Sinus Node Dysfunction AV Block Neurally Mediated Syncope or Carotid Sinus Hypersensitivity Single-chamber atrial pacemaker No suspected abnormality of AV conduction and not at increased risk for future AV block Maintenance of AV synchrony during pacing desired Rate response available if desired Not appropriate Not appropriate (unless AV block systematically excluded) Single-chamber ventricular pacemaker Maintenance of AV synchrony during pacing not necessary Rate response available if desired Chronic atrial fibrillation or other atrial tachyarrhythmia or maintenance of AV synchrony during pacing not necessary Rate response available if desired Chronic atrial fibrillation or other atrial tachyarrhythmia Rate response available if desired Dual-chamber pacemaker AV synchrony during pacing desired Suspected abnormality of AV conduction or increased risk for future AV block Rate response available if desired AV synchrony during pacing desired Atrial pacing desired Rate response available if desired Sinus mechanism present Rate response available if desired Single-lead, atrial- sensing ventricular pacemaker Not appropriate Normal sinus node function and no need for atrial pacing Desire to limit the number of pacemaker leads Not appropriate

AV indicates atrioventricular.