Spontaneous history of asymptomatic internal carotid occlusion

The efficacy of STA-MCA double anastomosis comparing to single anastomosis in chronic internal carotid artery occlusion patients

OBJECTIVE

To investigate the efficacy of STA-MCA double-anastomosis and single-anastomosis in patients with cerebral hypoperfusion caused by chronic internal carotid artery occlusion(CICAO).

METHODS

In this retrospective study, data were collected from 19 patients with CICAO who underwent STA-MCA anastomosis at our hospital between January 2016 and January 2022, and they were divided into single anastomosis group and double anastomosis group according to the surgical method. The study collected general clinical data from both groups, including age, sex, lipid levels, blood pressure, glucose levels, smoking and alcohol consumption. Additionally, pre- and postoperative neurological function, cerebral hemodynamic parameters, and postoperative ischemic events were also recorded. By combining our study findings with the existing literature, a comparative analysis of the efficacy of single- and double-anastomosis in patients with CICAO was conducted.

RESULTS

Prior to surgical treatment，there were no statistically significant differences in cerebral hemodynamic parameters, including rob (0.65 ± 0.09 VS. 0.62 ± 0.04), rut (1.73 ± 0.40 VS. 1.99 ± 0.53), and rTMax (2.02 ± 0.49 VS. 1.72 ± 0.46), as well as neurofunctional scores, including modified Rankin Scale (MRS) (2.8 ± 1.03 VS. 2.4 ± 0.88) and National Institutes of Health Stroke Scale (NIHSS) (9.1 ± 5.08 VS. 8.3 ± 4.09) between the two groups. After operation, rCBF (single: 0.65 ± 0.09 VS.0.84 ± 0.08, p = 0.007; double: 0.62 ± 0.04 VS.1.08 ± 0.20, p = 0.001) were significantly increased in both groups, but the rMTT (1.99 ± 0.53 VS.1.27 ± 0.42, p = 0.0447) and rTMax (1.72 ± 0.46 VS.1.16 ± 0.16, p = 0.038) showed significant differences postoperatively only in the double-anastomosis group. The MRS (single: 1.8 ± 1.23, double: 1.7 ± 0.9) in both groups and the NIHSS (7.2 ± 5.11) in single-anastomosis group were not improved after surgery, while the NIHSS (8.3 ± 4.09 VS.4.4 ± 3.08, p = 0.037) in double-anastomosis group was improve significantly. In summary, the double-anastomosis group showed better improvement in rCBF and NIHSS scores compared to the single-anastomosis group.(ΔrCBF: 0.19±0.09 VS. 0.45±0.18, p=0.02, ΔNIHSS: 1.9±0.56 VS. 4±1.73, p=0.002). The cases were followed up for 20.3 ± 18.6 months, and there were no ischemic events in either group during the follow-up period.

CONCLUSION

STA-MCA revascularization can improve CBF in patients with hypoperfusion caused by CICAO, and prevent the reoccurrence of ischemic stroke effectively. Compared with single-anastomosis, double-anastomosis can provide more CBF and improve neurologic dysfunction.

Spotlight on clinical strategies of Chronic Internal Carotid Artery Occlusion: Endovascular interventions and external-intracarotid bypasses compared to conservative treatment

Chronic internal carotid artery occlusion (CICAO) has high prevalence and incidence rates, and patients with CICAO can be completely asymptomatic, experience a devastating stroke or die. It is important to note that CICAO causes cerebrovascular accidents. Currently, the external carotid-internal carotid (EC-IC) bypass technique is used to treat CICAO. However, many clinical studies showed that EC-IC bypass was not beneficial for many patients with CICAO. Meanwhile, endovascular intervention treatment options for CICAO are evolving, and an increasing number of patients are undergoing endovascular intervention therapy. Accordingly, a review comparing both techniques is warranted. For this review, we searched PubMed and collected relevant case study reports comparing endovascular interventional therapy and internal and external cervical bypass surgeries to provide strategies for clinical treatment.

Surgical therapy for chronic internal carotid artery occlusion: a systematic review and meta-analysis

