Carotid artery stenting in patients with high-risk anatomy for carotid endarterectomy

Anatomical Considerations for Endovascular Intervention for Extracranial Carotid Disease: A Review of the Literature and Recommended Guidelines

Patient selection for endovascular intervention in extracranial carotid disease is centered on vascular anatomy. We review anatomical considerations for non-traumatic disease and offer guidelines in patient selection and management. We conducted a systematic literature review without meta-analysis for studies involving anatomical considerations in extracranial carotid intervention for non-traumatic disease. Anatomical considerations discussed included aortic arch variants, degree of vessel stenosis, angulation, tortuosity, and anomalous origins, and atheromatous plaque morphology, composition, and location. Available literature suggests that anatomical risks of morbidity are largely secondary to increased procedural times and difficulties in intervention system delivery. We recommend the prioritization of endovascular techniques on an individual basis in cases where accessible systems and surgeon familiarity provide an acceptable likelihood of rapid access and device deployment.

Anatomical Considerations on Surgical Anatomy of the Carotid Bifurcation

Surgical anatomy of carotid bifurcation is of unique importance for numerous medical specialties. Despite extensive research, many aspects such as precise height of carotid bifurcation, micrometric values of carotid arteries and their branches as their diameter, length, and degree of tortuosity, and variations of proximal external carotid artery branches are undetermined. Furthermore carotid bifurcation is involved in many pathologic processes, atheromatous disease being the commonest. Carotid atheromatous disease is a major predisposing factor for disabling and possibly fatal strokes with geometry of carotid bifurcation playing an important role in its natural history. Consequently detailed knowledge of various anatomic parameters is of paramount importance not only for understanding of the disease but also for design of surgical treatment, especially selection between carotid endarterectomy and carotid stenting. Carotid bifurcation paragangliomas constitute unique tumors with diagnostic accuracy, treatment design, and success of operative intervention dependent on precise knowledge of anatomy. Considering those, it becomes clear that selection and application of proper surgical therapy should consider anatomical details. Further research might ameliorate available treatment options or even lead to innovative ones.

Percutaneous transluminal renal angioplasty remarkably improved severe hypertension and renal function in a patient with renal artery stenosis and postrenal kidney failure

A 69-year-old man was admitted to our hospital with severe hypertension and rapidly worsening renal function. He presented with a 10-year history of chronic renal failure caused by bilateral ureteral obstruction due to retroperitoneal fibrosis. Magnetic resonance angiography and Doppler ultrasonography suggested severe right renal artery stenosis (RAS). Renal angiography revealed 99% stenosis at the ostium of the right renal artery. We performed percutaneous transluminal renal angioplasty (PTRA) with the support of intravascular ultrasound to decrease the amount of contrast agent needed. In addition, to prevent distal atheroembolism, a distal protection device was used. The procedure was completed without any adverse effects. After PTRA, renal function and blood pressure improved remarkably and remained stable for one year. PTRA for RAS remains controversial, especially in patients with renal insufficiency. Use of new devices should be considered to decrease catheterization-related adverse effects.

Ischemic preconditioning during the use of the PercuSurge occlusion balloon for carotid angioplasty and stenting

Ischemic preconditioning (IP) uses transient ischemia to render tissues tolerant to subsequent, prolonged ischemia. This study sought to evaluate factors that contributed to the development of cerebral ischemia during PercuSurge balloon (Medtronic, Santa Rosa, CA) occlusion in patients undergoing carotid angioplasty and stenting (CAS). The PercuSurge occlusion balloon was used in 43 of 165 patients treated with CAS for high-grade stenosis; 20% were symptomatic. Symptoms of cerebral hypoperfusion during temporary occlusion of the internal carotid artery occurred in 10 of 43 patients and included dysarthria, agitation, decreased level of consciousness, and focal hemispheric deficit. The development of neurologic symptoms after initial PercuSurge balloon inflation and occluded internal carotid artery flow was associated with a decrease in the mean Glasgow Coma Scale (GCS) from 15 to 10 (range 9-14); the GCS returned to normal after occlusion balloon deflation. The mean time to spontaneous recovery of full neurologic function was 8 minutes (range 4-15 minutes). The mean subsequent procedure duration was 11.9 minutes (range 6-21 minutes). No recurrence of neurologic symptoms occurred when the occlusion balloon was reinflated. All 10 patients underwent successful CAS without occlusion, dissection, cerebrovascular accident, or death. Ischemic preconditioning can be used to enable CAS with embolic protection in patients who cannot tolerate initial interruption of antegrade cerebral perfusion by PercuSurge occlusion.

