Atrial Fibrillation (AF, AFib)
Table of Contents
- Atrial fibrillation definition and facts
- What is atrial fibrillation?
- What is the normal function of the heart, and how does its electrical system work?
- What causes atrial fibrillation?
- What are the symptoms of atrial fibrillation?
- How can I know if I am at risk for developing atrial fibrillation?
- How is the diagnosis of atrial fibrillation made?
- What are the treatment guidelines for atrial fibrillation?
- Drugs that slow the heart rate
- Risks and candidates for cardioversion
- Cardioversion with medications
- What is electrical cardioversion?
- Risks and candidates for electrical cardioversion
- Newer medications to prevent stroke
- Procedures for treating and preventing atrial fibrillation
- Other procedures for treating and preventing atrial fibrillation
- What are the complications of atrial fibrillation?
- What is pulmonary vein isolation?
- Who are candidates for PVI, and what are the risks?
Procedures for treating and preventing atrial fibrillation
After successful cardioversion many patients (up to 75%) may experience recurrence of AFib within 12 months. Therefore, many patients will need long-term treatment with medications to prevent a recurrence of the disease; however, medication(s) are effective only 50% to 75% of the time in preventing recurrence. Moreover, many people cannot tolerate the side effects of long-term medication. For these reasons, several procedures have been developed to treat and prevent recurrence of the condition to return the person to good health; they include:
- Ablation of the AV node with implantation of a pacemaker
- Implantation of a pacemaker
- Implantation of an atrial defibrillator
- Maze procedure
Ablation of the AV node with implantation of a pacemaker
Ablation of the AV node is a procedure that destroys the AV node so that the atrial electrical discharges cannot pass through the AV node to activate the ventricles. The procedure usually is performed in a cardiac catheterization unit or an electrophysiology unit of a hospital.
- Procedure: For ablation of the AV node, individuals are given a local anesthetic to minimize pain and are mildly sedated with intravenous medications. Using X-ray guidance, a wire (catheter) is inserted through a vein in the groin to reach the heart. Electrical recordings from inside the heart help to locate the AV node. The AV node is destroyed (ablated) using heat delivered by the catheter. After successful ablation of the AV node, electrical discharges from the atria can no longer reach the ventricles. Destruction of the AV node (whether by catheter ablation or by disease that occurs with age) can lead to an excessively slow rate of ventricular contractions (slow heart rate). Therefore, a pacemaker is implanted in order to provide the heart with a minimum safe heart rate.
- Benefits of ablation of the AV node: The benefits of ablation of the AV node and implantation of a pacemaker include:
- Resumption of a regular heart rate (even though a pacemaker may be determining the heart rate)
- Relief from palpitations, fainting, dizziness, and shortness of breath
- Ability to stop medications and avoid their potentially serious side effects
- Risks of ablation of the AV node: Potential complications of ablation of the AV node and permanent implantation of a pacemaker include bleeding, infection, heart attack, stroke, introduction of air into the space between the lung and chest wall, and death. Still, this technique has helped many patients with severe symptoms to live normally.
- Candidates for ablation of the AV node: Candidates for ablation of the AV node are patients with AF who respond poorly to both chemical and electrical cardioversion. These patients experience repeated relapses of atrial fibrillation, often with rapid rates of ventricular contractions despite medications. Ablation also may be an option for patients who develop serious side effects from the medications that are used for treating and preventing AF.
- Limitations of ablation of the AV node: Ablation of the AV node only controls the rate with which the ventricles beat. It does not convert AF to normal rhythm. Therefore, blood clots still can form in the atria and patients are still at risk for strokes. Thus, there is a need for long-term anticoagulation in addition to the permanent pacemaker.
