TRANSLUMINAL AORTIC-VALVE PLACEMENT - A FEASIBILITY STUDY WITH A NEWLY DESIGNED COLLAPSIBLE AORTIC-VALVE

Percutaneous stents are used in vascular applications in conjunction w ith angioplasty and in combination with graft material for repair of a bdominal aneurysms. The authors have designed a collapsible bioprosthe tic aortic valve for placement by a transluminal catheter technique. T his trileaflet stent valve is composed of stainless steel and bovine p ericardium. Stent valves, 23 and 29 mm, were tested in a pulse duplica tor system with rigid rings from 21 to 31 mm in 2 mm increments. At a mean flow of 3.1 L/min (+/-0.7), normal systemic aortic pressure was g enerated with a transvalvular gradient of 14.9 +/- 7 mmHg (mean +/- SD ). Regurgitation fraction ranged from 10 to 18% (mean 13.8 +/- 3%) in the best ring size. Valves with the best hemodynamic profile were used for implantation in three 70 kg pigs in an open chest model. The valv e was collapsed in a 24 Fr catheter designed to allow slow, controlled release. After resection of the native leaflets, the new valve was pl aced in the subcoronary position. No additional sutures were used for securing the valve. Two animals were successfully weaned from cardiopu lmonary bypass and maintained systemic pressures of 100/45 (+/-10) and 116/70 (+/-15) mmHg, respectively. Intraoperative color echocardiogra phy revealed minimal regurgitation, central flow, full apposition of a ll leaflets, and no interference with coronary blood flow. Both animal s were sacrificed after being off bypass for 2 hr. Postmortem examinat ion revealed the valves to be securely anchored. The third animal was weaned from cardiopulmonary bypass but developed refractory ventricula r fibrillation because of valve dislodgment due to structural failure. Although long term survival data are needed, development of a hemodyn amically acceptable prosthetic aortic valve for transluminal placement is feasible.