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BACKGROUND Decreased vagal activity after myocardial infarction results in reduced heart-rate variability and increased risk of death. To distinguish between vagal and sympathetic factors that affect heart-rate variability, we used a signal-processing algorithm to separately characterise deceleration and acceleration of heart rate. We postulated that(More)
BACKGROUND To examine the relationship between reduced heart rate variability (HRV) and cognitive function in middle-aged adults in the general population. METHODS HRV, in both time and frequency domains, and cognitive functioning were measured twice in 5,375 male and female participants of the UK Whitehall II study (mean ages = 55 and 61 years,(More)
Standard time and frequency parameters of heart rate variability (HRV) describe only linear and periodic behaviour, whereas more complex relationships cannot be recognised. A method that may be capable of assessing more complex properties is the non-linear measure of 'renormalised entropy.' A new concept of the method, RE(AR), has been developed, based on a(More)
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(More)
AIMS To investigate the combination of heart rate turbulence (HRT) and deceleration capacity (DC) as risk predictors in post-infarction patients with left ventricular ejection fraction (LVEF) > 30%. METHODS AND RESULTS We enrolled 2343 consecutive survivors of acute myocardial infarction (MI) (<76 years) in sinus rhythm. HRT and DC were obtained from 24 h(More)
BACKGROUND The aim of the present study was to assess the prognostic value of novel repolarization descriptors from the 12-lead ECG in a large cohort of US veterans. METHODS AND RESULTS Male US veterans (n=813) with cardiovascular disease had digital 12-lead ECGs recorded at the VA Medical Center, Washington, DC, between 1984 and 1991. The patient series(More)
Patients with specific neurological, psychiatric or cardiovascular conditions are at enhanced risk of cardiac arrhythmia and sudden death. The neurogenic mechanisms are poorly understood. However, in many cases, stress may precipitate cardiac arrhythmia and sudden death in vulnerable patients, presumably via centrally driven autonomic nervous system(More)
Recently, it was demonstrated that the QT-RR relationship pattern varies significantly among healthy individuals. We compared the intra- and interindividual variations of the QT-RR relationship. Twenty-four-hour 12-lead digital electrocardiograms (ECGs; SEER MC, GE Marquette; 10-s ECG recorded every 30 s) were obtained at baseline and after 24 h, 1 wk, and(More)
OBJECTIVE Mental or emotional stress-induced ventricular arrhythmias and sudden cardiac death are thought to be mediated by the autonomic nervous system and ischemia. In the absence of ischemia, increased inhomogeneity of repolarization is thought to be important. We tested the hypotheses that in the absence of ischemia, mental stress may modulate(More)
Differences in action potential duration reflect differences in ion channel properties. These properties also determine rate dependence of action potential duration, and transmural dispersion was confirmed experimentally to increase with cycle length. While several electrocardiographic indexes characterizing repolarization abnormalities have been proposed,(More)