VZL 2004, 73(5):161-165

The Mode of QT Interval Expression Changes Statistical Significance of Differences

Štefan Kujaník, Miroslav Mikulecký, Amália Valachová
Ústav fyziológie Lekárskej fakulty UPJŠ Košice, Slovenská republika
I. interná klinika Lekárskej fakulty UK a Fakultnej nemocnice Bratislava, Slovenská republika

Interval QT elektrokardiogramu (elektrická systola) je prejavom heterogenity repolarizácie a jedným z ukazovateľov elektrickej stability srdca. Jeho predĺženie (QTc > 440 ms) pôsobí proarytmicky.

Cieľ práce: U mladých zdravých ľudí sledovať štatistickú významnosť rozdielov intervalu QT pri zmenách pľúcnej ventilácie podľa spôsobu vyjadrenia intervalu QT.

Výsledky: Najmenšia štatistická významnosť rozdielov je vtedy, keď je QT vyjadrený v nekorigovanej (nameranej) forme, vyššia je vtedy, keď je vo forme QTc a najvyššia pri použití nekorigovaného QT spolu s jeho pulzovou frekvenciou testované Hotellingovou štatistikou.

Závery: Spôsob vyjadrenia intervalu QT môže podstatne ovplyvniť štatistickú významnosť rozdielov QT za rôznych podmienok. Ako najvhodnejší spôsob vyjadrovania QT odporúčame vyjadrenie pomocou nekorigovaného (nameraného) QT a jeho príslušnej pulzovej frekvencie.

Keywords: Elektrokardiografia; Interval QT; Pľúcna ventilácia; Valsalvov pokus; Regresia

The electrocardiographic QT interval (electric systole) is a demonstration of heterogeneity of ventricular repolarization and one of the indicators of cardiac electrical stability. Its prolongation (QTc > 440 ms) acts proarrhythmically.

Aim: to investigate the statistical significance of QT differences according to the mode of QT expression in young healthy persons.

Results: The smallest statistical significance of differences was at QT in uncorrected (measured) form, higher at corrected QTc form, the highest at uncorrected QT together with its heart rate processed by Hotelling statistics.

Conclusion: The mode of QT expression can substantially influence the statistical significance of QT differences under various conditions. The most suitable mode of QT expressing is by our opinion the uncorrected (measured) QT interval together with its heart rate.

Keywords: Electrocardiography; QT interval; Pulmonary ventilation; Valsalva manoeuvre; Regression

Received: May 2, 2003; Published: December 1, 2004  Show citation

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Kujaník, Š., Mikulecký, M., & Valachová, A. (2004). The Mode of QT Interval Expression Changes Statistical Significance of Differences. Vojenské Zdravotnické Listy, 73(5-6), 161-165
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    References

