title: Response of reperfusion-salvaged, stunned myocardium to inotropic stimulation.
abstract: The purpose of this study was to determine whether myocardium salvaged by reperfusion following coronary occlusion could respond to inotropic stimulation by dopamine. Mongrel dogs underwent a 2-hour occlusion of the proximal left anterior descending coronary artery, followed by reperfusion for 5 or 28 hours. Dopamine (5 to 10 micrograms/kg/min) or dextrose was administered 1 hour or 24 hours after the onset of reperfusion. Serial, computer-assisted, two-dimensional echocardiographic determination of percentage of systolic wall thickening (%SWT) and cross-sectional ejection fraction (% delta area) were used to evaluate the response to treatment. Myocardium in the region of central ischemia contracted poorly after 1 hour of reperfusion (mean %SWT = 1.3 +/- 13.3% [mean +/- SD] compared to preocclusion value of 43.6 +/- 18.5%, p less than 0.001) and tended to thin at 24 hours of reperfusion (mean %SWT = -6.0 +/- 12.3%, p less than 0.001). After 1 hour of reperfusion, dopamine produced a greater than fourfold improvement in %SWT within the reperfused zone (to 15.3 +/- 7.3%, p less than 0.05). After 24 hours of reperfusion, dopamine again produced an improvement in %SWT (to 5.8 +/- 12.5%, p less than 0.05). There were no significant changes in %SWT with dextrose infusion. Thus, dopamine stimulates the reperfusion-salvaged but noncontracting (stunned) myocardium to contract as early as 1 hour after reperfusion.
mesh_terms: D000818:Animals; D001157:Arterial Occlusive Diseases / Q000188:drug therapy; D003326:Coronary Circulation / Q000187:drug effects*; D003331:Coronary Vessels / Q000473:pathology; D004285:Dogs; D004298:Dopamine / Q000627:therapeutic use*; D004452:Echocardiography / Q000379:methods*; D006439:Hemodynamics / Q000187:drug effects; D009200:Myocardial Contraction / Q000187:drug effects*; D013997:Time Factors
chemical_list: D004298:Dopamine