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HRV
Kinds of HRV Terms modified by HRV Selected AbstractsCardiac autonomic function and baroreflex changes following 4 weeks of resistance versus aerobic training in individuals with pre-hypertensionACTA PHYSIOLOGICA, Issue 3 2009S. R. Collier Abstract Aim:, Cardiac autonomic modulation and baroreflex sensitivity (BRS) are altered in individuals with hypertension. Aerobic exercise (AE) training has been shown to improve both measures, yet little is known about the effects of resistance exercise (RE). The purpose of this study was to examine the heart rate variability (HRV) and BRS following 4 weeks of resistance or aerobic training in a population with borderline high blood pressure (BP). Methods:, Twenty-nine mild hypertensives were recruited and randomly assigned to 4 weeks of RE or AE training. Before and after training, resting measures of HRV frequencies and BRS were obtained. Results:, There was a significant decrease in resting systolic BP for both exercise training modes (RE 136 ± 3.0 pre- to 132 ± 3.4 post-training vs. AE 142 ± 4.0 pre- to 137 ± 3.6 mmHg post-training, P = 0.019). Diastolic BP decreased significantly following both exercise training modes (RE 78 ± 1.31 pre to 74 ± 1.1 post vs. AE 80 ± 1.7 pre to 77 ± 1.6 mmHg post, P = 0.002). A significant time by training mode interaction for low frequency : high frequency (HF) ratio (P = 0.017) with AE decreasing the ratio (275.21 ± 67.28 to 161.26 ± 61.49) and RE increasing this ratio (143.73 ± 65.00 to 227.83 ± 59.41). Natural log-transformed (ln) HRV values showed a time-by-training mode interaction for ln HF (P = 0.05) as ln HF increased (4.7 ± 0.38 to 5.4 ± 0.35 ms2) following AE and decreased (5.98 ± 0.37 to 5.76 ± 0.42 ms2) following RE. BRS increased following aerobic training and decreased after resistance training (6.74 ± 1.2 to 7.94 ± 1.3 and 10.44 ± 1.2 to 9.1 ± 1.2 ms mmHg,1 respectively, P = 0.021). Conclusions:, Aerobic exercise improved the autonomic nervous system (increasing vagal tone, reducing sympathovagal balance while increasing BRS) while RE showed no improvements in cardiac autonomic tone and decreased BRS. [source] Heart rate variability in response to pain stimulus in VLBW infants followed longitudinally during NICU stayDEVELOPMENTAL PSYCHOBIOLOGY, Issue 8 2009Nikhil S. Padhye Abstract The objective of this longitudinal study, conducted in a neonatal intensive care unit, was to characterize the response to pain of high-risk very low birth weight infants (<1,500,g) from 23 to 38 weeks post-menstrual age (PMA) by measuring heart rate variability (HRV). Heart period data were recorded before, during, and after a heel lanced or wrist venipunctured blood draw for routine clinical evaluation. Pain response to the blood draw procedure and age-related changes of HRV in low-frequency and high-frequency bands were modeled with linear mixed-effects models. HRV in both bands decreased during pain, followed by a recovery to near-baseline levels. Venipuncture and mechanical ventilation were factors that attenuated the HRV response to pain. HRV at the baseline increased with post-menstrual age but the growth rate of high-frequency power was reduced in mechanically ventilated infants. There was some evidence that low-frequency HRV response to pain improved with advancing PMA. © 2009 Wiley Periodicals, Inc. Dev Psychobiol 51: 638,649, 2009 [source] Characteristic patterns of circadian variation in plasma catecholamine levels, blood pressure and heart rate variability in Type 2 diabetic patientsDIABETIC MEDICINE, Issue 5 2002K. Kondo Abstract Aims To investigate whether Type 2 diabetic patients exhibit characteristic patterns of circadian variation in plasma levels of catecholamines, blood pressure (BP) and heart rate variability (HRV). Methods Ten Type 2 diabetic and eight control in-patients were studied. Blood for catecholamine measurement was collected every 4 h, and non-invasive ambulatory BP and heart rate were monitored throughout the day. HRV was determined using frequency domain methods. Results Diabetic patients showed a different pattern of circadian variation in BP and HRV from that of controls, the diurnal-nocturnal differences (D-N) being significantly smaller. The mean 24-h HRV levels were reduced in diabetic subjects. The mean 24-h plasma noradrenaline level of 1.36 ± 0.12 nmol/l in diabetic patients was significantly lower than the 2.03 ± 0.20 nmol/l in controls (P < 0.01). In contrast, no significant difference in adrenaline levels was observed. The mean 24-h plasma noradrenaline level demonstrated a significant positive correlation with D-N in systolic BP (r = 0.49, P = 0.0153). Conclusions The present study demonstrated distinctive patterns of circadian variation in plasma noradrenaline level, BP and HRV in Type 2 diabetic patients, associated with an abnormal circadian pattern of sympathovagal modulation. [source] Low prevalence of cardiac autonomic neuropathy in Type 1 diabetic patients without nephropathyDIABETIC MEDICINE, Issue 8 2001J. A. Meinhold Abstract Aim To assess the prevalence of cardiac autonomic neuropathy (CAN) in Type 1 diabetic patients with and without nephropathy. Methods Sixty-six consecutive patients without nephropathy (n = 24), with incipient (n = 26) or overt nephropathy (n = 16) and a diabetes duration between 21 and 31 years were examined. Heart rate variability (HRV) as measure for CAN was investigated with short-term spectral analysis in the low-frequency (LF) band (0.06,0.15 Hz), reflecting sympathetic and vagal activity, and high-frequency (HF) band (0.15,0.50 Hz), reflecting vagal activity. HRV was expressed as spectral power (ms2, log-transformed). Normal, age-corresponding reference values were established in 184 controls. QTc intervals and dispersion were measured. Results After adjustment for age, there was no significant difference between healthy controls and patients without nephropathy. After further adjustment for diabetes duration, HbA1c, hypertension and treatment with ,-blockers, HRV in both frequency bands decreased with evidence of nephropathy. LF band (supine): patients without nephropathy 5.56 (4.89,6.21) (least squares means and 95% confidence interval (CI)), incipient nephropathy 5.72 (5.15,6.29) and overt nephropathy 4.11 (3.27,4.96). HF band (supine): without nephropathy 5.93 (5.26,6.60), incipient nephropathy 5.99 (5.41,6.57) and overt nephropathy 4.84 (4.00,5.68). Significant differences were found for patients without and with incipient nephropathy compared with those with overt nephropathy in the LF band and