A cohort study of duplex Doppler examinations of the carotid artery in primary open angle glaucoma

Objectives To explore the possibility of pathological change in the common carotid artery at the bifurcation and in the internal carotid artery beyond the bifurcation which could contribute to a reduced diastolic pressure as observed in primary open angle glaucoma. Design Duplex ultrasonic examinations of carotid bifurcations were conducted on 80 patients. Carotid artery defects were allocated into three types: no demonstrable flow defects, internal carotid artery abnormalities and disease in the carotid bulb. Setting Bristol Royal Infirmary Vascular Laboratory. Participants Eighty patients (mean age 69.6 years) providing a total of 160 sides to the analysis. Main outcome measures An estimated central retinal artery pressure, intraocular pressure and field loss were recorded for each side measured. Results Doppler investigations revealed significant levels of pathological change in the internal carotid distinct from changes at the carotid bulb. The disease revealed in the internal carotid artery was significantly associated with intraocular pressure (p = 0.032), with an effect small to medium in magnitude. The Q2 measure, derived from mean arterial pressure and intraocular pressure, was also substantively associated with disease in the internal carotid artery. Both intraocular pressure and the Q2 measure effectively discriminated between groups, with field loss providing rather less discriminating capability. There was a strong trend towards a higher intraocular pressures and a greater visual field loss with internal carotid artery disease. Conclusions Pathological changes in the extra cranial carotid artery in primary open angle glaucoma exceed those in the arteries classified as normal. The presence of disease specifically in the internal carotid artery emphasised the need for a mechanism for the evaluation of the internal carotid apart from the carotid bulb. A basis for clarifying the presence of an ischaemic zone is proposed

Length of carotid stenosis predicts peri-procedural stroke or death and restenosis in patients randomized to endovascular treatment or endarterectomy.

BACKGROUND: The anatomy of carotid stenosis may influence the outcome of endovascular treatment or carotid endarterectomy. Whether anatomy favors one treatment over the other in terms of safety or efficacy has not been investigated in randomized trials. METHODS: In 414 patients with mostly symptomatic carotid stenosis randomized to endovascular treatment (angioplasty or stenting; n = 213) or carotid endarterectomy (n = 211) in the Carotid and Vertebral Artery Transluminal Angioplasty Study (CAVATAS), the degree and length of stenosis and plaque surface irregularity were assessed on baseline intraarterial angiography. Outcome measures were stroke or death occurring between randomization and 30 days after treatment, and ipsilateral stroke and restenosis ≥50% during follow-up. RESULTS: Carotid stenosis longer than 0.65 times the common carotid artery diameter was associated with increased risk of peri-procedural stroke or death after both endovascular treatment [odds ratio 2.79 (1.17-6.65), P = 0.02] and carotid endarterectomy [2.43 (1.03-5.73), P = 0.04], and with increased long-term risk of restenosis in endovascular treatment [hazard ratio 1.68 (1.12-2.53), P = 0.01]. The excess in restenosis after endovascular treatment compared with carotid endarterectomy was significantly greater in patients with long stenosis than with short stenosis at baseline (interaction P = 0.003). Results remained significant after multivariate adjustment. No associations were found for degree of stenosis and plaque surface. CONCLUSIONS: Increasing stenosis length is an independent risk factor for peri-procedural stroke or death in endovascular treatment and carotid endarterectomy, without favoring one treatment over the other. However, the excess restenosis rate after endovascular treatment compared with carotid endarterectomy increases with longer stenosis at baseline. Stenosis length merits further investigation in carotid revascularisation trials

The baroreceptor reflex emanating from the carotid sinus and common carotid artery of the sheep : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Physiology at Massey University

