Ventricular & Supraventricular




If you or a family member are suffering from palpitations
or fainting (synscope), you should be seen
by a cardiologist.

The following are lower chamber (ventricles) arrhythmias:

Ventricular Tachycardia - VT:
V-tach is a rapid heart beat (160 -240 bpm) that originates in the one of the lower chambers (ventricles of the heart.) The heart muscle is not beating normally--the heartbeat will quicken and you feel as if your heart is "skipping beats." This rhythm may cause severe shortness of breath, dizziness, or fainting (synscope). VT that lasts longer than 30 seconds is referred to as sustained ventricular tachycardia. Any episode of VT that causes symptoms needs to be treated. An episode that lasts more than 30 seconds, even without symptoms, also needs to be treataed. Drug therapy can be give intravenously to suppress episodes of V-tach or if blood pressure falls below normal, a person will need electric cardioversion (sock) immediately. (Gale Encyclopedia of Medicine)

Ventricular Fibrillation - VF:
This is the most serious arrhythmia--it is uncontrolled, chaotic and can reach 300 bpm. Medical attention is needed right away--CPR can be started, or electrical energy is used to defibrillate or "shock" the heart back to a normal rhythm. Ventricular fibrillation is often associated with acute ischemic events (ischemia involves the deprivation of oxygenated blood to an area of tissue), and with chronic ischemic heart disease. It is frequently seen immediately following a heart attack. It may also develop during hypoxia, atrial fibrillation, or improper grounding of electrical devices. An extremely low level of potassium in the blood can also cause ventricular fibrillation. (Gale Encyclopedia of Medicine)

Premature Ventricular Contractions - PVCs:
PVCs are a fairly common type of irregular heart rhythm (arrhythmia). In the normal sequence of events, a heartbeat is initiated in the top right chamber of the heart (right atrium) and subsequently
conducted to the bottom chambers of the heart (ventricles). A premature ventricular contraction occurs when the ventricles fire early (prematurely), before the atria. PVCs are less serious and usually do not need treatment. They are disconcerting, however, and they can happen in response to caffeine--coffee, tea, sodas and chocolate and some kinds of over-the-counter cough or cold medicines and alcohol.

Some people may feel skipped beats or galloping palpitations, and other people may not notice PVCs at all. In general, these irregular beats are harmless. However, diagnosing them and ruling out heart disease may be important. People are also urged to contact their physician if they experience chest pain
or a sudden worsening of their PVCs. If necessary, treatment generally involves taking medication, such as beta blockers or antiarrhythmics.

The following are supraventricular, or upper chamber (atria) arrhythmias:

Supraventricular Tachycardia - SVT:
A rapid, regular heart rate where the heart beats more than 150 bpm. The abnormal electrical impulses may start in the SA node, the atria, orthe AV node. The heart beats so fast that the heart muscle cannot relax between contractions and it does not receive adequaate blood for pumping. You brain receives reduced amounts of blood or oxygen. You can become lightheaded, dizzy or feel like fainting. Most people who experience it live a healthy life w/o restrictions.

In some cases, simply maneuvers, called vagal may assist your body in slow your heart rate: (1) Hold your breath for a few seconds... (2) dip your face in cold water... (3) cough... (4) Tense your stomach muscles as if you are bearing down to have a bowel movement. (

Atrial Fibrillation - A-fib:
Please See the Site Index for a complete section on Atrial Fibrillation.

A fast irregular rhythm--it can be a cause of stroke because of blood that pools in the heart's upper chambers.

Wolff-Parkinson-White Syndrome:
WPW syndrome is a very fast heart rate caused by a group of abnormalities--extra muscle pathways between the atria and the ventricles.

Atrial Flutter:
This happens when the atria beat very fast, causing the ventricles to beat inefficiently as well.

(This article was also written with assistance of the Merck Manual.)

For information on the Symptoms, Diagnosis and Treament of Arrhythmias, please click here.

For information on Heart Block, Long QT Syndrome & Torsades des Pointes, click here.


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Last Modified on September 21, 2002

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