Effects of bilateral renal denervation on open-loop baroreflex function and urine excretion in spontaneously hypertensive rats.

Bilateral renal denervation (RDN) decreases arterial pressure (AP) or delays the development of hypertension in spontaneously hypertensive rats (SHR), but whether bilateral RDN significantly modifies urine output function during baroreflex-mediated acute AP changes remains unknown. We quantified the relationship between AP and normalized urine flow (nUF) in SHR that underwent bilateral RDN (n = 9) and compared the results with those in sham-operated SHR (n = 9). Moreover, we examined the acute effect of an angiotensin II type 1 receptor blocker telmisartan (2.5 mg/kg) on the AP-nUF relationship. Bilateral RDN significantly decreased AP by narrowing the response range of the total arc of the carotid sinus baroreflex. The slopes of nUF versus the mean AP (in µL·min-1·kg-1·mmHg-1) in the sham and RDN groups under baseline conditions were 0.076 ± 0.045 and 0.188 ± 0.039, respectively; and those after telmisartan administration were 0.285 ± 0.034 and 0.416 ± 0.078, respectively. The effect of RDN on the nUF slope was marginally significant (P = 0.059), which may have improved the controllability of urine output in the RDN group. The effect of telmisartan on the nUF slope was significant (P < 0.001) in the sham and RDN groups, signifying the contribution of circulating or locally produced angiotensin II to determining urine output function regardless of ongoing renal sympathetic nerve activity.

Severe hypotension requiring resuscitation in tumour-related carotid sinus syndrome: a case report.

Background: An uncommon cause of reflex syncope is carotid sinus syndrome (CSS). In rare cases, this can be caused by compression of the carotid sinus by a progressive or invasive tumour. Case summary: A 57-year-old female was presented at the emergency department with recurrent syncope in the morning. After initial observation, no heart rhythm abnormalities or syncope were observed. The day after discharge, she was presented again with a syncope. Hypotension and bradycardia were observed this time. Furthermore, a mass in the neck area was found near the carotid artery. She was admitted to the cardiology department with suspected carotid sinus syndrome for telemetric observation. Diagnostics by biopsy and PET-CT showed a metastasized squamous cell carcinoma of the tongue. Initial treatment of dexamethasone was started after which the recurrence of the syncope decreased. However, during admission, an in-hospital cardiac arrest occurred due to persistent vagal stimulation. As a result, the patient was started on neoadjuvant chemotherapy and midodrine, after which she experienced multiple complications and died. Discussion: To the best of our knowledge, this is the first case report that shows an IHCA due to severe hypotension related to a carotid sinus syndrome.

Precranial artery calcification burden: a potential indicator of the clinical outcome of reperfusion in patients with acute large artery occlusion.

OBJECTIVE: With mechanical thrombectomy (MT), we investigated the prognostic importance of aortic arch calcification (AoAC) and carotid sinus calcification (CaSC) for symptomatic intracerebral hemorrhage (sICH) and poor outcome in acute large artery occlusion (LAO). METHODS: In this retrospective observational study, we calculated pre-cranial artery calcification burden (PACB) scores (burden score of AoAC and CaSC) using the AoAC grading scale score plus Woodcock visual score. The outcome measure was sICH per the European Cooperative Acute Stroke Study III definition. A 3-month modified Rankin scale score 3-6 was designated as poor outcome. RESULTS: Compared with patients who had PACB <3, those with PACB ≥3 showed substantially higher risks of sICH (odds ratio [OR] = 2.567, 95% confidence interval [CI] = 1.187-5.550) and poor outcome (OR = 4.777, 95% CI = 1.659-13.756). According to receiver operating characteristic (ROC) curves, adding PACB to the regression model enhanced the predictive value for poor outcome (area under the ROC curve [AUC]: 0.718 vs. 0.519, Z = 2.340) and in patients receiving MT (AUC: 0.714 vs. 0.584, Z = 2.021), independently. CONCLUSIONS: Factors related to PACB were consistent with common risk factors of systemic atherosclerosis. Low PACB scores indicated better prognosis. In patients with LAO following MT, PACB was useful in predicting sICH and poor clinical outcome.

Images in Anesthesiology: Carotid Sinus Reflex From Neck Mass and Opioids.

Surgery on head and neck masses presents unique challenges to overcome, especially in relation to preoperative anesthesia induction. Tumor proximity to the carotid sinus can result in extreme hemodynamic depression, by way of compression or direct invasion of the node. Neck hyperextension required for endotracheal intubation can worsen the underlying compression. Additionally, many anesthetic agents have sympatholytic properties that can exacerbate this imbalance further toward the parasympathetic response. We present a case of a patient with non-Hodgkin lymphoma whose tumor compression of the carotid sinus precipitated an exaggerated vagal reflex response following fentanyl administration.

