Norfolk County Cardiologist Association
Beating the Odds...
Our guide to living with atrial fibrillation, a key stroke risk factor.
Your heart and how it contracts
Your heart is an amazingly coordinated system of muscle and electricity. It has four chambers. The two top ones are the atria. They receive blood from the body. The two bottom ones are the ventricles. They pump blood to the body.
Certain heart cells in the right atrium called the heart's pacemaker generate an electrical signal that causes the heart to beat. The electrical signal spreads through the atria first and causes them to contract and empty blood into the ventricles. Then the signal passes into the ventricles. They contract and the heart pumps blood rhythmically throughout your body. These signals keep your heart beating and pumping blood that contains food and oxygen. These electrical signals go on all day, all night, all your life.
That's why timing is everything. The heart usually beats regularly about 70 to 80 times a minute. Sometimes your heart's electrical signals can lose their regular pattern. In the condition called atrial fibrillation (AF), many parts of the atria start emitting electrical signals in an uncoordinated manner. The atria pump too fast and unevenly and won't fully contract. In fact, they may contract 5-7 times faster than normal - as high as 300-400 beats per minute. Not all these signals go to the ventricles, so although their rate is irregular, it won't be this fast, and the ventricles can still pump out blood.
Although AF itself isn't life-threatening, it can lead to other rhythm problems, chronic fatigue, congestive heart failure and - worse of all - stroke. That's why, after being diagnosed with AF, you'll want to start working with your doctor right away. Because timing is everything.
Atrial Fibrillation and Stroke Risk
When your left atrium pumps too fast and unevenly, blood doesn't empty completely into your left ventricle. Instead, leftover blood "pools" in the atrium.
This blood can form clots. If a clot breaks lose, enters the bloodstream and travels to the brain, it can plug an artery and cause a stroke. This doesn't happen to everyone with AF, but your chances of having a stroke are five times higher if you have AF. About 15 percent of all strokes occur in people with AF. That's about 90,000 cases a year in the United States.
Left untreated, the overactive heart muscle can weaken and stretch out. This makes it harder for the atria to contract properly, so blood backs up even more. This problem not only increases your risk of stroke, but it can lead to congestive heart failure, too.
Symptoms of AF
Some people with AF don't feel a thing. Others notice an irregularity immediately. If you have AF, you may have had sensations that include a racing, uncomfortable, irregular heartbeat and a "flopping" in your chest. Dizziness, sweating and chest pain or pressure also can occur. Other symptoms include difficulty getting your breath, a feeling of overall weakness and being unable to exercise.
Who gets AF and Why?
An estimated 2 million Americans are living with AF. That makes it the most common "serious" heart rhythm abnormality. Certain factors can make you more likely to develop AF, but many times we don't know what causes it.
AF often shows up in people who've had coronary heart disease, heart attack, or heart failure. It's also found in people with heart valve disease, an inflamed heart muscle or lining (endocarditis), or recent heart surgery. People with atherosclerosis (arteries lined with fatty deposits) and angina (chest pain due to reduced blood flow to the heart muscle) sometimes have it. Sometimes it's related to congenital heart defects.
What's more, your heart and lungs work together to keep your blood circulating. That means a problem with your lungs can affect your heart. Not surprisingly, AF often appears in people with chronic lung disease, pulmonary blood clots, emphysema, and asthma.
Gender and age also affect the odds of developing AF and its severity. Men are slightly more likely than women to develop AF, but women diagnosed with it carry a longer-term risk of premature death. Older people are somewhat more likely to have AF than younger people. Other factors that raise risk are thyroid disorders, diabetes, high blood pressure, excessive alcohol intake and cigarette or stimulant drug use (including caffeine!).
That causes of AF include mysteries yet to be solved. But one thing is certain: Careful management reduces risks.
Treatment and Goals
Treating AF correctly is the best way to reduce your stroke risk. Your doctor may prescribe anticlotting drugs such as aspirin or warfarin, or something as involved as surgery. It depends on the underlying cause, your own symptoms and level of disability. But all AF treatment plans should include three goals:
1. Prevent blood clots from forming.
To lower your risk of stroke, your doctor may prescribe either aspirin or warfarin. Both of these drugs interfere with your blood's clotting ability. Aspirin has an antiplatelet effect. That means it makes your blood platelets less likely to stick together and form clots. Aspirin is less likely to cause abnormal bleeding, but warfarin seems to be more effective at preventing clot-causing strokes.
