ATRIAL FIBRILLATION
WHAT IS IT
RECOGNIZE THE SYMPTOMS
WHAT CAUSES IT
HOW IS IT DIAGNOSED
MEDICATION OPTIONS
HOW IS IT CURED
CATHETER ABLATION
THE "WOLF MINI-MAZE"™
What is AF ?
AF is one of the most common heart conditions, affecting 4% of the adult population. Characterized by a rapid, irregular heartbeat, AF is due largely to abnormal electrical impulses that cause the atria of the heart to quiver when it should be beating steadily. Blood flow is reduced. It is not completely pumped out of the two small upper chambers of the heart, the atria, impacting cardiac performance and also allowing the blood to pool and potentially clot. Thorough testing by your health care provider can spot abnormalities in the heart's rhythm before any obvious symptoms are noticed.
The animation below illustrates a heart in normal sinus rhythm, in AF and in atrial flutter.
SINUS (NORMAL) ATRIAL FIBRILLATION ATRIAL FLUTTER
Even steady beat Uneven skips beats Extremely rapid uneven beats
Do you know how often your heart beats?
At rest, a normal heart beats approximately 60 – 100 times per minute. However, in a person with AF, that heart rate can skyrocket to 180 or even higher.
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Recognizing the symptoms
Whether it's caused by nerves, exercise or too much caffeine, most people experience a racing heart from time to time. Most cases are harmless. But AF is an actual medical condition and it may often be long lasting. Some people with AF experience no symptoms at all. But for others, AF may cause:
Exercise intolerance
Fatigue
Severe shortness of breath
Chest pain
Palpitations
Light-headiness
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What causes atrial fibrillation?
Your heart is divided into four chambers: the two upper chambers called atria, and two lower chambers called ventricles. In order for blood to be pumped through your body, a group of cells sends electrical impulses to the atria that tells your heart to contract. Contractions of the heart send approximately five quarts of blood through your body every minute. In people with AF, however, the impulses are sent chaotically. The atria quiver instead of beat; the blood isn't completely pumped out and may pool and potentially clot.
Are you at risk?
The older you are the greater is your chance of developing AF. AF occurs more commonly in women than in men. According to the Framingham Heart Study (http://circ.ahajournals.org/cgi/content/full/110/9/1042) AF is associated with a higher risk of death for women than for men. You are also at greater risk if you suffer from an overactive thyroid, high blood pressure, a prior heart attack, congestive heart failure, valve disease or congenital disorders.
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Diagnosing atrial fibrillation
AF can sometimes be diagnosed with a stethoscope during an exam by a doctor or other health care provider and is confirmed or diagnosed with an electrocardiogram (EKG). There are several types of EKG’s. They are:
1. Resting EKG – Electrical activity in the heart is monitored when a person is at rest.
2. Exercise EKG – Activity is monitored when a person jogs on a treadmill or exercises on a stationary bike.
3. 24-hour EKG (Holter Monitor) – A person wears a small, portable monitor that detects activity over the course of a day.
4. Transtelephonic event monitoring – A person wears a monitor for a period of a few days to several weeks. When AF is felt, the person telephones a monitoring station or activates the monitor's memory function. This type of EKG is particularly useful in detecting AF that occurs only once every few days or weeks. Unfortunately this type of monitor does not record heart events while you are sleeping.
The CardioNet Monitor
Your doctor may have you used a CardioNet monitor. This monitor stores 48 hours of continuous data. When it detects an arrhythmia or irregular heartbeat it automatically transmits the EKG to a CardioNet Monitoring Center, where certified cardiac technicians continuously analyze the incoming EKG’s 24 hours a day, 7 days a week. The centers prepare and send reports to the doctor.
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Your medication options
There are three primary goals in the treatment of AF:
1. slow the heart rate
2. prevent clots and strokes, and
3. if possible, restore the heart to its regular rhythm.
