Atrial Fibrillation (A-Fib): Symptoms, Causes and Risk Factors, Complications, Treatment & Prevention

Atrial Fibrillation

Atrial fibrillation is the most common cardiac arrhythmia. It is a type of arrhythmia that occurs in the upper chambers of the heart called the atria. The heart has 4 chambers, two upper and two lower. The upper chambers receive the blood from the body and pump the blood to the lower chambers (ventricles) and the lower chambers consequently pump the blood to the body. Regular electrical impulses regulate this process, which originate from a small group of heart cells called the sino-atrial (SA) node. These are located in the right atrium.

Once the electric signal generates in the SA node, it passes through both the atria causing them to contract and push the blood collected in them to the ventricles. 

In atrial fibrillation, numerous abnormal electrical impulses occur together, originating in many sites other than the SA node and spreading across the atria. This causes a rippling or fibrillation of the walls of the chambers, but there is no contraction, and the blood is not pumped efficiently into the ventricles. 

Symptoms of Atrial Fibrillation

Patients with atrial fibrillation can have no symptoms. When symptoms occur, they can vary based on the severity of the arrhythmia

  1. Palpitations are the most common symptom. The heart rate can be between 80-150, and sometimes can rise up to 180 beats per minute.
  2. Flutter in the chest
  3. Chest pain
  4. Decreased exercise tolerance
  5. Episodes of dizziness and fainting
  6. Generalised weakness and fatigue

Causes

For some patients with atrial fibrillation, the cause cannot be identified. 

In others, the causes can be varied.

  1. High blood pressure: High blood pressure increases the load on the heart, both on the lower and upper chamber, causing structural alterations and increasing risk of atrial fibrillation
  2. When there are blockages in the arteries that provide blood to the heart, there can rarely be a decrease in oxygen supply to the upper chambers. 
  3. Diseases of the valves that separate the chambers
  4. Inflammation of the heart
  5. Excessive alcohol consumption 
  6. Recreational drug use
  7. Problems in the lung such as pulmonary embolism, cancer, pneumonia
  8. A very high thyroid hormone level

Risk factors of Atrial Fibrillation

  1. Advancing age
  2. Male gender
  3. Sleep apnea
  4. Genetic factors
  5. Congenital heart disease
  6. Congestive heart disease or heart failure
  7. Rheumatic heart disease
  8. Cardiomyopathy
  9. Thyroid disorders
  10. Heart surgery
  11. Chronic obstructive pulmonary disease
  12. Obesity and metabolic syndrome

Diagnosis

Your doctor will be able to identify the change in your heart rhythm when examining your heart using a stethoscope. In atrial fibrillation, the heart beats with an irregularly irregular rhythm. This means that the time between the heartbeats is variable and does not follow a pattern.

  1. Electrocardiogram (ECG): This test measures the electrical activity in the heart and helps confirm the diagnosis of atrial fibrillation
  2. Echocardiogram: This test can be done to find any structural changes that could be the causes of atrial fibrillation like disorders of valves or congenital heart diseases and to find blood clots in the atria that can lead to complications.
  3. Chest X-ray: This is performed to identify any diseases in the lung that can cause atrial fibrillation.
  4. Laboratory tests
    1. Tests for cardiac enzymes such as troponin levels and creatine kinase can be performed to rule out a heart attack as a cause of atrial fibrillation.
    2. B-type natriuretic peptide can be measured to rule out cardiac failure
    3. Thyroid hormone levels can be tested as a very high thyroid hormone level can cause atrial fibrillation
    4. Tests for kidney function and electrolytes can be performed.
  5. Other tests can be suggested by your doctor based on individual analysis of the risk and complications of the arrhythmia

Complications

The major complications of atrial fibrillation occur due to the formation of clots in the upper chambers of the heart.

When the atria do not pump blood adequately due to this arrhythmia, some blood remains in the chamber for longer. As blood has a tendency to clot if it’s not flowing smoothly, this blood clots within the chambers. Over time, parts of this clot can break off and are release into the body and cause blockage of blood flow in different parts of the body, sometimes resulting in stroke when the block occurs in the brain.

Treatment of Atrial Fibrillation

The focus of the treatment of atrial fibrillation is at decreasing the heart rate, maintaining the rhythm and preventing complications due to clots that might have formed in the heart’s upper chambers due to stasis of blood.

  1. Medicines:
    1. Drugs that decrease heart rate: Drugs called beta-blockers or calcium channel blockers can be prescribed. Both of these help in atrial fibrillation by reducing heart rate.
    2. Anti-arrhythmic drugs: These are drugs that maintain heart rhythm, e.g., amiodarone.
    3. Anticoagulants: Based on the patient’s risk for clotting and its complications such as stroke, the doctor might prescribe anticoagulants to decrease the risk of stroke or embolism.
  2. Cardioversion:
    1. This is the process of using drugs or a low energy electrical impulse to restore normal heart rhythm and reverse atrial fibrillation.
    2. Electrical cardioversion: Based on the response to treatment or severity and cause of the atrial fibrillation, cardioversion may be indicated on an emergency or elective basis.
  3. Surgical treatment can be advised in patients who do not respond sufficiently to other modes of treatment.
  4. Others:
    1. Treatment of the underlying cause of atrial fibrillation is very useful.
    2. Lifestyle modifications to improve heart and lung health.
    3. Treatment of sleep apnea
    4. Treatment of thyroid disorders

Prevention of Atrial Fibrillation

  1. As the age-related cardiac disease is one of the risk factors for atrial fibrillation, the same measures that decrease the risk of hypertension and diabetes also help with preventing atrial fibrillation
  2. Lifestyle modifications that include the consumption of a balanced meal coupled with regular moderate-intensity exercise can be a preventative measure
  3. Avoidance of stimulants like cigarette smoking, recreational drugs and excessive alcohol consumption, especially episodes of continuous drinking
  4. Early identification and treatment of heart diseases that can lead to arrhythmias
  5. Early diagnosis and treatment of sleep apnea and endocrine disorders

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