ECG Pointers: Is it Torsade de Pointes?
- Jun 13th, 2018
- Lloyd Tannenbaum
Authors: Lloyd Tannenbaum, MD (EM Resident Physician, San Antonio, TX) and Jamie Santistevan, MD (EM Physician, Presbyterian Hospital, Albuquerque, NM) // Edited by: Manpreet Singh, MD (@MPrizzleER – Assistant Professor of Emergency Medicine / Department of Emergency Medicine – Harbor-UCLA Medical Center) and Brit Long (@long_brit – EM Attending Physician, San Antonio, TX)
Welcome to this edition of ECG Pointers, an EMDocs series designed to give you high yield tips about ECGs to keep your interpretation skills sharp. For a deeper dive on ECGs, we will include links to other great ECG FOAMed!
You are on call overnight, and the nurse tells you that your patient just had the rhythm seen on the rhythm strip provided. The patient has a history of schizophrenia and is on multiple psych medications. He’s also on CRRT (that’s continuous renal replacement therapy) since he’s had trouble controlling his potassium. What do you want to do? Do you shock him? Connect to the crash cart? Load with any medications? Panic and call cardiology? Or are you unimpressed and just want to continue sleeping?
Lead II and III are pictured here. There is sinus rhythm seen at the beginning of the rhythm strip followed by wide complex beats, not uniform in shape. Is this polymorphic ventricular tachycardia (torsade de pointes) or something else?
Let’s take a closer at the continuation of rhythm strips.
All of the black lines are obtained by measuring the R-R Interval between the sinus beats at the beginning of the strip. When the rhythm changes, there are still regular, narrow spikes seen buried within the wide-complex beats, easiest to see in lead III (marked by two red stars). Notice how the R-R interval is consistent including in in the area of suspected torsade. You should not be able to march out distinct QRS complexes in TDP.
What is torsade de pointes?
Torsade de pointes is a form of polymorphic ventricular tachycardia characterized by a gradual change in the amplitude of QRS complexes. It will appear as if there is “twisting” of the QRS complexes around the isoelectric line. Torsade is associated with a prolonged QT interval, which may be congenital or acquired (for example, due to medications, hypokalemia, or hypomagnesemia). Torsade usually terminates spontaneously but frequently recurs and may degenerate into ventricular fibrillation.
A prolonged QT interval means prolonged repolarization. This allows for “R on T phenomenon”, where a PVC or other natural beat fires during the preceding T- wave, resulting in torsade.
Here is an example:
What to do?
Runs of torsade can be shot and self limiting. It is imperative to identify the underlying cause and treat appropriately.
For an acute unstable episode, perform defibrillation. Patients also often respond to magnesium sulfate, give 2 g IV over 1 to 2 min. If a drug is the cause, it should be stopped, but until the drug is completely cleared, patients with frequent or long runs of torsade may sill require treatment to shorten the QT-interval. Because increasing the heart rate shortens the QT-interval, temporary overdrive pacing, IV isoproterenol, or both are often effective.
Long-term treatment is required for patients with a congenital long QT-interval syndrome. These patients may be candidates for implantable pacemaker or ICD. Family members should also be evaluated by ECG.
This patient was at risk for TDP due to the fact that he was taking multiple QT prolonging medications. The nurse had stated “Hey Doc, he’s in V Tach in lead II”. This should be your first clue, because you’re either in V Tach or not. Remember, when a nurse calls you with concerns about a patient, even when you don’t plan on doing anything, GO SEE THE PATIENT. He was hemodynamically stable, with no complaints. His EKG from the prior morning had a normal QT interval, which was reassuring. I felt good with my decision that this was artifact and there was nothing to do. Cardiology was consulted and agreed that the concerning tracing represented artifact.
And here’s some more ECG FOAMed:
- For more case examples of Torsade, check out Life in the Fast Lane ECG library.
- For an in depth review of polymorphic ventricular tachycardia, visit Dr. Smiths ECG blog post.
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