Air Pollution Role as Risk Factor of Cardioinhibitory Carotid Hypersensitivity

Little is known about the impact of air pollution on neuroautonomic system. The authors have investigated possible influence of air pollution and outdoor temperature on the carotid sinus hypersensitivity (CSH), as main cause of neurally mediated syncope in forty-years-old subjects and older. Pollutants’ concentrations and outdoor temperature of days in which 179 subjects with recurrent syncope underwent carotid sinus massage (CSM) were analyzed. Before this manoeuvre, cardiovascular control by short period heart and blood pressure spectral duration of segment between the end of P and R ECG-waves (PeR) were registred; RR variability on the same short period ECG recordings and their spectral coherence were also analyzed. CSH was found in 57 patients (28 with cardioinhibitory response and 29 subjects showed vasodepressor reaction), while 122 subjects had a normal response. CSM performed during high ozone concentrations was associated with slightly higher risk of cardioinhibitory response (odd ratio 1.012, 95% CI 1.001–1.023, p < 0.05), but neither this or other polluting agent nor outdoor temperature seemed to influence autonomic control in basal resting condition. Thus, ozone seemed to influence response to the CSM in CSH patients and it is probably able to facilitate a cardioinhibitory response, perhaps through an increase of nerve acetylcholine release. P→PR coherence could be useful in predicting a sinus cardioinhibitory hypersensitivity in those cases when CSM is contraindicated.

HISTOMORPHOLOGICAL STUDY ON THE CAROTID SINUS IN RABBIT

Histomorphological study confirmed that the carotid sinus was characterized by an abrupt thinning of elastic tunica media which was rapidly replaced by the normal muscularity of the media on the distal progression in the internal carotid artery. The carotid sinus was richly supplied with sensory receptors which took the form of menisci and left the sinus as the nerve of Hering.

Syncope as the Initial Manifestation of Advanced Nasopharyngeal Carcinoma: A Case Report

Carotid sinus syndrome is a principal cause of syncope in the elderly. Syncope, associated with carotid sinus syndrome which is secondary to metastasis of advanced nasopharyngeal carcinoma, rarely occurs. The current study reported a 66-year-old woman, who presented with a history of frequent and recurrent syncope as the initial symptom, and was eventually diagnosed with advanced nasopharyngeal carcinoma. The positron emission tomography scan demonstrated a diagnosis of advanced nasopharyngeal carcinoma with involvement in carotid sheath space, and nasopharyngeal biopsy revealed non-keratinized nasopharyngeal carcinoma. After diagnosis and treatment, the patient had no recurrence of syncope. In summary, our case study suggests that great importance should be attached to potential intrinsic causes of syncope especially in the case of nasopharyngeal carcinoma, as it is an insidious malignancy which needs to be precisely identified.

Blood Pressure Regulation by the Carotid Sinus Nerve: Clinical Implications for Carotid Body Neuromodulation

Chronic carotid sinus nerve (CSN) electrical modulation through kilohertz frequency alternating current improves metabolic control in rat models of type 2 diabetes, underpinning the potential of bioelectronic modulation of the CSN as a therapeutic modality for metabolic diseases in humans. The CSN carries sensory information from the carotid bodies, peripheral chemoreceptor organs that respond to changes in blood biochemical modifications such as hypoxia, hypercapnia, acidosis, and hyperinsulinemia. In addition, the CSN also delivers information from carotid sinus baroreceptors—mechanoreceptor sensory neurons directly involved in the control of blood pressure—to the central nervous system. The interaction between these powerful reflex systems—chemoreflex and baroreflex—whose sensory receptors are in anatomical proximity, may be regarded as a drawback to the development of selective bioelectronic tools to modulate the CSN. Herein we aimed to disclose CSN influence on cardiovascular regulation, particularly under hypoxic conditions, and we tested the hypothesis that neuromodulation of the CSN, either by electrical stimuli or surgical means, does not significantly impact blood pressure. Experiments were performed in Wistar rats aged 10–12 weeks. No significant effects of acute hypoxia were observed in systolic or diastolic blood pressure or heart rate although there was a significant activation of the cardiac sympathetic nervous system. We conclude that chemoreceptor activation by hypoxia leads to an expected increase in sympathetic activity accompanied by compensatory regional mechanisms that assure blood flow to regional beds and maintenance of hemodynamic homeostasis. Upon surgical denervation or electrical block of the CSN, the increase in cardiac sympathetic nervous system activity in response to hypoxia was lost, and there were no significant changes in blood pressure in comparison to control animals. We conclude that the responses to hypoxia and vasomotor control short-term regulation of blood pressure are dissociated in terms of hypoxic response but integrated to generate an effector response to a given change in arterial pressure.

