What is a Cardiac Pacemaker?

Heart rate is controlled by the movement of the heart muscle in response to chemical pulses. In healthy people, this is a normal and unconscious process that keeps the heart pumping day in and out. People with certain heart conditions may not have the systemic ability to regulate or create the pulses that make the heart pump. A cardiac pacemaker may be implanted in some patients to provide an artificial means of pulsing.

The first cardiac pacemaker was invented by a Canadian electrical engineer named John Hopps. Following extensive research, Hopps created an external version of the pacemaker in 1950, but the device was far too large to allow implantation. Subsequent technological developments over the next few years led to decreasing size of the device, until an implantable form was created in 1958 by Swedish inventor Rune Elmqvist. The tool is now a relatively common device used to relieve the symptoms of some heart abnormalities.

The essential composition of the cardiac pacemaker is a battery, a generator, and electrodes capable of sending a pulsating signal. The device is implanted in a short surgery that may be done under local anesthetic in some cases. A cardiac pacemaker can be programmed by a technician both before and after implantation, giving flexibility to alter settings for customized needs. Though battery technology has advanced considerably since the early models, pacemakers will eventually need to have batteries replaced due to drain. Changing batteries is performed on a regular schedule, usually every five to nine years, and requires a minor surgical procedure.

There are two major programming methods for a cardiac pacemaker, called “demand” and “rate-response.” Both require the device to monitor the body for any abnormalities in order to take effect. A rate-response pacemaker will slow down the electronic pulses when it detects signs of high exertion, keeping the heart rate in a normal range. A demand model will monitor the heart rate continuously, adding electrical pulses only when the heart abnormally slows or skips a beat.

Often, pacemakers are given to elderly patients with a history of heart problems, or to younger patients who are born with abnormal heart functions. It may be used to correct bradycardia, which is a slower than normal heart rate. A cardiac pacemaker may also be implanted if the patient has heart damage resulting from a heart attack. It is frequently a tool when a patient has a heart block, which is a disruption in the electrical system that controls natural heart contractions.