Judd R M, Mates R E
Department of Mechanical and Aerospace Engineering, State University of New York, Buffalo 14260.
Am J Physiol. 1991 Jun;260(6 Pt 2):H1841-51. doi: 10.1152/ajpheart.1991.260.6.H1841.
Although it is well known that coronary inflow decreases substantially during systole, the mechanism responsible for this decrease remains controversial. Knowledge of how coronary input impedance is affected by contraction can differentiate between some of the proposed mechanisms. In open-chest dogs, we have measured coronary inflow in the beating heart both during constant-pressure perfusion and during 10-Hz sinusoidal pressure oscillations around the same constant pressure. By exploiting the principle of superposition, we have shown that coronary input impedance remains unchanged between systole and diastole. Using this result, we have shown that a simple lumped-parameter model with constant resistance and compliance can describe coronary inflow at heart rates of 60, 90, 120, and 150 beats/min both with vasomotor tone intact and during maximal coronary vasodilation. Coronary resistance and compliance determined using the model are comparable to those obtained in our laboratory and by others during normal diastoles and in the arrested heart. The results suggest that, despite large increases in myocardial tissue stresses during systole, coronary resistance and compliance as determined using inflow measurements are constant during systole and diastole.
虽然众所周知，冠状动脉血流量在收缩期会大幅减少，但其减少的机制仍存在争议。了解冠状动脉输入阻抗如何受心肌收缩影响，有助于区分一些提出的机制。在开胸犬中，我们测量了在恒压灌注期间以及在围绕相同恒压的10赫兹正弦压力振荡期间跳动心脏的冠状动脉血流量。通过利用叠加原理，我们表明冠状动脉输入阻抗在收缩期和舒张期之间保持不变。利用这一结果，我们表明，一个具有恒定阻力和顺应性的简单集总参数模型可以描述在血管运动张力完整和冠状动脉最大舒张时心率为60、90、120和150次/分钟时的冠状动脉血流量。使用该模型确定的冠状动脉阻力和顺应性与我们实验室以及其他人在正常舒张期和停跳心脏中获得的结果相当。结果表明，尽管在收缩期心肌组织应力大幅增加，但使用血流量测量确定的冠状动脉阻力和顺应性在收缩期和舒张期是恒定的。
