New criterion to estimate the ventricular relaxation time constant (/spl tau/)

Left ventricular relaxation time constant (/spl tau/) has been widely used in analysis of ventricular diastolic function. A new criterion to detect the ending point of isovolumic relaxation period (IRP) for the estimation of /spl tau/ in the left ventricular pressure waveform was developed. The proposed method is based on the pattern classification of mean square error between the original and the reconstructed pressure waveforms. We verified the performance of the new method using over 20,000 beats obtained from 96 patients. It showed that the proposed method provides more stable and accurate estimation results. The developed method is now being used in clinical application of real-time analysis of left ventricular diastolic function during cardiac catheterization procedure.