Introduction to Arrhythmia
An irregular heartbeat is an arrhythmia (also called dysrhythmia). Heart rates can also be irregular. A normal heart rate is 50 to 100 beats per minute. Arrhythmias and abnormal heart rates don't necessarily occur together. Arrhythmias can occur with a normal heart rate, or with heart rates that are slow (called bradyarrhythmias -- less than 50 beats per minute). Arrhythmias can also occur with rapid heart rates (called tachyarrhythmias -- faster than 100 beats per minute). In the United States, more than 850,000 people are hospitalized for an arrhythmia each year.
What causes an arrhythmia?
Arrhythmias may be caused by many different factors, including:
- Coronary artery disease.
- Electrolyte imbalances in your blood (such as sodium or potassium).
- Changes in your heart muscle.
- Injury from a heart attack.
- Healing process after heart surgery.
- Irregular heart rhythms can also occur in "normal, healthy" hearts.
What are the types of arrhythmias?
The types of arrhythmias include:
- Premature atrial contractions. These are early extra beats that originate in the atria (upper chambers of the heart). They are harmless and do not require treatment.
- Premature ventricular contractions(PVCs). These are among the most common arrhythmias and occur in people with and without heart disease. This is the skipped heartbeat we all occasionally experience. In some people, it can be related to stress, too much caffeine or nicotine, or too much exercise. But sometimes, PVCs can be caused by heart disease or electrolyte imbalance. People who have a lot of PVCs, and/or symptoms associated with them, should be evaluated by a heart doctor. However, in most people, PVCs are usually harmless and rarely need treatment.
- Atrial fibrillation. Atrial fibrillation is a very common irregular heart rhythm that causes the atria, the upper chambers of the heart, to contract abnormally.
- Atrial flutter. This is an arrhythmia caused by one or more rapid circuits in the atrium. Atrial flutter is usually more organized and regular than atrial fibrillation. This arrhythmia occurs most often in people with heart disease and in the first week after heart surgery. It often converts to atrial fibrillation.
- Paroxysmal supraventricular tachycardia (PSVT). A rapid heart rate, usually with a regular rhythm, originating from above the ventricles. PSVT begins and ends suddenly. There are two main types: accessory path tachycardias and AV nodal reentrant tachycardias (see below).
- Accessory pathway tachycardias. A rapid heart rate due to an extra abnormal pathway or connection between the atria and the ventricles. The impulses travel through the extra pathways as well as through the usual route. This allows the impulses to travel around the heart very quickly, causing the heart to beat unusually fast.
- AV nodal reentrant tachycardia. A rapid heart rate due to more than one pathway through the AV node. It can cause heart palpitations, fainting, or heart failure. In many cases, it can be terminated using a simple maneuvers, such as breathing in and bearing down, and others performed by a trained medical professional. Some drugs can also stop this heart rhythm.
- Ventricular tachycardia (V-tach). A rapid heart rhythm originating from the lower chambers (or ventricles) of the heart. The rapid rate prevents the heart from filling adequately with blood; therefore, less blood is able to pump through the body. This can be a serious arrhythmia, especially in people with heart disease, and may be associated with more symptoms. A heart doctor should evaluate this arrhythmia.
- Ventricular fibrillation. An erratic, disorganized firing of impulses from the ventricles. The ventricles quiver and are unable to contract or pump blood to the body. This is a medical emergency that must be treated with cardiopulmonary resuscitation (CPR) and defibrillation as soon as possible.
- Long QT syndrome. The QT interval is the area on the electrocardiogram that represents the time it takes for the heart muscle to contract and then recover, or for the electrical impulse to fire impulses and then recharge. When the QT interval is longer than normal, it increases the risk for "torsade de pointes," a life-threatening form of ventricular tachycardia. Long QT syndrome is an inherited condition that can cause sudden death in young people. It can be treated with antiarrhythmic drugs, pacemaker, electrical cardioversion, defibrillation, implanted cardioverter/defibrillator, or ablation therapy.
- Bradyarrhythmias. These are slow heart rhythms, which may arise from disease in the heart's electrical conduction system. Examples include sinus node dysfunction and heart block.
- Sinus node dysfunction. A slow heart rhythm due to an abnormal SA (sinus) node. Significant sinus node dysfunction that causes symptoms is treated with a pacemaker.
- Heart block. A delay or complete block of the electrical impulse as it travels from the sinus node to the ventricles. The level of the block or delay may occur in the AV node or HIS-Purkinje system. The heart may beat irregularly and, often, more slowly. If serious, heart block is treated with a pacemaker.
