Stenotic occlusive lesions of internal carotid artery in diabetic patients

Diabetes deteriorates atherosclerotic changes in the arteries. The aim of the study was to assess the prevalence and localization of stenotic atherosclerotic lesions of the internal carotid artery (ICA) in patients with diabetes. A prospective analysis of angiography findings was carried out in 150 diabetic and 150 non-diabetic patients with symptoms of cerebral ischemia using double-blind angiogram readings by two independent investigators. The degree of stenosis was determined using the North American Symptomatic Carotid Endarterectomy Trial (NASCET) criteria. Stenoses of the proximal arterial segment accounted for the majority of extracranial ICA stenoses, being more frequent in diabetic (left ICA 50.7%, right ICA 58.0%) than in the non-diabetic patients (left ICA 29.3%, right ICA 32.7%). Diabetic patients revealed a more significant rate of unilateral tandem ICA stenoses (14.0-21.3%), as well as a statistically significantly higher prevalence of intracranial ICA stenoses (left ICA 24.0% and right ICA 17.3%) than did non-diabetic patients (left and right ICA 3.3% each). Our results confirm that there is a morphological basis in ICA for increased incidence of ICA lesions in patients with diabetes as compared to those without it. Data on the incidence of stenotic ICA lesions in diabetes suggest the importance of assessing overall ICA status using digital subtraction angiography. Such an assessment is a precondition for an optimal therapeutic approach, especially in diabetic patients who are at an increased risk of cerebrovascular disease.     

The baboon (Papio anubis) extracranial carotid artery: An anatomical guide for endovascular experimentation

Background  

As novel endovascular strategies are developed for treating neurological disease, there is an increasing need to evaluate these techniques in relevant preclinical models. The use of non-human primates is especially critical given their structural and physiological homology with humans. In order to conduct primate endovascular studies, a comprehensive understanding of the carotid anatomy is necessary. We therefore performed a detailed examination of the vessel lengths, lumen diameters and angles of origin of the baboon extracranial carotid system.     

Platelet aggregability in patients with common carotid artery ligation

Increased platelet aggregability is regarded as being a sensitive indicator of the initiation of thrombotic processes. Platelet aggregation was analysed in blood taken from the common carotid artery before and 30 min after its ligation in 3 patients, as well as in the venous blood of 14 patients in the late postoperative period. No tendency towards increasing platelet aggregation was observed in either of the groups investigated.     

Wall stress of the cervical carotid artery in patients with carotid dissection: a case-control study

Spontaneous internal carotid artery (ICA) dissection (sICAD) results from an intimal tear located around the distal carotid sinus. The mechanisms causing the tear are unknown. This case-control study tested the hypotheses that head movements increase the wall stress in the cervical ICA and that the stress increase is greater in patients with sICAD than in controls. Five patients with unilateral, recanalized, left sICAD and five matched controls were investigated before and after maximal head rotation to the left and neck hyperextension after 45° head rotation to the left. The anatomy of the extracranial carotid arteries was assessed by magnetic resonance imaging and used to create finite element models of the right ICA. Wall stress increased after head movements. Increases above the 80th and 90th percentile were located at the intimal side of the artery wall from 7.4 mm below to 10 mm above the cranial edge of the carotid sinus, i.e., at the same location as histologically confirmed tears in patients with sICAD. Wall stress increase did not differ between patients and controls. The present findings suggest that wall stress increases at the intimal side of the artery wall surrounding the distal edge of the carotid bulb after head movements may be important for the development of carotid dissection. The lack of wall stress difference between the two groups indicates that the carotid arteries of patients with carotid dissection have either distinct functional or anatomical properties or endured unusually heavy wall stresses to initiate dissection.     

Variations in the extracranial origin of the human vertebral artery

The aim of this study is to demonstrate a case of a cadaver in which both left and right vertebral arteries had an abnormal origin. On the left, the artery arose directly from the arch of the aorta. On the right, a double-originating vertebral artery was seen. The literature on the variations of the artery is reviewed and a detailed morphometric study of the artery was carried out because of its importance for neurosurgeons.     

Adjunctive pharmacologic treatment for elective stenting of the extracranial carotid arteries

Endovascular stenting of the extracranial carotid arteries is a viable treatment option to carotid endarterectomy in selected patients. Patients undergoing this procedure must be treated with aspirin 325 mg at least 24 hours prior to the procedure and clopidogrel 75 mg oral, three to five days prior to the procedure (or 300 mg at least six hours prior to stenting). During the intervention, heparin is given to maintain an activated clotting time of at least 300 seconds. Although there are theoretical advantages on the use of a platelet IIb/IIIa inhibitor, their routine use during elective carotid stenting is not recommended until their clinical benefits have been clearly demonstrated in this patient population. Hemodynamic instability during balloon inflation and stent deployment should be treated with intravenous fluids, atropine, and an alpha agonist such as neosynephrine. All the oral antihypertensive must be discontinued after the procedure and if there is persistence of hypotension making discontinuation of neosynephrine difficult, an oral alpha agonist such as midodrine (2.5 to 5 mg two to three times daily) is helpful. In the majority of patients this medication can be tapered off three to five days following stenting.     

Standardized ultrasound evaluation of carotid stenosis for clinical trials: University of Washington Ultrasound Reading Center

Introduction

Serial monitoring of patients participating in clinical trials of carotid artery therapy requires noninvasive precision methods that are inexpensive, safe and widely available. Noninvasive ultrasonic duplex Doppler velocimetry provides a precision method that can be used for recruitment qualification, pre-treatment classification and post treatment surveillance for remodeling and restenosis. The University of Washington Ultrasound Reading Center (UWURC) provides a uniform examination protocol and interpretation of duplex Doppler velocity measurements.

