Asynchronous intraventricular recovery as a basis for apparent 'supernormality'

Various mechanisms have been postulated for the supernormal phase of intraventricular conduction where relatively early impulses are conducted with normal intraventricular conduction and relatively late impulses with abnormal intraventricular conduction. The cases presented here illustrate how asynchronous recovery of conducting tissue may result in fortuitous momentary synchrony early on in the recovery phase with asynchronous conduction properties in the later phases of recovery. This will facilitate potential synchronous conduction early on in the cycle which would result in a normal QRS complex, and potential asynchronous conduction in the later phases which would manifest with a bundle branch block QRS complex.