Mini-thoracotomy transcatheter pulmonary valve implantation: an experimental study

Objective: To evaluate the feasibility and effectiveness of transcatheter implantation of a new-type domestic self-expandable valve stent to replace the pulmonary valve in experimental goats. Methods: The authors have designed a new cup-like self-expandable nitinol valve stent. Fresh porcine pericardium was treated with cell extracting and anti-calcification, then the treated porcine pericardium was trimmed into artificial leaflets and sutured into the nitinol alloy stent by hand. Eight goats were included in this study. A right anterolateral mini-thoracotomy was performed at the 4th intercostal space. After opening the pericardium, the right ventricle was punctured through anterior wall, and a stiff guidewire was then placed across the outflow tract of right ventricle and anchored in the left or right pulmonary artery. The delivery catheter (18 F) was then introduced through the stiff guidewire into the pulmonary artery under fluoroscopic guidance. After correct valve position was confirmed by digital subtration angiography (DSA), the catheter was slowly withdrawn and the valve stent was released. The immediate outcome of the function of the valve stent was evaluated with angiography and echocardiography after implantation was completed. Results: Eight devices were successfully implanted into pulmonary valve position in experimental goats. Immediate observation with angiography and echocardiogram after the procedure showed that the valve stent was in the desired position in all eight goats. No moderate or severe aortic regurgitation was observed. Angiography and echocardiography confirmed that the valve stent remained in correct position with good functioning in all the eight animals 6 months after the procedure. Conclusion: It is feasible and effective to replace the pulmonary valve with a new-type domestic self-expandable valve stent through right mini-thoracotomy in experimental goats under non-extracorporeal circulation. (authors)