Erwan M. Flecher

Sutureless Stented Aortic Valve Implantation Under Direct Vision: Lessons From a Negative Experience in Sheep

Abstract  Background and Aim of the Study: Percutaneous aortic valve replacement has been proposed as a valid alternative to surgery in selected cases; however, it still has many problems. As a less radical preliminary step, we implanted a balloon‐expandable stented aortic valve under direct vision in sheep. Methods: Under cardiopulmonary bypass (CPB) and through a transverse aortotomy, an aortic valve mounted in a long tubular balloon‐expandable stent was implanted in six acute sheep. The leaflets were not excised and no anchoring sutures were used between stent and native annulus. Epicardial, two‐dimensional color Doppler echocardiography was used to assess the function of the stented valve followed by macroscopic inspection at necropsy. Results: Direct visualization of the entire annulus when the collapsed, valved stent was placed within the aortic root was difficult in all animals. Valve deployment took less than 1 minute. The surgical procedure resulted in major complications in all cases. Migration (3/6), paravalvular leak (2/6), mitral conflicts resulting in mitral regurgitation (1/6), and coronary ostia obstruction (2/6) were the major events at the origin of the failure. Only three animals could be weaned from CPB but did not recover enough to survive the procedure. Conclusions: Sutureless implantation of a stented aortic valve through standard CPB and aortotomy is far more complex than expected. Changes in stent design and surgical approach are indicated.

In vitro study of percutaneous aortic valve replacement: selection of a tissue valve.

Abstract  Background: Selection of the best tissue valve is an essential step before percutaneous aortic valve replacement (PAVR) becomes a clinical reality. The aim of this study was to evaluate in vitro three different tissue valves mounted within the same endovascular stent. Methods: Thirty stented valves (10 aortic porcine, 10 pulmonary porcine, and 10 pericardial tubular) were sutured within a 32‐mm long by 23‐mm diameter cobalt‐nickel stent. The porcine valves were trimmed down close to the cusps. All valves were delivered with a percutaneous valvuloplasty catheter and placed orthotopically in a latex root that was cast from a sheeps aorta. The roots were tested in a pulse duplicator at a rate of 60 beats per minute and 3.5 liters per minute. The transvalvular gradient, maximum valve orifice area, and presence of central and paravalvular leaks were recorded echocardiographically. Results: Within the limitations of implantation in a synthetic, noncalcified annulus, the pericardial valve performed best in terms of orifice area, transvalvular gradients, and tissue bulk; but four of the ten valves showed a central leak due to the type of stent used. Conclusion: The ideal valve for PAVR should collapse with minimal bulk to avoid coronary obstruction and central and paravalvular leaks. The tubular pericardial valve showed the lowest pressure gradients and was the most compressible, but was more open to manufacturing errors.