Recent Blog Articles
5 inflammation-fighting food swaps
Is IBD an underrecognized health problem in minority groups?
Sickle cell disease in newborns and children: What families should know and do
COVID-19 vaccines for children and teens: What we do — and don’t — know
Happy trails: Take a hike, now
Sleep well — and reduce your risk of dementia and death
COVID-19 vaccines and the LGBTQ+ community
Polycystic ovary syndrome and the skin
Dental appliances for sleep apnea: Do they work?
Terrified of needles? That can affect your health
Implantable Cardioverter Defibrillator (ICD)
What Is It?
An implantable cardioverter defibrillator (ICD) is a potentially lifesaving medical device that is placed inside the body. An ICD treats life-threatening abnormal heart rhythms (called arrhythmias), including ventricular fibrillation, which makes the heart's large muscular chambers (the ventricles) quiver without actually squeezing and pumping. When this happens, there is no real heartbeat and not enough blood flows to the brain or other organs, including the heart. As a result, a person with ventricular fibrillation passes out and can die within minutes.
An ICD is made of two parts. The pulse generator looks like a small box. It is implanted under the skin below the collarbone. The box contains a lithium oxide battery (which lasts about five to nine years) and electrical components that analyze the heart's electrical activity. Connected to the pulse generator are one or more electrodes, which travel to the heart. When the ICD senses an abnormal heart rhythm, it administers a brief, intense electrical shock to the heart, correcting the abnormal rhythm. Many people say that the shock feels like being punched in the chest, although the amount of discomfort varies.
To continue reading this article, you must log in.
Subscribe to Harvard Health Online for immediate access to health news and information from Harvard Medical School.
- Research health conditions
- Check your symptoms
- Prepare for a doctor's visit or test
- Find the best treatments and procedures for you
- Explore options for better nutrition and exercise
I'd like to receive access to Harvard Health Online for only $4.99 a month.Sign Me Up
Already a member? Login ».
As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review or update on all articles. No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.