Effect of coronary occlusion and reperfusion on local electrical resistivity of myocardium in dogs.

The effect of coronary occlusion and reperfusion on myocardial electrical resistivity was studied in nine anesthetized open-chest dogs. Anisotropic 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 reperfusion. To measure local resistivity longitudinal (RL) and transverse (RT) 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 were confined to a 2-mm-thick epicardial layer. Control values for RL and RT were 243 +/- 32 ohms.cm and 358 +/- 45 ohms.cm (mean +/- SD, n = 9) respectively. During a 2-min LAD occlusion, RL increased gradually by 12.4% (p < 0.05) and RT by 7.8% (p < 0.05) above the preceding control values. During a 5-min reperfusion period resistivities returned towards control values, but tended to remain elevated. RL showed a slight initial further increase during the first min of reperfusion and remained significantly above control values during 3 min of reperfusion. RT returned to values not significantly different from control after about 1 min of reperfusion.