Significant Changes In Heart Rate Variability Research Articles

Novel heart rate variability index for wrist-worn wearable devices subject to motion artifacts that complicate measurement of the continuous pulse interval

Objective: Wearable health monitoring devices have recently become popular, but they can still only measure the average heart rate. Heart rate variability (HRV) is known to represent changes in the autonomic nervous system and analysis of HRV has the potential to be used for monitoring various wellness-related parameters such as sleep or stress. HRV analysis requires accurate measurement of the heartbeat interval. In wearable devices, it is difficult to accurately measure the heartbeat interval due to motion noise. In this paper we propose a new method for performing HRV analysis on photoplethysmographic (PPG) signals corrupted by motion artifacts measured at the wrist. Approach: A frequency-tracking algorithm based on the oscillator-based adaptive notch filter was used to measure instantaneous heart rate. The algorithm consists of a time-varying bandpass filter for enhancing the heartbeat signal and an adaptive mechanism for tracking heart rate frequency. By optimizing the filter bandwidth and forgetting factor of the adaptive mechanism, the frequency-tracking algorithm better reflects the variability of instantaneous heart rate. The new HRV index was calculated as the standard deviation of the heartbeat interval data converted using the heart rate estimated by the frequency-tracking algorithm. In order to verify the effectiveness of the proposed index, the new HRV index calculated for each sleep stage was compared with SDNN, the standard deviation of the heartbeat interval, which was calculated using simultaneous electrocardiogram measurements. In addition, changes in SDNN and the new index were compared during a socially evaluated speech task. Finally, the relationship between the new index and SDNN was compared with the data collected during daily activities over a 24 h period. Main results: Experimental results showed that statistically significant changes in HRV could be monitored in different sleep stages using the proposed method. In addition, when subjects were stressed by a socially evaluated speech task, significant reduction in HRV was observed using the proposed method. Finally, HRV values measured during daily activities over a 24 h period showed a high correlation coefficient of 0.812 with reference HRVs. Significance: The new HRV index calculated by the proposed method is expected to be an effective new solution for noisy PPG signals.

An investigation on the influence of yogic methods on heart rate variability.

The role of underlying mechanisms of yogic strategies which exert beneficiary effects on cardiac autonomic control is poorly understood. We have performed heart rate variability (HRV) analysis on subjects performing yogic methods and control subjects who mimic them through paced breathing and focused attention tasks using external cues. Heart rate (HR) time series is generated from electrocardiogram measured from subjects of yogic group (YG); performing yogic practices (n=15), paced breathing group (PBG); involved in breathing exercises cued at breathing rates (BR) from 3 to 15 cycles per minute (cpm) (n=23), normal breathing group (NBG) under regular breathing (n=15), and subjects performing three different cognitive tasks designated as focused attention group (FAG), (n=24). HRV is analyzed using coherence plots, spectrograms, HRV parameters, and instantaneous frequency recurrence plots (IFRP). HRV is similar among YG and PBG (at BR <12cpm) and significantly different for YG vs. NBG (p<0.001) and PBG vs. NBG (p<0.001). Regularity of breathing oscillations observed in HR is quantified using IFRP and is identical among FAG, PBG, and YG and significantly different for YG vs. NBG (p<0.01), PBG vs. NBG (p<0.01), and FAG vs. NBG (p<0.05). Low-frequency breathing (BR <12cpm) plays a primary role in eliciting physiologically significant changes in HRV. By identifying a similarity in breathing oscillations of HR of FAG, YG, and PBG, the results recognize the coexistence of attention and breathing strategies and postulate their joint role in sustaining autonomic benefits, while effects induced by breathing alone on HRV could be attained even intermittently.

