Eighty patients with coronary insufficiency, with or without infarction, were studied by kinetocardiography and electrocardiography before and after the infusion of dopamine (40 patients) or isoproterenol (40 patients). Twenty healthy subjects for dopamine and 20 for isoproterenol served as controls. The basal ECG has a moderate (52.5%) sensitivity and a high (92.5%) specificity. KCG-25 has a poor (19,7%) sensitivity and a high (95%) specificity. KCG-45 has a high (76.2%) sensitivity and a moderate (50%) specificity, 25/40 healthy subjects had at least one pathological finding: either the ECG or the KCG-25 or the KCG-45. The mechanisms and the relevance of the false positives of the KCG are reviewed. In spite of different pharmacological properties, there is no statistical difference in the effect of dopamine and isoproterenol on the ECG and KCG. The KCG may be considered equivalent to the ECG, taking into account that it brings different information. The infusion of dopamine or isoproterenol induces dyskinesia in some patients with coronary insufficiency. Only two statistically significant changes were observed: dopamine increases the sensitivity of KCG-25 (up to 44.4%) and the specificity of KCG-45 (up to 95%). In selected cases the infusion of dopamine may be a useful test.

Adolescent↗

PubMedDate not supplied

[The viable myocardium: metabolic, diagnostic and therapeutic aspects].

The term stunned myocardium is used to indicate a reversible post-ischemic dysfunction of the ventricular mechanism which may persist for hours, days or weeks after the restoration of coronary flow following spontaneous or pharmacological thrombolysis, transluminal coronary angioplasty, aorto-coronary bypass and ischemic attacks. Hibernating myocardium is used to describe a depression of ventricular contractility in the presence of chronic hypoperfusion which may be reversed following revascularization as a result of aorto-coronary by-pass surgery. Three biochemical and physiopathological hypotheses are currently acknowledged to explain the phenomenon of stunning: the hypothesis of free oxygen radicals, the hypothesis related to an energy deficit and that involving a calcium overload. It is possible that oxydizing stress induced by free radicals may modify the activity of one or more sarcolemmic proteins which regulate the flow of calcium or other ions. Alterations in the transport and accumulation of calcium ions due to a Na+/Ca++ pump deficit and calcium-ATPase of the sarcoplasmatic reticle appear to be responsible for contractile dysfunction. The hypothesis concerning an energy deficit appears to be least probable since even if ATP levels are low the intracellular energy status does not appear to be a factor which limits mechanical function which may be stimulated in the absence of further variations in the content of highly energetic phosphates. There is also reduced myofibrillar creatinkinase activity. In hibernating myocardium the mechanical dysfunction is due to a metabolic and therefore contractile "down-regulation' with low myocardial energy and oxygen consumption to ensure the survival of chronically hypoperfused areas.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