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High-frequency Power (high-frequency + power)
Selected AbstractsHeart 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] 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] Asymptomatic leukocyturia and the autonomic nervous system in womenGERIATRICS & GERONTOLOGY INTERNATIONAL, Issue 2 2009Yoshimasa Igari Background: The present study sought to investigate the relationship between asymptomatic leukocyturia (ASL) and autonomic nervous function by power spectral analysis of the R-R intervals in women. Methods: One hundred and forty-two female outpatients aged 23,91 years were studied. We regarded ASL to be present if two consecutive samples were found to have 10 or more leukocytes/high-power field at ×400 magnification in a centrifuged midstream urine sample. The R-R intervals of all subjects were measured by the wavelet transform analysis system. This system detected R-R variation data distributed in two bands: low-frequency power (LF) (0.04,0.15 Hz) and high-frequency power (HF) (0.15,0.40 Hz). The ratio of LF to HF (LF/HF) was also determined. Post-void residual urine volume was measured using an automated, compact 3-D ultrasound device. Results: The patients with ASL had diabetes mellitus more frequently than those without ASL. Residual urine volume was significantly higher in the former than in the latter, while the HF values in both a recumbent position and a standing position were significantly lower in the former than in the latter (P = 0.003, P = 0.001, respectively). However, there were no significant differences in LF or LF/HF values in either a recumbent or a standing position between the two groups. The HF values in both a recumbent position and in a standing position were independent indicators of ASL, even after adjustment for age, diabetes mellitus and residual urine volume. Conclusion: The present study reveals the relationship between ASL and impairment of the parasympathetic nervous system in women. [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] Effects of sevoflurane on QT parameters in children with congenital sensorineural hearing lossANAESTHESIA, Issue 1 2009H. S. Kim Summary Sevoflurane prolongs the QT interval (QTI). Patients with congenital sensorineural hearing loss (SNHL) often have a prolonged QTI. This study was to investigate the effects of sevoflurane on the QTI in SNHL and control children. Thirty patients with SNHL and 30 controls were studied. The corrected QT interval (QTc), interval from peak to end of T wave (Tp-e) and QT variability index (QTVI) were analysed. QTc and Tp-e were estimated by the average QTc and Tp-e measured beat-by-beat for 15 min. Heart rate power spectral analysis was performed. In both groups, QTc and QTVI increased during anaesthesia, but Tp-e did not change. There were no differences in QTc, QTVI, Tp-e, low- and high-frequency power between the two groups. In both groups, sevoflurane lengthened the QTc and QTVI intervals but not Tp-e. [source] Autonomic Nervous System Modulation before the Onset of Sustained Atrioventricular Nodal Reentry TachycardiaANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 1 2010Gerardo Nigro M.D., Ph.D. Introduction: Our study was designed to analyze dynamic changes in autonomic tone before the onset of typical sustained atrioventricular nodal reentry tachycardia (AVNRT) in a large group of patients without structural heart disease. Materials and Methods: Twenty-four-hour Holter tapes from 42 consecutive patients (27 men and 15 women; aged 30 ± 21 years) with several episodes of sustained typical AVNRT were analyzed. The diagnosis was validated by transesophageal electrophysiological study. The time-domain calculated parameters were SDNN, SDANN, rMSSD, pNN50; the frequency-domain parameters were low-frequency power (LF, 0.04,0.15 Hz), high-frequency power (HF, 0.15,0.40 Hz), very low-frequency power (VLF, 0.008 to 0.04 Hz) and LF/HF. The mean values in the hour before the onset of sustained AVNRT were compared with the mean values of 2 hours before and 1 hour after the onset of sustained AVNRT. Results: The mean SDNN, rMSSD, pNN50, HF were significantly decreased during the hour preceding the onset of AVNRT, when compared to the mean values observed during the time periods selected. Instead, the LF values and LF/HF were increased before the onset of sustained AVNRT. No significant change in the VLF and atrial ectopic beats were observed. Conclusion: This study suggests that sustained typical AVNRT episodes are preceded by increase in adrenergic drive. Ann Noninvasive Electrocardiol 2010;15(1):49,55 [source] Characteristics of Heart Rate Variability Can Predict Impending Septic Shock in Emergency Department Patients with SepsisACADEMIC EMERGENCY MEDICINE, Issue 5 2007Wei-Lung Chen MD ObjectivesTo determine whether heart rate variability (HRV) measures can be used to predict which septic patients in the emergency department (ED) will progress to septic shock. MethodsThe authors prospectively enrolled consecutive patients who met the 2001 International Sepsis Definitions Conference criteria of sepsis and visited the ED of a university teaching hospital over a six-month period. In addition to the septic workup, a continuous 10-minute electrocardiogram recording was performed at the same time. The HRV measures were calculated off-line and correlated with the outcome of