Total cavopulmonary connection in patients with apicocaval juxtaposition: optimal conduit route using preoperative angiogram and flow simulation†

Abstract

Single ventricle with apicocaval juxtaposition (ACJ) is a rare, complex anomaly, in which the optimal position of the conduit for completion of total cavopulmonary connection (TCPC) is still controversial. The purpose of this study was to identify a preoperative method for optimal conduit position using the IVC anatomy and computational fluid dynamics (CFD). Twenty-four patients with ACJ (5.3 ± 5.7 years) who underwent TCPC were enrolled. A conduit was placed ipsilateral to the cardiac apex in each of 11 patients, of which 9 were intra-atrial and 2 extracardiac (group A) and, in a further 13 patients, extracardiac on the contralateral side (group B). As control, 10 patients with tricuspid atresia were also enrolled (group C). The location of the IVC in relation to the spine was evaluated from the frontal view of preoperative angiogram, using the following index: IVC-index = IVC width overlapping the vertebra/width of the vertebra × 100%. Energy loss was calculated by CFD simulation. IVC-index of group B was larger than groups A and C (45 ± 26 vs. 20 ± 21 and 28 ± 19%, P = 0.03). Postoperative catheterizations showed that, due to its curvature, conduit length in group B was significantly longer than the others (65 ± 12 vs. 36 ± 14 and 44 ± 10 mm, P < 0.001), although there was no statistical difference in central venous pressure or cardiac output. CFD studies revealed less energy loss in group A conduits compared with group B (1.6 ± 0.3 vs. 3.6 ± 0.6 mW, P = 0.05), although this did not appear to be clinically significant. Moreover, CFD simulation showed significant energy loss within the Fontan circulation when the conduit was either compressed or kinked: 4.9 and 18.2 mW respectively. In patients with ACJ, placement of a straighter and shorter conduit on the ventricular apical side provides better laminar blood flow with less energy loss. However, conduit compression and kinking are far more detrimental to the Fontan circulation. A preoperative IVC-index is pivotal for avoiding these factors and deciding the optimal conduit route.