Reviewed by DR. D. DATTA.
Ex. Emergency Medical Officer.
Atrial fibrillation is a heart (cardiac) disease and the commonest sustained cardiac arrhythmia.
Discover everything about Atrial Fibrillation (AFib)—its causes, symptoms, risk factors, diagnosis, treatment options, lifestyle management, and prevention. Learn how to manage AFib effectively and when to seek medical help.
[Normal heart beats in a normal (sinus) rhythm. In cardiac arrhythmia this normal rhythm of heart beat is lost. Normal electrical system of heart Read more
Mechanism of atrial fibrillation
In normal sinus rhythm, the electrical Impulse of the heart starts at the SA node ( Sino-Atrial node) situated in the right Atrium. But in some conditions such as atrial fibrillation certain heart tissues other than SA node becomes capable of initiating electrical impulse of heart. These impulses originate from different sites are chaotic, irregular, rapid (atria may beat at a rate of 400 or more) and uncoordinated therefore causing weak, rapid and irregular atrial contractions.
As the force of contraction is weak, blood cannot be expelled properly to ventricles from atria and there is stagnation of blood in atria. These impulses reach AV node, but the AV node cannot conduct all these impulses to ventricles and the ventricles usually beats at the rate of 120- 180 beats/minute and beats are irregularly irregular, although in Some cases, it may beat at a rate of < 100 beats/ minute (slow atrial fibrillation) or even more than 200 beats/ minute.
Mechanism how atrial fibrillation originates and sustained is not well understood. Pulmonary veins, four in number, two superior and two inferior situated in the left atrium play an important role in atrial fibrillation. Left atrial musculature extends from the left Atrium to envelope the proximal part of the pulmonary veins. Enhanced automaticity and triggered firing from these muscles initiate atrial fibrillation. Reentry at Pulmonary vein and Pulmonary vein-left atrial Junction is potentially an important driver of atrial fibrillation.
The incidence of atrial fibrillation increases with age and occurs in 5 – 10 % of the population above 70 years.
It is rare in children in absence of structural heart disease or other pre-existing arrhythmia that may lead to atrial fibrillation.
Globally, millions of people live with AFib. According to the American Heart Association (AHA), the condition affects approximately 1 in 4 adults over the age of 40 at some point in their lives. Early diagnosis and proper management are crucial to prevent serious complications.
Causes of atrial fibrillation
1 Coronary artery disease including myocardial infarction
2 Valvular heart disease mainly mitral stenosis
3 Hypertension
4 May Be triggered by other S.V.T (supraventricular tachycardia) (such as AVNRT)
5 Sick sinus syndrome
6 Congenital heart disease such as persistent atrial septal defect
7 Cardiomyopathy
8 Pericardial disease, myocarditis
9 Congestive heart disease
10 Lung diseases such as pneumonia, emphysema, COPD ( chronic obstructive pulmonary disease)
11 Pulmonary embolism
12 Viral infection
13 Hyperthyroidism and Hypothyroidism- sometimes atrial fibrillation may be the only sign of hyperthyroidism.
14 Exposure to stimulus – alcohol particularly in excess amount (binge drinking), caffeine, amphetamine, cocaine.
15 During acute or early recovery from major vascular, abdominal and thoracic surgery
16 Sleep apnea
17 Pheochromocytoma
18 Sepsis
19 Electrolyte imbalance
20 Idiopathic (where cause is unknown)- lone atrial fibrillation ( causes 30-40 % Of Paroxysmal atrial fibrillation and 20-30% of persistent atrial fibrillation).
Risk Factors
Several factors increase the likelihood of developing AFib:
- Age: Risk increases after 60 years
- High blood pressure
- Obesity and metabolic syndrome
- Diabetes mellitus
- Chronic kidney disease
- Smoking and alcohol use
- Family history of AFib
- Sleep apnea
- Excessive endurance exercise
- Thyroid imbalances
Managing these risk factors can significantly reduce the chance of developing AFib.
