Clinical Autonomic Research最新文献

Purpose: The present review investigates the responses of heart rate variability indices following high-intensity interval aerobic exercise, comparing it with moderate-intensity continuous exercise in adults, with the aim of informing clinical practice.

Methods: Searches were conducted in four databases until March 2023. Eligible studies included randomized controlled trials that assessed heart rate variability indices such as the standard deviation of normal-to-normal heartbeat intervals (SDNN), the root mean square of successive differences (RMSSD), the proportion of the number of pairs of successive normal-to-normal (NN or R-R) intervals that differ by more than 50 ms (NN50) divided by the total number of NN intervals (pNN50), power in high frequency range (HF), power in low frequency range (LF), and LF/HF before and after high-intensity interval and moderate-intensity continuous aerobic exercise. The risk of bias in included studies was evaluated using the RoB 2 tool.

Results: A total of 16 studies were included in the systematic review, while 9 were included in the meta-analysis. Overall, the majority of included individuals were healthy and young. Our meta-analysis indicated that individuals who performed high-intensity interval exercise showed a slower recovery to baseline levels for HF (standardized mean difference, SMD -0.98 [95% CI -1.52 to -0.44], p < 0.001) and LF (SMD -0.42 [95% CI -0.81 to -0.02], p = 0.04) within the first 10 min of recovery, which did not occur after 1 h. Among the 16 included studies, 10 had some concerns related to bias risk, while 6 were classified as high risk.

Conclusions: High-intensity interval aerobic exercise results in delayed recovery of HF and LF indices within the first 10 min after the session. However, our review indicates that healthy individuals restore modulation of the autonomic nervous system to baseline levels after this time interval, regardless of exercise intensity.

Purpose: Recent studies have reported blunted increases in blood pressure (BP) during static handgrip (SHG) in patients with heart failure with preserved ejection fraction (HFpEF), which may be attributed to abnormal sympathetic reactivity during exercise and/or impaired muscle metaboreflex function. However, it is unknown whether the sympathetic neural response to SHG and isolated muscle metaboreflex activation via post-exercise circulatory occlusion (PECO) are attenuated in HFpEF.

Methods: Thirty-nine patients with HFpEF and 24 age-matched non-HFpEF controls were studied in the supine position. BP, heart rate (HR), and muscle sympathetic nerve activity (MSNA) were measured during SHG at 40% of maximal voluntary contraction until fatigue followed by 2-min PECO.

Results: Resting mean arterial pressure (MAP) was lower and peak increase (Δ) in MAP was smaller in patients with HFpEF than in controls during SHG (Δ23 ± 15 [standard deviation] vs. Δ34 ± 15 mmHg; P = 0.007) and PECO (Δ15 ± 11 vs. Δ19 ± 9 mmHg; P = 0.047). HR was greater in patients at rest but did not differ between the two groups at peak SHG. Patients had higher resting MSNA burst frequency than controls (37 ± 14 vs. 27 ± 13 bursts/min; P = 0.031); however, burst incidence was not different between the groups (P = 0.226). There were no differences in MSNA responses to SHG (Δ19 ± 15 vs. Δ18 ± 10 bursts/min at peak; P = 0.841) or PECO (Δ3 ± 12 vs. Δ5 ± 7 bursts/min; P = 0.495) between groups.

Conclusion: The patients with HFpEF maintained sympathetic reactivity but had an attenuated pressor response during fatiguing SHG. Additionally, muscle metaboreflex activation of vasomotor sympathetic outflow appeared to be minimal in both groups, with no significant difference between patients and controls.

Purpose: Autonomic dysfunction is a common and often debilitating feature of long-COVID (LC), however, studies evaluating frequency and severity of chronic autonomic dysfunction in LC are limited. We utilized an established online cohort of participants with LC to assess duration and severity of autonomic dysfunction, impact on quality of life, risk factors of autonomic diagnoses including postural tachycardia syndrome (POTS), and efficacy of common treatments.

