Retrograde conduction from artificial pacemaker to atria in sick sinus syndrome.

The influence of retrograde conduction of the artificial pacemaker impulse from the right ventricle to the atria exerted upon the occurrence of rapid supraventricular rythms was investigated in patients with sick sinus syndrome. The bouts of tachycardia occurred in cases with fixed V-A retrograde block or coincided with temporary V-A block. The usually operating retrograde conduction from the pacemaker to the atria protects the patients from paroxysms of supraventricular tachycardia by means of the coordinated depolarization of the atria and junctional tissue.