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1.
Epilepsy Behav ; 138: 109013, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36525923

RESUMO

OBJECTIVE: Temporal lobe epilepsy (TLE) is often associated with autonomic manifestations. Sudden unexpected death in epilepsy (SUDEP) is a leading cause of mortality in epilepsy. Cardiac disturbances and autonomic dysfunction are the potential mechanisms behind SUDEP. Though heart rate variability (HRV) and autonomic function tests are well studied in drug-resistant temporal lobe epilepsy, there is a paucity of data on baroreflex sensitivity (BRS), a better marker of cardiac mortality in this population. We aimed to study the interictal cardiac autonomic function and BRS in people living with drug-resistant temporal lobe epilepsy compared to healthy controls. MATERIALS AND METHODS: Thirty drug-resistant temporal lobe epilepsy (TLE) individuals and thirty healthy volunteers were recruited. Heart rate variability at rest, heart rate and blood pressure (BP) at rest, during deep breathing, postural change, BP response to isometric handgrip exercise, and baroreflex sensitivity were recorded in all study participants. The results were analyzed and compared between the two groups. RESULTS: Compared to controls, the resting heart rate, HRV, parasympathetic reactivity test, and BRS significantly differed in people living with drug-resistant TLE. Time-domain indices including SDNN (p < 0.001), RMSSD (p < 0.001), NN50 (p < 0.001), and pNN50 (p < 0.001) were significantly reduced in the patients compared to controls. In frequency-domain indices, the total power was reduced (p < 0.001) in drug-resistant TLE. The parasympathetic reactivity such as changes in heart rate during deep breathing (E: I) (p < 0.02) and postural change (30:15) (p < 0.005) were significantly reduced in the patients. Baroreflex sensitivity was also significantly reduced in the drug-resistant TLE group (p < 0.001). CONCLUSION: The present study findings are suggestive of parasympathetic dysfunction in drug-resistant TLE. Reduced HRV and BRS may increase the risk of SUDEP in people living with epilepsy.


Assuntos
Epilepsia Resistente a Medicamentos , Epilepsia do Lobo Temporal , Morte Súbita Inesperada na Epilepsia , Humanos , Barorreflexo/fisiologia , Epilepsia do Lobo Temporal/complicações , Força da Mão , Sistema Nervoso Autônomo , Frequência Cardíaca/fisiologia , Pressão Sanguínea/fisiologia
2.
J Clin Hypertens (Greenwich) ; 25(1): 22-29, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36545753

RESUMO

A relevant number of patients with resistant hypertension do not achieve blood pressure (BP) dipping during nighttime. This inadequate nocturnal BP reduction is associated with elevated cardiovascular risks. The aim of this study was to evaluate whether a nighttime intensification of BAT might improve nocturnal BP dipping. In this prospective observational study, non-dippers treated with BAT for at least 6 months were included. BAT programming was modified in a two-step intensification of nighttime stimulation at baseline and week 6. Twenty-four hours ambulatory BP (ABP) was measured at inclusion and after 3 months. A number of 24 patients with non- or inverted dipping pattern, treated with BAT for a median of 44 months (IQR 25-52) were included. At baseline of the study, patients were 66 ± 9 years old, had a BMI of 33 ± 6 kg/m2 , showed an office BP of 135 ± 22/72 ± 10 mmHg, and took a median number of antihypertensives of 6 (IQR 4-9). Nighttime stimulation of BAT was adapted by an intensification of pulse width from 237 ± 161 to 267 ± 170 µs (p = .003) while frequency (p = .10) and amplitude (p = .95) remained unchanged. Uptitration of BAT programming resulted in an increase of systolic dipping from 2 ± 6 to 6 ± 8% (p = .03) accompanied with a significant improvement of dipping pattern (p = .02). Twenty four hours ABP, day- and nighttime ABP remained unchanged. Programming of an intensified nighttime BAT interval improved dipping profile in patients treated with BAT, while the overall 24 h ABP did not change. Whether the improved dipping response contributes to a reduction of cardiovascular risk beyond the BP-lowering effects of BAT, however, remains to be shown.


