Contribution to the study of the sinu-atrial node in lion (Felis leo)

Abstract

The blood supply of the sinu-atrial node was examined in 5 lion hearts, they were 3 male and 2 female lions from the Fundação Parque Zoológico de São Paulo; the methods employed for that study were dissection and Spalteholz transparency. The material studied allowed the following observations. 1. The area occupied by the nodal tissue receives collateral branches from the a.coronaria dextra more frequently (3 times); that is once the ramus intermedius atrii dextri exclusively and twice the ramus proximalis atrii dextri in association with the ramus intermedius atrii dextri once and once associated to the ramus distalis atrii dextri. 2. In the other cases the sinu-atrial node blood supply depends upon the collaterals from both the coronary arteries, more precisely from the rami proximalis atrii sinistri and intermedius atrii dextri. 3. Anastomosis between collaterals of the rami proximalis atrii dextri and proximalis atrii sinistri vessels directly implied in the sinu-atrial node blood supply, were noticed once.