Diagnostic criteria


  Sinus node cannot depolarize the atrium at the expected time. This results in a long isoelectric line

      between the last QRS complex before exit block and the first P wave coming after the exit block.

  The next sinus P wave comes at a
multiple of the previous PP intervals .

      This feature differentiates SA exit block from sinus arrest.



Causes

  Excessive vagal stimulation

  Miyocardial infarction

  Miyocarditis

  Drugs: Digoxin, Procainamide, Quinidine





ECG 1. Sinoatrial exit block.

Dr. Peter Kukla has donated this ECG to our website.

Click here for a more detailed ECG





ECG 2. Sinoatrial exit block.

Click here for a more detailed ECG