Other procedures for treating and preventing atrial fibrillation
Permanent pacemakers are battery-operated devices that generate electrical discharges that cause the heart to beat more rapidly when the heart is beating too slowly. Recent studies suggest that some patients with recurrent paroxysmal AFib can benefit from the implantation of a permanent pacemaker. Although the reasons for this benefit are unknown, regular electrical pulses from the pacemakers may prevent the recurrence of AFib. Furthermore, newer pacemakers that can stimulate two different sites within the atria (dual site atrial pacing) may be even more effective than standard pacemakers in preventing AFib. Nevertheless, permanent pacemaker implantation cannot be considered as standard non-medication treatment for atrial fibrillation.
Implantable atrial defibrillators
Implantable atrial defibrillators can detect and convert atrial fibrillation back to a normal rhythm by using high-energy shocks. By detecting atrial fibrillation and terminating it quickly, doctors hope that these devices will prevent recurrences of AFib over the long term.
Atrial defibrillators are surgically implanted within the chest under local anesthesia. These devices deliver high-energy shocks to the heart that are somewhat painful. Atrial defibrillators are not useful in patients with chronic sustained atrial fibrillation and are suitable only for patients with infrequent episodic attacks of AFib.
Many doctors believe that the atria cannot fibrillate if they are sectioned into small pieces so that the conduction of the electrical current through the atria is interrupted. During the Maze procedure, numerous incisions are made in the atria to control the irregular heartbeat and restore a regular rhythm.
- Procedure: The Maze procedure is most commonly performed via open heart surgery. Some electrophysiologists (doctors specially trained to treat abnormalities of rhythm) are now attempting to perform the Maze procedure using catheters inside the heart that are passed through a vein in the groin without open heart surgery. Unfortunately, the success rate using the catheter is below 50% and complications (such as strokes) may occur.
- Effectiveness of the Maze procedure: The Maze procedure done surgically (using open heart surgery) has been reported to correct atrial fibrillation in 90% to 99% of patients. Only 15% to 20% of the patients need a pacemaker after surgery, and there is only a 30% chance of requiring long-term medications to maintain a normal rhythm.
- Risks of the Maze procedure: The surgical Maze procedure involves open heart surgery and the pumping of blood by an external bypass pump while the surgery is performed, much like patients undergoing cardiac bypass surgery. The complications are not insignificant and include stroke, bleeding, infection, and death. Therefore, doctors usually do not recommend a surgical Maze procedure for the treatment of atrial fibrillation unless the patient is undergoing open heart surgery for another condition (such as for coronary artery bypass or replacement or repair of a diseased heart valve).
What are the complications of atrial fibrillation?
- Heart failure: If the heart is unable to pump an adequate amount of blood to the body, as in some people with atrial fibrillation, the body begins to compensate by retaining fluid. This can lead to a condition called heart failure. Heart failure results in the accumulation of fluid in the lower legs (edema) and the lungs (pulmonary edema). Pulmonary edema makes breathing more difficult and reduces the ability of the lung to add oxygen to and remove carbon dioxide from the blood. The levels of oxygen in the blood can drop, and the levels of carbon dioxide in the blood can increase, a complication called respiratory failure. This is a life-threatening complication. In patients with underlying heart disease, the development of AFib may result in up to a 25% decrease in the pumping function of the heart.
- Stroke: Quivering of the atria in atrial fibrillation causes blood inside the atria to stagnate. Stagnant blood tends to form blood clots along the walls of the atria. Sometimes, these blood clots dislodge, pass through the ventricles, and lodge in the brain, lungs, and other parts of the body. This process is called embolization. One common complication of AFib is a blood clot that travels to the brain and causes the sudden onset of one-sided paralysis of the extremities and/or the facial muscles (an embolic stroke). A blood clot that travels to the lungs can cause injury to the lung tissues (pulmonary infarction), and symptoms of chest pain and shortness of breath. When blood clots travel to the body's extremities, cold hands, feet, or legs may occur suddenly because of the lack of blood.
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- Cordarone IV
- Inderal LA
- Lanoxin Tablets
- Procan Sr
- Quinidine Gluconate
- Quinidine Injection
- Rythmol SR
- Tenormin IV Injection
- Toprol XL
- Verelan PM