A young woman, who had been binge drinking, admitted with severe agitation and hallucinations......
Initial Mg 1.3, K=2.8 , iCa++ low normal
2gm MgSO4 was given and potassium IV. Mg level 3.2, one hour after the magnesium infusion .Telemetry showed the following (pic/video)
......and < 24 hours after treatment still with QTc prolongation.
What's the primary abnormality, besides QTc prolongation ?
How much Magnesium was given in less then 24 h with a Mg level of 3.2. Any ?
FDA Updating Azithromycin Labels To Reflect Evidence The Medication Can Contribute To Torsades De Pointes
According to Cardiovascular Business (5/15, Schlachta), the Food and Drug Administration (FDA) “is updating azithromycin drug labels to reflect evidence that the medication can contribute to a rare heart rhythm abnormality known as torsades de pointes.” In a statement, the FDA said, “Healthcare professionals should consider the risk of fatal heart rhythms with azithromycin when considering treatment options for patients who are already at risk for cardiovascular events.” The statement added, the “FDA notes that the potential risk of QT prolongation with azithromycin should be placed in appropriate context when choosing an antibacterial drug.”
I would want to ask the following questions:
ReplyDelete- Does she have baseline QTc prolongation on an ECG prior the the electrolyte abnormalities
- Is she a heavy drinker and also folate deficient?
- Does she have periods of transient paralysis as part of her presentation?
- Is her QTc prolongation symptomatic?
I would include Familial Periodic Paralysis in the differential diagnosis given the constellation of findings you present here. An excellent case that I look forward to the discussion on.
Ram
No baseline QTc prolongation. Not sure about folate, but she is a very heavy binge drinker. No known of FPP or hypoPP. No TdP occurred with these findings. Great questions. Have only seen one case of hypoPP in my career.
ReplyDeleteDo you think she has a very prominent T wave on the first tracing, or is there something else going on with that T wave ?
The patient has a "prominent U wave" on the initial tracing. However given the degree of hypokalemia it would be unlikely that her QTC is this prolonged without other abnormalities. She had severe hypomagnesemia and required 10 gm MgSO4 over 12 hours. The elevated Mg level is meaningless in this situation . Serum Magnesium only represents 1% of total body Magnesium.Even after the Magnesium infusions she still needed more K+ and even in the second tracing there is still QTc prolongation, but the U wave is gone consistent with improvements in her K+, total body Mg2+ levels.
ReplyDeleteProminent U waves
U waves are described as prominent if they are:
>1-2mm or 25% of the height of the T wave.
Causes of prominent U waves
Prominent U waves most commonly found with:
Bradycardia
Severe hypokalaemia.
Prominent U waves may be present with:
Hypocalcaemia
Hypomagnesaemia
Hypothermia
Raised intracranial pressure
Left ventricular hypertrophy
Hypertrophic cardiomyopathy
Drugs associated with prominent U waves:
Digoxin
Phenothiazines (thioridazine)
Class Ia antiarrhythmics (quinidine, procainamide)
Class III antiarrhythmics (sotalol, amiodarone)
If somebody sees an example of inverted T waves , please give me a copy....the DDx is completely different
ReplyDelete