Atrial Fibrillation
In this condition factsheet:
Diagnosing Atrial Fibrillation
When the heart beats faster than normal, it's called tachycardia. AF is one type of tachycardia. If too many impulses are allowed through to the ventricles, your heart rate may be greater than 100 beats per minute. Conversely, if not many impulses are allowed through, your heart rate may, in fact, be slow (this is called bradycardia).
The stethoscope is a valuable instrument when it comes to detecting arrhythmias like AF, but there are modern tests that can pinpoint the problem. The electrocardiogram (ECG) prints a graph of the heart's electrical activity using small electrodes taped to the chest. The pattern on these graphs reveals the type of arrhythmia and can help the doctor diagnose AF. Since the arrhythmia might not occur at the hospital, there are portable ECGs that you can bring home. Some are constantly turned on over a specified period of time (these are called Holter monitors), while others are turned on by you when you feel palpitations (these are called event monitors or loop records). Many modern smart watches or other wearable devices have a built-in, miniaturized ECG sensor that can measure the electrical pattern of your heart rate over a brief period of time, but these are not meant to replace clinical-grade ECG devices, and are instead only meant to provide an approximation of your heart rhythm.
Electrophysiologic study (EPS) is a more elaborate test. Thin tubes are inserted into a blood vessel in the leg and guided up to the heart. They hold electrodes that can find the heart tissue that may be overriding the signals from the sinus node.
Your doctor may also order blood tests to determine if another condition (e.g., thyroid hormone imbalances) is associated with your AF.
Treating and Preventing Atrial Fibrillation
There are three main strategies to manage AF:
- rate control (preventing the heart rate from going too fast)
- rhythm control (trying to change the rhythm from AF back to normal sinus rhythm)
- anticoagulation (prevent clot formation and strokes with the use of blood thinners)
For rate control, several medications exist to help slow down a rapid heartbeat. With this strategy, the goal is to reduce the amount of impulses passing through the AV node and to slow the heart rate down. It should be noted that AF is still present when using this strategy.
Beta-blockers (such as atenolol, bisoprolol, carvedilol, metoprolol*,) and specific calcium channel blockers (e.g., diltiazem and verapamil) are medications used for rate control for people with a variety of heart conditions. Calcium-channel blockers (e.g., diltiazem, verapamil) may also be used for rate control. Often, these medications can be used for more than one purpose (e.g., heart rate control, high blood pressure, heart protection after a heart attack). Another medication, digoxin, has been used to treat arrhythmias for over 200 years. It is derived from a substance called digitalis.
In certain people, the rate is too difficult to control with medications. In this case, a specialized cardiologist (an electrophysiologist) will put in a cardiac pacemaker and arrange to do a procedure called AV node ablation (burn) a few weeks later. With special tubes inserted into a vein in your leg, heat is applied around the AV node of the heart to block all passage of electrical signals. The pacemaker then controls your heart rate, making it beat regularly.
Rhythm control can be achieved in different ways. The process of bringing the rhythm back to normal is called cardioversion; if medications are used in this process, it is called chemical cardioversion. Medications called antiarrhythmics (e.g., amiodarone, sotalol, dronedarone) can convert an abnormal rhythm back to normal and prevent the abnormal rhythm from recurring. Alternatively, electrical cardioversion uses a machine called a defibrillator that gives a controlled electrical shock to the heart, converting the AF to a normal rhythm. Patients are given an anesthetic so they do not feel anything during the procedure.
A technique developed by electrophysiologists called pulmonary vein ablation (or pulmonary vein isolation) is also used. Using special catheters placed in the heart, doctors either ablate (burn) areas that cause AF or isolate the area so that it does not affect the other parts of the atrium. This option may offer a "cure" to AF that the other options cannot offer.
Anticoagulation helps prevent the formation of blood clots and is critical for people with AF because of the increased risk of stroke. In order to prevent blood clots, doctors often recommend medications that limit your blood's natural ability to clot, often called blood thinners (although they do not actually thin the blood). These may include anticoagulants (such as warfarin, dabigatran, rivaroxaban, apixaban, and edoxaban) or antiplatelet medications (such as ASA). Depending on your risk of developing a clot, your doctor may recommend either an antiplatelet or anticoagulant medication. Although the risk of bleeding increases with the use of these types of medication, the protection they offer to prevent stroke and other blood clot-related conditions most often outweighs the risk.
All material copyright MediResource Inc. 1996 – 2024. Terms and conditions of use. The contents herein are for informational purposes only. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Source: www.medbroadcast.com/condition/getcondition/Atrial-Fibrillation
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