What is Atrial fibrillation?
Atrial fibrillation (AF) is an arrhythmia where atria beat rapidly, chaotically and ineffectively, while the ventricles respond at irregular intervals, producing the characteristic irregularly irregular pulse.
Types of AF
Atrial fibrillation is of 3 Types—
1. Paroxysmal—Discrete self-limiting episodes. May be persistent, if underlying disease progresses.
2. Persistent—Prolonged episode that can be terminated by electrical or chemical cardioversion.
3. Permanent—Sinus rhythm cannot be restored.
According to heart rate, AF is of 2 types—
1. Fast atrial fibrillation—Heart rate > 100 beats/min.
2. Slow atrial fibrillation—Heart rate < 100 beats/min.
Causes of Atrial Fibrillation:
• Chronic rheumatic heart disease with valvular lesions, commonly mitral stenosis.
• Coronary artery disease (commonly, acute myocardial infarction).
• Thyrotoxicosis.
• Hypertension.
• Lone atrial fibrillation (idiopathic in 10% cases).
• Others—ASD, chronic constrictive pericarditis, acute pericarditis, cardiomyopathy, myocarditis,
sick sinus syndrome, coronary bypass surgery, pneumonia, thoracic surgery, electrolyte
imbalance (hypokalaemia, hyponatraemia), alcohol, pulmonary embolism.
NB: First five causes are always the top most causes.
Complications
• Systemic and pulmonary embolism (systemic from left atrium and pulmonary from right
atrium).
• Heart failure.
Lone Atrial Fibrillation
It means atrial fibrillation without any cause. Prognosis—low risk of CVD (0.5% per year). Usually,
life span is normal.
Clinical Features of AF
Symptoms
• Palpitation, breathlessness, weakness.
Signs
• Pulse—irregularly irregular (irregular in rhythm and volume).
• Examination of heart (heart rate to see pulsus deficit, mitral valvular or other cardiac disease).
• Thyroid status (warm sweaty hands, tremor, tachycardia, exophthalmos, thyroid gland size).
• Check BP in hypertensive case.
Investigations
1. ECG—shows absent P wave (replaced by fibrillary ‘f’ wave) with Irregularly irregular (R-R
interval is irregular).
2. Chest X-ray.
3. Echocardiography.
4. Thyroid function test, if thyrotoxicosis is suspected.
Treatment
Aim of treatment:
• Control of heart rate.
• Restoration of sinus rhythm and prevention of recurrence.
• Treatment of primary cause.
Treatment (according to the type)—
Paroxysmal AF
• If asymptomatic—no treatment, only follow-up.
• In troublesome symptoms—β-blocker.
• Amiodarone is effective in prevention.
• Low dose aspirin to prevent thromboembolism.
• If bradycardia is present (in sinoatrial disease)—Permanent overdrive atrial pacing.
• In intractable cases—Radiofrequency ablation may be required, who does not have structural heart disease.
Persistent AF
• To control heart rate—β-blocker, digoxin or calcium channel blocker (verapamil, diltiazem).
• To control rhythm—DC cardioversion may be done safely.
• β-blocker or amiodarone may be used to prevent recurrence.
Permanent AF
• Control of heart rate—digoxin, β-blocker, calcium channel blocker (verapamil or diltiazem).
• In intractable case—Transvenous radiofrequency ablation may be done, followed by permanent
pacemaker.