Which of the following is a feature of first degree AV block?: (A) PR interval > 200 ms, (B) Inversion of T wave, (C) Progressive shoenting of PR interval, (D) Presence of U wave
Answer is A. Answer- A. PR interval > 200 msFirst-degree AV block (PR interval >200 ms) is a slowing of conduction through the AV junction.The site of delay is typically in the AV node but maybe in the atria, bundle of His, or His-Purkinje system.In second degree AV block there is an intermittent failure of electrical impulse conduction from atrium to ventricle.Second-degree AV block is subclassified as Mobitz type I (Wenckebach) or Mobitz type II.