Posterior sinus node artery and accessory atrioventricular node artery arising by a common origin: a case report

Right posterior sinoatrial node artery showing a pericaval course: a previously undescribed mode of termination

The left posterior sinus node artery (PSNA) originates from the posterolateral left circumflex artery, is quite common and shows more frequently a retrocaval mode of termination. In contrast, the right PSNA that arises from the terminal right coronary artery has been rarely described while information on its mode of termination is generally lacking. The PSNA courses close to the ostia of the superior pulmonary veins; hence, it may get injured during surgical or catheter ablation procedures performed for the treatment of atrial fibrillation. The left PSNA terminates retrocavally more frequently than the usual SNAs; hence, it may be at a greater risk of transection during the popular superior septal approach to the mitral valve. We present a case of right PSNA which terminated in a previously unreported course, i.e., the pericaval. Discussion pertains to the anatomic features of the PSNA that render it susceptible to the aforementioned complications.

MDCT of the S-shaped sinoatrial node artery

OBJECTIVE

The purpose of this study was to use 64-MDCT to investigate the anatomic characteristics of the S-shaped variant of the sinoatrial node (SAN) artery and to describe the clinical implications of the findings in ablative procedures involving the left atrium.

MATERIALS AND METHODS

Coronary CT angiograms of 250 patients (152 men, 98 women; mean age, 60 +/- 12 [SD] years) were retrospectively analyzed for identification of the origin, number, anatomic course, mode of termination, and S-shaped variant of the SAN artery.

RESULTS

At least one SAN artery was detected in 244 patients. The S-shaped variant was seen in 35 (14.3%) of these patients. Thirty-four of the variants (30.6% of all left SAN arteries) arose from the proximal to middle portion of the left circumflex artery (mean distance between the ostium of the left circumflex artery and the origin of S-shaped variant, 28.7 +/- 13.1 mm). The other variant (0.7% of all right SAN arteries) originated from the distal right coronary artery. The S-shaped variant was the only artery supplying the SAN in 28 (11.4%) of the patients. In patients with two arteries supplying the SAN, the right SAN artery and the S-shaped variant of the left SAN artery were seen together in seven patients. The S-shaped SAN artery (mean distance from atrial wall, 2.43 +/- 0.992 mm) had a predictable proximal course, lying in the posterior aspect in a groove between the orifices of the left superior pulmonary vein and the left atrial appendage close to the left atrial wall. The terminal segment of the artery approached the nodal tissue posterior to the superior vena cava in 22 patients, anterior to the vena cava in 10 patients, and through branches surrounding the vena cava in two patients.

CONCLUSION

The S-shaped variation of the SAN artery is common and has a characteristic anatomic course. MDCT can be used to plan surgical and catheter-based left atrial interventions in which this artery is at risk of injury.