Acute effects of embolizing systemic-to-pulmonary arterial collaterals on blood flow in patients with superior cavopulmonary connections: A pilot study

Background-The significance and optimal treatment of systemic-to-pulmonary arterial collateral (SPC) vessels in single ventricle patients are poorly understood. The acute efficacy of SPC embolization has not been demonstrated in a quantifiable fashion. We sought to assess the acute efficacy of SPC embolization on blood flow as quantified by phase contrast magnetic resonance imaging and hypothesized that embolization acutely decreases SPC flow and increases systemic blood flow (Q_S). Methods and Results-Six superior cavopulmonary connection patients underwent SPC flow quantification by phase contrast magnetic resonance imaging, including quantification of superior and inferior caval, total pulmonary artery, total pulmonary vein, ascending and descending aortic flows (Q_SVC, Q_IVC, Q_PA, Q_PV, Q_Ao, and Q_Dao, respectively), both immediately before and after cardiac catheterization with coil and particle embolization of angiographically evident SPC vessels. All studies were performed under a single anesthetic. After embolization, we found a significant decrease in SPC flow of 0.9 (range, 0.6-1.3) L/(min·m²) (P=0.03); a median reduction of 47% (range, 32-60). There was a significant decrease in the median Q_P:Q_S from 1.3 before to 0.8 after embolization (P=0.03), and an increase in Q_S from a median of 3.4 to 4.4 L/(min·m²) (P<0.05), and Q_SVC from a median of 1.7 to 2.3 L/(min·m²) (P=0.03). Conclusions-We report on the acute efficacy of SPC embolization, demonstrating a significant decrease in SPC flow and Q_P:Q_S and increase in Q_SVC and Q _S. Further studies are needed to assess the durability of the procedure and the effect on Fontan and longer-term outcomes.