QTC

QTC may refer to:

  • Quantum Tunneling Composite
  • QTc, a time measurement of a portion of a heartbeat
  • Queensland Theological College
  • Queensland Turf Club
  • Quinnipiac tribal council
  • The radio Q code for a pending message count
  • QT interval

    In cardiology, the QT interval is a measure of the time between the start of the Q wave and the end of the T wave in the heart's electrical cycle. The QT interval represents electrical depolarization and repolarization of the ventricles. A lengthened QT interval is a marker for the potential of ventricular tachyarrhythmias like torsades de pointes and a risk factor for sudden death.

    Correction for heart rate

    Like the R-R interval, the QT interval is dependent on the heart rate in an obvious way (the faster the heart rate the shorter the R-R Interval and QT interval) and may be adjusted to improve the detection of patients at increased risk of ventricular arrhythmia. Modern computer-based ECG machines can easily calculate a corrected QT (QTc), but this correction may not aid in the detection of patients at increased risk of arrhythmia. There are a number of different correction formulas.

    The standard clinical correction is to use Bazett's formula, named after physiologist Bazett, calculating the heart rate-corrected QT interval (QTcB). Please be aware that Bazett's formula is based on observations of only 12 patients in 1920 and does not meet current scientific quality standards. A more robust method is the Framingham correction based on the Framingham Heart study, recent longterm cohort data of over 5000 subjects.

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