Definition and Overview

Atrial fibrillation (also known as a-fib or AF) is one of the many types of arrhythmia, a medical condition that refers to incorrect or irregular electrical sequence of the heart. AF is characterized by irregular and often fast heart rate called quivering.

AF may be paroxysmal, persistent, or permanent. Usually the patient is asymptomatic, and the condition is discovered when tests such as EKG are performed for other cardiovascular-related diseases.

It is a risk factor for stroke since it causes the heart to ineffectively pump blood. The blood pools in the upper atria and creates a clot that blocks the natural flow of blood in the heart and increases blood pressure. It may also lead to chronic fatigue and heart failure.

The symptoms are sometimes similar to a heart attack. AF sometimes goes away even when the symptoms are already quite severe. If it is considered persistent or more long-lasting, certain medications and therapies can help the patient manage the symptoms or restore the normal rhythm.

Causes of the Condition

A-fib doesn’t have a definite cause. Some experience it after they have undergone a cardiac surgery, whether to remove a blockage or to repair a valve. Other health experts consider these as potential causes:

  • Lung disease
  • Obesity and diabetes
  • Certain heart conditions such as hypertrophic cardiomyopathy (a part of the heart muscle becomes thick)
  • Heart attack
  • Atherosclerosis (plaque build-up in the heart’s arteries)
  • Thyroid disorders

To have a more comprehensive understanding of the disease, one must learn how the heart works.

The heart is made up of 4 chambers: two are called ventricles (lower, left and right) and the other two are the atria (upper, left and right).

When blood arrives at the heart, the sinoatrial node (SA node), a cluster of cells found in the right atrium, sends electrical signals from the right atrium to the left atrium to allow the muscles to contract and pump blood toward the ventricles. The signals then travel to the gatekeeper node (atrioventricular node) in the middle of both chambers. The signals may begin to slow down as the ventricles try to fill themselves with blood. From the AV node, the impulses move to the ventricles to allow the chambers to contract and pump blood to various parts of the body including the lungs.

The problem happens when these electrical impulses begin somewhere else other than in the SA node or the signals flow in a disorderly manner. A-fib may also happen when the gatekeeper node cannot control the electrical signals and cause much faster contractions of the ventricles (up to 50 to 75 beats faster than the normal heart rate). Either way, the signals start to fibrillate (quiver) or become disorganized or irregular.

This makes the blood supply irregular as well. If the lungs and other parts of the body don’t receive sufficient or regular amounts of blood, the patient may develop more life-threatening diseases in the future.

Risk factors for a-fib include:

  • Old age (it usually occurs in men and women who are at least 60 years old)
  • family history
  • binge drinking or alcoholism
  • supraventricular tachycardia (SVT), which is common among athletes
  • consistent high blood pressure

Key Symptoms

  • Palpitations (the heart feels like flip-flopping, quivering, or thumping against the chest wall)
  • General weakness
  • Difficulty in breathing
  • Nausea
  • Lightheadedness or dizziness
  • Chest pain
  • Chronic fatigue
  • High blood pressure
  • General weakness
  • Fainting spells
  • Excessive sweating
  • Cold hands
  • Chest pressure

Who to See and Treatments Available

Often, patients don’t know they have AF unless they have undergone a routine or special diagnostic exam for another disease. If the doctor (who may be a cardiologist or an electrophysiologist, who specializes in arrhythmia) suspects a-fib, he may recommend any or some of the following tests:

  • EKG (electrocardiogram), a device that detects and records electrical signal activities of the heart
  • Chest X-ray to see the general condition of the lungs and heart
  • Blood tests to rule out other diseases such as thyroid disorders and diabetes, as well as to monitor levels of blood oxygen and electrolytes
  • Echocardiogram that obtains an image of the heart using sound waves
  • Transesophageal echocardiography (TEE), which creates an image of the atria using sound waves
  • Stress test where the patient is asked to run on a treadmill with incline and speed settings adjusted; the patient is connected to an EKG to monitor the level of stress that can be handled by the heart

Since the symptoms sometimes go away during the day, the doctor may also instruct the patient to wear a Holter monitor that counts heartbeats within 24 hours or longer.

AF may be classified into three. If the symptoms last for only a few minutes and come and go during the day, it is considered occasional AF (paroxysmal).

If the rhythm cannot be restored without any intervention (usually the symptoms last for seven days or more), the condition is considered persistent. If the medications and other treatments are more long lasting, the a-fib may be permanent. Doctors may no longer try to restore the correct or normal rhythm if the a-fib is permanent.

Usually, doctors recommend medications as the first line of treatment. These are meant to control the heart rate (beta blockers such as Metroprolol or cardiac glycosides like Lanoxin), restore the heart’s rhythm (e.g., Betapace or Pacerone), or prevent blood clot (e.g., warfarin).

If none of these medications are helpful or if the condition is already severe, the doctor may then recommend MAZE procedures such as Cox and mini MAZE. In general, MAZE involves making incisions into the atria to force them to produce scar tissues. These tissues cannot receive electrical signals and thus prevent erratic electric impulses from happening.

Another option is catheter ablation, which is less invasive than MAZE. Thin catheters are inserted into the blood vessels found in the groin, arms, or neck. The blood vessels then lead these flexible wires into the heart. Once they reach the heart, the doctor applies RF (radiofrequency) energy into the organ to destroy some tissues and encourage the formation of scars.

A person with a-fib may still exercise as long as it doesn’t lead to more severe symptoms of the disease.

Resources:

  • http://www.nhlbi.nih.gov
  • http://www.heart.org
  • http://www.stopafib.org/
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