Does caval aplanarity influence power losses across in vitro cavopulmonary connections?

Optimally designed cavopulmonary connections are desirable to reduce transanastomotic power loss. Since aplanarity of the total cavopulmonary connections results from the natural anterior-posterior position of the superior vena cava and the right pulmonary artery, the aim of this study was to investigate the influence of aplanarity of caval offset on transanastomotic power losses. Two types of cavopulmonary connections, a planar cross-like connection and a nonplanar V-shaped anastomosis, were studied in a mock circulation, comparing for each type native porcine vessels and Perspex glass models. Total flow varied between 1200 and 6000 ml/min at superior to inferior caval flow ratios of SVC/IVC = 50/50% and 33/67%, respectively. Pressures and flows were measured and power losses calculated. No significant differences in power losses were found between the planar and aplanar connections for native vessels or for Perspex glass models. Power losses across the native preparations in each configuration were significantly higher than those in the corresponding Perspex glass model. The simulation of the natural aplanar V-shaped caval offset in total cavopulmonary connections used to bypass the right ventricle seems to have no relevant additional effect on in vitro power losses compared to planar connections.