Microsoft word - atrialfibrillation.doc

A stroke is one of the most devastating events that an individual can suffer. The revelation that a quarter of the nation’s strokes can be prevented by correctly diagnosing and treating Atrial Fibrillation opened a window of opportunity to save thousands of people from disability each year. Because of this opportunity Atrial Fibrillation has become one of the most intensely studied topics in modern cardiology. It can be caused by many dfferent types of heart disease and frequently occurs in patients without any other form of heart disease. The explanation begins with the atria that are two thin walled relatively weak chambers that collect blood returning to the heart and gently pump the blood into the powerful pumping chambers called the ventricles. Under normal circumstances each atrial contraction fills the ventricle and triggers a ventricular contraction. Both chambers empty in a harmonious sequence. There are several situations in which the atria start beating at a furious tempo, about 600 to 800 times a minute. This is much too fast for the atria to actually open and close efficiently and eject blood quickly. At this rate the atria only have an electrical function transmitting orders to the ventricle. The blood does not flow quickly and tends to pool and swirl in one place for prolonged periods of time before leaving the atria and entering the ventricles. The blood in the rapidly beating or fibrillating atria forms clots because of the pooling and these clots travel into the ventricle and then out of the heart and into important arteries. If the clots land in an artery that supplies the brain, the patient suffers a stroke. About one quarter of this country’s strokes are caused by blood clots that travel to the brain from the Left Atrium of patients with Atrial Fibrillation. This provides an opportunity to prevent these strokes. By treating the patient with anticoagulants such as Heparin or Coumadin the blood clots cannot form even if the blood stands still. These medications are never easy to use. They require expertise and constant measurements to ensure that the dose is adequate. Heparin works immediately but requires an intravenous injection route. Coumadin starts to work after several days but is a pill that is easy to administer. A recent advance is the use of Lovonox injections. The anticoagulation is immediate and the dose necessary is predicted on the basis of the patient’s weight without having to make measurements. Lovonox has two disadvantages. It is administered by injection. Patients without prescription drug coverage find it very expensive. One great advantage is that Atrial Fibrillation patients can now be treated as outpatients without being sent to the hospital. Besides creating a stroke risk the rapidly beating atria cause the ventricles to accelerate and tend to have excessive heart rates. This heart rate acceleration and deceleration is not linked to the body’s needs and can be very inappropriate. There are a small number of patients whose weak hearts depend on the presence of an “atrial kick” to push blood into the heart with each beat. These patients experience symptoms of weakness when they develop Atrial Fibrillation. These situations require treatment for the Atrial Fibrillation itself. There are a large number of medications that can be administered to slow the ventricular rate. The choice of which medication to use is dictated by the patient’s circumstances such as age or pregnancy or the presence of other illnesses that makes one or the other drug inadvisable. There are also medications that can eliminate the atrial fibrillation and restore the heart’s original rhythm. While all cardiologists use these medications at least some of the time. There is great variation between cardiologists about which patients should be treated with these drugs. The source of the controversy is that these drugs tend to have important side effects. Cardiologists tend to save these medications for their sickest patients. It is the trouble defining who is sick enough to warrant these medications that leads to the variation in trament practices between different doctors. When medications fail to control the Ventricular heart rate adequately doctors can administer an electrical shock to the heart. The process is called cardioversion. . This frequently restores the original heart rate and rhythm. This reverses the problems caused by the Atrial Fibrillation. The patients are anesthetized for a few minutes and the procedure is painless. Complications are rarely encountered during these procedures. The cardioversion itself does not eliminate the chance of a blood clot and anticoagulants must be administered fro a few weeks before and a few weeks after the cardioversion. The Maze operation is a surgical procedure that creates small incisions in the atria to eliminate Atrial Fibrillation. This is usually performed in patients who have Atrial Fibrillation and also must undergo a heart operation such a coronary bypass. Although this operation is done infrequently it taught cardiologists a great deal about eliminating Atrial Fibrillation. Now catheters inserted through needle sized holes can use radiofrequency energy to create similar sets of lines that eliminate the aAtrial Fibrillation. It is likely that when this procedure is perfected it will be used commonly to reduce the number of patients depending on Coumadin. There are a large number of patients who have intermittent Atrial Fibrillation. Patients who are able to detect and feel the onset of their Atrial Fibrillation can start and stop their medication at the beginning and after the end of their episodes. Because it takes about twenty four hours for clots to form, these patients time to start Lovonox or Heparin before the clots form. Patients who don’t know when they are in Atrial fibrillation have no choice but to take Coumadin all the time. Their first sign of Atrial Fibrillation could be a stroke when it is too late to start the medication.

Source: http://www.heartdr.com/Articles/AtrialFibrillation.pdf