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What Are the Different Kinds of Arrhythmias?

Bradycardia (very slow heart rate)

In bradycardia, the heart rate is less than 60 beats per minute. Symptoms for bradycardia are tiredness, shortness of breath, dizziness, or feeling faint.

Tachycardia (very fast heart rate)

In tachycardia the heart beats faster than 100 beats per minute. Symptoms for tachycardia may include a strong pulse in the neck or a fluttering, racing beat in the chest. People with tachycardia may also feel discomfort in the chest, weak, short of breath, dizzy and sweaty.

There are various forms of tachycardia, including SVTs and VTs. Examples of SVTs are atrial flutter, atrial fibrillation, AVNRT, and AVRT. SVT, which stands for supraventricular tachycardia, is a rapid heartbeat that originates in an area above the ventricles of the heart ("supra" means "above"). VTs are rapid abnormal heartbeats originating in the ventricles (the lower chambers of the heart).

In some patients, in addition to the AV node, there is an extra electrical connection between the atria and the ventricles. This abnormal connection is called an accessory pathway or bypass tract, and can cause a particular tachycardia known as AV Reentry Tachycardia (AVRT). In patients with an extra conduction pathway, the electrical signal may arrive at the ventricles too soon, causing a rapid heartbeat. This tachycardia is known as Wolff-Parkinson-White syndrome (WPW), a form of AVRT.

AVNRT (which stands for atrioventricular nodal reentrant tachycardia) occurs because there are two anatomically and physiologically distinct pathways (fast and slow pathways) that join at and with the AV node. These two pathways can form a small "loop circuit" that results in AVNRT in some people. The AV node is a secondary node in the heart that sends electrical impulses from the sinoatrial node and atria to the lower chambers of the heart, the ventricles.

Atrial flutter is an arrhythmia that can occur in either the left or right atrium, but more commonly the right. Atrial flutter is a rapid, regular rhythm, resulting in fast atrial and ventricular rates. As a result, the atria are compromised in their ability to empty blood flow into the ventricles.

Another form of tachycardia which affects the atria is atrial fibrillation; this is a very common arrhythmia and is characterized by fast and uncoordinated beats of the atria, caused by the random contraction of individual heart-muscle fibers.

Irregular heart beat

Some arrhythmias are characterized by chaotic heartbeats. The most serious form of irregular heart rhythm is ventricular fibrillation, in which several impulses that begin at the same time from different locations all tell the heart to beat. The result is a much faster, uncontrolled heart rhythm that may reach 300 beats a minute. As a consequence of this chaotic heartbeat, very little blood may be pumped from the heart to the brain and body, and may result in fainting. This condition requires immediate attention from a physician.

Symptoms of arrhythmia are due mostly to how fast the ventricle is beating (your pulse). The faster the pulse, the more severe the symptoms. The presence of other types of heart disease may also affect symptoms.