In some people, arrhythmia are associated with heart disease. In these cases, heart disease, not the arrhythmia, poses the greatest risk to the patient.
In a very small number of people with serious symptoms, arrhythmia themselves are dangerous. These arrhythmias require medical treatment to keep the heartbeat regular. For example, a few people have a very slow heartbeat (bradycardia), Causing them to feel lightheaded or faint. If left untreated, the heart may stop beating and these people could die.
You should not panic if you experience a few flutters or your heart races occasionally. But if you have questions about your heart rhythm or symptoms, check with your doctor.
Originating in the Atria Sinus arrhythmia. Cyclic changes in the heart rate during breathing. Common in children and often found in adults. Sinus tachycardia. The sinus node sends out electrical signal faster than usual, speeding up the heart rate. Sick sinus syndrome. The sinus node does not fire its signals properly, so that the heart rate slows down. Sometimes the rate changes back and forth between a slow (bradycardia) and fast (tachycardia) rate. Premature supraventricular contractions or premature atrial contraction (PAC). A beat occurs early in the atria, causing the heart to beat before the next regular heartbeat. Supraventricular tachycardia (SVT), paroxysmal atrial tachycardia (PAT). A series of early beats in the atria speed up the heart rate ( the number of times a heart beats per minutes). In paroxysmal tachycardia, repeated periods of very fast heartbeats begin and end suddenly. Atrial flutter. Rapidly fired signals cause the muscles in the atria to contract quickly, leading to a very fast, steady heartbeat. Atrial fibrillation. Electrical signals in the atria are fired in a very fast and uncontrolled manner. Electrical signals arrive in the ventricles in a completely irregular fashion, so the heart beat is completely irregular. Wolff-Parkinson-White syndrome. Abnormal pathways between the atria and ventricles cause the electrical signal to arrive at the ventricles too soon and to be transmitted back into the atria. Very fast heart rates may develop as the electrical signal ricochets between the atria and ventricles.
Premature ventricular complexes (PVC). An electrical signal from the ventricles causes an early heart beat that generally goes unnoticed. The heart then seems to pause until the next beat of the ventricle occurs in a regular fashion. Ventricular tachycardia. The heart beats fast due to electrical signals arising from the ventricles (rather than from the atria) Ventricular fibrillation. Electrical signals in the ventricles are fired in a very fast and uncontrolled manner, causing the heart to quiver rather than beat and pump blood.
The heart is a muscular pump divided into four chamber--two atria located on the top and two ventricles located on the bottom.
Normally each heartbeat starts in the right atrium. Here, a specialized group of cells called the sinus node, or natural pacemaker, sends an electrical signal. The signal spreads throughout the atria to the area between the atria called the atrioventricular (AV) node.
The AV node connects to a group of special pathways that conduct the signal to the ventricles below. As the signal travels through the heart, the heart contracts. First the atria contract, pumping blood into the ventricles. A fraction of a second later, the ventricles contract, the ventricles contract, sending blood throughout the body.
Usually the whole heart contracts between 60 and 100 times per minute. Each contraction equals one heartbeat.
An arrhythmia may occur for one of several reasons:
Arrhythmia arising in the atria are called atria or supraventricular (above the ventricles) arrhythmias. Ventricular arrhythmias begin in the ventricles. In general, ventricular arrhythmias caused by heart disease are the most serious.
An arrhythmia may not occur at the time of the exam even though symptoms are present at other times. In such cases, tests will be done if necessary to find out whether an arrhythmia is causing the symptoms.
Serious arrhythmias are treated in several ways depending on what is causing the arrhythmia. Sometimes the heart disease is treated using one or more of the following treatments.
There are several kinds of drugs used to treat arrhythmias. One or more drugs may be used.
Drugs are carefully chosen because they can cause side effects. In some cases, they cause arrhythmias or make arrhythmias worse. For this reason, the benefits of the drug are carefully weighed against any risks associated with taking it. It is important not to change the dose or type of your medication unless you check with your doctor first.
If you are taking drugs for an arrhythmia, one of the following , one of the following tests will probably be used to see whether treatment is working: a 24-hour electrocardiogram (ECG) while you are on drug therapy, an exercise ECG, or a special technique to see how easily the arrhythmia drugs may also be checked.
To quickly restore a heart to its normal rhythm, the doctor may apply an electrical shock to the chest wall. Called cardioversion, this treatment is most used in emergency situations. After cardioversion, drugs are usually prescribed to prevent the arrhythmia from recurring.
These devices are used to correct serious ventricular arrhythmia that can lead to sudden death. The defibrillator is surgically placed inside the patient's chest. There, it monitors the heart's rhythm and quickly identifies serious arrhythmia. With an electrical shock, it immediately disrupts a deadly arrhythmia.
An artificial pacemaker can take charge of sending electrical signals to make the heart beat if the heart's natural pacemaker is not working properly or its electrical pathway is blocked. During a simple operation, this electrical device is placed under the skin. A lead extends from the device to the right side of the heart, where it is permanently anchored.
When an arrhythmia cannot be controlled by other treatment, doctors may perform surgery. After locating the heart tissue that is causing the arrhythmia, the tissue is altered or removed so that it will not produce the arrhythmia.
The National Heart, Lung, and Blood Institute also has publications about heart disease. For more information, contact:
NHLBI Communications and Public Information Branch, Building 31, Room 4A21, Bethesda, Maryland 20892.
NIH Publication No. 91-2264 April 1991 U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES Public Health Service National Institutes of Health National Heart, Lung, and Blood Institute