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Calculator: QT interval correction (ECG) in adults and children


Calculator: QT interval correction (ECG) in adults and children

 
Input
 
QT Interval   millisec
ECG heart rate measure  

 
Results
 
Important: Inputs must be complete to perform calculation.

 
 
Heart rate   BPM
RR interval   millisec
QT Interval corrected Bazett   millisec
QT Interval corrected Fridericia   millisec
QT Interval corrected Framingham   millisec
QT Interval corrected Hodges   millisec
 
Decimal precision  

 
 

 

 
Notes
  • The input “ECG heart rate measure” is either the RR interval in milliseconds of the beat prior to the QT interval, or the heart rate in beats per minute.
  • For more information on the clinical usefulness of the corrected QT interval calculations, please see UpToDate topics on basic electrocardiogram interpretation and both acquired and congenital long QT syndrome.
  • ECG: electrocardiogram; BPM: beats per minute.

 
Equations used
 
QT_Interval_corrected_Bazett = QT_Interval / sqr(RR_interval/1000)
QT_Interval_corrected_Fridericia = QT_Interval / (RR_interval/1000)1/3
QT_Interval_corrected_Framingham = QT_Interval + (0.154 * (1000 - RR_interval))
QT_Interval_corrected_Hodges = QT_Interval + (1.75 * (Heart_rate - 60))

 

 
Reference QT intervals for females
 
Bazett~355~482
FormulaLower limit of normal (millisec)Upper limit of normal (millisec)
Fridericia
348
468
Framingham
351
467
Hodges
348
465

 
Reference QT intervals for males
 
Bazett~346~472
FormulaLower limit of normal (millisec)Upper limit of normal (millisec)
Fridericia
349
448
Framingham
350
449
Hodges
351
446

 
References
  1. Bazett HC. An analysis of the time relationships of electrocardiograms. Heart 1920; 7:355.
  2. Fridericia L. Die systolendauer im Elektrokardiogramm bei normalen menschen und bei herzkranken. Acta Med Scand 1920; 53:469.
  3. Sagie A, Larson MG, Goldberg RJ, et al. An improved method for adjusting the QT interval for heart rate (the Framingham Heart Study). Am J Cardiol 1992; 70:797.
  4. Hodges MS, Salerno D, Erlinen D. Bazett's QT correction reviewed: evidence that a linear QT correction for heart rate is better. J Am Coll Cardiol 1983; 1:694.
  5. Vandenberk B, Vandael E, Robyns T, et al. Which QT Correction Formulae to Use for QT Monitoring? J Am Heart Assoc 2016; 5:e003264.
Only digits 0 to 9 and a single decimal point (".") are acceptable as numeric inputs. Attempted input of other characters into a numeric field may lead to an incorrect result.

Information on this page may not appear correctly if printed.

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