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 of the RSVC into the LA and the absence of any atrial septal defect because contrast did not enter the RA. This RSVC anomaly on hindsight was missed on transthoracic echocardiography, which otherwise showed a structurally normal heart. After confirmation of anomalous drainage of the RSVC to the LA, the procedure was switched back through the challenging PLSVC approach. The ventricular lead was maneuvered to form a loop on the RA free wall and, with the help of reshaped stylet (L-shaped configuration), was advanced through the tricuspid orifice toward the interventricular septum. The lead was then prolapsed and positioned at the lower part of the interventricular septum, and an active fixation helix was deployed. The atrial lead was similarly positioned and screwed to the RA free wall (Figure 4A and 4B), and a dual-chamber permanent pacemaker was successfully implemented. Chest computed tomography angiogram (Figures 5A, 5B, and 6 and Movie IV in the online-only Data Supplement) confirmed drainage of the RSVC into the LA, whereas the PLSVC with a pacemaker lead in situ was seen draining into the RA via the CS.
This is an extremely rare thoracic systemic venous anomaly of the RSVC draining into the LA and PLSVC draining into the RA with symptomatic sinus node dysfunction presenting as a challenging surprise during pacemaker lead placement.
During the fourth week of gestation, a pair of anterior cardinal veins form that drain the cephalic part of the embryo and a pair of posterior cardinal veins form that drain the rest. Anterior and posterior cardinal veins join to form a short common cardinal vein (duct of Cuvier), which opens into the respective horns of sinus venosus. The proximal portions of the right anterior cardinal veins and right common cardinal vein form the RSVC. The left anterior cardinal veins normally obliterate to form the ligament of Marshall, whereas the left horn of the sinus venosus and adjacent portion of the left common cardinal vein form the CS. Persistence of the left anterior cardinal vein forms the left SVC, which always continues with the CS as the left common cardinal vein that is part of both the CS and left SVC. Flow of PLSVC blood into the CS results in its enlargement, and a dilated CS is often the first clue for the diagnosis of PLSVC during echocardiography. In 82% to 90% of cases, PLSVC is associated with bilateral SVC; isolated PLSVC is occasionally seen in association with situs inversus or dextrocardia. In the absence of any other cardiac malformation, PLSVC to the RA is an incidental finding, but it may have an impact on procedures that require left upper-limb venous access such as transvenous pacemaker lead implantation. Similarly, cannulation of the heart for cardiopulmonary bypass may result in ineffective retrograde cardioplegia. The earliest reported case in the English literature of LA drainage of the RSVC was described by Wood, and at least 18 additional cases have been published in English since then.2 It is believed that a deficiency of the wall between the RSVC and right superior pulmonary vein results in shunting of RSVC blood into the LA via the LA orifice of the right superior pulmonary vein, and if this shunt predominates in fetal life, blood flow to the RA through the RA orifice of the SVC will be diminished or completely eliminated, leading to SVC orifice atresia and eventually RSVC draining only into the LA.3 A patient with RSVC draining into the LA may present with symptoms of hypoxemia, decreased effort tolerance, cyanosis, and clubbing, depending on degree of right-to-left shunt, which was absent in our case; as greater volume of venous blood probably returns by way of the inferior vena cava and PLSVC into the RA and was normally oxygenated, thus minimizing the degree of right to left shunting. Abnormal development of the right horn of the sinus venosus and right anterior cardinal vein may jeopardize the normal development of the sinoatrial node and result in abnormal sinus node function. In the presence of PLSVC, placing a stable pacemaker lead in the RV through the CS can be difficult because the tip of the lead is deflected away from the tricuspid orifice. Reshaping the stylet tip into 3- to 4-cm-wide closed pigtail loop with U- or L-shaped bends, depending on the geometry and shape of heart, may help in maneuvering of the lead into the RV. In the absence of symptoms of right-to-left shunt in the present case, surgical diversion of RSVC blood into the RA was deferred.
The online-only Data Supplement is available with this article at http://circ.ahajournals.org/lookup/suppl/doi:10.1161/CIRCULATIONAHA.115.018898/-/DC1.
- © 2015 American Heart Association, Inc.