between patients with incipient nephropathy compared with those with overt nephropathy in the HF band. QTc intervals and QTc dispersion increased significantly with increasing nephropathy. Conclusions Long-term Type 1 diabetes without nephropathy was not associated with impaired cardiac autonomic function in our study. However, in those with nephropathy, a loss of both vagal and sympathetic activity was present, and the severity of CAN correlated positively with more advanced nephropathy. Diabet. Med. 18, 607,613 (2001) [source] Viral proteinases: targets of opportunityDRUG DEVELOPMENT RESEARCH, Issue 6 2006Chelsea M. Byrd Abstract During antiviral drug development, any essential stage of the viral life cycle can serve as a potential drug target. Since most viruses encode specific proteases whose cleavage activity is required for viral replication, and whose structure and activity are unique to the virus and not the host cell, these enzymes make excellent targets for drug development. Success using this approach has been demonstrated with the plethora of protease inhibitors approved for use against HIV. This discussion is designed to review the field of antiviral drug development, focusing on the search for protease inhibitors, while highlighting some of the challenges encountered along the way. Protease inhibitor drug discovery efforts highlighting progress made with HIV, HCV, HRV, and vaccinia virus as a model system are included. Drug Dev. Res. 67:501,510, 2006. © 2006 Wiley-Liss, Inc. [source] Effect of detergent on electromigration of proteins: CE of very low density lipoprotein receptor modules and viral proteinsELECTROPHORESIS, Issue 20 2007Leopold Kremser Dr. Abstract The different electrophoretic behavior of the members of two groups of proteins with respect to the absence or presence of detergent additives in the BGE was explored. Recombinant soluble concatemers of repeat 3 of the very low density lipoprotein (VLDL)-receptor fused at their N -terminus to maltose-binding protein (MBP) exhibited different electrophoretic mobilities in borate buffer (pH,8.3) in the absence and in the presence of dodecyl-PEG ether (D-PEG). This enabled the separation of the receptor fragments from MBP after enzymatic cleavage. In the presence of SDS, the mobilities of all proteins approached the same values with increase in detergent concentrations. In contrast, viral capsid proteins of a human rhinovirus (HRV) exhibited different migration in the presence of the additive. For the receptor proteins, extreme apparent high plate numbers were observed when the SDS concentration in the sample and the separation buffer differed. This effect might be erroneously interpreted as a high efficiency. However, it is due to the conductivity boundaries caused by the sample and leads to a total loss of separation. [source] Circadian Variation in Heart-Rate Variability in Localization-related EpilepsyEPILEPSIA, Issue 5 2007Hĺkan Persson Summary:,Purpose: Case,control studies of sudden unexpected death in epilepsy (SUDEP) have reported that SUDEP is more likely to occur during sleep and thus presumably during night hours. The circadian variation of heart-rate variability (HRV) might be of relevance to this risk. We examined night versus daytime HRV in patients with newly diagnosed and refractory localization-related epilepsy, assessing the effects of drug treatment and epilepsy surgery on the night/daytime HRV ratio. Methods: We used spectral analysis to assess HRV and calculated the night-time (00.00,05.00)/daytime (07.30,21.30) ratio of HRV in 14 patients with newly diagnosed localization-related epilepsy before and during carbamazepine (CBZ) treatment and in 21 patients with temporal lobe epilepsy before and after epilepsy surgery. Both groups were compared with age- and sex-matched controls. Results: No significant differences were found from controls in the night/daytime ratios of HRV whether compared before or after initiation of treatment with CBZ in newly diagnosed epilepsy patients. When patients were used as their own controls, night/daytime ratios of standard deviation of RR intervals (p = 0.04) and total power (p = 0.04) were significantly lower during treatment than before. Compared with those of controls, the night/daytime ratios were lower in epilepsy surgery patients before surgery [low-frequency power (p = 0.04); high-frequency power (p = 0.04)]. Night/daytime ratios did not change significantly after surgery. Conclusions: The HRV of the patients was more affected during night-time when the risk of SUDEP seems to be highest in such patients. [source] Cardiac Dysrhythmia Associated with the Immediate Postictal State after Maximal Electroshock in Freely Moving RatEPILEPSIA, Issue 4 2002Olivier Darbin Summary: ,Purpose: Cardiac autonomic changes accompany complex partial seizures and generalized tonic,clonic seizures, and participate, at least partially, in the sudden and unexpected death in epilepsy (SUDEP). The analysis of the heart rate variability (HRV) is one of the simplest ways of providing insight into autonomic functions. The entropy quantifies the repetition of complex patterns in a signal and refers to systems randomness, regularity, and predictability. Clinical investigations have reported that entropy decreases in patients with a high risk of sudden cardiac death. The goal of this study was to evaluate the effects of the maximal electroshock (MES) on the entropy of HRV, monitored in the immediate postictal stage in the model of the freely moving rat. Methods: Entropy changes were correlated with the high and low frequencies of spectral analysis, which reflect the participation of the sympathetic and parasympathetic activities. Results: MES-induced arrhythmia is characterized by an HRV increase, an imbalance in favor of the parasympathetic activity, and a decrease in the entropy. Entropy decrease was restricted to the duration of the arrhythmia, suggesting that the postictal arrhythmia may be associated with a higher risk of lethal cardiac complications. Nevertheless, entropy changes did not correlate with spectral changes. Conclusions: The results suggest that the imbalance demonstrated in the spectral domain explains only partially the contribution of each autonomic system in the complexity of the heart rate during the postictal state. [source] Impact of body fat mass extent on cardiac autonomic alterations in womenEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 8 2009J. Sztajzel Abstract Background, Obesity has been associated with significant abnormalities of the cardiac autonomic regulation. However, the