Difference between revisions of "QT prolongation"

(Management)
 
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***Jarvel/Lange-Nielsen
 
***Jarvel/Lange-Nielsen
 
****(+deafness; AR)
 
****(+deafness; AR)
***Romano-Ward synd
+
***Romano-Ward syndrome
****(nl hearing; AD)
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****(normal hearing; AD)
 
***Sporadic
 
***Sporadic
 
***[[Mitral valve prolapse]]
 
***[[Mitral valve prolapse]]
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**[[Methadone]]
 
**[[Methadone]]
 
*Phosphodiesterase inhibitors
 
*Phosphodiesterase inhibitors
**[[Sildenafil]], vardenafil
+
**[[Sildenafil]], [https://nizagara-online.net/vardenafil/ Vardenafil]
 
*Skeletal muscle relaxants
 
*Skeletal muscle relaxants
 
**[[Tizanidine]]
 
**[[Tizanidine]]
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*Stable
 
*Stable
 
**Treat underlying etiology
 
**Treat underlying etiology
**Increase HR ([[isoproterenol]] or [[overdrive pacing]])
+
**Increase HR >80 ([[isoproterenol]] or [[overdrive pacing]])
 
**[[Magnesium sulfate]] IV
 
**[[Magnesium sulfate]] IV
**Consider [[amiodarone]]
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**Consider [[lidocaina, pacing]]
  
 
===Adrenergic Dependent (precipited by tachycardia)===
 
===Adrenergic Dependent (precipited by tachycardia)===
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*[[ECG (Main)]]
 
*[[ECG (Main)]]
 
*[[Torsades de Pointes]]
 
*[[Torsades de Pointes]]
 +
*[[Hypomagnesemia]]
 +
*[[Hypermagnesemia]]
  
 
==External Links==
 
==External Links==

Latest revision as of 22:18, 16 September 2021

Background

  • Prolonged ventricular repolarisation → increased risk of ventricular arrythmias
    • Males >440-450 ms
    • Females >500 ms
    • Rule of thumb: Normal QT interveal is less than half of preceding RR interval
  • QT interval is from the beginning of the Q wave to the end of the T wave
    • Rate dependent and should become proportionately shorter with increasing heart rate

Clinical Features

  • Most are asymptomatic
  • History may include:
  • Medication history may include QT prolonging medications

Differential Diagnosis

Drug List

Evaluation

Workup

  • ECG
  • CBC
  • Chem 10

Diagnosis

Acquired QT prolongation
  • ECG
    • On visual inspection, QT takes up more than half the R-R distance
    • Measure QT interval in lead II or V5-6
    • QTc = QT /√R-R

Management

Pause Dependent (precipitated by bradycardia)

Adrenergic Dependent (precipited by tachycardia)

Disposition

  • Consider admission, especially for QT >500 or if symptomatic
  • May require consultation for discontinuation of QT prolonging medications
  • Avoid prescribing medications that may contribute to prolonged QT

See Also

External Links

References