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Frequency Domain Parameters (frequency + domain_parameter)
Selected AbstractsAutonomic dysfunction in unselected and untreated primary open angle glaucoma patients: a pilot studyOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 4 2007Doina Gherghel Abstract Purpose:, To investigate the presence of silent cardiac ischaemic episodes and the status of autonomic function in consecutive, newly diagnosed and untreated primary open-angle glaucoma patients. Methods:, Twenty-four consecutively diagnosed glaucoma patients and 22 age-matched controls were subjected to ambulatory 24-h blood pressure (BP) and electrocardiogram (ECG) monitoring by using Cardiotens-01 (Meditech Ltd). Based on the ECG recordings, heart rate variability (HRV) frequency domain parameters [low-frequency (LF), high-frequency (HF) and LF/HF ratio] were calculated and analysed in the two study groups. Results:, Glaucoma patients demonstrated higher LF and LF/HF values than normal subjects for both the active period (p = 0.020 and 0.029) and the passive period (p = 0.044 and 0.049 respectively). HRV parameters were similar in patients and controls suffering from silent cardiac ischaemia (p > 0.05); however, glaucoma patients with normal ECG demonstrated higher LF and LF/HF values during the active period of the 24-h measurement period than control subjects characterized by the same cardiac activity (p = 0.010 and 0.021 respectively). Conclusion:, Independent of a history and/or clinical signs of cardiovascular disease, glaucoma patients exhibit abnormal autonomic function. [source] Acute Effects of Moxonidine on Cardiac Autonomic ModulationPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 8 2010DAYIMI KAYA M.D. Background: Moxonidine, an imidazoline I1 receptor agonist, is a centrally acting antihypertensive agent having sympatholytic effect. However, there are only limited data regarding the effects of this drug on autonomic cardiac functions. Methods and results: In this study we investigated the acute effects of moxonidine on cardiac autonomic modulation by heart rate variability (HRV) analysis. The effects of oral 0.4-mg moxonidine were studied on 11 healthy male volunteers in a randomized, double-blind, placebo controlled, and crossover study. After 15 minutes rest, time and frequency domain parameters of HRV were calculated from 5-minute continue electrocardiography recordings in supine position, during controlled respiration (15 breath/min) and during handgrip exercise before and 1 hour after taking placebo or moxonidine. Baseline parameters before taking placebo and moxonidine were similar (P > 0.05). Moxonidine, but not placebo, caused an increase in heart failure (HF) (119 ± 21 vs 156 ± 23, P = 0.029) and HFnu (39 ± 4 vs 47 ± 4, P = 0.033) and decrease in LFnu (61 ± 4 vs 53 ± 4, P = 0.033) and LF/HF ratio (1.96 ± 0.36 vs 1.12 ± 0.35, P = 0.010) in supine position compared with baseline parameters. However, there was no difference in other time or frequency domain parameters during controlled breathing and handgrip exercise either with moxonidine or placebo administration (P > 0.05). Single dose of moxonidine administration increases cardiovagal tone but parasympathetic and sympathetic autonomic maneuvers attenuated its short term effects on HRV in healthy male subjects. (PACE 2010; 929,933) [source] Heart Rate Variability in Patients with Essential Hyperhidrosis: Dynamic Influence of Sympathetic and Parasympathetic ManeuversANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 1 2005Dayimi Kaya M.D. Background: Essential hyperhidrosis has been associated with an increased activity of the sympathetic system. In this study, we investigated cardiac autonomic function in patients with essential hyperhidrosis and healthy controls by time and frequency domain analysis of heart rate variability (HRV). Method: In this study, 12 subjects with essential hyperhidrosis and 20 healthy subjects were included. Time and frequency domain parameters of HRV were obtained from all of the participants after a 15-minute resting period in supine position, during controlled respiration (CR) and handgrip exercise (HGE) in sitting position over 5-minute periods in each stage. Results: Baseline values of HRV parameters including RR interval, SDNN and root mean square of successive R-R interval differences, low frequency (LF), high frequency (HF), normalized unit of high frequency (HFnu), normalized