Atrial Fibrillation Flashcards
Define
A chaotic, irregular atrial rhythm at 300–600bpm
Rapid, chaotic and ineffective atrial electrical conduction
↘ Permanent, persistent, paroxysmal
Cardiac output drops by 10–20% as the ventricles aren’t primed reliably by the atria
Main risk is embolic stroke (give Warfarin)
Often subdivided into:
Permanent
Persistent
Paroxysmal
Causes
Systemic: hyperthyroidism, HTN, caffeine, alcohol, ↓K+, ↓Mg2+
Heart: MI (seen in 22%), heart failure/ischemia, mitral valve disease, rheumatic heart disease, cardiomyopathy
Lung: PE, pneumonia
Epidemiology
common in elderly (5% of >65 years)
Symptoms
My be asymptomatic
CP, palpitations, dyspnoea, faintness
Signs
Irregularly irregular pulse
1st heart sound of variable intensity
Apical pulse rate is greater than the radial rate
Signs of LVH
Investigations
ECG shows absent P waves, irregular QRS complexes
Uneven baseline (fibrillations)
Bloods → cardiac enzymes, TFT, lipid profile, U&Es, Mg2+, Ca2+
Echocardiogram → to assess for mitral valve disease, LA dilatation, LV dysfunction or structural abnormalities
Management
Treat any reversible causes first
If very ill or haemodynamically unstable → O2, U&Es, emergency cardioversion, start full anticoagulation with Warfarin
Use verapamil or bisoprolol to control ventricular rate
Chronic AF:
(1) RHYTHM CONTROL
*If AF is >48 hours onset, anticoagulated for ~4 weeks before attempting cardioversion, do echo first
DC cardioversion – synchronised DC shock
Chemical cardioversion – flecainide or amiodarone Prophylaxis – Sotalol, amiodarone, flecainide
(2) RATE CONTROL
Chronic permanent AF – ventricular rate control with digoxin, verapamil and/or β blockers
Aim for rate ~90/min
For chronic AF: Rate control is at least as good as rhythm control (but rhythm control may be more suitable in symptomatic younger, presenting for the first time)
Complications
Thromboembolism (embolic stroke4% risk per year) Worsens existing HF
Prognosis
Chronic AF in a diseased heart does not usually return to sinus rhythm
