Time course of changes in cardiac magnetic field mapping after myocardial infarction in rats

Noninvasive electrophysiological phenotyping in small rodents is usually done by ECG studies. However information content from few ECG leads is limited. We investigated how Cardiac Magnetic Field Mapping (CMFM) parameters change at different time points after myocardial infarction in rats. Therefore, myocardial infarction was induced by ligation of the anterior descending artery in male Sprague Dawley (SD) rats. CMFM recordings were done using a 7 channel SQUID system during a follow up of 4 weeks after myocardial infarction. Rats with myocardial infarction were compared with sham operated animals. Anterior myocardial infarction resulted in a significant reduction in left ventricular function and initiation of structural remodeling process. Acute myocardial infarction was associated with pronounced changes in STT segment, including elevation of magnetic field strengths and a rotation of the magnetic field orientation. CMFMs obtained within the chronic phase of myocardial infarction revealed signs of electrical remodeling by prolongation of repolarization parameters and increase in inhomogeneity of repolarization. Another characteristic finding was a progressive loss in MCG RPeak values. CMFM noninvasively detects electrophysiological changes in rats with myocardial infarction. Different alterations characterized acute ischemia and electrical remodeling, which accompanied structural remodeling in the chronic state of the disease