Unusual Left Superior Vena Cava, Connected to the Left Atrium via the Left Superior Pulmonary Vein.

Persistent left superior vena cava (LSVC) that drains into the left atrium (LA) via the left superior pulmonary vein (LSPV) is a rare systemic venous drainage anomaly. It can cause cyanosis and unexplained recurrent strokes. Undiagnosed, it can seriously disrupt the conduct of the cardiopulmonary bypass (CPB), causing sudden air lock and/or flooding of the operative field with venous blood. Its connection with the LSPV outside the pericardium makes its intraoperative diagnosis difficult. We report here the case of a 48-year-old man operated for mitral and aortic valve endocarditis, complicating a Laubry-Pezzi syndrome. The opening of the LA was followed immediately by the entrance of high volume of air bubbles into the superior vena cava cannula which resulted in sudden air lock of the venous outflow line. After multiple lowerings and cessations of pump flow, partial clamping of this cannula resulted in flooding of the LA with venous blood coming from the LSPV. The heart luxation did not allow us to find the LSVC in its usual intrapericardial location, between the LSPV and the left appendage. We had to widely open the left pleura to expose its completely extrapericardial path and its communication with the LSPV. The LSVC was temporally clamped during the remainder of the surgical procedure, then ligated at both ends. The patient underwent mitral valve repair, closure of the infundibular septal defect, aortic valve replacement and tricuspid annuloplasty. He was discharged 10 days later.