If your heart isn’t beating at the right rate or rhythm, doctors have several options to help you. Pacemakers and defibrillators help pace your heartbeat when heart disease and other conditions play havoc with heart rhythms.
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Your heart signals
Normally, electrical impulses generated in your heart stimulate it to contract. This moves blood through your heart, to your lungs, allowing oxygenated blood back in, and then forcefully pumping it out to your body and brain.
If the electrical impulses are interrupted for any reason, your heart rate can go too slowly and that may make a pacemaker necessary. But if the electrical impulses disorganize, your heart may go too rapidly and require an implantable defibrillator.
Cardiologist Bruce Wilkoff, MD, answers important questions about pacemakers and defibrillators (ICD).
What are pacemakers and what do they do?
Pacemakers are implantable devices that consist of:
- A battery-operated control unit (pulse generator) usually implanted under the skin in the chest area.
- Lead wire(s) that are threaded through your veins to the chambers of your heart and attached to your heart muscle to detect your heart rate and deliver small pulses of energy from the pulse generator to your heart.
Pacemakers can help:
- Prevent your heart rhythms from going too slowly.
- Coordinate your heart beats so that the top and bottom and left and right chambers beat synchronously. This may help you if you have advanced heart failure.
Dr. Wilkoff says, “Pacemakers are designed to keep your heart from going too slowly and this helps your heart to pump more blood to your body. Defibrillators rescue the heart from a rapid and confused heart rhythm which is usually fatal. Some people need help with both problems.”
What are the different types of pacemakers and different numbers of lead wires?
There are four basic kinds of pacemakers:
- Single chamber. One lead attaches to the upper (atrial) or lower (ventricular) heart chamber. Used in specific rhythm disorders.
- Dual chamber. Two leads are used, one for the upper and one for the lower chamber.
- Biventricular pacemakers (used in cardiac resynchronization therapy). These use leads attached to three places – the top chamber, and both lower chambers (right and left ventricles).
- Leadless pacemakers are a new technology that is miniaturized and positions in the lower chamber and treats slow heart rhythms without a lead.
What is a defibrillator and what does it do?
Implantable cardioverter defibrillators (ICDs) are devices that send a strong “reset” signal to your heart when the bottom chambers of your heart (ventricles) are beating very fast or erratically. These ventricular arrhythmias can occur without warning and are often fatal.
Almost 95% of all people who experience cardiac arrest die before ever reaching a hospital. Defibrillators can help:
- Save the lives of patients who have fast ventricular arrhythmias.
- Patients who have significant damage to their hearts after heart attacks or poor heart muscle function due to cardiomyopathy. These patients are at greater risk for dangerous ventricular arrhythmias and benefit from ICD implantation.
Do some patients need both a defibrillator and a pacemaker?
Yes. But most defibrillators also have pacemaker abilities. If you have heart failure, a combination biventricular-defibrillator device helps your heart to pump blood more forcefully. It also protects you against potentially fatal arrhythmias.
For others, the defibrillator protects against life threatening arrhythmias and the pacemaker backs up your heart rate if it gets too slow. Often the defibrillator can also use the pacemaker to slow down the fast heart rhythms.
There is a newer defibrillator where the lead is placed under your skin instead of through your veins. This type doesn’t pace but is better under some conditions that your doctor can explain, says Dr. Wilkoff.
Aren’t pacemakers and defibrillators just for old people?
No. Dangerous rhythm disorders can affect young people too. When athletes collapse on the field after practice, the culprit often is some form of heart rhythm abnormality.
In both cases, the defibrillator can detect when your heart starts to quiver or beat erratically and reset it, saving your life.
In order to determine what type of device is appropriate for you, your cardiologist will order tests to determine what type of rhythm disorder you have and if you need treatment.