Histological recognition and classification of the atrioventricular node artery variants: a new approach

There is a controversy in the literature concerning the origin, course, and distribution of the atrioventricular (AV) node artery.

Postmortem coronary angiography, dissection, and microscopic examination were performed in 100 human hearts specimens, providing anatomical, histological, and postmortem angiographic features of the AV node artery.

Two anatomical types of AV node artery, depending on its length (long-short), were found. "Long-length" (LL) AV node artery supplied with blood almost all the AV conducting tissue in 72 cases. It consisted of a horizontal and descending part ending in two branches. "Short-length" (SL) AV node artery had only a horizontal part, perfusing exclusively the AV node and several times the nonpenetrating main bundle of His. In 67 of 100 cases, the AV arteries were arising from the right coronary artery, distal to the posterior descending (PD) artery. The AV node artery never originated from the PD artery. In 54 of 100 cases, it passed under the coronary sinus (CS) and in the remaining 46 it passed underneath the right atrium endocardium.

The above-described postmortem coronary angiographic findings are essential for interventional cardiologists and cardiac surgeons. Damage to the LL or SL type of AV node artery may cause severe or limited AV conduction abnormalities, respectively. Furthermore, the course of AV node artery under the CS makes it susceptible to injuries provoked by diagnostic or therapeutic procedures involving the CS area.