Mizuno Ju, Hanaoka Kazuo, Suga Hiroyuki
Department of Anesthesiology, Faculty of Medicine, The University of Tokyo, Tokyo 113-8655.
Masui. 2006 Aug;55(8):956-62.
A logistic function has been found to fit the isovolumic left ventricular (LV) relaxation pressure curve and the isometric relaxation force curve of the papillary muscle much more precisely than the conventional monoexponential function. Therefore, the logistic time constant (tauL) has been proposed as a better index of the rate of cardiac relaxation or lusitropism than the conventional monoexponential time constant (tauE). Many investigators have reported that tauE changes with preloading. We analysed and compared the effect of LV volume (LVV) loading on both logistic and monoexponential fittings and their time constants of the isovolumic LV relaxation pressure curve in the excised, cross-circulated canine hearts. We found that the logistic fitting was superior to the monoexponential fitting at any LVV. LVV loading did not affect tauL at all but affected tauE slightly. The logistic fitting more reliably characterises the lusitropism than the monoexponential fitting, and tauL, serving as a more reliable ventricular lusitropism index, is independent of changes in LVV loading or the Frank-Starling effect.
已发现逻辑函数比传统的单指数函数能更精确地拟合左心室等容舒张压力曲线和乳头肌的等长舒张力曲线。因此，有人提出逻辑时间常数（tauL）作为心脏舒张速率或舒张性的指标比传统的单指数时间常数（tauE）更好。许多研究者报告tauE会随前负荷而变化。我们分析并比较了左心室容积（LVV）负荷对离体交叉循环犬心等容左心室舒张压力曲线的逻辑拟合和单指数拟合及其时间常数的影响。我们发现，在任何LVV下，逻辑拟合都优于单指数拟合。LVV负荷对tauL完全没有影响，但对tauE有轻微影响。与单指数拟合相比，逻辑拟合能更可靠地表征舒张性，而tauL作为更可靠的心室舒张性指标，独立于LVV负荷变化或Frank-Starling效应。
