The Difference between Pacemakers
and Implantable Cardioverter Defibrillators


While you have no doubt heard of pacemakers and you probably know what a defibrillator is, there’s a good chance you are not familiar with the implantable cardioverter defibrillator unless you or someone you love has experienced cardiac arrest.

Unlike the emergency defibrillator devices found in many hospitals, workplaces, schools and other public locations that is used to deliver a high-energy electric shock to the heart of a person in cardiac arrest, the implantable cardioverter defibrillator (ICD) is an internal device. Similar to an emergency defibrillator, ICDs are designed to stop dangerous heart rhythms. Instead of relying on an external machine, it is surgically placed inside the patient’s chest.

About the size of a matchbox, ICDs are implanted in patients with arrhythmias that put them at a high risk of cardiac arrest. These are often people who have survived a cardiac arrest, fainted from arrhythmia or have ventricular tachycardia, but patients with other abnormal heart rhythms or heart conditions may also be candidates for an implantable cardioverter defibrillator. The ICD monitors the heart 24/7. If it detects an abnormal heart rhythm, it automatically transmits electrical pulses to regulate the heartbeat.

Depending on the heart condition of the patient, ICDs can be programmed for different therapies from low-energy pacing to defibrillation therapy, where a high-energy shock is delivered to restore a normal heartbeat. That is the strongest electrical therapy an ICD can perform.

Pacemakers, on the other hand, are designed to treat slow heart rhythms. Like an ICD, a pacemaker constantly monitors the heart rate. If heart rate is too slow, the pacemaker will send electrical signals to the heart to speed it up. Many pacemakers have additional sensors to monitor breathing or motion, which can also signal the pacemaker to increase the heart rate to meet exertion needs.

Whether you are a candidate for a pacemaker or an ICD, your doctor will perform a variety of tests to determine if an implantable device is right for you. The implantation surgery for both devices is quite similar, usually performed under local anesthetic and a sedative to help the patient relax during the procedure. Patients spend a few hours to a day in the hospital following surgery to ensure the device is working properly. There may be post-surgery protocols such as avoiding heavy lifting or vigorous exercise in the weeks following the implantation.

The team at Advanced Cardiovascular Specialists are North Louisiana’s leading experts in cardiovascular care. To schedule an appointment, please call our office at 318-798-9400.