Assuntos
Hipertensão , Humanos , Pessoa de Meia-Idade , Idoso , Hipertensão/complicações , Barorreflexo/fisiologia , Anti-Hipertensivos/uso terapêutico , Anti-Hipertensivos/farmacologia , Pressão Sanguínea/fisiologia , Estudos Prospectivos , Monitorização Ambulatorial da Pressão Arterial/métodos , Ritmo Circadiano/fisiologia
3.
Sci Rep ; 12(1): 22424, 2022 12 27.
Artigo em Inglês | MEDLINE | ID: mdl-36575245

RESUMO

Cardiovascular function is related to age, sex, and state of consciousness. We hypothesized that cardiovagal baroreflex sensitivity (BRS) demonstrates different patterns in both sexes before and after 50 years of age and that these patterns are associated with patterned changes during the sleep-wake cycle. We recruited 67 healthy participants (aged 20-79 years; 41 women) and divided them into four age groups: 20-29, 30-49, 50-69, and 70-79 years. All the participants underwent polysomnography and blood pressure measurements. For each participant, we used the average of the arterial pressure variability, heart rate variability (HRV), and BRS parameters during the sleep-wake stages. BRS and HRV parameters were significantly negatively correlated with age. The BRS indexes were significantly lower in the participants aged ≥ 50 years than in those aged < 50 years, and these age-related declines were more apparent during non-rapid eye movement sleep than during wakefulness. Only BRS demonstrated a significantly negative correlation with age in participants ≥ 50 years old. Women exhibited a stronger association than men between BRS and age and an earlier decline in BRS. Changes in BRS varied with age, sex, and consciousness state, each demonstrating a specific pattern. The age of 50 years appeared to be a crucial turning point for sexual dimorphism in BRS. Baroreflex modulation of the cardiovascular system during sleep sensitively delineated the age- and sex-dependent BRS patterns, highlighting the clinical importance of our results. Our findings may aid in screening for neurocardiac abnormalities in apparently healthy individuals.


Assuntos
Barorreflexo , Sistema Cardiovascular , Masculino , Humanos , Feminino , Adulto Jovem , Adulto , Pessoa de Meia-Idade , Barorreflexo/fisiologia , Sono/fisiologia , Polissonografia , Frequência Cardíaca/fisiologia , Pressão Sanguínea/fisiologia
4.
Sci Rep ; 12(1): 19279, 2022 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-36369521

RESUMO

Autonomic and vascular failures are common phenotypes of sepsis, typically characterized by tachycardia despite corrected hypotension/hypovolemia, vasopressor resistance, increased arterial stiffness and decreased peripheral vascular resistance. In a 5-day swine experiment of polymicrobial sepsis we aimed at characterizing arterial properties and autonomic mechanisms responsible for cardiovascular homeostasis regulation, with the final goal to verify whether the resuscitation therapy in agreement with standard guidelines was successful in restoring a physiological condition of hemodynamic profile, cardiovascular interactions and autonomic control. Twenty pigs were randomized to polymicrobial sepsis and protocol-based resuscitation or to prolonged mechanical ventilation and sedation without sepsis. The animals were studied at baseline, after sepsis development, and every 24 h during the 3-days resuscitation period. Beat-to-beat carotid blood pressure (BP), carotid blood flow, and central venous pressure were continuously recorded. The two-element Windkessel model was adopted to study carotid arterial compliance, systemic vascular resistance and characteristic time constant τ. Effective arterial elastance was calculated as a simple estimate of total arterial load. Cardiac baroreflex sensitivity (BRS) and low frequency (LF) spectral power of diastolic BP were computed to assess autonomic activity. Sepsis induced significant vascular and autonomic alterations, manifested as increased arterial stiffness, decreased vascular resistance and τ constant, reduced BRS and LF power, higher arterial afterload and elevated heart rate in septic pigs compared to sham animals. This compromised condition was persistent until the end of the experiment, despite achievement of recommended resuscitation goals by administered vasopressors and fluids. Vascular and autonomic alterations persist 3 days after goal-directed resuscitation in a clinically relevant sepsis model. We hypothesize that the addition of these variables to standard clinical markers may better profile patients' response to treatment and this could drive a more tailored therapy which could have a potential impact on long-term outcomes.


Assuntos
Sistema Nervoso Autônomo , Sepse , Animais , Sistema Nervoso Autônomo/fisiologia , Barorreflexo/fisiologia , Pressão Sanguínea/fisiologia , Artérias Carótidas , Frequência Cardíaca/fisiologia , Ressuscitação , Sepse/terapia , Suínos , Vasoconstritores
5.
Am J Physiol Heart Circ Physiol ; 323(6): H1206-H1211, 2022 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-36331556

