A young man with back spasms

Written by Pendell MeyersFirst see this ECG without clinical context:What do you see? Do you agree with the computer ' s read of " nonspecific ST abnormality? "The ECG is diagnostic of hypokalemia. There is diffuse minimal STD, with prolonged QT interval and characteristic " up-down " T-wave morphology in the precordial leads which is being caused by U-waves. V2 has an especially pronounced U-wave, but there is also a slightly wandering baseline. This morphology is very unlikely to be due to ischemia, and to an experienced electrocardiographer is nearly pathognomonic of hypokalemia +/- other concomitant factors such as hypomagnesemia, medication-induced long QT, etc.Now here is the clinical scenario:A young male in his 20s presented with back pain which he described as " back spasms " and weakness worsening all week and which became severe yesterday after lifting some boxes. Only upon review of his chart, I became aware that he had a history of CKD and eating disorder resulting in extreme electrolyte disturbances.So I ordered this ECG:We diagnosed hypokalemia based on the ECG and history. The computer read the QT and QTc intervals as 449ms and 488ms, respectively.Do you agree?No!Here is the QT interval measured out:It is actually almost impossible to measure the QT interval because of the U-wave.So let ' s measure the QU interval.QT interval = 560 ms. Using Bazett ' s formula, with HR=71 bpm, then QTc = 609 ms. Using Fridericia ' s formula, 592 ms.We gave him magnesium 2 gm I...

Source: Dr. Smith's ECG Blog - October 17, 2018 Category: Cardiology Authors: Pendell Source Type: blogs