Atrial Fibrillation is the most common arrhythmia, and it affects millions of patients worldwide. Over two million Americans are living with atrial fibrillation. Although it is not life-threatening, it can cause uncomfortable symptoms. It can also cause other problems such as congestive heart failure and stroke. This section explains how atrial fibrillation differs from the heart’s normal electrical process.
There are four chambers in the heart, two atria which are the upper chambers of the heart and two ventricles which are the lower chambers of the heart. There is a right and left atrium and a right and left ventricle. Each heartbeat begins with the natural pacemaker of the heart, the sinoatrial (SA) or sinus node, located in the upper portion of the right atrium. The sinus node normally sends out an electrical impulse that spreads throughout the atria to an area between the two atria called the atrioventricular (AV) node. The AV node, the electrical hub of the heart, connects to a group of special electrical fibers (left and right bundle branches) that conduct the impulse to the ventricles below. As the electrical impulse travels through the heart, the muscle cells contract. First the atria contract, pumping blood into the ventricles, followed by contraction of the ventricles, sending blood to the rest of your body.
With atrial fibrillation, there is an abnormal focus of electrical impulses that cause chaotic electrical activity in the atria. This chaotic electrical activity causes the atria to quiver, or fibrillate, rather than contract in a regular pattern. The storm of electrical impulses is sent to the AV node which conducts some of the impulses through to the ventricle. If the AV node conducts these impulses rapidly the ventricular rate (pulse) can be very fast and irregular.
Since the atria are not emptying properly when in fibrillation, blood can stagnate in the left atrium and form small blood clots. These clots can travel (embolize) to small vessels in the head and cause a stroke. The likelihood of stroke in patients with atrial fibrillation is five times higher than in the general population. Although about half of all blood clots related to atrial fibrillation result in stroke, clots can travel to other parts of the body (kidney, heart, intestines) causing problems. It is important for people experiencing atrial fibrillation to be treated with drugs that reduce the blood's ability to clot (anticoagulant) such as warfarin (Coumadin) or aspirin.
Atrial fibrillation can also decrease the heart's pumping ability by as much as 20%-30% Atrial fibrillation, when it results in an untreated a fast heart rate over a long period of time, can result in heart failure.
The risk of atrial fibrillation increases with age, particularly after age 60. Atrial fibrillation is associated with many conditions, including:
In at least 10% of people with atrial fibrillation, no underlying cause is found. In these people, atrial fibrillation may be related to alcohol intake, excessive caffeine use, stress, metabolic imbalances, or severe infection. In addition, there is a hereditary form of atrial fibrillation. In many people, no cause can be found.
Some people experience atrial fibrillation on and off, terminating without treatment. This is classified as paroxysmal or intermittent atrial fibrillation. Some people experience atrial fibrillation that persists and needs to be terminated with some type of treatment to revert to normal sinus rhythm. That is classified as persistent atrial fibrillation. Some people are always in atrial fibrillation, and even with treatment they stay in atrial fibrillation. That is classified as permanent atrial fibrillation.
These symptoms may be a result of the irregular heart beat itself, the rapid pulse that is associated with atrial fibrillation, or both.
Diagnosis of Atrial Fibrillation
Three tests are used to diagnose atrial fibrillation, including:
Treatment of Atrial Fibrillation
There are two general management strategies for the treatment of atrial fibrillation. The first is to restore a normal heart rhythm (rhythm control), and the second is to leave the atria in fibrillation but control the heart rate (rate control). There are many options available in these strategies including medication, cardioversion, ablation therapy, device therapy, and surgery. In either approach, a strategy to prevent stroke is implemented.
Medications are prescribed in the management of AF depending on the overall treatment goal. If the goal is to restore normal heart rhythm, a type of drug called an antiarrhythmic is prescribed. If it's not possible to achieve this goal, doctors will try to manage your disease by slowing down the heart rate. In both cases, your doctor will give you medications called anticoagulants to decrease blood clot formation.
Cardioversion is a procedure in which normal heart rhythm is restored by either delivery of an electrical shock delivered across the chest (DC cardioversion) or administration of medications (chemical cardioversion). DC cardioversion is a same-day procedure in which a patient is brought to the electrophysiology laboratory and first administered a short-acting general anesthetic, after which electrical energy is applied to the chest using paddles or specialized pads that connect to a defibrillator. The whole procedure takes about 5-10 minutes. Because anesthesia is used, it is painless. In the case of chemical cardioversion, which is painless, no anesthetic is necessary, and a medication is given either intravenously or orally.
There is a very small risk of stroke from cardioversion. Therefore, before cardioversion is performed, the doctor must be certain that there is a very low chance that a blood clot is has developed in the left atrium, and that cardioversion therefore has an acceptably low risk of stroke. There are three situations in which this is the case:
If none of these can be confirmed with certainty, the patient would first need to either receive anticoagulation for 3-4 weeks prior to cardioversion or undergo an imaging study to demonstrate that no clot is present. This imaging procedure is called a transesophageal echocardiogram (TEE).
