The ECG may simply show sinus rhythm or sinus bradycardia. This is different than a first-degree atrioventricular, or AV, block, which shows a prolonged PR interval. Second-degree sinoatrial exit ...

The ECG criteria to diagnose sinus arrhythmia is a variation of the P-P interval, from one beat to the next, of at least 0.12 seconds, or 120 milliseconds. Sinus arrhythmia ― if not in a young ...