[Myocardial ischemia induced by exercise. Analysis of the recovery phase. Behavior of the rate-pressure normalization product in patients with fixed ischemic threshold and patients with variable ischemic threshold]. / Studio dell'ischemia miocardia indotta dallo sforzo. Analisi della fase di recupero. Comportamento del doppio prodotto di normalizzazione nei pazienti con soglia ischemica variabile e nei pazienti con soglia ischemica fissa.

Traditionally, in patients with exercise-induced myocardial ischemia we analyze the stress-test by studying the behaviour of double product at ischemia. We recognize the presence of a functional component in the reduction of coronary-flow reserve if the double product at ischemia (DPI) varies in 3 stress-tests i.e. more than 20% or more than 3200 mmHg b m'-1. Any analysis that relies exclusively on double product at ischemia is, of necessity, limited to the beginning of the ischemic phenomenon. To better understand the development of the whole event, we also considered the double product calculated when the ischemic electrocardiographic signal regressed (double product of normalization: DPN). More specifically, we set out to determine whether or not double product at ischemia behaviour in patients with variable ischemic threshold (i.e. double product at ischemia variation greater than 3200 mmHg b m'-1) differs from that of patients with fixed ischemic threshold (i.e. double product at ischemia variation less than b m'-1). We performed four multistage bicycle ergometer tests, without drugs, on 19 patients with chronic exertional anginal and exercise-induced ST depression. Patients were tested at the same time of day, within a 10 day period. In the second, third and fourth stress test double product at ischemia was calculated. On the basis of double product at ischemia values in three stress-tests, we distinguished two groups.(ABSTRACT TRUNCATED AT 250 WORDS)