Difference between revisions of "QT prolongation"

(Evaluation)
(Pause Dependent (precipitated by bradycardia))
Line 95: Line 95:
 
*Unstable/sustained [[torsades]]→ [[defibrilation]] (unsynchronized)
 
*Unstable/sustained [[torsades]]→ [[defibrilation]] (unsynchronized)
 
*Stable
 
*Stable
**Treat underlying prob
+
**Treat underlying etiology
 
**Increase HR ([[isoproterenol]] or [[overdrive pacing]])
 
**Increase HR ([[isoproterenol]] or [[overdrive pacing]])
 
**[[Magnesium sulfate]] IV
 
**[[Magnesium sulfate]] IV

Revision as of 20:25, 7 March 2019

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

  • 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

  • Highly consider admission, especially for QT >500

See Also

External Links

References