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Letters to the Editor: Letters & Announcements

Why Bazett’s Formula?

Hegarty, Dominic, BSc, BMedSc, FRCA, RSCI

Section Editor(s): Saidman, Lawrence

Author Information
doi: 10.1213/01.ane.0000265664.14194.21
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To the Editor:

Much variability in the QT interval in health and disease is accounted for by differences in heart rate, leading to difficulties when determining the effect of disease and drugs on the QT interval. Historically, Bazett’s formula (1) has been used most often because of its simplicity to estimate the QT interval; however, it has been criticized for its inaccuracy at both higher and lower heart rates (2,3). Evaluation of the QT interval without a correction formula is now possible with the use of nomogram of normal QT interval at various heart rates and this has been used successfully in some pathological conditions to date (4). Perhaps Sen et al. (5) should apply this nomogram to their data and in this way strengthen the fundamental outcome measurement (i.e., QT interval) to help support their hypothesis.

Dominic Hegarty, BSc, BMedSc, FRCA, RSCI

Department of Anaesthesia and Intensive Care medicine

Cork University Hospital

Cork, Ireland

dominichegarty@hotmail.com

REFERENCES

1. Bazett HC. An analysis of time relations of the electrocardiograms. Heart 1920;7: 353–70
2. Funck-Brentano C, Jaillion R. Rate-corrected QT interval: techniques and limitations. Am J Cardiol 1993;72:17B–22B
3. Emori T, Ohe T, Aihara N, Kurita T, Shimizu W, Kamakura S, Shimomura K. Dynamic relationship between the QaT interval and heart rate in patients with long QT syndrome during 24-hour Holter ECG monitoring. Pacing Clin Electrophysiol 1995;18:1909–18
4. Sugao M, Fujiki A, Sakabe M, Nishida K, Tsuneda T, Iwamoto J, Mizumaki K, Inoue H. New quantitative methods for the evaluation of dynamic changes in QT interval on 24 hour Holter ECG recordings: QT interval in idiopathic ventricular fibrillation and long QT syndrome. Heart 2006;92:201–7
5. Sen S, Ozmert G, Turan H, Caliskan E, Onbasili A, Kaya D. The effects of spinal anesthesia on QT interval in preeclamptic patients. Anesth Analg 2006;103:1250–5
© 2007 International Anesthesia Research Society