Cardiac Autonomic Nervous System Research Articles

Response and Adaptation of the Cardiac Autonomic System to Functional High-intensity Interval Training with Respiratory Facemasks: Impacts of the Training Period and Facemask Modality During a COVID-19 Pandemic

Background: Following the SARS-CoV-2 pandemic in 2019, medical face masks were widely recommended for large numbers of people and for long periods of time. The effect of wearing surgical and N95 face masks during long-term high-intensity interval training on the cardiac autonomic system has not been reported. Methods: Eighteen healthy men were randomly divided into three groups (surgical mask, N95 mask, and no mask) and performed high-intensity interval training with (80 - 90%-heart rate max) intensity three times a week, three repetitions in a session for four weeks. Heart rate variability parameters were evaluated with an electrocardiogram device and Kubius software. The R-R interval was recorded for 5 minutes in a sitting position in the pre-and post-modified Bruce test before and after four weeks of interval training to extract parasympathetic (RMSSD, HF, SD1), sympathetic indices (LF, LF/HF) and RR mean. We used the two-way ANOVA test and the Bonferroni post hoc test. Results: In all groups, four-week functional HIIT exercises increased the resting parasympathetic indices (RMSSD, SD1) compared to baseline levels. This increase was more evident in the N95 mask group than in the surgical mask group. In addition, the five-minute recovery of the cardiac autonomic system after a modified Bruce test following functional HIIT exercise increased parasympathetic tone (RMSSD, HFn.u) in all groups compared to baseline levels. Therefore, a four-week adaptation to HIIT exercises leads to faster recovery of sympathetic indices (LFn.u, LF/HF) in the no mask group, as compared to the surgical and N95 groups. Despite the above, there was no significant difference in the recovery and resting values of cardiac autonomic system indices between the two types of surgical masks and N95 compared to the control group (no mask). Conclusions: Four weeks of high-intensity interval training using surgical and N95 face masks improved the cardiac autonomic nervous system. This data is important for recommending the use of face masks during physical activity.

Early detection of the impact of combined taxane and carboplatin treatment on autonomic nerves in patients with cervical cancer: Measurement of heart rate variability.

Background: Previous studies have shown that heart rate variability (HRV) analysis is a sensitive indicator of chemotherapy-induced cardiotoxicity. However, most studies to date have observed long-term effects using long-term analyses. The main purpose of this study was to evaluate the acute effect of chemotherapy on the cardiac autonomic nervous system (ANS) in patients with cervical cancer (CC) by examining short-term HRV. Methods: Fifty patients with CC admitted to the Department of Gynecology and Oncology of the First Affiliated Hospital of Bengbu Medical College were enrolled in the study. Based on their chemotherapy regimens, the patients were divided into a DC group (docetaxel + carboplatin) and a TC group (paclitaxel + carboplatin). A 5-min resting electrocardiogram (ECG) was collected before and the day after chemotherapy: the time domain (standard deviation of normal-to-normal intervals (SDNN) and root mean square of successive differences (RMSSD)) and frequency domain (low-frequency power (LF), high-frequency power (HF), and (LF/HF)) parameters were analyzed, and the differences before and after chemotherapy were compared. Results: The results showed that SDNN, RMSSD and HF were significantly higher in the DC and TC groups after chemotherapy than before (p < 0.05, Cohen's d > 0.5). In addition, LF was significantly higher after TC than before chemotherapy (p < 0.05, Cohen's d > 0.3), and LF/HF was significantly lower after DC than before chemotherapy (p < 0.05, Cohen's d > 0.5). Conclusion: Chemotherapy combining taxane and carboplatin can increase the HRV of CC patients in the short term, and HRV may be a sensitive tool for the early detection of chemotherapy-induced cardiac ANS perturbations.

Intrinsic Cardiac Neuromodulation in the Management of Atrial Fibrillation- A Potential Missing Link?

Atrial fibrillation (AF) is the most common supraventricular arrhythmia that is linked with higher cardiovascular morbidity and mortality. Recent evidence has demonstrated that catheter-based pulmonary vein isolation (PVI) is not only a viable alternative but may be superior to antiarrhythmic drug therapy for long-term freedom from symptomatic AF episodes, a reduction in the arrhythmia burden, and healthcare resource utilization with a similar risk of adverse events. The intrinsic cardiac autonomic nervous system (ANS) has a significant influence on the structural and electrical milieu, and imbalances in the ANS may contribute to the arrhythmogenesis of AF in some individuals. There is now increasing scientific and clinical interest in various aspects of neuromodulation of intrinsic cardiac ANS, including mapping techniques, ablation methods, and patient selection. In the present review, we aimed to summarize and critically appraise the currently available evidence for the neuromodulation of intrinsic cardiac ANS in AF.

