Atrial fibrillation is a type of arrhythmia or abnormal beating of the heart. Normally, the heart’s pumping motion is coordinated by electrical activity that moves in an organized fashion from the top of the heart (the sinus node) through the middle of the heart (the atrioventricular node) and to the bottom of the heart (through the Bundle of His and Purkinje fibers). First the electrical impulse reaches the atria at the top which causes them to contract, filling the ventricles with blood. Then, the electrical impulse travels to the bottom of the heart, causing the ventricles to contract, which forces blood out of the heart and through the lungs and body. A normal heart rate runs at 60 to 100 beats per minute though athletes may naturally have lower heart rates. In atrial fibrillation, the heart can beat from 100 to 175 beats per minute which is too fast. With atrial fibrillation, this normal electrical activity does not work exactly right. Instead of working in a coordinated fashion, the two small chambers at the top of the heart (the atria) quiver in place. This quivering motion of the upper chambers of the heart causes the lower chambers of the heart (the ventricles) to beat in an irregular pattern that may be too fast. Atrial fibrillation can either come and go (paroxysmal) or can be constant (chronic). Most of the time atrial fibrillation is not a problem and may not even be felt. Other times, a patient may notice lightheadedness, palpitations, shortness of breath or chest pain. Unfortunately, atrial fibrillation can cause life-threatening complications like a stroke. Atrial fibrillation can be caused by a number of factors such as damage to the heart muscle (like scarring from a previous heart attack), elevated blood pressure, abnormal heart valves, diabetes, heart disease, hyperthyroidism (elevated thyroid activity), smoking, drug use, stress, sleep apnea, alcohol, caffeine, cocaine, heart surgery, lung disease, sick sinus syndrome and some herbal supplements. Atrial fibrillation can even lead to more serious problems like heart failure and strokes.
Palpitations, fluttering sensation the chest, fast heartbeat, shortness of breath, lightheadedness, chest pain, dizziness, fainting, low blood pressure, confusion
Diagnosis of an arrhythmia begins with your doctor taking a history and physical exam. Your doctor will pay particular attention to your heart sounds and pulse rate. Your doctor will want to perform an electrocardiogram (EKG). An EKG is done by placing small stickers over the chest which are attached to a machine to create a picture of the electrical activity of the heart. This picture can tell a cardiologist what type of rhythm the heart is in as well as any areas that might not be working properly. An EKG can help determine how fast your heart is going and help determine your treatment. Your doctor or cardiologist may also recommend a Holter monitor that is worn for 24 hours to record the heart’s activity or an event monitor which begins recording when the patient feels an abnormal heart beat and a pushes a button to record. For atrial fibrillation, it is important to look at the pumping function of the heart, most commonly by using an echocardiogram (ultrasound or sonogram) of the heart. Your cardiologist may recommend electrophysiologic testing or “mapping” of the electrical currents in the heart which helps show the cardiologist what areas need to be treated to prevent further electrical abnormalities. This testing is done by threading thin catheters to the heart which send small electrical impulses into the heart to see where they go, which is turned into a map of the heart’s electrical pathways. A chest x-ray can also be useful for your doctor to look for any lung abnormalities that may be causing your atrial fibrillation.
Many treatment options exist for atrial fibrillation. If there is an underlying cause of your atrial fibrillation, like smoking or overactive thyroid, your doctor will treat or help you control those factors. The goals for atrial fibrillation treatment include controlling the rate of the heart or the rhythm of the heart but also preventing blood clots from forming in the quivering left atrium which can become dislodged and go to the brain, causing a stroke. If possible, your cardiologist may want to try resetting the heart’s natural rhythm with a procedure called cardioversion. Chemical cardioversion involves injecting the patient with a medication that tries to reset the natural pattern of the heart. Electrical cardioversion involves shocking the heart with an electrical current to reset the electrical activity of the heart (after you have medication to help you relax and minimize any associated pain). Before cardioversion, your cardiologist will either recommend you take a blood-thinning medication called warfarin (Coumadin) or that you have an echocardiogram of the heart taken through the esophagus (while you are asleep) to ensure that you don’t have any blood clots sitting in the left atrium that might dislodge and cause a stroke. Your cardiologist may recommend medications to help keep your heart in a normal rhythm after the procedure is done. Your cardiologist may recommend medications to control your heart rate (to ensure it does not go too fast) like digoxin, calcium channel blockers, and beta-blockers. Other medications aim to change the rhythm of the heart, not allowing it to be in an abnormal rhythm. If medications are not effective for you, your cardiologist may recommend AV node ablation (a procedure to burn the atrioventricular node) followed by placing a pacemaker in the chest to control the heart rate. If a source of your abnormal heart beat is discovered through electrical mapping of the heart, your cardiologist may be able to lightly burn the abnormal cells causing the alternate electrical pathway and stop the abnormal rhythm, a procedure called ablation. Surgical options may also be available to treat arrhythmias. One surgery is called the Maze procedure (a procedure during which a series of small incisions are made in the atrium to create tiny scars that will impede the abnormal electrical circuit. The Maze procedure is very successful, but requires open heart surgery so is generally tried after other options fail. For people with certain risk factors, thinning the blood is important to prevent strokes. Thinning of the blood can be done with warfarin (Coumadin) which needs to be monitored at least monthly, or with medications that are injected twice daily called low molecular weight heparin. You should discuss all of your diagnostic and treatment options with your doctor or cardiologist.
