Bilateral Superior Venae Cavae With Crisscross Atrial Drainage

Persistent left superior vena cava (PLSVC) is the most common thoracic systemic venous drainage anomaly, occurring in 0.5% of the general population and in ≈10% of patients with other congenital cardiac anomalies.1 Anomalous connection of the right superior vena cava (RSVC) to the left atrium (LA) is extremely rare.A 40-year-old man presented with history of recent-onset dyspnea, light-headedness, and presyncope on exertion. Physical examination revealed a baseline pulse rate of 42 bpm, blood pressure of 110/70 mm Hg with the absence of postural hypotension, cyanosis, clubbing, and room air oxygen saturation of 96%. Cardiovascular system examination was unremarkable. ECG showed sinus bradycardia, and chronotropic incompetence was demonstrated on an exercise test. A 24-hour ECG Holter showed significant sinus pauses and confirmed the diagnosis of symptomatic sinus node dysfunction, so a permanent pacemaker implantation was planned. A left upper-limb venogram showed the PLSVC draining into the right atrium (RA) via a hugely dilated coronary sinus (CS; Figure 1A and Movie I in the online-only Data Supplement). Because lead placement via the PLSVC is technically challenging, the procedure was planned via the RSVC. The ventricular pacing lead introduced through RSVC, however, went inadvertently into the left ventricle, with left ventricular pacing spikes on the surface ECG and the guidewire passed through the RSVC went into the LA and right superior pulmonary vein (Figure 2A and 2B). An RSVC venogram showed that dye injected in the RSVC was seemingly flowing into LA and left ventricle without entering the right side of the heart. Backflush of contrast in the right superior pulmonary vein also could be seen (Figure 3A and 3B and Movies II and III in the online-only Data Supplement). This confirmed the anomalous drainage …