Beneficial Performance Effects of Training Load Intensification Can Be Abolished by Functional Overreaching: Lessons From a Water Polo Study in Female Athletes.

Brisola, GMP, Dutra, YM, Murias, JM, and Zagatto, AM. Beneficial performance effects of training load intensification can be abolished by functional overreaching: Lessons from a water polo study in female athletes. J Strength Cond Res 37(6): e391-e402, 2023-The purpose of this study was to compare the outcomes from 2 weeks of training load intensification strategy in female water polo players diagnosed with functional overreaching (F-OR) with no F-OR players (acute fatigue) on the performance outcomes and hormonal, immunological, and cardiac autonomic nervous system responses. Twenty-two female water polo players were allocated into control and intensification group during 7 weeks. The swimming performance, biochemical parameters, heart rate variability, profile of mood states, and upper respiratory tract infection symptoms were assessed twice before and twice after 2 weeks of intensification period. F-OR showed a worsening in total time of the repeated sprint ability (RSA) test compared with the control group and the acute fatigue group after intensification ( p ≤ 0.035). Furthermore, after the tapering period, the F-OR group maintained worse total time of the RSA test than the acute fatigue group ( p = 0.029). In addition, the acute fatigue group showed improvement in total time of the RSA test after intensification compared with the control group ( p < 0.001). No significant interactions were found for the other parameters. Therefore, periods of intensification without the F-OR development can promote higher gains in the total time of the RSA test after intensification and tapering period.

Effects on heart rate from direct current block of the stimulated rat vagus nerve

Objective. Although electrical vagus nerve stimulation has been shown to augment parasympathetic control of the heart, the effects of electrical conduction block have been less rigorously characterized. Previous experiments have demonstrated that direct current (DC) nerve block can be applied safely and effectively in the autonomic system, but additional information about the system dynamics need to be characterized to successfully deploy DC nerve block to clinical practice. Approach. The dynamics of the heart rate (HR) from DC nerve block of the vagus nerve were measured by stimulating the vagus nerve to lower the HR, and then applying DC block to restore normal rate. DC block achieved rapid, complete block, as well as partial block at lower amplitudes. Main Results. Complete block was also achieved using lower amplitudes, but with a slower induction time. The time for DC to induce complete block was significantly predicted by the amplitude; specifically, the amplitude expressed as a percentage of the current required for a rapid, 60 s induction time. Recovery times after the cessation of DC block could occur both instantly, and after a significant delay. Both blocking duration and injected charge were significant in predicting the delay in recovery to normal conduction. Significance. While these data show that broad features such as induction and recovery can be described well by the DC parameters, more precise features of the HR, such as the exact path of the induction and recoveries, are still undefined. These findings show promise for control of the cardiac autonomic nervous system, with potential to expand to the sympathetic inputs as well.

Sex differences in estimates of cardiac autonomic function using heart rate variability: effects of dietary capsaicin.

Heart rate variability (HRV) estimates the autonomic nervous system (ANS) influence on the heart and appears sex-specific. Sensory afferents exhibit sex-specificity; although, it is unknown if Capsaicin, an agonist for transient receptor potential vanilloid channel-1 (TRPV1), alters cardiac ANS activity in a sex-dependent manner, which could be important given the predictive nature of HRV on risk of developing hypertension. Thus, we explored if there was sex-specificity in the effect of capsaicin on estimated cardiac ANS activity. HRV was measured in 38 young males (M: n = 25) and females (F: n = 13), in a blinded-crossover design, after acute ingestion of placebo or capsaicin. Resting HR, RR-interval, root-mean-square of successive differences (RMSSD), natural log-transformed RMSSD (LnRMSSD), standard deviation of n-n intervals (SDNN), number of pairs of successive n-n intervals differing by > 50ms (NN50), and percent NN50 (PNN50) were obtained using standard techniques. Significant sex differences were observed in mean HR (M: 59 ± 9.3 vs. F: 65 ± 12 beats/min, p = 0.036, η2 = 0.098), minimum HR (M: 47 ± 8.3 vs. F: 56 ± 12 beats/min, p = 0.014, η2 = 0.124), and NN50 (M: 177 ± 143 vs. F: 29 ± 17, p < 0.001, η2 = 0.249). There was a significant interaction of sex*treatment (p = 0.02, η2 = 0.027) for RMSSD, where males increased (78 ± 55 vs. 91 ± 64ms), and females decreased (105 ± 83 vs. 76 ± 43ms), placebo vs. capsaicin. This controlled study recapitulates sex differences in HR and HRV, but revealed a sexual dimorphism in the parasympathetic response to capsaicin, perhaps due to differing TRPV1-afferent sensitivity, highlighting a potential mechanism for differential regulation of hemodynamics, and CVD risk, and should beconsidered in future studies.

