high-performance athletes [15] or children suffering from hypertrophic cardiomyopathy [13]. A special attention is paid to the predisposition of large branches of the coronary arteries with an unusual intramural trajectory to be affected or to cause the appearance and evolution of atherosclerotic lesions in various segments of them [26, 27]. The published research reports show the existence of a series of ambiguities and contradictory data about the macro- and microscopic structural features of the variants of the intramural trajectory of heart arteries, classification, etiopathogenetic causes of cardiac ischemia induced by myocardial bridges, their age dependence, gender, coronary type of vascularization, constitutional type, methods of diagnosis and treatment of symptomatic myocardial bridges [28.2]. The problem of the intramural trajectory of the coronary vessels is not limited to the myocardial bridges, being involved in different variants of musculovascular correlations - complete, incomplete myocardial bridges, myocardial tunnels. The purpose of the research. Evaluation of morpho-functional features of variants of atypical intramural trajectory of coronary arteries. [...]