Body surface map patterns of altered depolarization and repolarization in right bundle branch block.

Surface maps from 14 patients with right bundle branch block were analyzed throughout depolarization and repolarization. The abnormalities in depolarization found in all the subjects were 1) epicardial breakthrough that was delayed and shifted to the left, and 2) development of right upper anterior positivity during the midportion of depolarization. In eight patients, this positivity manifested as multiple peaks, suggesting a fragmented spread of depolarization. We believe these findings result not only from the delayed engagement of the right ventricle by the conduction process, but also from its nonuniform and dyssynchronous spread. The recovery phase displayed five abnormal patterns: 1) simultaneous negativity on the right and positivity on the left of the midline in six patients; 2) only negativity on the right of the midline in four; 3) only positive potentials in the left upper chest in two; 4) only negative potentials on the left side of the midline in one; and 5) negative potentials spread diffusely over the precordium in one. The different degrees of this altered repolarization, we believe, depend upon the degrees of altered sequence of activation of the heart in addition to the changes produced by the underlying disease process.