Influence of sex and sedentary conditions on sympathetic burst characteristics in prepubertal, postpubertal, and young adult rats.

Recent evidence indicates that sex-based differences in cardiovascular disease (CVD) begin early in life, particularly when associated with risk factors such as a sedentary lifestyle. CVD is associated with elevated sympathetic nerve activity (SNA), quantified as increased SNA burst activity in humans. Whether burst characteristics are influenced by sex or sedentary conditions at younger ages is unknown. The purpose of our study is to compare SNA bursts in active and sedentary female and male rats at ages including prepuberty and young adulthood. We hypothesized that burst characteristics and blood pressure are higher under sedentary conditions and lower in female rats compared with males. We analyzed splanchnic SNA (SpSNA) recordings from Inactin-anesthetized male and female rats at 4-, 8-, and 16-wk of age. Physically active and sedentary rats were each housed in separate, environmentally controlled chambers where physically active rats had free access to an in-cage running wheel. Sympathetic bursts were obtained by rectifying and integrating the raw SpSNA signal. Burst frequency, burst height, and burst width were calculated using the Peak Parameters extension in LabChart. Our results showed that sedentary conditions produced a greater burst width in 8- and 16-wk-old rats compared with 4-wk-old rats in both males and females (P < 0.001 for both). Burst frequency and incidence were both higher in 16-wk-old males compared with 16-wk-old females (P < 0.001 for both). Our results suggest that there are sedentary lifestyle- and sex-related mechanisms that impact sympathetic regulation of blood pressure at ages that range from prepuberty into young adulthood.NEW & NOTEWORTHY The mechanisms of decreased incidence of cardiovascular disease (CVD) in reproductive-age women compared with age-matched men are unknown. The strong association between elevated sympathetic activity and CVD led us to characterize splanchnic sympathetic bursts in female and male rats. Prepubescent males and females exhibited narrower sympathetic bursts, whereas young adult males had higher resting burst frequency compared with age-matched females. Sex-based regulation of sympathetic activity suggests a need for sex-dependent therapeutic strategies to combat CVD.

A ganglionic intestinointestinal reflex activated by acute noxious challenge.

To investigate noxious stimulation-responsive neural circuits that could influence the gut, we recorded from intestinally directed (efferent) nerve filaments dissected from mesenteric nerves close to the small intestine in anesthetized rats. These exhibited baseline multiunit activity that was almost unaffected by vagotomy (VagX) and reduced only slightly by cutting the splanchnic nerves. The activity was halved by hexamethonium (Hex) treatment. When an adjacent gut segment received an intraluminal stimulus 2,4,6-trinitrobenzenesulfonate (TNBS) in 30% ethanol, mesenteric efferent nerve activity increased for more than 1 h. The increased activity was almost unaffected by bilateral vagotomy or splanchnic nerve section, indicating a lack of central nervous involvement, but it was 60% reduced by hexamethonium. Spike sorting discriminated efferent single and predominantly single-unit spike trains that responded to TNBS, were unaffected by splachnectomy but were silenced by hexamethonium. After noxious stimulation of one segment, the adjacent segment showed no evidence of suppression of gut motility or vasoconstriction. We conclude that luminal application of a noxious stimulus to the small intestine activates an entirely peripheral, intestinointestinal reflex pathway. This pathway involves enteric intestinofugal neurons that excite postganglionic sympathetic neurons via a nicotinic synapse. We suggest that the final sympathetic efferent neurons that respond to a tissue damaging stimulus are distinct from vasoconstrictor, secretomotor, and motility inhibiting neurons.NEW & NOTEWORTHY An intraluminal noxious chemical stimulus applied to one segment of small intestine increased mesenteric efferent nerve activity to an adjacent segment. This was identified as a peripheral ganglionic reflex that did not require vagal or spinal connections. Hexamethonium blocked most, but not all, ongoing and reflex mesenteric efferent activity. The prevertebral sympathetic efferent neurons that are activated likely affect inflammatory and immune functions of other gut segments.

Efficacy and Safety of Celiac Plexus Neurolysis Versus Splanchnic Nerve Neurolysis in the Management of Abdominal Cancer Pain: A Meta-analysis of 359 Patients.

