Studies on hyperventilation; electrocardiographic changes in normal man during voluntary hyperventilation.

Any normal human being will present certain cardiac symptoms, besides the well-known tetany signs, during voluntary hyperventilation, which removes carbon dioxide. Thus a feeling of precordial oppression, in some cases increasing to proper precordial pains with eradiation to the left arm, and often accompanied by an unaccountable sensation of fear, will generally develop after 1 or 2 minutes of hyperventilation. Continued hyperventilation for another 2 or 3 minutes will, in many cases, bring about a pronounced feeling of air hunger. The above signs and symptoms are suggestive of the presence of a transitory coronary insufficiency. It therefore seems reasonable to find out whether signs of coronary insufficiency can be demonstrated electrocardiographically during voluntary hyperventilation. A number of reports have been published on electrocardiographic examinations during hyperventilation. Kronenberger and Ruffin state that they have observed flattening of the T waves in one or more leads in 8 cases during attacks of hyperventilation tetany, whereas electrocardiograms registered between these attacks presented perfectly normal conditions. These writers hold that the changes occurring during the hyperventilation are caused by an increased vagal tonus. McCance (2) has observed similar changes during attacks of hyperventilation in 2 patients, but he is unable to give an explanation of the occurrence of these changes. Lami (3), who has experimented with 25 normal subjects, has also found a flattening of the T waves together with a decrease in the heights of the R waves in one or more leads during voluntary hyperventilation. This writer is of the opinion that the changes are due to a change of position of the heart brought about by a local