Once your doctor diagnoses an arrhythmia through your symptoms or an examination, he or she will need to determine where it originates and whether it requires treatment; that is, whether it is causing symptoms or putting you at risk for more serious problems in the future.
The electrocardiogram is a very important tool that your doctor uses to diagnose and study your arrhythmia. The ECG records and measures the path and timing of your heart’s electri- cal impulses from their origin in the sinoatrial node, through the atria, through the atrioventricular node, and into and through the ventricles. However, the standard ECG can only record the electrical activity that takes place during the short time that the machine is hooked up to you.
Ambulatory ECG methods enable your doctor to study longer periods of the heart’s activity while you go about your normal routine. Ambulatory ECGs are available in the form of a Holter monitor , which you wear for 24 to 48 hours and which provides a continuous readout. Your doctor compares the ECG recordings with your account of your activities and symptoms to see if an arrhythmia is occurring, how often it occurs, and how it relates to the daily log of your activities. Also, the effectiveness of any antiarrhythmic medica- tions you may be taking can be monitored. However, if your arrhyth- mia is very infrequent, 48 hours of Holter monitoring may not capture it.
An event monitor is another ambulatory ECG, one that allows for longer recording—as long as 30 days. You activate the device yourself if you sense symptoms. The monitor’s recording system is “looped” to continuously record and erase, so that when you activate it, it can retrieve data from 1 to 4 minutes prior to that time.
Your doctor may want to order exercise stress testing to see if an arrhythmia is brought on by exercise. If you have had faint- ing spells, you may be asked to have a tilt-table study to observe how your heart responds to a change in position. This informa- tion helps your doctor determine how to prevent fainting episodes. Echocardiography may also be used to determine if there is structural heart disease that may be causing arrhythmias.
Electrophysiologic studies are done in a hospital setting to more speci?cally study an arrhythmia, test the effect of medications, and perform some treatments such as catheter ablation. Electrophysio- logic studies are generally done by threading catheters through the veins into your heart in order to record electrical signals and stimulate the heart to induce an arrhythmia, to provide more precise information about your heart rhythms. Because the test requires that catheters are placed in your veins, it is described as an invasive study. However, with proper preparation, electrophysiology studies can be performed with little or no discomfort and are among the safest of all invasive tests. Also, impor- tantly, if possible, some arrhythmias are treated or cured at the same sit- ting during your electrophysiologic studies, with only a small risk to you.
Electrophysiology studies require taking periodic X-rays via ?uo- roscopy during the procedure to determine where the catheter is within the heart. In some cases, transesophageal echocardiography may be used.
Substances That Can Affect Heart Rhythm
Thousands of substances have the potential to affect the electrical signals that stimulate your heartbeat. The impact of any one of them on you can range from harmless to severe. If you are diagnosed with a heart arrhythmia, be aware of your own exposure to some of these substances, and talk to your doc- tor about how they might be affecting your symptoms, the effects of your med- ications, or your overall heart health.
• Caffeine in coffee, soft drinks, tea, or chocolate
• Alcohol
• Tobacco, including secondhand smoke
• Diet pills
• Some over-the-counter cough and cold remedies (especially those with pseudoephedrine)
• Some herbal remedies (such as ephedra or ephedrine)
• Prescription drugs (such as antianxiety, antipsychotic, or antiarrhythmic medications)
• Bronchodilators, whether prescription or over-the-counter
• Automobile emissions
• Industrial pollution
• Paint thinners
• Propane gas
• Hazardous substances in the workplace (such as carbon monoxide)