BACKGROUND: Splanchnic nerve neurolysis (SNN) is commonly used as an alternative pain control technique to celiac plexus neurolysis (CPN) in patients with distortion of anatomy, but the analgesic effect and relative risks of the 2 procedures remain controversial in general condition. OBJECTIVES: The aim of this study was to evaluate the pain condition, safety, and symptom burden of SNN compared with CPN. STUDY DESIGN: A systematic review and meta-analysis of neurolysis therapy for intractable cancer-related abdominal pain. METHODS: A systematic search was performed for randomized controlled trials comparing SNN and CPN using the PubMed, Medline, Cochrane Library, Web of Science, Google Scholar, and China National Knowledge Infrastructure databases. Meta-analysis was performed using Stata Version 15.0. Outcomes included pain condition, opioid consumption, adverse effects, quality of life (QOL), and survival rate. Standardized mean difference (SMD) was calculated for continuous outcomes with its corresponding 95% CI. LIMITATIONS: Study limitations include challenges to make subgroup analysis by intervention measures and addressing inevitable heterogeneity. Larger studies are needed for survival rates and further insights. RESULTS: Seven studies involving 359 patients were included. No significant difference was found in pain condition at 2 weeks [SMD = 0.75, 95% CI (-0.25, 1.74), P > 0.05], 2 months [SMD = 1.10, 95% CI (-0.21, 2.40), P > 0.05] and 6 months [SMD = 0.53, 95% CI (-0.02, 1.08), P > 0.05] between SNN and CPN. Opioid consumption was comparable at 2 weeks [SMD = 0.57, 95% CI (-1.21, 2.34), P > 0.05] and one month [SMD = 0.37, 95% CI (-1.33, 2.07), P > 0.05]. However, SNN was associated with a statistically significant reduction in the opioid consumption at 2 months postoperatively [SMD = 0.99, 95% CI (0.68, 1.30), P < 0.05]. A systematic review was performed for adverse effects and QOL. CONCLUSIONS: Our evidence supports that the analgesic effect of SNN is equivalent to that of CPN, independent of changes in the anatomical structure of the abdominal nerve plexus. SNN requires less use of opioids at 2 months and does not show greater improvement in pain burden compared to CPN.

Dexmedetomidine in Fluoroscopic Guided Splanchnic Nerve Neurolysis for Pain Control: A Randomized, Controlled Trial.

BACKGROUND: Splanchnic nerve neurolysis (SNN) shows beneficial effects in reducing malignancy-associated refractory abdominal pain. Using adjuvants, such as dexmedetomidine to improve the pain was studied. OBJECTIVE: To detect any role of dexmedetomidine as an additive to local anesthetics with an alcohol injection in the chemical SNN process to improve pain in patients having upper-abdominal cancer. STUDY DESIGN: Double-blinded, prospective randomized study. SETTING: Department of Anesthesia and Intensive Care, faculty of medicine, Minia University,Egypt. METHODS: Forty patients with upper-abdominal malignancy-associated refractory abdominal pain underwent fluoroscopic guided SNN were divided into 2 groups. The SNN was performed by using 1.5 mL lidocaine 1%, dexmedetomidine 2 µg/kg, and then an injection of 4.5 mL of ethanol 96% on each side in group D and without dexmedetomidine in group C is done. Patients gave the score of abdominal pain expressed by the Visual Analog Scale (VAS), which measures the pain intensity. Scors were recorded prior to injection, during injection, after injection by 5 min, and after 2, 6, 12, 24, 72 hours, one week (W), 2 W, one month (M), and 2 M. Also, we recorded the amount of morphine required to relieve the residual pain after injection, the effect of procedure on quality of life (QOL), and any complication after injection. RESULTS: VAS scores showed a significant increase in group C in comparison to group D during injection, after injection by 5 min, 2, 6, 12, 24 hours, one and 2 months (P < 0.0001, 0.0001, 0.029, 0.031, 0.025, 0.040, 0.020, 0.015), respectively. The morphine requirement was significantly increased at one W, one M, and 2 M in group C in comparison to Group D (P < 0.044, 0.017, 0.033) with no significant change in the QOL observed between groups. LIMITATIONS: The limitations of this study were a relatively small sample size and short period of follow-up. CONCLUSIONS: This study revealed that using dexmedetomidine in the chemical SNN process improves the pain results from injection of alcohol and refractory cancer related pain with reduction in the consumption of morphine in patients with upper-abdominal malignancy.

Splanchnic Nerve Modulation Effects on Surrogate Measures of Venous Capacitance.