RESUMO

Emerging evidence suggests that COVID-19 may affect cardiac autonomic function; however, the limited findings in young adults with COVID-19 have been equivocal. Notably, symptomology and time since diagnosis appear to influence vascular health following COVID-19, but this has not been explored in the context of cardiac autonomic regulation. Therefore, we hypothesized that young adults who had persistent symptoms following COVID-19 would have lower heart rate variability (HRV) and cardiac baroreflex sensitivity (BRS) compared with those who had COVID-19 but were asymptomatic at testing and controls who never had COVID-19. Furthermore, we hypothesized that there would be relationships between cardiac autonomic function measures and time since diagnosis. We studied 27 adults who had COVID-19 and were either asymptomatic (ASYM; n = 15, 6 females); 21 ± 4 yr; 8.4 ± 4.0 wk from diagnosis) or symptomatic (SYM; n = 12, 9 females); 24 ± 3 yr; 12.3 ± 6.2 wk from diagnosis) at testing, and 20 adults who reported never having COVID-19 (24 ± 4 yr, 11 females). Heart rate and beat-to-beat blood pressure were continuously recorded during 5 min of rest to assess HRV and cardiac BRS. HRV [root mean square of successive differences between normal heartbeats (RMSSD); control, 73 ± 50 ms; ASYM, 71 ± 47 ms; and SYM, 84 ± 45 ms; P = 0.774] and cardiac BRS (overall gain; control, 22.3 ± 10.1 ms/mmHg; ASYM, 22.7 ± 12.2 ms/mmHg; and SYM, 24.3 ± 10.8 ms/mmHg; P = 0.871) were not different between groups. However, we found correlations with time since diagnosis for HRV (e.g., RMSSD, r = 0.460, P = 0.016) and cardiac BRS (overall gain, r = 0.470, P = 0.014). These data suggest a transient impact of COVID-19 on cardiac autonomic function that appears mild and unrelated to persistent symptoms in young adults.NEW & NOTEWORTHY The potential role of persistent COVID-19 symptoms on cardiac autonomic function in young adults was investigated. We observed no differences in heart rate variability or cardiac baroreflex sensitivity between controls who never had COVID-19 and those who had COVID-19, regardless of symptomology. However, there were significant relationships between measures of cardiac autonomic function and time since diagnosis, suggesting that COVID-19-related changes in cardiac autonomic function are transient in young, otherwise healthy adults.


Assuntos
COVID-19 , Feminino , Adulto Jovem , Humanos , Sistema Nervoso Autônomo , Barorreflexo/fisiologia , Frequência Cardíaca/fisiologia , Coração , Pressão Sanguínea/fisiologia
7.
Int J Mol Sci ; 23(21)2022 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-36362405

RESUMO

Natriuretic peptides (NPs) induce vasodilation, natriuresis, and diuresis, counteract the renin-angiotensin-aldosterone system and autonomic nervous system, and are key regulators of cardiovascular volume and pressure homeostasis. Baroreflex afferent pathway is an important reflex loop in the neuroregulation of blood pressure (BP), including nodose ganglion (NG) and nucleus tractus solitarius (NTS). Dysfunction of baroreflex would lead to various hypertensions. Here, we carried out functional experiments to explore the effects of NPs on baroreflex afferent function. Under physiological and hypertensive condition (high-fructose drinking-induced hypertension, HFD), BP was reduced by NPs through NG microinjection and baroreflex sensitivity (BRS) was enhanced via acute intravenous NPs injection. These anti-hypertensive effects were more obvious in female rats with the higher expression of NPs and its receptor A/B (NPRA/NPRB) and lower expression of its receptor C (NPRC). However, these effects were not as obvious as those in HFD rats compared with the same gender control group, which is likely to be explained by the abnormal expression of NPs and NPRs in the hypertensive condition. Our data provide additional evidence showing that NPs play a crucial role in neurocontrol of BP regulation via baroreflex afferent function and may be potential targets for clinical management of metabolic-related hypertension.


Assuntos
Barorreflexo , Hipertensão , Feminino , Animais , Ratos , Barorreflexo/fisiologia , Pressão Sanguínea , Ratos Sprague-Dawley , Vias Aferentes/fisiologia , Hipertensão/metabolismo , Peptídeos Natriuréticos/metabolismo
8.
Folia Med Cracov ; 62(3): 111-122, 2022 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-36309836

RESUMO

BACKGROUND: Autonomic dysfunction, impaired baroreflex sensitivity (BRS), and deranged circulatory homeostasis have been observed in chronic hyperglycemia and found to be associated with increased cardiovascular morbidity and mortality. However, the acute effects of hyperglycemia in healthy subjects have been rarely studied. The present study explores the effect of acute hyperglycemia on conventional and unconventional parameters of BRS in healthy young adults. METHODS: For the estimation of BRS beat-to-beat blood pressure (BP) and electrocardiogram were recorded in forty-two young, healthy subjects during fasting and at 1hr of the oral glucose load. Analysis of BRS was carried out by sequence and spectral method. Number of UP-, DOWN- and ALL-sequences between ramps of BP and RR-interval were calculated as an unconventional measure of BRS along with the other conventional parameters. RESULTS: We observed significant alteration of unconventional parameters of autonomic functions [the number of sequences of UP- (p = 0.0039) and ALL-sequences (p = 0.0233) of systolic BP and RR interval; and, UP- (p = 0.0380), DOWN- (p = 0.0417) and ALL-sequences (p = 0.0313) of mean BP and RR- interval] during acute hyperglycemia as compared to the fasting state. However, no significant changes were observed in any of the conventional parameters of BRS during acute hyperglycemia as compared to the fasting state. CONCLUSIONS: Present study concludes that the unconventional parameters of BRS - the number of sequences between the ramp of BP and RR-interval - change significantly during acute hyperglycemia. However, the conventional parameters do not show significant changes during acute hyperglycemia. We may hypothesize that the relatively constant BRS is maintained at the expense of increased oscillations in the ramp of BP and RR-interval.


