Inaccuracy of doppler pressure half-time in estimation of mitral value area during hemodynamic exercise in patients with mitral stenosis

ABSTRACT

Patients with mitral stenosis often present during periods of hemodynamic change like pregnancy, tachycardia or infection. Doppler pressure half-time [PHT] method is a well accepted noninvasive tool for estimation of mitral valve area [MVA] in patients with mitral stenosis [MS]. However, recent reports have questioned its validity during periods of exercise. 24 patients [mean age 26 +/- 8 years] were studied with isolated MS by Doppler echocardiography at rest and during supine bicycle exercise. The mean resting heart rate significantly increased from 70 +/- 8 beats/min. [mean +/- SD] to 96 +/- 8 beats/min. [p <0.001]. MVA was estimated by both PHT and continuity equation methods at rest and during exercise. Results were compared with those obtained by Gorlin's formula at cardiac catheterization done within 48 hours. Both mean and peak transmitral pressure gradients were significantly increased during exercise [p <0.001]. Also, estimation of the net atrioventricular compliance decreased significantly during exercise [p <0.001]. At rest, there was good agreement between MVA by PHT [1.04 +/- 0.44 cm2], continuity equation [0.87 +/- 0.33] and catheterization [0.9 +/- 0.33] [p = NS]. During exercise, MVA by continuity equation showed nonsignificant changes from resting valve [0.86 +/- 0.34] [p = NS], while significant increase of MVA during exercise occurred when PHT method was used [1.5 +/- 0.5 cm2] [p <0.001]. In conclusion, caution should be taken in evaluating severity of MS by PHT during periods of hemodynamic stress