Dual-chamber pacemakers are recommended to treat symptomatic bradycardia in people with sick sinus syndrome, atrioventricular block, or both. But there are a number of special circumstances where dual-chamber pacemakers should not be used for symptomatic bradycardia.
The first of these circumstances is when the symptomatic bradycardia is caused by sick sinus syndrome, but the flow of electrical impulses between the upper and lower chambers of the patient's heart is normal. When this happens, a single-chamber pacemaker should be used. When the pacemaker is fitted to these patients, it should be attached to the upper chamber of the heart.
The second is when the symptomatic bradycardia is caused by atrioventricular block and the patient has continuous atrial fibrillation (this is a rapid and irregular beating of the upper chamber of the heart). When this happens a single-chamber pacemaker should be used, and it should be attached to the lower chamber of the heart.
Doctors should consider the risks and benefits of using a dual-chamber pacemaker for individual patients. Patients may be frail or have other medical conditions that may make a dual-chamber pacemaker unsuitable for them. For these patients, a single-chamber pacemaker should be used, and should be attached to the lower chamber of the heart.