A 33 year-old male with PMH significant for paroxysmal A/fib, alcoholism, history of alcohol withdrawal seizures, was presented to the emergency department c/o symptoms of alcohol withdrawal: shaking, nausea, and vomiting. Patient normally consumes 12-18 drinks daily. This morning he took 1 drink to prevent withdrawal but did not feel better. Because of his profuse shaking, a girlfriend was concerned that he was having a seizure and brought him to emergency department.

ECG that was taken when the patient got to emergency department:

As you can see, the interpretation is somewhat affected by baseline shivering, which is expected in a patient who is having significant tremors. Sinus rhythm, QRS is narrow. QTc seems prolonged, and it's read as 532 ms by a computer. V3-V4 shows biphasic T-waves, which are new compared to patient's baseline ECG.

This is the patient's baseline ECG:

While in emergency department, patient had a GTC seizure, then lost pulses and went into torsades-de-pointes. Patient was defibrillated at 200J and given Mag as per ACLS protocol, went into V/fib, then defibrillated again, then back to torsades. ROSC was achieved after 5 min and defibrillation x3. Patient was intubated and put on Propofol gtt.

Labs:
WBC 3.4, Hgb 13.8, Hct 38.1, platelets 55, MCV 104
Na 138, K 3.1, Cl 96, CO2 21, glucose 132, BUN 10, creatinine 0.74
Lactate 2.9
Mag 1.1 (normal 1.7 – 2.4 mg/dL)
Phos 2.2

ECG after ROSC:

Patient was discharged home in few days neurologically intact. Patient was extensively evaluated by Cardiology service. His V/fib arrest was thought to be caused by severe electrolyte abnormalities.

Teaching points:

• The primary ECG abnormality in hypomagnesemia is prolonged QTc. When you see it on ECG, it is helpful to run through your DDx and order Mag level if appropriate.
• Do not underestimate Magnesium deficiency. When it's low enough, it actually can cause bad stuff, such as torsades-de-pointes in our case.
• ACLS protocol is written by smart people: give 2 gr of Mag IV push to torsade patients!
• When correcting Mag, do not forget to correct K, and vice versa!

Keywords: magnesium, hypomagnesemia, torsades de pointes, ventricular fibrillation, defibrillation, v/fib arrest, prolonged QT, prolonged QTc

Courtesy of Karima Sajadi, MD

The information on these pages is provided for general information only and should not be used for diagnosis or treatment, or as a substitute for consultation with a physician or health care professional. If you have specific questions or concerns about your health, you should consult your health care professional.

The images being used are for illustrative purposes only; any person depicted is a model.

 
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