Infarct sizing after reperfusion by two-dimensional echocardiography and serum cardiac myosin light chain II in conscious dogs: dissociation between early left ventricular wall motion and ultimate infarct size.

The time course of recovery of left ventricular wall motion after coronary reperfusion and how that relates to anatomical infarct size, wall motion abnormality, and the amount of cardiac myosin light chain II release were evaluated in conscious dogs. One week after the implantation of hydraulic occluders on the left circumflex arteries, myocardial infarction was induced. Coronary reperfusion was performed 3 h after the occlusion in 9 dogs (R) and occlusion was sustained in 9 dogs (C). All dogs underwent serial 2-dimensional echocardiograms and determination of serum cardiac myosin light chain II. The infarct size was identified at 14 days. Systolic wall thickening at the center of the ischemic area (SWT) at 3 h was -7.7 +/- 2.8% (C), -9.9 +/- 3.0% (R). Systolic thinning was observed even at 14 days in C. Significant recovery of contraction was observed in R, but the improvement continued for as long as 2 days. SWT at 14 days was -1.5 +/- 2.8% (C) and 7.0 +/- 4.6% (R) (p less than 0.05). All of SWT or the extent of systolic thinning (EST) 3-hour and 14-day were correlated well with infarct size in C. In group R, 14-day SWT and 14-day EST correlated with infarct size but 3-hour SWT and 3-hour EST did not. Total release of serum cardiac myosin light chain II levels correlated well with infarct size (r = 0.88), 14-day SWT (r = -0.90) and 14-day EST (r = 0.89) in all dogs.(ABSTRACT TRUNCATED AT 250 WORDS)