Assuntos
Barorreflexo , Hiperglicemia , Adulto Jovem , Humanos , Barorreflexo/fisiologia , Frequência Cardíaca/fisiologia , Pressão Sanguínea/fisiologia , Eletrocardiografia , Doença Aguda
9.
Am J Physiol Regul Integr Comp Physiol ; 323(6): R910-R920, 2022 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-36250861

RESUMO

Large body mass (Mb) in vertebrates is associated with longer pulse intervals between heartbeats (PI) and thicker arterial walls. Longer PI increases the time for diastolic pressure decay, possibly resulting in loss of cardiac energy as "oscillatory power," whereas thicker arterial walls may affect the transmission of impulses and sensing of pressure fluctuations thus impairing baroreflex function. We aimed to investigate the effect of growth on the relative cardiac energy loss and baroreflex function. We predicted that 1) the relative use of cardiac energy should be preserved with increased time constant for pressure decay (τ = vascular resistance × compliance) and 2) if arterial circumferential distensibility does not change, baroreflex function should be unaltered with Mb. To test these hypotheses, we used green iguanas (Iguana iguana) weighing from 0.03 to 1.34 kg (43-fold increment in Mb). PI (P = 0.037) and τ (P = 0.035) increased with Mb, whereas the oscillatory power fraction (P = 0.245) was unrelated to it. Thus, the concomitant alterations of τ and PI allowed the conservation of cardiac energy in larger lizards. Larger animals had thicker arterial walls (P = 0.0007) and greater relative collagen content (P = 0.022). Area compliance scaled positively to Mb (P = 0.045), though circumferential distensibility (P = 0.155) and elastic modulus (P = 0.762) were unaltered. In addition, baroreflex sensitivity, measured by both the pharmacological (P = 0.152) and sequence methods (P = 0.088), and the baroreflex effectiveness index (P = 0.306) were also unrelated to Mb. Therefore, changes in arterial morphology did not affect circumferential distensibility and presumably sensing of pressure fluctuation, and the cardiovagal baroreflex is preserved across different Mb.


Assuntos
Barorreflexo , Iguanas , Animais , Barorreflexo/fisiologia , Iguanas/anatomia & histologia , Iguanas/fisiologia , Frequência Cardíaca , Pressão Sanguínea/fisiologia , Coração
10.
Ther Adv Cardiovasc Dis ; 16: 17539447221131203, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36305639

RESUMO

PURPOSE: Baroreflex activation therapy has favorable effects in heart failure patients. We report the results of a single-center study of baroreflex activation therapy in heart failure with reduced ejection fraction including cardiopulmonary exercise testing for the first time to show the effect on exercise capacity. METHODS: A total of 17 patients were treated with baroreflex activation therapy. Eligibility criteria were the New York Heart Association class ⩾III and ejection fraction ⩽35% on guideline-directed medical and device therapy. The New York Heart Association class, quality of life, and 6-min hall walk distance were assessed in all patients. Twelve patients underwent cardiopulmonary exercise testing before and 8.9 ± 6.4 months after initiation of baroreflex activation therapy. RESULTS: The New York Heart Association class and 6-min hall walk distance improved after baroreflex activation therapy, while quality of life remained stable. Weight-adapted peak oxygen uptake increased significantly from 10.1 (8.2-12.9) ml/min/kg to 12.1 (10.4-14.6) ml/min/kg (p = 0.041). Maximal heart rate was stable. Maximal oxygen pulse increased from 9.7 (5.5-11.3) to 9.9 (7.1-12.1) ml/heartbeat (p = 0.047) in 10 patients with low maximal oxygen pulse at baseline (<16.5 ml/heartbeat). There was no significant change in maximal oxygen pulse in the whole cohort. Ventilatory efficiency remained stable. CONCLUSION: Weight-adapted peak oxygen uptake improved after baroreflex activation therapy, pointing to an enhanced exercise capacity. Ventilatory efficiency and heart rate did not change, while oxygen pulse increased in patients with low oxygen pulse at baseline, indicating an improvement in circulatory efficiency, that is, a beneficial effect on stroke volume and peripheral oxygen extraction.


