A 70 year old woman with a history of COPD was admitted through the Emergency Room for atrial fibrillation with a rapid ventricular response. The patient spontaneously converted to sinus rhythm but reported progressive symptoms of dyspnea. A CT of the chest was performed to determine possible pulmonary etiologies to explain the patient’s symptoms.
A CT scan of the chest with intravenous (IV) contrast was performed with an IV line placed in the left antecubital fossa. Images revealed contrast draining from the left subclavian vein into a persistent left superior vena cava (SVC). The left SVC passed anterior to the aortic arch and lateral to the pulmonary artery and drained directly into the left atrium. Contrast was noted in the left atrium and left ventricle but not in the right cardiac chambers. The left atrium was dilated. There is no evidence of contrast passing from the left heart chambers to the right heart chambers to suggest an atrial septal defect.
A left superior vena cava (SVC) is the result of persistence of the left anterior cardinal vein. Ninety-two percent of left sided SVC's drain into the right atrium (usually via the coronary sinus), with the remainder draining directly into the left atrium.
A left SVC that drains into the left atrium represents a right-to-left shunt. Most patients are asymptomatic, but right heart failure, paradoxical cerebral embolism, cerebral abscess and cyanosis have been reported.
Left SVC's draining into the left atrium can be associated with complex congenital anomalies, such as the coronary sinus and atrial septal defects. However a left SVC may be seen with or without this complex set of anomalies.
In symptomatic patients, there are four methods of surgical repair reported for this congenital anomaly. They include division and reimplantation of the left SVC to the right atrium, creation of an intraatrial baffle (to divert flow from the left SVC to the right atrium and to close the atrial septal defect), simple ligation of the left SVC and anastomosis of the left SVC to the left pulmonary artery.