Methods: Our international cohort included 526 adults with LC aged 20-65 years who previously completed baseline evaluations of LC symptoms, autonomic symptom burden, and quality of life. Participants repeated survey instruments and completed new instruments assessing risk factors and symptom mitigation strategies. A subset of individuals completed a 10-min active stand test. Multivariable logistic regression identified predictors of autonomic symptom burden and incident autonomic diagnoses including POTS.

Results: A total of 71.9% of participants with LC had a Composite Autonomic Symptom Score-31 (COMPASS-31) score ≥ 20, suggestive of moderate-to-severe autonomic dysfunction. The median symptom duration was 36 [30-40] months, and 37.5% of participants could no longer work or had to drop out of school due to their illness. In addition, 40.5% of individuals with autonomic dysfunction were newly diagnosed with POTS, representing 33% of the total LC cohort. Female sex and joint hypermobility were associated with an increased risk of autonomic dysfunction.

Conclusions: Evidence of chronic moderate-to-severe autonomic dysfunction was seen in most participants with LC in our cohort and was significantly associated with reduced quality of life and functional disability. POTS was the most common post-COVID autonomic diagnosis.

Purpose: Increased beat-to-beat heart rate variability (HRV) is a feature of patients with Parkinson's disease (PD) who carry the G2019S mutation in the LRRK2 gene (LRRK2-PD). Since LRRK2 mutations have incomplete penetrance, HRV changes preceding PD conversion would likely be observed only in a subset of LRRK2 non-manifesting carriers (NMC). We aimed to assess HRV in a subgroup of NMC with distinctive characteristics of LRRK2-PD, identified through clustering analysis.

Methods: HRV measures derived from 300 normal heartbeat intervals extracted from the electrocardiograms of 25 NMC, 32 related non-carriers (RNC), 27 unrelated healthy controls, and 14 patients with LRRK2-PD were analyzed. Clinical symptoms were evaluated using questionnaires and scales, and three NMC subgroups were identified using a k-means cluster analysis on the basis of the deceleration capacity of heart rate (DC) and Rényi entropy. Standard and advanced HRV measures were compared using multiple regression analysis, controlling for age, sex, and mean heart rate.

Results: Beat-to-beat HRV markers were significantly increased in a subgroup of seven NMC (NMC2, 28%) compared with RNC and controls. Increased irregularity and DC were also verified in the NMC2 compared with controls, and were typical traits in both the NMC2 and RNC. Overall, the HRV profile of NMC2 was comparable to that of patients with LRRK2-PD. NMC2 further exhibited greater motor and non-motor traits than the other NMC, RNC, and controls.

Conclusions: Our results confirmed that HRV characteristics of LRRK2-PD are also found in a subset of NMC displaying clinical traits of LRRK2-PD. Further research is needed to clarify whether higher HRV represents a LRRK2-PD prodromal manifestation.

Purpose: Cardiovascular autonomic neuropathy remains underdiagnosed in type 1 diabetes mellitus, posing a risk for severe complications, particularly in patients with lowered V̇O_2max, compared to controls. This study aimed to determine whether heart rate variability during cardiovascular autonomic reflex tests reveals early signs of cardiovascular autonomic neuropathy in patients with uncomplicated type 1 diabetes mellitus and normal cardiovascular fitness, compared to healthy controls.

Methods: A type 1 diabetes mellitus group (n = 14) with no other diagnosed diseases (diabetes duration 15 ± 7 years) and a control group (n = 31) underwent deep breathing test, passive orthostatic test, and cardiopulmonary exercise test. Participants were assessed for heart rate variability, heart rate, blood pressure, and V̇O_2max (mL/min/kg).

