Corrected QT Interval
QT interval corrected for heart rate, by both Bazett and Fridericia.
When to use it. Assessing QT prolongation before or during a QT-prolonging drug, or in suspected channelopathy.
تُعرض معلومات السلامة الطبية في هذه الصفحة بالإنجليزية. لم يراجعها بعد طبيب يقرأ العربية، والاعتماد على ترجمة لم يتحقق منها أحد ليس آمنًا.
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Limits of this score. Bazett over-corrects at fast rates and under-corrects at slow ones — a tachycardic patient can look falsely prolonged. Fridericia is more stable and is what regulators use. Neither correction is valid in atrial fibrillation or with a wide QRS; measure in lead II or V5, and never from an automated read alone.
Sources
- Bazett HC. An analysis of the time-relations of electrocardiograms. Heart 1920;7:353–70.
- Fridericia LS. Die Systolendauer im Elektrokardiogramm bei normalen Menschen. Acta Med Scand 1920;53:469–86.
- Rautaharju PM, et al. AHA/ACCF/HRS recommendations for the standardization of the ECG, part IV. Circulation 2009;119:e241–50.
Where this is written from. This site is written from Indian clinical practice. Drug availability and brand names, vaccination schedules, national health programmes and some reference cut-offs differ between countries — a schedule or a threshold that is standard here may not be standard where you are. If you are reading outside India, check anything on this page against your own country’s guidance before you act on it.
Educational use only — not medical advice. Never a substitute for clinical judgement.