Midterm evaluation of hemodynamics of the Top Hat supraannular aortic valve.

The CarboMedics Top Hat supraannular aortic valve provides an orifice-to-annulus ratio of 1:1 in most patients, and enhances patient outcomes. This study compared the midterm echocardiographic parameters of 52 patients undergoing aortic valve replacement with a Top Hat valve with those in other studies of Top Hat or CarboMedics intraannular valves. Echocardiography was performed 6-48 months after surgery with Top Hat sizes 21-27. Parameters evaluated included mean gradient, peak gradient, effective orifice area, and effective orifice area index. Preoperative and postoperative echocardiographic measurements were compared in 38 patients with aortic valve stenosis. Hemodynamic data were comparable to those of other studies, but the Top Hat prosthesis implanted was significantly larger (by a mean of 3.29 mm) than the valve size indicated using an intraannular valve sizer in 48 patients. Mean effective orifice area improved significantly from 0.73 cm(2) preoperatively to 2.04 cm(2) postoperatively. In patients with preoperative aortic valve stenosis, postoperative mean peak gradient was significantly reduced. The larger orifice-to-annulus ratio of the Top Hat valve improved hemodynamic parameters assessed by echocardiography up to 4 years postoperatively, with a lower transvalvular gradient, hence decreased left ventricular workload.