Berger D S, Li J K
Department of Biomedical Engineering, Rutgers University, Piscataway, NJ 08855.
IEEE Trans Biomed Eng. 1992 Apr;39(4):404-10. doi: 10.1109/10.126613.
Arterial compliance is an important component of ventricular afterload. Although its pressure dependence has been recognized, its temporal relationship to ventricular elastance (Elv(t)) has not been established. We investigated this in five open chest anesthetized dogs where simultaneous aortic pressure and flow and left ventricular pressure were measured. Elv(t) was derived using an elastance-resistance model of the left ventricle assuming an ejection fraction of 0.50 and a dead volume (Vd) of 3.0 mL. The nonlinear pressure-dependent compliance (C(P)) of the arterial system was incorporated in a three-element Windkessel model and determined by accurate prediction of aortic pressure from aortic flow. The resulting arterial elastance (Eas(t)) was computed as Eas(t) = 1/C(P). Results show that Eas(t) reaches a minimum value at or near the start of ventricular ejection and attains its peak value at or near the same time maximum LV elastance (Emax) is reached, at end-systole. Finally, numerical simulation of the model demonstrates its ability to adequately reproduce measured pressure and flow. Thus, the arterial system, in terms of elastance, is dynamically and temporally coupled to the left-ventricle during ejection.
动脉顺应性是心室后负荷的一个重要组成部分。尽管其压力依赖性已得到认可，但其与心室弹性（Elv(t)）的时间关系尚未确定。我们在五只开胸麻醉犬身上对此进行了研究，同时测量了主动脉压力、流量和左心室压力。Elv(t)是通过假设射血分数为0.50和死腔容积（Vd）为3.0 mL的左心室弹性-阻力模型推导得出的。动脉系统的非线性压力依赖性顺应性（C(P)）被纳入一个三元风箱模型，并通过根据主动脉流量准确预测主动脉压力来确定。由此得出的动脉弹性（Eas(t)）计算为Eas(t) = 1/C(P)。结果表明，Eas(t)在心室射血开始时或接近开始时达到最小值，并在收缩期末达到最大左心室弹性（Emax）时或接近此时达到峰值。最后，该模型的数值模拟证明了其能够充分再现测量的压力和流量。因此，就弹性而言，动脉系统在射血过程中与左心室在动态和时间上相互耦合。
