Variability of estimation of diastolic function parameters from pressure-volume loops using acoustic quantification from echocardiography

Acoustic quantification (AQ) can be used to acquire instantaneous left ventricular volume curves, but the slow sampling rate and dependence on gain and region of interest cause variability in desired parameters. The authors´ aim was to study the variability and the correlation between parameters measuring diastolic myocardial function. In an open chested dog model, pressure-volume (P-V) loops were generated using AQ and micromanometer catheters. Parameters of diastolic function were investigated by repeated measurements on single cardiac cycles and by ensemble averaging (EA) of multiple cardiac cycles. It was found that dV/dt derived from AQ and /spl tau/ derived from pressure both varied in directions appropriate to changes in inotropic state. However, the variability in pressure based parameters (/spl tau/ and negative dp/dt) was less than volume (dV/dt and time to peak filling rate) or pressure-volume (volume constant and slope of diastolic P-V relationship) based diastolic function parameters (pressure based: 2.23/spl plusmn/0.50%, volume based: 18.09/spl plusmn/2.54%, P-V based: 42.30/spl plusmn/10.09%). Correlations between pressure based parameters (r=0.84) were better than those involving volume based parameters (r=0.02 to 0.40). It is concluded that generation of volume based measures of diastolic function is feasible, however, excessive variability inherent in AQ measurement of volume makes volume or P-V derived parameters of diastolic function unreliable with current technology.<>