Atrioventricular Blocks

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    68 year old male with syncope.

    68 year old male with syncope.

    Questions

    Question 1: Why do some of the T waves look different than others?

    Question 2: Where in the conduction system does the second PAC fail to conduct?

    Question 3: Why does one of the PACs conduct while the other PACs do not?

    Key Findings

    -Sinus Rhythm

    -Premature atrial contractions (intermittently blocked)

    Coding for Boards

    -Sinus Rhythm

    -Atrial premature complexes

    -Low voltage, limb leads

    Answers

    Question 1: The PACs occur during the T wave and distort the normal appearance of the T waves.

    Question 2: AV node.

    Question 3: The conducted PAC falls outside of the refractory period of the AV node. The blocked PACs fall within the refractory period of the AV node.