Carotid Sinus Syndrome With Convulsive Syncope in a Patient With Head and Neck Cancer.

This case report provides a comprehensive overview of a unique case of a 64-year-old male patient with head and neck (H&N) cancer who initially presented with compressive convulsive syncope, an initial manifestation of carotid sinus syndrome (CSS). CSS is an autonomic nervous system disease that often manifests as hypotension, dizziness, cerebral ischemia, or syncope, usually in elderly patients. In this case, the patient's laryngeal cancer led to lymphedema and encasement of the bilateral carotid arteries, inducing CSS and resulting in recurrent episodes of hypotension and bradycardia. These symptoms were managed through the administration of atropine and transcutaneous pacemaker placement, suggesting a probable mixed type of CSS. The patient was discharged on long-term theophylline treatment for symptomatic control of bradycardia episodes. Despite the promising outcomes of CSS cases treated with pacemakers, the efficacy is not universal and limitations may arise, particularly in H&N cancer patients. Therefore, the patient was managed with theophylline rather than a pacemaker due to its non-invasiveness and effectiveness in temporarily managing CSS. Although rare, CSS should be considered in patients experiencing convulsive syncope alongside H&N malignancies. As the evidence and consensus regarding CSS treatment in H&N cancer patients are scarce, additional research is necessary to evaluate and compare available options. This abstract concludes by emphasizing the need for further research and case reports to establish a consensus on the optimal management approach for patients affected by CSS due to compression from H&N cancers.

Three-Dimensional Ultrastructure of Flower-Spray Nerve Endings in the Rat Carotid Sinus.

The flower-spray nerve endings are afferent nerve terminals in the carotid sinus that arise from carotid sinus nerve of glossopharyngeal nerve. However, the three-dimensional ultrastructural characteristics of flower-spray nerve endings and spatial relationships between the terminal parts and other cellular elements have not been fully understood. To elucidate their detailed relationship, backscattered electron imaging of serial sections was performed with a scanning electron microscope to produce a three-dimensional reconstruction of the flower-spray endings. The terminal parts of flower-spray endings were distributed horizontally approximately 5 µm outside the external elastic membrane in the tunica adventitia of the internal carotid artery. The three-dimensional reconstruction showed that the terminal parts of flower-spray endings were flat with irregular contours and were partially covered by the thin cytoplasmic processes of Schwann cells. The complex consisting of the nerve terminals and associated Schwann cells was surrounded by a multilayered basement membrane. The terminal parts of the endings were also surrounded by fibroblasts with elastic fibers and collagen fibrils. Secretory vesicles without an electron-dense core were observed in the terminal parts of the endings. The accumulation of vesicles just below the axonal membrane was observed in terminal parts not covered by Schwann cell cytoplasmic processes on both the luminal and basal sides. Swollen mitochondria, concentric membranous structures, and glycogen granule-like electron-dense materials were often noted in some of the terminal parts of the endings and the parent axon. Collectively, the present results suggest that flower-spray endings are baroreceptors because their morphology was similar to other mechanoreceptors. Furthermore, flower-spray endings may be affected by glutamate secreted in an autocrine manner.

Bioelectronic modulation of carotid sinus nerve to treat type 2 diabetes: current knowledge and future perspectives.

Bioelectronic medicine are an emerging class of treatments aiming to modulate body nervous activity to correct pathological conditions and restore health. Recently, it was shown that the high frequency electrical neuromodulation of the carotid sinus nerve (CSN), a small branch of the glossopharyngeal nerve that connects the carotid body (CB) to the brain, restores metabolic function in type 2 diabetes (T2D) animal models highlighting its potential as a new therapeutic modality to treat metabolic diseases in humans. In this manuscript, we review the current knowledge supporting the use of neuromodulation of the CSN to treat T2D and discuss the future perspectives for its clinical application. Firstly, we review in a concise manner the role of CB chemoreceptors and of CSN in the pathogenesis of metabolic diseases. Secondly, we describe the findings supporting the potential therapeutic use of the neuromodulation of CSN to treat T2D, as well as the feasibility and reversibility of this approach. A third section is devoted to point up the advances in the neural decoding of CSN activity, in particular in metabolic disease states, that will allow the development of closed-loop approaches to deliver personalized and adjustable treatments with minimal side effects. And finally, we discuss the findings supporting the assessment of CB activity in metabolic disease patients to screen the individuals that will benefit therapeutically from this bioelectronic approach in the future.

