Functional hemodynamic assessment of the 21-mm and 23-mm CarboMedics Top Hat aortic prosthetic valve

Between 1993 and 1996 the CarboMedics Top Hat supraannular aortic valve was implanted in 41 patients at the Wessex Cardiothoracic Centre (age, 39 to 7 4 years; mean, 61.3 +/- 8.9 years). Comparisons of annular dimensions made at surgery indicate that conventional annular valve replacement would have required at least a size smaller valve. This was particularly marked when a prosthetic mitral valve was in place. Operative mortality was 2.4%. There were also three late deaths. Echocardiography before and after symptom-limi ted treadmill testing has been performed in 21 patients. The mean time to f ollow-up was 16.1 months. The Doppler-derived indices of forward flow pre- and postexercise were expressed as mean +/- standard deviation. For 23-mm v alves the values were: peak valve gradient 21.43 +/- 7.46 mmHg and 35.86 +/ - 14.4 mmHg, aortic valve area 1.13 +/- 0.39 cm(2) and 1.24 +/- 0.54 cm(2). For 21-mm valves the values were: peak valve gradient 24.84 +/- 8.2 mmHg a nd 31.29 +/- 5.84 mmHg, aortic valve area 1.08 +/- 0.44 cm(2) and 0.95 +/- 0.2 cm(2). The Top Hat valve has a good hemodynamic profile at rest and dur ing exercise. Surgical considerations make it particularly useful in patien ts with a small aortic annulus and in patients undergoing combined aortic a nd mitral valve replacement.