Doppler echocardiography evaluation of the CarboMedics valve in patients with small aortic anulus and valve prosthesis-body surface area mismatch

A Doppler echocardiographic study was performed to evaluate the hemodynamic performances of small diameter CarboMedics aortic valves (CarboMedics, Inc., Austin, Tex.) in patients with a mismatch between the prosthetic valve and body surface area. Fourteen patients receiving either a 19 mm (n = 7) or a 21 mm valve (n = 7) prosthesis were studied. Only patients with a body surface area greater than 1.65 m2 were included in the study. Pulsed and continuous wave Doppler echocardiography was performed at rest and 2 minutes after treadmill exercise with the Bruce protocol. Peak and mean gradients across the valve prosthesis were estimated; effective orifice area, performance index, and discharge coefficient of the valve prosthesis were calculated. All patients achieved a significant increase in heart rate, systolic blood pressure, and cardiac output with exercise. Mean gradients +/- standard deviation of the mean at rest and 2 minutes after exercise were 20.1 +/- 7.1 mm Hg and 21.8 +/- 9 mm Hg for the 19 mm prosthesis and 12.3 +/- 3.4 mm Hg and 15.9 +/- 3.9 mm Hg for the 21 mm prosthesis. The 19 mm valve prosthesis significantly increased the effective orifice area with exercise (1.02 +/- 0.2 versus 1.20 +/- 0.3; p < 0.05), whereas it was almost unmodified for the 21 mm valve (1.38 +/- 0.2 versus 1.39 +/- 0.3; p = not significant). Therefore, despite a similar increase in cardiac output with exercise, only the 21 mm valve prosthesis showed a significant increase in peak (25.4 +/- 5.2 versus 34.9 +/- 8.1 mm Hg) and mean gradient (p < 0.01). We conclude that small diameter CarboMedics valves have satisfactory hemodynamic performances even after strenuous exercise in patients with large body surface areas. The hemodynamic performances of the 19 mm valve prosthesis seem to be optimized with exercise.