Clarifying the anatomy of the atrioventricular node artery.

BACKGROUND: Reports of conduction abnormalities necessitating permanent pacemaker implantation due to atrioventricular node artery injury and increasing evidence of stenosis of the atrioventricular node artery in cases of sudden death are of unsolved clinical importance. Unfortunately, technical issues associated with physical and virtual dissections of the atrioventricular conduction axis make it difficult to accurately assess its arterial supply.

METHODS: We used a specialized dissection technique to gather anatomical information on the atrioventricular node artery and described them using attitudinally appropriate terminology.

RESULTS: The mean number of atrioventricular node artery branches was 1.6 in 103 submacroscopic examinations and 2.3 in 17 histological reconstructions. The artery had 5 origins in the modified AHA anatomy guidelines: distal RCA (#3), 10.4%; right posterior interventricular artery (#4PI), 7.3%; proximal RCA posterolateral branch (proximal #4PL), 76.8%; distal RCA posterolateral branch detouring the coronary sinus (distal #4PL), 1.8%; distal LCX (#13), 3.7%. Histological examination revealed that most atrioventricular node arteries immediately left the distal compact node (71.8%), suggesting that they supply mainly the proximal part of the AV conduction axis. The artery to the atrioventricular node tended to originate from the medial and atrial aspect of RCA posterolateral branch, and supplied adjacent structures within the inferior pyramidal space before entering the compact atrioventricular node.

CONCLUSIONS: Based on the visualisation of the atrioventricular conduction axis and its arterial supply, we herein provide the 'gold standard' for understanding the origin, course and distribution of the artery to the atrioventricular node.