The Effects of Subconcussive Impacts on Heart Rate Variability In Female Youth Soccer Players

BackgroundANS function can be measured noninvasively and relatively inexpensively through heart rate variability (HRV). Reduced HRV is representative of an uncoupling between the ANS and cardiovascular system, which may be proportional to the severity of a neurological injury. Reduced HRV has been observed in patients diagnosed with a sport‐related concussion, and therefore may be a useful outcome measure in identifying the chronic effects of heading during a youth soccer season.ObjectivesThe purpose of this study was to evaluate the effects of one season of competitive soccer, with the inherent subconcussive header impacts, on autonomic function in female youth soccer players.ParticipantsTwenty‐three female youth soccer players (13.4 ± 0.84 years old) were recruited from three competitive soccer teams.MethodsThe number of headers performed during the season were quantified using game video analysis. Players that performed fewer than the average number of headers (20) at the end of the season were classified into the “low header” group (N=13), while players with 20 or more headers at the end of the season were classified into the “high header” group (N=10). A five‐minute resting electrocardiogram data was collected from all players at baseline and post‐season. These data were analyzed using a two‐way mixed ANOVA in order to calculate heart rate variability time‐domain and frequency‐domain measures, which included mean heart rate, standard deviation of the N‐N interval, total power, low frequency, high frequency, and low to high frequency ratio (LF/HF).ResultsThere was a statistically significant interaction between time and group for LF/HF from preseason (6.24 ± 5.77; 2.96 ± 1.81) to postseason (6.79 ± 6.75; 1.90 ± 1.02) in the low and high header groups, respectively (p=.024, partial h2=0.313). There were no other statistically significant changes in HRV for any other time or frequency domain outcome measure.ConclusionOur preliminary findings indicate that the LF/HF in the high header group differed from the low header group over the course of a soccer season. This may indicate that an increased number of chronic head impacts might result in an imbalance between sympathetic and parasympathetic activity, which would signify an alteration in autonomic function. These preliminary results demonstrate that additional research is needed in order to further understand the effects of heading on ANS function.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

A Neurovisceral Approach to Autism: Targeting Self-Regulation and Core Symptoms Using Neurofeedback and Biofeedback

Mu Rhythm Synchrony Neurofeedback (MRS-NFB) has shown promise in improving electrophysiological and behavioral deficits in autism spectrum disorder (ASD). Heart rate variability biofeedback (HRV-BFB), a method for improving self-regulation of the autonomic nervous system (ANS), has yet to be tested as a clinical intervention for ASD. This study evaluated the impact of HRV-BFB on symptoms of ASD; and whether a combined HRV-BFB + MRS-NFB intervention would be more efficacious than HRV-BFB alone. Fifteen children with a verified diagnosis of ASD completed the study. Participants were assigned to either an HRV-BFB group (Group 1) or a combined HRV-BFB + MRS-NFB group (Group 2). All children underwent pre- and postassessments of electroencephalography (EEG), heart rate variability (HRV), and parent-reported behaviors. No significant between-groups differences were observed on any parent-reported behaviors. Group 1 showed significant pre–post improvements in emotion regulation and social behavior, while Group 2 showed significant pre–post improvements in emotional lability and autistic behaviors. Group 2 also showed significant improvements in RMSSD and lnHF (vagal tone) indices of HRV over time, while Group 1 displayed no significant changes in HRV over time. Group 1 showed an increase in mu suppression posttraining, and Group 2 showed a reduction in mu suppression posttraining. The results suggest that HRV-BFB, alone or in combination with MRS-NFB, may improve behavioral features of autism. A combined approach may be more efficacious in enhancing HRV, while the implications of each approach on mu suppression are mixed. Neurovisceral approaches that teach self-regulation offer a novel treatment avenue for ASD.

Association between Age and Changes in Heart Rate Variability after Hemodialysis in Patients with Diabetes.

