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

Abstract

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.

Acute haemodynamic effects of a new calcium antagonist, nicardipine, in man. A comparison with nifedipine.

“…We assume that the LVET-I increase in our study is mainly the result of increased stroke volume. This is supported by the findings of Sawayama et al (1969) who showed that amyl nitrite, which decreases both pre-load and after-load, shortens LVET-I.…”

Effects of Procainamide and N-Acetylprocainamide on Myocardial Contractility in Ischemic Isolated Rabbit Hearts

“…(6) have reported significant increases in preejection period index (PEPI) and decreases in preejection period/left ventricular ejection time ratios using carotid pulse tracings. These changes are consistent with improved contractility, however, systolic time intervals are also influenced by peripheral resistance and positive changes do not necessarily reflect direct inotropic effects (10). That NAPA has an indirect effect on myocardial contractility has been proposed by Lertora et al (14) to explain their observations of a failure of NAPA to improve normal systolic time intervals.…”

Systolic time intervals: a review of the method in the non-invasive investigation of cardiac function in health, disease and clinical pharmacology

“…Deviations in LVEDP may occur during pharmacological interventions. Reduction in peripheral resistance (Harris et al, 1967;Sawayama et al, 1969) results in shortening of PEP, while increase in peripheral resistance by angiotensin (Harris et al, 1967) and methoxamine (Shaver et al, 1968) prolongs PEP. PEP also depends on the myocardial contractility and inotropic state, so it is prolonged in heart failure (Weissler et al, 1968) and myxoedema (Crowley et al, 1977).…”

“…During methoxamine infusion, when SV, heart rate and inotropic state were held constant, LVET increased as mean arterial pressure increased (Shaver et al, 1968). Decrease in afterload prolongs LVET (Sawayama et al, 1969) due to the augmented stroke volume.…”