precise impact of increasing body weight on cardiac autonomic function and the metabolic and hormonal contributors to these changes are presently unclear. The aim of our study was to explore in subjects with increasing values of body mass index (BMI) the alterations of cardiac autonomic function and to establish the potential role of various metabolic and hormonal contributors to these alterations. Materials and methods, We investigated time and frequency domain heart rate variability (HRV) parameters taken from 24-h Holter recordings, and several anthropometric, metabolic and hormonal parameters (plasma glucose, insulin, triglycerides, free fatty acids, leptin and adiponectin) in 68 normoglycaemic and normotensive women (mean age of 40 ± 3 years), subdivided according to their BMI into 15 normal body weight (controls), 15 overweight, 18 obese and 20 morbidly obese. Results, Heart rate was increased and HRV was decreased in the morbidly obese group as compared with controls. In overall population, a negative association linked body fat mass (FM) to HRV indices. None of the metabolic and hormonal parameters were significantly related to the HRV indices, after they were adjusted for the body FM. Conclusions, Morbidly obese, normoglycaemic and normotensive young women have increased HR and low HRV, indicating an abnormal cardiac autonomic function and representing a risk factor for adverse cardiovascular events. A decrease of HRV parameters is associated with a progressive increase of body FM. Other metabolic and hormonal factors, characterising obesity, do not show an independent influence on these HRV alterations. [source] Effect of intensive training on heart rate variability in prepubertal swimmersEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 10 2005A. Vinet Abstract Background, In children, there is very limited evidence focusing on the beneficial effect of exercise training on heart rate variability (HRV) during childhood. Despite the fact that more and more children are engaged in intensive training programs, the question arises if such intensive training involves deleterious effects on the cardiac autonomic nervous system during childhood. Thus the aim of the present study was to compare HRV parameters in highly trained swimmer boys and untrained counterparts. Methods, Twenty prepubertal boys, aged 11,12 years old, took part in the study. The children were divided into 11 highly trained prepubertal swimmers (training sessions of 8,10 h weekly for at least 4 years) and 9 age-matched active boys. HRV analysis was performed on diurnal recordings in the frequency (short-term recordings 6 min the most ,vagal') and time (long-term recordings 4 h centred on the 6 min most ,vagal') domains. Results, No significant differences were obtained between groups for all frequency variables whatever the mode of expression (absolute in ms2, relative in Ln or %). All time-domain components were not significantly different in swimmers and untrained boys. Conclusions, The results of the present study demonstrate that participating intensively in swimming training does not induce in children changes in HRV indices. Neither time nor domain HRV variables were significantly different between untrained and highly trained prepubertal boys. Thus, intensive training in healthy children does not involve deleterious effects on HRV. [source] Effects of glucose ingestion on cardiac autonomic nervous system in healthy centenarians: differences with aged subjectsEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 4 2000Paolisso Background Spectral analysis of heart rate variability (HRV) investigates the cardiac autonomic nervous system (ANS) activity. In particular, low frequency/high frequency (LF/HF) is considered an index of cardiac sympatho-vagal balance and is stimulated by glucose ingestion in healthy subjects. No studies have evaluated the effect of glucose ingestion on cardiac ANS in centenarians. Materials and methods In 30 healthy centenarians (HC) and 25 aged subjects (AS) power spectral analysis of HRV was investigated during an oral glucose ingestion. Results Glucose ingestion rose LF/HF ratio in both groups studied. Such stimulatory effects were restrained to the first 60 min of the study. Independent of age, gender, body mass index (BMI) and fasting plasma norepinephrine and FT3 concentrations, HC had basal total power (1318 ± 546 vs. 1918 ± 818 msec2, P < 0.01), lower low frequency (LF) (33 ± 21 vs. 50 ± 11 n.u. , P < 0.03), and higher high frequency (HF) (74 ± 18 vs. 43 ± 15 n.u., P < 0.05) than AS. Consequently, LF/HF ratio (0.43 ± 0.07 vs. 0.91 ± 0.05, P < 0.02) was also lower in HC than in AS. In AS, but not in HC, the baseline LF/HF ratio correlated significantly with BMI (r = 0.48, P < 0.01), waist-hip-ratio (WHR) (r = 0.45, P < 0.02), fasting plasma insulin (r = 0.49, P < 0.01) and norepinephrine (r = 0.57, P < 0.02) concentration. Glucose ingestion was associated with a significant rise in LF/HF ratio in both groups studied but per cent changes in glucose mediated stimulation of LF/HF was lower in HC than in AS. In a control study, water administration did not affect power spectral parameters of HRV. Conclusion Our study demonstrates that basal- and glucose-stimulated LF/HF, an indirect index of cardiac sympatho-vagal balance, are lower in HC than in AS. [source] Heart rate variability in beta-thalassemia patientsEUROPEAN JOURNAL OF HAEMATOLOGY, Issue 5 2009Wasarut Rutjanaprom Abstract Background:, Cardiac failure remains the major cause of death in beta-thalassemia major (TM). Reduced heart rate variability (HRV) is associated with a higher risk of arrhythmias after myocardial infarction and heart failure. We evaluated HRV in TM patients and its relationship with hemodynamics and echocardiographic parameters during a 6-month follow-up. Methods:, Thirty-four TM patients (19 ± 10 yr) and 20 healthy subjects (17 ± 6 yr) were evaluated. Hematologic, biochemical, echocardiographic and HRV parameters were determined at entry and at 6-month follow-up. Time and frequency domain HRV parameters were analyzed from 24-h recorded electrocardiograms. All TM patients received blood transfusion and chelation therapy. Results:, Both time and frequency domain HRV parameters were markedly reduced in TM patients, compared to the control. The significantly improved HRV was seen in correlation with higher hemoglobin (Hb) level when compared within TM group at different time point. No correlation was seen between HRV and serum ferritin, reactive oxygen species (ROS) and non-transferrin bound iron (NTBI). Conclusion:, HRV