Doppler-echocardiographic assessment of the carbomedics supra-annular 'Top-Hat' prosthetic heart valve in the aortic position.

Twenty-one CarboMedics 'Top-Hat' bileaflet prostheses were implanted in the aortic position between May 1993 and May 1994 at our institution. Valve performance was assessed by repeat echocardiography. We found it very easy to implant this prosthesis even in the small aortic annulus and it allowed us to implant a valve that is at least one size larger than implantation in the intra-annular position allows. The only contraindication to the implantation of this prosthesis is when the coronary ostia are displaced downwards, which would apply to any supra-annular prosthesis. The Doppler echocardiographic assessment showed acceptable transvalvular gradients and velocity indexes. The Top-Hat prosthesis is now our valve of choice in the small aortic annulus.