Hormonal Control of Blood Viscosity.

The hemodynamic milieu differs throughout the vascular tree because of varying vascular geometry and blood velocities. Accordingly, the risk of turbulence, which is dictated by the Reynolds and Dean numbers, also varies. Relatively high blood viscosity is needed to prevent turbulence in the left ventricle and aorta, where high-velocity blood changes direction several times. Low blood viscosity is needed in the capillaries, where erythrocytes pass through vessels with a diameter smaller than their own. In addition, higher blood viscosity is necessary when the cardiac output and peak blood velocity increase as a part of a sympathetic response or anemia, which occurs following significant hemorrhage. Blood viscosity, as reflected in systemic vascular resistance and vascular wall shear stress, is sensed, respectively, by cardiomyocyte stretching in the left ventricle and mechanoreceptors for wall shear stress in the carotid sinus. By controlling blood volume and red blood cell mass, the renin-aldosterone-angiotensin system and the systemic vascular resistance response control the hematocrit, the strongest intrinsic determinant of blood viscosity. These responses provide gross control of blood viscosity. Fine-tuning of blood viscosity in transient conditions is provided by hormonal control of erythrocyte deformability. The short half-life of some of these hormones limits their activity to specific vascular beds. Hormones that modulate blood viscosity include erythropoietin, angiotensin II, brain natriuretic factor, epinephrine, prostacyclin E2, antidiuretic hormone, and nitric oxide.

A Case of Carotid Sinus Reflex Caused by Manual Aspiration Thrombectomy Using a Balloon Guide Catheter.

When starting a mechanical thrombectomy, manual aspiration with balloon guide catheters inserted into the internal carotid artery (ICA) is an efficient method for thrombus aspiration. However, no complications associated with this procedure have been reported. This study describes the case of a 76-year-old man who presented to our hospital with total aphasia and complete right-sided paralysis due to chronic atrial fibrillation and left occlusion of the ICA. When the balloon guide catheter was inserted and inflated at the origin of the left ICA, the patient's systolic blood pressure suddenly decreased from 114 mm Hg to 44 mm Hg. This sudden hypotension may have been caused by the carotid sinus reflex. Hypotension improved following balloon deflation. The procedure was continued, resulting in complete recanalization of the left ICA. The patient died from acute exacerbation of interstitial pneumonia. Although this complication is rare, similar phenomena have been recognized in carotid artery stenting and the use of flow-diverting devices. To the best of our knowledge, this is the first report of a case wherein the carotid sinus reflex was induced by manual aspiration using a balloon guide catheter placed in the ICA. Clinicians should recognize the importance of ensuring that the proximal end of the balloon crosses the carotid sinus when dilating and occluding the ICA with a balloon to avoid the carotid sinus reflex.

Carotid Web as a Source of Thromboembolism in a Young African American Female.

Background: Carotid webs are nonatherosclerotic fibrous bands that may alter hemodynamic flow and increase the risk of platelet aggregation, leading to thromboembolism in young, otherwise healthy individuals. Although rare, carotid webs are important causes of thromboembolic strokes and are often overlooked in the routine workup for a stroke. Treating physicians and radiologists must recognize and properly manage patients who present with carotid webs to prevent recurrent thromboembolism. Case Report: A healthy 30-year-old female presented with slurred speech and unilateral left upper and lower extremity numbness. Imaging modalities showed an acute infarction of the right middle cerebral artery and bilateral carotid webs. The patient was managed operatively with a right carotid endarterectomy and discharged on day 3 of admission on a regimen of ticagrelor, amlodipine, and aspirin. The patient was asymptomatic at 1-year follow-up. Conclusion: Our case highlights the clinical relevance of considering carotid web as a potential etiology for ischemic stroke in young, otherwise healthy patients and emphasizes the importance of timely diagnosis and appropriate management to prevent recurrent cerebrovascular events.

Carotid Sinus Tumor-Induced Positional Bradycardia and Hypotension After Extubation: A Case Report.

Regional progression of head and neck malignancies can lead to carotid sinus tumors, causing hemodynamic instability and carotid sinus syndrome (CSS). A 60-year-old male with tonsillar squamous cell carcinoma developed profound positional bradycardia and hypotension immediately after extubation following dental extraction. The patient developed recurrent episodes of positional bradycardia and hypotension, leading to eventual pacemaker placement. Further workup revealed a large mass in the left neck and necrotic cervical lymphadenopathy, indicating CSS from malignancy compression. This case highlights the need for consideration of CSS in patients with known head and neck malignancy, particularly when postural hypotension and bradycardia are present.

