Role of some components of ischemia in the genesis of spontaneous ventricular arrhythmias.

The importance of single components of ischemia including hypoxia, lactic acidosis, high potassium, and sympathetic stimulation to the spontaneous occurrence of ventricular arrhythmias was studied in chloralose-anesthetized cats using systemic and local intracoronary administration. Hypoxia and acidosis provoked no spontaneous arrhythmias regardless of systemic or regional administration. Systemic or local hyperpotassemia induced regularly ventricular ectopic activity including recurrent ventricular tachycardias that were characterized by a sudden onset and termination and by a stable rate. Stimulation of the left, right or bilateral stellate ganglia failed to provoke ventricular arrhythmias during hypoxia or acidosis and had also no influence on the initiation or rate of K+-induced ventricular tachycardias. The results indicate that high extracellular K+ may be the predominant arrhythmogenic factor of the components of ischemia we studied and that sympathetic ganglia stimulation does not affect K+-induced ventricular tachycardia.