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Atrial fibrillation is an irregular rhythm that occurs in the upper chambers of the heart. Sometimes the rhythm comes in patients with no heart abnormalities whatsoever. Other times, a history of high blood pressure or other cardiac abnormalities can lead to stiffening of the heart muscle. This in turn causes the atrium (top chamber of the heart) to stretch out. The increased stretch in size of the atrium predisposes these patients to the arrhythmia. Why do we treat atrial fibrillation? There are two reasons that we treat atrial fibrillation. First, the irregular pattern of beating and the increased heart rate frequently cause patients to be symptomatic with palpitations (heart pounding), fatigue and decreased ability to exercise. Second, patients with atrial fibrillation have an increased risk of stroke. When the atria fibrillate (quiver), they no longer contract in a coordinated fashion. The consequence of the loss of atrial contraction is that blood flowing through the left atrial chamber can form small eddies and pools. In these regions of slow blood flow, a clot can form. In the worse case, the clot can break off and travel downstream (embolize), ultimately lodging in one of the smaller arteries in the system. If the clot happens to lodge in an artery in the brain, this can cause a stroke How are strokes prevented in atrial fibrillation? The mainstay for prevention of stroke in patients with atrial fibrillation is the use of blood thinners. Any patient who has a risk factor for stroke, including a history of heart failure, high blood pressure, age over 65 years, diabetes, or prior stroke needs to be treated with Warfarin (Coumadin) blood thinner. It is very important that the Prothrombin Time (PT) International Normalized Ratio (INR) be maintained at a level of at least 2.0 to gain benefit from the drug. The level should not routinely exceed 3.0 because the risk of bleeding complications start to increase slightly as the PT/INR level gets higher. If the patient is undergoing an electrical cardioversion (a shock conversion of atrial fibrillation to normal rhythm), it is necessary to have a therapeutic PT/INR level for at least three consecutive weeks in order to safely perform the procedure. If the heart is normal and there are no risk factors for stroke, then your doctor may choose to treat you long term with aspirin instead of Coumadin. The proper aspirin dose for stroke prevention in atrial fibrillation is 325mg (an adult size aspirin tablet) daily. What is an electrical cardioversion and do I need it? Sometimes patients will have atrial fibrillation that is persistent. That is to say, the atrial fibrillation does not terminate by itself. In the cases of persisting atrial fibrillation, it may be necessary to shock the heart in order to "bump" it back into a normal rhythm. It is usually a good idea to try at least once to restore normal rhythm with cardioversion. Some patients undergo cardioversion on several occasions. What treatments are available for atrial fibrillation? Therapies that are used to treat atrial fibrillation are varied. Sometimes the goal is just to keep the heart rate controlled and regular during episodes of atrial fibrillation to minimize symptoms. Rate controlling drugs are used for this purpose. If patients are symptomatic despite the use of rate controlling drugs, stronger medications called suppressive anti-arrhythmic drugs may be employed to prevent the arrhythmia recurrence all together. If medications are unsuccessful, the patient may be a candidate for a catheter procedure called radiofrequency catheter ablation. One type of catheter ablation is designed to improve symptoms but not to eliminate the atrial fibrillation. This is called AV junctional ablation (or sometimes AV nodal ablation). Another type of catheter procedure is curative catheter ablation. This procedure is designed to eliminate the atrial fibrillation completely. Drugs that are used to slow the heart rate response to atrial fibrillation include beta-blocking drugs, calcium channel blocking drugs and digoxin. These drugs are very safe and are usually well tolerated. A large trial of over 4,000 patients (The AFFIRM Trial) demonstrated that heart rate control with anti-coagulation is a safe and effective long-term strategy in the management of typical patients with atrial fibrillation. This is the standard approach that is offered to most patients with arrhythmia recurrence. Suppressive anti-arrhythmic drugs: Suppressive anti-arrhythmic drugs are agents that are specifically designed to prevent the recurrence of atrial fibrillation. These are powerful drugs that have effects on both the heart as well as other organs in the body. Typical drugs in this category include dofetilide (Tikosyn), sotalol (Betapace), flecainide (Tambocor), propafenone (Rythmol), and amiodarone (Cordarone, Pacerone). These drugs usually require close physician follow-up and sometimes require hospitalization for drug initiation. They all have some potential for side effects and adverse reactions but they are generally well tolerated. Atrial fibrillation is completely suppressed in 50 to 70% of patients. Although patients often feel better on these drugs once their atrial fibrillation has been suppressed, there may be a