Background: Heart rate variability (HRV) represents changes in the time between successive heart beats, and it has been used to assess the autonomic nervous system. Previous studies have reported autonomic dysfunction in diabetic patients undergoing hemodialysis (HD), however, no studies have evaluated the effects of age on changes in HRV in these patients. The aim of this study was to examine the effects of age on changes in HRV in diabetic HD patients.Methods: We enrolled 84 diabetic patients receiving maintenance HD. HRV was measured before and after HD to assess changes in HRV (ΔHRV). The patients were divided into two groups based on their age (65 years< or ≥65 years).Results: Compared to the patients aged <65 years, those aged ≥65 years had a higher high frequency (HF) % (p = 0.032) before HD. The patients aged <65 years had a significant increase in very low frequency, low frequency (LF), and HF after HD. The patients aged ≥65 years had a significant increase in LF, but a significant decrease in HF% after HD. There was a significant interaction between age and change of HF% (p = 0.023) after HD. After multivariate adjustments for clinical, biochemical data and medications, systolic blood pressure, total cholesterol, hemoglobin, and hemoglobin were associated with ΔLF, whereas cerebrovascular disease, systolic blood pressure, and fasting glucose were associated with ΔHF% in patients aged ≥65 years.Conclusion: Our study demonstrated significant changes in HRV after HD in diabetic patients. In the patients aged ≥65 years, LF was increased, whereas HF% was decreased significantly after HD. Among the HRV parameters, age had an interaction with the change of HF%.

Effects of HRV-Guided vs. Predetermined Block Training on Performance, HRV and Serum Hormones.

The aim of this study was to compare heart rate variability -guided (HRVG) and predetermined (PD) block periodization of high intensity aerobic training (HIT). Endurance performance, neuromuscular performance, heart rate variability (HRV) and serum hormone concentrations were measured before, in the middle and after the 8-week training period in 24 endurance trained males. Both groups improved significantly maximal treadmill velocity (Vmax) (p<0.001) and 3000 m running performance (HRVG; p<0.001 and PD; p=0.001). The relative changes in Vmax and countermovement jump were significantly greater in HRVG (p<0.05). Nocturnal heart rate decreased in both groups (p<0.01), but HRV (RMSSD, LF and TP) increased significantly only in HRVG (p<0.05). The significant increase in serum testosterone concentration was observed from mid to post in HRVG (p<0.05). Significant correlations were found between individual Vmax changes and absolute serum testosterone levels. Individual baseline level of HF correlated significantly with Vmax changes in PD. Block periodization of HIT seems to be an effective way to improve endurance and running performance in already endurance trained males. Based on training induced increases in endurance and neuromuscular performance combined with significant changes in HRV and serum testosterone levels observed in HRVG, individually HRV -guided block training may be more optimal compared to predetermined training.

Changes In Heart Rate Variability And Training Load In Elite Football Players

Heart rate variability (HRV) is a popular and accessible monitoring tool utilized ubiquitously in the field to measure autonomic nervous system activity, readiness to train, and training adaptations. Acquisition of this information is essential for coaches, practitioners and athletes in order to effectively monitor positive training adaptations, nonfunctional over-reaching, injury and illness risk. However, longitudinal data assessing HRV changes with respect to training load in elite football is lacking. PURPOSE: To investigate changes in HRV and training load across several weekly training blocks in elite football. METHODS: Six male professional footballers (three defenders, three midfielders) from an English Premier League squad agreed to participate in this study. HRV was assessed with the ithlete application (HRV Fit Ltd, UK) using an Apple iPad2 (Apple Inc, CA), and a Polar T31 heart rate monitor (Polar Electro Ltd, Finland). HRV was calculated for each participant prior to the daily training session. Physical training load was monitored using a Global Positioning System (GPS) to quantify total distance (TD), high speed distance (HSD), training load (TL), impacts, maximum speed (MS), accelerations and decelerations, and energy expenditure (EE). Training sessions were separated into five equal training blocks (weeks 1 - 3, weeks 4 - 6, weeks 7 - 9, weeks 10 - 12 and weeks 13 - 15). RESULTS: There was a significant decrease in TD, HSD, TL, impacts and EE and a significant increase in MS, accelerations and decelerations across the five training blocks (p ≤ 0.03). However, there was no significant change in HRV (p = 0.27). CONCLUSION: The significant change in TL across the 15 week training period, despite no change in HRV may be due to the heterogeneity that exists in elite football players, where some athletes show smaller reductions in HRV in response to training compared to others. Subsequently it is important that individual changes in HRV are interpreted alongside additional monitoring methods (e.g. wellness, training load) to ensure that quantification of training adaptation, readiness to train and overreaching is accurate.

