Devices That Make A Difference (Pacemakers & defibrillators)

Pacemakers and defibrillators are devices commonly implanted in the heart to treat specific malfunction of the heart’s natural electrical system, allowing patients to lead a better, safer lifestyle and, in many cases, prolong lives.

Pacemakers and defibrillators consist of a pulse generator and attached leads. The pulse generator is a small metal case containing sophisticated programmable circuitry and the lithium-ion battery. To install the pulse generator, a small incision is made on the front of the chest wall, just underneath the collarbone, not inside the chest cavity. The incision creates a pocket to install the pulse generator with one, two, or three leads attached to it. The leads are inserted into the big vein underneath the collarbone, following the vein to the heart cavity. Your cardiologist will decide the number of leads you need. Most patients have two leads; one goes to the top chamber of the heart (the atrium), and one goes to the lower chamber (the ventricle). Typically, this is an outpatient procedure with the patient going home the same day.

The lithium battery can last up to 12 years, depending on how often it is used. When the battery needs replacement, it is then taken out through a small incision, and a new battery is attached to the old leads.

A pacemaker monitors conditions causing a slow heart rate. The implanted pacemaker watches the heart rhythm all the time and intervenes only if the heart rate slows down. If a slow heart rate is detected, the pacemaker sends a very small electrical impulse stimulating the heart to trigger a heartbeat. This electrical impulse drives the heart to keep going at the desired rate. If the heart beats fast, the pacemaker will not do anything, but it will continue monitoring the heart rate all the time.

A defibrillator functions exactly like a pacemaker, but it is also programmed to recognize a life-threatening fast heart rhythm. The defibrillator delivers a high-voltage electrical shock that terminates a serious and life-threatening heart rhythm. Because a defibrillator provides a high-voltage shock, its battery and pulse generator are larger.

Which device a patient needs is decided by your cardiologist. In general, if the heart muscle is weak, the patient needs a defibrillator. If the heart muscle is not weak, a pacemaker is used.

Recent technological advancements have made it possible to create tiny pacemakers implanted inside the heart cavity. This type of pacemaker has no leads, and the device itself functions as a battery and a lead. This type of leadless pacemaker is used for particular conditions and is not suitable for every patient. The battery of the leadless pacemaker can last up to 10 years.

All cardiac devices require close follow-up, which is usually performed in the office and remotely from home. A home monitoring unit sits in the patient's bedroom and communicates wirelessly with the implanted device. This report, generated by communication between the device and the unit at home, could then be sent to the cardiologist's office through the internet.

Thanks to the evolution of technology in pacemakers and defibrillators, many patients can live a long and fruitful life that would have otherwise been cut short without it.

Dr. Sam Rahman specializes in cardiac rhythm devices at MUSC Florence Medical Center. For more information, please call his office, MUSC Health – Cardiology, at 843-674-4787.