The objective of the assessment was to estimate the effectiveness and cost-effectiveness of dualchamber pacemakers versus single-chamber atrial or single-chamber ventricular pacemakers in the treatment of bradycardia due to sick sinus syndrome (SSS) or atrioventricular block (AVB).
A pacemaker consists of a small, battery-powered generator and one or more leads. In a singlechamber system, one lead is used, most commonly pacing the right ventricle. Dual-chamber pacemakers have two leads, placed in the right atrium and right ventricle. They act synchronously when a slow natural heart rate is detected to mimic the sequential physiological contraction of the atria and ventricles. Single-chamber pacemakers may be atrial or ventricular. Atrial pacemakers are used where slow heart rate is due only to sinoatrial disease, i.e. where conduction between the atria and ventricles is intact. Single-chamber ventricular pacemakers, which are much more commonly used in practice, are appropriate where conduction between the atria and ventricles is impaired.