Chronic internal carotid artery occlusion (CICAO) significantly increases the risk of recurrent stroke. Given unfavorable outcomes, revascularization procedures are not generally recommended for CICAO. In the last several years, loads of studies reported successful surgical revascularization for CICAO with promising success rate and favorable short-term outcomes. Meanwhile, due to the lack of high-quality evidence, the safety and efficacy of revascularization procedures remain debatable. This systematic review aims to scrutinize current evidence for the applicability of revascularization for CICAO. We also investigated potential predictors of postoperative prognosis. We searched clinical studies on surgical treatment of CICAO on the Medline, Cochrane library, and Embase databases, published from Jan 1990 to Jan 2021. Surgical operation was restricted to bypass surgery, endarterectomy, endovascular therapy, and hybrid surgery. Controlled clinical studies were included for clinical outcomes. Large-sample single-arm studies were supplemented to assess complications and success rate. Co-primary endpoints were technical success rate and neurological function; secondary endpoints were recurrent stroke/cerebrovascular events, complications, and deaths within follow-up. This systematic review has been registered in PROSPERO (CRD42020181250). One RCT and 5 cohort studies with a total of 465 patients were included in this review. Seven single-arm studies were supplemented for assessing success rate and complications. Bypass surgery presented the highest graft patency of 96% and a low incidence of complications, but no benefits on neurological function, recurrent stroke, or deaths. Endovascular therapy (carotid stenting) was characterized by a relatively lower technical success rate, significant neurological function recovery, and nonsignificant reduction of cerebrovascular events and deaths. Hybrid surgery was considered as a potential treatment for CICAO because of a high technical success rate and significant neurological improvement. Endarterectomy is only suitable for short-segment occlusion. Prospective clinical trials should focus on carotid stenting and hybrid surgery for their significant capacity of improving neurologic function and potential capacity of reducing deaths and cerebrovascular events.

Natural History of Symptomatic and Asymptomatic Carotid Artery Occlusion Contralateral to Carotid Endarterectomy: A Prospective Study

The natural history of carotid occlusion (CO) has generally been analyzed in the presence of a contralateral patent but diseased internal carotid artery (ICA). Few previous studies have focused on the fate of CO contralateral to the side of a prior carotid endarterectomy (CEA). The aim of this study was to analyze the mortality rate and the incidence of cerebrovascular events in the hemisphere ipsilateral to CO (HICO) in patients who had undergone contralateral CEA. The 30-day and long-term outcomes of 153 consecutive patients who had CEA for severe symptomatic and asymptomatic ICA lesions contralateral to a symptomatic or asymptomatic CO over a 15-year period were considered. The endpoints of the study were mortality and neurological events in the HICO. Overall, the 30-day mortality and stroke rates were 0.6% (1/153) and 1.9% (3/153), respectively; the only death was stroke-related and the stroke was ipsilateral to the operated side. The other 2 strokes were ipsilateral to a symptomatic CO. The follow-up was completed for all patients (mean, 7.7 years; range, 1-172 months). Overall, there were 4 late strokes (2.6%), one of them lacunar in a patient with a symptomatic CO, whereas the other 3 were atheroembolic and ipsilateral to the operated ICA. The risk of late stroke in the HICO at 5 and 12 years was 2%. Overall, there were 19 late deaths, none of them stroke-related. CO, with or without symptoms, contralateral to CEA could be considered a locally benign condition in the long term.

Carotid occlusion is associated with more frequent neurovascular events than moderately severe carotid stenosis

OBJECTIVE

Asymptomatic internal carotid artery occlusion (CO) presents a clinical dilemma, and presently, the natural history, stroke risk, and optimal management remain ill defined. This study compared outcomes, including neurovascular events (NVEs) and health care costs, between patients with CO and patients with asymptomatic carotid artery stenosis (CS).

METHODS

A prospectively maintained database was queried to identify patients with CO and CS with at least >50% carotid stenosis by duplex. We identified and reviewed 622 consecutive patients with asymptomatic carotid artery disease at one academic medical center between 2011 and 2013. Patients with CO (n = 97) were identified and propensity matched by age and gender in a 1:2 ratio with CS patients (n = 194) for further analyses. Univariate and multivariate models were used to analyze baseline characteristics, clinical variables, and 1-year follow-up data from the date of diagnosis. Multivariate analysis was performed by multiple linear regression modeling. Institutional Review Board approval was obtained.

RESULTS

Follow-up data were available for 99% of matched patients. CO patients were younger (72 vs 75 years; P < .01) and more likely male (67% vs 53%; P = .01) compared with CS patients. After propensity matching, baseline characteristics were similar between groups, with a trend toward higher use of statin therapy among patients with CO. Antiplatelet therapy was used in 79% of patients with CS and in 74% of patients with CO (P = .45). The rate of NVE among CO patients was higher than among CS patients at 1 year of follow-up (14% vs 7%; P = .03). Among those with NVE, neither antiplatelet therapy (64% vs 77%; P = .49) nor statin therapy (86% vs 77%; P = .58) appeared to have a significant effect. Health care costs ($14,361 vs $12,142; P = .44) and hospital admission rate (63% vs 71%; P = .18) were similar between groups. Not surprisingly, the rate of vascular procedures was higher in the CS group (55% vs 27%; P = .04).

