Effects of coronary ligation of the chromically sympathectomized dog ventricle

The cardiac response to acute coronary occlusion was studied after chronic ventricular sympathectomy. Infarct size was measured using nitro blue tetrazolium. In 11 control dogs, 8 dogs with ventricles sympathectomized 2 wk earlier, and 5 sham-operated dogs, mean infarct size was 20.0%, 8.9%, and 20.4% of the left ventricular weight, respectively. Infarct size in sympathectomized ventricles was significantly less than in control or sham-operated hearts (P less than 0.05). Left ventricular perfusion before and after coronary occlusion was measured in 10 controls and 7 sympathectomized ventricles using tracer microspheres. Preocclusion flow values in chronically sympathectomized ventricles were approximately 30-40% less than in controls even though arterial pressure and heart rate were no different, suggesting an increased efficiency. Furthermore, after coromanary occlusion, collateral perfusions in the central and peripheral ischemic zones of the sympathectomized ventricles were 200-400% of those in nonsympathectomized ventricles. When collateral perfusion was related to the respective preocclusion flows, the difference between control and sympathectomized ventricles was even greater. Thus, chronic ventricular sympathectomy results in reduced infarct size, and this effect may be due to a reduced flow demand as well as to an increased collateral perfusion.