The aim of this project was to improve understanding of the role of the common carotid arterial baroreceptor mechanism in controlling peripheral blood pressure in the sheep. The responses to clamping of one or both common carotid arteries were examined under chloralose anaesthesia with the vagus nerves intact and after they had been sectioned. Unilateral clamping of a common carotid artery immediately reduced the mean blood pressure and pulse pressure in the ipsilateral carotid sinus and raised the peripheral mean blood pressure and pulse pressure. The failure of sinus pressures to show any recovery in the clamped vessel suggests that there was minimal flow through anastomoses into the occluded artery. Bilateral clamping of the common carotid arteries reduced the mean blood pressure within both carotid sinuses to a lower level than unilateral clamping, but raised the peripheral mean blood pressure and pulse pressures to a greater degree. This pressor response was interpreted as being due to the larger population of baroreceptors detecting the low carotid sinus pressures during bilateral occlusion. To test whether there was a tendency for common carotid arterial clamping at different levels to produce different reflex responses of peripheral blood pressure, the carotid arteries were occluded at the caudal, mid- and cranial cervical levels. There was a trend towards a greater rise in peripheral mean blood pressure during caudal clamping compared with cranial clamping. This too may be due to a larger population of baroreceptors detecting the low carotid sinus and common carotid arterial pressures and suggests baroreceptors are distributed in regions of the common carotid artery caudal to the sinus. In one third of the sheep, clamping the left common carotid artery caused a greater rise in peripheral mean blood pressure than clampinq of the right vessel. Possible reasons for this include the presence of a larger population of baroreceptors in the left artery than the right and differences in the sensitivity of receptors in the two vessels. The variability of responses to clamping and vagotomy was emphasised by the responses of two sheep in which section of the right vagus nerve totally abolished the reflex response to right common carotid arterial occlusion. Since in these animals neither the size of the baroreceptor population nor its sensitivity appeared to be responsible, a conclusion consistent with the evidence is that the baroreceptors in the vessel were innervated by the recurrent laryngeal or vagus nerves. Overall in the experiments, bilateral vagotomy enhanced the peripheral mean blood pressure and pulse pressure responses to clamping the common carotid arteries in keeping with a loss of the input from the aortic arch and cardio-pulmonary baroreceptors. Histological evidence of the distribution of sensory areas along the common carotid artery was obtained for three discrete areas (A, B and C). It is suggested that baroreceptors located in the common carotid artery may be less sensitive than those in the carotid sinus region because of the low elastin content and lack of tunica medial thinning at the sites of carotid arterial baroreceptor innervation

Resolution of Occlusive Carotid Artery Thrombus Treated with Anticoagulation as Demonstrated on Duplex Ultrasonography.

BACKGROUND AND PURPOSE: While the majority of cerebral ischemic events due to carotid occlusive disease result from atherosclerotic plaque rupture, intraluminal carotid artery thrombus occasionally occurs in patients without preexisting carotid atherosclerosis. Identification of nonatherosclerotic thrombus as the cause of the carotid occlusive disease can obviate the need for an interventional procedure, and resolution of thrombus can be monitored with B-mode duplex ultrasonography. METHODS: We reviewed 3 patients treated on The Mount Sinai Hospital Stroke Unit with anticoagulation for nonatherosclerotic carotid thrombi and followed with serial Doppler ultrasonogrpahy for resolution of thrombus. RESULTS: Occlusive carotid thrombus was successfully treated in all 3 patients with systemic anticoagulation. B-mode duplex ultrasonography allowed for demonstration of resolving thrombus. CONCLUSION: Differentiation between a stenotic plaque and occlusive thrombus can be achieved by ultrasonographic analysis of thrombus morphology, attachment site potential, and characteristics of a resolving thrombus. Systemic anticoagulation can safely and effectively eliminate the risk for future embolization and complete occlusion of the carotid artery in patients who present with transient ischemic events or completed infarcts of small size

Can Emergency Physicians Perform Carotid Artery Point-of-Care Ultrasound to Detect Stenosis in Patients with TIA and Stroke? A Pilot Study

