Overview
Atrial fibrillation is an often insidious condition involving irregular contraction of the ventricles due to fibrillation of the atria. If not properly managed this condition can result in significant complications including cardioembolic stroke.
Classification
- Paroxysmal AF - occurring for <7 days
- Persistent AF - occurring for >7 days
- Permanent AF - long-standing despite attempts at cardioversion
Pathogenesis
Mechanism
- Atrial fibrillation occurs due rapid impulse generation by an ectopic atrial focus, most commonly adjacent to or within the pulmonary vein orifices. Once atrial fibrillation has commenced it is maintained by abnormalities within atrial tissue, such as atrial remodelling.
Causes of Atrial Fibrillation
- Severe acute illness - especially in septic or postoperative patients
- Cardiac - post cardiac surgery, myocardial infarction, valvular disease, cardiomyopathy, congestive cardiac failure, congenital heart disease, Wolff-Parkinson-White
- Cardiovascular risk factors - hypertension, diabetes, obesity
- Pulmonary embolism
- Obstructive sleep apnoea
- Thyrotoxicosis
- Alcohol abuse
Manifestations
Complications of Atrial Fibrillation
- Thromboembolic stroke
- Heart failure
- Syncope
Diagnosis
Diagnostic Tests
- ECG - single ECG or continuous inpatient monitoring
- Holter monitor (24-48 hours)
- External loop recorder
- Implanted loop recorder
ECG Findings
- Ventricular rate 100-180bpm (may be <100 with block or medications)
- Irregular rhythm
- No P waves, with oscillating baseline waves
Management
Management Options
- Rate control - beta blockers, calcium channel blockers, digoxin
- Rhythm control - DC cardioversion, flecainide, sotalol, amiodarone
- Catheter ablation - of the pulmonary vein orifices
- Anticoagulation (to prevent stroke) - warfarin, dabigatran, rivaroxaban, apixaban
Stroke prevention is a major priority in the management of atrial fibrillation, though anticoagulation is not without risks. Clinical calculators such as CHA₂DS₂VASc are used to estimate risk of stroke and assist in deciding whether anticoagulation is necessary.
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