Chronic Ventricular Pacing with Ventriculoatrial Conduction Versus Atrial Pacing in Three Patients with Symptomatic Sinus Bradycardia

Three patients with symptomatic sinus bradycardia due to sick sinus syndrome were treated with permanent ventricular pacing for periods rang-ing from 2.5 to 4 years. All three patients had ventriculo-atrial conduction on routine electrocardiography. Although ventricular pacing was effective, they complained of fatigue, lightheadedness, and near syncope. Hemodynamic studies revealed the presence of regular cannon waves in the right atrium as well as in the pulmonary artery wedge pressure curves. Temporary atrial pacing resulted in disappearance of the cannon waves and a significant rise in cardiac output (32–48%). After narmal atrio-ventricular conduction was confirmed by rapid atrial stimulation and His bun-dle electrocardiography, the pacing mode was changed to permanent atrial pacing on demand. The effort tolerance of the patients marked by improved, and the previ-ously mentioned symptoms disappeared. Control hemodynamic studies 9 to 12 months affer impiantation of the atrial demand pacemaker showed that the im-provement in cardiac performance was maintained.