is depressed in TM patients. HRV was significantly correlated with Hb level, suggesting that anemia greatly influences the cardiac autonomic balance. [source] Heart Rate Variability in Emergency Department Patients with SepsisACADEMIC EMERGENCY MEDICINE, Issue 7 2002Douglas Barnaby MD Abstract Objective: To test the hypothesis that heart rate variability (HRV) can provide an early indication of illness severity among patients presenting to the emergency department (ED) with sepsis. Methods: The authors enrolled a convenience sample of 15 ED patients meeting the American College of Chest Physicians/Society of Critical Care Medicine criteria for sepsis. Each patient had continuous Holter monitoring performed in the ED. Acute Physiology and Chronic Health II (APACHE II) and Sequential Organ Failure (SOFA) scores were calculated for the day of presentation. Holter tapes obtained in the ED were analyzed off-line to calculate HRV variables for the 5-minute segment with the least artifact and non-sinus beats. These variables were correlated with APACHE II and SOFA scores. Results: LFnu (normalized low-frequency power), an assessment of the relative sympathetic contribution to overall HRV, was correlated with increased illness severity as calculated using APACHE II (r = -0.67, r2= 0.43) and SOFA (r = -0.80, r2= 0.64) scores. LF/HF ratio (low-frequency/high-frequency ratio), a measure of sympathovagal balance, was correlated with the SOFA score [r = -0.54 (95% CI = -0.83 to -0.01), r2= 0.29]. All five patients who required critical care monitoring or ventilatory support or who died during the first 5 days of their hospitalization had LFnu values below 0.5 and LF/HF ratios less than 1.0. None of the patients with measurements greater than these threshold values died or required these interventions during the five days following admission. Conclusions: A single variable, LFnu, which reflects sympathetic modulation of heart rate, accounted for 40-60% of the variance in illness severity scores among patients presenting to the ED with sepsis. HRV, as reflected in LFnu and the LF/HF ratio and measured with a single brief (5-minute) period of monitoring while in the ED, may provide the emergency physician with a readily available, noninvasive, early marker of illness severity. The threshold effect of LFnu and LF/HF in the prediction of early clinical deterioration was an unexpected finding and should be regarded as hypothesis-generating, pending further study. [source] Effect of deep brain stimulation of the posterior hypothalamic area on the cardiovascular system in chronic cluster headache patientsEUROPEAN JOURNAL OF NEUROLOGY, Issue 9 2007P. Cortelli The objective of this study was to determine the cardiovascular effects of chronic stimulation of the posterior hypothalamic area (PHA) in cluster headache (CH) patients. Systolic and diastolic blood pressure (SBP, DBP), cardiac output, total peripheral resistance (TPR), heart rate (HR) and breathing were monitored at supine rest and during head-up tilt test (HUTT), Valsalva manoeuvre, deep breathing, cold face test and isometric handgrip in eight drug-resistant chronic CH patients who underwent monolateral electrode implantation in the PHA for therapeutic purposes. Autoregressive power spectral analysis (PSA) of HR variability (HRV) was calculated at rest and during HUTT. Each subject was studied before surgery (condition A) and after chronic deep brain stimulation (DBS) of PHA (condition B). Baseline SBP, DBP, HR and cardiovascular reflexes were normal and similar in both conditions. With respect to condition A, DBP, TPR and the LF/HF obtained from the PSA of HRV were significantly (P < 0.05) increased during HUTT in condition B. In conclusion, chronic DBS of the PHA in chronic CH patients is associated with an enhanced sympathoexcitatory drive on the cardiovascular system during HUTT. [source] Body Position and Cardiac Dynamic and Chronotropic Responses to Steady-State Isocapnic Hypoxaemia in HumansEXPERIMENTAL PHYSIOLOGY, Issue 2 2000S. Deborah Lucy Neural mediation of the human cardiac response to isocapnic (IC) steady-state hypoxaemia was investigated using coarse-graining spectral analysis of heart rate variability (HRV). Six young adults were exposed in random order to a hypoxia or control protocol, in supine and sitting postures, while end-tidal PCO2 (PET,CO2) was clamped at resting eucapnic levels. An initial 11 min period of euoxia (PET,O2 100 mmHg; 13.3 kPa) was followed by a 22 min exposure to hypoxia (PET,O2 55 mmHg; 7.3 kPa), or continued euoxia (control). Harmonic and fractal powers of HRV were determined for the terminal 400 heart beats in each time period. Ventilation was stimulated (P < 0.05) and cardiac dynamics altered only by exposure to hypoxia. The cardiac interpulse interval was shortened (P < 0.001) similarly during hypoxia in both body positions. Vagally mediated high-frequency harmonic power (Ph) of HRV was decreased by hypoxia only in the supine position, while the fractal dimension, also linked to cardiac vagal control, was decreased in the sitting position (P < 0.05). However, low-frequency harmonic power (Pl) and the HRV indicator of sympathetic activity (Pl/Ph) were not altered by hypoxia in either position. These results suggest that, in humans, tachycardia induced by moderate IC hypoxaemia (arterial O2 saturation Sa,O2, 85%) was mediated by vagal withdrawal, irrespective of body position and resting autonomic balance, while associated changes in HRV were positionally dependent. [source] Electrophysiological study of infant and adult rats under acute intoxication with fluoroacetamideJOURNAL OF APPLIED TOXICOLOGY, Issue 6 2007Sergey V. Kuznetsov Abstract A study was conducted of acute intoxication of infant and adult Wistar rats with fluoroacetamide (FAA), an inhibitor of oxidative metabolism. FAA was administered orally to adult rats at 1/2 LD50 and subcutaneously to infant rats at LD100 or 1/10 LD50. Electrocardiogram (ECG), respiration and motor activity were registered for 7 days. Clinical analysis of ECG and the heart rate variability (HRV) was carried out to assess the state of the vegetative nervous system. In adult rats, FAA caused marked disturbances in the activity of cardiovascular and respiratory systems, including the development of a potentially lethal acute cor pulmonale. Conversely, there were no significant changes of cardiac function and respiration in infant rats; they died because of extreme emaciation accompanied by retardation of development. In adult rats, bursts of associated cardiac and respiratory tachyarrhythmia, as