Effects of High-Dose α-Lipoic Acid on Heart Rate Variability of Type 2 Diabetes Mellitus Patients with Cardiac Autonomic Neuropathy in Korea.

BackgroundDiabetic cardiac autonomic neuropathy (CAN) is one of the important complications of diabetes. It is characterized by reduced heart rate variability (HRV).MethodsIn this randomized, double-blind, placebo-controlled, multicenter trial, 75 patients were randomly assigned to one of two groups. One group (n=41) received α-lipoic acid (ALA) at an oral dose of 600 mg/day for the first 12 weeks and then 1,200 mg/day for the next 12 weeks. The other group (n=34) received placebo treatment for 24 weeks. CAN was assessed by measuring HRVs in people with diabetes.ResultsMost of the baseline measures for HRVs were similar between the ALA and placebo groups. Although there were no statistically significant HRV changes in the ALA group compared to the placebo group after 24 weeks of trial, we found a positive tendency in some of the HRV parameters of the ALA group. The standard deviations of normal-to-normal RR intervals in the standing position increased by 1.87 ms in the ALA group but decreased by −3.97 ms in the placebo group (P=0.06). The power spectrum of the low frequency (LF) band in the standing position increased by 15.77 ms2 in the ALA group, whereas it declined by −15.04 ms2 in the placebo group (P=0.08). The high frequency/LF ratio in the upright position increased by 0.35 in the ALA group, whereas it declined by −0.42 in the placebo group (P=0.06). There were no differences between the two groups regarding rates of adverse events.ConclusionAlthough a slight improvement tendency was seen in HRV in the ALA group, there were no statistically significant HRV changes in the ALA group compared to the placebo group after 24 weeks of trial. However, the high oral dose of ALA was well-tolerated.

Expression of heat-shock protein 72 mRNA in relation to heart rate variability of Sahiwal and Karan-Fries in different temperature-humidity indices.

Aim:To investigate the effect of temperature-humidity index (THI) on the expression pattern of heat-shock protein 72 (HSP72) mRNA of Sahiwal and Karan-Fries (KF) cattle in different THIs.Materials and Methods:Five different periods of a year were selected based on combinations of Tmax/Tmin, viz., P1: <20°C/<10°C; P2: >20°C/<10°C, P3: <30°C/<15°C; P4: >35°C/<20°C, and P5: >35°C/>20°C. The THI was calculated from the records of temperature and relative humidity in different periods. Heart rate variability (HRV) was calculated from electrocardiogram records in different periods. HSP72 mRNA expression was estimated by reverse transcription polymerase chain reaction.Results:The THI recorded during P1, P2, P3, P4, and P5 were 55.5, 60.3, 70.1, 74.5, and 79.0, respectively. THI in P4 and P5 were stressful to animals. HSP72 mRNA expression increased during cold stress in P1 in Sahiwal and heat stress in P4 and P5 in both Sahiwal and KF. Sahiwal maintained increased HSP72 mRNA expression longer than KF without causing a significant change in HRV.Conclusion:Both low THI in winter and high THI in summer increased HSP72 mRNA of Sahiwal and KF without significant change in HRV. Thermotolerance of Sahiwal could be due to the maintenance of higher HSP72 expression longer than KF in prolonged heat stress in summer.

Comparison of Autonomic Reactions during Urodynamic Examination in Patients with Spinal Cord Injuries and Able-Bodied Subjects.