small, but real, long-term risk caused by these agents. The decision about the use of these drugs needs to be made on a case-by-case basis. AV junctional ablation with pacing: AV junctional ablation with pacing is another mode of heart rate control when drugs are ineffective. This involves a catheterization and surgical procedure whereby the physician inserts small electrode catheters through the vein in the leg into the heart. One wire is used as a temporary pacemaker and the other wire is positioned next to the body's electrical conducting system. A small pulse of radiofrequency electrical current is passed through this catheter into the heart. A small burn is created at the AV junction. This burn results in an interruption of electrical conduction from the upper chambers (atria) that are in fibrillation to the lower chambers ventricles that are the main pumps. Once this electrical connection has been cut, the ventricles pump at a slow and steady rate no matter what rhythm the atria are following. After this procedure, the patient is left with a heart rate that is too slow for normal daily living. For that reason, the ablation is almost always followed by implantation of a permanent pacemaker. This is an operation that requires a small (1-1 ½ inch) incision in the left shoulder. A small electronic device is inserted into a pocket under the skin and is attached to one or two wires that are passed through the veins down into the heart. From that point forward, the heart rhythm is controlled entirely by the pacemaker. This restores a normal heart rate and a regular pattern of heartbeat. The advantage of AV junctional ablation and pacing is that the patient's medications can be significantly streamlined, and their symptoms are almost always improved. The disadvantage is that the patient becomes pacemaker dependent. Also, the atria continue to fibrillate, and therefore life-long treatment with Coumadin anticoagulation is needed. Nevertheless, this therapeutic approach has been used since 1981 and has been effective and well tolerated by many patients with atrial fibrillation. Patients who have significant symptoms due to their atrial fibrillation may be candidates for attempted curative catheter ablation of their arrhythmia. The goal of curative catheter ablation is to interrupt the transmission of atrial fibrillation impulses from their source of origin, or to interrupt the electrical conduction of atrial fibrillation impulses through the heart in order to disrupt them to the point where the arrhythmia can not continue. In order to accomplish this, it is necessary to put catheters into the left atrial chamber, which is the heart chamber responsible for this arrhythmia in the great majority of cases. Pulmonary vein isolation is a technique where by an ablation catheter (a small wire placed through the veins up into the heart) is used to deliver pulses of radiofrequency current in a circle around the vein. These small burns link up to form a continuous line of ablation at the base of the vein where it meets the atrial body. At William Beaumont Hospital, we place an echocardiographic imaging catheter into the heart and monitor the movement of the catheter within the heart by the echo images, by x-rays and also by a three-dimensional electronic global positioning system in the heart. By doing this, we can assure that the burns form a narrow line and are successful in electrically isolating the veins from the rest of the heart. Keep in mind that the veins still function normally as pipes carrying blood from the lungs to the rest of the heart, but they are now electrically disconnected. After the electrical disconnection, any irritable sites within in the vein walls can fire rapidly, but the rapid rhythms are not transmitted to the rest of the heart. The pulmonary vein isolation is most effective in younger individuals who have frequent short burst of atrial fibrillation and otherwise normal hearts. In many patients, particularly those with some enlargement of their left atrial chamber, the atrial fibrillation is more persisting or more resistant to treatment. It is usually the case that there are waves of atrial fibrillation traveling through the left atrial chamber that allow the rhythm to continue even if the pulmonary veins are completely isolated. In these patients, supplemental linear atrial ablation is performed. Linear atrial ablation is simply the creation of a line of scar connecting to anatomical structures in order to create barriers to electrical conduction. The standard approach at William Beaumont Hospital is to complete pulmonary vein isolation with encircling lesions. Then, linear lesions are created from the left lower pulmonary vein border down and connecting to the mitral heart valve. A second connecting line is created between the left upper vein and the right upper vein. This, in the conjunction with the encircling pulmonary vein lesions, creates a large line of block through the middle of the atrium and then disrupts the ongoing wave activity of the atrial fibrillation, preventing its recurrence. In addition, a short linear ablation is often performed in the right atrial chamber. This so-called "flutter burn" disrupts a common circuit of arrhythmia that causes the rhythm atrial flutter, but also helps to prevent the abnormal rhythm