Atrial Fibrillation (AFIB) Symptoms
What are the symptoms of atrial fibrillation?
The most common symptom of atrial fibrillation is palpitations, an uncomfortable awareness of the rapid and irregular heartbeat. Other symptoms of atrial fibrillation are caused by the diminished delivery of blood to the body. These symptoms include:
- shortness of breath, and
- angina (chest pain due to reduced blood flow to the heart muscles).
What are the symptoms of arrhythmias?
An arrhythmia can be silent and not cause any symptoms. A doctor can detect an irregular heartbeat during a physical exam by taking your pulse or through an electrocardiogram (ECG).
When symptoms of an arrhythmia occur, they may include:
How are arrhythmias diagnosed?
Tests used to diagnose an arrhythmia or determine its cause include:
How are arrhythmias treated?
Treatment depends on the type and seriousness of your arrhythmia. Some people with arrhythmias require no treatment. For others, treatments can include medication, making lifestyle changes, and undergoing surgical procedures.
What Drugs Are Used to Treat Arrhythmias?
A variety of drugs are available to treat arrhythmias. These include:
- Antiarrhythmic drugs. These drugs control heart rate and include beta-blockers.
- Anticoagulant or antiplatelet therapy. These drugs reduce the risk of blood clots and stroke. These include warfarin (a "blood thinner") or aspirin. Another blood thinner called Pradaxa (dabigatran) was approved in 2010 to prevent stroke in people with atrial fibrillation.
Because everyone is different, it may take trials of several medications and doses to find the one that works best for you.
Lifestyle Changes Can Help Arrhythmias?
- If you notice that your arrhythmia occurs more often with certain activities, you should avoid them.
- If you smoke, stop.
- Limit your intake of alcohol.
- Limit or stop using caffeine. Some people are sensitive to caffeine and may notice more symptoms when using caffeine products (such as tea, coffee, soft drinks, and some over-the-counter medications).
- Stay away from stimulants used in cough and cold medications. Some such medications contain ingredients that promote irregular heart rhythms. Read the label and ask your doctor or pharmacist what medication would be best for you.
What Is Electrical Cardioversion?
If drugs are not able to control a persistent irregular heart rhythm (such as atrial fibrillation), cardioversion may be required. After administration of a short-acting anesthesia, an electrical shock is delivered to your chest wall that synchronizes the heart and allows the normal rhythm to restart.
What is a pacemaker?
A pacemaker is a device that sends small electrical impulses to the heart muscle to maintain a suitable heart rate. Pacemakers primarily prevent the heart from beating too slowly. The pacemaker has a pulse generator (which houses the battery and a tiny computer) and leads (wires) that send impulses from the pulse generator to the heart muscle. Newer pacemakers have many sophisticated features that are designed to help manage arrhythmias and optimize heart rate-related function as much as possible.
What is an implantable cardioverter-defibrillator (ICD)?
An ICD is a sophisticated device used primarily to treat ventricular tachycardia and ventricular fibrillation, two life-threatening heart rhythms. The ICD constantly monitors the heart rhythm. When it detects a very fast, abnormal heart rhythm, it delivers energy to the heart muscle to cause the heart to beat in a normal rhythm again. There are several ways the ICD can be used to restore normal heart rhythm. They include:
- Anti-tachycardia pacing (ATP). When the heart beats too fast, a series of small electrical impulses may be delivered to the heart muscle to restore a normal heart rate and rhythm.
- Cardioversion. A low energy shock may be delivered at the same time as the heart beats to restore normal heart rhythm.
- Defibrillation. When the heart is beating dangerously fast or irregularly, a higher energy shock may be delivered to the heart muscle to restore a normal rhythm.
- Anti-bradycardia pacing. Many ICDs provide back-up pacing to maintain heart rhythm if it slows too much.
What Is Catheter Ablation?
During an ablation, high-frequency electrical energy is delivered through a catheter to a small area of tissue inside the heart that causes the abnormal heart rhythm. This energy "disconnects" the pathway of the abnormal rhythm. Ablation is used to treat most PSVTs, atrial flutter, atrial fibrillation, and some atrial and ventricular tachycardias. Ablation may be combined with other procedures to achieve optimal treatment.
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What Is Heart Surgery?
Heart surgery may be needed to correct heart disease that may be causing the arrhythmia. The Maze procedure is a type of surgery used to correct atrial fibrillation. During this procedure, a series (or "maze") of incisions are made in the right and left atria to confine the electrical impulses to defined pathways. Some people may require a pacemaker after this procedure.
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