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There are 3 rhythms that are irregularly irregular :
1. Sinus arrhythmia : one P wave morphology and a stable PR interval
2. Multifocal atrial rhythm
= Wandering atrial pacemaker (rate <100 bpm)
or Multifocal atrial tachycardia (MAT) (rate >100 bpm) :
- Multiple ectopic foci within the atria
- Most commonly in seriously ill elderly with severe COPD or CHF
- Typically a transitional rhythm
between frequent APCs to atrial flutter / fibrillation
- MAT during an acute illness is a poor prognostic sign
associated with a 60% in-hospital mortality
- More than 3 forms of P wave morphologies
without any one P wave morphology being dominant
+ Variable PR interval
- Some P waves may be nonconducted; others may be aberrantly conducted
- Mechanism :
Right atrial dilatation (from cor pulmonale)
Increased sympathetic drive
Hypoxia and hypercarbia
Beta-agonists
Theophylline
Electrolyte abnormalities :
Hypokalaemia and hypomagnesaemia (e.g. secondary to diuretics / beta-agonists)
The net result is increased atrial automaticity.
3. Atrial fibrillation : no organized P waves seen
- Haemodynamic instability, cardiomyopathy, cardiac failure, embolic events such as stroke.
- Causes of atrial fibrillation :
Ischaemic heart disease
Hypertension
Valvular heart disease (esp. mitral stenosis / regurgitation)
Acute infections
Electrolyte disturbance (hypokalaemia, hypomagnesaemia)
Thyrotoxicosis
Drugs (e.g. sympathomimetics)
Pulmonary embolus
Pericardial disease
Acid-base disturbance
Pre-excitation syndromes
Cardiomyopathies: dilated, hypertrophic.
Phaeochromocytoma
- Commonly Af ventricular rate : 110 – 160
RVR > 100, SVR < 60
- Causes of slow AF : hypothermia, digoxin toxicity, medications, sinus node dysfunction
- Ashman's Phenomenon : presences of aberrantly conducted beats, usually of RBBB morphology
突然夾雜單一跳 wide QRS, 不是 VPC
Irregular wide QRS :
- Af + bbb
- Af + WPW
- VT / VF
VT - pulse or pulseless
或分成單型性 or 多型性
多型 : TdP ( with QT prolong ) or non TdP
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