of atrial fibrillation. What needs to be done in preparation for curative atrial fibrillation ablation? Generally, you will meet with your doctor before the procedure and discuss the risks, benefits and expectations regarding the procedure. At some point before the procedure a magnetic resonance imaging (MRI) scan of the heart is performed. This is used to detail the anatomy of the left atrial chamber. Your doctor may instruct you to discontinue one or more of your routine medications several days before the procedure. If your taking Coumadin, this will need to be discontinued five-days before the procedure. In some cases when risk factors for blood clot in the heart are present, a transesophageal echocardiogram (TEE echo) will be performed either the day of the procedure or a couple days before. This echo involves passing a small probe down the throat into the esophagus (the food tube). A view from this angle gives a very clear picture of the left atrial chamber and allows your doctor to prove definitely that there is no clot in the left atrial chamber. Between the time of your TE echo and the ablation procedure, you may need to use shots of Enoxaparin (blood thinner-Lovenox) in order to make sure that no new blood clot forms. What happens on procedure day? You will be instructed to arrive at the Heart Center at a designated hour. You and your family will be escorted up to the 8th floor where you will change your clothes and meet the staff. A small intravenous line will be started in your arm for administration of medications. The family will be escorted to the waiting area and you will be taken into the procedure room. The procedure room has x-ray equipment as well as all of the monitoring equipment that is necessary for your safety during the procedure. You will receive sedation and will probably be asleep for most of the procedure. A small tube will be passed into your bladder so that you will not need to worry about urination during the course of the procedure. The groin areas will be scrubbed with sterile soap and you will be covered with sterile sheets and towels. The groin areas will be numbed and small needle punctures into the vein will be performed. Small tubes (introducer catheters) will be inserted into the veins and advanced into the heart under x-ray. Because the ablation needs to be performed in the left atrial chamber, a procedure called transeptal catheterization will be performed. With this procedure, two small puncture holes are made in the thin muscular wall that separates the right from the left atrial chamber. The ablation catheter and an echo catheter to allow for visualization of the heart from the inside out are inserted into the left atrial chamber. The movement of the ablation catheter is monitored with a global positioning system (the Endocardial Solutions, Inc. NavX system). The ablations are created as described above. During the course of the procedure, a high dose of blood thinner is administered. After completion of the ablations, the catheters are withdrawn. Some additional electrical testing maybe performed by pacing the heart. Some medication may be administered to increase the heart rate and try and initiate the rapid rhythm. At the completion of all the testing, the electrical catheters will be withdrawn and the small introducer catheters will be left in the vein until the effect of the blood thinner decreases. You will be transferred to the hospital room where you will be monitored closely. Once the blood has thickened, the introducer catheters will be removed and firm pressure will be placed over the puncture sites to prevent any bleeding. You will need to stay flat in bed for 6 hours after the introducer sheaths are removed. After the sheaths are removed, you will receive a shot of enoxaparin (Lovenox) blood thinner to reinitiate anticoagulation and prevent blood clot formation. Your Coumadin will be reinitiated that evening. You will be watched overnight and be allowed to walk around the morning after the procedure. If you are feeling well, you will be ready for discharge from the hospital. What can I expect after hospital discharge? Patients are usually somewhat tired and sore the day after the procedure. However, most patients feel back to normal within four or five days from hospital discharge. Some residual tenderness at the catheter insertion site may stay with the patient for a week or more. Occasionally there is some bleeding under the skin at the catheter insertion site (hematoma). In this case, there are sometimes large black and blue areas that come to the surface of the skin in the days following the procedure. If there is no increased swelling or pain, you should not be alarmed by this finding. On rare occasions after hospital discharge, there can be some recurrence bleeding from the puncture site. This usually appears with an increase in swelling and a sudden increase in discomfort at the insertion site. If there is more swelling or pain, you should return to William Beaumont Hospital or your local physician for evaluation. It is imperative that you contact your Beaumont Heart Rhythm doctor if you have required additional treatment after the ablation procedure. It is very typical that patients will have some chest discomfort after the ablation that is worsens by a deep breath or change