Different Types of Arrhythmias-2

What are the different types of arrhythmias?

• Atrial fibrillation.

Electrical signals in the atria are fired in a very fast and uncontrolled manner. Atrial signals are rapid and chaotic beating upto 400 beats per minute. Instead of a single electrical signal followed by coordinated atrial contraction there is quivering of the atrial muscle. Not all signals are conducted through the AV node. Heart rates may vary from 100 to 180. Irregular beats (unevenly spaced) heart beats always occur with atrial fibrillation. (Heart beats are very fast but regular in PSVT). Atrial fibrillation can occur in a sustained manner or may occur episodically.


The atria do not effectively pump blood. Because most of the blood filling the ventricles does not require atrial pumping (blood flows passively into the ventricles from the atria during the heart's rest cycle) most people still have enough blood flow to the body's organs. Atrial fibrillation is usually due to atrial dilatation and associated with four conditions:

• overactive thyroid (Hyperthyroidism)
• rheumatic heart disease
• prolonged high blood pressure
• ischemic heart disease (coronary artery disease)
• It may infrequently occur in young to middle aged healthy people.

It is important for your doctor to know is you have atrial fibrillation because of increased risk of stroke. Small emboli (blood clots) are more likely to form in the atria because blood does not move as well. When these emboli break loose they may travel to the brain or other organs.

Originating in the Ventricles

• Premature ventricular complexes (PVC) an electrical signal from the ventricles causes an early heart beat that generally goes unnoticed. The heart then seems to pause until the next beat of the ventricle occurs in a regular fashion. Premature beats are common in healthy people of all ages- most people have them at some time. Usually no special treatment is needed and no cause can be found. The premature beats may disappear, and even if they continue, most people tolerate them well. Occasionally PVC's may be caused by disease or injury to the heart.

• Ventricular tachycardia (VT) .

The heart beats fast due to electrical signals arising the ventricles (rather than from the atria). It's a potentially serious condition that could threaten a person's life. Heart rate ranges from 150 to 200 beats per minute. Certain medications can make this condition worse.

VT almost always results from serious heart disease such as coronary artery disease and acute heart attacks; it usually requires prompt treatment. Ventricular tachycardia, rare in children, occurs more frequently as people age. Often specialized tests, including an intracardiac electrophysiologic procedure (see Special Tests), may be needed to evaluate the tachycardia and the effect of drug treatment. Some forms of VT may not need treatment.

• Ventricular fibrillation.

Electrical signals in the ventricles are fired in a very fast and uncontrolled manner, causing the heart to quiver rather than beat and pump blood. This is the rhythm responsible for "shocking" unconscious people on television shows. The ventricle "quivers" with no effective pumping of blood. The heart has not actually stopped. Because the heart does not pump blood to the body a person in ventricular fibrillation loses consciousness immediately.

VF is almost always seen in patients with severe coronary artery disease. Much less commonly it may occur in younger people with normal coronary arteries who have certain inherited heart conditions and in people who have had the heart muscle or conduction system injured by infection (myocarditis). VF may also occur with a very hard blow to the chest, abnormal concentrations of certain minerals in the body, too low a body temperature (hypothermia), and when the amount of certain medications in the body is too high.

Electrical cardioversion, using DC current, is always the first treatment. With an electrical shock, it immediately disrupts a deadly arrhythmia. To have any chance of recovery cardioversion must be done quickly. CPR is started if cardioversion unsuccessful after 3 consecutive attempts.

Cardiac Standstill (Asystole)

Is the complete absence of heart electrical activity. This is often a terminal arrhythmia usually causing death. That is other arrhythmias, such as ventricular fibrillation, progress to asystole if not treated. The heart does not pump or even quiver.