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What is arrhythmia?
An arrhythmia is a problem with the rate or rhythm of the heartbeat. It may involve the heart beating too fast, too slow or with another form of irregularity.
When the heart beats too fast, it is called tachycardia. A slow heartbeat is called bradycardia.
Some arrhythmias can be serious or life-threatening, but most are harmless. The heart may have problems pumping blood to the rest of the body during an arrhythmia. When this occurs, lack of blood flow can cause damage to the brain, heart or other organs.
When the heart beats, an electrical signal begins in the sinus node or sinoatrial node, which is located in the upper right chamber of the heart, or the right atrium. The signal passes through pathways in the right and left atria before moving down through other pathways of the left bundle branch and right bundle branch to the two lower chambers, the right and left ventricle. The heart contracts and pumps blood as this electrical signal moves. The ventricles then relax, and the process begins again in the sinoatrial node. This occurs between 60 and 100 times per minute in most healthy adults.
An arrhythmia can occur in any part of this process.
The most common type of arrhythmia is atrial fibrillation. Other types include atrial flutter, bradyarrhythmias, paroxysmal supraventricular tachycardia, premature (extra) beats, supraventricular arrhythmias and ventricular arrhythmias.
A prior heart attack, heart failure or cardiomyopathy, congenital heart defects, high blood pressure, diabetes, sleep apnea, smoking, stress or other unhealthy behaviors may cause an arrhythmia. Age is also a risk factor, as arrhythmias are common in older adults.
Symptoms include a slow or irregular heartbeat, heart palpitations or the feeling of pauses between heartbeats. More serious symptoms include anxiety, chest pain, dizziness, fainting, light-headedness, shortness of breath, fainting and sweating.
Additional information about arrhythmia may be found at these websites:
http://www.nlm.nih.gov/medlineplus/arrhythmia.html
http://www.nhlbi.nih.gov/health/health-topics/topics/arr/
http://www.escardio.org/Pages/index.aspx
http://www.cardiosource.org/acc
http://www.cardiosmart.org/cardiosmart/default.aspx?id=192
http://content.onlinejacc.org/
http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0004449/