MECHANICAL RESTITUTION OF ISOLATED PERFUSED CANINE LEFT-VENTRICLES
MECHANICAL RESTITUTION OF ISOLATED PERFUSED CANINE LEFT-VENTRICLES
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DOI：
10.1152/ajpheart.1984.246.1.h8
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发表时间：
1984-01-01
影响因子：
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通讯作者：
SAGAWA, K
中科院分区：
文献类型：
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作者：
BURKHOFF, D;YUE, DT;SAGAWA, K
测量心脏机械恢复曲线，该曲线描述了稳态搏动后心室收缩强度恢复的时间过程。在第一系列实验中，使用dP/dtmax [压力随时间的最大变化]作为独立于心室前负荷和后负荷变化影响的收缩强度的可靠指标，研究了等容搏动的左心室。机械恢复的开始被认为是与发病的电痉挛;此后，收缩强度呈单指数上升到一个平台，保持测试脉冲间隔长达15秒。恢复时间常数（通常为245 ms）与预充频率和心室容积无关。这些发现被解释在心肌细胞内的细胞内钙流的模型。在第二系列实验中，检查了来自对模拟动脉阻抗系统喷射的孤立心室的机械恢复曲线。在此条件下，没有观察到在等容条件下测量的机械恢复的单指数时间过程。在等容和射血条件下测得的机械恢复曲线之间的差异可能归因于改变血流动力学条件对dP/dtmax的影响，使其成为不可靠的收缩强度指标。
Cardiac mechanical restitution curves which describe the time course of recovery of ventricular contractile strength following a steady-state beat were measured. In the 1st series of experiments, left ventricles that beat isovolumically were studied using dP/dtmax [maximum change in pressure over time] as a reliable index of contractile strength independent of the influence of changing ventricular pre- and afterload. The commencement of mechanical restitution was found to be associated with the onset of electrical diastole; thereafter, contractile strength rose monoexponentially to a plateau that was maintained for test pulse intervals as long as 15 s. The time constant of restitution (typically 245 ms) was independent of priming frequency and ventricular volume. These findings were interpreted in terms of a model of intracellular Ca fluxes within the myocardial cells. In a 2nd series of experiments, mechanical restitution curves from isolated ventricles that ejected against a simulated arterial impedance system were examined. Under this condition, the monoexponential time course of mechanical restitution as was measured under isovolumic conditions was not observed. The differences between the mechanical restitution curves measured under isovolumic and ejecting conditons may be attributed to the influences of changing hemodynamic conditions on dP/dtmax, causing it to be an unreliable index of contractile strength.