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MedRxiv : the Preprint Server For... May 2024Individuals with spinal cord injury (SCI) commonly have autonomic dysreflexia (AD) with increased sympathetic activity. After SCI, individuals have decreased baroreflex...
Why do different people with Spinal Cord Injury have differing severity of symptoms with Autonomic Dysreflexia? Exploring relationships of vascular alpha-1 adrenoreceptor and baroreflex sensitivity after SCI.
INTRODUCTION
Individuals with spinal cord injury (SCI) commonly have autonomic dysreflexia (AD) with increased sympathetic activity. After SCI, individuals have decreased baroreflex sensitivity and increased vascular responsiveness.
OBJECTIVE
To evalate relationship between baroreflex and blood vessel sensitivity with autonomic dysreflexia symptoms.
DESIGN
Case control.
SETTING
Tertiary academic center.
PATIENTS
14 individuals with SCI, 17 matched uninjured controls.
INTERVENTIONS
All participants quantified AD symptoms using the Autonomic Dysfunction Following SCI (ADFSCI)-AD survey. Participants received three intravenous phenylephrine boluses, reproducibly increasing systolic blood pressure (SBP) 15-40 mmHg. Continuous heart rate (R-R interval, ECG), beat-to-beat blood pressures (finapres), and popliteal artery flow velocity were recorded. Vascular responsiveness (α1 adrenoreceptor sensitivity) and heart rate responsiveness to increased SBP (baroreflex sensitivity) were calculated.
MAIN OUTCOME MEASURES
Baroreflex sensitivity after increased SBP; Vascular responsiveness through quantified mean arterial pressure (MAP) 2-minute area under the curve and change in vascular resistance.
RESULTS
SCI and control cohorts were well-matched with mean age 31.9 and 29.6 years (p=0.41), 21.4% and 17.6% female respectively. Baseline MAP (p=0.83) and R-R interval (p=0.39) were similar. ADFSCI-AD scores were higher following SCI (27.9+/-22.9 vs 4.2+/-2.9 in controls, p=0.002). To quantify SBP response, MAP area under the curve was normalized to dose/bodyweight. Individuals with SCI had significantly larger responses (0.26+/-0.19 mmHg*s/kg*ug) than controls (0.06+/-0.06 mmHg*s/kg*ug, p=0.002). Similarly, leg vascular resistance increased after SCI (24% vs 6% to a normalized dose, p=0.007). Baroreflex sensitivity was significantly lower after SCI (15.0+/-8.3 vs 23.7+/-9.3 ms/mmHg, p=0.01). ADFSCI-AD subscore had no meaningful correlation with vascular responsiveness (R =0.008) or baroreflex sensitivity (R =0.092) after SCI.
CONCLUSIONS
While this confirms smaller previous studies suggesting increased α1 adrenoreceptor sensitivity and lower baroreflex sensitivity in individuals with SCI, these differences lacked correlation to increased symptoms of AD. Further research into physiologic mechanisms to explain why some individuals with SCI develop symptoms is needed.
PubMed: 38746296
DOI: 10.1101/2024.05.02.24306772 -
Frontiers in Neuroscience 2024Sleep insufficiency has been linked to an increased risk of high blood pressure and cardiovascular diseases. Emerging studies have demonstrated that impaired baroreflex...
INTRODUCTION
Sleep insufficiency has been linked to an increased risk of high blood pressure and cardiovascular diseases. Emerging studies have demonstrated that impaired baroreflex sensitivity (BRS) is involved in the adverse cardiovascular effects caused by sleep deprivation, however, the underlying mechanisms remain unknown. Therefore, the present study aims to clarify the role of abnormal renin-angiotensin system in the nucleus tractus solitarii (NTS) in impaired BRS induced by sleep deprivation.
METHODS
Rats were randomly divided into two groups: normal sleep (Ctrl) and chronic sleep deprivation (CSD) group. Rats were sleep deprived by an automated sleep deprivation system. The blood pressure, heart rate, BRS, the number of c-Fos positive cells and the expression of angiotensin (Ang) II subtype 1 receptors (AT1R) in the NTS of rats were assessed.
RESULTS
Compared to Ctrl group, CSD group exhibited a higher blood pressure, heart rate, and reduced BRS. Moreover, the number of c-Fos positive cells and local field potential in the NTS in CSD group were increased compared with the Ctrl group. It was shown that the expression of the AT1R and the content of Ang II and the ratio of Ang II to Ang-(1-7) were increased in the NTS of rats in CSD group compared to Ctrl group. In addition, microinjection of losartan into the NTS significantly improved the impaired BRS caused by sleep deprivation.
DISCUSSION
In conclusion, these data suggest that the elevated AT1R expression in the NTS mediates the reduced BRS induced by chronic sleep deprivation.