unit of low frequency (LFnu), and LF/HF ratio were identical in two groups. During CR, no difference was detected between the two groups with respect to HRV parameters. However, the expected increase in mean heart rate (mean R-R interval) did not occur in hyperhidrotic group, whereas it did occur in the control group (Friedman's P = 0.000). Handgrip exercise induced significant decrease in mean R-R interval in both groups and no difference was detected between the two groups with respect to the other HRV parameters. When repeated measurements were compared with two-way ANOVA, there was statistically significant difference only regarding mean heart rate in two groups (F = 6.5; P = 0.01). Conclusion: Our overall findings suggest that essential hyperhidrosis is a complex autonomic dysfunction rather than sympathetic overactivity, and parasympathetic system seems to be involved in pathogenesis of this disorder. [source] Heart Rate Variability Declines with Increasing Age and CTG Repeat Length in Patients with Myotonic Dystrophy Type 1ANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 3 2003Bradley A. Hardin Background: Cardiac myopathy manifesting as arrhythmias is common in the neurological disease, myotonic dystrophy type 1 (DM1). The purpose of the present study was to evaluate heart rate variability (HRV) in patients with DM1. Methods: In a multicenter study, history, ECG, and genetic testing were performed in DM1 patients. Results: In 289 patients in whom the diagnosis of DM1 was confirmed by a prolonged cytosine-thymine-guanine (CTG) repeat length the most common ambulatory ECG abnormality was frequent ventricular ectopy (16.3%). The 24-hour time domain parameters of SDNN (SD of the NN interval) and SDANN (SD of the mean NN, 5-minute interval) declined as age and CTG repeat length increased (SDNN: ,8.5 ms per decade, 95% confidence intervals [CI],12.9, ,4.2, ,8.7 ms per 500 CTG repeats, CI ,15.7, ,1.8, r = 0.24, P < 0.001; SDANN: ,8.1 ms per decade, CI ,12.4, ,3.8, ,8.8 ms per 500 CTG repeats, CI ,15.7, ,1.9, r = 0.23, P < 0.001). Short-term frequency domain parameters declined with age only (total power: ,658 ms2 per decade, CI: ,984, ,331, r = 0.23, P < 0.001; low frequency (LF) power ,287 ms2 per decade, CI: ,397, ,178, r = 0.30, P < 0.001; high frequency (HF) power: ,267 ms2 per decade, CI: ,386, ,144, r = 0.25, P < 0.001). The LF/HF ratio increased as the patient aged (0.5 per decade, CI: 0.1, 0.9, r = 0.13, P = 0.03). Conclusions: In DM1 patients a decline in HRV is observed as the patient ages and CTG repeat length increases. A.N.E. 2003; 8(3):227-232 [source] 2357: Autonomic nervous system and endothelial peripheral dysfunction in normal tension glaucoma patientsACTA OPHTHALMOLOGICA, Issue 2010J WIERZBOWSKA Purpose To define parameters of autonomic nervous system activity and peripheral vascular reactive hyperemia in normal tension glaucoma patients. Methods Ambulatory 24-hour electrocardiogram and blood pressure (BP) monitoring by using Lifecard CF and SpaceLab 90207-30 combined with occlusion provocation test were carried out in 54 NTG patients (44 women, mean age 59.7) and 43 matched control subjects (34 women, mean age 57.0). Heart rate variability (HRV) time and frequency domain parameters [low-frequency (LF), high-frequency (HR) and LF/HF ratio], and blood pressure variability (BPV) were calculated and analyzed for both study groups. Postocclusive hyperemia response parameters (TM - time to peak flow, TH ,half-time hyperaemia, TR ,time to rest flow, BZ-biological zero and MAX , maximum hyperemic response) were compared for patients with a nocturnal fall in mean BP (MPB) of less than 10% (non-dippers), of 10-20% (dippers) and of more than 20% (over-dippers) Results NTG patients demonstrated higher LF and LF/HF values for 24-hour period, day-time and night time than control subjects. There was no difference in BPV between study groups (10.4 ± 1.9 vs. 10.5 ± 2.1, p=0.790). In NTG patients, TH was significantly higher (79.0 ± 80.9 s vs. 51.5 ± 35.3 s, p=0.028) and BZ was significantly lower (2.3 ± 1.0 vs. 3.1 ± 2.0, p=0.009) as compared to the control group. There was statistically significant difference between NTG non-dippers, dippers and over,dippers in the BZ parameter (2.3 ± 0.9 vs. 2.7 ± 1.3 vs. 1.4 ± 0.4 p=0.024). Conclusion NTG patients exhibit abnormal ANS system activity and a different systemic hyperemia response as compared with healthy subjects. [source] | ||||||||||