II. Diagnostics: Electrocardiogram
- No history of AV nodal blocking drugs
- No discrete atrial activity
- Discrete P Waves absent
- Atrial Fibrillation waves (F Waves) seen
- Rapid oscillations or fibrillatory waves
- Small irregular waves at rate of 150-300 bpm
- Difficult to detect at high atrial rates (fine)
- Ventricular response
- Rapid rate up to 160-200 bpm
- Irregularly irregular rhythm
- Inconsistent R-R interval
- Variants
- Irregular Wide Complex Tachycardia
- Suggests Atrial Fibrillation with aberrant conduction (Ashman Phenomenon)
- Heart Rate faster than 200/min
- Accessory pathway (e.g. Atrial Fibrillation with Wolff-Parkinson-White or WPW)
- Irregular Wide Complex Tachycardia
III. Differential Diagnosis: Atrial Fibrillation Causes
- Acute coronary ischemia
- Left QRS Axis
- Left P Wave Axis
- Acute Pulmonary Disease
- Mitral Stenosis
- Lone Atrial Fibrillation
- Normal or Left QRS Axis
- Normal or Left P Wave Axis
- Thyrotoxicosis
- Holiday Heart
-
Atrial Flutter
- Prominent saw tooth waves
- Atrial rate slower than Atrial Fibrillation
IV. References
- Casaletto (2014) Crit Dec Emerg Med 28(4): 10-19
- Stiell (2011) Canadian J Cardiol 27(1): 38-46 [PubMed]
- Wann (2011) Circulation 123(1): 104-23 [PubMed]