Renovascular hypertension

Renal artery disease is the most common cause of potentially curable secondary hypertension, with atherosclerosis as the major cause of renal artery stenosis. Fibromuscular dysplasia is a less common cause of renal artery stenosis and is most frequently observed in premenopausal women. Renal artery stenosis is likely to be underappreciated and is more common in patients with other vascular disease (e.g., coronary or peripheral arterial disease). The diagnosis of renal artery stenosis requires a high clinical index of suspicion as well as an appropriate imaging strategy, with currently effective diagnostic modalities including magnetic resonance imaging, computed tomography and renal artery duplex ultrasonography. The current treatment of choice for atherosclerotic renal artery stenosis is balloon angioplasty and secondary stenting, whereas angioplasty alone is the treatment for renal artery stenosis secondary to fibromuscular dysplasia. Expected outcomes following revascularization include improved blood pressure control and possibly renal preservation. Ongoing studies will hopefully identify patient characteristics that will achieve the most benefit from percutaneous revascularization as well as the impact of percutaneous revascularization with drug-eluting stents and embolic protection devices.

Cerebral ischemia associated with PercuSurge balloon occlusion balloon during carotid stenting: Incidence and possible mechanisms

BACKGROUND

Interruption of antegrade cerebral perfusion results in transient neurologic intolerance in some patients undergoing carotid angioplasty and stenting (CAS). This study sought to evaluate factors that contributed to the development of cerebral ischemia during PercuSurge balloon occlusion and techniques used to allow successful completion of the CAS procedure.

METHODS

The PercuSurge occlusion balloon was used in 43 of 165 patients treated with CAS for high-grade stenosis (mean stenosis, 90%). All 43 patients were at increased risk for endarterectomy (7 restenosis, 3 irradiation, 3 contralateral occlusion, and 30 Goldman class II-III); 20% were symptomatic. Symptoms of cerebral hypoperfusion during temporary occlusion of the internal carotid artery occurred in 10 of 43 and included dysarthria (7/10), agitation (6/10), decreased level of consciousness (5/10), and focal hemispheric deficit (3/10). An incomplete circle of Willis or contralateral carotid artery occlusion, or both, was present in 8 of 10 patients. Symptoms resulting from PercuSurge balloon occlusion were managed by balloon deflation with or without evacuation of blood from the internal carotid artery using the Export catheter. All symptoms resolved completely without deficit after deflation of the occlusion balloon.

RESULTS

The development of neurologic symptoms after initial PercuSurge balloon inflation and occluded internal carotid artery flow was associated with a decrease in the mean Glasgow Coma Scale (GCS) from 15 to 10 (range, 9 to 14); the GCS returned to normal after occlusion balloon deflation and remained normal during subsequent reinflation. The mean time to spontaneous recovery of full neurologic function was 8 minutes (range, 4 to 15 minutes). No thrombotic or embolic events were present on cerebral angiography or computed tomography scan. Balloon reinflation was performed after a mean reperfusion interval of 10 minutes after full neurologic recovery (range, 4 to 20 minutes). The mean subsequent procedure duration was 11.9 minutes (range, 6 to 21 minutes). No recurrence of neurologic symptoms occurred when the occlusion balloon was reinflated. All 10 patients underwent successful CAS without occlusion, dissection, cerebrovascular accident, or death.

CONCLUSION

Several factors may contribute to the development of neurologic intolerance during CAS with balloon occlusion. Elucidation of the protective cellular mechanisms that invoke ischemic tolerance after the initial transient ischemic event may enable CAS with embolic protection in patients who cannot tolerate initial interruption of antegrade cerebral perfusion.