Warfarin is an anticoagluant or blood thinner. That means it reduces your blood's ability to clot (coagulate). Stroke can be prevented in most AF patients by using blood thinners. Most people older than age 60 who have atrial fibrillation can be treated with a blood thinner. These drugs must be very carefully monitored because too much blood thinner can cause abnormal bleeding.
To be sure you're getting the right amount of blood-thinning medication, your doctor will do a test called a Prothromin Time. (This test is also called "Pro-Time" or "PT.") the results of this test may be reported to you an "INR" number. By using an INR, your doctor can keep your blood clotting at a safe and effective level. Your INR should usually test between 2.0 and 3.0.
Tell your doctor right away if you have any unusual bleeding or bruising. If you every forget to take your daily warfarin pill, DON"T take another one to "catch up." Instead, call your doctor, say that you missed your warfarin dose, then follow your doctor's directions. Switching from one form of warfarin to another (such as going from brand to generic versions) can change your PT response, so be extra careful. Even small variations in the amount of the drug you get can cause problems.
Always tell your doctor, dentist and druggist that you take warfarin, especially before you start taking a new medication or have any procedure that can cause bleeding. If you have any problems, tell your doctor right away.
Warfarin can prevent stroke when used as directed, and the risk of stroke is greater than the risk of bleeding if you have AF. Still, it's important to follow your doctor's instructions carefully when you take this (or any) medication.
Both aspirin and warfarin have pluses and minuses. Your doctor will discuss them with you.
Managing your Heart Rate
To control your heart rate, your doctor may prescribe a medication to slow down the rate at which your ventricle contracts. Your ventricles respond to your AF by pumping wildly. That causes the "racing, " "Flopping" feeling in your chest. Controlling this will normalize your heart rate, decrease your heart's workload and reduce your discomfort.
Restoring Proper Rhythm
Sometimes medications such as beta blocker drugs or digitalis may be the best option. There are also interventions available to control or stop the electrical impulses that cause AF. Electrical cardioversion uses a small electrical charge to the heart to "reset" its electrical system. Radiofrequency ablation also uses a catheter, but directs energy at the precise heart tissue area generating the abnormal rhythms. The trouble-making tissue is destroyed and can no longer conduct electricity. Sometimes ablation is used to "disconnect" the entire electrical pathway driving the lower part of the heart. This is done by applying energy to the tissue where all electrical impulses originate (the "sinus note".) in this case you'll need to have a pacemaker permanently implanted to control your heart rate.
These procedures may control your ventricular rate and reduce your symptoms. But your atrium may still pump inefficiently and blood may still pool there. That means you'll still have an ongoing risk of clotting and stroke. To manage this risk, your doctor will keep you on anticoagulants indefinitely.
A final alternative is a surgery called a Maze procedure. With two strategic atrial incisions, it can cure AF by creating scar tissue to block AF's abnormal electrical paths. This surgery is complex but, when successful, it brings two benefits:
1. Your heart chambers will work in proper rhythm with each other again.
Take your Medications
If your doctor has prescribed medication, you must take it exactly as directed. Because your heart is beating all the time, managing your AF requires an even dosage in your system. That's why it's critical to follow orders. Don't take the risk of blood clots and a stroke lightly!
Take Care of Yourself
Another thing you can do is to make healthy lifestyle choices. Ask your doctor for smart eating guidelines; cut back on salt, caffeine, and alcohol; don't smoke; and choose an exercise that you can enjoy and do regularly. For information on these topics, see the list of booklets at the end of this article.
Take it one day at a Time
Finally, remember that researchers continue to investigate ways to cure AF. And they're making progress. The best thing you can do right now is to follow your treatment plan and take things one day at a time.
Your Struggles and Support
You may feel that your family, friends, and employer aren't very understanding. That's common, because your symptoms aren't easily seen by others. It's hard for others to understand how hard it may be for you to function normally while struggling with AF. This emotional pressures, together with the unpredictability of your AF, can make you reluctant to travel, go out or take part in activities you used to enjoy.
It doesn't have to be that way. Your doctor can set up an aggressive treatment plan to control your AF. This will let you continue your life with as few disruptions as possible. You'll want to explain your condition, treatment plan, and any required lifestyle changes to your friends and family. Then they can offer encouragement and support as you adjust to living with AF.
For More Information
For stroke information, call 1-888-4-STROKE (1-888-478-7653) or visit us online at www.StrokeAssociation.org. For information on life after stroke, ask for the Stroke Family Support Network.
To learn more about living a healthy lifestyle, call and request one or more of these booklets from the American Stroke Association and the American Heart Association.
1. Shake Your Salt Habit
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