Effects of hyperkalemia on local changes of repolarization duration in canine left ventricle.

The effect of hyperkalemia on the distribution of ventricular repolarization properties was investigated using the interval between minimum QRS and maximum T derivatives of multiple electrograms as a measure of local repolarization duration. Local repolarization duration decreased, with more marked reduction at the epicardium than endocardium near the base, and greater decrease at the endocardium than epicardium near the apex. The nonhomogeneous reduction of repolarization duration helps account for T waveform changes due to hyperkalemia and may be a factor in the occurrence of re-entrant ventricular arrhythmias.