J 2008

Subject-specific profiles of QT/RR hysteresis

MALIK, Marek, Kateřina HNATKOVA, Tomáš NOVOTNÝ and G. SCHMIDT

Basic information

Original name

Subject-specific profiles of QT/RR hysteresis

Authors

MALIK, Marek (203 Czech Republic, guarantor), Kateřina HNATKOVA (203 Czech Republic), Tomáš NOVOTNÝ (203 Czech Republic, belonging to the institution) and G. SCHMIDT (276 Germany)

Edition

AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY, 2008, 0363-6135

Other information

Language

English

Type of outcome

Článek v odborném periodiku

Field of Study

30000 3. Medical and Health Sciences

Country of publisher

United States of America

Confidentiality degree

není předmětem státního či obchodního tajemství

Impact factor

Impact factor: 3.643

RIV identification code

RIV/00216224:14110/08:00059842

Organization unit

Faculty of Medicine

DOI

UT WoS

000261399900018

Keywords in English

QT adaptation; individual QT correction; electrocardiogram measurement; corrected QT variability

Tags

International impact
Změněno: 4/5/2012 14:26, Mgr. Michal Petr

Abstract

V originále

The time lag of the QT interval adaptation to heart rate changes (QT/RR hysteresis) was studied in 40 healthy subjects (18 females; mean age, 30.4 +/- 8.1 yr) with 3 separate daytime (> 13 h) 12-lead electrocardiograms (ECG) in each subject. In each recording, 330 individual 10-s ECG segments were measured, including 100 segments preceded by 2 min of heart rate varying greater than +/- 2 beats/min. Other segments were preceded by a stable heart rate. In segments preceded by variable rate, QT/RR hysteresis was characterized by lambda parameters of the exponential decay models. The intrasubject SDs of lambda values were compared with the intersubject SD of the individual means. The lambda values were also correlated to individually optimized parameters of heart rate correction. Intrasubject SDs of lambda were substantially smaller than the population SD of individual means (0.390 +/- 0.197 vs. 0.711, P < 0.0001). The lambda values were unrelated to the QT/RR correction parameters. When compared with the corrected QT (QTc) for averaged RR intervals in 10-s ECGs and with the averaged RR intervals in 2-min history, QTc for QT/RR hysteresis led to a substantially smaller SD of QTc values (11.4 +/- 2.00, 6.33 +/- 1.31, and 4.66 +/- 0.85 ms, respectively, P < 0.0001). Thus the speed with which the QT interval adapts to heart rate changes is highly individual with intrasubject stability and intersubject variability. QT/RR hysteresis is independent of the static QT/RR relationship and should be considered as a separate physiological process. The combination of individual heart rate correction with individual hysteresis correction of the QT interval is likely to lead to substantial improvements of cardiac repolarization studies.