Sinus tachycardia is recognized on an ECG with a normal upright P wave in ... such as in ventricular tachycardia or third-degree AV block. Treatment is aimed at the primary cause.

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 ...