Background Splanchnic nerve modulation (SNM) is an emerging procedure to reduce cardiac filling pressures in heart failure. Although the main contributor to reduction in cardiac preload is thought to be increased venous capacitance in the splanchnic circulation, supporting evidence is limited. We examined changes in venous capacitance surrogates pre- and post-SNM. Methods and Results This is a prespecified analysis of a prospective, open-label, single-arm interventional study evaluating the effects of percutaneous SNM with ropivacaine in chronic heart failure with elevated filling pressures at rest and with exercise. Patients underwent cardiopulmonary exercise testing with invasive hemodynamic assessment pre- and post-SNM. Blood pressure changes with modified Valsalva maneuver and hemoconcentration, pre- and post-SNM were compared using a repeated measures model. Inferior vena cava diameter and collapsibility (>50% decrease in size with inspiration), and presence of bendopnea pre- and post-SNM were also compared. Fifteen patients undergoing SNM (age 58 years, 47% women, 93% with left ventricular ejection fraction ≤35%) were included. After SNM, changes in systolic blood pressure during Valsalva (peak-to-trough) were greater (41 versus 48 mm Hg, P=0.025). Exercise-induced hemoconcentration was unchanged (0.63 versus 0.43 g/dL, P=0.115). Inferior vena cava diameter was reduced (1.59 versus 1.30 cm, P=0.034) with higher collapsibility (33% versus 73%, P=0.014). Bendopnea was less (47% versus 13%, P=0.025). Conclusions SNM resulted in increased venous capacitance, associated decreased cardiac preload, and decreased bendopnea. Minimally invasive measures of venous capacitance could serve as markers of successful SNM. Long-term effects of SNM on venous capacitance warrant further investigation for heart failure management. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT03453151.

Acute Inhibition of Inflammation Mediated by Sympathetic Nerves: The Inflammatory Reflex.

In this review, we will try to convince the readers that the immune system is controlled by an endogenous neural reflex, termed inflammatory reflex, that inhibits the acute immune response during the course of a systemic immune challenge. We will analyse here the contribution of different sympathetic nerves as possible efferent arms of the inflammatory reflex. We will discuss the evidence that demonstrates that neither the splenic sympathetic nerves nor the hepatic sympathetic nerves are necessary for the endogenous neural reflex inhibition of inflammation. We will discuss the contribution of the adrenal glands to the reflex control of inflammation, noting that the neurally mediated release of catecholamines in the systemic circulation is responsible for the enhancement of the anti-inflammatory cytokine interleukin 10 (IL-10) but not of the inhibition of the pro-inflammatory cytokine tumour necrosis factor α (TNF). We will conclude by reviewing the evidence that demonstrates that the splanchnic anti-inflammatory pathway, composed by preganglionic and postganglionic sympathetic splanchnic fibres with different target organs, including the spleen and the adrenal glands, is the efferent arm of the inflammatory reflex. During the course of a systemic immune challenge, the splanchnic anti-inflammatory pathway is endogenously activated to inhibit the TNF and enhance the IL-10 response, independently, presumably acting on separate populations of leukocytes.

Percutaneous splanchnic nerve neurolysis analgesic efficacy and safety for cancer-related pain: a systematic review and meta-analysis.

PURPOSE: To perform a systematic review and meta-analysis of publications to evaluate the analgesic efficacy and safety of percutaneous splanchnic nerve neurolysis (SNN) for cancer-related pain. METHODS: We searched PubMed, Cochrane Library, and Ichushi-Web for English or Japanese articles published up to July 2022 and reporting patients who underwent percutaneous SNN for cancer-related pain. The outcome measures assessed in the systematic review and meta-analysis were the pain measurement scales and morphine equivalents daily dose (MEDD) before and after the intervention and the rate of complications. RESULTS: Pooled pain measurement scores at pre-intervention, 1-2 weeks, and at 1, 2, 3, and 6 months post-intervention were 6.65 (95% confidence interval [CI], 5.77-7.67, I2 = 97%), 2.79 (95% CI, 2.00-3.88, I2 = 88%), 2.82 (95% CI, 2.49-3.20, I2 = 55%), 2.86 (95% CI, 2.64-3.10, I2 = 0%), 2.99 (95% CI, 2.56-3.46, I2 = 82%), and 3.09 (95% CI, 1.44-6.65, I2 = 70%), respectively. Mean MEDD was described in 8 of the 11 included articles. In all 8 articles, MEDD decreased up to 3 months post-intervention. The pooled minor complication rates for diarrhea and hypotension were 28% (95% CI, 13-49%, I2 = 85%) and 31% (95% CI, 16-51%, I2 = 80%), respectively. The pooled major complication rate was 2% (95% CI, 1-2%, I2 = 0%). CONCLUSIONS: Analysis indicates that percutaneous SNN for cancer-related pain can be performed safely with sustained reduction of pain measurement scales while reducing the administration of opioids.

