Guide To Arrhythmias
|How Is An Arrhythmia Diagnosed?
If your doctor suspects an irregular heartbeat the initial goal is to determine the cause and whether or not arrhythmia treatment is necessary. He will also want to discover if it is causing symptoms of arrhythmia which put you at risk of more serious problems in the future. The electrocardiogram (ECG/EKG) is an important tool doctors use to diagnose and study the pattern of an arrhythmia. Other possible tests include the use of stress tests and ambulatory electrocardiography (AECG) - portable ECG devices which are worn by patients for monitoring over a time period. In cases of complex rhythm problems, specialized electrophysiological testing may be necessary. We discuss all these heart tests in more detail below.
An ECG (image) is a diagnostic tool which measures the electrical activity of the heart. Technically it can record the path and timing of your heart's electrical impulses from their point of origin at the sino-atrial node, through the atria, atrio-ventricular node and the ventricles. During an ECG test up to a dozen adhesive electrodes are stuck to specific locations on the chest, arms and legs. The test is completely painless and only takes a few minutes to perform once the electrodes are in place. You may need to go to hospital for the test, unless your doctor has the necessary equipment in his office. A standard ECG machine can only measure electrical activity at the point you undergo the test. As arrhythmias come and go they can elude detection by an ECG. For this reason it may be necessary to undergo further testing by wearing an AECG. Additionally, sometimes doctors may combine an ECG with an echo test (echocardiogram). An echo uses ultrasound scan technology to take images of the heart and surrounding tissue. A Doppler or transducer is moved over the chest and sends out sound waves towards the heart, which bounce back and are recorded in images on a screen.
Sometimes doctors will want a clearer picture of the heart than a regular echocardiogram can provide. This may be because images from the echo are not clear due to the patient's weight, body shape or other considerations. An alternative method of studying the heart is to thread a small probe through the mouth and down the esophagus. Once inside the stomach the probe can transmit images of the heart. The stomach is much closer to the heart so images are clearer than it would be by moving a transducer over the chest in a regular echo. This internal test is known as a transesophageal echocardiogram (TEE). During the procedure the patient will be given a light sedative so that they remain partially awake. Their throat will be numbed with an anesthetic spray. As the tube is inserted in the mouth you may feel like gagging, but once it is in place you will not feel any pain. At all times your heartbeat and blood pressure is monitored. Once the test is over you remain in hospital for monitoring for a few hours but can then go home.
An ambulatory ECG or AECG allows doctors to measure your heart's rhythm for longer periods of time as you go about your normal routine. They are like miniature electrocardiographs - electrodes placed on the chest are attached to a small monitor which itself is worn attached to a belt. A Holter Monitor (image) is worn for 24 to 48 hours and continually records the heart’s rhythm. Technicians will download the results at the end of the period and your doctor will check the printout for signs of arrhythmia and how often it is occurring. The pattern of the electrical activity recorded will also help to differentiate between the different possible types of arrhythmia. However, if your arrhythmia is very infrequent then Holter monitoring may not capture it. An Event Monitor is another type of AECG which allows recording for up to 30 days. If you sense symptoms are occurring you activate the record button. The monitor's recording system loops, continually recording and deleting, so that when you activate it, it can retrieve data from a few minutes before the symptoms started. This is an excellent way to determine the causes of arrhythmia which are intermittent.
A doctor may order an exercise stress test (image) if they suspect that symptoms are brought on by physical activity. During this test the patient has ECG electrodes attached to their skin. Their resting heart rate and rhythm is tested. Then they are asked to perform some exercise, usually walking on a treadmill or cycling a stationary bike. During the test their heartbeat, heart rate, blood pressure, vital signs, symptoms and recovery times are noted. The results are then compared.
For some people with complex heart rhythms, more detailed studies may be necessary for doctors to obtain a complete picture of the medical issues involved. In such instances electrophysiologic studies may be ordered. These tests require hospitalization and cardiac catheterization. During the procedure specialized cardiologist surgeons thread a long tube through the veins and emit controlled electrical impulses planting them directly in the heart. This helps to map the heart's electrical system to determine where the problem is and how it might be treated. The patient may be given medication to induce an arrhythmia or one designed to stop it in order to see which works best for them. Some arrhythmias may even be cured or treated during an electrophysiologic study. The recovery period will be similar to that for any cardiac catheterization procedure.
A tilt table test (image) is another type of electrophysiologic study. It is used to evaluate the cause of unexplained fainting (technically known as syncope) or lightheadedness. During the test the patient is strapped to a table which moves from a horizontal to a vertical position. Their heart rate and blood pressure are monitored throughout to test for reactions. Although the test is not painful many feel their heart rate changing speeds and this might be slightly alarming. They may also be given some drugs during the procedure to test for reactions. Depending on what is being studied, the test can take anywhere between 1 and 4 hours. In case of emergency all labs where these tests are carried out will have a defibrillator, a machine which restarts the heart with electric shock.
|Related Articles on Heart Arrhythmia Diagnosis
For about risks and diagnostic tests, see the following:
• Arrhythmia risk factors: Are you at increased risk?
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