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.