Assuntos
Terapia por Estimulação Elétrica , Insuficiência Cardíaca , Disfunção Ventricular Esquerda , Humanos , Barorreflexo/fisiologia , Volume Sistólico/fisiologia , Qualidade de Vida , Terapia por Estimulação Elétrica/métodos , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/terapia , Teste de Esforço , Oxigênio , Tolerância ao Exercício
11.
Am J Physiol Regul Integr Comp Physiol ; 323(5): R720-R727, 2022 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-36121147

RESUMO

Rapid regulation of arterial blood pressure on a beat-by-beat basis occurs primarily via arterial baroreflex control of cardiac output (CO) via rapid changes in heart rate (HR). Previous studies have shown that changes in HR do not always cause changes in CO, because stroke volume may vary. Whether these relationships are altered in hypertension is unknown. Using the spontaneous baroreflex sensitivity (SBRS) approach, we investigated whether baroreflex control of HR and CO were impaired after the induction of hypertension in conscious, chronically instrumented canines at rest, during mild exercise, and during exercise with metaboreflex activation (induced via reductions in hindlimb blood flow) both before and after induction of hypertension (induced via a modified Goldblatt approach-unilateral reduction in renal blood flow to ∼30% of control values until systolic pressure ≥ 140 mmHg and a diastolic pressure ≥ 90 mmHg for >30 days). After induction of hypertension, SBRS control of both HR and CO was reduced in all settings. In control, only about 50% of SBRS changes in HR caused changes in CO. This pattern was sustained in hypertension. Thus, in hypertension, the reduced SBRS in the control of HR caused reduced SBRS control of CO and this likely contributes to the increased incidence of orthostatic hypotension seen in hypertensive patients.


Assuntos
Barorreflexo , Hipertensão , Cães , Animais , Barorreflexo/fisiologia , Frequência Cardíaca/fisiologia , Músculo Esquelético/fisiologia , Débito Cardíaco/fisiologia , Pressão Sanguínea/fisiologia
12.
Physiol Rep ; 10(18): e15423, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-36151607

RESUMO

Cross-sectional data indicate that acute SARS-CoV-2 infection increases resting muscle sympathetic nerve activity (MSNA) and alters hemodynamic responses to orthostasis in young adults. However, the longitudinal impact of contracting SARS-CoV-2 on autonomic function remains unclear. The aim of this study was to longitudinally track MSNA, sympathetic transduction to blood pressure (BP), and hemodynamics over 6 months following SARS-CoV-2 infection. Young adults positive with SARS-CoV-2 reported to the laboratory three times over 6 months (V1:41 ± 17, V2:108 ± 21, V3:173 ± 16 days post-infection). MSNA, systolic (SBP) and diastolic (DBP) blood pressure, and heart rate (HR) were measured at rest, during a cold pressor test (CPT), and at 30° head-up tilt (HUT). Basal SBP (p = 0.019) and DBP (p < 0.001) decreased throughout the 6 months, whereas basal MSNA and HR were not different. Basal sympathetic transduction to BP and estimates of baroreflex sensitivity did not change over time. SBP and DBP were lower during CPT (SBP: p = 0.016, DBP: p = 0.007) and HUT at V3 compared with V1 (SBP: p = 0.041, DBP: p = 0.017), with largely no changes in MSNA. There was a trend toward a visit-by-time interaction for burst incidence (p = 0.055) during HUT, wherein at baseline immediately prior to tilting, burst incidence was lower at V3 compared with V1 (p = 0.014), but there were no differences between visits in the 30 HUT position. These results support impairments to cardiovascular health, and potentially autonomic function, which may improve over time. However, the improvements in BP over 6 months recovery from mild SARS-CoV-2 infection are likely not a direct result of changes in sympathetic activity.


