Files in this Data Supplement:

• Movie I - Echocardiographic cineloops of the four chamber apical view (AVI file; 34 MB), at sea level and at 3700 m. At altitude, the right chambers were dilated, the interauricular septum bulged towards the left cavities and the interventricular septum showed an abnormal motion.
• Movie II - Echocardiographic cineloops of the short axis sternal view (AVI file; 12 MB), at sea level and at 3700 m. At altitude, the left ventricle lost its normal rounded shape, with early and end systole septal flattening and abnormal motion, and change of eccentricity indexes from 0.98 to 1.04 in end-diastole and from 1.00 to 1.49 in end-systole.