CONCLUSIONS

Patients with asymptomatic CO experience more NVEs compared with similar patients with moderately severe CS. Further study of preventative strategies, including intensity of medical therapy, is warranted.

Internal Carotid Artery Occlusion

Objective:

To determine the incidence of recanalization of the occluded internal carotid artery (ICA) and establish its natural history.

Methods:

Patients with duplex-confirmed ICA occlusions were identified, and a subgroup offered repeat scanning. The antemortem condition and cause of death of patients who died were recorded.

Results:

Of 153 patients identified, 77 underwent follow-up at a median of 35 months (interquartile range [IQR]: 14-61).In all, 8 (10.3%) demonstrated recanalization at a median of 53 months (IQR: 35-114). Of 8, 7 underwent carotid endarterectomy with histopathological confirmation of recanalization. Of the 153 patients, 45 (29%) had further neurological events, and 38 (25%) were within the territory of the occluded ICA. In all, 76 patients died, and of the 53 with a confirmed cause of death, 12 (23%) were attributed to a cerebrovascular accident corresponding to the territory of the occluded artery.

Conclusion:

Recanalization of ICA occlusion is common and leads to significant neurological events. Duplex ultrasound follow-up appears mandatory.

Cerebral collateral circulation in carotid artery disease

Carotid artery disease is common and increases the risk of stroke. However, there is wide variability on the severity of clinical manifestations of carotid disease, ranging from asymptomatic to fatal stroke. The collateral circulation has been recognized as an important aspect of cerebral circulation affecting the risk of stroke as well as other features of stroke presentation, such as stroke patterns in patients with carotid artery disease. The cerebral circulation attempts to maintain constant cerebral perfusion despite changes in systemic conditions, due to its ability to autoregulate blood flow. In case that one of the major cerebral arteries is compromised by occlusive disease, the cerebral collateral circulation plays an important role in preserving cerebral perfusion through enhanced recruitment of blood flow. With the advent of techniques that allow rapid evaluation of cerebral perfusion, the collateral circulation of the brain and its effectiveness may also be evaluated, allowing for prompt assessment of patients with acute stroke due to involvement of the carotid artery, and risk stratification of patients with carotid stenosis in chronic stages. Understanding the cerebral collateral circulation provides a basis for the future development of new diagnostic tools, risk stratification, predictive models and new therapeutic modalities. In the present review we discuss basic aspects of the cerebral collateral circulation, diagnostic methods to assess collateral circulation, and implications in occlusive carotid artery disease.

Outcome analysis of carotid artery occlusion

The outcome of carotid artery occlusion was studied through the retrospective identification of 115 affected patients. The majority were white (77%) males (61%) with multiple atherogenic risk factors and suffering ipsilateral stroke (57%). Those patients presenting with stroke were not distinguished by demographic features, risk factors, lipid profile, medical regimen, or subsequent mortality when compared with those without. Overall, 36 patients (31%) required contralateral carotid endarterectomy (CEA), with one (2.8%) perioperative stroke, whereas 4 (3%) underwent ipsilateral external CEA without incident. With 81% follow-up (mean 3.9 years), the overall mortality of the group was 46%; the annualized risk of ipsilateral stroke was 1.6%. This study documents a significant risk of stroke and contralateral occlusive disease with ipsilateral carotid artery occlusion, which cannot be reliably predicted by clinical criteria. Duplex surveillance is valuable, but flow velocity measurements alone may be misleading. Surgical endarterectomy can be performed with an acceptable rate of perioperative stroke.

Natural history of carotid artery occlusion contralateral to carotid endarterectomy

BACKGROUND

The natural history of patients with carotid artery occlusion is controversial. A few studies have concluded that patients with internal carotid artery occlusion carry a high risk of neurologic events. None of these previously reported studies analyze the natural history of internal artery occlusion contralateral to carotid endarterectomy (CEA), except for a small series including a subset of patients from two randomized trials, the Asymptomatic Carotid Atherosclerosis Study and the North American Symptomatic Carotid Endarterectomy Trial. This study analyzes the natural history of patients with carotid artery occlusion contralateral to CEA, specifically assessing long-term neurologic events occurring in the hemisphere associated with the occluded carotid artery.

METHODS

Of the 599 CEAs in 544 patients that were included in two previously updated prospective studies, 63 patients had contralateral internal carotid artery occlusion, and their perioperative and long-term outcomes were evaluated. A Kaplan-Meier analysis was used to estimate the rate of freedom from late stroke occurring in the hemisphere ipsilateral to the occluded carotid artery. The stroke-free survival rate was also noted.

