Effect of heart rate on pressure half-time in patients with mitral stenosis.

The effect of heart rate on pressure-half time has been controversial. This study attempted to clarify this issue in patients with mitral stenosis. Twenty cases were enrolled, 10 with atrial fibrillation and 10 with sinus rhythm. Twenty beats were analyzed for each patient. The results showed that in patients with atrial fibrillation the pressure half-time was hardly measurable in the cardiac cycles with a ventricular rate more than 100/min; by excluding these fast beats, the pressure half-time showed no relationship with the heart rate. Similarly, there was no significant correlation between heart rate and pressure half-time in patients with sinus rhythm when the heart rate was less than 70/min. However, if the sinus rate was more than 70/min, the correlation became statistically significant. We conclude that when using pressure half-time to derive mitral valve area we should avoid to use the beats with ventricular rate greater than 100/min in patients with atrial fibrillation. In patients with sinus rhythm, we should try to use those beats with heart rate greater than 70/min if possible. Otherwise, significant error may occur.