Results: Participant characteristics, including V̇O_2max (mL/min/kg), showed no significant differences. The type 1 diabetes mellitus group had higher systolic blood pressure during the supine phase of the orthostatic test than healthy controls (131.6 ± 14.7 mmHg vs. 122.4 ± 10.8 mmHg, p = 0.022). After 5 mins in the upright position, systolic blood pressure (132.2 ± 20.6 mmHg vs. 118.7 ± 11.7 mmHg, p = 0.036), heart rate (85 (76; 89) bpm vs. 75 (72; 83) bpm, p = 0.013), and the root mean square of successive RR interval differences (20.22 (11.22; 27.42) vs. 27.11 (19.90; 35.52), p = 0.033) were significantly different compared to controls.

Conclusion: Patients with uncomplicated type 1 diabetes mellitus, despite having normal cardiorespiratory fitness, exhibited higher systolic pressure and greater sympathetic activation in orthostatic tests, suggesting subclinically altered cardiovascular autonomic function.

Introduction: Water intake is known to be effective in preventing orthostatic hypotension (OH). However, it is unknown whether water intake would be effective in acutely preventing exercise-induced OH.

Methods: Fourteen adults (men/women: 7/7, age: 20 ± 8 years) were recruited. Each subject underwent two protocols with and without 500 ml water intake using a randomized crossover design (Water vs. Control). Participants underwent 30 min of cycle ergometry at the 60-70% predicted VO₂ max. OH and hemodynamics were assessed before and after exercise, and immediately (Water 1) and 20 min (Water 2) after the water intake. OH was evaluated with a 1-min standing test as the criteria for systolic blood pressure (SBP) < 90 mmHg. A cross-spectral analysis for RR and SBP variability was used to evaluate the cardiac autonomic activity and baroreflex sensitivity.

Results: In both protocols, the incidence of OH increased after the exercise. The incidence of OH was lower in Water than in Control at Water 1 (OR: 0.093, 95% CI: 0.015-0.591). Heart rate was lower and SBP was higher in Water than in Control at Water 1 and 2 (P < 0.05). High-frequency power of RR variability and transfer function gains in Water were normalized and higher than in Control at Water 1 and 2 (P < 0.05). The ratio of low- to high-frequency power of RR variability in Water was normalized and lower in Water than in Control at Water 1 (P < 0.05).

Conclusion: Our findings indicate that water intake may prevent acute exercise-induced OH, accompanied by normalized cardiac autonomic activity and baroreflex sensitivity.

Purpose: The semiautomated carbon monoxide (CO) rebreathing method has been introduced as a noninvasive and radiation-free blood volume estimation method. We tested whether the semiautomated CO rebreathing method can detect the blood volume deficit in postural orthostatic tachycardia syndrome (POTS). In addition, we explored the relationship between blood volume estimated from CO rebreathing and body impedance.

Patients and methods: We recruited 53 subjects (21 female patients with POTS, 19 healthy female participants, and 13 healthy male participants) to record blood volumes and hemodynamic data. Blood volumes were measured by CO rebreathing and segmental body impedance. Linear regression models to predict normal values of red blood cell volume (RBCV), plasma volume (PV), and total blood volume (BV) were developed. Percentage deviations from the predicted normal volumes were calculated.

Results: Patients with POTS had lower RBCV (25.18 ± 3.95 versus 28.57 ± 3.68 mL/kg, p = 0.008, patients with POTS versus healthy female participants), BV (64.53 ± 10.02 versus 76.78 ± 10.00 mL/kg, p < 0.001), and BV deviation (-13.92 ± 10.38% versus -0.02 ± 10.18%, p < 0.001). Patients with POTS had higher supine heart rate (HR) (84 ± 14 versus 69 ± 11 bpm, p < 0.001) and upright HR (123 ± 23 versus 89 ± 22 bpm, p < 0.001). We found a correlation between BV deviation and upright HR in patients with POTS (r = -0.608, p = 0.003), but not in healthy participants. Volumes from the CO rebreathing and body impedance were well correlated (r = 0.629, p < 0.001).