RESULTS

Mean follow-up was 58 months (range, 1 to 147 months). One perioperative stroke (1.6%) occurred, which was not in the cerebral hemisphere ipsilateral to the occluded carotid artery. Two late strokes (3.2%) and nine transient ischemic attacks (TIAs) (14.3%) occurred involving the hemisphere of the occluded carotid artery. There were also three late TIAs (4.8%) and no late strokes involving the hemisphere supplied by the operative site. There were a total of 14 late deaths. Fifteen patients had late > or =50% restenosis of the operative side. Six of these had neurologic events (TIA/stroke) involving the hemisphere of the occluded carotid artery, in contrast to five of 48 patients with no restenosis who had neurologic symptoms (P < .001). Freedom from late strokes in the hemisphere ipsilateral to the occluded carotid artery at 1, 3, 5, and 10 years was 98%, 96%, 96%, and 96%, respectively. The stroke-free survival rates at 1, 3, 5, and 10 years were 90%, 87%, 80%, and 59%, respectively.

CONCLUSIONS

The natural history of carotid artery occlusion contralateral to CEA is relatively benign. This may suggest a protective effect of carotid endarterectomy on the cerebral hemisphere ipsilateral to the carotid occlusion from late strokes.

Indications for cerebral revascularization for patients with atherosclerotic carotid occlusion

Patients with complete carotid occlusion and recent ischemic symptoms are at high risk for subsequent stroke, particularly those with evidence of severe hemodynamic impairment due to poor collateral flow. Treatment options for these patients include direct extracranial to intracranial arterial bypass, or interventions aimed at improving collateral sources of flow such as endarterectomy or angioplasty and stenting of the ipsilateral external carotid artery, the contralateral carotid artery, or the vertebral arteries. The evidence supporting the use of these procedures for patients with complete occlusion of the carotid artery will be the focus of this article. The use of physiologic imaging to select subgroups of patients at high risk due to hemodynamic factors will also be discussed.

Cerebral blood flow and oxygen metabolism in symptomatic internal carotid artery occlusion by atherosclerosis and by cervical dissection

Symptomatic internal carotid artery occlusion by atherosclerosis and by cervical dissection are distinct conditions with different long-term prognoses. The purpose of the present study is to investigate if regional cerebral blood flow and oxygen metabolism, after onset of stroke, differ between both conditions. Seventeen patients with symptomatic unilateral atherosclerotic internal carotid occlusion and 10 patients with symptomatic internal carotid occlusion due to cervical dissection were submitted to a positron emission tomographic (PET) study between 1 and 2 months after stroke onset. The steady state technique with 15O was used in order to determine regional cerebral blood flow, regional oxygen extraction fraction, and regional cerebral metabolic rate for oxygen in the infarct area, the peri-infarct zone, the remaining homolateral hemisphere, and the contralateral hemisphere. The results were compared between both patient's populations. The patients with cervical dissection were on average much younger than those with atherosclerotic occlusion, but neurological impairment on admission and disability at 3 months were comparable. Between both patient populations, no differences in rCBF, rOEF, and rCMRO2 could be demonstrated in the different regions of interest when the results were age-adjusted. Except for age-related changes, no differences in PET findings could be demonstrated between patients with symptomatic internal carotid occlusion caused by either atherosclerosis or cervical dissection.

Carotid surgery in acute symptomatic patients

OBJECTIVES

evaluation of urgent carotid artery surgery with new diagnostic techniques and changing surgical considerations at a university hospital.

DESIGN, MATERIAL AND METHODS

prospective monitoring and assessment of outcome in 67 patients who underwent urgent carotid surgery because of symptomatic extracranial carotid artery involvement. Patients were examined via the stroke unit: duplex sonography was mandatory for diagnosis of extracranial carotid artery disease, as was proof of an open middle cerebral artery (MCA). Assessment of intracerebral damage followed CT or MR imaging procedures. Perioperative and surgical management was standardized. Neurological impairment was assessed pre-, postoperatively and at follow-up using the Rankin scale. "Urgent" was defined as "immediate" after the final diagnostic step had been performed.

RESULTS

within a period of 26 months 67 symptomatic patients (58% stroke, 42% TIA) underwent urgent carotid surgery. Median time from admission to surgery was 2 days. In all but five cases flow through the ICA could technically be restored (93%). Thirty-day mortality was 3% and disease-related morbidity 13%. The one and two year survival rates were 92 and 90%, respectively. No ipsilateral recurrent stroke occurred during follow-up.

CONCLUSIONS

clinical decision-making based on stratified diagnostic workup by means of extra- and intracranial as well as intracerebral hemodynamics using new imaging techniques may select patients who will benefit more from urgent surgery than from conservative management.

