Atrioventricular block with 4:2 conduction pattern: concealed electrotonic conduction as an alternative mechanism

摘要

We have read with much interest a recent report by Jastrzebski and Kukla on atrioventricular (AV) block with 4:2 conduction pattern. They presented electrocardiograms showing AV block with 4:2 conduction pattern in a patient with myocardial infarction. They proposed 3 alternative explanations: (1) supernormal conduction; (2) 2-level block with 4:1 conduction ratio in the upper level and 3:2 conduction ratio in the lower level; and (3) presence of 2 populations of Purkinje cells in the remaining, critically injured, fascicle: one with the phase-3 block and the other with slow diastolic depolarization leading, during a pause after the first nonconducted P, to phase-4 block.