急进高原及习服后左心功能变化的超声心动图观察

Echocardiographic assessment of the changes in left heart function between subjects acutely exposed to high altitude and after hypoxic acclimatization

目的探讨健康青年男性急进高原及习服后左心功能的变化。方法根据纳入及排除标准,纳入2012年6月-8月121名成都某部健康青年男性官兵,通过超声心动图检测所有受试者在平原、进入海拔3700m高原1d及停留l周后进入更高海拔4400m 7d、50d的左心功能参数。结果健康青年男性急性高原暴露1d时,左房内径、左室收缩末容积显著减小(P<0.05),心率、左室射血分数、每搏输出量、每搏指数、心输出量、心脏指数明显增高(P<0.05),E/A明显降低(P<0.05);进入更高海拔地区习服7d后左房内径、左室舒张末期容积较急性高原暴露后显著降低(P<0.05),左室短轴缩短率明显增加(P<0.05),每搏输出量、每搏指数、心输出量、心脏指数均明显降低(P<0.05),心率、左室射血分数、E/A差异无统计学意义(P>0.05);经50d习服后左心腔减小(P<0.05),但心率、左室射血分数、心输出量、心脏指数仍显著高于平原水平(P<0.05),每搏输出量、每搏指数明显低于平原水平(P<0.05)。结论急性高原暴露后,左心可发挥明显代偿功能,心率、每搏输出量、心输出量显著增加;随着更高海拔地区的暴露和习服时间延长,左心腔变小,但经短期习服后左心收缩功能仍显著高于平原水平。

Objective To investigate the changes in left heart function of young males acutely exposed to high altitude and after hypoxic acclimatization. Methods Based on the inclusion and exclusion standards, 121 healthy young male servicemen were enrolled in present study during June to August, 2013. By echocardiography, the changes in the left heart function of subjects were measured when they were stationed at 500m altitude, one day after their entering to a region of 3700m altitude, stayed there for one week, and then on the 7th and 50th day after their further entering into the region of altitude of 4400m. Results One day after the acute exposure of the subjects to the high altitude, their left atrium diameter （LAD）, left ventricular end-systolic volume （ESV） and E/A decreased significantly （P〈0.05）, while the heart rate （HR）, left ventricular ejection fraction （LVEF）, stroke volume （SV）, stroke index （SI）, cardiac output （CO） and cardiac index （CI） significantly increased （P〈0.05）. Compared with that of one day after exposure to acute high altitude, LAD and left ventricular end-diastolic volume （EDV） decreased significantly （P〈0.05） at the 7th day after the subjects acclimatized to an altitude of 4400m, so were the SV, SI, CO and CI, but fractional shortening （FS） significantly increased （P〈0.05）. No significant difference was found in HR, LVEF and E/A （P〉0.05）. Left ventricular size was smaller than that when stationed on the plains, however, the HR, LVEF, CO and CI were significant higher than that in 500m. Conclusion Upon acute high altitude exposure, the left heart plays a very important role in acclimatizing hypoxic environment by a significantly increase of the HR, SV and CO. Left ventricular size is smaller during higher altitude exposure and prolonged acclimatization, but the parameters of left ventricular function are still higher than their levels when stayed on the plain.