Clinical outcome of patients with internal carotid artery occlusion: a prospective follow-up study

PURPOSE

We prospectively evaluated whether, and to what extent, different clinical presentations (symptomatic or asymptomatic) or the presence of atherosclerotic narrowing of the contralateral carotid system modifies the mortality rate and the incidence of nonfatal cerebrovascular events in patients with internal carotid artery (ICA) occlusion.

METHODS

A prospective cohort study was conducted in the Unit Care of Angiology at the University Hospital of Padua in Italy. Consecutive patients with ICA occlusion were eligible for the study. Between 1990 and 1991, 41 such patients were identified at our center. All patients were observed prospectively for a mean of 44.5 months, except for one patient who was lost to follow-up after 12 months. Patients with severe (ie, more than 75%) stenosis of the contralateral internal carotid artery were scheduled for thromboendarterectomy. ICA occlusion was objectively documented in all patients by using a combination of echo-color Doppler scanning and continuous-wave Doppler scanning (periorbital flow).

RESULTS

The overall mortality rate was 22.0% (95% CI, 10.6-37.6), and the stroke-related mortality rate was 7.3% (95% CI, 1.5-19.9). No differences in overall and stroke-related mortality rates were observed between asymptomatic and symptomatic patients. None of the patients experienced nonfatal cerebrovascular events.

CONCLUSION

ICA occlusion seems to represent a relatively benign condition, in both its symptomatic and asymptomatic presentation. The presence of an atherosclerotic stenosis less than 75% of the contralateral ICA does not seem to worsen the prognosis of this condition.

Colour-coded duplex sonography of preocclusive carotid stenoses

OBJECTIVE

The accuracy of colour-coded duplex sonography (CCDS) for differentiating preocclusive stenoses from occlusions of the internal carotid artery (ICA) is a crucial point in non-invasive quantification of atherosclerotic lesions prior to carotid endarterectomy.

METHODS

A total of 401 consecutive patients with CCDS followed by ICA arteriographies as gold standard was available for comparison. The entire number was divided into groups of <90%, 90-94%, preocclusive (95-99%) stenoses and occlusions. Sensitivity, specificity, and predictive value for distinguishing these groups were calculated using a contingency table.

RESULTS

With CCDS we found a sensitivity of 88% and a specificity of 99% in 43 preocclusive ?95% stenoses. Similar findings were seen in 31 occlusions of the ICA (SE 87%, SP 99%). CCDS accurately differentiates the subgroups of severe carotid obstructions (90-94%, ?95% and occluded) shown by a predictive accuracy of 97, 96 and 93%. Carotid endarterectomies were performed in two of three angiographically occluded but sonographically preocclusive arteries. Intraoperatively preocclusive ICAs were seen in both cases.

CONCLUSION

CCDS showed a high accuracy for differentiating preocclusive stenoses and occlusion of the ICA. Intraoperative findings indicated that angiography is not the absolute gold standard for preocclusive carotid disease in every case. Irregularities of the stenosis channel make it impossible to estimate the true area reduction in stenoses ?90%. The hemodynamic estimation of degree of stenosis by Doppler ultrasound may be closer to reality than angiographic measurement.

Stroke risk factors and development of collateral flow in carotid occlusive disease

BACKGROUND AND PURPOSE

Blood flow through collateral vessels compensates for reduced blood flow through stenotic or occluded extracranial carotid arteries. Previous studies have shown that extent of collateral flow influences likelihood of stroke and its outcome. Here we analyzed the relationship between stroke risk factors (hypertension, coronary artery disease, diabetes mellitus, tobacco smoking and hypercholesterolemia) and number of patent intracranial collaterals detected by transcranial Doppler ultrasonography.

SUBJECTS AND METHODS

We studied 182 patients with various degrees of angiography proven unilateral stenosis of the internal carotid artery. Contribution of the anterior and posterior communicating arteries to the perfusion of the cerebral hemisphere on the side of the stenosis or occlusion was evaluated by a series of compression tests performed during continuous insonation of the middle cerebral artery. The number of detected collateral vessels was correlated with analyzed stroke risk factors.

RESULTS

Subjects with stenosis more than 75% or occlusion of the internal carotid artery had a higher frequency of two major intracranial collateral vessels (P< or =0.01 and P< or =0.001, respectively). Hypertensive patients with stenosis more than 75% or total carotid occlusion were more likely to have only a single collateral vessel than patients without hypertension (P< or =0.01 and P< or =0.05, respectively). Other risk factors did not influence the patency of preformed collateral vessels.

CONCLUSIONS

Hypertension hindered the development of preformed intracranial collateral vessels in our patients with carotid occlusive disease.