Syncope in older adults: challenges, approach and treatment.

Syncope can have devastating consequences, resulting in injuries, accidents or even death. In our ageing society, the subsequent healthcare usage, such as emergency room presentations, surgeries and hospital admissions, forms a significant and growing socioeconomic burden. Causes of syncope in the older adult include orthostatic hypotension, carotid sinus syndrome, vasovagal syncope, structural cardiac abnormalities, cardiac arrhythmias and conduction abnormalities. As stated in the recently published World Falls Guidelines, syncope in older adults often presents as falls, which is either due to amnesia for loss of consciousness, or pre-syncope leading to a fall, especially in those prone to falls with several other risk-factors for falls present. This difference in presentation can hinder the recognition of syncope. In patients with unexplained falls, or in whom the history comprises red flags for potential syncope, special attention to (pre)syncope is therefore warranted. When syncope is mistaken for other causes of a transient loss of consciousness, such as epileptic seizures, or when syncope presents as falls, patients are often referred to multiple specialists, which may in turn lead to excessive and unnecessary diagnostic testing and costs. Specialist services that are able to provide a comprehensive assessment can improve diagnostic yield and minimise diagnostic testing, thus improving patient satisfaction. Comprehensive assessment also leads to reduced length of hospital stay. Increasingly, geriatricians are involved in the assessment of syncope in the older patient, especially given the overlap with falls. Therefore, awareness of causes of syncope, as well as state-of-the-art assessment and treatment, is of great importance.

The effect of carotid sinus neurectomy for carotid restenosis: a study protocol for a double-blinded and randomized controlled trial.

BACKGROUND: Patients undergoing carotid endarterectomy (CEA) have a high restenosis rate, which increases the risk of stroke, and there is still a lack of effective treatment for restenosis. The cause of stenosis is related to local inflammatory reactions. Some basic studies have shown that the inflammatory response causing arterial stenosis is closely related to the nerve axons distributed in its outer membrane, and that removal of the nerve is effective in reducing the inflammatory response to prevent arterial stenosis. Therefore, we propose to design a randomized controlled trial to study whether disconnecting the carotid sinus nerve during a CEA operation can reduce carotid arterial restenosis. METHOD/DESIGN: This study is a randomized, double-blind, single-center study. We will recruit 276 patients, who will be randomly divided into the experimental group and the control group. Based on the standard CEA operation, the operator will search for the carotid sinus nerve on the surface of the internal carotid artery and will entirely transect it in the experimental group. Both groups will be guided with the same postoperative treatment and will be followed up every 3 months for 3 years after the operation. The main indices observed will be the carotid restenosis rate, incidence and nature of carotid plaque, and carotid blood flow velocity. Other indices will be arrhythmia, blood pressure variability, and biomarkers of atherosclerosis, such as blood lipids, hypersensitive C-reactive protein (hs-CRP), homocysteine, and total bilirubin. DISCUSSION: It is expected that carotid sinus nerve transection will significantly reduce the occurrence of restenosis after CEA, decrease the incidence of ischemic stroke, and realize the effective primary prevention of stroke. TRIAL REGISTRATION: ChiCTR2300073652. Registered on July 18, 2023.

Cardiovascular Disorders and Falls Among Older Adults: A Systematic Review and Meta-Analysis.

BACKGROUND: Falls are a common cause of injury, hospitalization, functional decline, and residential care admission among older adults. Cardiovascular disorders are recognized risk factors for falls. This systematic review assesses the association between cardiovascular disorders and falls in older adults. METHODS: Systematic searches were conducted on MEDLINE and Embase, encompassing all literature published prior to December 31, 2022. Included studies addressed persons aged 50 years and older, and assessed the association between cardiovascular disorders and falls or the efficacy of cardiovascular-based interventions to reduce falls. Two reviewers independently extracted data and assessed study quality utilizing a modified Newcastle-Ottawa scale for observational studies, and the Cochrane Risk of Bias 2 tool for interventional studies. A systematic narrative analysis of all cardiovascular outcomes, and meta-analyses of unadjusted odds ratios (ORs) were performed. RESULTS: One hundred and eighty-four studies were included: 181 observational and 3 interventional. Several cardiovascular disorders, including stroke, coronary artery disease, valvular heart disease, arterial stiffness, arrhythmia, orthostatic hypotension, and carotid sinus hypersensitivity, were consistently associated with falls. In meta-analysis of unadjusted ORs, the largest positive pooled associations with falls during a 12-month reporting interval were for stroke (OR: 1.90, 95% confidence interval [CI]: 1.70-2.11), peripheral arterial disease (OR: 1.82, 95% CI: 1.12-2.95), atrial fibrillation (OR: 1.52, 95% CI: 1.27-1.82), and orthostatic hypotension (OR: 1.39, 95% CI: 1.18-1.64). CONCLUSIONS: Several cardiovascular disorders are associated with falls. These results suggest the need to incorporate cardiovascular assessments for patients with falls. This review informed the cardiovascular recommendations in the new World Guidelines for falls in older adults.Clinical Trials Registration Number: CRD42021272245.

