Artificial pacemakers generate a rhythm via electrical leads placed in the atrium and/or ventricle(s) of the heart. They usually create a short sharp pacemaker spike on the ECG, though this can be hidden by some filter settings.

Pacemakers can be classified by the code developed by the North American Society of Pacing and Electrophysiology (NASPE) and the British Pacing and Electrophysiology Group (BPEG).

Chamber(s) paced Chamber(s) sensed Response to sensing Rate modulation Multisite pacing
O = None O = None O = None O = None O = None
A = Atrium A = Atrium T = Triggered R = Rate modulation A = Atrium
V = Ventricle V = Ventricle I = Inhibited V = Ventricle
D = Dual (A+V) D = Dual (A+V) D = Dual (T+I) D = Dual (A+V)

Common pacemakers include AAI (atrial sensing and pacing on demand), VVI (ventricular sensing and pacing on demand) and DDD (dual atrial and ventricular sensing, either can be paced on demand). Other varieties include biventricular and Implanted Cardioversion Devices (ICD).

Pacemakers can be used to treat many arrhythmias, including second or third degree AV block, sick sinus syndrome, multiple conduction blocks and tachyarrhythmias.