Continuity in the Treatment of Carotid Artery Disease: Results of a Carotid Stenting Program Initiated by Vascular Surgeons

The treatment of carotid artery stenosis currently constitutes a major component of vascular surgical practice. Carotid angioplasty and stenting (CAS), however, is mainly performed by nonvascular surgeon interventionalists with cerebral protection devices available only through investigational protocols. This study reports the initial results of a CAS program initiated and performed by vascular surgeons using commercially available cerebral protection devices. Fifty-seven patients were enrolled in the study over a 14-month period. All patients were at high risk for conventional endarterectomy (7 resentosis, 4 irradiation, and 46 medically high-risk ASA III). Mean age was 75.7 years (range, 45-93 years). High-grade stenosis of the carotid artery was present in all cases (mean stenosis, 85%; range, 80-99%). Twenty-four percent of patients were symptomatic. Cerebral protection was performed with an occlusion balloon-wire in 32 cases and with a filter-wire device in 24; no cerebral protection was used in 1 patient with restenosis after endarterectomy. Initially in the study, atropine was administered selectively for the development of bradycardia. Currently atropine is administered routinely prior to the initial balloon angioplasty of the carotid bulb. Clopidogrel (75 mg/day) was administered for 5 days prior to CAS and for 30 days after CAS. All 57 patients underwent successful dilatation of their carotid stenoses without occlusion or dissection. Ten of 32 patients in whom balloon occlusion was used for cerebral protection exhibited transient evidence of cerebral ischemia during protection balloon occlusion. These symptoms resolved completely without permanent neurological deficit in all cases. Development of bradycardia with a heart rate <50 bpm was significantly reduced by routine administration of atropine prior to the initial dilatation within the carotid bulb (p = 0.01). Mean hospital length of stay was 1.33 days (range, 1-5 days). There were two periprocedure myocardial infarctions, two postprocedure transient ischemic attacks, and one reversible ischemic neurologic deficit. There was no 30-day mortality. There have been no instances of hemodynamically significant restenosis during a mean follow-up period of 5.4 months. From these results we have concluded that CAS can be performed effectively and safely using commercially available cerebral protection devices. A program initiated and performed exclusively by vascular surgeons is effective and should be the standard model used in the endovascular treatment of carotid artery stenosis.

Carotid endarterectomy at the millennium: what interventional therapy must match

OBJECTIVES

Carotid endarterectomy (CEA) is supported by level 1 evidence as the standard treatment of severe carotid stenosis in both symptomatic and asymptomatic patients. As interventional techniques are emerging for treatment of this disease, this study was undertaken to provide a contemporary surgical standard for comparison to carotid stenting.

PATIENTS AND METHODS

During the interval 1989 to 1999, 2236 isolated CEAs were performed on 1897 patients (62% male, 36% symptomatic, 4.6% reoperative procedures). Study endpoints included perioperative events, patient survival, late incidence of stroke, anatomic durability of CEA, and resource utilization changes during the study. Variables associated with complications, long-term and stroke free survival, restenosis, and resource utilization were analyzed by univariate and multivariate analysis.

RESULTS

Perioperative complications occurred in 5.5% of CEA procedures, including any stroke/death (1.4%), neck hematoma (1.7%), cardiac complications (0.5%), and cranial nerve injury (0.4%). Actuarial survival at 5 and 10 years was 72.4% (95% confidence interval [CI] 69.3-73.5) and 44.7% (95% CI 41.7-47.9) respectively, with coronary artery disease (P < 0.0018), chronic obstructive pulmonary disease (P < 0.00018) and diabetes mellitus (P < 0.0011) correlating with decreased longevity. The age- and sex-adjusted incidence of any stroke during follow-up was reduced by 22% (upper 0.35, lower 0.08) of predicted with the patient classification of hyperlipidemia (P < 0.0045) as the only protective factor. Analysis of CEA anatomic durability during a median follow-up period of 5.9 years identified a 7.7% failure rate (severe restenosis/occlusion, 4.5%; or reoperative CEA, 3.2%) with elevated serum cholesterol (P < 0.017) correlating with early restenosis. Resource utilization diminished (first versus last 2-year interval periods) for average hospital length of stay from 10.3 +/- 1.5 days to 4.3 +/- 0.7 days (P < 0.01) and preoperative contrast angiography from 87% +/- 1.4% to 10.3% +/- 4%.

CONCLUSIONS

These data delineate the safety, durability, and effectiveness in long-term stroke prevention of CEA. They provide a standard to which emerging catheter-based therapies for carotid stenosis should be compared.