Assuntos
COVID-19 , Barorreflexo/fisiologia , Pressão Sanguínea/fisiologia , Estudos Transversais , Frequência Cardíaca/fisiologia , Hemodinâmica/fisiologia , Humanos , Músculo Esquelético/fisiologia , SARS-CoV-2 , Sistema Nervoso Simpático/fisiologia , Adulto Jovem
13.
Biomech Model Mechanobiol ; 21(6): 1903-1917, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36107358

RESUMO

Multiscale models of the cardiovascular system can provide new insights into physiological and pathological processes. PyMyoVent is a computer model that bridges from molecular- to organ-level function and which simulates a left ventricle pumping blood through the systemic circulation. Initial work with PyMyoVent focused on the end-systolic pressure volume relationship and ranked potential therapeutic strategies by their impact on contractility. This manuscript extends the PyMyoVent framework by adding closed-loop feedback control of arterial pressure. The control algorithm mimics important features of the physiological baroreflex and was developed as part of a long-term program that focuses on growth and biological remodeling. Inspired by the underlying biology, the reflex algorithm uses an afferent signal derived from arterial pressure to drive a kinetic model that mimics the net result of neural processing in the medulla and cell-level responses to autonomic drive. The kinetic model outputs control signals that are constrained between limits that represent maximum parasympathetic and maximum sympathetic drive and which modulate heart rate, intracellular Ca2+ dynamics, the molecular-level function of both the thick and the thin myofilaments, and vascular tone. Simulations show that the algorithm can regulate mean arterial pressure at user-defined setpoints as well as maintaining arterial pressure when challenged by changes in blood volume and/or valve resistance. The reflex also regulates arterial pressure when cell-level contractility is modulated to mimic the idealized impact of myotropes. These capabilities will be important for future work that uses computer modeling to investigate clinical conditions and treatments.


Assuntos
Barorreflexo , Sistema Cardiovascular , Barorreflexo/fisiologia , Pressão Arterial , Pressão Sanguínea/fisiologia , Frequência Cardíaca/fisiologia
14.
Braz J Med Biol Res ; 55: e12150, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36102416

RESUMO

The intracranial compliance in type 2 diabetes mellitus (T2DM) patients and the association with cardiovascular autonomic control have not been fully elucidated. The aim of this study was to assess intracranial compliance using the noninvasive intracranial pressure (niICP) and the monitoring of waveform peaks (P1, P2, and P3) and the relationship with cardiovascular autonomic control in T2DM patients. Thirty-two men aged 40-60 years without cardiovascular autonomic neuropathy (CAN) were studied: T2DMG (n=16) and control group CG (n=16). The niICP was evaluated by a noninvasive extracranial sensor placed on the scalp. Cardiovascular autonomic control was evaluated by indices of the baroreflex sensitivity (BRS), from temporal series of R-R intervals of electrocardiogram and systolic arterial pressure, during supine and orthostatic positions. The participants remained in the supine position for 15 min and then 15 min more in orthostatism. T2DMG presented a decrease of the P2/P1 ratio during the orthostatic position (P<0.001). There was a negative moderate correlation between the P2 peak with cardiovascular coupling (K2HP-SAPLF) in supine (r=-0.612, P=0.011) and orthostatic (r=-0.568, P=0.020) positions in T2DMG. We concluded that T2DM patients without CAN and cardiovascular complications presented intracranial compliance similar to healthy subjects. Despite preserved intracranial adjustments, T2DM patients had a response of greater magnitude in orthostatism. In addition, the decoupling between the heart period and blood pressure signal oscillations in low frequency appeared to be related to the worsening of intracranial compliance due to the increased P2 peak.


Assuntos
Diabetes Mellitus Tipo 2 , Sistema Nervoso Autônomo/fisiologia , Barorreflexo/fisiologia , Pressão Sanguínea/fisiologia , Diabetes Mellitus Tipo 2/complicações , Coração , Humanos , Masculino
15.
Zhongguo Yi Xue Ke Xue Yuan Xue Bao ; 44(4): 717-721, 2022 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-36065707

RESUMO

Heart failure (HF) is the endstage of multiple cardiovascular diseases.Impaired autonomic regulation and sympathetic-parasympathetic imbalance are considered key factors in HF progression.Baroreflex activation therapy (BAT),a novel device-based therapy which stimulates the carotid sinuses and regulates autonomic function,has demonstrated good efficacy in treating HF and improving prognosis.This review summarized the results of the latest relevant studies to provide support for further study of BAT.


Assuntos
Barorreflexo , Insuficiência Cardíaca , Barorreflexo/fisiologia , Insuficiência Cardíaca/terapia , Humanos
16.
Annu Int Conf IEEE Eng Med Biol Soc ; 2022: 1402-1405, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-36086234

RESUMO

Fluid administration is one of the most common therapies performed on intensive care patients. However, no clinical evidence is available to establish optimal strategies for fluid management as well as characterizing the effects on the cardiovascular system after therapy initiation. Moreover, fluid overload showed a correlation with worse clinical outcomes. This study aims at characterizing the response to the fluid intervention of intensive care unit patients. We extracted a population of 57 subjects with available electrocardiogram and arterial blood pressure recordings from the MIMIC-III database and evaluated the induced changes in cardiovascular and autonomic indices. We compare autonomic indices obtained from a statistical model of heartbeat dynamics before and after the intervention. Results show significant differences in RR interval, blood pressure, autonomic and Baroreflex activities up to 60 minutes after fluid administration. Specifically, we observed a median increase in RR interval, Baroreflex activity, and overall activity both in pressure and RR time series, as well as a reduction in systolic blood pressure. Specifically, a subgroup of survived patients shows an imbalance toward sympathetic activity, whereas non-survivors have a persistent vagal state after fluid administration. Clinical relevance - The observed differences in autonomic response after fluid administration, together with the assessment of their correlation with patients' mortality, paves the way for the inclusion of heart rate variability indices as markers for assessing fluid responsiveness as associated with ICU patients' state.


