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Palpitations

Palpitations Overview

The heart is a two stage electrical pump. The upper chambers of the heart, the atria, (single=atrium) collect blood from the body and pump it into the lower chambers, or ventricles. There is a little delay for the ventricles to fill, and then they pump the blood back to the body.  For this to happen in a coordinated fashion, the heart has its own electrical system

Specialized electrical cells imbedded into part of the muscles in the atrium generate the electricity and act as a pacemaker for the heart. About 60-80 times a minute; this pacemaker (the sinoatrial or SA node) fires and sends electrical signals to all of the atrial muscle cells allowing them to fire at once, generating the first half of a heart beat. Electricity also travels to the ventricles but is held up for a split second in the junction between the atrium and ventricle at the atrio-ventricular node to allow the ventricles to fill with blood. Then the signal travels through electrical bundles to allow all the muscle cells of the ventricles to fire at once, causing the second half of the heart beat, and pumping blood to the body. There is then another split second when the electrical system resets itself to get ready for the next electrical impulse and heart beat.

Palpitations occur when a person can feel abnormalities in the normal beating of the heart. These palpitations can be an isolated extra beat, or they can run together and last for prolonged periods of time. Each part of the heart has the potential to be irritable and cause an extra beat to occur. As well, short circuits in the electrical conduction system of the heart can cause "runs" of abnormal firing.

Every muscle cell in the heart has the potential to generate an electrical signal that can spread outside the normal electrical pathways and bundles to try to generate a heart beat. If the SA node fails, then other cells in the atrium try to take over. If they fail, then the AV node can take over but at a lower rate of about 40 beats per minute. And as the final backup, the ventricle itself can generate electricity but at a much slower rate of about 20 beats per minute.



Next: Types of Palpitations »

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Palpitations

Fainting Overview

Fainting, which medical professionals call syncope (pronounced SIN-ko-pea), is a temporary loss of consciousness. Unlike a seizure, the person who faints usually regains alertness soon after regaining consciousness. Fainting is caused by a temporary loss of the brain’s blood supply. Fainting can sometimes be a sign of a more serious condition.

People of any age can faint, but elderly persons more often have a serious underlying cause.

  • Three percent of adults aged 30-62 years have an episode of syncope, but 6% of those older than 75 years faint.

  • Syncope accounts for 1-3% of emergency department visits and 1-6% of hospital admissions.

  • The biggest risk is in people with heart disease, especially those with congestive heart failure or coronary heart disease.

Fainting Causes

Fainting has many different causes.

Vasovagal syncope: Also...

Read the Fainting article »



Read What Your Physician is Reading on eMedicine

Atrial Tachycardia »

Atrial tachycardia is a rhythm disturbance that arises in the atria.

Read More on eMedicine »

Medical Dictionary