Background/PurposeThis study compares heart rate variability (HRV) and systolic blood pressure (SBP) changes of spinal cord injury (SCI) patients during urodynamic study (UDS) with able-bodied controls.MethodsTwenty four complete suprasacral SCI patients (12 tetraplegia and 12 paraplegia) and 12 age-matched able-bodied volunteers received BP and HRV evaluation throughout urodynamic examination. We chose seven time points during the examinations: resting, Foley catheter insertion, start of infusion, and infused volume reaching 1/4, 2/4, 3/4 and 4/4 of maximal capacity. At each time point, electrocardiogram with a duration of 5 min was used for power spectral density analysis of HRV.ResultsOnly control subjects displayed significant elevation of SBP during Foley catheter insertion compared to resting values. Both control and tetraplegic groups experienced significant elevation of SBP at maximal bladder capacity compared to resting values. Tetraplegic values were also significantly greater than the other two groups. Control subjects displayed significant elevation of low frequency/high frequency (LF/HF) ratios during Foley catheter insertion and when approaching maximum bladder capacity. These findings were not seen in the paraplegic and tetraplegic groups. However, subgroup analysis of tetraplegic subjects with SBP elevation >50 mmHg demonstrated a similar LF/HF response to the able-bodied controls.ConclusionTetraplegic patients experienced BP elevation but did not experience significant changes in HRV during bladder distension. This finding may imply that different neurological pathways contribute to AD reaction and HRV changes during bladder distension. However, profound AD during UDS in tetraplegic patients was associated with corresponding changes in HRV. Whether HRV monitoring would be beneficial in SCI patients presenting with significant AD, it needs further studies to elucidate.

Effect of a weight reduction program on baseline and stress-induced heart rate variability in children with obesity.

Autonomic dysregulation is a well-established feature in adults with obesity but not in children. Since this dysregulation could contribute to weight dynamics, this study aimed to compare autonomic regulation in children with obesity and normal-weight peers and to track autonomic status during weight reduction. Sixty children with obesity and 27 age- and sex-matched normal-weight healthy participants were included. Heart rate variability (HRV) was assessed at baseline and during a mental stress test and a subsequent recovery period. Children with obesity were investigated both upon admission and discharge. Upon admission, no significant differences in HRV parameters were found for normal-weight participants and those with obesity. Inpatient treatment led to significant changes in HRV with increase in general variability (standard deviation of the normal-to-normal interval (SDNN), P < 0.001) as well as of parasympathetic regulation (root mean square successive difference (RMSSD) and high frequency power (logHF), P < 0.01). Children with obesity had sympathetic activation similar to normal-weight controls during mental stress with subsequent return to baseline values, and weight loss did not affect this profile. A weight reduction program induced a change in autonomic activity in children with obesity toward parasympathetic dominance but had no influence on autonomic nervous system reactivity during stress conditions.

Change in Heart Rate Variability After the Adult Attachment Interview in Dissociative Patients

The aim of this study was to assess heart rate variability (HRV) in individuals with dissociative disorders (DD) before and after the Adult Attachment Interview (AAI). Electrocardiograms were recorded before, during, and after the AAI in 13 individuals with DD and 13 healthy participants matched for age and gender. Significant change in HRV was observed only in the DD group. After the AAI, those with DD showed significant increases in the low frequency/high frequency ratio (pre-AAI = 1.91 ± 1.19; post-AAI = 4.03 ± 2.40; Wilcoxon test = –2.76, p = .005). Our results suggest that the retrieval of childhood attachment experiences in individuals with DD is associated with a change in HRV patterns that could reflect the emotion dysregulation of dissociative psychopathological processes.

