Atrioventricular plane movements under head down tilt position of simulated weightlessness: an analysis by quantitative tissue velocity imaging
AIM: To explore the influence of head down tilt position of simulated weightlessness on the movements of the atrioventricular plane by quantitative tissue velocity imaging (QTVI) and to elucidate the influence of simulated weightlessness on left cardiac function. METHODS: Sixteen healthy male volunteers were involved in this research and weightlessness was simulated by lying in bed with - 6 degree head down tilt position. QTVI was adopted to observe the movements of atrioventricular plane before simulated weightlessness as well as 10 d and 20 d during simulated weightlessness and six sample points of the atrioventricular plane were recorded from apical four-cavity view,apical two-cavity view and left ventricular long-axis view. The indices of QTVI including the peak velocity in systolic phase ( Vs),early diastolic phase (Ve),late diastolic phase (Va) and the ratio of Ve to Va were processed with SPSS 11.0. RESULTS: No significant changes in Vs were observed during simulated weightlessness. Ve decreased in 3 sample points on the 10th day and in 5 sample points on the 20th day during simulated weightlessness ( P <0. 05 ). Ve of the posterior septal point decreased significantly on the 20th day compared with that on the 10th day during simulated weightlessness (P<0. 05). Va decreased significantly in lateral wall's sample point on the 20th day during simulated weightlessness (P < 0.05) and the ratio of Ve to Va of anterior and posterior septal point also decreased significantly on the 20th day during simulated weightlessness ( P < 0. 05 ). CONCLUSIONS: Simulated weightlessness degrades cardiac diastolic function and this effect aggravates with the time prolongation of simulated weightlessness. But,simulated weightlessness has no effect on cardiac systolic function.
NETL
NSTL
万方数据
维普
