Arrhythmia

Arrhythmia

Cardiac dysrhythmia (also known as arrhythmia or irregular heartbeat) is any of a group of conditions in which the electrical activity of the heart is irregular or is faster or slower than normal. The heartbeat may be too fast (over 100 beats per minute) or too slow (less than 60 beats per minute), and may be regular or irregular. A heart beat that is too fast is called tachycardia and a heart beat that is too slow is called bradycardia. Although many arrhythmias are not life-threatening, some can cause cardiac arrest.

Arrhythmias can occur in the upper chambers of the heart (atria), or in the lower chambers of the heart (ventricles). Arrhythmias may occur at any age. Some are barely perceptible, whereas others can be more dramatic and can even lead to sudden cardiac death.

cause

• Normally, the heart's most rapidly firing cells are in the sinus (or sinoatrial or SA) node, making that area a natural pacemaker.
• Under some conditions almost all heart tissue can start an impulse of the type that can generate a heartbeat. Cells in the heart's conduction system can fire automatically and start electrical activity. This activity can interrupt the normal order of the heart's pumping activity.
• Secondary pacemakers elsewhere in the heart provide a "back-up" rhythm when the sinus node doesn't work properly or when impulses are blocked somewhere in the conduction system.

An arrhythmia occurs when:

• The heart's natural pacemaker develops an abnormal rate or rhythm.
• The normal conduction pathway is interrupted.
• Another part of the heart takes over as pacemaker.