Blood-thinning medications, including aspirin and warfarin, may help reduce stroke risk. In fact, long-term use of warfarin has been proven to prevent up to 80% of strokes in people suffering from AF. Aspirin is an option when the risk of stroke is not high. To reduce heart rate, many people can be treated with medications such as digoxin, alone or in combination with beta-blockers and calcium channel blockers, as well as other medications. Your treatment will depend on your age, physical condition and history of heart disease.
Beta-blocker medications
Beta-blocker medications slow the heart rate and decrease how forcefully the heart contracts, reducing the amount of oxygen the heart needs to work. Beta-blockers are often used to treat heart conditions, including high blood pressure, heart failure, fast or irregular heart rates, and mitral valve prolapse, and to help decrease or prevent chest pain. Beta-blockers are also used for migraine headaches, social anxiety disorder, glaucoma, and a common type of movement disorder called essential tremor.
Examples of beta-blockers include:
Acebutolol hydrochloride (Sectral)
Atenolol (Tenormin)
Betaxolol (Kerlone)
Bisoprolol (Zebeta)
Carteolol (Ocupress)
Carvedilol (Coreg)
Esmolol (Brevibloc)
Labetalol (such as Normodyne or Trandate)
Metoprolol (such as Lopressor or Toprol XL)
Nadolol (Corgard)
Penbutolol sulfate (Levatol)
Pindolol (Visken)
Propranolol (Inderal)
Sotalol (Betapace AF)
Timolol (Blocadren)
Calcium channel blockers
Calcium channel blocker medications prevent calcium from entering muscle cells and blood vessels. As a result, blood vessels relax, slowing the heart rate and increasing blood flow to the heart muscle while reducing blood pressure.
Calcium channel blockers are used to treat heart conditions, including high blood pressure, chest pain caused by coronary artery disease, heart failure, and fast or irregular heart rhythms. They are also used to treat severe headaches.
Examples of these medications include:
Amlodipine besylate (Norvasc)
Diltiazem hydrochloride (Cardizem, Dilacor-XR, Tiazac)
Felodipine (Plendil)
Isradipine (DynaCirc)
Nicardipine hydrochloride (Cardene)
Nifedipine (Procardia XL)
Verapamil (Calan SR, Isoptin SR)
Nisoldipine (Sular)
Cardiac glycosides
Cardiac glycosides are medications that can help the heart beat slower and stronger, which helps the heart pump more blood with each beat. Cardiac glycosides are used to treat heart failure and may also be used to treat irregular rapid heartbeats in the upper heart chamber (AF).
Examples of cardiac glycosides include:
Digoxin (such as Lanoxicaps, Lanoxin)
Digitoxin (Crystodigin)
High levels of a cardiac glycoside in the bloodstream can slow the heart rate below normal (bradycardia). This is most likely to occur in people who are receiving medication to help reduce water retention (water pills or diuretics), especially those with decreased kidney function.
Antiarrhythmic medications
Antiarrhythmic medications may be used to return an irregular heartbeat (arrhythmia) to its normal rhythm, prevent the occurrence of an arrhythmia, or control the heartbeat during an arrhythmia. These drugs work mostly by stabilizing the heart muscle tissue or slowing the heart rate.
Examples of antiarrhythmic medications are:
Ibutilide (Corvert)
Amiodarone (such as Cordarone or Pacerone)
Flecainide (Tambocor)
Sotalol (Betapace AF)
Procainamide (Procanbid)
Propafenone (Rythmol)
Quinidine (such as Quinidex)
Disopyramide (Norpace)
Dofetilide (Tikosyn)
Many of these medications have side effects and interactions with other medications. A person taking any of these medications should be in good communication with his or her health professional.
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Restoring the rhythm
To help the heart maintain a normal rhythm, a procedure called cardioversion may be effective. Cardioversion delivers brief electrical shocks that stun the heart and temporarily stop all electric activity. This may allow the normal rhythm to reemerge. However, medication may be required to maintain the normal rhythm and it is not always effective. Cardioversion is used in situations and also may be done electively. Catheter ablation is a method to relieve the rapid, irregular heartbeat that accompanies AF. This procedure involves disconnecting the atria from the ventricles electrically. Without the signals from the atria, the ventricles would beat extremely slowly, requiring a permanent pacemaker in anyone who chooses this procedure.