PubMed: 38741786
DOI: 10.3389/fnins.2024.1401530 -
Journal of Clinical Medicine Apr 2024: Autonomic function and baroreflex control might influence the survival rate of coronavirus disease 2019 (COVID-19) patients admitted to the intensive care unit (ICU)...
: Autonomic function and baroreflex control might influence the survival rate of coronavirus disease 2019 (COVID-19) patients admitted to the intensive care unit (ICU) compared to respiratory failure patients without COVID-19 (non-COVID-19). This study describes physiological control mechanisms in critically ill COVID-19 patients admitted to the ICU in comparison to non-COVID-19 individuals with the aim of improving stratification of mortality risk. : We evaluated autonomic and baroreflex control markers extracted from heart period (HP) and systolic arterial pressure (SAP) variability acquired at rest in the supine position (REST) and during a modified head-up tilt (MHUT) in 17 COVID-19 patients (age: 63 ± 10 years, 14 men) and 33 non-COVID-19 patients (age: 60 ± 12 years, 23 men) during their ICU stays. Patients were categorized as survivors (SURVs) or non-survivors (non-SURVs). : We found that COVID-19 and non-COVID-19 populations exhibited similar vagal and sympathetic control markers; however, non-COVID-19 individuals featured a smaller baroreflex sensitivity and an unexpected reduction in the HP-SAP association during the MHUT compared to the COVID-19 group. Nevertheless, none of the markers of the autonomic and baroreflex functions could distinguish SURVs from non-SURVs in either population. : We concluded that COVID-19 patients exhibited a more preserved baroreflex control compared to non-COVID-19 individuals, even though this information is ineffective in stratifying mortality risk.
PubMed: 38673501
DOI: 10.3390/jcm13082228 -
Circulation Apr 2024
Topics: NAV1.7 Voltage-Gated Sodium Channel; Humans; Autonomic Nervous System Diseases; Sodium Channel Blockers; Male; Voltage-Gated Sodium Channel Blockers
PubMed: 38648272
DOI: 10.1161/CIRCULATIONAHA.123.067331 -
American Journal of Physiology.... Apr 2024Post-exercise reduction in blood pressure, termed post-exercise hypotension (PEH), is relevant for both acute and chronic health reasons and potentially for peripheral...
Post-exercise reduction in blood pressure, termed post-exercise hypotension (PEH), is relevant for both acute and chronic health reasons and potentially for peripheral cardiovascular adaptations. We investigated the interactive effects of exercise intensity and recovery postures (seated, supine, and standing) on PEH. Thirteen normotensive men underwent a VO test on a cycle ergometer and 5 exhaustive constant load trials to determine critical power (CP) and the gas exchange threshold (GET). Subsequently, work-matched exercise trials were performed at two discrete exercise intensities (10% > CP and 10% < GET), with one hour of recovery in each of three postures. For both exercise intensities, standing posture resulted in a more substantial PEH (all < 0.01). For both standing and seated recovery postures, the higher exercise intensity led to larger reductions in systolic, diastolic and mean arterial pressures (all < 0.01), whereas in the supine recovery posture, the reduction in diastolic and mean arterial pressures was unaffected by prior exercise intensity (both > 0.05). PEH is more pronounced during recovery from exercise performed above critical power versus below GET. However, the effect of exercise intensity on PEH is largely abolished when recovery is performed in the supine posture.
PubMed: 38646812
DOI: 10.1152/ajpregu.00036.2024 -
Cureus Mar 2024Autonomic nervous system (ANS) regulation in hereditary angioedema (HAE) and coronavirus disease 2019 (COVID-19) is unknown. ANS alterations could be manifested during...
Autonomic nervous system (ANS) regulation in hereditary angioedema (HAE) and coronavirus disease 2019 (COVID-19) is unknown. ANS alterations could be manifested during both the acute and post-acute phases of COVID-19. Implications of acute and chronic inflammation on ANS in HAE need to be addressed. In this case report, we monitored the systolic arterial blood pressure variability and baroreflex sensitivity in a female HAE patient both before experiencing COVID-19 symptoms and one month afterward. We also tracked the heart rate variability on the day preceding symptom onset, the day of symptom onset (SYM), the day following SYM, five days after SYM, the day of the first negative nasopharyngeal swab (i.e., 12 days after SYM), and one month after symptom onset. The results of this case report provide the characterization of vascular and cardiac autonomic profiles in an HAE patient until the resolution of an acute infection, a potential trigger for the acute HAE attack.
PubMed: 38638792
DOI: 10.7759/cureus.56449 -
The Ultrasound Journal Apr 2024Subarachnoid hemorrhage (SAH) patients with cerebral autoregulation (CA) impairment at an early post-SAH period are at high risk of unfavorable outcomes due to delayed...