Pseudo- and segmental occlusion of the internal carotid artery: a new classification, surgical treatment and results

OBJECTIVES

Occluded internal carotid arteries imply a high risk of ischaemic complications, but an "occluded" carotid artery is not always totally occluded. Pseudo- and segmental occlusions can be detected angiographically, and increasingly non-invasively, and include a variety of morphologic findings.

METHODS AND MATERIALS

128 patients with pseudo- or segmental occlusion were treated in a 13 year period. Three different types of pseudo- or segmental occlusion were identified. In most cases a subtotal stenosis (near-occlusion) at the carotid bifurcation is the underlying lesion (type I). In approximately 35% the internal carotid artery is totally occluded at the bifurcation, but collaterals prevent downstream occlusion (type II), or retrograde flow from the circle of Willis and ophthalmic artery preserves a patent petrous part and siphon (type III).

RESULTS

In 79% patency of the arteries could be restored. Three patients (2.3%) died perioperatively, nine (7%) developed ischaemic stroke (7 ipsilateral, 2 contralateral), one intracerebral haemorrhage. The combined stroke-mortality rate was 8.6%. During follow-up (41 +/- 29.9 months) four patients (4.5%) experienced a stroke (3 ipsilateral, 1 contralateral), one an intracranial (1.1%) haemorrhage and six transient ischaemic attacks (6.7%). The annual ipsilateral stroke rate was 0.9%, the cumulative patency rate of the entire series 78% after 73 months.

CONCLUSIONS

Although the surgical management carries an increased risk of complications (stroke, transient ischaemic attacks) compared to conventional carotid endarterectomy it is likely that the stroke risk can be reduced at least for symptomatic patients. Symptomatic internal carotid artery occlusion diagnosed non-invasively should be confirmed angiographically to exclude pseudo- or segmental occlusion.

Association of silent myocardial ischemia with new atherothrombotic brain infarction in older patients with extracranial internal or common carotid arterial disease with and without previous atherothrombotic brain infarction

OBJECTIVE

To correlate silent myocardial ischemia with the incidence of new atherothrombotic brain infarction (ABI) in older patients with 40 to 100% extracranial carotid arterial disease (ECAD) with and without prior ABI.

DESIGN

In a prospective study of 208 older patients with 40 to 100% ECAD diagnosed by carotid duplex ultrasonography, 24-hour ambulatory electrocardiograms were obtained to detect silent myocardial ischemia. At 42-month mean follow-up, silent myocardial ischemia was correlated with the incidence of new ABI in patients with and without prior ABI.

SETTING

A large long-term health care facility where 208 older patients with 40 to 100% ECAD and technically adequate 24-hour ambulatory electrocardiograms for detecting silent myocardial ischemia were studied.

PATIENTS

The 208 patients included 68 men and 140 women, mean age 81 +/- 8 years (range 60 to 100). One-hundred three (50%) of the patients had prior ABI.

MEASUREMENTS AND MAIN RESULTS

Sixty-nine (33%) of the 208 patients had silent myocardial ischemia. Mean follow-up was 42 +/- 25 months (range 3 to 101 months). At follow-up, the incidence of new ABI was 64% in patients with prior ABI and 32% in patients with no prior ABI (P < .0001). At follow-up, the incidence of new ABI was 65% in patients with silent ischemia and 40% in patients with no silent ischemia (P = .0005). The multivariate Cox regression model showed that patients with prior ABI have a 2.5 times higher chance of developing new ABI than those without prior ABI after controlling other prognostic variables. Patients with silent ischemia have a 2.1 times higher probability of developing new ABI than those without silent ischemia after controlling other prognostic variables.

CONCLUSIONS

Prior ABI and silent ischemia are independent risk factors for the development of new ABI in patients with 40 to 100% ECAD. This probably reflects that silent ischemia is a marker for more advanced or more significant atherosclerotic disease rather than a causal factor for ABI.

Prevalence and outcome of symptomatic carotid lesions in young adults. National Research Council Study Group

OBJECTIVE

To estimate the prevalence and outcome of symptomatic internal carotid artery lesions in young adults.

DESIGN

Multicentre hospital based observational study with five year follow up.

SETTING

Seven neurological departments in northern and central Italy.

SUBJECTS

240 patients (115 men) aged 15-44 with a recent transient ischaemic attack or stroke in the carotid territory.

MAIN OUTCOME MEASURES

(a) Prevalence of symptomatic internal carotid artery stenosis or occlusion detected by continuous wave Doppler ultrasonography at entry; (b) incidence rates of cerebral, cardiac, and non-vascular death; non-fatal stroke; and non-fatal myocardial infarction.

