Atrial Fibrillation - Symptoms, causes & Treatment

What is Atrial Fibrillation?

Atrial fibrillation is described as one of the most common types of arrhythmia characterized by rapid and irregularized atrial contraction which interferes with the normal rhythm of the heart and makes the heart pump ineffectively. Patients with atrial fibrillation may end up experiencing several symptoms such as palpitations, shortness of breath, and fatigue. This condition is also crucial for understanding the physiology of the human body effectively.

Understanding Normal Heart Rhythm

Cardiac excitation begins in the sinoatrial (SA) node. SA node cells do not have a stable resting potential. Rather, they repeatedly depolarize to the threshold spontaneously.

Normal Sinus Rhythm

The usual rhythm of heartbeats, established by the SA node, is called normal sinus rhythm. The term arrhythmia or dysrhythmia refers to an abnormal rhythm as a result of a defect in the conduction system of the heart.

Arrhythmias — Bradycardia, Tachycardia, Fibrillation

Arrhythmias are categorized by their speed, rhythm, and origin of the problem. Bradycardia refers to a slow heart rate, tachycardia refers to a rapid heart rate, and fibrillation refers to rapid, uncoordinated heartbeats.

Symptoms of Atrial Fibrillation

The symptoms of atrial fibrillation vary from person to person. Some common symptoms include:

Palpitations: The sense of a person about his heart racing or fluttering.

Fatigue: Feeling extremely fatigued for a person, especially during trying to do some physical exercise.

Dizziness: Caused mainly by the reduction in blood flow.

Shortness of Breath: Inability to get enough breath to a person especially when lying flat or during attempts to do physical exercises.

Causes of Atrial Fibrillation

Several causes and risk factors may increase the risk of atrial fibrillation for example:

Heart-related Causes

Heart conditions such as hypertension coronary artery diseases and heart valve diseases

Lifestyle-related Causes

Lifestyle factors including excessive alcohol, smoking and obesity.

Other Medical Causes

These include thyroid disorders and respiratory diseases among others

Risk factors of Atrial Fibrillation

Atrial fibrillation reduces the pumping effectiveness of the heart by 20–30%. The most dangerous complication of atrial fibrillation is stroke since blood may stagnate in the atria and form blood clots. A stroke occurs when part of a blood clot occludes an artery supplying the brain. Other risk factors of Atrial Fibrillation include:

• High blood pressure

• Diabetes

• Thyroid (hyperthyroidism)

• Chronic kidney disorders

• Smoking and alcoholic habits

• Variations in the size of heart chambers

• Ancestry (mainly in Europeans)

• Obesity

• Age (in older people)

Types of Atrial Fibrillation

Atrial fibrillation can be classified into various categories, including;

Paroxysmal Atrial Fibrillation

Episodes are recurrent or come and go and spontaneously resolve in less than seven days.

Persistent Atrial Fibrillation

Longer than seven days and may require the initiation of medical therapy to revert back to a normal rhythm.

Chronic Atrial Fibrillation

It is a long-standing condition that is either non-responsive or poorly responsive to any form of therapy

Atrial Fibrillation ECG Features

An atrial fibrillation Electrocardiogram (ECG) is a very important diagnostic tool. The characteristic features of atrial fibrillation ECG are:

• Irregular rhythm

• Absent P waves

• An irregularly irregular ventricular response (QRS complex)

• Rapid atrial rate (300–600 bpm)

Atrial Fibrillation Treatment

The treatment of atrial fibrillation is designed to control symptoms and prevent complications. Common treatments include:

Medications

Anticoagulation therapy with medicines such as warfarin or aspirin to prevent stroke; beta-blockers; and antiarrhythmic drugs to regulate heart rate and rhythm.

Medical Procedures

Electrical cardioversion to restore normal rhythm and catheter ablation to destroy areas of heart tissue that initiate AF.

Atrial Fibrillation vs Atrial Flutter

While both can create abnormal heart rhythms, electrical activity from atrial flutter is often more organized than atrial fibrillation. The rhythm created by atrial flutter often also creates a more regular rhythm and sometimes can be treated like atrial fibrillation.

Atrial Fibrillation with RVR (Rapid Ventricular Response)

In the case of atrial fibrillation with RVR, the heart rate exceeds 100 beats per minute. Such a condition requires immediate management. According to ICD-10, the code for this condition is I48.91.

When It Is an Emergency

AF with RVR becomes an emergency when the heart rate is extremely high, leading to severe palpitations, breathlessness, chest discomfort, or inability of the body to maintain stable blood pressure and circulation, causing poor blood flow to essential organs.

Management Overview

Management focuses on quickly controlling the ventricular rate, stabilizing the patient, and then restoring rhythm or preventing complications using medications, cardioversion, and supportive care.

Atrial Fibrillation NEET MCQs (With Answers & Explanations)

Types of questions asked from this topic are:

• Symptoms & causes of atrial fibrillation

• Types of atrial fibrillation

• Atrial flutter vs atrial fibrillation

Practice Questions for NEET

Q1. Atrial fibrillation is characterized by:

1. Regular atrial contractions

2. Absent P waves and irregular ventricular rhythm

3. Excessive RBC count

4. Blockage of pulmonary artery

Correct answer: 2) Absent P waves and irregular ventricular rhythm

Explanation:

In atrial fibrillation (AF), the atria do not contract in an organized way; instead they quiver due to many rapid, uncoordinated impulses. On an ECG this appears as no distinct P waves (which normally represent atrial depolarization) and an irregularly irregular ventricular rhythm (uneven R–R intervals). Regular atrial contractions are not seen in AF, high RBC count has no direct link, and a pulmonary artery blockage refers to pulmonary embolism, not AF.

Hence, the correct answer is option 2) Absent P waves and irregular ventricular rhythm.

Q2. Which of the following is a risk factor for atrial fibrillation?

1. Hyperthyroidism

2. High WBC count

3. Vitamin C deficiency

4. Pulmonary tuberculosis

Correct answer: 1) Hyperthyroidism

Explanation:

Excess thyroid hormone increases the heart’s metabolic demand and electrical excitability, predisposing to tachyarrhythmias, especially atrial fibrillation. AF risk also rises with age, hypertension, heart disease, obesity, alcohol, and sleep apnea. A high WBC count, vitamin C deficiency, and pulmonary TB are not typical direct risk factors for AF in standard curricula.

Hence, the correct answer is option 1) Hyperthyroidism.

Q3. In atrial fibrillation, the heart pumping becomes inefficient due to:

1. Weak contraction of atria

2. Overactive sinoatrial node

3. Excess blood clotting

4. Strong ventricular contraction

Correct answer: 1) Weak contraction of atria

Explanation:

In AF the atria lose their coordinated “atrial kick,” the small but important push that tops up ventricular filling before each beat. Without this, ventricular filling falls (especially in older adults), so cardiac output drops and patients feel palpitations, breathlessness, or fatigue. AF is usually driven by multiple ectopic foci (often near pulmonary veins), not an overactive SA node; clotting is a complication (blood stasis → atrial thrombi → stroke risk) rather than the cause of pumping inefficiency; and strong ventricular contraction is not characteristic of AF.

Hence, the correct answer is option 1) Weak contraction of atria.

Also Read:

• MCQs on Disorders in the Circulatory System

• Facts about Blood

• Excretory Products and Their Elimination

Recommended Video on Atrial Fibrillation