Development of neuromodulation for atrial fibrillation: a narrative review.

Atrial fibrillation (AF) is a prevalent clinical arrhythmia with a high incidence of disability and mortality. Autonomic nervous system (ANS) plays a crucial role in the onset and persistence of AF, and can lead to electrophysiological changes and alterations in atrial structure. Both animal models and clinical findings suggest that parasympathetic and sympathetic activity within the cardiac ANS could induce atrial remodeling and AF. Remodeling of the cardiac autonomic nerves is a significant structural basis for promoting AF. Given the challenges faced by conventional pharmacological and atrial ablation techniques in the treatment of AF, increasing attention has been paid to autonomic intervention strategies for AF. Current research has demonstrated that the frequency and severity of AF episodes can be significantly reduced by modulating the activity of ANS. ANS neuromodulation is expected to lead more effective and personalized treatment options for patients with AF. The objective of this review is to provide a broader perspective for future related studies by reviewing preclinical and clinical studies of neuromodulation methods for the treatment of AF, searching for relevant approaches to treat AF, as well as identifying the strengths and weaknesses demonstrated by current relevant studies, and providing researchers with a broader overview of the latest neurological treatments for AF. A narrative review was conducted on the literature on PubMed, WanFang data, and Google Scholar, including all relevant studies published until November 2023. In this review, we delve into the innervation of cardiac autonomic nerves, the role of the ANS in the development and maintenance of AF, and the current neuromodulation methods for AF treatment. These methods include stellate ganglion (SG) resection or ablation, vagus nerve stimulation (VNS), thoracic subcutaneous nerve stimulation (ScNS), renal denervation (RDN) therapy, ganglionated plexus (GP) ablation, and epicardial botulinum toxin or CaCl2 injection. More and more research suggests that neuromodulation methods for the treatment of AF have broad prospects. ANS plays a crucial role in AF development and maintenance through cardiac autonomic nerve remodeling. Modulating ANS activity can significantly reduce AF frequency and severity, offering more personalized treatment options. Current research on autonomic interventions for AF shows promise for more effective and personalized treatments.

Effects of an 18-Week Integrated Yoga Program on Cardiac Autonomic Function in Breast Cancer Patients Undergoing Adjuvant Chemotherapy: A Randomized Controlled Trial.

Cardiotoxicity is a commonly observed adverse effect seen in breast cancer (BC) patients undergoing chemotherapy with attributes toward cardiac autonomic dysfunction (CAD). Yoga, a mind-body system of medicine that has been shown to improve cardiac autonomic nervous system (ANS) activity in various health conditions, could be an effective adjuvant approach in addressing CAD. This study aims to investigate the protective effects of Integrated Yoga Therapy (IYT) on ANS functioning, assessed using Heart rate variability (HRV) in breast cancer patients undergoing chemotherapy. A total of 68 (stage I-III) BC patients were randomly assigned into 2 groups: Treatment as Usual group (TAU) and TAU with Yoga Therapy group (TAUYT). All patients underwent anthracycline-based adjuvant chemotherapy for a total of 6 cycles with 21 days/cycle. During chemotherapy, the TAUYT group received IYT 5 days a week for 18 weeks, compared with usual care alone in the TAU group. Resting heart rate (RHR) and HRV, measured in both the time and frequency domains, were used to assess the cardiac ANS function of each patient before and after 6 cycles of chemotherapy. A total of 30 subjects in the TAU group and 29 subjects in the TAUYT group were included in the analysis. At baseline (before chemotherapy), there were no significant differences between the TAU and TAUYT groups in terms of RHR and HRV indices. However, after chemotherapy, patients in the TAU group had a significantly higher average RHR (P < .02) and lower HRV indices with reduced parasympathetic indices: RMSSD (P < .01), pNN50% (P < .04), high-frequency power (P < .001) and increased sympathetic indices: low-frequency power (P < .001) with sympathovagal imbalance: LF/HF (P < .001) compared with patients in the TAUYT group. The study showed the protective effects of yoga therapy on CAD in patients receiving anthracycline-based chemotherapy for BC, proposing yoga as a potential adjuvant intervention in improving cardiac health and preventing cardiovascular-related morbidities. This trial is registered with the Clinical Trials Registry-India (CTRI) database (CTRI/2020/10/028446; October 16, 2020).

