[Hyperventilation test in coronary disease: a comparison with a bicycle ergometer exercise test. Report of 100 cases].

A hundred cases have been studied and divided into three categories:--60 normal subjects;--30 coronary subjects with a positive exercise test;--10 subjects with defective nervous control of the circulation; using the exercise test, we studied the effects of hyperventilation on repolarisation of the ventricle. In the normal subjects there was no ischaemic depression of the ST segment, but there were minor changes in repolarisation which affected the T wave in 73% of subjects and were essentially posterior in distribution. In the coronary subjects, we found three with ischaemic depression of the ST segment and one with ST elevation of 2.5 mm (6.7% of the coronary subjects). This last finding is evidence against the commonly held hypothesis that reproduction of ST depression by hyperventilation during the exercise test indicates a false positive test. In the patients with defective nervous control of the circulation, 9 had an ischaemic type of ST depression, either as a new feature or as a more severe one compared with that found at rest. The mechanism by which these depressions are produced has not been totally explained:--in the cases with defective nervous control of the circulation, it appears that latent increased sympathetic activity is increased by the hyperventilation;--in the coronary subjects, it may be caused by true ischaemia or by an associated defect in nervous control of the circulation.