Does Presence of Bilateral Superior Vena Cava Impact Transcatheter Closure of Sinus Venosus Defects?

Bilateral superior vena cava (BilSVC) is common in sinus venosus defects (SVD) and can impact transcatheter closure (TCC) as venacaval diameter is smaller.

Between 2015 and 2025, baseline characteristics, post-interrogation feasibility, procedural details, and outcomes of 33 BilSVC cases were compared with 122 single SVC controls after TCC. The interrogation balloon was 4 mm larger than the venacaval diameter in controls but matched the SVD edge-to-right atrial appendage distance measured on computed tomography in BilSVC. Children required > 16 mm stents among controls, whereas smaller diameters were allowed in BilSVC.

Feasibility post-interrogation was 87.8% in controls and 80.5% in cases; the first chosen balloon was appropriate in 68.9% and 45.5%, respectively. While the balloon was downsized in 18.9% controls, 42.4% cases needed upsizing. Success was 96.7% in controls (four embolizations) and 100% in cases. Stent diameter variation between upper and lower ends was less in controls (0.81%) than in cases (0.63%). Stent overlaps successfully managed instability observed in 9% controls and 21.2% cases. After the stenting, a small, insignificant residual shunt was noted in 66.1% controls and 42.4% cases. During a median follow-up of 27 months (1-113 months), asymptomatic stent thrombi were identified in 4.3% of controls and 15.2% of cases and were treated medically. Reintervention rates for residual shunt were similar.

Post-interrogation feasibility was lower in BilSVC, with frequent balloon upsizing despite imaging predictions. Tapered stent diameters caused instability in BilSVC, even with a long SVC anchor. Residual leak was lower, but thrombosis rates were higher, impacting thromboprophylaxis.