What is First Degree AV Block
It is the prolongation of PR >0.22 sec. Every atrial depolarisation is followed by conduction to
the ventricles, but with delay.
Causes of First Degree AV Block
• Normally found in athletes (due to increased vagal tone).
• Drugs (digitalis toxicity).
• Acute myocardial infarction (common in inferior MI).
• Acute rheumatic carditis.
• In elderly (atherosclerosis).
• PR interval—prolonged >0.22 second (normal 0.12–0.20 second).
Treatment of First Degree AV Block
No specific treatment is required.