What is an arrhythmia?
An arrhythmia is an irregularity in the heartbeat. The heart may seem to skip a beat, beat irregularly or beat very fast or slow. There are many different types of arrhythmias. Those that arise in the upper two chambers of the heart (the atria) are known as atrial or supraventricular arrhythmias. Those arising in the ventricles (the two chambers beneath the atria) are known as ventricular arrhythmias. These are usually the most serious.
Arrhythmias themselves are dangerous in only a small number of people. For most people, the arrhythmia is not caused by heart disease but by other factors, which are often temporary. Arrhythmias occur most often in people of middle age, and increasingly in older people. For most people arrhythmias are not a serious problem and do not require special treatment.
What are the symptoms of arrhythmia?
The heart normally contracts between 60 and 100 times per minute. If there are problems with the heart, a slower heart rate may be experienced. This is called bradycardia and can cause fainting spells, light-headedness, dizziness, and fatigue. A rapid heartbeat is known as tachycardia and produces similar symptoms, including light-headedness, fainting, and dizziness. In addition, an affected person may experience palpitations (a fluttering sensation in the chest) and the heartbeat may be irregular and fast. Ventricular tachycardia can be life-threatening if the ventricles are beating so fast that the heart cannot pump sufficient blood to the vital organs. Fainting and death can follow if this condition is not treated immediately. Prolonged cases of atrial fibrillation, where the atria are quivering instead of contracting properly, can cause a stroke.
What are the causes of arrhythmia?
Normally, a heartbeat is initiated by the the sinus node, the pacemaker of the heart. However, almost any part of the heart is also capable of starting a heartbeat. If the pacemaker develops an abnormal rhythm or if another part of the heart starts a heartbeat, an arrhythmia will occur. Arrhythmias may be caused by various types of heart disease including a problem with the sinus node; heart block, where electrical signals are unable to pass through the heart normally; or extra beats starting in the atria or ventricles. In many people, the cause of the arrhythmia is not serious. It may be caused by caffeine (eg, in coffee or cola), alcohol or tobacco. Other causes may include some appetite-suppressant drugs, some cough and cold medicines, recreational drugs, and stress. In these people, symptoms will disappear if the triggering factor is removed. Sinus arrhythmia is a very common arrhythmia that occurs when a breath is taken. It is common in children but is also found in adults and is quite normal.