Atrial fibrillation is the most common arrhythmia. The chances of developing atrial fibrillation increase as a person ages; more than two million Americans have it. Less than one in every 100 people in their 50s has atrial fibrillation, but about 10 in every 100 people in their 80s have it.
Atrial fibrillation is a form of supraventricular tachycardia, in which the heart’s two upper chambers (atria) beat chaotically (fibrillate). They also do not beat in coordination with the two lower chambers of the heart (ventricles). The result is an irregular and often rapid heart rate.
Atrial fibrillation is often caused by changes in the heart that occur with aging or as a result of heart disease. It may occur sporadically or may be a chronic condition. Although it is not life threatening, atrial fibrillation can lead to complications such as stroke and congestive heart failure.
Causes of Atrial Fibrillation
A patient who has atrial fibrillation, he or she does not necessarily have blockages in the arteries serving the heart muscle (the coronary arteries), and does not necessarily have other serious heart problems. However, most people who have atrial fibrillation have other heart disease, such as:
- Long-term high blood pressure (hypertension)
- Abnormalities of the heart valves (thin tissue flaps that keep blood flowing in one direction through the heart)
- Abnormalities of the heart’s pumping function
But, structural heart disease cannot be identified in about one-third of people with atrial fibrillation, for whom the cause is unknown. Possible causes of their atrial fibrillation include:
- Microscopic abnormalities of the muscle of the atria
- Abnormalities within individual heart cells
- Abnormal electrical properties of groups of heart cells
- Exposure to heart irritants such as alcoholic beverages, caffeine or too much thyroid hormone
Effects of Atrial Fibrillation
While atrial fibrillation itself is not life threatening, potentially serious problems may develop, such as blood clots, heart muscle weakness and quality-of-life changes.
The most pressing problem is the formation of blood clots, or thrombi, within the atria. When the muscular walls of the atria quiver instead of contracting forcefully, they are more likely to let blood clots form. If a blood clot breaks free, travels to the brain and blocks the blood supply to part of the brain, it may cause a stroke. If a blood clot blocks an artery elsewhere, the part of the body served by the artery may be damaged, whether it is a kidney, an arm or a leg.
People who have atrial fibrillation and are most likely to form blood clots have the following risk factors:
- Over 65 years old
- High blood pressure
- A previous stroke
- Atrial enlargement
- Weakened ventricle or heart failure
- Heart-valve abnormalities or heart-valve replacement surgery
- Other structural abnormalities of the heart
People who have these risk factors have an increased chance of having a stroke that ranges from 1 to 15 percent each year. This risk may be reduced by anticoagulant medications, called “blood thinners,” to prevent clot formation. Warfarin (Coumadin) is needed to prevent blood clots in many cases. At the heartbeat clinic we have the capability to perform finger-stick tests for anticoagulation levels. We also closely follow warfarin levels by computer based programs.
Atrial fibrillation causes a second problem known as cardiomyopathy, which is when the heart muscles starts to weaken. Specifically, if atrial fibrillation causes the ventricles to beat rapidly (called tachycardia) for a long time, the muscle of the ventricles may fatigue and weaken. The problem becomes more serious if the patient has other heart disease. The time to tachycardia-induced cardiomyopathy may be several weeks to months. However, it doesn’t happen in hours or usually even days.
Even without other heart disease, rapid heart rates may lead to heart failure with these symptoms: shortness of breath, weakness, fatigue and exercise intolerance (tiring easily with activity).
Cardiomyopathy occurs in less than one in every five people who have long-term atrial fibrillation. The risk of developing cardiomyopathy, however, stresses the importance of using medication to slow the electrical impulses traveling from the atria to the ventricles.
While most people who have atrial fibrillation do not develop blood clots or cardiomyopathy, their lives may be affected by palpitations (uncomfortable sensations of the heartbeat in the chest), fatigue, exercise intolerance and shortness of breath. These symptoms may be caused by a fast, irregular heart rate or by a combination of electrical abnormalities, loss of atrial contraction and a weakened pumping ability of the heart’s main pumping chamber (the left ventricle).
Most people who have atrial fibrillation need more than one type of treatment. For example, some people benefit from using medications along with atrial pacing or catheter ablation. Others benefit from using several types of partially effective treatments. A treatment strategy that works for one person may not work for another because each person is unique. Careful evaluation by a physician is required to determine the proper treatment strategy for each patient
Treatments for atrial fibrillation may include medications, surgical procedures and medical devices that help the heart beat easier. The goals of treatment include restoring the heart to normal rhythm, slowing the heart rate and preventing blood clots.
When atrial fibrillation cannot be stopped, the goal is to slow the heart rate. Traditionally, doctors have prescribed digoxin. This medication may control heart rate at rest, but not as well during activity. A newer approach is to use calcium channel blockers or beta-blockers. These control heart rate more consistently both at rest and during activity. The anti rhythm medications have various life threatening side effects and a very narrow therapeutic window. At the heartbeat clinic we have developed point of care testing for most of the tests required to follow rhythm medications. We are the only practice in metroplex with these types of arrangements. We follow our patients with our proprietary, custom made, follow up computer a program that tracks abnormal test results and warns us of any abnormalities and abnormal trends.
To correct atrial fibrillation — reset the heart to its regular rhythm (sinus rhythm) — physicians often perform a procedure called cardioversion. This can be done in two ways:
Cardioversion with medication
Medications called antiarrhythmics are used to stop the atria’s quivering and restore normal sinus rhythm. The medications effectively maintain sinus rhythm for at least one year in 50 to 65 percent of people. However, they can cause side effects such as nausea and fatigue, as well as some long-term risks. In rare cases, the medications may actually increase the heart rate.