Methods

Doppler waveforms from 6 locations along the common carotid and internal carotid artery path to the brain plus the external carotid and vertebral arteries on each side using a Doppler examination angle of 60 degrees are evaluated. The UWURC verifies all measurements against the images and waveforms for the database, which includes pre-procedure, post-procedure and annual follow-up examinations. Doppler angle alignment errors greater than 3 degrees and Doppler velocity measurement errors greater than 0.05 m/s are corrected.

Results

Angle adjusted Doppler velocity measurements produce higher values when higher Doppler examination angles are used. The definition of peak systolic velocity varies between examiners when spectral broadening due to turbulence is present. Examples of measurements are shown.

Discussion

Although ultrasonic duplex Doppler methods are widely used in carotid artery diagnosis, there is disagreement about how the examinations should be performed and how the results should be validated. In clinical trails, a centralized reading center can unify the methods. Because the goals of research examinations are different from those of clinical examinations, screening and diagnostic clinical examinations may require fewer velocity measurements.     

Cerebral perfusion changes in patients with internal carotid artery stenoses after surgical revascularization

Changes of cerebral perfusion and the condition of collateral blood supply in patients with internal carotid artery stenoses may have a prognostic value for effective blood flow restoration after revascularization of the internal carotid arteries (ICAs). To determine the patterns of cerebral perfusion changes in patients with ICA stenoses before and after surgical treatment, a clinical CT perfusion study of 41 patients with moderate to severe ICA stenoses was performed. Perfusion CT (PCT) had been conducted in 17 patients with moderate ICA stenoses (50–69%) and in 24 patients with severe ICA stenoses (70–99%) 3 times: before intervention (balloon angioplasty with stenting or carotid endarterectomy), on the 3rd to 7th day, and within 1 to 3 months after surgery. Scanning was performed at the level of the basal ganglia and semioval centers. In patients without ICA stenosis (control group of 39 individuals), PCT was conducted once. We found that surgical recanalization of the ICA leads to normalization of the cerebral blood flow parameters in the perfusion area of the middle cranial artery, as evidenced by a decrease of MTT and CBV and an increase of CBF to values comparable to those in the control group. However, blood flow restoration in the anterior and posterior watershed areas, which are known to be mostly affected under chronic hypoperfusion conditions, was observed only in patients with a complete circle of Willis (CW) and moderate ICA stenosis. Therefore, severe stenosis (>70%) and the incomplete CW are the prognostic factors for inadequate blood flow restoration after revascularization in patients with ICA stenoses.     

Perioperative and early postoperative neurological deficit in older patients during carotid artery thrombendarterectomy

Cerebrovascular accidents, strokes in particular, are among the most frequent causes of death today in developed countries. In the last two decades, stroke was the second most frequent cause of death in Primorsko-Goranska Region in Croatia. In older patients, individuals older than 65 years of age have an increased risk of stroke, mainly because the degree of carotid artery stenosis increases with age. The most frequent complication of the high percent stenosis of the carotid arteries is thrombosis in the area of atherosclerotic changes of blood vessels. With the increase in the age of the population, there is also an increase in the number of risk factors of cerebrovascular accident. Doppler ultrasound sonography and Multi Slice CT scans have the most prominent role in the early detection of atherosclerotic changes and in the assessment of the degree of carotid artery narrowing. Today, in Croatia as well as worldwide, thrombendarterectomy holds the most important place in stroke prevention. Between 2006 and 2009, 209 patients underwent surgical intervention at the Clinical Hospital Center in Rijeka for high degree of carotid artery narrowing. In the group younger than 65 years of age, which consisted of 53 patients, a neurological deficit was noted in 4 patients (7.54%) in the perioperative and early postoperative course. In the group of individuals older than 65 years of age, which consisted of 156 patients, a neurological deficit was noted in 9 patients (5.76%). There was no significant statistical difference in the incidence of neurological deficit, nor in the mortality in individuals older than 65 years of age during carotid arteries thrombendarterectomy.     

Longitudinal MRI study on the natural history of carotid artery plaques in symptomatic patients

Purpose

To investigate the natural history of carotid atherosclerosis in patients who experienced a TIA or ischemic stroke.

Patients and Methods

Ninety-two TIA/stroke patients (57 men, mean age 67.7±9.8 years) with ipsilateral <70% carotid stenosis underwent multisequence MRI of the plaque ipsilateral to the symptomatic side at baseline and after one year. For each plaque, several parameters were assessed at both time points.

Results

Carotid lumen, wall and total vessel ( = carotid lumen and wall) volume did not significantly change. Forty-four patients had a plaque with a lipid-rich necrotic core (LRNC) at baseline, of which 34 also had a LRNC after one year. In three patients a LRNC appeared after one year. Thirty patients had a plaque with a thin and/or ruptured fibrous cap (FC) at both time points. In seven patients, FC status changed from thin and/or ruptured into thick and intact. In three patients, FC status changed from thick and intact into thin and/or ruptured. Twenty patients had intraplaque hemorrhage (IPH) at both time points. In four patients, IPH disappeared, whereas in three patients, new IPH appeared at follow-up.

Conclusion

In TIA/stroke patients, carotid plaque morphology does not significantly change over a one-year period. IPH and FC status change in a minority of patients.