A pacemaker is a special wire that is inserted into the patients heart. It is inserted through a central venous catheter, and usually positioned with the tip of the wire in the right ventricle (lower right chamber). The wire has a positive and negative electrode at the tip. We generally insert temporary patients in critically ill patients. If needed, a permanent pacemaker can be inserted prior to discharge home.

The pacemaker is connected to a pulse generator, which is a type of battery. The generator (or pacemaker "box") sends a stimulus to the heart, causing it to produce a heart beat. The pacemaker can be programmed to watch for the patients own beat (called "sensing"), and to pause if the patient has his or her own beat. If the patient fails to produce a beat on their own, the pacemaker will "fire" and the stimulus will produce a "paced heart beat".

Pacemakers are also available that can stimulate the patient's heart through electrodes placed on the chest wall. This type of pacemaker is called a "transcutaneous pacemaker" (through the skin). It is generally used for very short periods of time, as it is less comfortable for the patient.