title: Spectral analysis of heart rate variability before and during episodes of nocturnal ischaemia in patients with extensive coronary artery disease.
abstract: Spectral analysis of heart rate variability was used to assess autonomic nervous system activity associated with episodes of nocturnal myocardial ischaemia in 32 patients (20 men, age 58 +/- 9 years) with extensive coronary artery disease. Twenty-four hour Holter tape recordings were analysed and spectral indexes of heart rate variability were computed by fast Fourier analysis on 2 min segments covering the period from 10 min before to 10 min after each nocturnal ischaemic episode, defined as ST segment depression > or = 1 mm lasting at least 4 min. Spectral power was measured at low frequencies (LF: 0.06-0.10 Hz) and high frequencies (HF: 0.15-0.40 Hz) and the ratio LF/HF was calculated. RESULTS. A total of 30 episodes of nocturnal ischaemia were analysed. High frequency spectral power showed a clear decrease during the 10 min before the onset of ischaemia, remained steady until the end of the episode, and returned to normal by 6 min after. Low frequency spectral power fluctuated throughout the ischaemic episodes with no clear pattern of variation. The low/high frequency ratio reflected mainly the changes in high frequency. CONCLUSIONS. Sympathetic predominance due to para-sympathetic withdrawal is the principal change in autonomic nervous system activity associated with episodes of nocturnal ischaemia.
authors: Cardiology Department, University Hospital of Iraklion, Crete, Greece.
authors: P E
authors: PE
authors: Vardas
authors: G E
authors: GE
authors: Kochiadakis
authors: E G
authors: EG
authors: Manios
authors: E M
authors: EM
authors: Kanoupakis
authors: E G
authors: EG
authors: Zouridakis
authors: G I
authors: GI
authors: Chlouverakis
mesh_terms: D000368:Aged; D001341:Autonomic Nervous System / Q000503:physiopathology*; D002940:Circadian Rhythm; D003327:Coronary Disease / Q000503:physiopathology*; D015716:Electrocardiography, Ambulatory; D005260:Female; D005583:Fourier Analysis; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000503:physiopathology*; D010275:Parasympathetic Nervous System / Q000503:physiopathology; D013564:Sympathetic Nervous System / Q000503:physiopathology