EFFECT OF CORONARY-OCCLUSION AND REPERFUSION ON LOCAL ELECTRICAL-RESISTIVITY OF MYOCARDIUM IN DOGS

The effect of coronary occlusion and reperfusion on myocardial electri cal resistivity was studied in nine anesthetized open-chest dogs. Anis otropic resistivity was measured on the anterior free wall of the left ventricle (LV) before (control) and during transient occlusion of the left anterior descending (LAD) coronary artery, and during reperfusio n. To measure local resistivity longitudinal (R(L)) and transverse (R( T)) to epicardial muscle fiber direction, a sensor was developed based on the four electrode (FE) technique with an electrode distance of 1 mm. Previous calculations showed that measurements with this system we re confined to a 2-mm-thick epicardial layer. Control values for R(L) and R(T) were 243 +/- 32 OMEGA . cm and 358 +/- 45 OMEGA . cm (mean +/ - SD, n = 9) respectively. During a 2-min LAD occlusion, R(L) increase d gradually by 12.4% (p < 0.05) and R(T) by 7.8% (p < 0.05) above the preceding control values. During a 5-min reperfusion period resistivit ies returned towards control values, but tended to remain elcvated. R( L) showed a slight initial further increase during the first min of re perfusion and remained significantly above control values during 3 min of reperfusion. R(T) returned to values not significantly different f rom control after about 1 min of reperfusion.