Arrhythmia
Overview:
Quick Reference
Reviewed by Dr. James WhynotAn interruption in the normal beating rhythm of the heart is called an arrhythmia, or irregular heartbeat. Almost everyone experiences arrhythmia in the form of a mild palpitation or a skipped heartbeat at some point in his or her life. Arrhythmias are common, especially as you get older, and they affect millions of people. Isolated incidences are usually innocuous, but a physician should look at a recurrent arrhythmia or arrhythmias accompanied by symptoms listed below.
Detailed Information
Many types of heart disease cause arrhythmia. Coronary artery disease, which can cause a heart attack, produces scar tissue that can disrupt the transmission of electrical signals. Other causes of arrhythmia include congenital heart disease, heart valve disorders, lung disease (smoking, congenital and acquired)and thyroid conditions (both over active and under active thyroid). There are many types of arrhythmia: the most common ones are tachycardia, bradycardia and an irregular heartbeat. Tachycardia is too fast a heartbeat (more than 100 beats per minute), and bradycardia is too slow a heartbeat (less than 60 beats per minute). An irregular heartbeat occurs when one can feel the skipped beats. Normally, the heart beats between 60 and 100 times per minute when someone is at rest.
Arrhythmias can begin in the ventricle (the pumping part of the heart) or the atria (the chamber the blood enters prior to entering the ventricle.
Most arrhythmias are of the tachycardia type (tachyarrhythmia). Tachyarrhythmia that starts in the ventricle is usually more serious than one that starts in the atria. Ventricular arrhythmias are more serious because the ventricles are reduced to twitching, and almost no pumping takes place, thus the blood cannot get to other parts of the body. Atrial tachyarrhytmias can be serious, because again, the atrial is reduced to twitching and clots may build up in the atria. If the clot breaks loose from the atria, an embolus (small clot) can be sent to various parts of the body, cutting off blood supply and can cause a stroke or loss of blood supply to fingers, hands, legs or toes.
Bradycardias (bradyarrhythmias) are sometimes caused by problems with the nerves that control the speed your heartbeat, the sinus node (which is where the electrical impulse that tells the heart to beat originates), or the transmission of those impulses through the heart. Atrial bradyarrhythmias occur when the sinus node is not functioning correctly. This can be due to trauma, aging, elevated cholesterol or other diseases that can cause problems in the conducting system of the heart.
Ventricular arrhythmias occur when the electrical conducting system (the wiring) from the sinus node to the heart does not function properly. The ventricle itself has its own intrinsic beat at about 45 beats per minute if the conducting system from the atrium fails.
Irregular heartbeats occur when there is some problem with the electrical system of the heart or when the atria send out too many signals (i.e. other parts of the atrium other than the sinus node send out a signal for the ventricles to contract).
Symptoms of tachycardia include:
- Recurrent palpitations that may feel like a strong neck pulse or a fluttering, pounding, or racing beat in the chest
- Chest discomfort
- Weakness, fainting, shortness of breath, dizziness
Symptoms of bradycardia include:
- Fatigue
- Shortness of breath
- Lightheadedness
Symptoms of an irregular heartbeat may be all of the symptoms for either tachycardia or bradycardia.
Treatment/Prevention
An ECG of the heart is the most accurate indicator of arrhythmia, if the arrhythmia occurs during testing. If the arrhythmia does not occur at the doctor’s office, patients may be sent home with a Holter monitor. This portable device can record the heart’s activity over a 24-hour period.A stress test may provoke arrhythmia, so running on a treadmill as part of one may make diagnosis easier. Echocardiogram, or ultrasound of the heart, can detect an accompanying heart muscle or valve disease.
To determine if arrhythmias are caused by coronary artery disease, a cardiac catheterization may be performed. The doctor inserts a catheter into a blood vessel and guides it to the heart via X-ray. Contrast dye is injected so that the heart can be viewed.
Treatment of arrhythmia varies from patient to patient. In some cases, no treatment is necessary. These are the so-called benign arrhythmias. Physicians usually advise: limiting your intake of caffeine, quit smoking, and limit your alcohol consumption. Relieve your stress with exercise or meditation. For people with more serious arrhythmia, your physician will discuss various treatment options.
Antiarrhythmic drugs are available, such as quinidine and admidarone. Your doctor may prescribe one for you, depending upon type of arrhythmia and medical history.
Another form of treatment is an implanted pacemaker, especially for people with bradycardia. People with ventricular tachycardias may use a cardioverter defibrillator, which provides shock therapy when needed.
Another option is catheter ablation. In this procedure, the part of the heart causing the interference is damaged to prevent it from sending electrical impulses.
In more serious cases, open-heart surgery may be necessary to treat heart valve disease that may cause arrhythmias.
In an emergency situation, arrhythmia is treated with electric shock.
To prevent further bouts of arrhythmia, limit your intake of caffeine, quit smoking, and limit your alcohol consumption. Relieve your stress with exercise or meditation.
Last updated: 04-Mar-03