well as regular high amplitude spasmodic sighs having a deca-second rhythm were observed. In both infant and adult rats, FAA caused short-term enhancement of humoral (metabolic) and sympathetic activities, followed by a gradual and stable predominance of parasympathetic influence on HRV. Under conditions of FAA inhibition of the tricarboxylic acid cycle, the observed physiological reactions may be explained by activation of alternative metabolic pathways. This is also supported by a lack of ontogenetically caused inhibition of spontaneous motor activity in infant rats poisoned with FAA, which highlights the significance of the alternative metabolic pathways for implementation of deca-second and minute rhythms and a lack of a rigid dependence of these rhythms upon activity of neuronal networks. Copyright © 2007 John Wiley & Sons, Ltd. [source] Cardiac Resynchronization Therapy Upregulates Cardiac Autonomic ControlJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 10 2008YONG-MEI CHA M.D. Objective: To determine the effect of cardiac resynchronization therapy (CRT) on sympathetic nervous function in heart failure (HF). Background: Neurohormonal dysregulation and cardiac autonomic dysfunction are associated with HF and contribute to HF progression and its poor prognosis. We hypothesized that mechanical resynchronization improves cardiac sympathetic function in HF. Methods: Sixteen consecutive patients receiving CRT for advanced cardiomyopathy and 10 controls were included in this prospective study. NYHA class, 6-minute walk distance, echocardiographic parameters, plasma norepinephrine (NE) were assessed at baseline, 3-month and 6-month follow-up. Cardiac sympathetic function was determined by 123iodine metaiodobenzylguanidine (123I-MIBG) scintigraphy and 24-hour ambulatory electrocardiography. Results: Along with improvement in NYHA class (3.1 ± 0.3 to 2.1 ± 0.4, P < 0.001) and LVEF (23 ± 6% to 33 ± 12%, P < 0.001), delayed heart/mediastinum (H/M) 123I-MIBG ratio increased significantly (1.8 ± 0.7 to 2.1 ± 0.6, P = 0.04) while the H/M 123I-MIBG washout rate decreased significantly (54 ± 25% to 34 ± 24%, P = 0.01) from baseline to 6-month follow-up. The heart rate variability (HRV) measured in SD of normal-to-normal intervals also increased significantly from baseline (82 ± 30 ms) to follow-up (111 ± 32 ms, P = 0.04). The improvement in NYHA after CRT was significantly associated with baseline 123I-MIBG H/M washout rate (r = 0.65, P = 0.03). The improvement in LVESV index was associated with baseline 123I-MIBG delayed H/M ratio (r =,0.67, P = 0.02) and H/M washout rate (r = 0.65, P = 0.03). Conclusion: After CRT, improvements in cardiac symptoms and LV function were accompanied by rebalanced cardiac autonomic control as measured by 123I-MIBG and HRV. [source] Nonlinear Indices of Heart Rate Variability in Chronic Heart Failure Patients: Redundancy and Comparative Clinical ValueJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 4 2007ROBERTO MAESTRI M.S. Aims: We aimed to assess the mutual interrelationships and to compare the prognostic value of a comprehensive set of nonlinear indices of heart rate variability (HRV) in a population of chronic heart failure (CHF) patients. Methods and Results: Twenty nonlinear HRV indices, representative of symbolic dynamics, entropy, fractality-multifractality, predictability, empirical mode decomposition, and Poincaré plot families, were computed from 24-hour Holter recordings in 200 stable CHF patients in sinus rhythm (median age [interquartile range]: 54 [47,58] years, LVEF: 23 [19,28]%, NYHA class II,III: 88%). End point for survival analysis (Cox model) was cardiac death or urgent transplantation. Homogeneous variables were grouped by cluster analysis, and in each cluster redundant variables were discarded. A prognostic model including only known clinical and functional risk factors was built and the ability of each selected HRV variable to add prognostic information to this model assessed. Bootstrap resampling was used to test the models stability. Four nonlinear variables showed a correlation >0.90 with classical linear ones and were discarded. Correlations >0.80 were found between several nonlinear variables. Twelve clusters were obtained and from each cluster a candidate predictor was selected. Only two variables (from empirical mode decomposition and symbolic dynamics families) added prognostic information to the clinical model. Conclusion: This exploratory study provides evidence that, despite some redundancies in the informative content of nonlinear indices and strong differences in their prognostic power, quantification of nonlinear properties of HRV provides independent information in risk stratification of CHF patients. [source] Sometimes Higher Heart Rate Variability Is Not Better Heart Rate Variability: Results of Graphical and Nonlinear AnalysesJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 9 2005PHYLLIS K. STEIN Ph.D. Objective: To determine the prevalence and effect on traditional heart rate variability (HRV) indices of abnormal HRV patterns in the elderly. Methods: Hourly Poincaré plots and plots of spectral HRV from normal-to-normal interbeat intervals and hourly nonlinear HRV values were examined in a subset of 290 consecutive participants in the Cardiovascular Health Study. Only subjects in normal sinus rhythm with ,18 hours of usable data were included. Eligible subjects were 71 ± 5 years. During 7 years of follow-up, 21.7% had died. Hours were scored as normal (0), borderline (0.5), or abnormal (1) from a combination of plot appearance and HRV. Summed scores were normalized to 100% to create an abnormality score (ABN). Short-term HRV versus each 5th percentile of ABN was plotted and a cutpoint for markedly increased HRV identified. The t -tests compared HRV for subjects above and below this cutpoint. Cox regression evaluated the association of ABN and mortality. Results: Of 5,815 eligible hourly plots, 64.4% were normal, 14.5% borderline, and 21.1% abnormal. HR, SDNN, SDNNIDX, ln VLF and LF power, and power law slope did not differ by the cutpoint for increased short-term HRV, while SDANN and ln ULF power were significantly lower for those above the cutpoint. However, many HRV indices including LF/HF ratio and normalized LF and HF power were significantly different between groups (P < 0.001). Increased ABN was significantly associated with mortality (P = 0.019). Despite similar values for many HRV indices, being in the group above the cutpoint was significantly associated with mortality (P = 0.04). Conclusions: Abnormal HR patterns