Relative duration of transmitted mitral A wave as a measure of left ventricular end-diastolic pressure and stiffness

The mitral A wave is transmitted to the left ventricular (LV) outflow tract where it is registered as Ar wave. We have related its transit time to the LV late diastolic stiffness. We also observed incidentally that the duration of the transmitted Ar wave exhibited marked variability and hence investigated its hemodynamic correlates.

Mitral A wave and the Ar wave in the LV outflow tract were recorded using pulsed wave Doppler technique simultaneous with high fidelity LV pressure recordings in 20 patients undergoing cardiac catheterization. A high-speed contrast left ventriculogram was obtained as well. The duration of both these wave forms were measured and A wave duration minus the Ar wave duration was measured. The A minus Ar wave duration (range 0-95 ms) correlated with LV end-diastolic pressure (r = 0.54, P = 0.014, range 4-32 mmHg), LV late diastolic stiffness (r = 0.62, P = 0.004, range 0.1-1.6 mmHg/ml) and the amount of LV pressure rise with atrial contraction (r = 0.67, P = 0.001, range 2-13 mmHg).

A minus Ar wave duration is an easily obtainable Doppler parameter that is related to LV late diastolic filling pressures and stiffness and gives insights into aspects of LV diastolic function.