1. Atrial Fibrillation

2. Definition Cardiac output can drop by 10-20%
Chaotic, irregular atrial rhythm at bpm
Maintained by continuous, rapid activation of the atria by multiple meandering re-entry wavelets
Atria respond electrically, but there is no coordinated mechanical action and only a proportion of the impulses are conducted to the ventricles.
AV node responds intermittently, hence irregular ventricular rate
Cardiac output can drop by 10-20%

3. Common in elderly (<9%) Main risk is embolic stroke
Warfarin reduces this to 1%/yr

4. Causes
Heart failure/ischaemia; HT; MI (22%); mitral valve disease; coronary artery disease
PE; Pneumonia; Hyperthyroidism; post-op hypokalaemia; Mg2+ decrease; Phaeochromocytoma
Caffeine; alcohol

5. Symptoms May be asymptomatic or cause- Chest pain Palpitation Dyspnoea
Faintness

6. Signs Irregularly irregular pulse
Apical pulse rate greater than the radial rate
1st heart sound of variable intensity
Should examine whole pt as AF often assoc with non-cardiac disease

7. Investigations ECG: Blood tests: U & E, cardiac enzymes, TFTs (Echo)
Shows fine oscillations of the baseline (fibrillation/f-waves) and absent P waves
QRS rhythm is rapid & irregular
‘Irregularly irregular’
DO an ECG on anyone with irregular pulse (+ 24 hr ECG if dizzy, faints, palpitations etc)
Blood tests: U & E, cardiac enzymes, TFTs
(Echo)
Look for left atrial enlargement, mitral valve disease, poor LV function & other abnormalities

8. Management Acute: Treat assoc illness, control ventricular rate
1st choice: diltiazem or verapamil or metoprolol
2nd rate: digoxin, amiodarone
Start full coag with LMWH
2nd choice: rate control & anticoagulation
Beta-blocker or rate-limiting Ca-blocker
If fails, consider digoxin (as monotherapy) or amiodarone