Supraventricular Tachycardia Associated With Repeat Cesarean Section Under Spinal Anesthesia.

Supraventricular tachycardia (SVT) is the most common tachyarrhythmia of pregnancy. Catecholamine surges, the use of vasoactive agents during delivery, and increased cardiac output during pregnancy are the most common contributing factors to developing SVT. SVT is usually benign in presentation but can lead to more serious arrhythmias in patients with a history of mitral stenosis secondary to rheumatic heart disease. When an SVT is detected, organic heart causes should be ruled out first. Symptoms of SVT include shortness of breath, palpitations, syncope, sweating, chest pain, and dizziness. In patients who are refractory to pharmacologic management and hemodynamically unstable, electrical cardioversion has proven to be efficacious and safe in all trimesters. The initial treatment for hemodynamically stable patients is to attempt vagal maneuvers, such as carotid sinus massage or Valsalva maneuver. If the SVT does not convert to normal sinus rhythm, treatment with adenosine or beta-blockers may be initiated. Treatment with atenolol and verapamil should be avoided due to their teratogenic effects.

Electrical carotid sinus nerve stimulation attenuates experimental colitis induced by acetic acid in rats.

AIMS: The carotid bodies are sensors that detect physiological signals and convey them to the central nervous system, where the stimuli are processed inducing reflexes through efferent pathways. Recent studies have demonstrated that electrical stimulation of the carotid sinus nerve (CSN) triggers the anti-inflammatory reflex under different conditions. However, whether this electrical stimulation attenuates colitis was never examined. This study aimed to evaluate if the electrical CSN stimulation attenuates the experimental colitis induced by intrarectal administration of acetic acid in rats. METHODS: Electrodes were implanted around the CSN to stimulate the CSN, and a catheter was inserted into the left femoral artery to record the arterial pressure. The observation of hypotensive responses confirmed the effectiveness of the electrical CNS stimulation. This maneuver was followed by a 4 % acetic acid or saline administered intrarectally. After 24 h, colons were segmented into distal and proximal parts for macroscopy, histological and biochemical assessment. KEY FINDINGS: As expected, the electrical CSN stimulation was effective in decreasing arterial pressure in saline and colitis rats. Moreover, electrical CSN stimulation effectively reduced colonic tissue lesions, colitis scores, and histopathologic parameters associated with colitis. In addition, the CSN stimulation also reduced the colonic mucosa pro-inflammatory cytokine interleukin-1 beta, and increased the anti-inflammatory interleukin-10, in rats submitted to colitis. SIGNIFICANCE: These findings indicated that electrical CSN stimulation breaks the vicious cycle of local colon inflammation in colitis, which might contribute to its better outcome.

General Morphology of the Mammalian Carotid Body.

The carotid body (CB) is the main peripheral arterial chemoreceptor that registers the levels of pO2, pCO2 and pH in the blood and responds to their changes by regulating breathing. It is strategically located in the bifurcation of each common carotid artery. The organ consists of "glomera" composed of two cell types, glomus and sustentacular cells, interspersed by blood vessels and nerve bundles and separated by connective tissue. The neuron-like glomus or type I cells are considered as the chemosensory cells of the CB. They contain numerous cytoplasmic organelles and dense-cored vesicles that store and release neurotransmitters. They also form both conventional chemical and electrical synapses between each other and are contacted by peripheral nerve endings of petrosal ganglion neurons. The glomus cells are dually innervated by both sensory nerve fibers through the carotid sinus nerve and autonomic fibers of sympathetic origin via the ganglioglomerular nerve. The parasympathetic efferent innervation is relayed by vasomotor fibers of ganglion cells located around or inside the CB. The glial-like sustentacular or type II cells are regarded to be supporting cells although they sustain physiologic neurogenesis in the adult CB and are thus supposed to be progenitor cells as well. The CB is a highly vascularized organ and its intraorgan hemodynamics possibly plays a role in the process of chemoreception.