Mitral E wave propagation to the left ventricular outflow tract. II: Evaluation of left ventricular filling pressures and diastolic stiffness from an analysis of their amplitude and duration in a modeled human left ventricle.

BACKGROUND AND AIMS OF THE STUDY

The rate of mitral E wave propagation inside the left ventricle is related to the rate of left ventricular (LV) relaxation. However, the relationship of the amplitude and duration of the transmitted E wave (EOT wave) to the LV diastolic properties is not known. The hypothesis that the amplitude and duration of the EOT wave is related to the LV filling pressures and its diastolic properties was tested in an in vitro setting of modeled left ventricle.

METHODS AND RESULTS

Thirty-one sets of experiments were conducted in a pulsatile left ventricle model with varying LV filling pressures and operative diastolic characteristics. The EOT wave amplitude correlated with the mean left atrial pressure (r = 0.86, p < 0.0001), LV end-diastolic pressure (r = 0.89, p < 0.0001) and average LV diastolic stiffness (r = 0.38, p = 0.05). The EOT wave duration was not related to any of these measures of LV diastolic function, but E wave duration and EOT/E wave duration ratio were significantly related to LV diastolic stiffness (r = -0.88 and 0.71 respectively, both p < 0.0001). Multivariate equations were developed from the amplitudes and durations of E and EOT waves to predict left atrial and LV end-diastolic pressures and LV diastolic stiffness with a high degree of confidence (cumulative R values 0.92, 0.97 and 0.92 respectively).

CONCLUSIONS

These in vitro findings indicate that LV filling pressures and operative diastolic stiffness may potentially be derived from the amplitudes and durations of diastolic flow waves at the mitral inflow and LV outflow. However, these findings need to be confirmed in in vivo settings.