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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)
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)
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)
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)
The reason for sex differences in arrhythmic risk remains unclear. Heterogeneity of ventricular repolarization is directly linked to arrhythmogenesis; thus we investigated repolarization homogeneity and its circadian pattern in men and women. During 24-h Holter recordings in 60 healthy subjects (27 males), a 12-lead electrocardiogram (ECG) was obtained(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)
Differences in APD reflect differences in ion channel properties. These properties also determine rate dependence of APD and transmural dispersion was confirmed experimentally to increase with cycle length. While several electrocardiographic indices characterising repolarisation abnormalities have been proposed, studies of their heart rate dependence are(More)
A computational study was designed to investigate the differences between the so-called study-specific and subject-specific heart rate corrections of QT interval. In 53 healthy subjects (25 women, mean age 26.7 +/- 8.7 years), serial 10-second electrocardiograms (ECG) were obtained during daytime hours. In each subject, 200 ECGs were selected representative(More)