Atrial Rhythms

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    84 year old who experiences syncope.

    31 year old male who is asymptomatic and has a history of cardiomyopathy.

    Questions

    Question 1: Where do you see the blocked PAC? 

    Question 2: Why does the P wave not conduct?

    Key Findings

    -Sinus rhythm with blocked PAC

    Coding for Boards

    -Sinus Rhythm

    -Premature atrial complexes

    -Left atrial abnormality

    Answers

    Question 1: The PAC is difficult to see because it is imbedded in the T wave of the preceeding beat. Careful inspection of the ST segment and early portion of the T wave in the Lead II rhythm strip will reveal the PAC.

    Question 2: The PAC occurs early enough to encounter the AV node during its refractory period.