A Study on Anatomy and Variations of Sinoatrial Nodal Artery

Abstract

BACKGROUNDThe sinoatrial nodal artery is anatomically significant because it is the landmark for the identification of the sinoatrial node (SA node), which is the natural pacemaker of heart. Origin of the SA nodal artery is highly variable. Its close relation with the atrium may lead to iatrogenic injury and ischaemia to SA node causing arrhythmias.The aim of the present study is to assess the normal anatomy and variations of SA nodal artery by studying the number, origin, course, length and distance of its origin from the ostium of parent artery. MATERIALS AND METHODSThis descriptive study was done on 75 embalmed hearts stored in the Department of Anatomy at Government Medical College, Kottayam, during the period 2016 -2017. Any heart with clearly visible abnormalities was excluded from the study. Dissection was carried out as follows-The pericardium was stripped off. RCA, LCA and their branches to SA node were dissected from their origin to termination. The number, point of origin and course of SA nodal artery were studied. The length and distance of origin from the ostium of parent artery were measured with the help of a measuring scale. RESULTSIn the study, the artery to SA node was single in 70 hearts (93.33%). Double SA nodal artery was noted in 5 hearts (6.67%). In 60 hearts, it originated from RCA (80%), in 9 hearts from circumflex branch of LCA (12%). In one heart SA nodal artery took origin from left coronary artery, where the artery trifurcated into circumflex, left anterior descending and SA nodal. Precaval course was the most common (60%). CONCLUSIONA thorough knowledge of anatomy and variations of the artery would help cardiologists to take necessary precautions to prevent ischaemia of the SA node, atrial walls and atrial septum.