Bidirectional superior cavopulmonary anastomosis improves mechanical efficiency in dilated atriopulmonary connections

Abstract

Objective: Few therapeutic options exist for patients with failing dilated atriopulmonary connections. We addressed the hypothesis that a bidirectional superior cavopulmonary anastomosis will improve the hemodynamic efficiency of dilated atriopulmonary connections while maintaining physiologic pulmonary flow distributions. Methods: Dilated atriopulmonary connections with and without a bidirectional superior cavopulmonary anastomosis were created in explanted sheep heart preparations and transparent glass models. A mechanical energy balance and flow visualization were performed for 6 flow rates (1-6 L/min), both with and without the bidirectional superior cavopulmonary anastomosis, and were then compared. A novel contrast echocardiographic technique was used to quantify inferior vena cava flow (hepatic venous return) distributions into the pulmonary arteries. Results: The rate of fluid-energy dissipation was 52% ± 14% greater in the dilated atriopulmonary anastomosis than in the bidirectional superior cavopulmonary anastomosis model over the range of flow rates studied ( P = 6.3E –3). Total venous return passing to the right pulmonary artery increased from 41% ± 2% to 47% ± 3% ( P = 9.7E –3) and that for inferior vena cava flow decreased from and 42% ± 3% to 12% ± 4% ( P = 3.3E –4) after addition of the bidirectional superior cavopulmonary anastomosis. Flow visualization confirmed more ordered atrial flow in the bidirectional cavopulmonary anastomosis model, resulting from a reduction of caval flow stream collision and interaction. Conclusions: A bidirectional cavopulmonary anastomosis reduces fluid-energy dissipation in atriopulmonary connections, provides a physiologic distribution of total flow, and maintains some hepatic venous flow to each lung. This approach may be a technically simple alternative to atriopulmonary takedown procedures and conversions to total cavopulmonary connections in selected patients. (J Thorac Cardiovasc Surg 1999;118:681-91)