Durability of carotid endarterectomy for treatment of symptomatic and asymptomatic stenoses

PURPOSE

Although many studies have well established that carotid endarterectomy (CEA) is beneficial in selected patients with severe carotid disease, only a few large studies have focused on the durability of the surgical procedure. Carotid artery angioplasty and stenting (CAS) has recently been proposed as a potential alternative to CEA. We analyzed the incidence of late occlusion and recurrent stenosis after CEA.

METHODS

Over 13 years 1000 patients underwent 1150 CEA procedures to treat symptomatic and asymptomatic high-grade carotid stenosis. CEA procedures involving either traditional CEA with patching (n = 302) or eversion CEA (n = 848) were all performed by the same surgeon, with patients under deep general anesthesia and cerebral protection involving continuous electroencephalographic monitoring for selective shunting. All patients underwent postoperative duplex ultrasound scanning and clinical follow-up at 1, 6, and 12 months, and yearly thereafter. New neurologic events, late occlusions, and recurrent stenoses 50% or greater were recorded. Complete follow-up (mean, 6.2 years; range, 6-156 months) was obtained in 95% of patients (949 of 1000), for an overall average of 95% of procedures (1092 of 1150). Survival analysis was performed with the Kaplan-Meier life table method.

RESULTS

Perioperative (30-day) mortality rate was 0.3% (3 of 1000), and stroke rate was 0.9% (11 of 1150), with a combined mortality and stroke rate of 1.2%. The incidence of late occlusion and recurrent stenosis 70% or greater was 0.6% and 0.5%, respectively, with a combined occlusion and restenosis rate of 1.1%. Kaplan-Meier analysis showed that the rate of freedom from occlusion, restenosis 70% or greater, and combined occlusion and restenosis 70% or greater at 12 years was 99,4%, 99.5%, and 98.8%, respectively. Occlusion and restenosis developed asymptomatically.

CONCLUSIONS

CEA is a low-risk procedure for treating severe symptomatic and asymptomatic carotid disease, with excellent long-term durability. Proponents of CAS should bear this in mind before considering CAS as a routine alternative to CEA.

Octogenarians with contralateral carotid artery occlusion: a cohort at higher risk for carotid endarterectomy?

PURPOSE

Carotid angioplasty and stenting has been proposed as a treatment option for carotid occlusive disease in patients at high risk, including those 80 years of age or older or with contralateral carotid occlusion. We analyzed 30-day mortality and stroke risk rates of carotid endarterectomy (CEA) in patients aged 80 years or older with concurrent carotid occlusive disease.

METHODS

From a retrospective review of 1000 patients undergoing 1150 CEA procedures to treat symptomatic and asymptomatic carotid lesions over 13 years, we identified 54 patients (5.4%) aged 80 years or older with concurrent contralateral carotid occlusion. These patients were compared with 38 patients (3.8%) aged 80 years or older with normal or diseased patent contralateral carotid artery and 81 patients (8.1%) younger than 80 years with contralateral carotid occlusion. All CEA procedures involved either standard CEA with patching or eversion CEA, and were performed by the same surgeon, with the patients under deep general anesthesia and cerebral protection involving continuous perioperative electroencephalographic monitoring for selective shunting. Shunting criteria were based exclusively on electroencephalographic abnormalities consistent with cerebral ischemia.

RESULTS

The 30-day mortality and stroke rate in patients aged 80 years or older with concurrent contralateral carotid occlusion was zero.

CONCLUSIONS

The concept of high-risk CEA needs to be revisited. Patients with two of the criteria considered high risk in the medical literature, that is, age 80 years or older and contralateral carotid occlusion, can undergo CEA with no greater risks or complications. Until prospective randomized trials designed to evaluate the role of carotid angioplasty and stenting have been completed, CEA should remain the standard treatment in such patients.

Arterial remodeling and hemodynamics in carotid stents: a prospective duplex ultrasound study over 2 years

OBJECTIVE

This study was undertaken to study negative and positive arterial remodeling processes within self-expanding carotid stents, their interaction, and the resulting changes in hemodynamics over 2 years, with duplex ultrasound scanning.

SUBJECTS AND METHODS

One hundred twelve consecutive patients with 121 successfully stented carotid arteries were examined with color-coded duplex ultrasound scanning the day after the stent procedure and at 3, 6, 12, and 24 months of follow-up. The stent diameters at the proximal, middle, and distal regions, and the maximal neointimal thickness (B-mode) and hemodynamic parameters were recorded. Pre-interventional plaques were assigned to three types: soft, fibrous, and largely calcified.

