Absent right superior vena cava in visceroatrial situs solitus

Absence of the right superior vena cava (SVC) in visceroatrial situs solitus is rare (0.07% to 0.13% of congenital cardiovascular malformations), and little is known about the type and frequency of additional heart defects and arrhythmias. We reviewed previous publications and present 9 new cases. Based on 121 known cases, we found that this anomaly is typically characterized by: (1) persistence of the left SVC draining into the right atrium by way of the coronary sinus, and (2) left-sided azygos vein draining into the left SVC. Less constant features were: (3) additional cardiovascular malformations (46%), and (4) rhythm abnormalities (36%) that usually appeared related to the complications of old age. Since absence of the right SVC is clinically silent, its status should be assessed echocardiographically prior to invasive medical or surgical procedures. This is important to avoid various management difficulties during the following procedures: (1) implantation of a transvenous pacemaker, (2) placement of a pulmonary artery catheter for intraoperative or intensive care unit monitoring without fluoroscopy, (3) systemic venous cannulation for extracorporeal membrane oxygenation, (4) systemic venous cannulation for cardiopulmonary bypass, (5) partial or total cavopulmonary anastomoses; and (6) orthotopic heart transplantation and endomyocardial biopsies.