呼吸对正常犬血流动力学影响的超声心动图研究

目的研究正常自主呼吸胸压变化对血流动力学的影响,进一步探讨呼吸影响心功能的机制.方法 11条心功能正常杂种犬,使用Acuson Sequoia 512彩色电脑声像仪,同步记录心电图、呼吸曲线和心内各瓣口血流速度,观察瓣口血流速度随呼吸变化的规律.结果三尖瓣和肺动脉瓣口血流速度随呼吸周期呈现规律性变化,但二尖瓣和主动脉瓣口的血流在部分呼吸周期中的变化并无明显规律,峰值血流速度出现与呼吸时相间有不确定性.结论自主呼吸所引起的胸压变化使室间隔左右摆动,但由于肺组织本身弹性的差异,胸内压和肺毛细血管内压间存在的压差使全胸内系统血液重新分布.这种血液重新分布取决于肺组织的弹性,从而导致二尖瓣和主动脉瓣口血流速度变化与呼吸时相间具有不确定性.

An Echocardiographic Study of Influences of Respiration on Hemodynamics in Normal Dogs

Objective To observe hemodynamic effects of normal respiratory fluctuation of intrathoracic pressure in dogs and to study the mechanism of respiratory influence on cardiac function Methods The variations of the blood flow velocities across the four cardiac valves were recorded with Sequoia 512 in 11 dogs with normal respiration Electrocardiograms and respiratory tracing were recorded synchronously Results The velocities across the tricuspid valves and pulmonary valves changed regularly during the respiratory cycle,but the velocities across the mitral valves and aortic valves did not change regularly during the respiratory cycle in which the maximum velocity did not appear in a definite time phase in the respiratory cycle Conclusions Fluctuation of normal respiratory intrathoracic pressure led to ventriclar septum swing On the other hand there was pressure gradient between the intrathoracic pressure and alveolar pressure due to lung compliance,which resulted in redistribution of alveolar blood flowing to the left ventricle These two factors accounted for the uncertain relationship between blood flow velocities at the mitral and aortic valves and the respiratory cycle