Atrial fibrillation (also known as A-Fib, AFib, or AF) is a medical condition that causes a rapid and irregular heartbeat (arrhythmia).
Sometimes the heartbeat can also be slow, but irregular. When it's rapid, it involves the heart’s two upper chambers (atria) contracting very quickly and irregularly from disorganized electrical signals.
As a result, the heart's upper and lower chambers don't operate like they should, and blood can pool in the atria above them. That pooling can result in blood clots that can cause a stroke or heart failure.
Causes of Atrial Fibrillation
The exact cause of Afib in most cases is unclear. There are certain risk factors that are believed to contribute to it. Age is the primary risk factor of Afib, as it is extremely rare to occur in young people. Other risks include:
- High blood pressure
- Excessive alcohol consumption
- Inactivity / sedentary lifestyle
- Heart disease
- High cholesterol
Types of Atrial Fibrillation
With Paroxysmal AFib, the heart usually returns to its normal beat within seven days of the condition's onset. Most people who have this condition only experience it a few times per year. Symptoms can be unpredictable.
Persistent AFib involves an irregular heartbeat lasting more than seven days. Treatment is usually required.
Permanent AFib is of an indefinite duration. When attempts to return the patient to a normal heartbeat have failed, the patient and doctor agree to discontinue attempts to restore the normal heartbeat and resort to medical alternatives.
Atrial Fibrillation Symptoms
Permanent AFib is easy enough for a doctor to diagnose. AFib ordinarily causes the heart's lower chambers (ventricles) to contract at a faster than normal pace. The ventricles can't fill with sufficient blood. As a result, they might not be able to pump a sustainable amount of blood to the lungs and body.
A person experiencing AFib might not even feel any symptoms at all. When experienced, symptoms include:
- Shortness of breath
- Chest pain
- Passing out
Many people experience onsets of AFib. They can be so brief that most people do not realize it, particularly if there are not any symptoms.
Complications of Atrial Fibrillation
The two most common complications of AFib are a stroke and heart failure. Should pooling of the blood occur in the upper atrial chambers, a blood clot could develop. If that blood clot breaks away and travels to the brain, a stroke will occur. To reduce the chance of a stroke, blood thinning medications like Warfarin are used in treating AFib.
Diabetics and people with high blood pressure are at an even higher risk of stroke if they experience AFib.
Heart failure is the second most frequent complication of AFib. Because the ventricles can't fill with blood, the heart beats at a very high rate. The combination of a lack of blood and rapid heartbeat can result in heart failure.
Diagnosing Atrial Fibrillation
The rapid and irregular heartbeats of AFib can be diagnosed with a stethoscope or even by just taking a patient's pulse. What can make a diagnosis of AFib difficult is the nature of the condition because the heart will often return to its normal beat after a very short episode.
Diagnosis is then left to an electrocardiogram (ECG or EKG), a 24-hour heart monitor or by wearing a patient-activated recorder for up to a month.
Other more complicated or invasive diagnostic methods are also available.
Treatment of Atrial Fibrillation
The treatment for Atrial Fibrillation depends on many factors such as the root causes of Afib, how long you've had it, and your overall health and ability to tolerate certain procedures and medications.
The overall goal is to cure or control the abnormal heart rhythm and to prevent any complications such as blood clots and strokes.
There are different kinds of medications that would be prescribed. Each does something different.
Since Afib causes blood to pool in the heart, blood clots can form and travel to the brain causing a stroke. Warfarin, aspirin or other antiplatelet / anticoagulants are often prescribed to prevent blood clots and stroke.
Heart Rate Medications
Beta blockers are a class of drugs that "block" the effects of epinephrine (adrenaline). As a result, the heart rate is slowed down.
Calcium channel blockers "block" calcium from entering the heart muscle and vessels. This results in muscle relaxation which allows the blood to flow better.
Cardiac glycoside is a plant-based drug that slows down the heart rate. These drugs include Digoxin, Digitoxin, and Ouabain. Like Warfarin, there is a very narrow therapeutic range, and going outside the range can result in severe complications including death.
Heart Rhythm Medications (antiarrhythmic)
Sodium channel blockers "blocks" sodium from entering cardiac cells. Sodium normally acts like a conductor and by decreasing its presence it helps slow the heart's ability to conduct electricity.
Potassium channel blockers "blocks" potassium from entering cardiac cells. It is similar to sodium channel blockers in that they interfere with the heart's electrical conduction.
Electrical Cardioversion is a procedure designed to "reset" your heart rhythm. The doctor will perform the electrical shock via paddles placed on your chest, or on your chest and back after you have been sedated. The shock will temporarily stop and then restart your heart beat.
An Electrical Cardioversion may cause a stroke if you had a blood clot in your left atrium at the time of the procedure. In order to prevent this, your doctor may prescribe Warfarin before the procedure or perform a Transesophageal echocardiography which checks for blood clots.
Pharmacologic Cardioversion also performs a "reset" to your heart's rhythm, but does so using antiarrhythmic medication.
A Pharmacologic Cardioversion also poses a risk of stroke if you had a blood clot in your left atrium at the time of the procedure.
A Pacemaker is a small device implanted inside the chest to control the "pace" of the heartbeat.
The pacemaker is inserted on the left side of the chest beneath the clavicle. The "leads" are wires attached to the pacemaker that sends and receives electrical impulses to the heart. The leads are fed through the subclavian vein and into the right atrium.
As with any surgical procedure, there are risks, but generally pacemaker implantation is considered a relatively simple procedure.
Something to note, however, is that pacemakers are electronic devices and can experience electronic interference with other electronic devices. People with pacemakers are advised to avoid machines like MRI's and take caution with using cell-phones.1
Catheter ablation is a procedure that destroys areas of the hearts tissue that is firing erratic signals.
It is performed by inserting thin wires, called a catheter, inside the groin or neck. The wires are then sent through a vein into the right atrium. Electrodes at the tip of the catheter send radio frequency electrical currents to burn the abnormal areas of the heart that are behaving abnormally.
As with any surgical procedure, there are risks, but incidences are rare.
Maze surgery is a procedure that creates a "maze" of new electrical pathways to block the erratic electrical waves the hear tis producing.
There are two types of maze procedures: mini-maze and open chest maze. Mini-made is less invasive and performed through a small incision in the chest. The open chest maze requires the chest to be opened. The maze is created by scaring the tissue, and thus, making it less conductive and acting as blockers.
As with any surgical procedure, there are risks. The success rate of the procedure is anywhere from 80 to 100%.2
Citations (view all)
- 1. "Interference with Pacemakers and Other Medical Devices." U.S. Food and Drug Administration. Accessed March 31, 2015. http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/HomeBusinessandEntertainment/CellPhones/ucm116311.htm.
- 2. "Atrial Fibrillation Surgery - Maze Procedure." The Society of Thoracic Surgeons. Accessed March 31, 2015. http://www.sts.org/patient-information/arrhythmia-surgery/atrial-fibrillation-surgery.