Biatrial drainage of right superior vena cava with left superior vena cava: A diagnostic conundrum.

Cardiac MRI demonstrating venous anomalies.

Cardiac MRI plays a crucial role in diagnosing systemic venous anomalies and surgical planning.

Biatrial drainage of the right superior vena cava (R-SVC) is a rare entity, with fewer than 40 reported cases., There are several anatomical considerations, but only one case with associated persistent left superior vena cava (PLSVC) has previously been reported. When the R-SVC drains into both atria, either due to an abnormal connection, malposition of the atrial septum, or a superior sinus venosus atrial septal defect (SV-ASD), it may result in a right-to-left shunt with potentially significant consequences. We herein highlight the challenges associated with diagnosis of biatrial R-SVC drainage in a patient with bilateral superior vena cava (SVC).

Case Report

Consent was obtained to report this case. A 37-year-old man with history of left temporal brain abscess due to capnocytophagia canis and strep intermedius requiring craniotomy at an outside institution 2 weeks prior presented to our emergency department with aphasia and recurrent brain abscesses prompting further cardiac evaluation. His initial electrocardiogram, radiograph of the chest, and transthoracic echocardiogram were unremarkable except for a dilated coronary sinus, suggestive of a PLSVC. Given recurrent abscesses and a dilated coronary sinus, a complete congenital heart evaluation was warranted to search for a potential right-to-left shunt.

Transesophageal echocardiogram (TEE) confirmed an enlarged coronary sinus draining into the right atrium (RA) and revealed an SV-ASD shunting predominantly left-to-right (Video 1). Partial anomalous pulmonary venous connection with right upper pulmonary vein (RUPV) draining into the R-SVC was also noted. A bubble contrast study during the TEE was conducted. Right arm injection showed bubbles in the RA, coronary sinus and left atrium (LA), providing the first clue of anomalous drainage of the R-SVC (Video 1). Left arm injection demonstrated bubbles only in the RA, suggesting an intact coronary sinus (Video 1). Cardiac catheterization demonstrated an R-SVC saturation of 79% without significant step-up in the right heart and LA saturation of 96% (Figure 1). During balloon occlusion of the proximal R-SVC, injection of contrast into the right arm revealed the presence of a 5-mm interconnecting vein allowing for drainage into the RA via PLSVC and intact coronary sinus. Retrospective review of a previously completed cardiac magnetic resonance study confirmed duplicate SVCs with interconnecting vein (Figure 2). An 11-mm R-SVC inserted into the roof of the LA but drained into the right atrium via the superior SV-ASD. There was also an anomalous RUPV connecting to the base of the R-SVC with flow directed into the LA (Video 2).

Figure 1

Schematic of anatomy with associated oxygen saturations (%), systolic/diastolic, and mean pressures (in mm Hg). RPA, Right pulmonary artery; R-SVC, right superior vena cava; PLSVC, persistent left superior vena cava; LPA, left pulmonary artery; PAPVC, partial anomalous pulmonary venous connection; CS, coronary sinus; m, mean pressure; LA, left atrium; RA, right atrium; RV, right ventricle; LV, left ventricle; IVC, inferior vena cava; dAo, descending aorta.

Figure 2

Cardiac magnetic resonance imaging demonstrating venous anomalies.

The patient was referred for surgery. At surgery, anatomy was confirmed, and the Warden procedure was performed. The R-SVC was transected above the RUPV and reconnected to the RA appendage. The SV-ASD was closed with a patch to allow the RUPV to drain into the LA (Video 2).

The patient recovered without complications and was discharged home after 5 days. The patient remains well 1-year postsurgery.

Discussion

Biatrial drainage of the R-SVC is a rare condition with potentially significant clinical implications. Patients may be asymptomatic but cyanosis, mild arterial desaturation, exertional dyspnea, pulmonary emboli, arterial thrombi, stroke, and heart failure have all been attributed to biatrial R-SVC drainage. Structural variations include anatomically correct R-SVC draining into each atria via separate channels, and an R-SVC connection to both atria in patients with intact atrial septa.2, 3, 4 Biatrial drainage with and without SV-ASDs, and stenosis at the R-SVC and RA junction have also been described.3, 4, 5 Partial anomalous pulmonary venous drainage of the right pulmonary veins is a common association, as seen in our case. An accurate diagnosis before surgery often requires cross-sectional imaging.1, 2, 3, 4

We describe a unique case of a patient with recurrent brain abscesses and bilateral SVC. Due to unexplained recurrent brain abscesses and dilated coronary sinus, an extensive search for an intracardiac shunt was initiated. In our case, the R-SVC inserted into the LA but biatrial drainage resulted due to shunting across the superior SV-ASD. Correct diagnosis required persistence, familiarity with this entity, and a high degree of suspicion as initial transthoracic echocardiogram only hinted of a PLSVC and the catheterization data demonstrated no significant intracardiac shunt. The fascinating bubble contrast study, in which subsequent arm injections demonstrated bubbles in contralateral atria, however, suggested the presence of an intracardiac shunt. The final diagnosis was confirmed upon retrospective review of the cardiac magnetic resonance study while keeping in mind the TEE and bubble study findings.

In conclusion, a high degree of clinical suspicion plus optimal imaging is necessary to make the diagnosis of biatrial R-SVC drainage. A thorough evaluation with cross-sectional imaging may allow for accurate diagnosis and precise surgical planning.