For some hard-to-treat AF, a surgical procedure that is occasionally performed is the "maze" procedure in which a surgeon divides the atria into small, isolated sections. The chaotic electrical activity of the heart is halted because the electrical impulses cannot cross the scars that separate the sections of the atria. It should only be used for people with severe AF that can't be controlled with medication, or for people undergoing heart surgery for other reasons.
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Catheter Ablation- Pulmonary Vein Ablation (Isolation)
Current PV ablation techniques are achieving partial success rates in curing paroxysmal AF. Medications that did not work before may now control the AF. But for some there may not be any noticeable improvement at all.
During PV ablation a soft, thin, flexible tube with an electrode at the tip is inserted through a large vein or artery in your groin and moved into your heart. This catheter is directed to the precise location(s) in your heart that are producing your AF. These points are burned off or isolated from your heart.
If you are in AF during the catheter ablation procedure, it's relatively easy for the doctors to determine where the A-Fib signals are coming from and to ablate (destroy) them.
However, if you have intermittent AF (Paroxysmal AF), it's harder to pinpoint exactly the source(s) of the A-Fib signals. The challenge for doctors is how to locate and eliminate AF signals when the patient is not in AF. Since research has shown that almost all A-Fib signals come from the openings (ostia) of the four pulmonary veins in the left atrium, one technique is to make circular radiofrequency (RF) Ablation lines around each pulmonary vein opening (called "Circumferential" or "Empirical Ablation"). This isolates the pulmonary veins from the rest of the heart and prevents any pulses from these veins from getting into the heart. However, it's difficult to make circular RF lesions and they aren't always successful. This technique can achieve good success rates with for people with paroxysmal AF. For people with chronic AF, success rates may not be as good.
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The "WOLF MINI-MAZE"™
The latest interventional procedure to treat AF is a minimally invasive operation called the "Wolf Mini-Maze." The "Mini-Maze" was developed by Dr. Randall K. Wolf, Professor of Cardiothoracic Surgery and Director of the Center for Surgical Innovation at the University of Cincinnati., using instruments that he helped design. Dr. Wolf's procedure combines an “ablation” method and the "maze" procedure, WITHOUT performing "Open heart surgery." Dr. Wolf developed this new minimally invasive procedure to cure AF without making a 7 inch incision in the sternum or breastbone and without having to use the heart-lung machine. The mini-maze procedure is a much less invasive procedure, in which he enters the heart through small incisions between the patient’s ribs.
Dr. Wolf performs in fact two surgical procedures at one time. He uses a special "bi-polar" RF clamp to ablate and electrically isolate the pulmonary veins, where the triggers are located that activate AF. This ablation procedure is performed through two small “non-rib-spreading” mini-incisions, one on each side of the chest. The word "ablation" simply means to destroy tissue by burning it. This is done in a specific pattern. The chaotic electrical activity of the heart is halted because the electrical impulses cannot cross the burn scars that separate the areas of the atria. The "bi-polar" RF clamp is so efficient that he can perform an ablation in 8 seconds. An ablation would normally take up 3 minutes with a conventional unipolar RF head.
The second part of the procedure is the endoscopic exclusion of the left atrial appendage, a useless “thumb-like” structure of the heart that can host clot formation that can lead to a stroke. Strokes due to AF are particularly devastating.
The devices are navigated by a micro-miniature television camera, so that Dr. Wolf can actually see the heart without opening the chest. The procedures performed at the University of Cincinnati were specifically focused on treating AF as a stand-alone condition. The new less invasive procedure allows patients who have suffered from long-standing intermittent AF to undergo a less invasive surgery to treat their AF and recover faster than traditional surgery for AF. Patients who undergo this procedure are expected to have hospital stays of only 2-3 days, compared to 7 days or more with conventional surgery.