Impaired cerebral autoregulation detected in early prevasospasm period is associated with unfavorable outcome after spontaneous subarachnoid hemorrhage: an observational prospective pilot study.
BACKGROUND
Subarachnoid hemorrhage (SAH) patients with cerebral autoregulation (CA) impairment at an early post-SAH period are at high risk of unfavorable outcomes due to delayed cerebral ischemia (DCI) or other complications. Limited evidence exists for an association between early-stage CA impairments and SAH patient outcomes. The objective of this prospective study was to explore associations between CA impairments detected in early post-SAH snapshot examinations and patient outcomes.
METHODS
The pilot observational study included 29 SAH patients whose CA status was estimated 2-3 days after spontaneous aneurysm rupture and a control group of 15 healthy volunteers for comparison. Inflatable leg recovery boots (reboots.com, Germany) were used for the safe controlled generation of arterial blood pressure (ABP) changes necessary for reliable CA examination. At least 5 inflation‒deflation cycles of leg recovery boots with a 2-3 min period were used during examinations. CA status was assessed according to the delay time (∆T) measured between ABP(t) and cerebral blood flow velocity (CBFV(t)) signals during artificially induced ABP changes at boot deflation cycle. CBFV was measured in middle cerebral artery by using transcranial Doppler device.
RESULTS
Statistically significant differences in ∆T were found between SAH patients with unfavorable outcomes (∆T = 1.37 ± 1.23 s) and those with favorable outcomes (∆T = 2.86 ± 0.99 s) (p < 0.001). Early assessment of baroreflex sensitivity (BRS) during the deflation cycle showed statistically significant differences between the DCI and non-DCI patient groups (p = 0.039).
CONCLUSIONS
A relatively small delay of ∆T <1.6 s between CBFV(t) and ABP(t) waves could be an early warning sign associated with unfavorable outcomes in SAH patients. The BRS during boot deflation can be used as a biomarker for the prediction of DCI.
TRIAL REGISTRATION
ClinicalTrials.gov Identifier: NCT06028906. Registered 31 August 2023 - Retrospectively registered, https://www.
CLINICALTRIALS
gov/study/NCT06028906 .
PubMed: 38619783
DOI: 10.1186/s13089-024-00371-8 -
Beijing Da Xue Xue Bao. Yi Xue Ban =... Apr 2024Afferent baroreflex failure (ABF) is a rare disease. It refers to the clinical syndrome caused by the impairment of the afferent limb of the baroreflex or its central...
Afferent baroreflex failure (ABF) is a rare disease. It refers to the clinical syndrome caused by the impairment of the afferent limb of the baroreflex or its central connections at the level of the medulla. The recognized causes include trauma, surgery in related areas (radical neck tumor surgery, carotid endarterectomy), neck radiotherapy, brain stem stroke, tumor growth paraganglioma and hereditary diseases, among which the most common cause is extensive neck surgery or radiotherapy for neck cancer. The main manifestations are fluctuating hypertension, orthostatic hypotension, paroxysmal tachycardia and bradycardia. This case is a young man, whose main feature is blood pressure fluctuation, accom-panied by neurogenic orthostatic hypotension (nOH). After examination, the common causes of hypertension and nOH were ruled out. Combined with the previous neck radiotherapy and neck lymph node dissection, it was considered that the blood pressure regulation was abnormal due to the damage of carotid sinus baroreceptor after radiotherapy for nasopharyngeal carcinoma and neck lymph node dissection, which was called ABF. At the same time, the patient was complicated with chronic hyponatremia. Combined with clinical and laboratory examination, the final consideration was caused by syndrome of in- appropriate antidiuretic hormone (SIADH). Baroreceptors controlled the secretion of heart rate, blood pressure and antidiuretic hormone through the mandatory "inhibition" signal. We speculate that the carotid sinus baroreceptor was damaged after neck radiotherapy and surgery, which leads to abnormal blood pressure regulation and nOH, while the function of inhibiting ADH secretion was weakened, resulting in higher ADH than normal level and mild hyponatremia. The goal of treating ABF patients was to reduce the frequency and amplitude of sudden changes in blood pressure and heart rate, and to alleviate the onset of symptomatic hypotension. At present, drug treatment is still controversial, and non-drug treatment may alleviate some patients' symptoms, but long-term effective treatment still needs further study. The incidence of ABF is not high, but it may lead to serious cardiovascular and cerebrovascular events, and the mechanism involved is extremely complicated, and there are few related studies. The reports of relevant medical records warn that patients undergoing neck radiotherapy or surgery should minimize the da-mage to the baroreceptor in the carotid sinus in order to reduce the adverse prognosis caused by complications.