Physiological Effects of Using Citrus Mint Flavored Mouthwash

This study aimed to investigate the effect of flavored mouthwash on peripheral and cardiac autonomic nervous system activity. In a within-subject experimental design, 10 male and 10 female healthy adults went through two types of mouthwashes, one was with citrus mint flavor and another was with spice mint flavor, right after performing a 20-minute calculation task given as a cognitive stressor. Along with subjective evaluation, skin conductance and electrocardiogram was recorded throughout the experiment. Although there was no difference in the subjective stress levels between the two conditions, the level of skin conductance decreased more remarkably and significantly during the recovery period when the participants used citrus mint mouthwash. The findings suggest that a particular flavored mouthwash may provide physiological effect on user regardless of its subjective sensation and the citrus mint type mouthwash might be better suited for use in need of a relaxation.

Ultrasound-mediated piezoelectric nanoparticle modulation of intrinsic cardiac autonomic nervous system for rate control in atrial fibrillation.

Rate control is a cornerstone of atrial fibrillation treatment. Barium titanate nanoparticles (BTNPs) are piezoelectric nanomaterials that can generate local electromagnetic fields under ultrasound activation, stimulating nearby neuronal tissue. This study aimed to modulate the inferior right ganglionated plexus (IRGP) of the heart and reduce the ventricular rate during rapid atrial pacing (RAP)-induced atrial fibrillation using ultrasound-mediated BTNPs. Adult male beagles were randomly divided into a phosphate-buffered saline (PBS) group (n = 6) and a BTNP group (n = 6). PBS or nanoparticles were injected into the IRGP of both groups before RAP. The biological safety of the material was evaluated according to electrophysiology recordings, thermal effects and level of inflammation. Compared to the PBS group, the BaTiO3 piezoelectric nanoparticle group had reduced ventricular rates in the sinus rhythm and atrial fibrillation models after stimulating the IRGP by applying ultrasound. In addition, transient stimulation by BTNPs did not lead to sustained neuronal excitation in the IRGP. The activation of the BTNPs did not induce inflammation or thermal damage effects in the IRGP. Ultrasound-mediated BTNP neuromodulation can significantly reduce the ventricular rate by stimulating the IRGP. Thus, ultrasound-mediated BTNP neuromodulation is a potential therapy for atrial fibrillation rate control.

Effects of Riceberry Rice Bran Oil Supplementation on Oxidative Stress and Cardiovascular Risk Biomarkers in Older Adults with Prehypertension.

We investigated the changes in the oxidative stress and cardiovascular disease risk biomarkers, including the activity of the cardiac autonomic nervous system, in older adults with prehypertension following Riceberry rice bran oil supplementation. A total of 35 women aged 60 to 76 years with prehypertension were randomly allocated to two groups, one of which was supplemented with rice bran oil (n=18) and the other with Riceberry rice bran oil (n=17) at 1,000 mg daily for 8 weeks. Prior to and after the supplementation, oxidative stress and cardiovascular risk biomarkers (primary outcomes), heart rate variability, and blood pressure (secondary outcomes) were investigated. Results showed that plasma malondialdehyde, blood glutathione disulfide, and tumor necrosis factor-alpha levels were significantly decreased, and the ratio of reduced glutathione to glutathione disulfide significantly increased in both groups after supplementation (all P<0.05). No significant differences were observed between groups. Heart rate variability and blood pressure did not statistically significantly change subsequent to supplementation in either group and did not differ between groups. In conclusion, Riceberry rice bran oil supplementation for 8 weeks alleviates oxidative stress and inflammation in older adults with prehypertension to a similar extent as rice bran oil supplementation.

