Optimal left ventricular loading using a realtime imprdance loading system

我们研究了脉搏波在动脉系统中的反射对心室射血的影响。为了定量评估脉冲波反射对心室射血的影响，我们以高分辨率表征了动脉系统的特性。宽频带液压抗扰性。通过傅里叶反变换（FFT），将偏移阻抗谱作为脉冲响应转换到时域。我们利用离体犬心脏制备材料，通过心室射血与心房脉冲响应的准实时卷积，实验推导出反射波。类似地，我们通过将射血流量与动脉脉冲响应进行卷积，在计算机上模拟心室射血，近似于具有时变弹性的心室。虽然反射波对瞬时心室压和动脉流量有很大影响，但它对射血量的影响较小。即，每搏心输出量，不显著。正如我们在之前的研究中指出的，至少在正常犬心脏中，心输出量和左心室外功的主要决定因素是动脉阻力，由于心室收缩减弱使得心室射血对后负荷敏感，因此不能完全排除反射波对衰竭心室的显著影响。我们显然需要进一步调查。

We investigated hnow the pulse wave reflection in the arterial system affects ventriculat ejection. To quantitatively evaluate the effects of the pulse wave reflection on ventricular ejection, we characterized the arterial system propertied in terms of high resolution. wide band hydraulic imperance. The devived impedance spectrum was transformed to the time domain as the impulse response thorough the inverse Fourier transform (FFT). We experimentally derived the reflected wav thorough the quasi-realtime convolution of the ventriculat ejection flow with the atrerial impluse response using an isolated canine heart preparation. Similarly we simulated the ventricular ejection on the computer by convolving the ejection flow with the arterial impluse response, approximating the ventricle with a time varying elastance. Although the reflected wave considerably influenced instantaneous ventrricular pressure and arterial flow, its effect on the amount of ejection. i.e., stroke volume of cardiac output, was insignificant. As we indeicated in previous studies, the major determinant of cardiac output and external work of the left ventricle was agte asll arterial resistance at least in the normsl canine heart, Since weakineng the ventricular contranction makes the ventricular ejection sensitive to afterload, the significant effect of the reflected wave on the failing ventricel cannot be totally excluded. We clearly need further investigations.