Heart rate and blood pressure variability in patients with myasthenia gravis

This cross-sectional case control study included subjects aged between 18 and 65 years with diagnosis of myasthenia gravis (MG) in Osserman's Stage I and Stage IIa and those in remission with positive and negative acetylcholine receptor antibody (AChRAb). They were evaluated for heart rate variability (HRV) and other conventional autonomic functions. Patients with co-morbidities that can affect autonomic nervous system were excluded. Repetitive nerve stimulation test (RNST), nerve conduction test, AChRAb assay, and computerized tomography (CT) of chest were done in all the patients. All patients of MG who fulfilled the inclusion criteria had a minimum drug-free period of 6 h which was followed by HRV and other conventional tests. Thirty subjects fulfilling study criteria and an equal number of age and gender-matched healthy subjects were enrolled as controls. Autonomic function tests revealed significant changes in HRV (both time and frequency domain) parameters suggestive of parasympathetic deficiency as well as shifting of sympathovagal balance towards raised sympathetic tone. With regards to conventional autonomic function tests, there was statistically significant decrease in values of heart rate-based tests as well as blood pressure-based test (isometric handgrip test) in study group compared with controls, again indicative of significant parasympathetic deficiency and minimal sympathetic deficiency. We conclude that in MG, cholinergic transmission is affected more diffusely than previously thought.

The effect of celiac plexus block on heart rate variability

Celiac plexus block (CPB) can be used for treating intra-abdominal visceral pain syndromes. The celiac plexus is the largest plexus of the sympathetic nervous system. Several nerve blocks have a marked effect on autonomic nervous activity. Furthermore, stellate ganglion block changes cardiac autonomic nervous activity. Thus, CPB could influence the sympathetic activity of the cardiac plexus. The aim of the present study was to see whether CPB modulated heart rate variability (HRV) in patients with pancreatic cancer. Twelve patients received neurolytic CPB using 14 ml absolute alcohol. Data recorded in a palm-sized electrocardiographic unit were analyzed for HRV. CPB using a neurolytic solution did not induce any significant changes in the low-frequency (LF)/high-frequency (HF) ratio of HRV (LF/HF, P = 0.4642). Furthermore, the procedure did not induce any significant changes in blood pressure (systolic, P = 0.5051; diastolic, P = 0.5180). CPB did not induce any significant changes in HRV or hemodynamics.

How to Predict the Impact of Methylphenidate on Cardiovascular Risk in Children with Attention Deficit Disorder: Methylphenidate Improves Autonomic Dysfunction in Children with ADHD

Background. Although stimulants have long been touted as treatments for attention deficit disorder with or without hyperactivity (ADHD), in recent years, increasing concerns have been raised about the cardiovascular safety of these medications. We aimed to prove if measurements of autonomic function with time domain analysis of heart rate variability (HRV) in 24-hour Holter ECG are useful to predict the risk of sudden cardiac death in ADHD children and adolescents. Methods. We analysed HRV obtained from children with the diagnosis of ADHD prior to (N = 12) or during medical therapy (N = 19) with methylphenidate (MPH), aged 10.8 ± 2.0 years (mean ± SD), who were referred to our outpatient Paediatric Cardiology Clinic to rule out heart defect. As a control group, we compared the HRV data of 19 age-matched healthy children without heart defect. Results. Average HRV parameters from 24-hour ECG in the ADHD children prior to MPH showed significant lower values compared to healthy children with respect to rMSSD (26 ± 4 ms versus 44 ± 10 ms, P ≤ 0.0001) and pNN50 (6.5 ± 2.7% versus 21.5 ± 9.0%, P ≤ 0.0001). These values improved in MPH-treated children with ADHD (RMSSD: 36 ± 8 ms; pNN50: 14.2 ± 6.9%). Conclusion. Children who suffer from ADHD show significant changes in HRV that predominantly reflects diminished vagal tone, a well-known risk factor of sudden cardiac death in adults. In our pilot study, MPH treatment improved HRV.