791 CAN ALARMINS BECOME A THERAPEUTIC TARGET FOR A PATIENTS WITH ATRIAL FIBRILLATION?

Abstract The link between alarmins and atrial fibrillation is clear and well known in the literature. We performed a non-systematic review about role of alarmins in pathophysiological mechanism of AF, hypothesizing their role in potential novel therapeutic targets for arrhythmia. Several studies have shown a key role of HMGB1 in AF physiopathology. We have seen an almost direct correlation between HMGB1 and oxidative stress in the inflammatory process of AF. Wu et al. observed that HMGB1 is higher in patients with permanent AF, because they experienced a continuous inflammatory tissue damaging impulse. It was shown a prothrombotic and procoagulative role of HMGB1, increased in patients with AF and atrial thrombosis. Scherschel et al. showed higher concentration of S100β protein in AF patients undergoing catheter ablation. Neuronal injury by intrinsic cardiac autonomic nervous system (ICSN) upon catheter treatment released damage-associated molecular pattern proteins (DAMPs) as S100β protein. In vitro studies dealing with murine intracardiac neuros showed that S100β decreased potential action and increased neuronal cells growth. Many studies demonstrate HSP70 protective role when intracellular, at high concentrations in patients who do not develop arrhythmia after cardiac injury, such as bypass, and low concentrations preoperatively in patients who later develop arrhythmia. At the serum level, on the other hand, it becomes an important marker of cellular damage and oxidative stress, also related to increased IL-2 AND IL-4. Conclusions These results could be considered for new therapeutic strategies, as inhibition of oxidative stress, novel therapeutic targets of anticoagulant drugs and considering alarmins as predictive or prognostic biomarkers of disease.

The role of autonomic denervation in the success of atrial fibrillation ablation: Can pulsed-field ablation provide the answer?

Although the role of cardiac autonomic nervous system (CANS) in triggering and maintenance of atrial fibrillation (AF) is established, the potential value of adjuvant autonomic denervation in AF ablation is debated. Autonomic denervation from collateral thermal injury of CANS during radiofrequency/cryo-based pulmonary vein (PV) isolation (PVI) is thought to confer additional clinical benefit.1 In contrast, follow-up studies with 24-hour Holter-based heart rate variability (HRV) assessment demonstrated recovery of HRV parameters to the preprocedure level within 3–6 months.

Autonomic imbalance and atrial ectopic activity-a pathophysiological and clinical view.

The heart is one of the most richly innervated organs and the impact of the complex cardiac autonomic network on atrial electrophysiology and arrhythmogenesis, including on atrial ectopy, is widely recognized. The aim of this review is to discuss the main mechanisms involved in atrial ectopic activity. An overview of the anatomic and physiological aspects of the cardiac autonomic nervous system is provided as well as a discussion of the main pathophysiological pathways linking autonomic imbalance and atrial ectopic activity. The most relevant data on cardiac neuromodulation strategies are emphasized. Unanswered questions and hotspots for future research are also identified.

Autonomic nervous system and arrhythmias in structural heart disease.

The autonomic nervous system functions in a fine-tuned manner to dynamically modulate cardiac function during normal physiological state. Autonomic dysregulation in cardiac disease states such as myocardial infarction and heart failure alters this fine balance, which in turn promotes disease progression and arrhythmogenesis. Neuromodulatory interventions that aim to restore this balance at distinct levels of the cardiac neuraxis thus have been shown to be effective in the treatment of arrhythmias. This review first describes the anatomy of the cardiac autonomic nervous system and the pathological changes that occur with neural remodeling in the setting of scar and cardiomyopathy, followed by therapeutic interventions for neuraxial modulation of arrhythmias such as atrial fibrillation and ventricular tachyarrhythmias.

Chronic intermittent hypoxia worsens brain damage and sensorimotor behavioral abnormalities after ischemic stroke: Effect on autonomic nervous activity and sleep patterns

