Influence of Amyl Nitrite Inhalation on the Systolic Time Intervals in Normal Subjects and in Patients with Ischemic Heart Disease

The systolic time intervals of the left ventricle in 30 patients with ischemic heart disease but without heart failure were compared with those of 30 normal individuals before and after inhalation of amyl nitrite by using polygraphic recordings. In the normal subjects, following amyl nitrite, the ejection-time index was significantly prolonged, and the pre-ejection period and its index were significantly reduced, while the ejection time was not significantly shortened. The ischemic heart disease group, however, exhibited no significant changes in the ejection-time index, pre-ejection period, or its index, whereas the ejection time was significantly shortened. These differences were not related to heart rate or diastolic blood pressure level but may be explained by a postulated lack of increase in stroke volume or in the contractility of the ischemic myocardium, or both, at the maximal effect of amyl nitrite. The responses of the left ventricular systolic intervals to amyl nitrite may prove useful as a clinical test of latent ventricular functional impairment in subjects with ischemic heart disease.