Hypokalæmia - Giant U Waves

Report:

Sinus rhythm 52/min

Borderline right axis deviation +91o

Right atrial abnormality

Late transition

Prolonged QT (QU) interval 0.72”

Comment:

It would not be possible to tell whether the apparent QT prolongation is due to a large U wave that had merged with the T wave. Knowing the patient’s potassium to be 2.3 mEq/L makes the presence of a large U wave virtually certain.

The ECG looked unchanged when the patient returned to Casualty three weeks later, with potassium 2.1 mEq/L (Fig 71a below). There were no arrhythmias, ever. Some patients with profound weakness from hypokalæmia appear, for reasons unknown (to me, at least) immune to its proarrhythmic propensities.

Normalised ECGs were not available, perhaps because the patient would leave the hospital as soon as his strength returned, further to cleanse his crypts of Lieberkühn!

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