RESULTS

The diameters of the self-expanding stents steadily increased over 2 years (positive arterial remodeling), from (mean +/- SD) 5.80 +/- 0.89 mm to 6.77 +/- 0.98 mm in the proximal stent area, from 3.51 +/- 0.76 mm to 4.92 +/- 0.89 mm in the middle stent area, and from 3.7 +/- 0.5 mm to 4.68 +/- 0.61 mm in the distal stent area (P<.001). Stent expansion was most marked in the middle stent area, depending on the type of pre-interventional plaque. The extent in stent expansion was more in soft than in fibrous and calcified plaques (P<.001). Neointimal thickness increased up to 12 months, and stabilized thereafter. The mean (+/- SD) neointimal thickness at 3, 6, 12, and 24 months was 0.61 +/- 0.28 mm, 0.97 +/- 0.39 mm, 1.06 +/- 0.36 mm, and 1.12 +/- 0.38 mm, respectively. These complex interactions resulted in the dominance of negative remodeling secondary to neointimal proliferation, with an increased flow ratio during the first year, from 1.16 +/- 0.37 at day 1 to 1.23 +/- 0.46 at 3 months, 1.67 +/- 1.37 at 6 months, and 1.57 +/- 0.70 at 12 months (P<.001), followed by a tendency to decrease as a result of stent expansion thereafter (flow ratio at 24 months, 1.49 +/- 0.70). Two of 121 stents (1.6%) had recurrent stenosis that required a secondary procedure.

CONCLUSIONS

Neointimal proliferation or negative arterial remodeling prevails up to 12 months, and may give rise to rare stent recurrent stenosis. Stent expansion reduces this effect in the first year, and dominates in the second year. This might contribute to the good mid-term outcome of carotid stenting. Poor stent expansion in heavily calcified plaques calls for primary surgical management.

Neointimal proliferation within carotid stents is more pronounced in diabetic patients with initial poor glycaemic state

AIMS/HYPOTHESIS

We studied the influence of initial hyperglycaemia on neointimal proliferation within carotid Wallstents.

METHODS

A total of 112 patients were followed by duplex sonography after carotid stenting for 24 months. Patients were assigned to three groups: non-diabetic subjects (group A) and diabetic patients, who were assigned according to their baseline HbA(1)c values, to group B1(HbA(1)c<or=6.5%) or group B2 (HbA(1)c>6.5%).

RESULTS

At baseline the groups did not differ with respect to other vascular risk factors and residual stenosis on angiograms. The maximal thickness of the layer between the stent and the perfused lumen was measured at the duplex follow-ups. At 3 months the typical ultrasonic structure of the neointima was clearly discernible. From this point on, group B2 differed significantly ( p<0.001) compared with B1 and A with respect to the maximal thickness of neointima and the time course of its ingrowth: group A vs B1 vs B2 was 0.51+/-0.39 vs 0.52+/-0.33 vs 0.56+/-0.35 at 3 months, 0.91+/-0.27 vs 0.90+/-0.38 vs 1.14+/-0.48 at 6 months, 1.02+/-0.24 vs 0.97+/-0.34 vs 1.21+/-0.44 at 12 months and 1.09+/-0.23 vs 1.10+/-0.31 vs 1.23+/-0.37 at 24 months.

CONCLUSION/INTERPRETATION

Initial hyperglycaemia seems to be a predictor of more pronounced neointimal proliferation after carotid stenting independent of diabetes. As intimal hyperplasia is known to be responsible for stent restenosis, strict optimisation of the hyperglycaemic state should be aimed at before elective carotid artery stenting.

Healing of carotid stents: a prospective duplex ultrasound study

PURPOSE

To study the dynamics of carotid stent healing over a 2-year period using duplex ultrasound imaging.

METHODS

One hundred twelve patients with 121 successfully stented carotid arteries were examined with color-coded duplex ultrasound the day after the stent procedure and at 1, 3, 6, 12, and 24 months in follow-up. The maximal thickness and echogenicity of the layer between the stent and the perfused lumen (SPL) were evaluated. Echogenicity was classified as echogenic if the SPL layer was clearly detected in B mode and echolucent if the SPL layer was barely visible in B mode, its border defined by assistance of color-coded flow.