Introduction: Patients with severe, symptomatic carotid stenosis can have their subsequent stroke risk reduced by surgical intervention if performed soon after a transient ischemic attack (TIA) or stroke. Patients presenting to an emergency department (ED) without computed tomography angiography (CTA) with TIA/stroke, may require transfer to another hospital for imaging to rule out carotid artery stenosis. The objective of this study was to determine the test characteristics of carotid artery point-of-care ultrasound (POCUS) in detecting greater than 50% stenosis in patients presenting with TIA/stroke.Methods: We conducted a prospective cohort study on a convenience sample of adult patients presenting to a comprehensive stroke centre with TIA or stroke between June–October 2017. Carotid POCUS was performed. Primary outcome measure, stenosis ≥ 50%, was determined by the final radiology report of CTA. A blinded POCUS expert separately reviewed the archived carotid POCUS scans. We calculated sensitivity and specificity for stenosis ≥ 50%.Results: We conducted POCUS on 75 patients, of which 70 were included in our analyses. Of those 70, 14.3% were diagnosed with greater than 50% stenosis. Carotid POCUS performed as follows: sensitivity 70.0% (95% confidence interval [CI], 34.8%-93.3%); specificity 86.7% (95% CI, 75.4%-94.1%); positive likelihood ratio (LR +) 5.3 (95% CI, 1.2-9.3); negative likelihood ratio (LR -) 0.4 (95% CI, 0.0-0.7). The inter-rater reliability between POCUS performer interpretation and expert interpretation had moderate agreement (k = 0.68). Scans took a mean 6.2 ± 2.2 minutes to complete.Conclusion: Carotid POCUS has low to moderate association with CTA for detection of carotid artery stenosis ≥ 50%. Further research and investigation is needed prior to widespread use of carotid POCUS in patients with acute cerebral ischemia. Additionally, external validity is likely affected by availability of training, maintenance of competency, and experience in more rural centres

Carotid endarterectomy : the Maltese experience

Introduction: Carotid endarterectomy significantly reduces the risk of cerebrovascular events in both symptomatic and asymptomatic patients with significant carotid stenosis. The recent American Heart Association/American College of Cardiology guidelines advise that carotid endarterectomy is only beneficial when the perioperative stroke or mortality rate is below 6%. The aim of this study was to review the results of carotid endarterectomy performed in Malta by one vascular surgeon. Methods: All patients undergoing carotid endarterectomy between July 2007 and June 2011 were included in the study. Data was entered prospectively into a vascular database. Retrospective review of the case notes of all patients undergoing carotid endarterectomy was also performed. Demographics of the patient cohort as well as information about perioperative mortality, cerebrovascular events, cardiac events as well as any other complications were recorded. Information was also collected about any deaths and cerebrovascular events during the follow up period. Results: 51 patients underwent carotid endarterectomy during the study period. 94% were symptomatic (65% CVA; 15% TIA; 10% amaurosis fugax; 4% TIA and amaurosis) and 6% asymptomatic. 46% had an internal carotid artery stenosis of 90% or more while the rest had a stenosis of 70% or more. 31% of patients also had significant contralateral carotid stenosis or occlusion. There was one postoperative mortality (1.9%) and one patient sustained a postoperative lacunar stroke (1.9%). There were no cranial nerve injuries and no bleeding requiring return to theatre. The combined perioperative mortality and stroke rate in this cohort was 3.9%. Conclusions: The combined perioperative mortality and stroke rate in this sutdy is better than that reported in the major randomised controlled trials. The perioperative death and stroke rate is well below the threshold level advised by the AHA/ACC.peer-reviewe

Hypoglossal schwannoma masquerading as a carotid body tumor.

Study Objective. To describe the clinical presentation, evaluation, and treatment of a hypoglossal schwannoma. Methods. We report an unusual case of a hypoglossal schwannoma presenting as a pulsatile level II neck mass at the bifurcation of the external and internal carotid arteries, mimicking a carotid body tumor. Radiologic findings are reviewed in detail. Results. A 59-year-old female presented to a tertiary care medical center with complaints of a pulsatile right-sided neck mass. An MRA of the neck was obtained demonstrating a 5 cm mass located at the carotid artery bifurcation and causing splaying of the internal and external carotids. Based on clinical presentation and imaging, a diagnosis of a carotid body tumor was conferred and the patient scheduled for excision. Intraoperatively, the mass was noted to arise from the hypoglossal nerve, remaining independent of the carotid artery. On histopathologic analysis, the mass was determined to be consistent with hypoglossal schwannoma. Conclusion. Though rare, the hypoglossal schwannoma should remain a consideration in the evaluation of a parapharyngeal space mass. As this report demonstrates, the clinical and radiologic presentation of a hypoglossal schwannoma may closely mimic that of the more common carotid body tumor