the patients. ResultsEighty-one patients aged 30,84 years who met the inclusion criteria were enrolled. The patients were classified as those with no septic shock (n= 60) and those with septic shock (n= 21), according to their outcome within six hours. The baseline root mean square successive difference, high-frequency power, and normalized high-frequency power of the septic shock group were significantly higher than those of the no septic shock group. The low-frequency power, normalized low-frequency power, and low-/high-frequency power ratio of the septic shock group were significantly lower than those of the no septic shock group. Multiple logistic regression analysis identified root mean square successive difference as the best predictor of impending septic shock for septic ED patients. ConclusionsHRV measures may be used to identify septic ED patients with impending septic shock. Among those HRV measures, root mean square successive difference seems to be the best indicator to predict the occurrence of septic shock. [source] Decrease in heart rate variability with overtraining: assessment by the Poincaré plot analysisCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 1 2004Laurent Mourot Summary Numerous symptoms have been associated with the overtraining syndrome (OT), including changes in autonomic function. Heart rate variability (HRV) provides non-invasive data about the autonomic regulation of heart rate in real-life conditions. The aims of the study were to: (i) characterize the HRV profile of seven athletes (OA) diagnosed as suffering of OT, compared with eight healthy sedentary (C) and eight trained (T) subjects during supine rest and 60° upright, and (ii) compare the traditional time- and frequency-domain analysis assessment of HRV with the non-linear Poincaré plot analysis. In the latter each R-R interval is plotted as a function of the previous one, and the standard deviations of the instantaneous (SD1) and long-term R-R interval variability are calculated. Total power was higher in T than in C and OA both in supine (1158 ± 1137, 6092 ± 3554 and 2970 ± 2947 ms2 for C, T and OA, respectively) and in upright (640 ± 499, 1814 ± 806 and 1092 ± 712 ms2 for C, T and OA, respectively; P<0·05) positions. In supine position, indicators of parasympathetic activity to the sinus node were higher in T compared with C and OA (high-frequency power: 419·1 ± 381·2, 1105·3 ± 781·4 and 463·7 ± 715·8 ms2 for C, T and OA, respectively; P<0·05; SD1: 29·5 ± 18·5, 75·2 ± 17·2 and 37·6 ± 27·5 for C, T and OA, respectively; P<0·05). OA had a marked predominance of sympathetic activity regardless of the position (LF/HF were 0·47 ± 0·35, 0·47 ± 0·50 and 3·96 ± 5·71 in supine position for C, T and OA, respectively, and 2·09 ± 2·17, 7·22 ± 6·82 and 12·04 ± 10·36 in upright position for C, T and OA, respectively). The changes in HRV indexes induced by the upright posture were greater in T than in OA. The shape of the Poincaré plots allowed the distinction between the three groups, with wide and narrow shapes in T and OA, respectively, compared with C. As Poincaré plot parameters are easy to compute and associated with the ,width' of the scatter gram, they corroborate the traditional time- and frequency-domain analysis. We suggest that they could be used to indicate fatigue and/or prevent OT. [source] Effects of age on the cardiac and vascular limbs of the arterial baroreflexEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 1 2003C. M. Brown Abstract Background Healthy ageing has several effects on the autonomic control of the circulation. Several studies have shown that baroreflex-mediated vagal control of the heart deteriorates with age, but so far there is little information regarding the effect of ageing on sympathetically mediated baroreflex responses. The aim of this study was to assess the effects of ageing on baroreflex control of the heart and blood vessels. Materials and Methods In 40 healthy volunteers, aged 20,87 years, we applied oscillatory neck suction at 0·1 Hz to assess the sympathetic modulation of the heart and blood vessels and at 0·2 Hz to assess the effect of parasympathetic stimulation on the heart. Breathing was maintained at 0·25 Hz. Blood pressure, electrocardiographic RR intervals and respiration were recorded continuously. Spectral analysis was used to evaluate the magnitude of the low-frequency (0·03,0·14 Hz) and high-frequency (0·15,0·50 Hz) oscillations in the RR interval and blood pressure. Responses to neck suction were assessed as the change in power of the RR interval and blood pressure fluctuations at the stimulation frequency from baseline values. Results Resting low- and high-frequency powers of the RR interval decreased significantly with age (P < 0·01). However, the low-frequency power of systolic blood pressure did not correlate with age. Spontaneous baroreflex sensitivity (alpha-index) showed a significant inverse correlation with age (r = ,0·46, P < 0·05). Responses of the RR interval and systolic blood pressure to 0·1 Hz neck suction stimulation were not related to age, however, the RR interval response to 0·2 Hz neck suction declined significantly with age (r = ,0·61, P < 0·01). Conclusions These results confirm an age-related decrease in cardiovagal baroreflex responses. However, sympathetically mediated baroreflex control of the blood vessels is preserved with age. [source] | ||||||||||