Background and aim of the study: To date, transapical aortic valve implantation has required a balloon-expandable stented valve prosthesis. More recently, a novel self-expanding sutureless stented bovine pericardial prosthesis has been developed which allows rapid aortic valve replacement via an open transaortic approach in humans. The aim of this animal study was to develop a reliable protocol to facilitate the transapical implantation of this self-expanding valve in a porcine model.
Methods: Off-pump transapical aortic valve implantation was performed through a left mini-thoracotomy using a bovine pericardial valve mounted on a self-expandable nitinol stent of size 21 mm and 23 mm in 11 pigs (average weight 60 kg). The crimped valve was introduced through the left ventricular apex using a flexible and steerable delivery sheath, using a three-step technique. Biplane fluoroscopy and transesophageal echocardiography were simultaneously used for guidance. Successful adjustment of alignment along three axes prior to deployment of the valve was accomplished in each animal. Deployments were performed during a period of rapid pacing.
Results: All valves were successfully deployed and functioned normally following transapical removal of the delivery system. Paravalvular leak was documented in one case (9.1%) due to prosthetic misalignment. There was no evidence of valve migration. Correct anatomic seating was confirmed during post-procedure necropsy.
Conclusion: Successful transapical implantation of a novel self-expandable bovine pericardial valve was accomplished in 11 animals, without cardiopulmonary bypass. A flexible, steerable delivery system with a three-step release mechanism allowed precise positioning of the valve with a low rate of paravalvular leakage, and excellent device stability.