Cardiac Pacing in Cardioinhibitory Reflex Syncope: Clinical Use of Closed-loop Stimulation

Cardiac pacing has been studied extensively in patients with reflex syncope over the past two decades. The heterogeneity of the forms and clinical manifestations of reflex syncope explain the controversial results of older randomised clinical trials. New evidence from recent trials has changed medical practice, now leading to clear indications for pacing in patients with asystolic syncope documented during carotid sinus massage, implantable cardiac monitoring or tilt testing. Given that recent trials in reflex syncope have been performed using the closed-loop stimulation algorithm, the authors will briefly discuss this pacing mode, review hypotheses about the mechanisms underlying its activation during syncope and provide practical instructions for programming and troubleshooting.

Left hemispheric cortical watershed infarcts triggered by carotid sinus self-massage

A 69-year-old man was presented to our emergency department with acute onset of hemianopsia, aphasia and dizziness. He reported that while he was sitting in front of his computer at home, he had performed a bilateral self-massage of his carotid arteries when suddenly the symptoms occurred. A neurological examination revealed a hemianopsia with a visual field loss on the right side. In addition, a mild aphasic syndrome with agraphia and a word-finding disorder (National Institutes of Health Stroke Scale (NIHSS): 3 points) was diagnosed. The initial brain CT scan with CT angiography showed neither an intracerebral haemorrhage nor a cerebral infarction. Also, no occlusion or any signs of artery dissection or a flow relevant stenosis of the brain supplying arteries were found. After excluding other contraindications, an intravenous thrombolysis with weight-adapted alteplase was performed. The symptoms of the patient significantly improved in the short-term follow-up. Three days after admission no neurological deficits remained. The MRI of the brain revealed multifocal, small, left hemispherical strokes in the middle cerebral artery territory. In general, watershed infarcts after carotid sinus self-massage follow a rare ischaemic stroke mechanism. This case emphasises the importance of a detailed anamnestic evaluation to determine the aetiological classification of ischaemic stroke as well as educating patients’ (poststroke) behaviour.

Repeated Cardiac Arrest Following Emergency Carotid Artery Stenting.- A Case Report.

Background: Due to carotid sinus response, blood pressure reduction and bradycardia during and after carotid stent implantation was reported frequently, in contrast, repeated cardiac arrest is rare but fatal unless the heart can be started quickly. Case introduction: A 61-year-old male presented with severe left hemiplegia, aphasia, central facial palsy and gaze. Emergency surgery under general anesthesia was finally scheduled in view of possible severe cerebral arterial stenosis. The patient underwent ipsilateral ICA stenting after balloon dilatation and was transferred to intensive care unit(ICU). His heart rate tended to decrease sharply and then cardiac arrest was noted on electrocardiograph(ECG) monitor. Emergency cardiopulmonary resuscitation(CPR) was started and repeated three times due to persistent symptoms. Coronary angiography was postponed for 15 days until neurological recovery. Multivessel disease with severe stenosis one of them was confirmed and percutaneous coronary intervention (PCI) was performed. The patient was discharged on the 20th day of admission with only slight neurological deficits. Conclusion: We tend to attribute the causes of repeated cardiac arrest in this case to carotid sinus response induced by stenting and serious coronary stenosis.

