Appleyard R F, Campbell K B, Ringo J A
Department of Veterinary, Washington State University, Pullman 99164.
Am J Physiol. 1988 Dec;255(6 Pt 2):H1405-12. doi: 10.1152/ajpheart.1988.255.6.H1405.
We show that power measured by the area of the pressure-flow loop (APQ) is directly proportional to reactive power [Im(W)], which measures pulsatile energy storage in the proximal arteries. Analytically, Im(W) differs from APQ by K.2 pi, where K is a postulated constant of proportionality. To determine the value of K, 338 heartbeats obtained from 8 dogs under a wide range of hemodynamic conditions were analyzed. The relationship between APQ and Im(W) remained highly linear (r = 0.98), and the pooled value of K was -1.19 +/- 0.01. For the individual dogs, values of K differed at most by +/- 9% from its average value. There was also a small offset in the relationship between APQ and Im(W), probably caused by truncating the calculation of Im(W) at the 10th harmonic. Ignoring the small differences in the values of K and the offset, we found that APQ still proved to be an excellent predictor of Im(W). We also found that APQ was sensitive to changes in heart rate, left ventricular stroke output, and peripheral resistance. This reflects the dependence of pulsatile energy storage on these variables and indicates that APQ cannot serve as an index for changes in just the reactive properties of the proximal arteries.
我们表明，通过压力-流量环面积（APQ）测量的功率与无功功率[Im(W)]成正比，无功功率测量近端动脉中的脉动能量存储。从分析上讲，Im(W)与APQ相差K·2π，其中K是一个假定的比例常数。为了确定K的值，分析了在广泛的血流动力学条件下从8只狗获得的338次心跳。APQ与Im(W)之间的关系保持高度线性（r = 0.98），K的合并值为-1.19±0.01。对于个体狗，K值与其平均值的差异最大为±9%。APQ与Im(W)之间的关系也存在一个小的偏移，这可能是由于在第十次谐波处截断Im(W)的计算所致。忽略K值的微小差异和偏移，我们发现APQ仍然被证明是Im(W)的一个优秀预测指标。我们还发现APQ对心率、左心室搏出量和外周阻力的变化敏感。这反映了脉动能量存储对这些变量的依赖性，并表明APQ不能仅作为近端动脉反应特性变化的指标。
