RESUMEN
Since the initial description of the sinuatrial node and its vascularization, numerous studies have shown the importance of the sinuatrial nodal branch (SNA). In this work, we examined the anatomy of this atrial branch using cineangiography. We reviewed the records of 100 cineangiocoronariographies done between October 1991 and November 1992 in the teaching hospital of the Faculty of Medicine of Triângulo Mineiro. The records of patients with artificial pacemakers or who had undergone cardiac surgery were not included. All the records showed left anterior oblique and right anterior oblique projections of both coronary arteries. In 65 por cento of the cases, the SNA occurred as a branch of the right coronary artery, and in 33 por cento it derived from the left coronary artery. Double irrigation of the sinuatrial area was seen in 1 por cento of the cases, and in 1 por cento of the cases the SNA originated from the aorta. In 76.9 por cento of the cases, the branch was of the medial anterior type and became less frequent in the distal part of the coronaries. There were no significant sex-related (χ2 = 0.0092), or racial (χ2 = 0.1241) differences. These finding were similar to those of studies based on anatomical or angiographic approaches. We conclude that the SNA can arise from any coronary artery, with no single, specific origin, and that there are no gender or race-related differences in this pattern.