Cardiac arrhythmias in sensitized hearts - primary mechanisms involved.

The primary locus of the sensitizing action of hydrocarbon anesthetics to the arrhythmogenic action of catecholamines has now been shown to be the heart itself. It has been demonstrated in the completely isolated heart perfused with an artificial medium. The induction of ventricular arrhythmias, which begins with a shift in the site of the primary pacemaker from the sinus node to the A-V junctional area, requires the development of a significant intraventricular pressure. It is facilitated by a marked reduction in the refractory period of Purkinje fibers with little concomitant effect on regular myocardial fibers.