Detection of "pathologic" prosthetic valve stenosis via exercise Doppler echocardiography

To detect borderline mitral valve dysfunction in asymptomatic patients, with Björk-Shiley valves, we studied the patients' hemodynamics at rest and during exercise by Doppler echocardiography. Supine bicycle exercise was performed by 65 patients. The patients were divided into two groups according to the measurements of the exercise Doppler echocardiography: a normally functioning group (n = 45) and a borderline group (n = 20). The valve area at rest was 2.0 ± 0.6, 2.1 ± 0.7, and 2.3 ± 0.5cm² with valve sizes of 25, 27, and 29 mm, respectively, in the normal group and 1.9 ± 0.5, 1.9 ± 0.4, and 2.1 ± 0.3 cm² in the borderline group. The mitral valve area did not significantly change with exercise in either group. In the normal group, peak gradients increased from 9.9 ± 3.5, 9.7 ± 1.1, and 9.5 ± 1.6 mmHg with valve sizes of 25, 27, and 29 mm, respectively, at rest to 15.1 ± 3.1, 14.0 ± 3.3, and 14.8 ± 2.6 mmHg with exercise. Mean gradients increased from 5.2 ± 1.2, 5.9 ± 1.3, and 5.8 ± 1.8 mmHg with valve sizes of 25, 27, and 29 mm, respectively, at rest to 8.0 ± 2.5, 9.1 ± 2.0, and 8.8 ± 1.6 mmHg with exercise. In the borderline group, peak gradients increased from 10.5 ± 3.1, 10.1 ± 2.1, and 10.8 ± 1.7 mmHg with valve sizes of 25, 27, and 29 mm, respectively, at rest to 24.5 ± 4.2, 23.6 ± 4.4, and 22.4 ± 3.2 mmHg with exercise. The mean gradients increased from 5.8 ± 1.8, 6.0 ± 1.9, and 6.1 ± 1.6 mmHg, at rest to 13.4 ± 2.8, 13.4 ± 2.3, and 12.5 ± 2.2 mmHg after exercise. The increase in both peak and mean gradients with exercise (exercise - resting gradient) in the borderline group (more than 10 mmHg and more than 5 mmHg, respectively) was significantly higher than that in the normal group. Four of the 65 patients underwent reoperation for valve dysfunction due to pannus formation. All 4 of these patients were in the borderline group. Hemodynamic characteristics in the borderline stenotic patients were revealed by exercise. Exercise Doppler echocardiographic measurements can predict a concealed "pathologic" prosthetic valve stenosis in asymptomatic patients.