Conclusions: The CO rebreathing method can detect BV deficit, as well as the RBCV deficit in patients with POTS. The negative correlation between BV deviation and upright HR indicates that hypovolemia is one of the pathophysiological causes of POTS. Correlations between body impedance and CO rebreathing volume suggest its usefulness for measurements of volume changes.

Purpose: Long-coronavirus disease (long-COVID) is associated with initial orthostatic hypotension and postural orthostatic tachycardia syndrome. Whether altered autonomic tone underlies these abnormalities is unknown. We compared autonomic function between patients with long-COVID and healthy controls, and within patients with long-COVID with different orthostatic hemodynamic phenotypes.

Methods: Patients with long-COVID (n = 94; F = 76; 42 years [36, 53 years] with initial orthostatic hypotension: n = 40; F = 32; 49 years [39, 57 years]; postural orthostatic tachycardia syndrome: n = 29; F = 26; 39 years [33, 47 years]; or no abnormalities: n = 25; F = 18; 42 years [35, 49 years]), and healthy controls (n = 33; F = 25; 49 years [30, 62 years]) completed a 10-min active stand with beat-to-beat hemodynamics. Heart rate variability, blood pressure variability, and baroreflex sensitivity were calculated as indirect measures of cardiovascular autonomic health. Continuous data (median [95% confidence interval]) were analyzed with Mann-Whitney U tests or Kruskal-Wallis tests with Dunn's corrections.

Results: Patients with long-COVID had lower upright high frequency heart rate variability (p = 0.04) and low frequency blood pressure variability (p = 0.001) than controls. Patients with initial orthostatic hypotension had lower supine baroreflex sensitivity compared with patients without abnormalities (p = 0.01), and lower supine baroreflex sensitivity (p = 0.001) and high frequency heart rate variability (p = 0.03) than patients with postural orthostatic tachycardia syndrome. Patients with postural orthostatic tachycardia syndrome had lower upright high frequency heart rate variability (p < 0.001) and baroreflex sensitivity (p < 0.001) compared with patients without abnormalities and lower upright low frequency blood pressure variability (p = 0.04) compared with controls.

Conclusions: Patients with long-COVID have attenuated cardiac autonomic function. Patients with initial orthostatic hypotension have lower supine baroreflex sensitivity. Patients with postural orthostatic tachycardia syndrome have lower upright vascular sympathetic and cardiac parasympathetic modulation. Long-COVID subgroups do not present with homogeneous pathophysiology, necessitating targeted treatment strategies.

Introduction: Syncope is common, with bimodal distribution through life, peaking in adolescence and in the elderly, and overall increases in incidence with age among both men and women. In this context, syncope-related visits to emergency departments (ED), hospitalizations, and testing are a significant healthcare cost burden. Ultimately, understanding the volume of testing types and settings of syncope encounters may aid in more effective healthcare utilization and high value care for this patient population.

Methods: Data for this study were collected from the Truven Health Analytics MarketScan Database from 2006 to 2019. This database contains both commercially insured patients and those with Medicare coverage. Patients with the diagnosis of syncope were identified using International Classification of Diseases (ICD)-9 and -10 codes. We assessed the incidence of various tests for syncope evaluation and ED disposition for the study period.

Results: The incidence of syncope among the study cohort rose from nine per 1000 patients to 13 per 1000 patients during the study period. The incidence of testing for syncope among multiple domains (neurologic, cardiac, blood testing) decreased in some categories, but routine testing remained prevalent. Women had a significantly lower incidence of testing in most testing domains. Discharge rate from the ED for patients presenting with syncope remained stable during the study period. However, admission rate to the hospital for those aged > 65 years increased during the study time.

Conclusion: Testing and admissions for syncope remain prevalent and are drivers of healthcare-associated costs. There is a clear need for further work in developing a focused approach in the evaluation of syncope patients in order to mitigate healthcare costs and improve outcomes.