Heart rate variability in prediction of individual adaptation to endurance training in recreational endurance runners

The aim of this study was to investigate whether nocturnal heart rate variability (HRV) can be used to predict changes in endurance performance during 28 weeks of endurance training. The training was divided into 14 weeks of basic training (BTP) and 14 weeks of intensive training periods (ITP). Endurance performance characteristics, nocturnal HRV, and serum hormone concentrations were measured before and after both training periods in 28 recreational endurance runners. During the study peak treadmill running speed (Vpeak ) improved by 7.5 ± 4.5%. No changes were observed in HRV indices after BTP, but after ITP, these indices increased significantly (HFP: 1.9%, P=0.026; TP: 1.7%, P=0.007). Significant correlations were observed between the change of Vpeak and HRV indices (TP: r=0.75, P<0.001; HFP: r=0.71, P<0.001; LFP: r=0.69, P=0.01) at baseline during ITP. In order to lead to significant changes in HRV among recreational endurance runners, it seems that moderate- and high-intensity training are needed. This study showed that recreational endurance runners with a high HRV at baseline improved their endurance running performance after ITP more than runners with low baseline HRV.

540 PREDICTIVE VALUE OF INFLAMMATORY MARKERS ON CARDIOVASCULAR EVENTS IN PATIENTS WITH CHRONIC HEART FAILURE

In patients with previous myocardial infarction (MI), depressed heart rate variability (HRV) may reflect a reduction in vagal activity and lead to cardiac electrical instability. Interventions designed to increase HRV may be of clinical interest. Data on the effects of calcium antagonists on HRV in post-MI patients are very limited. The aim of our study was to assess the effects of verapamil on HRV and on the sympathovagal balance after MI. Fifty consecutive patients with a first MI, stable sinus rhythm, and left ventricular ejection fraction >0.40 were studied. Each patient underwent two 24-hour Holter recordings, 1 at baseline and another after 4 days of treatment with verapamil retard (180 mg 2 times daily). Time and frequency domain parameters of HRV were analyzed. All time domain measurements increased significantly after verapamil: the standard deviation of all NN intervals (SDNN) from 87.1 ± 31.4 to 98.1 ± 30.3 ms (p <0.05) and the log-transformed percentage of pairs of adjacent NN intervals that differ >50 ms (pNN50) from 0.57 ± 0.42 to 0.76 ± 0.45 (p <0.01). The standard deviation of the averages of RR interevals (SDANN) (75.9 ± 30.1 vs 86.3 ± 29.4 ms, p <0.05), root-mean-square of successive differences between RR intervals (rMSSD) (23.0 ± 11.7 and 28.1 ± 13.1 ms, p <0.01), and the triangular HRV index (28.3 ± 9.6 vs 23.4 ± 8.6, p <0.001) also increased. A significant inverse correlation was found between improvement in HRV indexes induced by verapamil and baseline values. Spectral analysis showed a significant increase in high-frequency power of 58.5% without changes in low and very low components. With normalized units, significant reductions in low-frequency power and low- to high-frequency ratio were observed. Diabetic patients did not show any significant changes in HRV on administration of verapamil. These findings indicate that verapamil, administered during the subacute phase of MI, improves both global and short-period indexes of HRV and induces a shift in the sympathetic-parasympathetic interaction toward vagal predominance. This effect may contribute to an explanation of the beneficial effects of verapamil that have been reported in post-MI patients.

EFFICACY AND SAFETY OF BISOPROLOL IN YOUNG MEN WITH ARTERIAL HYPERTENSION AND OBESITY

Aim. To evaluate effect of bisoprolol on circadian blood pressure (BP) profile, autonomic cardiovascular regulation, lipid and carbohydrate metabolism in young patients with arterial hypertension (HT) and obesity. Materials and methods. 36 men aged 18 to 35 years with HT 1-2 degrees, obesity 1-2 degrees and signs of sympathetic over activity were examined. In addition to standard clinical examination assessment of heart rate variability (HRV) during orthostatic test with spectral analysis, ambulatory BP monitoring, evaluation of lipid profile, oral glucose tolerance test, determination of immunoreactive insulin, insulin resistance index and functional activity of beta-cells were performed. Anthropometric measurements included body mass index and waist circumference. Bisoprolol in the initial dose of 5 mg QD orally for 12 weeks was assigned to all patients. After 12 weeks of bisoprolol treatment repeated examination was performed. Results. Significant changes in HRV after 12 weeks of treatment with bisoprolol was found. Parasympathetic influence of autonomic nervous system increased during orthostatic test. Contribution of the slow and very slow waves, which reflect sympathetic and neurohumoral activity , reduced. Total spectral power was significantly increased. Initial tachycardia reduced. Target BP values were achieved after 12 weeks of treatment with bisoprolol 5 mg QD. Increase in a number of dippers and decrease in a number of nondippers in terms of both systolic and diastolic BP was observed. Heart rate and HRV was significantly decreased. No adverse events in terms of lipid or carbohydrate metabolism were found during treatment with bisoprolol. Conclusion. Bisoprolol 12 week treatment resulted in sympathetic activity decrease and parasympathetic activity increase, achievement of BP target levels, improvement of BP circadian profile. Bisoprolol therapy in dose of 5 mg/day demonstrated metabolic neutrality in patients with risk factors of cardiovascular diseases and type 2 diabetes.

