Abstract 12999: Persistent Left Superior Vena Cava Draining Directly Into Left Atrium With Occluded Coronary Sinus: A Rare Incidental Finding

Case presentation: A 43-year-old lady with pacing induced cardiomyopathy presented for pacemaker (PM) revision to biventricular PM. Medical history included complete heart block with dual-chamber PM, supraventricular tachycardia, and ventricular septal defect repair. During the procedure, numerous unsuccessful attempts were made to access the right atrium (RA) using a deflectable catheter through the left subclavian vein. Left upper extremity venography exhibited a persistent left superior vena cava (PLSVC) suspected to be entering RA through the coronary sinus (CS). Navigation of the CS was unsuccessful. As a result, the procedure was aborted, and the patient was admitted for further cardiac imaging evaluation. Transesophageal echocardiography demonstrated an abnormal blood vessel between left atrial appendage and left upper pulmonary vein. Findings confirmed with agitated saline injection into left arm. This rang a concern for unroofed coronary sinus. Surprisingly, cardiac computed tomography angiograms and left upper extremity venogram images revealed a PLSVC draining into left atrium (LA) posteriorly. Normal anatomy of the right-sided superior vena cava (RSVC). Also, a CS atresia and coronary venous drainage to LA inferiorly. Discussion: PLSVC is a rare cardiac anomaly with estimated prevalence of 0.2% - 3% among general population. Commonly PLSVC drains into RA through expanded CS and rarely into LA through unroofed CS. Uniquely like our patient, the PLSVC drains directly into the LA with atretic CS and no interatrial communication. PLSVC is usually asymptomatic and detected incidentally during invasive cardiac procedures. Despite existence of right to left shunt, patient was maintaining normal oxygen saturation even after a treadmill stress test. Crowdedness of the RSVC with previously implanted leads is likely the reason for failed passage of the catheter to RA. Cardiac arrhythmias and paradoxical embolization were reported with PLSVC.