Synaptotagmin-7 facilitates acetylcholine release in splanchnic nerve-chromaffin cell synapses during nerve activity.

Disturbances that threaten homeostasis elicit activation of the sympathetic nervous system (SNS) and the adrenal medulla. The effectors discharge as a unit to drive global and immediate changes in whole-body physiology. Descending sympathetic information is conveyed to the adrenal medulla via preganglionic splanchnic fibers. These fibers pass into the gland and synapse onto chromaffin cells, which synthesize, store, and secrete catecholamines and vasoactive peptides. While the importance of the sympatho-adrenal branch of the autonomic nervous system has been appreciated for many decades, the mechanisms underlying transmission between presynaptic splanchnic neurons and postsynaptic chromaffin cells have remained obscure. In contrast to chromaffin cells, which have enjoyed sustained attention as a model system for exocytosis, even the Ca2+ sensors that are expressed within splanchnic terminals have not yet been identified. This study shows that a ubiquitous Ca2+-binding protein, synaptotagmin-7 (Syt7), is expressed within the fibers that innervate the adrenal medulla, and that its absence can alter synaptic transmission in the preganglionic terminals of chromaffin cells. The prevailing impact in synapses that lack Syt7 is a decrease in synaptic strength and neuronal short-term plasticity. Evoked excitatory postsynaptic currents (EPSCs) in Syt7 KO preganglionic terminals are smaller in amplitude than in wild-type synapses stimulated in an identical manner. Splanchnic inputs also display robust short-term presynaptic facilitation, which is compromised in the absence of Syt7. These data reveal, for the first time, a role for any synaptotagmin at the splanchnic-chromaffin cell synapse. They also suggest that Syt7 has actions at synaptic terminals that are conserved across central and peripheral branches of the nervous system.

Online Detection of Catecholamine Release from the Perfused Rat Adrenal Gland.

Retrogradely perfused adrenal glands have historically served for establishing many of our current knowledge on the stimulus-secretion coupling process. Although the use of intact adrenals has largely been switched to isolated chromaffin cells, adrenal glands are still a very valuable tool to characterize physiological and pharmacological questions. Even more, this is an excellent preparation for studying the splanchnic nerve/chromaffin cell interaction. In this chapter, we will provide the ways to (i) perform retrograde perfusion of isolated rat adrenals, (ii) the method to apply electrical splanchnic nerve stimulation, and (iii) the preparation of adrenals to conduct online electrochemical detection of catecholamine release.

Opioid withdrawal symptoms after neurolytic splanchnic nerve block in cancer patients.

PURPOSE: Few reports on opioid withdrawal (OW) due to opioid tapering in cancer patients have been published. The incidence of and risk factors for OW after neurolytic splanchnic nerve block (NSNB) are unknown. This study aimed to elucidate the incidence of and risk factors for OW among cancer patients who could have reduced opioid doses after NSNB. METHODS: This was a multicenter, retrospective, observational study. We reviewed the medical charts of patients who underwent NSNB for intractable cancer pain at four tertiary hospitals in Yokohama City from April 2005 to October 2020. We included patients whose opioid dose was reduced by > 5 mg/day (equivalent oral morphine dose) within 14 days after NSNB. We classified the patients into two groups according to the presence or absence of OW symptoms and compared them. RESULTS: Of the 50 patients who underwent NSNB, 24 were included in the study. OW was observed in five (20.8%) patients. Pain and opioid use duration were significantly longer in OW patients than in non-OW patients (median pain duration 689 vs. 195 days; P < 0.043 and median opioid use duration 486 vs. 136 days; P < 0.030). The opioid tapering dose was significantly larger in patients with OW than in those without OW (median opioid tapering dose 75 vs. 40 mg; P < 0.046). CONCLUSIONS: OW was observed in 20.8% of the patients in the study. A longer pain and opioid use duration and a larger opioid tapering dose may predispose patients to OW.