Assuntos
Sistema Nervoso Autônomo , Barorreflexo , Sistema Nervoso Autônomo/fisiologia , Barorreflexo/fisiologia , Pressão Sanguínea/fisiologia , Frequência Cardíaca/fisiologia , Humanos , Unidades de Terapia Intensiva
17.
JACC Heart Fail ; 10(9): 662-676, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-36049816

RESUMO

BACKGROUND: Novel treatments targeting in baroreflex sensitivity (BRS) and chemoreflex sensitivity (CRS) heart failure (HF) are grounded on small prognostic studies, partly performed in the pre-beta-blockade era. OBJECTIVES: This study assesses the clinical/prognostic significance of BRS and CRS in a large cohort of patients with chronic HF on modern treatments. METHODS: Outpatients with chronic HF with either reduced (≤40%) or mildly reduced left ventricular ejection fraction (LVEF) (41% to 49%) underwent BRS (SD method) and CRS to hypoxia and hypercapnia (rebreathing technique) assessment and were followed up for a composite endpoint of cardiac death, implantable cardioverter-defibrillator shock, or HF hospitalization. RESULTS: A total of 425 patients were enrolled (65 ± 12 years of age, LVEF 32% [IQR: 25%-38%], 94% on beta blockers). Patients with decreased BRS (n = 96 of 267, 36%) had lower exercise tolerance and heart rate variability (P < 0.05), whereas those with increased CRS to both hypoxia and hypercapnia (n = 74 of 369, 20%) had higher plasma norepinephrine and central apneas across the 24-hour period (P < 0.01). During a median 50-month follow-up (IQR: 24-94 months), the primary endpoint occurred more often in patients with decreased BRS (log-rank: 11.64; P = 0.001), mainly for increased cardiac deaths/implantable cardioverter-defibrillator shocks, and in those with increased CRS (log-rank: 34.81; P < 0.001), mainly for increased HF hospitalizations. Patients with both abnormal BRS and CRS showed the worst outcome. Reduced BRS (HR: 2.76 [95% CI: 1.36-5.63]; P = 0.005) and increased CRS (HR: 2.91 [95% CI: 1.34-6.31]; P = 0.007) were independently associated with the primary outcome and increased risk stratification when added to standard HF prognosticators (P < 0.05). CONCLUSIONS: In subjects with HF on modern treatment, abnormal BRS and CRS are frequently observed. BRS and CRS elicit autonomic imbalance, exercise limitation, unstable ventilation, and predict adverse outcomes.


Assuntos
Barorreflexo , Insuficiência Cardíaca , Barorreflexo/fisiologia , Insuficiência Cardíaca/terapia , Frequência Cardíaca/fisiologia , Humanos , Hipercapnia , Hipóxia , Prognóstico , Volume Sistólico/fisiologia , Função Ventricular Esquerda/fisiologia
18.
J Appl Physiol (1985) ; 133(4): 867-875, 2022 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-35952348

RESUMO

Repeat exposures to low oxygen (intermittent hypoxia, IH), like that observed in sleep apnea, elicit increases in muscle sympathetic nerve activity (MSNA) and blood pressure (BP) in men. Endothelin (ET) receptor antagonists can attenuate the sympathetic and BP response to IH in rodents; whether these data translate to humans are unclear. We hypothesized that ET-receptor antagonism would ameliorate any rise in MSNA and BP following acute IH in humans. Twelve healthy men (31 ± 1 yr) completed two visits (control, bosentan) separated by at least 1 wk. MSNA, BP, and baroreflex sensitivity (modified Oxford) were assessed during normoxic rest before and following 30 min of IH. The midpoint (T50) for each individual's baroreflex curve was calculated. Acute IH increased plasma ET-1 (P < 0.01), MSNA burst frequency (P = 0.03), and mean BP (P < 0.01). There was no effect of IH on baroreflex sensitivity (P = 0.46), although an increase in T50 was observed (P < 0.01). MSNA burst frequency was higher (P = 0.04) and mean BP (P < 0.01) was lower following bosentan treatment compared with control. There was no effect of bosentan on baroreflex sensitivity (P = 0.53), although a lower T50 was observed on the bosentan visit (P < 0.01). There was no effect of bosentan on increases in MSNA (P = 0.81) or mean BP (P = 0.12) following acute IH. Acute IH results in an increase in ET-1, MSNA, and BP in healthy young men. The effect of IH on MSNA and BP is not attenuated following ET-receptor inhibition. Present data suggest that acute IH does not increase MSNA or BP through activation of ET-receptors in healthy young men.NEW & NOTEWORTHY Repeat exposures to low oxygen (intermittent hypoxia, IH) elicit increases in muscle sympathetic nerve activity (MSNA) and blood pressure (BP) in men. Endothelin (ET) receptor antagonists can attenuate the sympathetic and BP response to IH in rodents; whether these data translate to humans were unclear. We show acute IH results in an increase in ET-1, MSNA, and BP in healthy young men; however, the effect of IH on MSNA and BP does not occur through activation of ET-receptors in healthy young men.


