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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS, RESULTS. Meshes: Animals, Dogs, Gadolinium, Hemodynamics, Myocardial Contraction, Myocardial Stunning, Premedication.
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Does gadolinium attenuate regional stunning in the canine heart in vivo? Context: Gadolinium, a lanthanide cation, ameliorates pathophysiologic features of both heart failure and cardiac arrhythmias. We have shown, in an in vitro model, that gadolinium blocks stretch-induced contractile dysfunction in both normal and stunned myocardium. The present study tested the hypothesis that gadolinium would also attenuate regional myocardial stunning in an in vivo model. Mongrel dogs (n = 13) were subjected to regional myocardial ischemia (occlusion of the left anterior descending coronary artery) for 15 minutes, followed by reperfusion for 180 minutes. Intravenous gadolinium (500 micromol) was given to 7 dogs before ischemia; no gadolinium was given to control animals. Regional contractile function was assessed serially by means of both systolic shortening (percentage) and regional preload recruitable stroke work. Administration of gadolinium before ischemia had no effect on heart rate, arterial blood pressure, stroke volume, or regional contractile function. Ischemia resulted in paradoxical systolic bulging in both groups. After 180 minutes of reperfusion, systolic shortening was enhanced in gadolinium-treated animals compared with that in control animals (10.9% +/- 1.5% vs 2.4% +/- 1.7%, P =.003). Both the slope and x-axis intercept of regional preload recruitable stroke work returned to preischemic values in treated animals but remained abnormal in control animals.
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These data confirm that gadolinium attenuates regional myocardial stunning in vivo. Gadolinium may cause peripheral vasodilatation but does not appear to exert positive inotropic effects on the normal canine heart. The mechanism underlying gadolinium-mediated effects on stunned myocardium remains undefined, but this study suggests that use of gadolinium may represent a novel adjunct to current cardioprotective strategies. Final Decision: yes