that elevate many HRV indices are prevalent among the elderly and associated with higher risk of mortality. Consideration of abnormal HRV may improve HRV-based risk stratification. [source] Relationship Between Heart Rate Turbulence and Heart Rate, Heart Rate Variability, and Number of Ventricular Premature Beats in Coronary PatientsJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 7 2004IWONA CYGANKIEWICZ M.D., Ph.D. Introduction: Heart rate variability (HRV) illustrates regulation of the heart by the autonomic nervous system whereas heart rate turbulence (HRT) is believed to reflect baroreflex sensitivity. The aim of this study was to determine the association between HRT and HRV parameters and the relationship between HRT parameters and heart rate and number of ventricular premature beats (VPBs) used to calculate HRT parameters. Methods and Results: In 146 patients (117 males and 29 females; mean age 62 years) with coronary artery disease, a 24-hour ECG Holter monitoring was performed to calculate mean heart rate (RR interval), number of VPBs, time- and frequency-domain HRV parameters and two HRT parameters: turbulence onset (TO) and turbulence slope (TS). Univariate and multivariate regression analyses were performed to evaluate the association between tested parameters. Significant correlation between TS and mean RR interval was observed (r = 0.42; p < 0.001), while no association for TO vs. RR interval was found. TS values were significantly higher in patients with less than 10 VPBs/24 hours than in patients with more frequent VPBs. Significant associations between HRT and HRV parameters were found with TS showing stronger correlation with HRV parameters than TO (r value ranging from 0.35 to 0.62 for TS vs. ,0.16 to ,0.38 for TO). Conclusion: HRT parameters correlate strongly with HRV parameters indicating that HRT should be considered as a reflection of both baroreceptors response and overall autonomic tone. Heart rate dependence of turbulence slope indicates the need to adjust this parameter for heart rate. (J Cardiovasc Electrophysiol, Vol. 15, pp. 731-737, July 2004) [source] Circadian Profile of Cardiac Autonomic Nervous Modulation in Healthy Subjects:JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 8 2003Differing Effects of Aging, Gender on Heart Rate Variability Introduction: Although heart rate variability (HRV) has been established as a tool to study cardiac autonomic activity, almost no data are available on the circadian patterns of HRV in healthy subjects aged 20 to 70 years. Methods and Results: We investigated 166 healthy volunteers (81 women and 85 men; age 42 ± 15 years, range 20,70) without evidence of cardiac disease. Time-domain HRV parameters were determined from 24-hour Holter monitoring and calculated as hourly mean values and mean 24-hour values. All volunteers were fully mobile, awoke around 7 A.M., and had 6 to 8 hours of sleep. Circadian profiles of vagus-associated HRV parameters revealed a marked day-night pattern, with a peak at nighttime and a plateau at daytime. The characteristic nocturnal peak and the day-night amplitude diminished with aging by decade. Estimates of overall HRV (geometric triangular index [TI], SD of NN intervals [SDNN]) and long-term components of HRV (SD of the averages of NN intervals for all 5-min segments [SDANN]) were low at nighttime and increased in the morning hours. There was a significant decline of 24-hour values of all HRV parameters (P < 0.001) and a strong negative correlation (P < 0.001) with increasing age. Mean 24-hour RR interval (P < 0.001), SDNN, mean SD of NN intervals for all 5-minute intervals (SDNNi), and SDANN (all P < 0.01) were significantly higher in men. Younger men also exhibited significantly higher values for vagus-associated parameters (root mean square successive difference [rMSSD], P < 0.05; SDNNi, P < 0.01); however, gender differences diminished with increasing age. Conclusion: Normal aging is associated with a constant decline of cardiac vagal modulation due to a significant decrease of nocturnal parasympathetic activity. The significant gender-related difference of HRV decreases with aging. These findings emphasize the need to determine age-, gender-, and nycthemeral-dependent normal ranges for HRV assessment. (J Cardiovasc Electrophysiol, Vol. 14, pp. 791-799, August 2003) [source] Role of Autonomic Tone in the Initiation and Termination of Paroxysmal Atrial Fibrillation in Patients Without Structural Heart DiseaseJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 6 2003Takeshi Tomita M.D. Introduction: Previous studies have suggested that paroxysmal atrial fibrillation (PAF) of vagal origin often occurs at night and PAF of sympathetic origin occurs during the daytime; however, autonomic tone after spontaneous termination of PAF has not been determined. The aim of this study was to evaluate by heart rate variability (HRV) analysis the relationship between the time of PAF onset and autonomic tone before and after PAF. Methods and Results: Twenty-three patients (65 ± 2years) who underwent 24-hour ambulatory monitoring, had one or more episodes of PAF (>30 min), and had maintained normal sinus rhythm for >60 min before/after PAF were enrolled in this study. Mean duration of PAF was6.2 ± 1.2hours. HRV parameters were analyzed in a 10-minutes section at 60 minutes, 20 minutes, and immediately before the onset of PAF and after its termination. PAF began at night in 14 patients (group N) and during the daytime in 9 patients (group D). In group N, the high-frequency (HF) component and low-frequency (LF) component showed a significant decrease after PAF; PAF was preceded by a gradual increase in HF and LF. Changes in the LF/HF ratio, however, did not occur before or after PAF. Conversely, group D showed a significant increase in the LF/HF ratio before PAF and a decrease in LF and the LF/HF ratio after PAF, but no changes in HF. These changes in HRV parameters were not influenced by the duration or termination time of PAF. Conclusion: This study suggests that the autonomic nervous system plays an important role in both the initiation and termination of PAF. Furthermore, the time of PAF onset influences the autonomic tone at the initiation and termination of PAF. (J Cardiovasc Electrophysiol, Vol. 14, pp. 559-564, June 2003) [source] Interleukin-6 Levels are Inversely Correlated with Heart Rate Variability in Patients with Decompensated Heart FailureJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 3 2001DORON ARONSON M.D. Interleukin-6 and Heart Rate Variability.Introduction: Increased local and systemic