Question of the Week: November 5, 1999

Identify the following ECG rhythm.


Sinus rhythm with blocked PAC's (in a trigeminal pattern).

Note the long pause identified by the blue horizontal line.  Look at the T wave on the beat prior to each pause...the T wave has a notch or buried P wave (identified by red arrow).   The P wave of this premature atrial contraction has come too early in the cycle to be conducted, resulting in a blocked QRS or non-conducted PAC.

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Last Updated March 24, 2009 | © 2007, LHSC, London Ontario Canada