SVT with ectopy
First Glance:
From across the room it looks like a narrow complex tachycardia.
Discussion:
It was cut off in the scan, but the upper trace is MCL and the lower trace is from a swan, marked as the PA pressure.
Looking at MCL, we see a rapid rhythm- rate a little under 150. There are regular QRS complexes that don’t appear to hit 120 ms. The T waves appear inverted, and I can’t really tell if there are P’s or not. Most likely there are negative P’s with a normal PR interval, but I just can’t be sure from this trace.
MCL’s negative electrode is LA and positive is placed wherever. Usually in the septal position to give a V1/V2ish lead. If that is the case here then the predominantly positive complexes seen here would be concerning for RVH, right heart strain, or posterior infarct. All speculation, though. We would need to check where this MCL lead is placed on the patient, as like the standard precordial ‘V’ leads its normal morphology is completely dependent on the position.
You can pick out two PVCs (of markedly different morphology) a little ways past half, and one more PVC near the end of the strip.
The PA cath shows a regular but wildly excursive trace between 42 and 66- high, with swings that are possibly from a position in a turbulent portion of the PA.
Final Impression?
Supraventricular rhythm @ ~130 bpm with polymorphic PVCs.
Management implications:
Check where MCL is placed. 12L for evaluation of rhythm +/- ischemia. ?Reposition PA cath.
The Take-home Point:
You can not interpret morphology unless you know what leads you are looking at. “MCL” could be placed anywhere, and it’s interpretation is fairly useless without knowing where on the chest it is. The same goes for the ubiquitous tele monitor ‘V’ lead, which could be placed wherever the RN likes. Even a labeled lead (“V3” etc) might not be in the right place.
I have seen plenty of 12L with obviously labeled specific leads which looked like regional abnormalities but were just lead misplacement from a haphazard provider or inability to place a lead correctly due to wounds, drains, etc.
One star strip. Students should identify the rhythm correctly.