    1. ADAMS, W. The normal duration of the electrocardio-graphic ventricular complex. J. Clin. Invest., 1936, vol. 15, p. 330-335. Go to original source... Go to PubMed...
    2. AHNVE, S. - VALLIN, H. Influence of heart rate and in-hibition of autonomic tone on the QT interval. Circulation, 1982, vol. 65, no. 3, p. 435-439. Go to original source... Go to PubMed...
    3. ASHMAN, R. The normal duration of the Q-T interval. Am. Heart J., 1942, vol. 28, p. 522-534. Go to original source...
    4. BATCHVAROV, V. - MALIK, M. Individual patterns of QT/RR relationship. Card. Electrophysiol. Rev., 2002, vol. 6, no. 3, p. 282-288. Go to original source... Go to PubMed...
    5. BATCHVAROV, VN. - SMETANA, P. - HNATKOVA, K., et al. QT-RR relationship in healthy subjects exhibits substantial intersubject variability and high intrasubject sta-bility. Am. J. Physiol. - Heart Circ. Physiol., 2002, vol. 282, no. 6, p. H2356-H2363. Go to original source... Go to PubMed...
    6. BAZETT, HC. An analysis of the time relations of electrocardiograms. Heart, 1920, vol. 7, p. 353-370.
    7. BENATAR, A. - DECRAENE, T. Comparison of for-mulae for heart rate correction of QT interval in exercise ECGs from healthy children. Heart, 2001, vol. 86, no. 2, p. 199-202. Go to original source... Go to PubMed...
    8. DAVIDOWSKI, TA. - WOLF, S. The QT interval during reflex cardiovascular adaptation. Circulation, 1984, vol. 69, no. 1, p. 22-25. Go to original source... Go to PubMed...
    9. FREDERICIA, LS. Die Systolendauer im Elektrokardio-gramm bei normalen Menschen und bei Herzkranken. Arch. Med. Scand., 1920, Jg. 53, S. 469-485. Go to original source...
    10. HAN, J. - GOEL, BS. Electrophysiologic precursors of ventricular tachyarrhythmias. Arch. Intern. Med., 1972, vol. 129, no. 2, p. 749-755. Go to original source... Go to PubMed...
    11. KUJANÍK, Š. - BALDOVSKÝ, Ľ. - IVANČO, I. - BAČA, M. - CZÓKOLY, V. Interval QT pri zmenách respirácie u zdravých ľudí. Bratisl. lek. Listy, 1985, roč. 84, č. 6, s. 701 až 710.
    12. KUJANÍK, Š. - VALACHOVÁ, A. - KUBÁČEK, Š. - MIKULECKÝ, M. Dependence of QT interval on the heart rate during alterations of pulmonary ventilation in young healthy subjects. Physiol. Res., 1993, vol. 42, no. 6, p. 383-389.
    13. KUJANÍK, Š. QT/QS2 pri zmenách pľúcnej ventilácie u zdravých ľudí. Noninvas. Cardiol., 1994, roč. 3, č. 3, s. 148 až 152.
    14. LEHMAN, MH. - CASE, RB. Reduced human ventricu-lar fibrillation threshold associated with contrast-induced Q-T prolongation. J. Electrocardiol., 1983, vol. 16, no. 1, p. 105-110. Go to original source... Go to PubMed...
    15. LEPESCHKIN, E. - SURAWICZ, B. The measurement of the Q-T interval of the electrocardiogram. Circulation, 1952, vol. 6, p. 378-388. Go to original source... Go to PubMed...
    16. MALIK, M. The imprecision in heart rate correction may lead to artificial observations of drug induced QT interval changes. Pacing Clin. Electrophysiol., 2002, vol. 25, no. 2, p. 209-216. Go to original source... Go to PubMed...
    17. MALIK, M. - FARBOM, P. - BATCHVAROV, V., et al. Relation between QT and RR intervals is highly individual among health subjects implications for heart rate correction of the QT interval. Heart, 2002, vol. 87, no. 3, p. 220-228. Go to original source... Go to PubMed...
    18. MIKULECKÝ, M. Základy biometriky pre experimentálnu a klinickú medicínu. Bratislava, Univerzita Komenského, 1985. 208 s.
    19. MOLNÁR, J. - WEISS, J. - ZHANG, F. - ROSENTHAL, JE. Evaluation of five QT correction formulas using a software-assisted method of continuous QT measurement from 24-hour Holter recordings. Am. J. Cardiol., 1996, vol. 78, no. 3, p. 920-926. Go to original source... Go to PubMed...
    20. MOLNÁR, J. - ZHANG, F. - WEISS, J. - EHLERT, FA. - ROSENTHAL, JE. Diurnal pattern of QTc interval: how long is prolonged? Possible relation to circadian triggers of cardiovascular events. J. Am. Coll. Cardiol., 1996, vol. 27, no. 1, p. 76-83. Go to original source... Go to PubMed...
    21. MOSS, AJ. - SCHWARTZ, PJ. Sudden death and the idio-pathic long Q-T syndrome. Am. J. Med., 1979, vol. 66, no. 1, p. 6-7. Go to original source... Go to PubMed...
    22. RAO, CR. Lineární metody statistické indukce a jejich apli-kace. (Překlad z angl.) Praha, Academia, 1978. 666 s.
    23. SCHLAMOWITZ, I. An analysis of time of relationships within the cardiac cycle in electrocardiograms of normal men. I. The duration of the Q-T interval and its relationship to the cycle length (R-R interval). Am. Heart J., 1946, vol. 31, p. 329-342. Go to original source... Go to PubMed...
    24. ŠIMEK, J. Fyziologické hodnoty u človeka. Praha, Avice-num, 1981.

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