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Changes in the QT interval and its adaptation to rate, assessed with continuous electrocardiographic recordings in patients with ventricular fibrillation, as compared to normal individuals without arrhythmias

(1997) EUROPEAN HEART JOURNAL. 18(6). p.994-999
Author
Organization
Abstract
Various QT interval variables and heart rate variability parameters were studied in six patients with ventricular fibrillation but without heart disease and compared with findings in 21 normal persons. QT and QT dispersion (QTd) were measured from conventional 12 lead ECGs; for dynamic QT analysis, QT intervals were automatically measured to the end of the T wave (QTe) on a 24 h ECG recording. The adaptation of the QT interval to changes in heart rate was expressed as the slope of the linear regression lines relating QTe to the RR interval (Se). The complete 24 h ECG recording and four 6 h segments were studied (morning, day, evening, and night). Ventricular fibrillation patients had slightly prolonged QT(max) intervals on the 12 lead ECG, QT dispersion was longer in ventricular fibrillation patients than in normal persons (88 +/- 29 ms vs 59 +/- 26 ms, P<0.05), and on the 24 h ECG recording, normal persons and ventricular fibrillation patients had a comparable RR. In addition, parameters for long-term (SD, standard deviation of normal RR intervals) and short-term (RMSSD, the root-mean-square successive differences of normal RR intervals) heart rate variability were not different. Automatic measurement of the QT interval and the QTe/RR slopes was possible over 24 h and in the 6 h intervals in a large majority of patients (25/27 and 88/108 readings). The mean 24 h QT and the mean 6 h QT interval were comparable in normal subjects and ventricular fibrillation patients except for the day segment. The 24 h Se was significantly lower in ventricular fibrillation patients, compared to normal individuals. Furthermore, Se in the morning and night segment was also significantly lower in ventricular fibrillation patients (both P<0.05). In conclusion, patients with ventricular fibrillation but without underlying structural heart disease have normal heart rate variability parameters. However, abnormal repolarization behaviour, characterized by an increased QTd and a depressed adaptation of QT to variations in RR (especially during the night and the morning), is present. These findings may help to understand and treat arrhythmias in this patient group.
Keywords
autonomic nervous system, ambulatory recording, heart rate variability, QT interval, sudden death, ventricular fibrillation, HEART-RATE-VARIABILITY, MYOCARDIAL-INFARCTION, CARDIAC-ARREST, SUDDEN-DEATH, PROLONGATION, DISPERSION, REPOLARIZATION, RISK

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Chicago
Tavernier, René, Luc Jordaens, Filomeen Haerynck, E Derycke, and Denis Clement. 1997. “Changes in the QT Interval and Its Adaptation to Rate, Assessed with Continuous Electrocardiographic Recordings in Patients with Ventricular Fibrillation, as Compared to Normal Individuals Without Arrhythmias.” European Heart Journal 18 (6): 994–999.
APA
Tavernier, René, Jordaens, L., Haerynck, F., Derycke, E., & Clement, D. (1997). Changes in the QT interval and its adaptation to rate, assessed with continuous electrocardiographic recordings in patients with ventricular fibrillation, as compared to normal individuals without arrhythmias. EUROPEAN HEART JOURNAL, 18(6), 994–999.
Vancouver
1.
Tavernier R, Jordaens L, Haerynck F, Derycke E, Clement D. Changes in the QT interval and its adaptation to rate, assessed with continuous electrocardiographic recordings in patients with ventricular fibrillation, as compared to normal individuals without arrhythmias. EUROPEAN HEART JOURNAL. 1997;18(6):994–9.
MLA
Tavernier, René, Luc Jordaens, Filomeen Haerynck, et al. “Changes in the QT Interval and Its Adaptation to Rate, Assessed with Continuous Electrocardiographic Recordings in Patients with Ventricular Fibrillation, as Compared to Normal Individuals Without Arrhythmias.” EUROPEAN HEART JOURNAL 18.6 (1997): 994–999. Print.
@article{183455,
  abstract     = {Various QT interval variables and heart rate variability parameters were studied in six patients with ventricular fibrillation but without heart disease and compared with findings in 21 normal persons. QT and QT dispersion (QTd) were measured from conventional 12 lead ECGs; for dynamic QT analysis, QT intervals were automatically measured to the end of the T wave (QTe) on a 24 h ECG recording. The adaptation of the QT interval to changes in heart rate was expressed as the slope of the linear regression lines relating QTe to the RR interval (Se). The complete 24 h ECG recording and four 6 h segments were studied (morning, day, evening, and night). Ventricular fibrillation patients had slightly prolonged QT(max) intervals on the 12 lead ECG, QT dispersion was longer in ventricular fibrillation patients than in normal persons (88 +/- 29 ms vs 59 +/- 26 ms, P{\textlangle}0.05), and on the 24 h ECG recording, normal persons and ventricular fibrillation patients had a comparable RR. 
In addition, parameters for long-term (SD, standard deviation of normal RR intervals) and short-term (RMSSD, the root-mean-square successive differences of normal RR intervals) heart rate variability were not different. Automatic measurement of the QT interval and the QTe/RR slopes was possible over 24 h and in the 6 h intervals in a large majority of patients (25/27 and 88/108 readings). The mean 24 h QT and the mean 6 h QT interval were comparable in normal subjects and ventricular fibrillation patients except for the day segment. The 24 h Se was significantly lower in ventricular fibrillation patients, compared to normal individuals. Furthermore, Se in the morning and night segment was also significantly lower in ventricular fibrillation patients (both P{\textlangle}0.05). 
In conclusion, patients with ventricular fibrillation but without underlying structural heart disease have normal heart rate variability parameters. However, abnormal repolarization behaviour, characterized by an increased QTd and a depressed adaptation of QT to variations in RR (especially during the night and the morning), is present. These findings may help to understand and treat arrhythmias in this patient group.},
  author       = {Tavernier, Ren{\'e} and Jordaens, Luc and Haerynck, Filomeen and Derycke, E and Clement, Denis},
  issn         = {0195-668X},
  journal      = {EUROPEAN HEART JOURNAL},
  keyword      = {autonomic nervous system,ambulatory recording,heart rate variability,QT interval,sudden death,ventricular fibrillation,HEART-RATE-VARIABILITY,MYOCARDIAL-INFARCTION,CARDIAC-ARREST,SUDDEN-DEATH,PROLONGATION,DISPERSION,REPOLARIZATION,RISK},
  language     = {eng},
  number       = {6},
  pages        = {994--999},
  title        = {Changes in the QT interval and its adaptation to rate, assessed with continuous electrocardiographic recordings in patients with ventricular fibrillation, as compared to normal individuals without arrhythmias},
  volume       = {18},
  year         = {1997},
}