彩色多普勒超声心动图评价急速进藏新兵心功能变化

EVALUATION OF CHANGES IN CARDIAC FUNCTION OF THE RECRUITS AFTER RAPID REACHING TIBET BY COLOR DOPPLER ECHOCARDIOGRAM

目的研究高原低氧环境对急速进藏新兵心功能及血流动力学变化的影响 ,为指导部队科学制订高原训练计划 ,预防和减轻高原反应提供科学依据。方法随机选择 6 0名乘飞机进藏的内地新兵 ,应用彩色多普勒超声心动图于进藏后第 1、2、3、4、12周分别进行 2 7项心功能及心内血流参数 ,包括左心室容量、整体收缩功能及舒张功能、心室内径及室壁厚度、各瓣口峰值流速等的检测。根据体表面积将所测数值与平原对照值进行对比研究。结果 (1)进藏第 1周即出现左心室收缩功能指标下降 ,第 4周达到最低值 (P <0 .0 1) ,直至第 12周仍未恢复到平原对照水平 (P <0 .0 5 ) ;(2 )左心室舒张功能始终无明显变化 ;(3)反映心脏结构的指标 (LVDs、LVPWd、RVDd、PAD)随进藏时间延长呈逐渐增厚增宽趋势 ;(4 )进藏第 1周始主动脉瓣峰值流速下降 ,肺动脉瓣及三尖瓣前向血流峰值流速持续加快 (P <0 .0 5 ) ;随训练强度加大两瓣口返流出现率由进藏第 1周的 5 3.3%增加到 95 .0 % ,返流量亦随之增多。结论高原低氧环境对急速进藏新兵早期心功能及血流动力学的影响以左心室收缩功能下降及右心室前负荷加重为主要特征 ,这种影响在进藏后第 4周内最为明显 ,说明心功能在第 1个月内处于调节性适应 ,此间不宜进行强度训练。

Objective To investigate the cardiac function and hemodynamics of the recruits got into Tibet without preconditioning, so as to provide scientific basis for making proper program of training to prevrent from mountain sickness. Methods Sixty recruits got into Tibet by plane were selected randomly. Twenty-seven parameters of the cardiac function and the velocity of blood flow in heart including left ventricular volume,ventricular systolic and diastolic function,diameter of ventricle, thickness of ventricular wall, and the peak flow velocity of each valve etc were obtained by using color doppler echocardiogram. These examinations were performed in the 1st, 2nd, 3rd, 4th, and 12th week after the recruits reached Tibet. According to the body surface area, the data obtained was calculated and compared with those at plain. Results (1) The left ventricular systolic function began to decrease in the lst week and reached the lowest level in the fourth week (P<0.01). After twelve weeks, it still did not recover to the level of plain (P<0.05). (2) The left ventricular diastolic function had no significant change. (3) The indexes of cardiac structure (LVDs, LVPWd, RVDd,PAD) showed that the heart became thickening and widening gradually with time (P<0.01). (4) The peak flow velocity of the aortic valve was decreased, the peak velocity of front direction flow of tricuspid valve and pulmonary valve were increased from the first week (P<0.05). The rate of occurrence of reversed flow of pulmorary valve increased from 53.3% in the lst weak to 95.8% in the 12 th week as traiming intensity increased. Conclusion Hypoxia at the altitude induced obvious early changes of the cardiac function and blood flow in the recruits without preconditioning. The main characteristics were decrease in left ventricular systolic function and increase in right ventricular front burden. These changes obviously revealed in the 4th week after reaching Tibet, suggesting that the cardiac function was in accommodation in the first month,so it is not suitable to train the recruits with high intensity during that time. Color doppler echocardiogram can get the subtle changes of the cardiac function parameters in time therefore it is the best method for cardiac function examination at the altitude.