Background. Left ventricular (LV) relaxation time constant (Tau) is a relatively load-independent index of diastolic function in the evaluation of heart failure. However, the requirement of high-fidelity intraventricular pressure recording limits its clinical utility. In the present study, we investigated whether Tau could be estimated noninvasively. Methods. Thirty-seven patients indicated for cardiac catheterization were recruited for study. Echocardiography and cardiac catheterization with high-fidelity LV pressue recording were performed sequentially within 1 hour. The non-invasive Taud,Dopp was derived from the formula: TauDopp = IVRTDopp/ [ln(Ps) - ln(10)], where IVRT is the isovolumic relaxation time measured by Doppler echocardiography and Ps is systolic blood pressure measured during the echocardiographic examination. The invasive TauLM was determined by non-linear least-square parameter estimate technique, using the exponential equation: Pv = P0e-t/Tau + b, where Pv is the instantaneous LV pressure, P0 is LV pressure at minimal dP/dt, and b is the theoretical asymptote. The difference between TauDopp and TauLM was compared using paired t-test, and their relation was evaluated using simple correlation and intra-class correlation coefficient. Results. IVRTDopp was significantly correlated with the invasively derived IVRT (r = 0.42, p = 0.012). The completely non-invasive TauDopp was significantly correlated with the direct curve-fitted TauLM (r = 0.41; p = 0.013), and the intraclass correlation coefficient was 0.29 (p 0.04). In addition, TauDopp was significantly smaller than TaULM (36 ± 6 ms vs. 57 ± 15 ms,p < 0.001). Conclusions. Tau can be estimated noninvasively by transthoracic Doppler echocardiographic method with limited accuracy. The clinical utility of TauDopp remains to be determined.
|頁（從 - 到）||317-322|
|期刊||Journal of the Chinese Medical Association|
|出版狀態||已發佈 - 七月 1 2004|
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