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如何影响脑室射血。为了定量评价脉搏波反射对心室射血的影响，我们用高分辨率表征了动脉系统的特性。宽频带液压系统。通过反傅立叶变换(FFT)将偏差阻抗谱变换到时间域作为脉冲响应。我们使用一种离体犬心脏标本，通过心脏射血流量与心脏搏动反应的准实时卷积，实验得出了反射波。类似地，我们在计算机上通过将射血流量与动脉脉冲反应卷积来模拟脑室射血，以时变的弹性近似脑室。虽然反射波对瞬时室压和动脉流量有很大影响，但对射血量的影响不大。即心输出量的每搏量是微不足道的。正如我们在以前的研究中所指出的，至少在正常犬心脏中，决定心输出量和左心室外做功的主要因素是动脉阻力，由于心肌收缩使左心室射血对后负荷敏感，因此不能完全排除反射波对衰竭左心室的显著影响。我们显然需要进一步的调查。

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.