We studied the difference between myocardial vulnerability to arrhythmias caused by cathodal, anodal, and bipolar stimulation in 29 dogs with partial right coronary artery occlusion. We used 2-msec duration stimuli of up to 8 mA to determine the ventricular vulnerable periods, their relationship to the refractory periods, and the fibrillation or multiple response thresholds for unipolar anodal ...