Are bilateral superior vena cavae a risk factor for single ventricle palliation?

Background: Performing superior vena cava-to-pulmonary artery anastomosis, in the presence of bilateral superior vena cavae, can be technically challenging. Our clinical observation has been that bilateral superior vena cavae are a risk factor for poor outcome in children needing single ventricle palliation.

Methods: Detailed operative, angiographic, and follow-up data were analyzed in 39 children undergoing bilateral cavopulmonary anastomosis (b-CPA). Overall outcome was compared to 274 children having a unilateral cavopulmonary anastomoses (u-CPA).

Results: Nine patients (23%) with bilateral superior vena cavae were found to have thrombus in the cavopulmonary circulation after the b-CPA. Postoperative mean arterial oxygen saturation was significantly lower in those who had thrombus [69%+/-10% versus 82%+/-7%, (p < 0.01)]. Thrombus formation was associated with mortality. The indexed superior vena cavae size was not a risk factor for thrombosis. In follow-up studies the connecting pulmonary artery segment between the two cavopulmonary anastomosis was smaller than the pulmonary arteries adjacent to the hilum. Survivors of a b-CPA were less frequently converted to a Fontan circulation at 5 years of follow up (Kaplan-Meier 5-year estimates, 39% for b-CPA versus 74% for u-CPA [p = 0.02]).

Conclusions: Bilateral superior vena cava-to-pulmonary artery anastomosis is associated with an increased risk of thrombus formation and unfavorable growth in the central pulmonary arteries. Modifications of surgical technique may alter flow patterns, thereby optimizing growth and diminishing the risk of thrombus formation. Anticoagulation therapy may be an important adjunct in children undergoing a b-CPA.