RESULTS

Carotid stenoses of 50-99% and occlusions were found in 38 patients (15.8%). Both conditions were significantly more frequent in patients aged over 35 and in those with hypertension, diabetes mellitus, and stroke at entry. The standardised mortality ratio at five years was 10.5 (95% confidence interval 5.0 to 19.3). Survival of patients with stenoses of 0-49% and occlusions was significantly better than that of patients with stenoses of 50-99%. Carotid stenosis of 50-99% was an independent predictor of death (hazard ratio 7.9; 95% confidence interval 2.2 to 29) and non-fatal stroke (hazard ratio 7.4; 1.5 to 37.4).

CONCLUSIONS

The prevalence of carotid stenosis or occlusion in young adults after a cerebrovascular event is low. Though patients with high grade symptomatic carotid stenosis are at risk of non-fetal and fetal events, patients with internal artery occlusion apparently have a benign prognosis.

Compressions of carotid and vertebral arteries in assessment of intracranial collateral flow: correlation between angiography and transcranial Doppler ultrasonography

The authors examined 61 subjects with carotid angiography and 50 with vertebral angiography. Angiograms were evaluated for collateral flow through the ophthalmic, anterior communicating, and posterior communicating arteries. The authors evaluated the patency of collateral vessels directly using transcranial Doppler ultrasonography; they made indirect detection after the compression of carotid and vertebral arteries while monitoring flow velocities in the middle cerebral artery. They established criteria for the hemodynamic significance of tested collateral vessels. A combination of carotid compressions and transcranial Doppler ultrasonography detected the patency of the ophthalmic and anterior communicating arteries with a specificity and sensitivity of 1.00. Examination of the posterior communicating artery had a sensitivity of 0.97 and specificity of 0.98. Indirect evaluation of collateral vessels can not only detect their presence but also establish their hemodynamic significance with high accuracy.

Natural history of patients with chronic occlusion of the internal carotid artery

Although 3% of the elderly population may have asymptomatic unilateral internal carotid artery occlusion (ICAO), between 10% and 20% of patients with initial stroke in the carotid territory have appropriate ipsilateral extracranial ICAO. In the latter instance, it is often difficult to establish whether ICAO is (a) an acute thrombotic process on an underlying atheromatous stenosis; (b) an acute embolic ICAO (from heart or aorta); or (c) an old ICAO that was previously asymptomatic. Intracranial studies show that the first stroke ipsilateral to ICAO is usually associated with occlusions distal to ICAO, which suggest artery-to-artery embolism. On the other hand, the follow-up of stroke patients with ICAO shows that delayed cerebral infarction distal to the established ICAO often involves watershed areas and may correspond to hemodynamic disturbances. Because the international extracranial/intracranial arterial bypass study did not show any surgical benefit, current management is mainly directed to stabilization of associated causes of hemodynamic failure (hypotension, bradycardia, etc.). Attempts to find subgroups that may benefit from bypass surgery are still ongoing. However, the prognosis of these patients is negatively influenced by a particularly high risk of cardiac death.

Outcome of progression from carotid stenosis to occlusion

The incidence of symptoms at the moment the internal carotid artery (ICA) occludes was assessed in 33 patients. Duplex scanning was performed to determine the progression from stenosis to ICA occlusion. There were 24 patients with a primary stenosis and nine with a restenosis after a carotid endarterectomy. In 18% (6/33) the occlusion was accompanied by a stroke. A transient ischaemic attack (TIA) was seen in 12% (4/33) of patients and 70% (23/33) remained asymptomatic. There was no difference in stroke rate between patients with primary stenosis (4/24:17%) and those with restenosis (2/9:22%). The mean follow-up was 3.2 years and the mean elapse time to occlusion in patients with a stroke was 20 months, with a TIA, 32 months, and in asymptomatic patients, 44 months. It was also shown that a stenosis of greater than 80% diameter reduction had a faster progression (mean 1 year) than a less than 80% stenosis (mean 3.5 years) (p = 0.04). Patients with a stenosis greater than 80% tended to have a higher incidence (40%:2/5) of stroke at the time of occlusion than patients with a stenosis less than 80% (14%:2/28). The results show that an occlusion of the ICA is accompanied by a stroke in 18% of the cases and that patients with a rapid progression and/or greater than 80% stenosis are at high risk. From this point of view a carotid endarterectomy should be considered in order to prevent an occlusion of the ICA and a high risk of stroke.

Prognosis of asymptomatic carotid occlusion

Ninety-four asymptomatic patients with internal carotid artery occlusion were followed for a mean of 44 months, 16% suffered strokes and 11.7% reported transient ischemic attacks (TIA). The annual stroke and TIA rates were 4.4% and 3.2%, respectively, the annual mortality was 11.3%. In 27 asymptomatic patients progression of extracranial arterial disease to occlusion was observed: 7.4% of these patients suffered from stroke and 18.5% reported TIA's during that period. Thus the annual stroke rate was lower (1.9%) but the TIA rate higher (4.7%) than post-occlusive rates. These data reflect an increase risk in patients with progressive high-degree carotid stenosis which continues after occlusion. This may favour carotid endarterectomy for selected patients in the pre-occlusive state because medical treatment has not been shown to prevent progression of stenosis to occlusion.

