Atrial fibrillation is a commonly encountered rhythm disturbance (arrhythmia) of the heart. In normal persons, the resting heart rate varies between 70 to 100 beats per minute. In atrial fibrillation however], the heart rate can vary from 140 to 180 (upto 400) beats per minute in addition to being irregular in rhythm.

What is atrial fibrillation?
In atrial fibrillation (AF), the two upper chambers of the heart (the atria) contract and relax rapidly in an abnormal fashion, likened to a bowl of quivering gelatin. This rapid rhythm interferes with the normal and effective functioning of the heart and can be associated with serious complications such as clot formation within the heart and stroke.

Types of atrial fibrillation
There are 3 types of atrial fibrillation

• Paroxysmal atrial fibrillation (PAF) – Episodes of AF come and go with normal and rate rhythm in the intervening period which can vary greatly from person to person
• Persistent AF – The atrial fibrillation lasts for more than seven days and will not return to normal without treatment
• Permanent AF – The atrial fibrillation is longstanding and does not return to normal. This could be because of lack of treatment or failed treatment efforts. In these patients, medication may be given to bring down the rapid rate but the rhythm continues to be irregular.

Causes/risk factors of atrial fibrillation
Abnormality in the structure of the heart is the most common cause for atrial fibrillation. Other causes include the following

• High blood pressure
• History of heart attack
• Previous history of heart surgery
• Coronary artery disease
• Diseased heart valves
• Family history of AF
• Obesity
• Heart defects present since birth
• Overactive thyroid gland or other metabolic imbalance
• Intake of stimulants, such as medications, caffeine, tobacco or alcohol
• Sick sinus syndrome — improper functioning of the sinoatrial node (natural pacemaker of the heart)
• Lung disease
• Viral infections
• Sleep apnea
• Stress due to underlying chronic illness

Signs and Symptoms of AF

• Palpitations – ability to feel one’s own rapid heart beat
• Irregularly irregular peripheral pulse (felt at the wrist))
• Chest pain
• Breathlessness
• Tiredness and general weakness
• Confusion
• Dizziness
• Reduced exercise tolerance

Complications of AF
Prolonged untreated atrial fibrillation can lead to

• Stroke – In AF there is increased tendency for blood clots within the heart which may break away and get lodged in the cerebral vessels resulting in stroke

• Heart failure – Untreated AF can weaken the heart and render it unable pump blood to the rest of the body

Diagnosis of AF
Following patient history and physical examination, the following tests may be done to confirm the diagnosis

• Electrocardiogram (ECG) – An ECG uses small sensors (electrodes) attached to chest and limbs to record electrical activity of the heart. An ECG will confirm the diagnosis of atrial fibrillation (if the patient is in AF while the ECG was recorded).

• Holter monitor – When the patient has paroxysmal atrial fibrillation (AF comes and goes) the patient carries a portable ECG device or wears it on the belt or shoulder strap. It records the cardiac activity for 24 hours or longer, and provides the doctor with a more prolonged recording

• Echocardiogram – This test is an ultrasound imaging of the heart using sound waves and will reveal presence of underlying structural defects in the heart

• Chest x-ray – To rule out heart or lung abnormalities

• Blood tests – To rule out specific conditions such as thyroid disease

• Stress test – This is done to see how the heart responds to stress such as exercise

Treatment of atrial fibrillation
Treatment depends on the duration and severity of symptoms and addressing the primary cause. Treatment aims at the following

• Resetting of the rhythm and/or control of the rate
• Prevention of blood clots and reducing stroke risk

MEDICATIONS TO REDUCE HEART RATE
The heart rate in AF is usually between 120 to 160 beats per minute and should be brought down to around 90 beats per minute at rest.

Medications used include beta blockers (such as atenolol and propranolol), calcium-channel blockers (such as diltiazem and verapamil) and digoxin. The choice of drug depends on the cause and presence of other heart conditions that may be present. Sometimes a combination of drugs may
be needed

RESTORING HEART RHYTHM
Cardioversion may be considered in recent onset AF, in patients less than 65 years, if heart is otherwise normal, any underlying cause has been treated, or in the presence of heart failure and unstable angina worsened by the AF. The various methods adopted to control disordered heart rhythm include

• Electric cardioversion – Administering electric shock to the heart to reset the rhythm.

• Cardioversion with drugs – A drug commonly used to restore normal rhythm in AF is amiodarone.

Catheter ablation – In this procedure, a long, thin flexible wire (catheter) is passed via a large blood vessel in a leg and guided into the heart chambers and used to destroy abnormal foci of tissue

Surgical maze procedure – This is done as an open-heart surgery. Doctors create several precise incisions (using a scalpel) in the atria to produce a specific pattern of scar tissue. Since scar tissue does not carry impulses, it blocks stray electrical signals that cause atrial fibrillation.

Radiofrequency or cryotherapy also can be used to produce scars, and there are several variations of this technique.

OTHER TREATMENTS
Treatment of associated conditions such as hypertension, chest pains (angina), heart valve problems, or an overactive thyroid gland (hyperthyroidism) is also indicated.

PREVENTING BLOOD CLOTS
• Blood thinning medications such as warfarin and the newer direct oral anticoagulants are effective in preventing blood clots and the choice of agent depends on patient’s preference and other associated conditions that may be present.

• Left atrial appendage closure surgery may also be considered in some patients

Tips To Maintain Healthy Heart
• Reduce alcohol intake and quit smoking
• Exercise regularly and maintain healthy weight
• Eat a healthy diet rich in fresh fruits and vegetables and whole grains; avoid saturated fats and salt containing foods
• Control of blood pressure and blood sugar levels
• Regular followup with the doctor