Sinoventricular conduction during acute myocardial ischemia.

A case with sinoventricular conduction and sinus bradycardia during unstable angina pectoris is presented. Although His bundle electrogram showed atrial and His bundle deflection no P waves could be observed in any surface leads even when effective high right atrial pacing was performed. It may be assumed that the electric or sinus impulses are conducted over the specialized atrial tracts while atrial muscle is in a refractory state due to myocardial ischemia.