Anatomical observation of the sinoatrial node artery of the cardiac conduction system in adult humans

Abstract

BACKGROUND: Anatomical investigations of atrial blood vessels are limited. Knowledge of the anatomical variants of the sinoatrial node artery is important to enhance cardiac surgery and elucidate the pathogenesis of supraventricular arrhythmias. AIM: To explore and clarify the number, variants, location, and course of sinoatrial node arteries in the heart of middle-aged and older individuals. MATERIALS AND METHODS: In 62 formalin-fixed hearts of humans who died from noncardiac causes, the sinoatrial node arteries were dissected and measured using an electronic caliper. Histologically, the location of the artery into the sinoatrial node was clarified through hematoxylin and eosin and Masson trichrome staining. RESULTS: The number of sinoatrial node arteries varied from 1 (86.6%) to 3 (1.7%). Commonly, sinoatrial node arteries arose from the right coronary artery (66.7%) between the aortic root and right atrial appendage or from the proximal part of the left circumflex artery (28.3%). Rarely, sinoatrial node arteries originated from the orifice of the right coronary artery, from the left coronary artery bifurcation, and on the diaphragmatic surface of the heart from the distal parts of the right coronary artery or left circumflex artery. Sinoatrial node arteries appeared to have subepicardial and intramyocardial components. The sinoatrial node artery that originated from the right coronary artery traveled mainly subepicardially; however, the sinoatrial node artery from the left coronary artery showed a predominantly intramyocardial course. The diameter of the sinoatrial node artery that originated from the right coronary artery varied from 0.7 to 2.8 mm and that from the left coronary artery system varied from 1.1 to 2.5 mm (median, 1.7 mm; p=0.96). The right coronary artery and sinoatrial node artery that branched from that formed a correlation pair in diameter values (Rs=0 .44; р=0.005). CONCLUSIONS: The sinoatrial node artery has common and rare variants, which differ in the number, origin, and topography of the artery.