Assuntos
Barorreflexo , Sistema Nervoso Simpático , Barorreflexo/fisiologia , Pressão Sanguínea/fisiologia , Bosentana , Endotelina-1 , Endotelinas , Frequência Cardíaca/fisiologia , Hemodinâmica , Humanos , Hipóxia , Masculino , Músculo Esquelético , Oxigênio , Receptor de Endotelina A , Sistema Nervoso Simpático/fisiologia
19.
J R Soc Interface ; 19(193): 20220220, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-36000360

RESUMO

Patients with postural orthostatic tachycardia syndrome (POTS) experience an excessive increase in heart rate (HR) and low-frequency (∼0.1 Hz) blood pressure (BP) and HR oscillations upon head-up tilt (HUT). These responses are attributed to increased baroreflex (BR) responses modulating sympathetic and parasympathetic signalling. This study uses a closed-loop cardiovascular compartment model controlled by the BR to predict BP and HR dynamics in response to HUT. The cardiovascular model predicts these quantities in the left ventricle, upper and lower body arteries and veins. HUT is simulated by letting gravity shift blood volume (BV) from the upper to the lower body compartments, and the BR control is modelled using set-point functions modulating peripheral vascular resistance, compliance, and cardiac contractility in response to changes in mean carotid BP. We demonstrate that modulation of parameters characterizing BR sensitivity allows us to predict the persistent increase in HR and the low-frequency BP and HR oscillations observed in POTS patients. Moreover, by increasing BR sensitivity, inhibiting BR control of the lower body vasculature, and decreasing central BV, we demonstrate that it is possible to simulate patients with neuropathic and hyperadrenergic POTS.


Assuntos
Síndrome da Taquicardia Postural Ortostática , Barorreflexo/fisiologia , Pressão Sanguínea/fisiologia , Frequência Cardíaca/fisiologia , Humanos , Postura/fisiologia
20.
Auton Neurosci ; 242: 103021, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-35985253

RESUMO

We present a framework for the linear parametric analysis of pairwise interactions in bivariate time series in the time and frequency domains, which allows the evaluation of total, causal and instantaneous interactions and connects time- and frequency-domain measures. The framework is applied to physiological time series to investigate the cerebrovascular regulation from the variability of mean cerebral blood flow velocity (CBFV) and mean arterial pressure (MAP), and the cardiovascular regulation from the variability of heart period (HP) and systolic arterial pressure (SAP). We analyze time series acquired at rest and during the early and late phase of head-up tilt in subjects developing orthostatic syncope in response to prolonged postural stress, and in healthy controls. The spectral measures of total, causal and instantaneous coupling between HP and SAP, and between MAP and CBFV, are averaged in the low-frequency band of the spectrum to focus on specific rhythms, and over all frequencies to get time-domain measures. The analysis of cardiovascular interactions indicates that postural stress induces baroreflex involvement, and its prolongation induces baroreflex dysregulation in syncope subjects. The analysis of cerebrovascular interactions indicates that the postural stress enhances the total coupling between MAP and CBFV, and challenges cerebral autoregulation in syncope subjects, while the strong sympathetic activation elicited by prolonged postural stress in healthy controls may determine an increased coupling from CBFV to MAP during late tilt. These results document that the combination of time-domain and spectral measures allows us to obtain an integrated view of cardiovascular and cerebrovascular regulation in healthy and diseased subjects.


Assuntos
Sistema Cardiovascular , Síncope , Barorreflexo/fisiologia , Pressão Sanguínea/fisiologia , Circulação Cerebrovascular/fisiologia , Coração/fisiologia , Frequência Cardíaca/fisiologia , Humanos
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