To assess the changes of cardiac structure and function after acclimatization at different altitudes on the plateau.

A total of 302 personnels at different altitudes on the plateau were included in the study between June 2021 and July 2021. According to different altitudes, they were divided into group A (2500 m-3000 m group, n=78), group B (3001 m-4000 m group, n=49), and group C (4001 m-5000 m group, n=175). Echocardiography was performed by an experienced sonographer, and the parameters of cardiac structure and function were measured using portable echocardiography in a quiescent state.

The end-diastolic diameter of the left ventricle and left atrium decreased with increased altitude, while the end-diastolic diameter of the right ventricle, the thickness of the free wall of the right ventricle, and the area of the right atrium increased with altitude; the parameters of group A was statistically different from those of groups B and C (P＜0.05). Parameters of right ventricular systolic function, including tricuspid annular plane systolic excursion and peak systolic velocity of the tricuspid annulus (s) were similar in the three groups. The left ventricular systolic function parameters left ventricular ejection fraction and left ventricular fraction shortening did not differ significantly among the three groups either. Mitral and tricuspid flow E waves and E/A ratios decreased, while A waves increased with higher altitude; the parameters of group A were statistically different from those of groups B and C (P＜0.05). The changes of tissue Doppler parameters including E wave, A wave, and E/A ratio were consistent with those of the power Doppler parameters. The percentage of patients with E/A inversion of the tricuspid annulus was statistically different between group A and group C (P＜0.05), and the percentage of patients with tissue Doppler e/a inversion of the tricuspid annulus was statistically different among the three groups; these changes of E/A inversion and e/a inversion were similar in the three groups (P＞0.05). The mean pulmonary artery pressure also increased with higher altitude, and there were statistical differences among these three groups (P＜0.05).

Upon chronic high altitude exposure, there are no changes of systolic function parameters of both the left and right ventricle, while the cardiac structure and diastolic function parameters are varied in different high altitude. Portable color Doppler ultrasound is a feasible method to evaluate the changes of cardiac morphology, structure, and function in high-altitude areas.