Symptoms of atrial fibrillation
1 Some patients with atrial fibrillation are asymptomatic. In these patients atrial fibrillation is diagnosed when they are examined by a doctor clinically or some investigations such as ECG (Electrocardiogram) done for some other reason.
2 Palpitation- onset of atrial fibrillation may be felt as palpitation, sensation of irregular heartbeat.
3 Heart failure
4 Weakness
5 Light headedness
6 Dizziness
7 Syncope
8 Chest pain
9 Shortness of breath
10 Fatigue
11 Exercise intolerance
12 Due to ineffective left atrial contraction, left atrial dilatation, stasis of blood may lead to clot formation and there is risk of systemic thromboembolism (a blood clot obstruct a blood vessel after it dislodged from it’s site of origin) and its consequences.
When to See a Doctor
You should see a doctor immediately if:
- You experience chest pain, severe shortness of breath, or fainting.
- You notice frequent or worsening palpitations.
- You have known heart disease, diabetes, hypertension, or thyroid problems and begin experiencing irregular heartbeats.
Early intervention can prevent complications like stroke or heart failure.
Types of atrial fibrillation
Atrial fibrillation can be categorized by the
(A) presence or absence of problem within heart valves ( Valvular and non valvular atrial fibrillation )
(B) duration of atrial fibrillation [ Paroxysmal, Persistent, Long-standing persistent and Permanent (Chronic) atrial fibrillation.]
Valvular atrial fibrillation– When the cause of atrial fibrillation is a heart valve whether it is artificial or a natural valve with a disease such as stenosis (stiffening) or there is regurgitation (reverse flow) of blood due to improper closing of that valve it is called valvular atrial fibrillation.
Non-valvular atrial fibrillation– When the cause of atrial fibrillation is not associated with a heart valve and it is caused by certain other reasons, sometimes the cause may be unknown.
Paroxysmal atrial fibrillation– When the episode of atrial fibrillation lasts less than one week it is called Paroxysmal atrial fibrillation. It is episodic and sometimes may be triggered by certain incidences such as heavy drinking, under extreme stress etc.
It may last from a few minutes to a few days. There may or may not be any symptom and the arrhythmia may resolve without any treatment.
Persistent atrial fibrillation– When atrial fibrillation persists at least one week it is called Persistent atrial fibrillation.
Long-standing persistent atrial fibrillation– when atrial fibrillation continues more than one year without any interruption it is called Long-standing persistent atrial fibrillation. Medications usually fail to resolve the condition and invasive treatment like electrical cardioversion/ catheter ablation/ pacemaker implantation is necessary in addition to medical management.
Permanent(Chronic) atrial fibrillation– When all modalities of treatment fail to resolve an atrial fibrillation it is called Permanent atrial fibrillation. In this situation drugs to lower heart rate and to prevent blood clot formation are used. Heart remains in a state of atrial fibrillation all the time.
Complications of Atrial Fibrillation
If left untreated, AFib can lead to serious complications, including:
- Stroke:
Blood clots formed in the atria can travel to the brain, causing ischemic stroke. People with AFib are 5 times more likely to suffer a stroke. - Heart failure:
Inefficient pumping weakens the heart over time, leading to heart failure. - Chronic fatigue:
Reduced blood circulation can cause ongoing tiredness. - Cognitive decline:
Repeated episodes of irregular rhythm can affect brain function over time. - Sudden cardiac arrest (rare):
In severe, untreated cases.
Prevention of Atrial Fibrillation
While not all causes can be avoided, the following steps can help reduce the risk:
- Maintain healthy blood pressure and cholesterol levels
- Eat a heart-healthy diet (Mediterranean or DASH diet)
- Engage in regular exercise
- Avoid excessive alcohol, caffeine, and smoking
- Manage stress through relaxation techniques or yoga
- Treat underlying conditions such as sleep apnea, thyroid disease, or diabetes
- Maintain a healthy weight
Atrial Fibrillation: Diagnosis, Treatment, and Lifestyle Changes
