THE ARTERY OF THE SINUATRIAL NODE - ANATOMIC CONSIDERATIONS BASED ON 45 INJECTION-DISSECTIONS OF THE HEART

The origin, course and mode of termination of the artery of the sinuat rial node was studied in 45 anatomic specimens by injection-dissection . It was solitary in 88.89% of the cases and double in 11.11%. It aros e from the right coronary a. in 64.45% of cases, from the left coronar y a, in 24.44%, and from both in 11.11%. The side of origin was not si gnificantly influenced by the coronary dominance. When it arose from t he right coronary a., the course of the sinuatrial a. varied greatly w ith its site of origin from the coronary vessel, either from an atrial a. or from one of its collateral branches, and also depended on its r elations with the interatrial septum. When it arose from the left coro nary a., its course was relatively uniform, except for arteries arisin g from the inferior atrial aa., which characteristically involve the p osterior wall of the left atrium. Three modes of termination were foun d: precaval, retrocaval, and in a pericaval arterial circle. These obs ervations made it possible to understand the possible origin of disord ers of rhythm observed following disturbance of the arterial supply to the sinuatrial node during certain stages of cardiac surgery, particu larly during atriotomies and the surgical correction of certain valvul ar disorders and congenital malformations, which expose the a. of the sinuatrial node.