The Role of the Selective Serotonin Re-Uptake Inhibitor Sertraline in Nondepressive Patients with Chronic Ischemic Heart Failure: A Preliminary Study

Selective serotonin re-uptake inhibitors (SSRIs) have been associated with better psychiatric status, functional capacity, and fewer arrhythmias in depressive patients with heart failure (HF). In this study, we tested the impact of sertraline (an SSRI) on patients with HF, but not clinical depression. We studied 62 clinically stable, nondepressive patients with ischemic HF (New York Heart Association class: I-II), and implantable cardioverter-defibrillator (ICD). Following psychiatric evaluation and quality of life (QoL) assessment, 24-hour electrocardiogram recordings including heart rate variability (HRV) and ICD interrogation were performed every 4 months for 1 year. Ventricular effective refractory period (ERP) at 600-, 500-, and 400-ms cycle length and the inducibility of ventricular tachycardia (VT) were assessed via the ICD. After that, sertraline 50 mg/day was administered for 12 months and the whole evaluation was repeated. Sertraline was associated with fewer ventricular extrasystoles per 24 hours and a significant change in HRV (increase in mean R-R, 5-minute standard deviation of RR intervals, and root mean-square difference of successive RR intervals, and reduction in ultra and very low frequency). It was also followed by an improvement in patients' QoL. A trend toward a decrease was observed in the number of recalled nonsustained VTs. The episodes of sustained VT were not significantly reduced. Ventricular ERPs and VT inducibility remained unaltered. In clinically stable, nondepressive patients with ischemic HF and ICD, sertraline is associated with reduced ventricular extrasystoles, better QoL, and a possible improvement in some HRV indexes. This suggests that SSRIs may have a favorable clinical impact on these patients, independent of the improvement in depressive symptoms.

Anxiety as a factor influencing physiological effects of acupuncture

This study investigated the influence of manual acupuncture on heart rate variability and the role which anxiety can play in modifying physiological outcomes. Analysis of heart rate variability (HRV) was used as a sensitive and a reliable indicator of the balance between sympathetic and parasympathetic regulation of the heartbeat. Two groups of healthy female subjects were recruited into the study. The control group (n=30) attended one experimental session where no acupuncture treatment was used. The experimental group (n=30) attended three sessions in which unilateral manual stimulation of acupuncture points LU7 and KD6 was performed. The stimulation of the acupuncture points LU7 and KD6 was not associated with significant changes in HRV. Previous familiarity with acupuncture did not influence the outcomes but level of anxiety had a strong impact on physiological outcomes. Stimulation of LU7 acupuncture point counterbalanced naturally occurring sympathetic increase over time and had relaxing and harmonizing effect on the heart rhythm without influencing subjective perception of increased anxiety. Stimulation of KD6 acupuncture point had sympathetic influence on HRV in subjects with low "trait" anxiety and this influence was nullified by simultaneous stimulation of LU7 acupuncture point. It seems likely that the level of anxiety can modify HRV during acupuncture treatment and up to 40 min after the treatment. Psychological factors such as anxiety level should be considered as having important influence on physiological response to acupuncture.