Navigation Guidance for Percutaneous Splanchnic Nerve Radiofrequency Neurolysis: Preliminary Results.

Background and Objectives: To describe preliminary results upon the application of the "Cube Navigation System" (CNS) for computed tomography (CT)-guided splanchnic nerve radiofrequency neurolysis. Materials and Methods: CT-guided splanchnic nerve neurolysis was performed in five patients; in all cases, neurolysis was performed under CT guidance using the CNS. The mean patient age was 71.6 years (range 54-81 years; male/female: 5/0). Technical success, parameters of the neurolysis session and complications were evaluated. Technical success was defined as a needle position on the defined target. Session parameters included procedure time and number of scans. The CIRSE reporting system was used for complications' classification and grading. Results: Technical success was obtained in all cases; in 1/5 patients, a slight correction in needle orientation was necessary. Mean procedure time was 12.4 min (range 8-19 min); an average of four CT scans was recorded in the five neurolysis sessions. There were no complications or material failures reported in the present study. Conclusions: Preliminary results of the present study show that computed tomography (CT)-guided splanchnic nerve radiofrequency neurolysis using the CNS is an accurate and time-efficient percutaneous procedure. More prospective and comparative studies with larger patient samples are necessary for verification of this system as well as for drawing broader conclusions.

Transvenous Right Greater Splanchnic Nerve Ablation in Heart Failure and Preserved Ejection Fraction: First-in-Human Study.

BACKGROUND: Ablation of the right-sided greater splanchnic nerve (GSN) can reduce excessive splanchnic vasoconstriction, potentially improving the handling of volume shifts in patients with heart failure with preserved ejection fraction (HFpEF). OBJECTIVES: The purpose of this study was to assess a novel catheter procedure of right-sided GSN ablation to treat HFpEF: splanchnic ablation for volume management. METHODS: This trial included 11 HFpEF patients (8 women, age 70 ± 8 years) with New York Heart Association functional class II or III symptoms, ejection fraction ≥50%, and elevated pulmonary capillary wedge pressure at rest or with exercise. After splanchnic ablation for volume management, follow-up at 1, 3, 6, and 12 months included 6-minute walk test, Kansas City Cardiomyopathy Questionnaire (KCCQ), and echocardiography. RESULTS: There were no device-related adverse cardiac events or clinical sequelae following right GSN ablation through 12 months. Patients experienced clinical improvements by 1 month that were sustained through 12 months. KCCQ score improved from baseline median 48 (IQR: 35-52) to 65 (IQR: 58-77) at 1 month and 80 (IQR: 77-88) at 12 months (P < 0.05). The 6-minute walk test distance increased from baseline 292 ± 82 m to 341 ± 88 m at 1 month and 359 ± 75 m at 12 months (P < 0.05). The NT-proBNP decreased from a baseline mean of 1,292 ± 1,186 pg/mL to 1,202 ± 797 pg/mL (P = 0.585) at 1 month, to 472 ± 226 pg/mL (P = 0.028) at 6 months, and to 379 ± 165 pg/mL (P = 0.039) at 12 months. CONCLUSIONS: In this open-label, single-arm feasibility study, right-sided GSN ablation was safe and improved mostly subjective clinical metrics in patients with HFpEF over 12 months. (Endovascular GSN Ablation in Subjects With HFpEF; NCT04287946).

Divergent splanchnic sympathetic efferent nerve pathways regulate interleukin-10 and tumour necrosis factor-α responses to endotoxaemia.

