Dielectric properties of canine acute and chronic myocardial infarction at a cell relaxation spectrum. I. Experiments

Using the dielectric probe method myocardial dielectric properties were experimentally studied at a spectrum near a cell membrane relaxation frequency (from 0.2 MHz up to the microwave region). Two hours acute ischemia and 3 weeks chronic infarction canine models have been used. Myocardial resistivity related to an ion conductivity component has been reconstructed from dielectrical data. Acute myocardial ischemia (up to 2 hours) caused an increase in the myocardial resistance up to about 42% and 14% for frequencies lower and higher the cell relaxation frequency respectively. On the other hands, chronic myocardial infarction caused a 30% and 10% decrease in the bulk myocardial resistance for low and high frequencies respectively. The changes in real part (ε´) of complex dielectric permittivity of the myocardium were more pronounced at lower frequencies especially in chronic cases. Three weeks chronic canine myocardial infarction caused the decrease of ε´ of about 52% at frequency 0.2 MHz.