QT dispersion in sinus beats and ventricular extrasystoles in normal hearts.

C P Day, J M McComb, R W Campbell

Department of Academic Cardiology, Freeman Hospital, Newcastle upon Tyne.

OBJECTIVE--Recent studies have suggested that QT interlead variability (dispersion) on the surface electrocardiogram may have potential as a measure of recovery time dispersion. To test this hypothesis further QT dispersion occurring in sinus beats was compared with that in ventricular extrasystoles. DESIGN--Simultaneous electrocardiograms were recorded at 50 mm/s during sinus rhythm in a drug free state while ventricular extrastimuli were introduced by programmed right ventricular stimulation at different coupling intervals. QT dispersion, defined as the difference between the maximum and minimum QT, was calculated separately for the extrasystoles and preceding and following sinus complexes. To correct for the influence of the number of measurable leads on QT dispersion, an "adjusted" QT dispersion calculated as QT dispersion/square root of the number of measurable leads, was used to compare sinus complexes and extrasystoles. PATIENTS--Nine patients were studied who were undergoing electrophysiological study for investigation of palpitation and were found to have electrically normal ventricles. RESULTS--At all coupling intervals tested "adjusted" QT dispersion was significantly greater in the ventricular extrasystoles than in either the preceding or following sinus complexes. For the coupling interval 350 ms, the 95% confidence intervals for the difference between means was 52 to 78 ms (preceding sinus complex) and 56 to 82 ms (following sinus complex) (p less than 0.00001). There was no correlation between the coupling interval and the magnitude of the "adjusted" QT dispersion. CONCLUSION--These results accord fully with expected differences in ventricular recovery time dispersion and offer further support for the hypothesis that QT dispersion reflects regional variation in ventricular recovery. If substantiated by invasive studies, these findings have wide implications for both the usefulness and the method of QT measurement.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

• Osadchii, O. E., Bentzen, B. H., Olesen, S. P. (2009). Chamber-specific effects of hypokalaemia on ventricular arrhythmogenicity in isolated, perfused guinea-pig heart. Exp Physiol 94: 434-446 [Abstract] [Full Text]  
• Okmen, E., Sanli, A., Uyarel, H., Dayi, S., Tartan, Z., Cam, N. (2006). Impacts of Glycoprotein IIb/IIIa Inhibition on QT Dispersion After Successful Percutaneous Coronary Intervention. ANGIOLOGY 57: 273-281 [Abstract]  
• Dursunoglu, D., Dursunoglu, N., Evrengul, H., Ozkurt, S., Kilic, M., Fisekci, F., Kuru, O., Delen, O. (2005). QT interval dispersion in obstructive sleep apnoea syndrome patients without hypertension. Eur Respir J 25: 677-681 [Abstract] [Full Text]  
• Sakata, K, Shimizu, M, Ino, H, Yamaguchi, M, Terai, H, Hayashi, K, Kiyama, M, Hayashi, T, Inoue, M, Mabuchi, H (2003). QT dispersion and left ventricular morphology in patients with hypertrophic cardiomyopathy. Heart 89: 882-886 [Abstract] [Full Text]  
• Dabrowski, A., Kramarz, E., Piotrowicz, R., Kubik, L. (2000). Predictive Power of Increased QT Dispersion in Ventricular Extrasystoles and in Sinus Beats for Risk Stratification After Myocardial Infarction. Circulation 101: 1693-1697 [Abstract] [Full Text]  
• De Sutter, J, Tavernier, R, Van de Wiele, C, De Backer, J, Kazmierczak, J, De Backer, G, Dierckx, R, Jordaens, L (1999). QT dispersion is not related to infarct size or inducibility in patients with coronary artery disease and life threatening ventricular arrhythmias. Heart 81: 533-538 [Abstract] [Full Text]  
• Jordaens, L. J. L. M. (1999). The clinical value of QTdispersion: new perspectives on the assessment of cardiac repolarization more than 75 years after Bazett's formula. Europace 1: 73-76  
• Yetman, A. T., Hamilton, R. M., Benson, L. N., McCrindle, B. W. (1998). Long-term outcome and prognostic determinants in children with hypertrophic cardiomyopathy. J Am Coll Cardiol 32: 1943-1950 [Abstract] [Full Text]  
• Yetman, A. T., McCrindle, B. W., MacDonald, C., Freedom, R. M., Gow, R. (1998). Myocardial Bridging in Children with Hypertrophic Cardiomyopathy -- A Risk Factor for Sudden Death. NEJM 339: 1201-1209 [Abstract] [Full Text]  
• Tutar, H E., Öcal, B, Imamoglu, A, Atalay, S (1998). Dispersion of QT and QTc interval in healthy children, and effects of sinus arrhythmia on QT dispersion. Heart 80: 77-79 [Abstract] [Full Text]  
• Zabel, M., Klingenheben, T., Franz, M. R., Hohnloser, S. H. (1998). Assessment of QT Dispersion for Prediction of Mortality or Arrhythmic Events After Myocardial Infarction : Results of a Prospective, Long-term Follow-up Study. Circulation 97: 2543-2550 [Abstract] [Full Text]  
• Zaidi, M, Robert, A, Fesler, R, Derwael, C, Brohet, C (1997). Dispersion of ventricular repolarisation: a marker of ventricular arrhythmias in patients with previous myocardial infarction. Heart 78: 371-375 [Abstract] [Full Text]  
• Perkiomaki, J. S., Ikaheimo, M. J., Pikkujamsa, S. M., Rantala, A., Lilja, M., Kesaniemi, Y. A., Huikuri, H. V. (1996). Dispersion of the QT Interval and Autonomic Modulation of Heart Rate in Hypertensive Men With and Without Left Ventricular Hypertrophy. Hypertension 28: 16-21 [Abstract] [Full Text]  
• van de Loo, A., Klingenheben, T., Hohnloser, S. H. (1996). Amiodarone Therapy After Previous Sotalol-induced Torsade de Pointes: Analysis of QT Dispersion to Predict Proarrhythmia. J CARDIOVASC PHARMACOL THER 1: 75-78 [Abstract]