长期低氧暴露对健康青年男性心脏结构和功能的影响

目的 通过对长期低氧暴露下健康青年男性心脏彩超基础数据的分析比较，揭示低氧暴露下心脏结构和功能的变化特征，探索防治高原肺动脉高压及慢性高原性心脏病的临床意义。 方法 纳入37名健康青年男性，采用低氧暴露前后自身对照的方法，利用心脏彩超测量左心房内径（LAD）、右心房内径（RAD）、左心室内径（LVD）、主动脉内径（AOD）、室间隔厚度（VST）、左室后壁厚度（LVPWT）、肺动脉内径（PAD）、右室流出道内径（RVOT）、左室短轴缩短率（LVFS）、左心室射血分数（LVEF）、左室舒张早期充盈流速（LVEDFV）、左室舒张晚期充盈流速（LVLDFV）、左室舒张早期/晚期充盈流速比（E/A）和肺动脉收缩压(PASP)，进行对比分析。 结果 低氧暴露后，HR显著升高（P<0.01），LVEF、LVFS及E/A均显著降低(均P<0.01)；低氧暴露对心脏结构和功能有显著影响，低氧暴露后LAD、LVD、AOD、VST、LVPWT均显著降低（均P<0.01），RAD（P<0.05）、PAD、RVOT（P<0.01）均显著升高。低氧暴露后，56.8%的受试对象肺动脉收缩压明显增高。PAH-组在低氧暴露后LVEDFV及E/A显著降低(均P<0.01)，LVLDFV显著升高(均P<0.01)；而PAH+组在低氧暴露后LVEF、LVFS、LVEDFV及E/A显著降低(均P<0.01)，在低氧暴露前，PAH+组受试对象LVFS和LVEF均显著高于PAH-组(均P<0.05)；PAH+组△LVFS和△LVEF的变化幅度均高于PAH-组（均P<0.01）。 结论 长期高原低氧暴露可引起肺动脉压升高以及心脏结构和功能发生显著变化；低氧暴露前LVFS和LVEF基础水平较高者或更易成为PAH易感人群。

Effects of long-term hypoxia exposure on cardiac structure and function in healthy young males

AIM To reveal the characteristics of changes of cardiac structure and function under hypoxia exposure based on the analysis and comparison of basic data of cardiac echocardiography in healthy young males with long-term hypoxia exposure and to explore the clinical significance of protection against high altitude pulmonary hypertension and chronic high altitude heart disease. METHODS By setting the inclusion and exclusion criteria, 37 healthy young males were enrolled for the study and their data before and after hypoxia exposure were compared. Cardio echocardiography was used to measure left atrial diameter (LAD), right atrial diameter (RAD), left ventricular diameter(LVD), aortic internal diameter (AOD), ventricular septal thickness (VST), left ventricular posterior wall thickness (LVPWT), pulmonary artery diameter (PAD), right ventricular outflow tract (RVOT), left ventricular fractional shortening (LVFS), left ventricular ejection fraction (LVEF), left ventricular early diastolic filling flow velocity (LVEDFV), left ventricular late diastolic filling flow velocity (LVLDFV), LV early/late diastolic filling flow velocity ratio (E/A) and pulmonary artery systolic pressure (PASP). A paired samples t-test and t-test were used for comparison analysis. RESULTS After hypoxia exposure, HR increased significantly (P<0.01), LVEF, LVFS and E/A decreased significantly (all P<0.01); Hypoxia exposure had significant effects on cardiac structure and function. After hypoxia exposure, LAD, LVD, AOD, VST and LVPWT decreased significantly (all P<0.01), while RAD (P<0.05), PAD and RVOT increased significantly (P<0.01). After hypoxia exposure, pulmonary systolic blood pressure increased significantly in 56.8% of subjects. In PAH- group, LVEDFV and E/A decreased significantly (all P<0.01), and LVLDFV increased significantly (all P<0.01); In PAH+ group, LVEF, LVFS, LVEDFV and E/A decreased significantly after hypoxia exposure (all P<0.01). Before hypoxia exposure, LVFS and LVEF in PAH+ group were significantly higher than those in PAH- group (all P<0.05); The changes of △ LVFS and △ LVEF in PAH+ group were higher than those in PAH- group (all P<0.01). CONCLUSION Long term high-altitude hypoxia exposure causes the increase of pulmonary artery pressure and significant changes in the cardiac structure and functions. The subjects with high LVFS and LVEF basal levels before hypoxia exposure may be more susceptible to PAH.