RESULTS

At day 1, an echolucent SPL layer with a median thickness of 0.7 mm was interpreted as a thrombotic layer, which decreased at 1 month to practically zero (i.e., not detectable). In follow-up, increases in thickness (mainly up to 6 months) and echogenicity (up to 12 months) of the SPL layer were interpreted as neointimal ingrowth. At 3, 6, and 12 months, the median maximal thickness of the SPL layer was 0.5 mm, 0.9 mm, and 1.0 mm, respectively, whereas the percentage of patients with an echogenic SPL layer was 27% (32/119), 56% (66/117), and 95% (105/110), respectively, at the same time intervals. No further change was observed at the 24-month examination.

CONCLUSIONS

Three phases of carotid stent incorporation are defined: (1) an early unstable period soon after stent placement with an echolucent (thrombotic) SPL layer, (2) a moderately unstable phase with ingrowing neointima (1-12 months), and (3) a stable phase from the second year on. These data may indicate the need for different intensities of therapy and surveillance intervals.

Efficacy of a nitinol filter device in the prevention of embolic events during carotid interventions

PURPOSE

To evaluate the feasibility, safety, and efficacy of the TRAP Vascular Filtration System (VFS) during carotid interventions as a deterrent to embolic complications.

METHODS

Thirty-one consecutive patients (18 men; mean age 72 +/- 8 years) gave informed consent to undergo elective percutaneous angioplasty and stenting of the extracranial carotid artery protected by the TRAP VFS, a nitinol basket filter system.

RESULTS

The TRAP VFS was delivered and retrieved safely in all patients; procedural success for carotid stenting was 100%. In 3 (9.7%) cases, the filters were positioned after lesion predilation. Nearly half (13, 41.9%) of the retrieved filters contained visible plaque debris that histology identified as cholesterol crystals, fibrin material, atheromatous plaque, and macrophage foam cells. There were no symptomatic major or minor neurological complications encountered in this cohort during hospitalization.

CONCLUSIONS

Our data indicate that percutaneous dilation and stenting of the carotid artery protected by TRAP VFS appears to be feasible, safe, and effective in preventing cerebral embolization.

Percutaneous access and closure of femoral artery access sites associated with endoluminal repair of abdominal aortic aneurysms

PURPOSE

To report longer follow-up and further experience using the Prostar XL Percutaneous Vascular Surgery (PVS) device for access and closure of large bore femoral artery access sites during endovascular repair of abdominal aortic aneurysms (AAAs).

METHODS

One hundred forty-four patients (128 men; mean age 72 years, range 56-89) undergoing endovascular AAA repair had percutaneous access and closure of their 16-F femoral artery access sites using a 10-F PVS device. The first 54 patients were enrolled in the phase III trial of the AneuRx stent-graft for AAA treatment.

RESULTS

The femoral artery access site was successfully closed in 136 (94.4%) patients, with only 8 patients in whom adequate hemostasis could not be obtained. One-month follow-up was available in 144 patients, 6-month in 100, and 1-year in 59. No groin or lower extremity complications have been observed in any patient who had successful closure of the femoral artery access site.

CONCLUSIONS

Large-bore femoral artery access sites can be percutaneously repaired using this device, which minimizes the invasiveness of the endograft procedure.

The ICAROS registry of carotid artery stenting. Imaging in Carotid Angioplasties and Risk of Stroke

ICAROS (Imaging in Carotid Angioplasties and Risk Of Stroke) is a multicenter international registry of carotid artery stenting designed to determine the criteria for identifying patients at higher or lower risk of periprocedural stroke and restenosis at 1 year. The aim of the registry is to improve patient selection and consequently reduce the risk of cerebral embolization during carotid stenting. The registry is open to all interventionists performing carotid stenting, and the participants are free to apply their own endovascular techniques and devices, including cerebral protection mechanisms. All cerebral ischemic events following the procedure will be reported. Follow-up surveillance to 1 year will include periodic duplex scanning and neurological examinations. Echographic plaque images will be standardized for comparison, processed for echodensity, and analyzed by computer at the Registry Center. Correlation will be investigated between the echographic index (gray-scale median) and the risk of embolism and outcome of carotid stenting.