A study of the artrial arteries in man.

The arterial blood supply to the atria of 40 human hearts has been studied using a clearing technique which leaves the anatomy of the heart intact. The general arrangement of the atrial arteries is described. The arterial supplies to the S.A. and A.V. nodes are considered in more detail as these ar probably the most important and most consistent vessels found. In over 50% of the hearts both the S.A. and A.V. nodes were supplied from branches of the right coronary artery. In only 7% were both nodes supplied by branches of the left coronary artery. In the remainder the S.A. node was supplied by one coronary artery and the A.V. node by the other, in either combination. The actual site of origin of the S.A. nodal artery varied considerably, but the single most common site (47%) was from the first part of the right coronary artery. The second most common site was from the circumflex branch of the left coronary artery (27%). The site of origin of the A.V. nodal artery was predominatly from the terminal part of the right coronary artery (80%), the remainder being supplied from the left. Some of the relatively large atrial vessels not primarily concerned with the supply of nodal tissue are described. A nomenclature has been suggested both for these and for the nodal arteries. There were many small and variable vessels that defied classification.