Carotid sinus syndrome in carotid angioplasty with stenting

Introduction. Significant progress has been made in primary stroke prevention, including through the widespread use of carotid angioplasty with stenting (CAS). At the same time, there is a growing number of publications reporting the development of carotid sinus syndrome (CSS) (haemodynamic instability) in the periope- rative period, as well as cerebral and cardiac complications and death, which requires in-depth study to improve the quality of medical care for patients with carotid artery stenosis. The aim of the study was to determine the frequency, risk factors, clinical features and outcomes of CSS in patients with carotid artery stenosis undergoing CAS. Materials and methods. The study included 120 patients with carotid artery disease, who underwent an elective surgical intervention consisting of transluminal balloon angioplasty. All patients underwent comprehensive clinical and laboratory tests and imaging studies. Results. CSS developed in 70% of cases (n = 84) of carotid artery stenosis, and was significantly more common in men than women (71.4% vs. 28.6%, respectively) (p 0.05). The median age of all patients with CSS was 68 (4491) years. Mixed form of CSS was significantly more common than the cardioinhibitory or vasodepressor forms (p 0.05). In more than half of all cases, symptoms developed during balloon dilatation or within an hour afterwards. The duration of CSS was 3040 hours. Contralateral carotid occlusion was detected in 12 (10%) patients, significantly (p 0.05) more often in patients with CSS (13%) compared to patients without CSS (2.8%). Conclusion. Regardless of stenosis severity or symptoms, CAS is accompanied by CSS in 2/3 of cases. The CSS is predominantly a mixed type and can be accompanied by loss of consciousness in rare cases. CSS appears both intraoperatively and in the early postoperative period, and its average duration is 1.5 days. A factor that may be associated with CSS development is contralateral carotid artery occlusion (p 0.05).

Prediction of Resthenosis After Carotid Endarterectomy by the Method of Computer Simulation

The article describes a computer modeling technique that allows predicting the development of restenosis of the internal carotid artery after carotid endarterectomy (CEE). A clinical case has been demonstrated that proves the effectiveness of the developed method. It is indicated that for the correct formation of the geometric model, data from multispiral computed tomography with angiography of the patient after CEE with a layer thickness of 0.6 mm and a current of 355 mA are required. To build a flow model, data of color duplex scanning in three sections are required: 1. In the proximal section of the common carotid artery (3 cm proximal to the bifurcation); 2. In the section of the external carotid artery, 2 cm distal to the carotid sinus; 3. In the section of the internal carotid artery, 2 cm distal to the carotid sinus. The result of computer calculations using specialized software (Sim Vascular, Python, Open Foam) is a mathematical model of blood flow in a vessel. It is an array of calculated data describing the speed and other characteristics of the flow at each point of the artery. Based on the analysis of RRT and TAWSS indicators, a computer model of bifurcation is formed, which makes it possible to predict areas of increased risk of restenosis development. Thus, the developed technique is able to identify a cohort of patients after CEE, subjected to a high probability of loss of the vessel lumen. Such an opportunity will provide a more precise supervision of these patients in the postoperative period with the aim of early diagnosis of restenosis and timely prevention of the development of adverse cardiovascular events.

Hemodynamic Study of Blood Flow in the Carotid Artery with a Focus on Carotid Sinus Using Fluid-Structure Interaction

The carotid artery is one of the most favorable locations for atherosclerotic plaque accumulation due to its unique geometry. It predominantly occurs at the outer wall of the inner carotid artery (ICA) carotid sinus. Fluid-structure interaction study of hemodynamics in the carotid artery with a focus on carotid sinus plays a prominent role in explaining the development and progression of the atherosclerotic lesion. In this study, hemodynamic parameters affecting the plaque accumulation in the carotid artery was investigated with a focus on the carotid sinus. An idealized carotid artery model was taken and hemodynamic parameters such as deformation, WSS, OSI, RRT, and Helicity were investigated. The atherosclerosis-prone carotid sinus region had significantly low WSS, and low helicity resulting in higher OSI. In these regions, the flow separation had decreased the velocity significantly with a high-velocity angle. The flow divider had significant elevated WSS due to a higher pressure gradient. Stenosis is predicted to occur at the downstream area of the carotid sinus and develop downstream due to flow separation leading to endothelial dysfunction. Decreased vascular WSS, helicity, and higher OSI are key to the development of endothelial dysfunction leading to the atherosclerotic lesion at the carotid sinus.