The efferent branches of the splanchnic sympathetic nerves that enhance interleukin-10 (IL-10) and suppress tumour necrosis factor-α (TNF) levels in the reflex response to systemic immune challenge were investigated in anaesthetized, ventilated rats. Plasma levels of TNF and IL-10 were measured 90 min after intravenous lipopolysaccharide (LPS, 60 µg/kg). Splanchnic nerve section, ganglionic blockade with pentolinium tartrate or ß2 adrenoreceptor antagonism with ICI 118551 all blocked IL-10 responses. Restoring plasma adrenaline after splanchnic denervation rescued IL-10 responses. TNF responses were disinhibited by splanchnic denervation or pentolinium treatment, but not by ICI 118551. Splanchnic nerve branches were cut individually or in combination in vagotomized rats, ruling out any vagal influence on results. Distal splanchnic denervation, sparing the adrenal nerves, disinhibited TNF but did not reduce IL-10 responses. Selective adrenal denervation depressed IL-10 but did not disinhibit TNF responses. Selective denervation of either spleen or liver did not affect IL-10 or TNF responses, but combined splenic and adrenal denervation did so. Finally, combined section of the cervical and lumbar sympathetic nerves did not affect cytokine responses to LPS. Together, these results show that the endogenous anti-inflammatory reflex is mediated by sympathetic efferent fibres that run in the splanchnic, but not other sympathetic nerves, nor the vagus. Within the splanchnic nerves, divergent pathways control these two cytokine responses: neurally driven adrenaline, acting via ß2 adrenoreceptors, regulates IL-10, while TNF is restrained by sympathetic nerves to abdominal organs including the spleen, where non-ß2 adrenoreceptor mechanisms are dominant. KEY POINTS: An endogenous neural reflex, mediated by the splanchnic, but not other sympathetic nerves, moderates the cytokine response to systemic inflammatory challenge. This reflex suppresses the pro-inflammatory cytokine tumour necrosis factor-α (TNF), while enhancing levels of the anti-inflammatory cytokine interleukin-10 (IL-10). The reflex enhancement of IL-10 depends on the splanchnic nerve supply to the adrenal gland and on ß2 adrenoreceptors, consistent with mediation by circulating adrenaline. After splanchnic nerve section it can be rescued by restoring circulating adrenaline. The reflex suppression of TNF depends on splanchnic nerve branches that innervate abdominal tissues including, but not restricted to, spleen: it is not blocked by adrenal denervation or ß2 adrenoreceptor antagonism. Distinct sympathetic efferent pathways are thus responsible for pro- and anti-inflammatory cytokine components of the reflex regulating inflammation.

Minimally invasive management for multifocal pelvic retroperitoneal malignant paraganglioma: a neuropelveological approach.

BACKGROUND: Pheochromocytoma and Paraganglioma (PGL) are rare neuroendocrine tumors, with an estimated incidence of about 0.6 cases per 100.000 person/year. Overall, 3-8% of them are malignant. These tumors are characterized by a classic triad of symptoms (headaches, palpitations, profuse sweating) due to hypersecretion of catecholamines. Despite several advantages of minimally invasive surgery (MIS) for PGL debulking, the surgical approach is not standardized yet. In this scenario, we aimed to report a case of a multiple recurrent PGL with metastatic retroperitoneal localization involving the pelvic sidewall, excised with MIS. CASE PRESENTATION: We performed complete laparoscopic-assisted neuronavigation (LANN technique) with isolation of the sacral routes and the sciatic nerve to obtain complete exposure of the main anatomic landmarks. Robotic surgery was used to perform neurolysis of sacral plexus, and partial resection of left splanchnic nerves was needed. After the resection of the first mass, extensive neurolysis of all sacral routes, obturator nerve, pudendal nerve till the entrance of the pudendal (Alcock) canal, and sciatic nerve was performed. Finally, the mass was identified after trans gluteal incision and dissection of the maximum gluteal muscle, and a partial resection of the superior gluteal nerve and slicing of the sciatic nerve were needed to obtain a radical excision of the mass. Then neurorrhaphy of the sectioned nerve fibers of the superior gluteal nerve was performed, and nerve protection was obtained using a collagen nerve wrap. After 18 months of follow-up, the patient is free of disease at the MRI imaging and 123I-metaiodobenzylguanidine scintigraphy. CONCLUSIONS: Minimally invasive gynecological surgery with neuropelveological approach could be considered as a feasible option in case of multifocal pelvic retroperitoneal malignant paraganglioma of the pelvic side wall.

Basal and Stress-Induced Network Activity in the Adrenal Medulla In Vivo.