ObjectiveSleep apnea (SA) is characterized by intermittent hypoxia (IH), which increases sympathetic activity and sleep fragmentation, thus increasing the risk of stroke. SA is a highly prevalent disease and can worsen prognosis in patients with stroke. However, the correlation of changes in the cardiac autonomic nervous system and sleep patterns under IH with sensorimotor behavior and cerebral infarction after stroke remains unclear. We hypothesized that dysregulated autonomic activity and unstable sleep patterns induced by IH and correlated with cerebral infarction and abnormal sensorimotor behavior after middle cerebral artery occlusion (MCAO). MethodsWistar–Kyoto rats (WKY) were divided into IH (hypoxia: 5 % O2, 8 h/day) and RA group (room air) for 2 weeks and both groups were subjected to MCAO. After MCAO, the IH group was continuously exposed to IH for 1 week. The 24-h physiological signals, blood pressure, and sensorimotor behavior were recorded at baseline (Bas), the first and second weeks during IH (RA/IH1W and RA/IH2W, respectively), and poststroke. ResultsBefore MCAO, IH caused sympathetic activity during sleep and parasympathetic activity of active waking (AW) to increase. Moreover, IH reduced the accumulated time and duration of paradoxical sleep (PS) and increased the interruption during sleep. After MCAO, IH increased blood pressure, more severe brain damage, and poor sensorimotor performance. Moreover, IH reduced autonomic activity after MCAO and decreased sympathetic activity was associated with poor sensorimotor performance. ConclusionAutonomic activity and sleep patterns affected by IH were correlated with increased cerebral infarction and poor sensorimotor behavior after MCAO.

Abstract 13303: Influence of ARNI on Cardiac Autonomic Nervous System

Background Mortality in heart failure with reduced ejection fraction (HFrEF) is associated with imbalance of cardiac autonomic nervous system (CANS). Sacubitril/ Valsartan (ARNI) reduces risk of death and HFrEF hospitalization. Whether ARNI exerts effects on CANS has not been studied. Accordingly, we prospectively compared heart rate variability (HRV) as a noninvasive measure of CANS before and after initiation of ARNI therapy. Methods: The study was as a single-arm prospective interventional study. Patients with HFrEF underwent echocardiography and standardized 30-minute 12-lead Holter ECG recording before and 3 months after initiation of ARNI therapy. Study endpoints were changes in HRV parameters (standard deviation of normal-to-normal intervals (SDNN), mean square of differences between consecutive R-R intervals (RMSSD), periodic repolarization dynamics (PRD) and deceleration capacity (DC) as well as left ventricular ejection fraction (LVEF) and heart rate (HR). Results: Between June 2021 and March 2022 we recruited 63 consecutive patients. At follow-up 48 (76.2%) patients were still on ARNI and therefore analyzed. Mean age was 65±13 years, 88% were male. All patients received identical beta-blockers dosage at baseline and follow-up. Heart rate was reduced by ~12% (P=0.005). SDNN increased by ~42% (P&lt;0.001), RMSSD by ~55% (P&lt;0.001) and ~DC by 370% (P&lt;0.001). No change in PRD was observed (P=0.13). These results were accompanied by increased LVEF (28±6% vs. 38±10%, P&lt;0.001) and reduced plasma nt-proBNP levels (5083±790 pg/ml vs. 1838±621 pg/ml, P=0.002). NYHA class improved from III to II. Conclusion Significant increase of parasympathetic CANS tone was observed after initiation of ARNI therapy as evidenced by decreased HR, increased DC, SDNN and RMSSD. Part of the beneficial effects of ARNI might be related to the accentuation of parasympathetic CANS modulating mortality risk and risk for HFrEF hospitalizations.

Does transcatheter ventricular septal defect closure affect heart rate variability in children?

BackgroundHeart rate variability (HRV) is a sign of the cardiac autonomic nervous system. Its evaluation in pediatric ventricular septal defect (VSD) cases before and after transcatheter closure contributes to an understanding of cardiac autonomic control. MethodsNineteen children with VSDs treated with transcatheter closure and 18 healthy children were enrolled in this study. A 24-h Holter rhythm monitor was applied to all patients before VSD closure and to those in the control group. Holter rhythm monitoring was repeated at three months in the patient group. HRV parameters were measured using the Cardio Scan Premier 12® program. Frequency-domain (total power; very-low-frequency, low-frequency (LF), and high-frequency (HF) indices; and the LF/HF ratio) and time-domain (standard deviation of all RR intervals (SDNN), standard deviation of 5-min averages of RR intervals (SDANN), the SDNN index, percentage of the difference between adjacent RR intervals, and the square root of the mean of the sum of square differences between adjacent filtered RR intervals) parameters were assessed. ResultsBefore the procedure, SDNN, SDANN, and total power values were lower in the patient group than in the control group; other parameters were similar in the two groups. No significant difference in the SDNN, SDANN, or total power was detected between the patient and control groups in the third month, indicating that autonomic control of patients’ hearts became normal during the third postoperative month. No correlation was detected between any hemodynamic parameters and any time-domain or frequency-domain parameters before closure. ConclusionThis study showed that transcatheter closure of VSDs changed HRV parameters in pediatric patients.

