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Long QT Interval

Alec M Wilhelmi, MD and Leigh A Romero, CAQSM, MD Reviewed 06/2021
 


BASICS

DESCRIPTION

  • QT interval: the interval from the beginning of the QRS complex to the end of the T wave on the surface electrocardiogram (ECG). This represents the period from the onset of ventricu...

DIAGNOSIS

HISTORY

  • Incidental finding on ECG in asymptomatic patients

  • Evaluate for syncope, presyncopal episodes, palpitations, and associated precipitating events (emotional triggers, swimming, diving).

  • ...

TREATMENT

GENERAL MEASURES

  • Treat VT, TdP, and VF emergently per ACLS guidelines.

  • Withdraw offending agents and correct electrolytes (2)[C].

  • Treat underlying disorder in the setting of gastrointestinal i...

ONGOING CARE

FOLLOW-UP RECOMMENDATIONS

Patient Monitoring

  • On routine visits, ask about syncope, presyncope, and palpitations in those who have QTc prolongation.

  • Consider ECG and/or outpatient cardiac rhy...

REFERENCES

1
Kramer  DB, Zimetbaum  PJ. Long-QT syndrome. Cardiol Rev.  2011; 19(5): 217– 225.
2
Kallergis  EM, Goudis  CA, Simantirakis  EN, et al. M...

SEE ALSO

Algorithms: Cardiac Arrhythmias; Torsade de Pointes (TdP): Variant Form of Polymorphic Ventricular Tachycardia (VT) 

CODES

ICD10

I45.81 Long QT syndrome 

SNOMED

  • 9651007 Long QT syndrome (disorder)

  • 442946007 Aquired long QT syndrome

  • 442917000 Congenital long QT syndrome

CLINICAL PEARLS

  • Evaluate for acquired causes before making a diagnosis of hereditary LQTS.

  • For accurate diagnosis, calculate QTc manually.

  • Magnesium sulfate is the treatment of choice during ACLS for Td...

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