胸内正压对正常人左室充盈的直接影响及其力学机制

Direct effects and mechanism of positive intrathoracic pressure on left ventricular filling in healthy subjects

目的探讨胸内正压对正常人左室充盈的直接影响及其力学机制。方法超声心动图检测30例成正常人初始时与标准乏氏动作张力期10s时左室舒张早期、舒张晚期血流速度(E峰、A峰)、二尖瓣环舒张早期运动速度(e),计算左室舒张功能(E/A)、舒张早期充盈压(E/e)的变化。结果与初始时比较,标准乏氏动作张力期10s时,E峰、E/A及E/e减低,差异均有统计学意义(P<0.05)。结论胸内正压的力学作用会阻碍左室舒张运动,引起E峰及E/A减低;胸内正压增加血流阻力可能是导致E峰及E/e减低的一个原因。

Objective To explore the direct effects and mechanism of positive intrathoracic pressure on left ventricular （LV） filling in healthy subjects. Methods Thirty healthy subjects were recruited to perform Valsalva maneuver（VM） lasted for 10 s, then the early diastolic velocity （E）, late diastolic velocity （A） of LV and early diastolic velocity of mitral annulus （e） were measured, the changes of E/A and E/e were calculated. Results Compared with the rest, E, E/A and E/c were dec.reased at 10 s during the strain phase, there was significant difference （ P 〈 0. 05 ）. Conclusion Mechanical effects of positive intrathoracic pressure impede LV diastolic motion, which could cause the decrease of E and E/A ratio. Positive intrathoracic pressure increases the flow resistance of LV and pulmonary vasculature, which may contribute to the decrease of E and E/e ratio.