Off-bypass implantation of a self-expandable valved stent between inferior vena cava and right atrium.

A glutaraldehyde preserved valved bovine jugular xenograft mounted in a nitinol 'Z' stent, expandable from 7 to 28 mm of internal diameter, was evaluated in vitro (column of water developing a pressure of 45 mmHg and a mock loop including a pulsatile pump) and in vivo in five adult pigs with intra-vascular ultrasound to measure the inferior vena cava diameter via a retroperitoneal access. Through a stent-graft delivery system (24 French) the self expandable valved stent was implanted off-bypass in the inferior vena cava, between hepatic veins and cavo-atrial junction, with flow and pressure gradient recording. The mean length of the valved stent was 22.80+/-1.06 mm, the mean internal diameter 20.97+/-0.5 mm and the mean external diameter 26.67+/-0.9 mm. The valve leaking under pressure was 32.5+/-12.3 ml/min. The mean pressure gradient recorded across the self expandable valved stent implanted in the inferior vena cava was 1.0+/-0.5 mmHg (range 0-2 mmHg). Intra-vascular ultrasound showed partial opening and closing of the valve (mean area reduction from 148.5 to 81.5 mm2), with almost complete occlusion only during deep breaths. The in vitro and in vivo experiments confirmed the feasibility of potential application of the self-expandable valved stent implanted off-bypass in the inferior vena cava for late conversion of failing total cavo-pulmonary connection; intra-vascular ultrasound allows for adequate implantation and evaluation.