Sunday, May 27, 2018

Weakness, head trauma, and an abnormal ECG

Written by Pendell Meyers, with edits by Steve Smith

A man in his 50s with history of CAD s/p CABG, CHF, and COPD presented after several falls attributed to acute generalized weakness.  Several had reportedly resulted in head trauma.  There was a normal neurologic exam.

Here is his ECG:

What do you think?

Sinus rhythm at around 60 bpm. There is STD with "down-up" T-waves in V2-V6, or more accurately T-wave inversion followed by large U-waves. The morphology is classic for hypokalemia. The computerized QT interval and QTc were 676ms and 663ms, which is really a measure of the Q-U interval instead of the QT interval. In other words, when the QT interval looks impossibly long, then you should check to see if what you thought was a T-wave is really a U-wave.

This ECG is not consistent with posterior ischemia given the overall morphology and U-waves, however you should remember to include posterior ischemia in your differential of STD that is maximal in V3-V4. More importantly, the patient has generalized weakness and no chest pain, SOB, or clear anginal equivalent.

Intracranial hemorrhage and/or Takotsubo ("stress") cardiomyopathy may present with STD and prolonged QT interval, but this is very different because of the U-waves.

We just presented an abstract discussing our ECG findings in hundreds of ICH cases (traumatic and non traumatic), and prolonged QTc and STD were the findings with the highest correlation to low GCS on arrival and death in this setting. I will be discussing these results in a separate post later.

The potassium returned at 2.6 mEq/L. Magnesium was 1.6 mEq/L. Head CT was negative. Two serial troponins were undetectable. Potassium and magnesium were supplemented, and his dose of diuretic was decreased. He did well.

Here is the patient's post-treatment ECG, with potassium = 3.8 mEq/L several hours prior to the ECG:

Computerized QT and QTc = 464 and 474 ms. There is still a tiny bit of dowsloping STD in V5-V6 with flat/inverted T-wave. This could be baseline, but it would not be possible to tell without a baseline ECG.

Here is the patients prior baseline ECG, two months prior to the presentation ECG:
Almost identical to the post-treatment ECG above.

See more examples to lock in the pattern recognition:

A woman in her 20s with syncope

Are These Wellens' Waves??

Look at These "T"-Waves

Why is this patient weak?

Diabetic Ketoacidosis: is there hypokalemia?

Recommended Resources