Alterations in heart rate variability before and after percutaneous coronary intervention in patients with ischaemic heart disease

Objectives: Heart rate variability (HRV) is the beat-to-beat variation of heart rate and an important non-invasive tool to study the cardiac autonomic nervous system activity. Ischaemic heart disease (IHD) patients are often considered to have a state of sympathetic predominance. Elimination of myocardial ischaemia with percutaneous coronary intervention (PCI) could restore autonomic balance. Hence, this study aimed to evaluate HRV measures, after successful revascularisation among IHD patients. Materials and Methods: A total of 145 male IHD patients planned for coronary angiography were recruited. Fifteen minutes of electrocardiogram recording was done. Short-term HRV analyses of all the patients were acquired and time-domain indices (standard deviation of normal-to-normal intervals [SDNN], root-mean-squared differences of successive R-R intervals [rMSSD]) and frequency-domain indices (low-frequency [LF] power, high-frequency [HF] power and total power [TP]) were analysed. Before and after PCI, all measurements were made. Results: This study included 145 male IHD patients with the mean age of 54.57 ± 10.81 years. There was a significant decrease in SDNN, rMSSD, LF, HF and TP whereas increase in LF/HF ratio following revascularisation. These changes in measures of neurocardiac regulation correlated with risk factors and medication on regression analysis. Conclusion: Increase in LF/HF ratio with the decrease in SDNN, rMSSD, LF, HF and TP in patients with IHD who underwent coronary intervention infers changed cardiac autonomic balance with this surgical procedure. These measures could be potentially used as prognostic measures in the future studies.

ARNI effects in HFrEF. Risk reduction beyond LVEF

Abstract Background The imbalance of cardiac autonomic nervous system function plays an important role in heart failure associated mortality. ARNI has demonstrated a paramount effect in reducing risk of death and hospitalization for worsening of heart failure. However, its exact mechanism of action remains only partly understood. We sought to prospectively compare heart rate variability as a noninvasive measure of cardiac autonomic nervous system function. Methods The study design was prospective sequential observational. Patients served as their own internal control. Patients with heart failure with reduced ejection fraction (HFrEF) receiving optimal medical therapy who were scheduled for a switch to ARNI therapy underwent echocardiography and a standardized 30-minute 12-lead Holter ECG recording before starting ARNI therapy. A monitoring of the parameters was performed 3 months after the start of therapy. Physicians were instructed to increase ARNI dose to the highest tolerated or maximum dose. Besides left ventricular ejection fraction (LVEF) we assessed heart rate (HR), standard deviation of normal-to-normal intervals (SDNN) and mean square of differences between consecutive R-R intervals (RMSSD). Results We recruited 55 patients and baseline characteristics were as follows: age 65±12 years, male sex 78%, NT-proBNP 4989±809 pg/ml, LVEF 28±6%, HR 75±9 bpm, SDNN 43±2 ms, RMSSD 19±2 ms. All patients received beta-blocker therapy and the dosage was similar at baseline and follow-up. After 3 months of ARNI therapy, heart rate showed a significant reduction of 7% (74±14 bpm vs. 69±11 min, P=0.005). SDNN increased by 49% (43±2 ms vs. 64±4 ms, P&amp;lt;0.001) and RMSSD by 42% (19±2 ms vs. 27±3 ms, P=0.01). These results were accompanied by increased LVEF (28±6% vs. 38±10%, P&amp;lt;0.001) and reduced plasma NT-proBNP levels (4989±809 pg/ml vs. 2602±87 pg/ml, P&amp;lt;0.04). NYHA Class of affected patients changed from III to II. Conclusion After changing from ACE/AT1-I to ARNI, significant improvement of autonomic cardiac nervous system function could be observed. ARNI apparently activates the parasympathetic nervous system as suggested by decreased HR and increased SDNN and RMSSD. Therefore, part of its cardioprotective and beneficial effects may relate to the restoration of autonomic cardiac nervous system function. Potential beneficial effects regarding incidence of sudden cardiac arrest may relate to these observations. Funding Acknowledgement Type of funding sources: None.