Please confirm topic selection

Are you sure you want to trigger topic in your Anconeus AI algorithm?

Please confirm action

You are done for today with this topic.

Would you like to start learning session with this topic items scheduled for future?

Updated: Dec 7 2021

Torsades de Pointes

Images
https://upload.medbullets.com/topic/121715/images/torsades_de_pointes_tdp.jpg
  • Snapshot
    • A 45-year-old woman presents to the emergency room for a syncopal episode. She currently experiences lightheadedness and palpitations. Her medications include ondansetron and oral contraceptives. An electrocardiogram reveals torsades de pointes. She is given magnesium sulfate.
  • Introduction
    • Clinical definition
      • a polymorphic ventricular tachycardia characterized by sinusoidal and cyclic alterations on electrocardiogram (ECG)
    • Associated conditions
      • congenital long QT syndrome
        • Jervell and Lange-Nielsen syndrome
          • autosomal recessive
          • associated with congenital sensorineural deafness
        • Romano-Ward syndrome
          • autosomal dominant
          • no sensorineural deafness
  • Epidemiology
    • Demographics
      • female > male
        • women have longer QT intervals
    • Risk factors
      • ↓ magnesium
      • ↓ potassium
  • Etiology
    • Familial
    • Drugs (ABCDE)
      • class IA Antiarrhythmics (quinidine, procainamide, and disopyramide) due to ↑ QT interval
      • class III Antiarrhythmics (sotalol and ibutilide)
      • antiBiotics
      • antipsyChotics
      • antiDepressants
      • antiEmetics
      • diuertics (e.g., furosemide)
    • Pathogenesis
      • torsades de pointes is thought to result from prolonged repolarization and early afterdepolarizations
        • when early afterdepolarizations reach the threshold potential and depolarize the cell membrane, triggered activity occurs, resulting in additional action potentials
          • the triggered activity can produce torsades de pointes in susceptible patients
  • Presentation
    • Symptoms
      • palpitations
      • dizziness
      • syncope
      • symptoms may be triggered by stress
      • sudden cardiac death
    • Physical exam
      • tachycardia
      • pallor
  • Studies
    • Labs
      • serum electrolytes (↓ magnesium and potassium)
    • Electrocardiogram (ECG)
      • if in sinus rhythm
        • prolonged QT interval
        • pathological U waves
      • if in an episode
        • change in polarity of QRS around the isoelectric line
        • sinusoidal waveform
  • Differential
    • Supraventricular tachycardia
      • distinguishing factor
        • non-sinusoidal waveforms on electrocardiogram
  • Diagnosis
    • Making the diagnosis
      • based on clinical presentation and electrocardiogram
  • Treatment
    • Conservative
      • discontinue all QT prolonging drugs
        • indication
          • for all patients
        • outcomes
          • torsades de pointes due to drugs typically do not recur after withdrawal of the drug
    • Medical
      • magnesium sulfate
        • indications
          • for all patients
        • mechanism of action
          • suppresses early afterdepolarizations to terminate the arrhythmia
          • Mg2+ decreases the influx of calcium and lowers the amplitude of the early afterdepolarizations
      • β-antagonists
        • indications
          • long-term therapy for patients with congenital long QT syndrome
          • only for those without bradycardia
        • drugs
          • propranolol
          • esmolol
    • Operative
      • pacing
        • indication
          • long-term therapy for patients who are symptomatic despite pharmacologic treatment
          • typically for patients with congenital long QT syndrome
  • Complications
    • Ventricular fibrillation
  • Prognosis
    • Usually preceded by a period of long QT intervals
    • Typically resolves spontaneously but may degenerate into ventricular fibrillation and death
Card
1 of 0
Question
1 of 7
Private Note