Ha B, Lucas C L, Henry G W, Frantz E G, Ferreiro J I, Wilcox B R
Department of Cardiothoracic Surgery, University of North Carolina at Chapel Hill 27514.
Am J Physiol. 1994 Jul;267(1 Pt 2):H155-65. doi: 10.1152/ajpheart.1994.267.1.H155.
The effects of pulsatile hemodynamics on right ventricle-pulmonary circulation interactions were studied in control lambs and in two lamb models of altered pulmonary hemodynamics induced at infancy: elevated pulmonary arterial pressure (PAP) was created by the infusion of monocrotaline pyrrole (MCTP), and elevated pulmonary arterial blood flow was obtained by the creation of an arteriovenous fistula (Shunt). High-fidelity PAP, midvessel Doppler blood velocity (PAV), and cardiac output (CO) were measured in open-chest, anesthetized lambs. PAV waveforms were normalized to match the measured CO. Measured pressure and flow signals were separated in the time domain into forward and backward components. Pulmonary input impedance and indexes quantifying the timing of the reflected wave pulse (beginning of reflected pulse, duration of reflected pulse in systole, and duration of reflected wave in diastole) were calculated for each group. Results indicate that in control animals the reflected wave returned late in systole and extended through much of diastole, thereby increasing diastolic pressure like a counterpulsation balloon. No significant differences in the timing indexes were found between Shunt and control animals. In the MCTP group, the reflected wave returned significantly earlier than normal with the peak reflected pulse occurring before valve closure. The resulting augmentation of systolic pressure and, therefore, large pulse pressure is consistent with pressure waveforms observed in clinical pulmonary hypertension. We conclude that early wave reflection exerts a detrimental effect in pulmonary hypertension by unfavorably loading the still-ejecting right ventricle.
在对照羔羊以及两种婴儿期诱导的肺血流动力学改变的羔羊模型中，研究了搏动性血流动力学对右心室 - 肺循环相互作用的影响：通过注入单氰胺吡咯（MCTP）来升高肺动脉压（PAP），通过建立动静脉瘘（分流）来增加肺动脉血流量。在开胸、麻醉的羔羊中测量高保真肺动脉压、血管中部多普勒血流速度（PAV）和心输出量（CO）。将PAV波形进行归一化以匹配测量的CO。在时域中将测量的压力和流量信号分离为正向和反向分量。计算每组的肺输入阻抗以及量化反射波脉冲时间的指标（反射脉冲开始、收缩期反射脉冲持续时间和舒张期反射波持续时间）。结果表明，在对照动物中，反射波在收缩期末期返回并延伸至大部分舒张期，从而像反搏球囊一样增加舒张压。分流组和对照动物之间在时间指标上未发现显著差异。在MCTP组中，反射波比正常情况显著更早返回，反射脉冲峰值在瓣膜关闭之前出现。由此导致的收缩压升高以及因此产生的大脉压与临床肺动脉高压中观察到的压力波形一致。我们得出结论，早期波反射通过对仍在射血的右心室施加不利负荷，在肺动脉高压中发挥有害作用。
