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📈 QTc Calculator (Bazett & Fridericia)

UseScreen for QT prolongation and torsades risk before or during QT-prolonging therapy.

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SourceAHA/ACCF/HRS scientific statement on QT. Circulation 2009

Runs locally in your browser (no PHI uploaded). For licensed clinicians — not a substitute for clinical judgement.
Stored on this device for revisit reminders

This-shift next steps

After scoring: open the scene pack, peer scores, and the matching pathway. Local reference — no HIS write.

Scene next step
📋circ hemoOpen scene pack →
Related scores
Score + version; reference only — not a substitute for care · no HIS write

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Methodology · worked example, guidelines & full notes
Clinical takeaway

Bazett over-corrects at fast and under-corrects at slow heart rates.

When to use

Screen for QT prolongation and torsades risk before or during QT-prolonging therapy.

How it works

Bazett QTc = QT/√RR; Fridericia QTc = QT/∛RR (RR in seconds = 60/HR). Prolonged: > 450 ms (men) / > 470 ms (women); > 500 ms high risk.

Key points

  • Bazett over-corrects at fast and under-corrects at slow heart rates.
  • Fridericia is preferred outside 60–100 bpm.
  • Wide QRS inflates QT — interpret with care.

References

Worked calculation

The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.

QT interval400 ms
Heart rate75 bpm
SexMale

→QTc (Bazett)447ms

  • QTc (Fridericia)：431 ms
  • Prolonged if：> 450 ms (male); > 500 ms = high torsades risk
Verification & sources · governance
FAQ

Frequently asked questions

What are the limits and cautions when using QTc Calculator (Bazett & Fridericia)?
For licensed clinicians and clinical researchers. Interpret results with history, investigations and local protocols; not a diagnosis or prescription, and not a substitute for multidisciplinary decision-making or local guidelines.
Does QTc Calculator (Bazett & Fridericia) upload patient data? Where is it calculated?
Calculation runs locally in the browser; inputs and results are not uploaded. For licensed clinicians only; interpret with history, investigations and local protocols — not a diagnosis or prescription.
How is QTc Calculator (Bazett & Fridericia) calculated in practice? Can you show a worked example?
Inputs: QT interval 400 ms, Heart rate 75 bpm, Sex Male → Result: QTc (Bazett) 447 ms（QTc (Fridericia): 431 ms, Prolonged if: > 450 ms (male); > 500 ms = high torsades risk）
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