A role for TASK-1 (KCNK3) channels in the chemosensory control of breathing

Acid-sensitive K+ channels of the tandem P-domain K+-channel family (TASK-1 and TASK-3) have been implicated in peripheral and central respiratory chemosensitivity; however, because of the lack of decisive pharmacological agents, the final proof of the role of the TASK channel in the chemosensory control of breathing has been missing. In the mouse, TASK-1 and TASK-3 channels are dispensable for central respiratory chemosensitivity (Mulkey et al., 2007Go). Here, we have used knock-out animals to determine whether TASK-1 and TASK-3 channels play a role in the carotid body function and chemosensory control of breathing exerted by the carotid body chemoreceptors. Ventilatory responses to hypoxia (10% O2 in inspired air) and moderate normoxic hypercapnia (3–6% CO2 in inspired air) were significantly reduced in TASK-1 knock-out mice. In contrast, TASK-3-deficient mice showed responses to both stimuli that were similar to those developed by their wild-type counterparts. TASK-1 channel deficiency resulted in a marked reduction of the hypoxia (by 49%)- and CO2 (by 68%)-evoked increases in the carotid sinus nerve chemoafferent discharge recorded in the in vitro superfused carotid body/carotid sinus nerve preparations. Deficiency in both TASK-1 and TASK-3 channels increased baseline chemoafferent activity but did not cause a further reduction of the carotid body chemosensory responses. These observations provide direct evidence that TASK-1 channels contribute significantly to the increases in the carotid body chemoafferent discharge in response to a decrease in arterial PO2 or an increase in PCO2/[H+]. TASK-1 channels therefore play a key role in the control of ventilation by peripheral chemoreceptors

A horse, a horse, my kingdom for a horse. Saddle thrombosis of carotid bifurcation in acute stroke

Background: Saddle thrombosis is less frequently detected in carotid arteries than in peripheral arterial embolism. The clot and the distal vessel patency have to be promptly recognized in these cases, because if the carotid vessel is open distally, chances may arise for successful emergent surgical procedures to remove the thrombus. At conventional static imaging, mobile floating thrombi may be difficult to differentiate from thrombosis on carotid complicated lesions of atherosclerotic origin. High-resolution ultrasound (US), with its unique capability of real-time imaging, adds fundamental data for interpretation of the findings. Methods: Carotid ultrasound has been performed in acute stroke patients with high-resolution probes. Real-time clips are analyzed and imaging is presented. Results: Saddle carotid bifurcation thrombosis of cardiac origin has been identified in 2 patients with acute homolateral ischemic stroke, with prompt successful surgical removal in one case. Moreover, an example of a thrombus attached on the ruptured surface of a complicated atherosclerotic plaque in an acute symptomatic stroke patient that was successfully operated in emergency is presented. Conclusions: Early high-resolution ultrasound with real-time imaging can easily identify peculiar characteristics of carotid vulnerable diseases in acute stroke phase. Different clinical implications result from the early identification of these different conditions, modifying the therapeutical strategies. © 2012 Elsevier GmbH

Natriuretic peptide receptor-C is up-regulated in the intima of advanced carotid artery atherosclerosis

OBJECTIVE: Natriuretic peptide receptor-C (NPR-C/NPR-3) is a cell surface protein involved in vascular remodelling that is up-regulated in atherosclerosis. NPR-C expression has not been well characterized in human carotid artery occlusive lesions. We hypothesized that NPR-C expression correlates with intimal features of vulnerable atherosclerotic carotid artery plaque. METHODS: To test this hypothesis, we evaluated NPR-C expression by immunohistochemistry (IHC) in carotid endarterectomy (CEA) specimens isolated from 18 patients. The grade, location, and co-localization of NPR-C in CEA specimens were evaluated using two tissue analysis techniques. RESULTS: Relative to minimally diseased CEA specimens, we observed avid NPR-C tissue staining in the intima of maximally diseased CEA specimens (65%; p=0.06). Specifically, maximally diseased CEA specimens demonstrated increased NPR-C expression in the superficial intima (61%, p=0.17), and deep intima (138% increase; p=0.05). In the superficial intima, NPR-C expression significantly co-localized with vascular smooth muscle cells (VSMCs) and macrophages. The intensity of NPR-C expression was also higher in the superficial intima plaque shoulder and cap regions, and significantly correlated with atheroma and fibroatheroma vulnerable plaque regions (β=1.04, 95% CI=0.46, 1.64). CONCLUSION: These findings demonstrate significant NPR-C expression in the intima of advanced carotid artery plaques. Furthermore, NPR-C expression was higher in vulnerable carotid plaque intimal regions, and correlate with features of advanced disease. Our findings suggest that NPR-C may serve as a potential biomarker for carotid plaque vulnerability and progression, in patients with advanced carotid artery occlusive disease