Summary ECG and conduction diseases

ECG Conduction diseases and brady-arrhythmia’s


Normal conduction: SA node à AV node à Bundle of His à Purkinje system
Disease at the AV node à AV block (heart block)
Disease in the bundle branches or fascicles
 Bundle branch blocks
 Fascicular blocks


Escape rhythm
 If no impulse arrives
 If the SA node does not fire another area may take over
 The more distal the origin of the escape rhythm the slower the rate
o SA node: 70-80 bpm
o AV node: 40-60 bpm
o Purkinje fibres/ventricles: 15-40 bpm




Beat Type Beat characteristics Example
Sinus  Normal P wave
 Normal (narrow) QRS

Atrial  Abnormal P wave
 Normal (narrow) QRS

Junctional (AV nodal)  P wave absent
(buried in QRS) or;
 Abnormal P wave just
before/after QRS
 Narrow QRS




Ventricular  Wide QRS
 Abnormal T wave
 No P wave

, First degree AV block
 Every P wave is followed by a QRS
 PR Interval >200ms (>1 big square)
 PR interval is constant


Example First degree AV block