Persistent Left Superior Vena Cava and Absent Right Superior Vena Cava: Not Only an Anatomic Variant

INTRODUCTION: A 71 year old asymptomatic woman came for an echocardiogram because of a left bundle branch block. A much dilated coronary sinus (CS) with an entering large vessel was found along with a mild left ventricular systolic dysfunction. Cardiac Magnetic Resonance (CMR) showed a persistent left superior vena cava (PLSVC), and an absent right superior vena cava (ARSVC). PLSVC drained into the dilated CS. No other cardiac abnormalities were found. Any late Gadolinium enhancement was also not seen. PLSVC and ARSVC are associated with sinus node and conduction tissue maldevelopment and atrial arrhythmias, and thus clinical follow up is indicated. CONCLUSION: CMR is a useful addition to echocardiogram to search for further cardiac abnormalities, and outline the anatomy with precision in doubtful cases.