Anatomical study on the sinuatrial nodal branch in the human coronary artery

The sinuatrial nodal branch (SANB) of the coronary artery is anatomically important as it irrigates the sinuatrial node. Past studies on the origin and route of the SANB in the human heart have produced discrepant findings. Therefore, in this study, we macroscopically investigated the origin, route, and distribution of the SANB in 293 human hearts. In addition, we examined the relationship between coronary artery dominance and the origin of the SANB. The SANB was found to have one branch in 267 specimens (91.2 %), two branches in 25 specimens (8.5 %), and three branches in one (0.3 %) specimen. The SANB originated from the right coronary artery in 184 branches (57.5 %) and from the left coronary artery (circumflex artery) in 136 branches (42.5 %). Nine SANB routes were classified, all of which were distributed in the interatrial septum except for one heart with a type R3 SANB course, which was found to extend through the muscle layer of the interatrial septum into the septum. The composition of these courses could relate to the generation of the proepicardium in the amniote.