The electrocardiogram of the mountaineer at high altitude.

The British Sola Khumbu Expedition of 1959, led by Mr. J. H. Emlyn Jones, had as its objective the ascent ofAma'Dablam, an unclimbed Himalayan peak 22,400 ft. high, lying some ten miles south of Mount Everest. Secondary objectives of the expedition were to investigate the changes in the heart as shown by the electrocardiogram produced by climbing at high altitude, which is the subject of this paper, and an enquiry into the nature of the heart disease to be found among the little known Sherpa population who live at an elevation of about 12,000 ft. Ama Dablam is a pinnacle of rock and ice of startling appearance (Fig. 2 and 4) which, to use Sir John Hunt's words, " appears utterly inaccessible, outrivalling the most sensational aspects of the Matterhorn" (Hunt, 1953). It lies in north-eastern Nepal, and is approached from Katmandu to within a few miles of its base by the route followed by post-war expeditions to Mount Everest (Fig. 1).