There are many types of arrhythmia (known as irregular heartbeat or abnormal heart rhythm). Some of them may occur in the atria, while the other in the ventricles. People with arrhythmia may not develop a serious problem, but some heart arrhythmias can cause bothersome (or even life-threatening) signs and symptoms. Ventricular arrhythmias are considered more serious than atrial arrhythmias.
These are some types of arrhythmia:
- Atrial fibrillation. This is a very common type of arrhythmia that causes the atria (upper chambers of the heart from which blood is passed to the ventricles) to contract abnormally.
- Ventricular fibrillation. An uncoordinated contraction of the cardiac muscle of the ventricles (larger and lower cavities of the heart). The ventricles quiver and are unable to contract or pump blood to the body. A patient with ventricular fibrillation must be treated with cardiopulmonary resuscitation (CPR) as soon as possible. Ventricular fibrillation is the most commonly identified arrhythmia in cardiac arrest patients.
- Atrial flutter. This is an abnormal heart rhythm that occurs in the atria of the heart, and it is usually more organized and regular than atrial fibrillation. It is caused by one or more rapid circuits in the atrium. Atrial flutter often occurs in people with heart disease and in the first week after heart surgery. It often degenerates into atrial fibrillation.
- Premature atrial contractions (PACs). They occur due to the premature discharge of an electrical impulse in the atrium, causing a premature contraction. They occur earlier than the next regular beat should have occurred. PACs are harmless and generally do not require treatment.
- Premature ventricular contractions (PVCs). These are premature heartbeats originating from the ventricles of the heart. They occur before the regular heartbeat. PVCs can happen in people with or without heart disease. It can be related to stress, too much caffeine or nicotine, or too much exercise. PVCs are usually harmless and rarely need treatment. However. people who have a lot of PVCs should be evaluated by a heart doctor.
- Paroxysmal supraventricular tachycardia (PSVT). This is a rapid heart rhythm originating from above the ventricles. The rapid rate occurs sporadically and without warning. It may last a few seconds or many hours. There are two main types: accessory path tachycardias and AV nodal reentrant tachycardias (see below).
- Bradyarrhythmias (Bradycardia). These are slow heart rhythms, which may arise from disease in the heart’s electrical conduction system. In adults, it is defined as a heart rate of less than 60 beats per minute. Examples include sinus node dysfunction and heart block.
- Heart block. This is a problem in the electrical system of the heart. A delay or complete block of the electrical impulse as it travels from the sinus node to the ventricles. The heart may beat irregularly and, often, more slowly. In a serious case, heart block is treated with a pacemaker.
- Long QT syndrome. This is an inherited condition characterized by a prolongation of the QT interval on electrocardiograms (ECGs) and a propensity to ventricular tachyarrhythmias, which may lead to syncope, cardiac arrest, or sudden death. When the QT interval is longer than normal, it increases the risk of a life-threatening form of ventricular tachycardia. It can be treated with antiarrhytmic drugs, pacemaker, electrical cardioversion, defibrillation, and ablation therapy.
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