A TEE is an ultrasound procedure performed by a specially trained cardiologist. An ultrasound probe for placed into the esophagus after sedating the patient and spraying the back of the throat with a local anesthetic. The probe produces images of the inside of the atria which are displayed on a television screen. The doctor can see whether there is a thrombus (blood clot) in the atria, and (s)he can also look for other heart abnormalities. If no clot is present, the cardioversion is then performed.
Ablation therapy is an option for people who cannot tolerate medications or when medications fail to maintain normal heart rhythm.
Ablation of the AV node can help many of the symptoms of AF. However, AF does continue, and blood thinners are still needed to reduce stroke risk. The procedure requires sedation and overnight hospitalization.
For rhythm control, the regions of abnormal impulses that cause atrial fibrillation are targeted for ablation, a procedure called pulmonary vein isolation. If successful, this procedure can cure atrial fibrillation.
Pulmonary vein isolation/Left atrial catheter ablation
Recent research shows that the predominant source of electrical instability in atrial fibrillation is at the opening of each of the pulmonary veins, which return blood from the lungs to the left atrium. There are four pulmonary veins which insert into the left atrium.
Once the doctor has decided that pulmonary vein ablation may help you he will plan to do an electrophysiology test and ablation procedure. This procedure is performed in a special laboratory under sterile technique and using general anesthesia. You will be asked to prepare for this procedure by having blood work done and possibly a special chest scan called a CT (computerized tomography) scan. A transesophageal echocardiogram (TEE) is done routinely either the day of or the day before the ablation to ensure that there are no pre-existing blood clots within the heart chambers. You will be told when to come to the laboratory. You will be expected to fast (nothing by mouth) from midnight on the morning of the procedure and instructions in reference to your medications will be given in advance.
The laboratory has a lot of specialized equipment including television monitors and X-ray machines. The room is sterile, so the doctors wear gowns, masks, and head gear. You will be covered with special drapes; and an intravenous line (small tube in your vein for administering medications and fluid) will be placed as well as a clip on your finger to monitor the level of oxygen in your bloodstream. There may be other people in the room with your doctor, including 2 nurses and other doctors, who will assist him with your procedure. There may be an anesthesiologist present who is there to monitor you.
After injecting a local anesthetic, the doctor will insert catheters into the veins in your groins, and sometimes neck, and advance them, under fluoroscopic (X-ray) guidance into your heart and through the septum (the wall between the right and left atria) to the left atrium to access the openings to the pulmonary veins. After positioning the catheter and mapping (measuring the abnormal electrical triggers), he will pass radiofrequency energy through the special catheter. This allows the tip of the catheter to heat up and destroy a small amount of tissue. Ablation cauterizes abnormal arrhythmia-causing tissue, making it incapable of transmitting electrical impulses.
Atrial fibrillation ablation is a “cutting-edge” procedure which is not routinely performed at most arrhythmia centers. In order to perform this procedure with maximum safety and accuracy, advanced imaging, mapping, and recording equipment are required. The EHMC laboratory is equipped with several specialized systems to allow your doctors to accurately image the heart, track the catheters in space, and deliver ablation lesions to precise locations. These include a state-of-the-art X-ray system, phased array intracardiac ultrasound, the Biosense® electroanatomic mapping system, and the Endocardial Solutions® 3-dimensional mapping systems. (PUT IN GRAPHICS)
After the Procedure
You will be brought to a recovery area, adjacent to the EP lab, and monitored while the sedating medications wear off before you are sent to hospital room where you will stay and be monitored overnight. It is not unusual to feel some discomfort in your chest area and in your groin areas where the catheters were inserted. You may feel some skipped beats. When you are ready to go home the next day you will be given special instructions about how to take care of your groin, what medications to take and what symptoms you may expect to feel.
It is not unusual for your arrhythmia to recur in the first two to four weeks after the ablation. It can take 1-3 months for the ablation scars around the pulmonary veins to totally heal and for us to know if the procedure is successful. If your atrial fibrillation recurs, don't be alarmed, as it is part of the evolving process for healing after the ablation. If it is persistent, you should call us. You will probably go home on an antiarrhythmic medication to allow the healing process to take place while maintaining regular sinus rhythm. Depending on your post procedure course, you may be on this medication for 1-3 months.
To prevent any emboli from developing after the procedure you will be placed on warfarin (Coumadin) for several months. It takes 3-4 days for the effects of warfarin to be therapeutic. We usually bridge that gap with a faster acting blood thinner called Lovenox. This requires administration of a small injection twice a day for 3-5 days after the procedure. You will be fully instructed on how to do this prior to discharge. It is always important to have your blood work checked after the procedure, as instructed at discharge, for us to properly instruct you on how much warfarin (Coumadin) to take.
You will be asked to come to the office in about 2 weeks after the procedure so we can see how you are doing. You will have an ECG done at that time and you will be asked if you have had any symptoms, specifically how often and for how long. Two weeks later, we will want to obtain a 24 hour Holter monitor recording of you rhythm. You will be seen again in our office two weeks after that as we monitor how you are doing.
The Arrhythmia Center number is 201-894-3533 and can be called Monday-Friday, 9AM-5PM. For after-hours emergencies, our doctors can be paged at 201-894-3000.