Safety and long-term benefit of carotid endarterectomy in the asymptomatic patient

In order to determine the safety and long-term salutary effects of carotid endarterectomy in the asymptomatic patient, we retrospectively reviewed all asymptomatic patients who underwent carotid endarterectomy from 1980 through 1986. There were 60 carotid endarterectomies performed in 54 patients, 53 men and one woman. The mean age was 64 years. Arteriography revealed a high grade stenosis of 70% or greater in 46 carotid arteries (77%), ulceration in five (8%), and both in nine (15%). Risk factors included coronary artery disease in 60% of patients, smoking in 87%, hypertension in 67%, and diabetes in 22%. Perioperative morbidity included three cranial nerve injuries, one myocardial infarction and one contralateral stroke. There were no deaths. Mean follow-up was 47 months with only two patients being lost to follow-up. During follow-up three patients suffered ipsilateral transient ischemic attacks without recurrent carotid stenosis and one patient had a transient ischemic attack secondary to contralateral carotid occlusion. There was one ipsilateral stroke occurring two years after operation secondary to restenosis that required reoperation and four late contralateral strokes. Ten patients died in the follow-up period. Causes of death were stroke (1), cardiac (4), malignancy (2), pulmonary (2), and unknown (1). All surviving patients were evaluated by duplex scan at a mean interval following surgery of 47 months. Restenosis of endarterectomized arteries was seen at the following rates: less than 50% in 41 (87%); 50-75% in four (8.5%); 80% in one (2%); and 90% in one (2%). Life table analysis revealed a 98% ipsilateral stroke-free rate at five and eight years.(ABSTRACT TRUNCATED AT 250 WORDS)

Duplex ultrasound in carotid artery disease: some diagnostic considerations

Loss of pressure across a stenosis depends on the geometry of that obstruction, but flow only depends on geometry when both perfusion pressure and peripheral resistance are constant. As cerebrovascular resistance is generally low then flow over a stenosis will be dominated by stenotic resistance. A relatively modest reduction in systolic perfusion pressure will produce a large increase in stenotic resistance. Evaluation of a 'haemodynamically significant' or 'critical' or 'dynamic' stenosis should include consideration of variations in cardiac function and blood pressure as well as local vascular dynamics. Examination of the ultrasound image characteristics of the arterial lesion gives additional structural information of the contents and surface of the lesion and any movement relative to the vessel wall. This may give guidance in separating clinically stable from unstable lesions, and also in following progression or regression of disease. The physical forces which are applied to some lesions may cause the release of material from the substance of the lesion into the arterial lumen or cause damage resulting in progression of the lesion itself.

Long-term follow-up of carotid disease: clinical and ultrasound aspects

Various non-invasive techniques were used to study clinical and ultrasound aspects of extracranial arterial disease. cw Doppler was used prospectively to study the natural history of asymptomatic extracranial arterial disease (greater than 50% carotid stenosis, subclavian steal phenomena) in 401 patients. Whereas the cumulative death rate was high (44%) at 8 years, the stroke rate was low (6%). Progression of the vascular processes during follow-up correlated with later cerebrovascular events. Transcranial PW Doppler was used to study the intracranial collaterlisation in 151 asymptomatic patients with significant extracranial lesions. The majority of patients showed excellent collateralisation. The natural history of non-stenotic plaques (less than 30% carotid stenosis) was studied by means of high-resolution (10 MHz) duplex system analysis. Whilst most plaques remained constant during the subsequent follow-up period progression was seen in 24% and regression in 10%.

Recognising stroke prone patients with a poor collateral circulation

The prognosis in carotid disease is extremely variable and is influenced by the availability of collateral circulation. This study investigates the possibility of recognising patients with a poor collateral potential by using non-invasive tests. Preoperative OPG and EEG were compared with intraoperative EEG during test clamping in 208 carotid endarterectomies. Clamping ischaemia occurred in 29 patients (14%). Preoperative EEG had a sensitivity of 62% and a specificity of 82%. OPG showed a sensitivity of 96% and a specificity of 54%. Combined OPG and EEG resulted in a sensitivity of 93% and a specificity of 73%. Both tests are safe and easy to perform and interpret. These techniques can be used to identify those patients with carotid stenosis who have an increased risk of stroke due to a poor collateral circulation and may help to refine the indications for carotid endarterectomy.