A Clinical Angiographic Study of the Arterial Blood Supply to the sinus Node: DiscussionThe nature of the blood supply to the sinoatrial node influences the clinical expression of sinoatrial ischemia in coronary heart disease. Fainting, syncope, and cardiac arrhythmias have been described as characteristic clinical features of acute infarction because of transient ischemia of the sinus node. In our clinical angiographic study, which to our knowledge is the first to describe the incidence of atheroma of the sinus node artery, 307 of the 309 patients (99.3 percent) had angiographically normal sinus node arteries free of atheroma. The two patients with atheromatous sinus node arteries showed no evidence of sinus node dysfunction. With the exception of two other cases in whom the normal sinus node artery arose from the distal portion of a severely stenotic left circumflex artery and who showed clinical sinus node dysfunction during the acute phase of myocardial infarction, there was no correlation between the origin of the sinus artery or its anatomic variation and sinus node dysfunction. To date this is the first study to our knowledge to demonstrate this lack of correlation.

Theoretically, the possibility of sinus node ischemia is greater the farther the origin of the sinus node artery from the origin of the right or left coronary arteries. However, the presence of anastomotic vessels from various different sources in the region of the sinus node, such as the extracoronary anastomoses from the bronchial arteries, provides an anatomic possibility of protection. Certainly in our study, in 216 patients with coronary artery disease there was no evidence that the sinus node artery itself supplied collateral blood flow to obstructed or narrow arteries. buy paxil online
Surgical intervention to the right and left atrial wall during operations of the mitral valve or atrial septal defects, or insertion of a decompression catheter into this region, has increased the practical importance of knowledge of the structures in the atrium and intera-trial septum. With a detailed knowledge of the arterial supply of the sinoatrial node, proper precautions may be taken to preserve these arteries during operation. The present study, like several anatomic studies, demonstrates that the sinus node artery is a large artery originating from the right or left coronary suteries. The right sinus node artery originates in the majority of cases from the proximal portion of the right coronary artery (Fig 1), but in a few instances it arises from the distal part of the right coronary artery (Figs 2 and 3). The left sinus node artery arises in more than two thirds of cases from the proximal portion of the left circumflex artery (Fig 4) and courses through the anterior wall of the left atrium to reach the sinus node. In nearly one third of cases the left sinus node artery is posterior, originates from the posterolateral part of the left circumflex artery (Fig 5-7), and courses over the lateral wall of the left atrium between the atrial appendage and the left superior pulmonary vein ending in the sinus node area.*