In this procedure, a patient under light anesthesia receives an electrical shock through paddles or patches on the chest. The shock stops the heart’s electrical activity for a split second. When the electrical activity begins again, it may resume normal rhythm.
Cardioversion is not always effective. It may successfully restore regular heart rhythm in over 95 percent of patients, but more than half of those people eventually go back into atrial fibrillation. In many instances, antiarrhythmic medications are needed indefinitely.
Pulmonary vein isolation ablation (PVI Ablation or PVA)
This procedure electrically isolates “hot spots” in the pulmonary veins that start atrial fibrillations. It eliminates atrial fibrillation in 60 percent of patients who are treated. In addition, medications that did not help patients prior to ablation are now effective. The complication rates are in the range of 2-4 %. Major complications include perforation of heart, stroke, bleeding, hemorrhage and death.
Catheter Maze Procedure
Physicians who treat arrhythmia have attempted to replicate, through ablation, the lines of scar tissue created through the open-heart maze procedure. Success rates for this procedure depend on what part of the heart is involved in the procedure.
- Left atrial catheter maze procedure has a success rate of 50 to 75 percent.
- Right atrial catheter maze procedure has a success rate of 10 to 15 percent. This is also known as RALA (Right atrial linear ablation). The complication rates are 0-1%. For 40 to 60 percent of patients, control of the atrial fibrillation may be possible if medications are continued after the ablation.
AV node ablation with pacemakers
The upper and lower chamber of the heart are connected electrically bt a relay station called AV node. The rapid fast signals from the atrium (upper chamber) are conducted to ventricles (lower chambers) via this AV node. This procedure involves applying radiofrequency energy to the atrioventricular (AV) node through a catheter to destroy a small area of tissue. This prevents the atria from sending too many electrical impulses to the ventricles. The atria continue to fibrillate and anticoagulation medication is still required. In 98 percent of patients, this procedure causes a complete block of the heart’s electrical impulses. A pacemaker is then implanted to establish normal rhythm.
In a study, 85 percent of people who had this procedure reported an improved quality of life and increased ability to exercise. The success rate is 99 %, complication rates are 1%. However it a palliative procedure only and leaves patient dependant on permanent pacemaker.
A pacemaker is a medical device that helps regulate the heartbeat. The device, smaller than a matchbox, is placed under the skin near the collarbone. A wire extends from the device to the heart. If a pacemaker detects a heart rate that is too slow or no heartbeat at all, it emits electrical impulses that stimulate the heart to speed up or start beating again.
A pacemaker is used most often for patients in one of two situations:
- If medications used to prevent atrial fibrillation or control the rate lead to excessively slow heartbeats
- After AV node ablation
For people with occasional fibrillation, new types of pacemakers may help prevent recurrences. There is some data that the pacemakers if positioned in the atrial septum (midline) may work better than conventional placement. At The Heartbeat clinic we are proficient in all locations of pacemaker placement.
Surgical techniques developed during the 1990s have been used to cure atrial fibrillation. For surgical maze procedures, surgeons create multiple cuts into the muscle of the atria and then stitch them together. These incision lines interfere with stray electrical pathways and circuits. The lines reduce the size of atrial tissue sections needed to maintain atrial fibrillation.
This open heart surgery technique eliminates atrial fibrillation in 80 to 90 percent of those who undergo this surgery. Even those who do not respond as well may have more success with drug therapy after the procedure than they had before the procedure.
Minimal Access Maze Procedure
New technologies are emerging to make the maze procedure faster, safer and less invasive. We work closely with surgeons who are now able to create electrical barriers in the wall of the heart. Using this procedure, electrical activity is permanently blocked. Electrical barriers can be created in 60-90 seconds, minimizing the time it takes to perform the procedure. Some patients may be candidates for new alternative techniques that use radiofrequency or microwave energy, reducing the number of incisions made in the heart.
Heart surgeons are sometimes able to use a minimal access technique in which a catheter is inserted through a small incision outside the heart. Instead of a scalpel, a radiofrequency device is used to create the lesions on the atria. Dr. Suleman help the surgeons to perform intra-operative mapping of atrial fibrillation. Also see http://www.atrialmaze.com
Advantages of the Maze Procedure
- Corrects atrial fibrillation; many patients require no further treatment
- Restores a regular, coordinated heartbeat brings freedom from long-term use of blood thinners for many patients
- Lowers risk of developing blood clots or strokes
- Decreases symptoms, such as fainting or near-fainting
Candidates for the Maze Procedure
Because the maze procedure involves sophisticated, open heart surgery, it is generally reserved for patients whose atrial fibrillation has not responded well to medications, whose symptoms interfere with their quality of life, and who are at high risk for blood clots or stroke.
Patients who have atrial fibrillation and are already undergoing heart surgery for another condition may benefit from having the maze procedure at the same time. The procedure has been performed in conjunction with coronary artery bypass grafting, mitral valve repair and valve replacement. The procedure typically adds 30-40 minutes to a mitral valve operation, and in conjunction with a mitral valve repair, it may mean freedom from long-term use of blood thinners for many patients.
It is possible for patients who have had previous heart surgery to undergo the maze procedure. The same is true for people who have a pacemaker or have had a previous atrial-ventricular node ablation. The maze procedure is not always feasible after AF ablation. Patients who have had the maze procedure may also need a pacemaker.