ATRIAL FIBRILLATION

What Is Atrial Fibrillation?

Atrial Fibrillation

Atrial fibrillation, also known as A-fib or AF, is one of the most common types of arrhythmias, which are irregular heart rhythms. Atrial fibrillation causes your heart to beat much faster than normal. Also, your heart’s upper and lower chambers do not work together as they should. When this happens, the lower chambers do not fill completely or pump enough blood to your lungs and body. This can make you feel tired or dizzy, or you may feel like your heart is skipping a beat, fluttering, pounding, or beating too hard or fast. You may also feel chest pain. Blood may pool in your heart, which increases your risk of forming clots and can lead to strokes or other complications. Atrial fibrillation can also occur without any symptoms. Untreated atrial fibrillation can lead to serious and even life-threatening complications.

Types

Paroxysmal atrial fibrillation: You may experience a brief event — a paroxysm — of atrial fibrillation. It may pass without symptoms, or you may feel it strongly. The event usually stops in less than 24 hours but may last up to a week. Paroxysmal atrial fibrillation can happen more than once and may repeat.

You may need treatment, or your symptoms may go away on their own. When this kind of atrial fibrillation happens and it alternates with a heartbeat that is slower than normal, it is called tachybrady syndrome.

Persistent atrial fibrillation: Persistent atrial fibrillation is when the abnormal heart rhythm you experience lasts for more than a week. It may eventually return to a normal rhythm on its own but probably will need treatment.

Long-term persistent atrial fibrillation: Long-term persistent atrial fibrillation is when abnormal heart rhythms last for more than a year without getting better.

Permanent atrial fibrillation: Sometimes atrial fibrillation does not get better, even when you and your healthcare providers have tried to restore a normal heart rhythm with medicines or other treatments. At this point, your atrial fibrillation is considered permanent.

What causes atrial fibrillation?

When the heart’s tissue or electrical signaling is damaged, the regular pumping of the heart muscle can become fast and irregular. Most often, this type of damage to the heart is caused by other conditions such as high blood pressure and coronary heart disease. However, there are other factors that can also raise your risk for atrial fibrillation.

Typically, the electrical signals that make the heart pump start in the sinoatrial node, a special area of the right atrium, or the upper right chamber of the heart. The signal makes both the right atrium and the left atrium contract. That action pumps blood to the ventricles, or lower chambers. The electrical signal then travels further down the heart, signaling the ventricles to contract. In atrial fibrillation, unusual electrical signals in the upper chambers interrupt the typical process. Then, the upper chambers of the heart do not contract at a regular pace.

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Changes in heart tissue: Aging, heart disease, infection, genetic, or other factors change heart tissue and can keep the heart cells from working together to contract in rhythm. This can happen because of fibrosis, inflammation, thinning or thickening of the heart walls, less blood flow to the heart, or a buildup of protein, cells, or minerals in heart tissue.

Changes in electrical signaling: Usually, a “trigger” heartbeat sets off atrial fibrillation. Electrical signals from this trigger beat may cause the heart to keep beating slower or faster than usual. Sometimes, electrical signals start an abnormal loop, telling the heart to contract over and over. This can create the fast, irregular heartbeat that defines atrial fibrillation.

Changes in the heart’s electrical signaling can be caused by differences in the structure of the heart, heartbeats that happen early or too often, typical heart rate adjustments, patches of heart tissue that conduct the signal quickly or slowly, or repeated stimulation of specific areas of the heart.

What raises the risk of atrial fibrillation?

Age, family history and genetics, lifestyle, heart disease or other medical conditions, race, and a surgical history can all raise your risk of developing the structural and electrical issues that lead to atrial fibrillation. Even in a healthy heart, a fast or slow heart rate — from exercising or sleeping, for example — can trigger atrial fibrillation.

Age: The risk of atrial fibrillation increases as you age, especially after age 65. Atrial fibrillation is rare in children, but it does occur, especially in boys and in children who have obesity.

Family history and genetics: If someone in your family has had atrial fibrillation, you have a higher risk of developing atrial fibrillation, too. Scientists have found some genes with mutation that raise the risk of atrial fibrillation. Some of these genes influence fetal organ development or heart cell ion channels.

Sometimes these genetic patterns are also linked to heart disease. Some genetic factors may raise the risk of atrial fibrillation in combination with such factors as age, weight, or sex.

Lifestyle factors: Some lifestyle choices can raise or lower your risk of atrial fibrillation.

  • Alcohol consumption in large amounts, especially binge drinking, raises your risk of atrial fibrillation. Even modest amounts of alcohol can trigger atrial fibrillation in some people.
  • Illegal drugs, such as cocaine and other street drugs, can trigger atrial fibrillation or make it worse.
  • Physical activity, for example, participating in endurance sports or physically working hard, may lead to higher risk of atrial fibrillation for some people, especially competitive athletes and men. At the same time, moderate physical activity can have a protective effect. Physical fitness appears to be linked to a lower risk of atrial fibrillation.
  • Smoking increases the risk of atrial fibrillation, according to many studies. The risk appears to be higher the longer you smoke and decreases if you quit. Exposure to secondhand smoke, even in the womb, can increase a child’s risk of developing atrial fibrillation.
  • Stressful situations, panic disorders, and other types of emotional stress may be linked to a higher risk of atrial fibrillation.

