Hemodynamic performances of small diameter carbomedics and St. Jude valves

Optimal hemodynamic performances are of paramount importance when implanting a mechanical valve in patients with a small aortic annulus. A Doppler echocardiographic study was performed to compare the hemodynamic performances of small CarboMedics and St. Jude valves.

Twenty-nine patients receiving either a 19 mm (n = 10) or a 21 mm (n = 10) CarboMedics valve or a 19 mm (n = 9) St. Jude Med HP valve were evaluated. A Doppler echocardiographic study was performed at rest and two minutes after treadmill exercise with the Bruce protocol. Peak and mean gradients across the valve were estimated; effective orifice area, performance index and discharge coefficient were calculated. Heart rate, blood pressure and cardiac output were all significantly increased with exercise.

Peak and mean gradients at rest were significantly higher (p < 0.05) in the 19 mm CarboMedics valve (40.2 +/- 15 mmHg and 22.6 +/- 9 mmHg, respectively) when compared either with 21 mm CarboMedics valve (27.6 +/- 6.8 mmHg and 14.2 +/- 3.4 mmHg, respectively) or with the 19 mm St. Jude HP valve (23.6 +/- 10.4 mmHg and 13.6 +/- 5 mmHg, respectively). Peak and mean gradients were not modified with exercise for the 19 mm CarboMedics valve and significantly increased for the 21 mm CarboMedics and the 19 mm St. Jude HP valves. Although these values were still higher in the 19 mm CarboMedics valve, they did not reach the level of statistical significance when compared with the other two valve groups.

The 19 mm St. Jude HP valve shows hemodynamic performances at rest that are similar to those of the 21 mm CarboMedics valve and superior to those of the 19 mm CarboMedics valve. With exercise both sizes of the CarboMedics valve show an in vivo discharge coefficient close to one, testifying to a full utilization of the internal orifice area.