Intermittent pseudocomplete A-V block due to A-V dissociation in presence of 2:1 A-V block.

A false pattern of intermittent complete A-V block was seen in two asymptomatic patients when A-V dissociation was superimposed on a basic 2:1 A-V block. Although the conduction disturbance occurred at the A-V nodal level in both cases, in Case 2 it resembled A-V block due to bilateral or trifascicular disease. This arrhythmia was the end result of Type I (Wenckebach) block and apparently has a better prognosis than those emerging from a Type II (Mobitz) block.