Endocardial activation in patients with coronary artery disease: effects of regional contraction abnormalities

Endocardial mapping was performed on 16 patients undergoing coronary artery bypass surgery, and the results were correlated with ventriculography. Bipolar electrograms were recorded from 25 to 30 left ventricular (LV) endocardial sites by a specially designed probe which was inserted through the LV vent. Electrograms were evaluated for timing and presence of fragmentation. Five patients had normally contracting ventricles, four had areas of hypokinesis, six had areas of akinesis, and one had an area of dyskinesis. In each patient earliest endocardial activation was in the septum, most often the middle portion. Latest activation was in the lateral basal area in 13 patients and in the lateral apical area in three patients. Fragmented electrograms were not found in any normal or hypokinetic zones but were found in three of six akinetic segments, and in the one dyskinetic segment. These findings describe endocardial activation of the LV and the changes seen with regional contraction abnormalities.