Disturbances of transmembrane ionic fluxes and their role in the pathogenesis of cardiac dysrhythmias

Abstract

Abnormalities of cardiac rhythm are due either to disorders of impulse propagation (delay or block of conduction, re-entry, circus movement, etc.), or to disturbances of impulse formation (dysfunction of ordinary pacemakers and induction of focal activity). In most instances certain disturbances of transmembrane movements of Na or K ions may be considered to be involved basically in the genesis of dysrhythmic cardiac activity. By means of intracellular recordings as well as of voltage clamp measurements and of analogical computations it is demonstrated that characteristic changes of the membrane potential might result from entirely different ionic mechanisms. Furthermore, an attempt is made to present a detailed analysis of permeability changes underlying normal pacemaker activity in Purkinje fibers as compared with the sinus node or with focal activity induced in myocardial fibers by different influences (aconitine, barium ions, stretch, and strong currents).