elaboration of cytokines have an important role in the pathogenesis of congestive heart failure (CHF) through diverse mechanisms. Because cytokines are known to act at the neuronal level in both the peripheral and central nervous system, we sought to determine whether increased cytokine levels are associated with the autonomic dysfunction that characterizes CHF. Methods and Results: We studied 64 patients admitted for decompensated CHF (mean age 59 ± 12 years). Autonomic function was assessed using time, and frequency-domain heart rate variability (HRV) measures, obtained from 24-hour Holter recordings. In addition, norepinephrine, tumor necrosis factor-, (TNF-,), and interleukin-6 (IL-6) were measured in all patients. TNF-, levels did not correlate with any of the HRV measures. IL-6 inversely correlated with the time-domain parameters of standard deviation of RR intervals (SDNN) (r =,0.36, P = 0.004) and standard deviation of all 5,minute mean RR intervals (SDANN) (r =,0.39, P = 0.001), and with the frequency-domain parameters of total power (TP) (r =,0.37, P = 0.003) and ultralow-frequency (ULF) power (r =,0.43, P = 0.001). No correlation was found between IL-6 and indices of parasympathetic modulation. Using multiple linear regression models, adjusting for clinical variables and drug therapies, the strong inverse relationship between IL-6 and SDNN (P = 0.006), SDANN (P = 0.001), TP (P = 0.04), and ULF power (P = 0.0007) persisted. Conclusion: Reduction of long-term HRV indices is associated with increased levels of IL-6 in patients with decompensated heart failure. The ability of long-term HRV parameters to better reflect activation of diverse hormonal systems may explain their greater prognostic power for risk stratification in patients with CHF. [source] Gender-Related Differences in Modulation of Heart Rate in Patients with Congestive Heart FailureJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 10 2000DORON ARONSON M.D. Gender and HRV in Heart Failure Introduction. The prognosis of women with congestive heart failure (CHF) is better than that for men, but the mechanisms underlying the female survival advantage are not well understood. CHF is characterized by profound abnormalities in cardiac autonomic control that contribute to progressive circulatory failure and influence survival. Methods and Results. Time- and frequency-domain heart rate variability (HRV) indexes were obtained from 24-hour Holter recordings and compared to assess the role of gender in 131 men and 68 women with CHF (mean age 60 ± 13.6 years, range 21 to 87; New York Heart Association Functional Class III [66%] and IV [34%]). Gender-related differences in HRV were observed only in the subset of patients with nonischemic heart failure (55 men and 39 women). Among the time-domain indexes, the SD of the RR intervals (76 ± 5.3 msec vs 55.3 ± 3.2 msec, P < 0.0001) and indexes denoting parasympathetic modulation, the percentage of RR intervals with >50 msec variation (4.0%± 1.0% vs 6.5%± 1.3%, P = 0.02), and the square root of mean squared differences of successive RR intervals (19.1 ± 3.3 vs 28.4 ± 3.8, P = 0.004) were higher in women. Among the frequency-domain indexes, the total power (7.5 ± 0.13 In-msec2 vs 8.3 ± 0.14 In-msec2, P = 0.0002), the ultralow-frequency power (7.2 ± 0.11 In-msec2 vs 8.0 ± 0.14 In-msec2, P < 0.0001), the low-frequency power (3.8 ± 0.25 In-msec2 vs 4.8 ± 0.28 In-msec2, P = 0.006), and the high-frequency power (3.8 ± 0.24 In-msec2, vs 4.6 ± 0.26 In-msec2, P = 0.003) were greater in women than in men. Conclusion. Women with nonischemic CHF have an attenuated sympathetic activation and parasympathetic withdrawal compared with men. Gender-based differences in autonomic responses in the setting of CHF may be related to the female survival advantage. (J Cardiovasc Electrophysiol, Vol. 11, pp. 1071-1077, October 2000) [source] Heart rate variability , a therapeutic target?JOURNAL OF CLINICAL PHARMACY & THERAPEUTICS, Issue 2 2002H. C. Routledge Reduced heart rate variability (HRV) is a powerful and independent predictor of an adverse prognosis in patients with heart disease and in the general population. The HRV is largely determined by vagally mediated beat to beat variability, conventionally known as respiratory sinus arrhythmia. Thus, HRV is primarily an indicator of cardiac vagal control. It is still unclear whether the relationship between measures of cardiac vagal control and mortality is causative or mere association. Possible mechanisms by which cardiac vagal activity might beneficially influence prognosis include a decrease in myocardial oxygen demand, a reduction in sympathetic activity and a decreased susceptibility of the ventricular myocardium to lethal arrhythmia. In animals, augmentation of cardiac vagal control by nerve stimulation or by drugs is associated with a reduction in sudden death in susceptible models. In humans a number of drugs which have been shown to reduce mortality and sudden death in large randomised trials can also be demonstrated to increase HRV. As a result of this evidence, it has been suggested that the effect of drugs or other therapeutic manoeuvres on HRV might be used to predict clinical efficacy. The use of HRV as a therapeutic target is discussed in this review. [source] Raising and lowering of heart rate variability: Some clinical findings of Thought Field TherapyJOURNAL OF CLINICAL PSYCHOLOGY, Issue 10 2001Roger J. Callahan This clinical report presents some of the findings in Thought Field Therapy (TFT) that show both raising and lowering of heart rate variability (HRV). TFT algorithms are effective, but the specificity of diagnosed treatment gives results that are superior to algorithms. Some TFT treatments take only seconds to yield improved results on HRV. Toxins can undo a cured problem and lower HRV. TFT can overturn the effect of some toxins. It is hypothesized that TFT works by inputting a specific code that addresses and effects the healing system. HRV may be a measure of general physical and mental health. © 2001 John Wiley & Sons, Inc. J Clin Psychol 57: 1175,1186, 2001. [source] Heart rate variability does not tap putative efficacy of Thought Field TherapyJOURNAL OF CLINICAL PSYCHOLOGY, Issue 10 2001John P. Kline Callahan (2001) has offered a series of case reports in an effort to validate the rationale and methods of Thought Field Therapy (TFT). These case reports employ subjective ratings, that is, the Subjective Units of Distress (SUD) rating scale as well as a gross measure of heart rate variability (HRV). My criticisms center around (a) inappropriately strong inferences given exclusive reliance on case reports, a potentially biased sample, and lack of appropriate controls; (b) misinterpretation of statistical artifact as systematic effect; (c) lack of systematic evaluation of HRV changes; and (d) erroneous interpretation of HRV. Callahan's article provides no evidence for the efficacy of TFT nor does it provide evidence for the credibility of TFT's rationale. © 2001 John Wiley & Sons, Inc. J Clin Psychol 57: 1187,1192, 2001. [source] Increased heart rate variability correlation between mother and child immediately pre-operationACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 5 2009Y.