正常人Valsalva动作张力期左心室充盈变化及其力学机制

Changes of left ventricular filling during the strain phase of Valsalva maneuver in healthy subjects and its mechanism

目的探讨正常人Valsalva动作张力期左室充盈变化及其机制。方法超声心动图观测30例正常人初始时、Valsalva动作张力期第1个心动周期及第2个心动周期时左室充盈指标（E、A、E／A、e及E／e）的变化。结果与初始时比较，第1个心动周期时E、E／A及E／e增大（P〈0．05）；与第1个心动周期比较，第2个心动周期时E、E／A及E／e减低（P〈0．05）。结论正常人Valsalva动作张力期第2个心动周期时左室充盈即减低，这与以往认为张力期4～5个心动周期后左室充盈开始减低不同。胸内正压降低左心系统与回流肺静脉跨壁压力，增加血流阻力可能是其原因。

Objective To explore changes of left ventricular filling during the strain phase of Valsalva maneuver （VM） and its mechanism. Methods Thirty healthy volunteers were recruited to perform VM with a load of 40 mmHg. Left ventricular filling parameters （E, A, E/A ratio, e and E/e ratio） were determined by echocardiography at baseline,at the first beat and at the second beat during the strain phase of VM,respectively. Results Compared to those at baseline, E, E/A ratio and E/e ratio increased （ P 〈 0. 05） while A and e did not change （ P 〉0.05） at the first beat during the strain phase. Compared to those at the first beat during the strain phase,E,E/A ratio and E/e ratio decreased （ P 〈0. 05） while A and e did not change （ P 〉 0. 05） at the second beat during the strain phase. Conclusions Left ventricular filling decreased at the second beat during the strain phase of VM, which is different from the present knowledge that left ventricular filling would begin to decrease 4-5 beats later during the strain phase of VM. Positive intrathoracic pressure decreases left-side heart and pulmonary vessel＇ transmural pressure while increases the blood resistance,which may be the reason that E, E/A ratio and E/e ratio decreased at the second beat during the strain phase of VM.