title: Assessment of myocardial performance in ischaemic heart disease: from changes in left ventricular power output produced by graded-dose isoprenaline infusion.
abstract: Current clinical indices of myocardial contractility derive from concepts of muscle mechanics developed from isolated muscle experiments. Numerous simplifying assumptions are needed to apply these concepts to contractility studies in the whole heart. An alternative is to consider the heart as a pump which generates both pressure (P) and flow (Q) and to estimate its performance from the power output of its ventricles (P X Q). A method is described for measuring peak left ventricular power output in patients during routine cardiac catheterisation. The measurements have been made at rest and following inotropic challenge with gradient infusions of isoprenaline intravenously. Results from 13 patients with coronary artery disease and severe angina pectoris, who were clinically indistinguishable from one another, are reported. The patients could be grouped according to their left ventricular peak power responses to isoprenaline, although no difference could be demonstrated between them at rest. The patients who showed no increase in left ventricular power response to isoprenaline had a poor prognosis.
mesh_terms: D000328:Adult; D002395:Catecholamines / Q000097:blood; D003327:Coronary Disease / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology; D006321:Heart / Q000503:physiopathology*; D006352:Heart Ventricles / Q000503:physiopathology; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D007263:Infusions, Parenteral; D007545:Isoproterenol / Q000008:administration & dosage; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000187:drug effects
chemical_list: D002395:Catecholamines; D007545:Isoproterenol