MedicineNet.com
MedicineNet home Picture Slideshows Diseases and conditions Symptoms and signs Procedures and tests Medications Health and Living Health news and views MedTerms medical dictionary
Font Size
A
A
A


Premature Ventricular Contractions
(PVCs)

Medical Author: Dennis Lee, MD
Medical Editor: William C. Shiel, Jr, MD, FACP, FACR

What are premature ventricular contractions?

Premature ventricular contractions (PVCs) are premature heartbeats originating from the ventricles of the heart. PVCs are premature because they occur before the regular heartbeat.

Normal function of the heart

The heart has four chambers. The upper two chambers are the atria, and the lower two chambers are the ventricles. The atria deliver blood to the ventricles, and the ventricles deliver blood to the lungs and to the rest of the body. (The right ventricle delivers blood to the lungs while the left ventricle delivers blood to the rest of the body). The heartbeat (pulse) that we feel is caused by the contraction of the ventricles.

The heartbeat is normally controlled by the electrical system of the heart. The electrical system of the heart consists of the SA node (sino-atrial node), the AV node (atrio-ventricular node) and special tissues in the ventricles that conduct electricity.

The SA node is the heart's electrical pacemaker. It is a small patch of cells located in the wall of the right atrium; the frequency with which the SA node discharges electricity determines the rate at which the heart normally beats. The SA node keeps the heart beating in a regular manner. At rest, the frequency of the electrical discharges originating from the SA node is low, and the heart beats at the lower range of normal (60-80 beats/minute). During exercise or excitement, the frequency of discharges from the SA node increases, increasing the rate at which the heart beats.

The electrical discharges pass from the SA node, through the special tissues of the atria into the AV node, and through the AV node to the special conduction tissues of the ventricles and causing the ventricles to contract.

What happens during a premature ventricular contraction?

During a premature ventricular contraction, the ventricle electrically discharges (and contracts) prematurely before the normal electrical discharges arrive from the SA node. These premature discharges are due to electrical "irritability" of the heart muscle of the ventricles, and can be caused by heart attacks, electrolyte imbalances, lack of oxygen, or medications. Immediately after a premature ventricular contraction, the electrical system of the heart resets. This resetting cause a brief pause in heartbeat, and some patients report feeling the heart briefly stopping after a premature ventricular contraction.



Next: How common are premature ventricular contractions? »

Premature Ventricular Contractions - Symptoms Experienced

The MedicineNet physician editors ask:

Please describe the symptoms of your premature ventricular contractions.

Comment submissions for this question have ended. Patient Discussions FAQs
See 21 Viewer Comments

View Comments


Printer-Friendly Format  |  Email to a Friend


Suggested Reading by Our Doctors
MedicineNet Doctors
  • Beta Blockers - Learn more about Beta Blockers, a drug that treats angina and other heart rhythm disorders, migraines, high blood pressure, panic attacks, and tremors. Generic and brand names are included in the article.
  • Electrocardiogram (ECG or EKG) - Read about the Electrocardiogram (ECG, EKG) procedure used to reflect underlying heart conditions such as agnina, occurance of a prior heart attack or of an evolving heart attack, and more.
  • Palpitations - Learn about palpitations (abnormal heart beats, too fast or too slow) and what causes them, such as exessive alcohol, caffeine, stress, and more. Information includes types, causes, symptoms, and treatment options.

Latest Medical News


Heart Health

Get the latest treatment options.




Symptoms & Signs A-Z List Pinpoint Your Symptoms - Start Now Symptoms & Signs A-Z List Symptoms & Signs by Female Body Region Symptoms & Signs by Male Body Region

Topics Related to Premature Ventricular Contractions

Medications
Procedures & Tests
Diseases & Conditions

Premature Ventricular Contractions
RSS FeedSpecialty RSS       Add to My Yahoo! What is this?

At Risk for Heart Disease?At Risk for Heart Disease?
Thanks to new technology, in just 15 seconds you can tell if you’re at risk for heart disease. Learn about this new tool. See more WebMD Videos »






Top 3
Premature Ventricular Contractions Related Articles







Health categories:

Slideshows | Diseases & Conditions | Symptoms & Signs | Procedures & Tests | Medications | Health & Living | News & Views | Medical Dictionary

Popular health centers:

Allergies | Arthritis | Cancer | Diabetes | Digestion | Healthy Kids | Heart | Men's Health | Mental Health | Women's Health | More...

Publications:

ePublications (PDFs) | XML News via RSS | Audio Podcasts | Email Newsletters

MedicineNet.com:

About Us | Privacy Policy | Search Help | Site Map | WebMD® | Medscape® | eMedicine® | eMedicineHealth® | RxList®

This website is certified by Health On the Net Foundation. Click to verify. This site complies to the HONcode standard for trustworthy health information:
verify here.

©1996-2009 MedicineNet, Inc. All rights reserved. Notices and Legal Disclaimer.
MedicineNet does not provide medical advice, diagnosis or treatment. See additional information.