Cardiac implantable electronic device therapy for bradyarrhythmias and tachyarrhythmias.

Pacemakers originally were developed for patients with profound bradycardia and complete heart block who, without them, usually suffered from syncope, heart failure and an early demise. Since that time, devices have evolved to include pacing and shock therapies for the management of tachyarrhythmias and heart failure with the aim of improving quality, and if possible, length of life. Whether to insert a device depends on a balance between the potential benefits of device therapy and its risks, which are not inconsiderable. We discuss current agreed indications for pacemakers and implantable defibrillators and some current controversies surrounding their use.