Changes in Electrocardiogram Among Temporary Residents at High Altitude

A prospective study was conducted on young healthy men who were residents of plains and stayed at high altitude for 24 months-the first 12 months at an altitude of 4,200 metres and subsequent 12 months at 3,600 metres.Their ECGs were recorded in the plains before departure for high altitude and after 3, 6, 11, 18 and 23 months of stay at high altitude. After their return tothe plains further ECG examinations were carried out after 1, 3 and 6 months of return. ECG changes suggestive of right ventricular hypertrophy were present in a substantial number of individuals after three months of arrival and they persisted during their stay at high altitude. The ECG changes reversed completely in majority of individuals within one month of return to plains. These changes are considered to be due to hypoxia and are reversible.