The adrenal medulla plays a critical role in mammalian homeostasis and the stress response. It is populated by clustered chromaffin cells that secrete epinephrine or norepinephrine along with peptides into the bloodstream affecting distant target organs. Despite been heavily studied, the central control of adrenal medulla and in-situ spatiotemporal responsiveness remains poorly understood. For this work, we continuously monitored the electrical activity of individual adrenomedullary chromaffin cells in the living anesthetized rat using multielectrode arrays. We measured the chromaffin cell activity under basal and physiological stress conditions and characterized the functional micro-architecture of the adrenal medulla. Under basal conditions, chromaffin cells fired action potentials with frequencies between ~0.2 and 4 Hz. Activity was almost completely driven by sympathetic inputs coming through the splanchnic nerve. Chromaffin cells were organized into independent local networks in which cells fired in a specific order, with latencies from hundreds of microseconds to a few milliseconds. Electrical stimulation of the splanchnic nerve evoked almost exactly the same spatiotemporal firing patterns that occurred spontaneously. Hypoglycemic stress, induced by insulin administration resulted in increased activity of a subset of the chromaffin cells. In contrast, respiratory arrest induced by lethal anesthesia resulted in an increase in the activity of virtually all chromaffin cells before cessation of all activity. These results suggest a stressor-specific activation of adrenomedullary chromaffin cell networks and revealed a surprisingly complex electrical organization that likely reflects the dynamic nature of the adrenal medulla's neuroendocrine output during basal conditions and during different types of physiological stress.

Endovascular ablation of the right greater splanchnic nerve in heart failure with preserved ejection fraction: early results of the REBALANCE-HF trial roll-in cohort.

AIMS: In heart failure (HF) with preserved ejection fraction (HFpEF), excessive redistribution of blood volume into the central circulation leads to elevations of intracardiac pressures with exercise limitations. Splanchnic ablation for volume management (SAVM) has been proposed as a therapeutic intervention. Here we present preliminary safety and efficacy data from the initial roll-in cohort of the REBALANCE-HF trial. METHODS AND RESULTS: The open-label (roll-in) arm of REBALANCE-HF will enrol up to 30 patients, followed by the randomized, sham-controlled portion of the trial (up to 80 additional patients). Patients with HF, left ventricular ejection fraction (LVEF) ≥50%, and invasive peak exercise pulmonary capillary wedge pressure (PCWP) ≥25 mmHg underwent SAVM. Baseline and follow-up assessments included resting and exercise PCWP, New York Heart Association (NYHA) class, Kansas City Cardiomyopathy Questionnaire (KCCQ), 6-min walk test, and N-terminal pro-B-type natriuretic peptide (NT-proBNP). Efficacy and safety were assessed at 1 and 3 months. Here we report on the first 18 patients with HFpEF that have been enrolled into the roll-in, open-label arm of the study across nine centres; 14 (78%) female; 16 (89%) in NYHA class III; and median (interquartile range) age 75.2 (68.4-81) years, LVEF 61.0 (56.0-63.2)%, and average (standard deviation) 20 W exercise PCWP 36.4 (±8.6) mmHg. All 18 patients were successfully treated. Three non-serious moderate device/procedure-related adverse events were reported. At 1-month, the mean PCWP at 20 W exercise decreased from 36.4 (±8.6) to 28.9 (±7.8) mmHg (p < 0.01), NYHA class improved by at least one class in 33% of patients (p = 0.02) and KCCQ score improved by 22.1 points (95% confidence interval 9.4-34.2) (p < 0.01). CONCLUSION: The preliminary open-label results from the multicentre REBALANCE-HF roll-in cohort support the safety and efficacy of SAVM in HFpEF. The findings require confirmation in the ongoing randomized, sham-controlled portion of the trial.

Targeting Preload in Heart Failure: Splanchnic Nerve Blockade and Beyond.

Preload augmentation represents a critical mechanism for the cardiovascular system to increase effective circulating blood volume to increase cardiac filling pressures and, subsequently, for the heart to increase cardiac output. The splanchnic vascular compartment is the primary source of vascular capacity and thus the primary target for preload recruitment in humans. Under normal conditions, sympathetic stimulation of these primary venous vessels promotes the shift of blood from the splanchnic to the thoracic compartment and elevates preload and cardiac output. However, in heart failure, since filling pressures may be elevated at rest due to decreased venous capacitance, incremental recruitment of preload to enhance cardiac output may exacerbate congestion and limit exercise capacity. Accordingly, recent attention has focused on therapies designed to regulate splanchnic vascular redistribution to improve cardiac filling pressures and patient-centered outcomes such as quality of life and exercise capacity in patients with heart failure. In this review, we discuss the relevance of splanchnic circulation as a venous reservoir, the contribution of stressed blood volume to heart failure pathogenesis, and the implications for pharmacological therapeutic interventions to prevent heart failure decompensation. Further, we review emerging device-based approaches for cardiac preload reduction such as partial/complete occlusion of the superior vena cava or the inferior vena cava.