ST Segment Changes With Paced Rhythm
These recordings illustrate the effect of acute infarction on the EKG
in a patient with paced ventricular rhythm.
- In the first recording, note that the QRS has a LBBB like morphology.
- In the second tracing, note the ST elevation in leads V3 and V4 .
- In the third tracing, note that there has been a change in the "conduction"
of the paced complexes. There is now a RBBB like pattern with ST elevation
in V1 which is in the same direction as the main QRS (the R') in this case.
This is highly unusual as the ST segment vector usually is spatially opposite
to the QTS vector in the case of paced rhythm and bundle branch blocks.
Concordant directions as in this case can indicate an acute injury.
- It is unclear why the QRS morphology changed. This may represent the
effect of the MI or perhaps could represent a competing rhythm that was
fusing with the paced rhythm.
- The patient unfortunately did not survive the MI.
Dr. M. Rosengarten