Other medical conditions: Many other medical conditions can increase your risk of atrial fibrillation, especially heart problems. As you age, having more than one condition may increase your risk. Conditions that raise the risk of atrial fibrillation include:

  • Chronic kidney disease
  • Conduction disorders
  • Congenital heart defects
  • Coronary heart disease
  • Diabetes
  • Heart attack
  • Heart failure
  • Heart inflammation
  • Heart tissue that is too thick or stiff
  • Heart valve diseases
  • High blood pressure
  • Hyperthyroidism, an overactive thyroid gland
  • Lung diseases, including COPD
  • Obesity
  • Sarcoidosis
  • Sleep apnea

Race: In the United States, atrial fibrillation is more common among white Americans than among African Americans, Hispanic Americans, or Asian Americans. Although people of European ancestry are more likely to develop the condition, Black and African American people with atrial fibrillation are more likely to have serious complications such as stroke, heart failure, or heart disease where blood flow (and oxygen flow) is reduced.

Surgery: You may be at risk of atrial fibrillation in the early days and weeks after surgery on your heart, lungs, or esophagus. Heart surgery to correct a congenital heart defect can also raise the risk of atrial fibrillation. This risk remains even years after a childhood surgery. It is also a risk if someone has surgery as an adult to correct a lifelong condition.

Treatment

Your doctor may consider treating your atrial fibrillation with medicines to slow your heart rate or to make your heart’s rhythm more even.

  • Beta blockers, such as metoprolol, carvedilol, and atenolol, help slow the rate at which the heart’s lower chambers pump blood throughout the body. Rate control is important because it allows the ventricles enough time to fill with blood completely. With this approach, the abnormal heart rhythm continues, but you may feel better and have fewer symptoms. Beta blockers are usually taken by mouth, but they may be delivered through a tube in an emergency. If the dose is too high, the heart may beat too slowly. These medicines can also make COPD and arrhythmia worse. Some people with low blood pressure cannot take beta blockers because they also lower blood pressure.
  • Blood thinners like edoxaban, dabigatran, warfarin, heparin, and clopidogrel prevent blood clots and lower the risk of stroke. You may not need to take blood thinners if you are not at risk of a stroke. Blood-thinning medicines carry a risk of bleeding. Other side effects include indigestion and heart attack.
  • Calcium channel blockers including diltiazem and verapamil control the rate at which the heart’s lower chambers pump blood throughout the body. 
  • Digitalis, or digoxin, controls the rate blood is pumped throughout the body. It should be used with caution, as its use can lead to other arrhythmias.
  • Other heart rhythm medicines slow a heart that is beating too fast or change an abnormal heart rhythm to a normal, steady rhythm. Rhythm control is an approach recommended for people who continue to have symptoms or otherwise are not getting better with medicines that control heart rate. Rhythm control also may be used for people who have only recently started having atrial fibrillation or for highly physically active people and athletes. These medicines may be used alone or in combination with electrical cardioversion. Your provider may prescribe some of these medicines for you to take as needed when you feel symptoms of atrial fibrillation. Some heart rhythm medicines can make arrhythmia worse. Other side effects include low blood pressure, indigestion, and effects on the liver, lungs, and other organs.

Procedures or surgery: Your provider may recommend a procedure, especially if lifestyle changes and medicine alone do not improve your symptoms. Typically, your doctor will consider a surgical procedure to treat your atrial fibrillation only if you will be having surgery to treat some other heart condition.

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  • Electrical cardioversion restores your heart rhythm using low-energy shocks to your heart. This may be done in an emergency or if medicines have not worked.
  • A pacemaker reduces atrial fibrillation when it is triggered by a slow heartbeat. Typically, a pacemaker is used to treat atrial fibrillation only when it is diagnosed along with another arrhythmia such as a slow heart rate or sick sinus syndrome. If you have surgery to receive a pacemaker, you will also need to take blood-thinning medicines.
  • Catheter ablation destroys the tissue that is causing the arrhythmia. Ablation is not always successful and in rare cases may lead to serious complications, such as stroke. The risk that atrial fibrillation will reoccur is highest in the first few weeks after the procedure. If this happens, your doctor may repeat the procedure. In some cases, you may have a pacemaker placed at the time of the procedure to make sure your heart beats correctly once the tissue causing problems is destroyed.
  • Surgical ablation destroys the damaged heart tissue that is generating faulty electrical signals. The doctor usually performs surgical ablation at the same time as a surgery to repair heart valves, but in some cases, surgical ablation can be done on its own.
  • Plugging, closing, or cutting off the left atrial appendage prevents clots from forming in the area and causing a stroke if you cannot take blood thinners. Your doctor may do this at the same time as surgical ablation. It can be difficult to close off the appendage entirely, and any leaking contributes to ongoing clotting risk.

Source: https://www.nhlbi.nih.gov/health/atrial-fibrillation

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