The initiation of ventricular tachycardia and fibrillation in isolated hearts by potassium chloride.

An accelerating tachycardia ending in fibrillation can be initiated in isolated hearts by injections of KC1 after the administration of epinephrine, but not in untreated hearts. KC1 acts in two ways to do this. First, it causes an A-V block that enables epinephrine to cause a paroxysmal ventricular tachycardia. Secondly, it causes the latter to accelerate by delaying the recovery of excitability so that at least one premature systole can fall into the recoveiy phase of a preceding impulse. This event is necessary and sufficient for the initiation of a self-sustaining accelerating tachycardia that can end in fibrillation.