Atrioventricular Blocks

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    79 year old male with syncope.

    79 year old male with syncope.

    Questions

    Question 1: How can this potentially be Mobitz I or Morbitz II?

    Key Findings

    -Sinus rhythm

    -2nd degree AV block type I (Mobitz I) vs. type II (Mobitz II)

    Coding for Boards

    -Sinus rhythm

    -AV block, second degree-Mobitz type II (Wenckebach) or AV block, second degree-Mobitz type I

    -Left atrial abnormality/Enlargement

    Answers

    Question 1: There is not a noticeable change in the PR interval for most of the beats. However, the first conducted PR after the pause is slightly shorter than the rest. This suggests Mobitz I as the mechanism. Another possibility however, is that the QRS associated with the P wave just after the pause is a junctional escape beat. This artifically shortens the PR interval for that beat. This would imply that the P wave is not conducted, and that the pattern is Mobitz II.