Rhythm of the Month December 2010
| 
| 
DISCUSSION
When teaching this rhythm, I share a saying I learned many years
ago… “Same, same, same….”. Before I finish the saying, let’s talk
about the rhythm first. At first glance you can see there is
something wrong. Looking at the atrial rhythm first, i.e. the P waves,
you will find a regular rhythm with a rate of 60 bpm. Next, look at the
ventricular rhythm. The rhythm is irregular, and the rate varies from
60 bpm to <20 bpm. Asking the question, is each P wave followed by
a QRS?; the answer is no. It then begs the question, the cause of the
pause is?; or why are two QRSs missing following these two P waves?
Those two P waves did not conduct to the ventricles, thus no QRS.
Remembering the QRS gives us our pulse, suddenly dropping them can
be very dangerous. Be sure to call the doctor right away when you see
this rhythm. To continue gathering the rhythms’ information, you will
find the PR intervals, that are measurable, are all the same, 0.18 seconds,
within normal parameters. The QRS complex is 0.16 seconds, wider than
normal parameters. Remember; do not call the wide QRS a bundle branch
block. You need a 12 Lead EKG to determine why the QRS is wide.
This rhythm is an example of one of two Second Degree Heart Blocks.
The key, when not sure if it is Mobitz I or Mobitz II, is the PR intervals.
Each one has its own saying to help differentiate the two.
Mobitz I: “Longer, longer, dropped, that is Wenckebach.”
Mobitz II: “Same, same, same, Mobitz II is to blame.”
INTERPRETATION
Second Degree Heart Block – Mobitz II with wide QRS