...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Canadian Journal of Physiology and Pharmacology >Half-logistic time constant: a more reliable lusitropic index than monoexponential time constant regardless of temperature in canine left ventricle.
【24h】

Half-logistic time constant: a more reliable lusitropic index than monoexponential time constant regardless of temperature in canine left ventricle.

机译：半逻辑时间常数：比单指数时间常数更可靠的Lusitropic指数，无论犬左心室的温度如何。

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Temperature changes influence cardiac diastolic function. The monoexponential time constant (tauE), which is a conventional lusitropic index of the rate of left ventricular (LV) pressure fall, increases with cooling and decreases with warming. We have proposed that a half-logistic time constant (tauL) is a better lusitropic index than tauE at normothermia. In the present study, we investigated whether tauL can remain a superior measure as temperature varies. The isovolumic relaxation LV pressure curves from the minimum of the first time derivative of LV pressure (dP/dtmin) to the LV end-diastolic pressure were analyzed at 30, 33, 36, 38, and 40 degrees C in excised, cross-circulated canine hearts. tauL and tauE were evaluated by curve-fitting using the least squares method and applying the half-logistic equation, P(t) = PA/[1 + exp(t/tauL)] + PB, and the monoexponential equation, P(t) = P0exp(-t/tauE) + Pinfinity. Both tauL and tauE increased significantly with decreasing temperature and decreased withincreasing temperature. The half-logistic correlation coefficient (r) values were significantly higher than the monoexponential r values at the 5 above-mentioned temperatures. This implies that the superiority of the goodness of the half-logistic fit is not temperature dependent. The half-logistic model characterizes the amplitude and time course of LV pressure fall more reliably than the monoexponential model. Hence, we concluded that tauL is a more useful lusitropic index regardless of temperature.
机译：温度变化会影响心脏舒张功能。单指数时间常数（tauE）是左心室（LV）压力下降率的常规垂直指数，随冷却而增加，随加热而减少。我们已经提出，在常温下，半逻辑时间常数（tauL）比tauE是更好的垂直指数。在本研究中，我们调查了tauL是否可以在温度变化时保持较好的测量效果。在切除，交叉循环的30、33、36、38和40摄氏度下分析了从LV压力一阶导数的最小值（dP / dtmin）到LV舒张末期压力的等容松弛LV压力曲线犬的心。使用最小二乘法通过曲线拟合并应用半逻辑方程P（t）= PA / [1 + exp（t / tauL）] + PB和单指数方程P（t ）= P0exp（-t / tauE）+ Pinfinity。 tauL和tauE均随温度降低而显着增加，而随温度升高而降低。在上述5个温度下，半逻辑相关系数（r）值明显高于单指数r值。这意味着半逻辑拟合优度的优劣与温度无关。半逻辑模型比单指数模型更可靠地表征低压降的幅度和时间过程。因此，我们得出结论，无论温度如何，tauL都是更有用的垂直指数。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号