Transapical approach for aortic stented valve implantation: experimental results

OBJECTIVE: Percutaneous aortic valve replacement has been performed in humans mainly for non-surgical candidates. We evaluated on animals a transapical approach to deliver an aortic stented valve without cardiopulmonary bypass. METHODS: A tubular pericardial valve fixed within a cobalt-nickel stent (Medtronic, Inc.) was implanted using a transapical approach in five adult sheep. A left thoracotomy was used to access the apex of the heart. The crimped valve was deployed in orthotopic position with a valvuloplasty balloon catheter on the beating heart after decreasing the left ventricular pressure by using either drugs or inferior vena cava occlusion. Deployments were performed under fluoroscopy and epicardial 2D Doppler echocardiography. Exact positioning of the valve into the target area was confirmed by autopsy at the end of the procedures. RESULTS: Valves were unsuccessfully deployed at the target site in all cases but one. Three valves were implanted in a supra-annular position with two of them in supracoronary position. One valve was implanted below the native annulus in the outflow tract. Valvular leak was noted in all but one implants. Coronary obstruction occurred twice and early valve retrograde migration once. Ventricular fibrillation or diastolic cardiac arrest occurred less than 20 minutes after stent deployment in all cases. CONCLUSION: In our experience the transapical approach does not facilitate delivery of a stented valve. Despite its technically feasibility, advanced stent design and improvements in delivery system are required before to continue experimental studies in transapical approach for aortic stented valve.