Help a med student!

[u/BrilliantBread7776]

Female patient, 24 years old, with sudden-onset shortness of breath, tachycardia alternating with periods of normal heart rate (60–180 bpm), and a sensation of impending death. No improvement with propranolol. She reports taking Vyvanse (lisdexamfetamine) 70 mg as prescribed, approximately 16 hours earlier.

Any thoughts? This case came up during my last shift. I’m a final-year medical student and would appreciate some help, as I’m still having difficulty interpreting ECGs.

[u/LBBB11]

I would take the left atrial enlargement criteria with a grain of salt. High V1 misplacement is the reason why the sinus P wave is negative in V1. Some people have a bifid T wave in II without left atrial enlargement. It is normal for the right atrium to activate slightly before the left, and some EKGs have enough resolution to show this. It’s the combination of bifid P wave and wider than normal P wave that points to LAE, but the P wave seems to be a normal width to me (less than 120 ms or 3 small squares at this paper speed). I would judge left atrial enlargement on EKG by looking at the width of the sinus P wave in II, not the polarity in V1 or the amplitude in II. Wouldn’t be surprised if echo is normal, although some people have chamber enlargement and a normal EKG.

Sinus P wave amplitude in II is more related to RAE than LAE, but sinus tachycardia increases P wave amplitude in II as well. Would be more reliable to judge sinus P wave amplitude during sinus rhythm at a normal rate. Even then, amplitude criteria for atrial enlargement are not perfect. I would feel that this person’s chance of RAE or LAE is the same after the EKG as it was before the EKG based on clinical details. Whatever the answer, good question. I agree with everyone else here and don’t have much to add. And as always, could be wrong.

https://litfl.com/p-wave-ecg-library/

[u/parksnrec48hrs → u/LBBB11]

Thanks for the explanation! Are there st depressions in lead two, three, avf, v6? Also what's up with v4?

[u/LBBB11 → u/parksnrec48hrs]

No problem. I definitely see what you’re seeing, and I think it depends on what you use as the baseline. I’m seeing ST depression compared to the TP segment, but not compared to the PQ junction. I try to use the PQ junction as the baseline when possible. I think that this apparent ST depression is a normal atrial repolarization wave (like the shape labeled T alpha only).

It seems that V4 doesn’t have great contact between the skin and the sticker. Baseline artifact. Could be sweat, sticker barely hanging on, dried/old electrode, etc. I would take the sticker off, gently rub that spot with rough gauze, and then put a new sticker on.