Topics: Male; Humans; Baroreflex; Hypotension, Orthostatic; Hyponatremia; Hypertension; Blood Pressure; Head and Neck Neoplasms; Heart Rate; Vasopressins
PubMed: 38595258
DOI: 10.19723/j.issn.1671-167X.2024.02.025 -
Scientific Reports Apr 2024Cardiovascular risk increases during the aging process in women with atherosclerosis and exercise training is a strategy for management of cardiac risks in at-risk...
Cardiovascular risk increases during the aging process in women with atherosclerosis and exercise training is a strategy for management of cardiac risks in at-risk populations. Therefore, the aims of this study were to evaluate: (1) the influence of the aging process on cardiac function, hemodynamics, cardiovascular autonomic modulation, and baroreflex sensitivity in females with atherosclerosis at the onset of reproductive senescence; and (2) the impact of exercise training on age-related dysfunctions in this model. Eighteen Apolipoprotein-E knockout female mice were divided equally into young (Y), middle-aged (MA), and trained middle-aged (MAT). Echocardiographic exams were performed to verify cardiac morphology and function. Cannulation for direct recording of blood pressure and heart rate, and analysis of cardiovascular autonomic modulation, baroreflex sensitivity were performed. The MA had lower cardiac diastolic function (E'/A' ratio), and higher aortic thickness, heart rate and mean arterial pressure, lower heart rate variability and baroreflex sensitivity compared with Y. There were no differences between Y and MAT in these parameters. Positive correlation coefficients were found between aortic wall thickness with hemodynamics data. The aging process causes a series of deleterious effects such as hemodynamic overload and dysautonomia in female with atherosclerosis. Exercise training was effective in mitigating aged-related dysfunctions.
Topics: Humans; Middle Aged; Female; Mice; Animals; Aged; Heart; Hemodynamics; Cardiovascular System; Blood Pressure; Heart Rate; Autonomic Nervous System Diseases; Atherosclerosis
PubMed: 38570516
DOI: 10.1038/s41598-024-52883-x -
BioRxiv : the Preprint Server For... Mar 2024Thoracic epidural anesthesia (TEA) has been shown to reduce the burden of ventricular tachyarrhythmias (VT) in small case-series of patients with refractory VT and...
BACKGROUND
Thoracic epidural anesthesia (TEA) has been shown to reduce the burden of ventricular tachyarrhythmias (VT) in small case-series of patients with refractory VT and cardiomyopathy. However, its electrophysiological and autonomic effects in diseased hearts remain unclear and its use after myocardial infarction (MI) is limited by concerns for potential RV dysfunction.
METHODS
MI was created in Yorkshire pigs ( =22) by LAD occlusion. Six weeks post-MI, an epidural catheter was placed at the C7-T1 vertebral level for injection of 2% lidocaine. RV and LV hemodynamics were recorded using Millar pressure-conductance catheters, and ventricular activation-recovery intervals (ARIs), a surrogate of action potential durations, by a 56-electrode sock and 64-electrode basket catheter. Hemodynamics and ARIs, baroreflex sensitivity (BRS) and intrinsic cardiac neural activity, and ventricular effective refractory periods (ERP) and slope of restitution (S ) were assessed before and after TEA. VT/VF inducibility was assessed by programmed electrical stimulation.
RESULTS
TEA reduced inducibility of VT/VF by 70%. TEA did not affect RV-systolic pressure or contractility, although LV-systolic pressure and contractility decreased modestly. Global and regional ventricular ARIs increased, including in scar and border zone regions post-TEA. TEA reduced ARI dispersion specifically in border zone regions. Ventricular ERPs prolonged significantly at critical sites of arrhythmogenesis, and S was reduced. Interestingly, TEA significantly improved cardiac vagal function, as measured by both BRS and intrinsic cardiac neural activity.
CONCLUSION
TEA does not compromise RV function in infarcted hearts. Its anti-arrhythmic mechanisms are mediated by increases in ventricular ERP and ARIs, decreases in S , and reductions in border zone heterogeneity. TEA improves parasympathetic function, which may independently underlie some of its observed anti-arrhythmic mechanisms. This study provides novel insights into the anti-arrhythmic mechanisms of TEA, while highlighting its applicability to the clinical setting.
ABSTRACT ILLUSTRATION
Myocardial infarction is known to cause cardiac autonomic dysfunction characterized by sympathoexcitation coupled with reduced vagal tone. This pathological remodeling collectively predisposes to ventricular arrhythmia. Thoracic epidural anesthesia not only blocks central efferent sympathetic outflow, but by also blocking ascending projections of sympathetic afferents, relieving central inhibition of vagal function. These complementary autonomic effects of thoracic epidural anesthesia may thus restore autonomic balance, thereby improving ventricular electrical stability and suppressing arrhythmogenesis. DRG=dorsal root ganglion, SG=stellate ganglion.
PubMed: 38559001
DOI: 10.1101/2024.03.14.585127