Atrial Fibrillation

Question 1

What is AF?

Answer 1

A supraventircular arrhythmia characterised by rapid, chaotic depolarisations of the atria. The atrial rhythm is irregular with a rate of 300-600 bpm

Question 2

What are the causes of AF?

Answer 2

• Heart failure/ischaemia
• Hypertension
• MI (seen in 22%)
• PE
• Mitral valve disease
• Pneumonia
• Hyperthyroidism
• Caffeine
• Alcohol
• Post-op
• Low potassium
• Low magnesium
• RARE: cardiomyopathy, constrictive pericarditis, sick sinus syndrome, lung cancer, atrial myxoma, endocarditis, haemochromatosis, sarcoid, lone (no cause)

Question 3

What are the symptoms of AF?

Answer 3

• May be asymptomatic
• Chest pain
• Palpitations
• Dyspnoea
• Faintness

Question 4

What are the signs of AF?

Answer 4

• Irregularly irregular pulse
• Apical pulse rate greater than radial pulse rate, 1st heart sound of variable intensity
• Signs of left ventricular failure

Question 5

What tests can be performed to diagnose AF?

Answer 5

• ECG: shows absent P waves, irregular QRS complexes
• Bloods: U&Es, cardiac enzymes, thyroid function tests
• Echo: to look for left atrial enlargement, mitral valve disease, poor LV function

Question 6

How do you treat acute AF (patient haemodynamically unstable)?

Answer 6

1) 02
2) U&E
3) Emergency cardioversion - if unavailable try IV amiodarone
4) Treat associated illnesses (e.g. pneumonia, MI)
5) Control ventricular rate
- 1st line = Verapamil (40-120mg/8h PO) or Bisoprolol (2.5-5mg/d PO)
- 2nd line = Digoxin or Amiodarone
6) Start full anticoagulation with LMWH to keep options open for cardioversion even if the 48hr time limit is running out - if 48hr time period run out then cardioversion is okay if transoesophageal echo thrombus free