-C. P. ARAI Background: Maternal distress would correlate with the children's mental status, thereby influencing the activity of the autonomic nervous system (ANS) of the children and mothers. We hypothesized that pre-anesthetic maternal ANS activity, when approaching close to their children's operation time, would correlate with children's ANS activity, and that the values of heart rate variability (HRV) would correlate. Methods: We calculated maternal and children's HRVs and analyzed the relationship between the two. A total of 24 pairs of mother and child were analyzed. Maternal and children's HRVs were recorded from the night before the child's surgery to the arrival to the operation room. Results: The ratios of low-frequency components (LF) to high-frequency components (HF) (LF/HF ratio) of children's and maternal HRVs obtained during the immediate pre-operative period (06:00,08:00 hours) showed a significantly, positive correlation, but no correlation was found for the LF/HF ratios obtained during the pre-operative night. Conclusion: The LF/HF ratios of HRV immediately before surgery in children and mothers showed a significant positive correlation. [source] Prenatal Alcohol Exposure Alters Biobehavioral Reactivity to Pain in NewbornsALCOHOLISM, Issue 4 2010Tim F. Oberlander Objectives:, To examine biobehavioral responses to an acute pain event in a Cape Town, South Africa, cohort consisting of 28 Cape Colored (mixed ancestry) newborns (n = 14) heavily exposed to alcohol during pregnancy (exposed), and born to abstainers (n = 14) or light (,0.5 oz absolute alcohol/d) drinkers (controls). Methods:, Mothers were recruited during the third trimester of pregnancy. Newborn data were collected on postpartum day 3 in the maternity obstetrical unit where the infant had been delivered. Heavy prenatal alcohol exposure was defined as maternal consumption of at least 14 drinks/wk or at least 1 incident of binge drinking/mo. Acute stress-related biobehavioral markers [salivary cortisol, heart rate (HR), respiratory sinus arrhythmia (RSA), spectral measures of heart rate variability (HRV), and videotaped facial actions] were collected thrice during a heel lance blood collection (baseline, lance, and recovery). After a feeding and nap, newborns were administered an abbreviated Brazelton Neonatal Behavioral Assessment Scale. Results:, There were no between-group differences in maternal age, marital status, parity, gravidity, depression, anxiety, pregnancy smoking, maternal education, or infant gestational age at birth (all ps > 0.15). In both groups, HR increased with the heel lance and decreased during the postlance period. The alcohol-exposed group had lower mean HR than controls throughout, and showed no change in RSA over time. Cortisol levels showed no change over time in controls but decreased over time in exposed infants. Although facial action analyses revealed no group differences in response to the heel lance, behavioral responses assessed on the Brazelton Neonatal Scale showed less arousal in the exposed group. Conclusions:, Both cardiac autonomic and hypothalamic,pituitary,adrenal stress reactivity measures suggest a blunted response to an acute noxious event in alcohol-exposed newborns. This is supported by results on the Brazelton Neonatal Scale indicating reduced behavioral arousal in the exposed group. To our knowledge, these data provide the first biobehavioral examination of early pain reactivity in alcohol-exposed newborns and have important implications for understanding neuro-/biobehavioral effects of prenatal alcohol exposure in the newborn period. [source] QT Interval Dispersion and Cardiac Sympathovagal Balance Shift in Rats With Acute Ethanol WithdrawalALCOHOLISM, Issue 2 2010Seiko Shirafuji Background:, Dysregulation of autonomic nervous system function and impaired homogeneity of myocardial repolarization are 2 important mechanisms for the genesis of ventricular arrhythmias in nonalcoholic subjects. Our previous study suggested that acute ethanol withdrawal promoted the shift of cardiac sympathovagal balance toward sympathetic predominance and reduced the vagal tone, which were related to a higher incidence of ventricular arrhythmia and related death. However, the homogeneity of myocardial repolarization and its relation with the cardiac sympathovagal balance are unknown, especially in alcoholic subjects. The aim of the present study was to clarify these points. Methods:, Male Wistar rats were treated with a continuous ethanol liquid diet for 49 days, and then subjected to 1-day withdrawal and 1-day withdrawal with 7-day carvedilol (can block the sympathetic nervous system completely via ,1, ,2, and , adrenergic receptors) pretreatment. The cardiac sympathovagal balance and homogeneity of myocardial repolarization were evaluated based on the heart rate variability (HRV) and QT interval dispersion (QTd: dynamic changes in QT interval duration). Results:, The increase in QTd was observed only in rats at 1-day withdrawal, but not in nonalcoholic, continuous ethanol intake, and 1-day withdrawal with 7-day carvedilol pretreatment rats. At 1-day withdrawal, the low-frequency power/high-frequency power (LF/HF) ratio in HRV was elevated and correlated with the QTd. The increased QTd and elevated LF/HF ratio were normalized by the 7-day carvedilol pretreatment in rats at 1-day ethanol withdrawal. Conclusions:, In rats with an abrupt termination of the chronic continuous ethanol intake, the homogeneity of myocardial repolarization impaired and correlated with the cardiac sympathovagal balance. Carvedilol pretreatment is associated with a reduction in both the QTd and LF/HF ratio, raising the possibility that the cardiac sympathovagal balance shift may be responsible for the impaired homogeneity of myocardial repolarization, and that ,-blocker pretreatment may decrease the mortality risk during alcoholic withdrawal. [source] | ||||||||||||||||||||||||||||||||||