Role of exercise Doppler echocardiography in isolated mitral stenosis

This study reports the role of Doppler ultrasound during exercise for assessment of patients with mitral stenosis. Doppler echocardiography was performed at rest and during symptom-limited supine bicycle exercise in ten patients with isolated mitral stenosis. The mean mitral valvular gradient was calculated using modified Bernoulli's equation, and the mitral valvular area was estimated from the equation, 220/pressure half-time. During exercise the heart rate increased from 74 +/- 14 beats per minute (mean +/- SD) at rest to 110 +/- 8 beats per minute (p less than 0.001) during exercise. The mean mitral gradient increased from 9 +/- 5 mm Hg at rest to 18 +/- 7 mm Hg (p less than 0.01) during exercise. The mitral pressure half-time decreased from 225 +/- 62 msec at rest to 190 +/- 42 msec during peak exercise (p less than 0.005). This corresponded to a reduction of 15 percent. The estimated mitral valvular area increased from 1.0 +/- 0.4 sq cm at rest to 1.2 +/- 0.3 sq cm at peak exercise (p less than 0.005). In conclusion, Doppler echocardiography can be used to evaluate patients with mitral stenosis, with the response of the mitral valvular gradient being the index of obstruction; however, caution should be used in applying the mitral pressure half-time for estimation of the mitral valvular area at high heart rates and flows.