Relationship of systolic dysfunction to area at risk and infarction size after ischemia-reperfusion in mice.

Whereas the extent of wall-motion abnormality (WMA) correlates well with the area at risk (AAR) and infarction size in murine models of nonreperfused myocardial infarction, this relationship is less clear in the setting of ischemia-reperfusion injury. Echocardiography was performed in mice at baseline, after left anterior descending coronary artery ligation (30 minutes) followed by reperfusion (24 hours), and after religation of the left anterior descending coronary artery. The extent of WMA before and after religation was compared with the initial infarction size measured by triphenyltetrazolium chloride and the AAR measured by fluorescent microspheres, respectively. Echocardiography showed left ventricular dilation and dysfunction after ischemia and reperfusion. WMA after religation correlated well with AAR (r2 = 0.70, P <.0001). The correlation between WMA and infarction size was incomplete (r2 = 0.59, P <.0002) in part because of underestimation of nontransmural infarcts. Echocardiography can reliably assess AAR after ischemia-reperfusion in mice; however, it does not allow for precise quantification of the small areas of necrosis that often occur in this setting.