Objective. This study sought to investigate whether low-dose dobutamine-MRI can detect residual myocardial viability in patients with chronic myocardial infarction and left ventricular dysfunction.Methods. Eleven patients with chronic myocardial infarction and left ventricular dysfunction were employed for identification of viable myocardium by cine-MRI during dobutamine infusion. All patients underwent coronary angiography and left ventriculography,18FDG-PET, MRI at rest and stress.The systolic wall thickening measured at rest and during stress was compared with the results of 18FDG- PET, respectively.Results. A significant difference of either dobutamine-induced systolic wall thickening (SWthstress) or dobutamine-induced contractile reserve (ΔSWth＝ SWthstress- SWthrest) was present between viable and scar regions (1.0±0.3 versus -0.3 ±0.1, P＜0.01; 1.0±0.3 versus -0.2±0.2, P＜0.01).

To develop a better model of isolated perfused heart, a new apparatus of "coronary artery cannula- fixed-in-aortic tube" was developed for continuous normothermic perfusion and compared to the Casalis apparatus with cold ischemia. Eight mongrel pigs with the body weight of 18 to 24 kg were divided half into two groups.All the continuous perfusion experimental hearts resumed a spontaneous heart beat and stabilized earlier than the control hearts without the need of defibrillator or pacemaker, indicating no reperfusion injury on the heart. All the experimental hearts did not show fibrillation nor stopped beating during the entire experiment, whereas the control hearts fibrillated. Two control hearts stopped beating, and only one of the two survived with the help of pacemaker.The coronary systolic, diastolic, and mean pressures were more stable with low variation in the experimental hearts than the cold ischemic control hearts. The experimental hearts consumed more oxygen than the control hearts, indicating more cardiac output.According to these results, the continuous normothermic perfusion method by the new cannula, even though with a short-period of hypothermic perfusion, provided better myocardial protection than the cold ischemia.
Animals ; Blood Gas Analysis/veterinary ; Blood Pressure ; Cardioplegic Solutions/therapeutic use ; Catheterization/*methods/veterinary ; Heart/*physiology ; Heart Rate ; Perfusion/*methods/veterinary ; Swine/*physiology/surgery