in position. This usually goes away after a couple of days, but in some cases can persist two-weeks or longer. This is caused by inflammation from the ablation that was performed in the heart. It is very common for patients to have occasional jumps and skips in their heart rhythm after a successful procedure. Atrial fibrillation may recur in the first month after the ablation as a consequence of the inflammation of the heart. An early recurrence of atrial fibrillation does not necessarily mean that the procedure has failed. If you think that the rhythm has recurred, you should contact your doctor for further evaluation. What is the likelihood of procedure success? Curative atrial fibrillation ablation is still in evolution. The success rates that are being achieved today are much better than those that were observed five-years ago when work in this area was first begun. Nonetheless, patients may have recurrences. The overall likelihood of success of the ablation procedure is about 75%. In addition some patients will have improvement but not complete elimination of the atrial fibrillation. Some patients will have atrial fibrillation recurrence after an initial procedure, but will subsequently have elimination of the abnormal rhythm after a second "touch-up" procedure. The most common reason for procedure failure is that some areas of catheter ablation are damaged, but not completely destroyed and converted to scar. With time, these regions recover normal electrical activity. With that recovery, there is a gap in the ablation line (like a break in a fence) that allows the abnormal impulses to pass through. The likelihood of response to the procedure is in part determined by the shape and size of the heart as well as the pattern of atrial fibrillation. Patients with the highest likelihood of procedure success are those with completely normal hearts and frequent short bursts of atrial fibrillation. People with a lower likelihood of procedural success are those with significant enlargement of left atrial chamber and persisting atrial fibrillation. Your doctor will discuss the anticipated likelihood of procedure success with you in light of your individual characteristics. What are the risks of the curative catheter ablation? Presently, curative catheter ablation is still a technically demanding procedure. Because of the underlying atrial fibrillation and the catheter movement in the left atrial chamber, the patients undergoing this procedure have a slightly increased tendency for blood clot formation and stroke. For this reason, a great deal of attention is paid to minimize any risk of stroke complications. High doses of anticoagulation (blood thinner) are used during and after the ablation procedure. Following this protocol, the anticipated risk of stroke with this procedure is approximately 5 out of 1,000. Factors associated with stroke include greater degree of structural abnormality of the heart and older age. Because high dose of anticoagulation is used, the other major category of procedure related risk is the risk of bleeding. Bleeding can occur around the heart during the procedure. This requires insertion of a tube in to the space around the heart and withdrawal of blood from that space. Generally, the tube can be removed the following day and generally there are no consequences of this after hospital discharge. However, bleeding around the heart can lead to a more intense inflammatory reaction to the procedure and some ongoing medication maybe required for the first month or two after hospital discharge. The other site of bleeding that has been observed is at the puncture sites in the groin. Usually these sites of bleeding are self-limited and patients recover completely without further intervention. On rare occasion either a transfusion is required or an injection or compression of a bulge or hole in the vein wall is required to prevent further bleeding or discomfort. There are usually no long-term complications associated with bleeding from the groin. In addition to the bleeding complications, a long list of theoretical complications can occur. However, these have not been seen in past experience nor are they anticipated. Specifically, there is essentially no risk of needing to have a pacemaker implantation after a complicated procedure with curative atrial fibrillation ablation. Is curative atrial fibrillation ablation right for me? Curative atrial fibrillation ablation is considered to be an elective procedure. Presently, we have no data that states that atrial fibrillation ablation prolongs life or reduces the risk of stroke over the long term. We believe that ultimately this will be proven to be the case, but for now, we cannot state this as a fact. Therefore, the main reason to proceed with atrial fibrillation ablation is to improve symptoms. We have many examples of patients whose lives have been dramatically improved with a successful procedure. However, this cannot be guaranteed. It is important to recognize there is a small but real risk of complications, and the decision to undergo this procedure must only be made after carefully weighing the anticipated benefits versus the infrequent but real risks. Your doctor will be happy to discuss this decision with you in detail. |
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