Duplex ultrasound velocity criteria for the stented carotid artery

OBJECTIVES: Ultrasound velocity criteria for the diagnosis of in-stent restenosis in patients undergoing carotid artery stenting (CAS) are not well established. In the present study, we test whether ultrasound velocity measurements correlate with increasing degrees of in-stent restenosis in patients undergoing CAS and develop customized velocity criteria to identify residual stenosis > or =20%, in-stent restenosis > or =50%, and high-grade in-stent restenosis > or =80%. METHODS: Carotid angiograms performed at the completion of CAS were compared with duplex ultrasound (DUS) imaging performed immediately after the procedure. Patients were followed up with annual DUS imaging and underwent both ultrasound scans and computed tomography angiography (CTA) at their most recent follow-up visit. Patients with suspected high-grade in-stent restenosis on DUS imaging underwent diagnostic carotid angiograms. DUS findings were therefore available for comparison with luminal stenosis measured by carotid angiograms or CTA in all these patients. The DUS protocol included peak-systolic (PSV) and end-diastolic velocity (EDV) measurements in the native common carotid artery (CCA), proximal stent, mid stent, distal stent, and distal internal carotid artery (ICA). RESULTS: Of 255 CAS procedures that were reviewed, 39 had contralateral ICA stenosis and were excluded from the study. During a mean follow-up of 4.6 years (range, 1 to 10 years), 23 patients died and 64 were lost. Available for analysis were 189 pairs of ultrasound and procedural carotid angiogram measurements; 99 pairs of ultrasound and CTA measurements during routine follow-up; and 29 pairs of ultrasound and carotid angiograms measurements during follow-up for suspected high-grade in-stent restenosis > or =80% (n = 310 pairs of observations, ultrasound vs carotid angiograms/CTA). The accuracy of CTA vs carotid angiograms was confirmed (r(2) = 0.88) in a subset of 19 patients. Post-CAS PSV (r(2) = .85) and ICA/CCA ratios (r(2) = 0.76) correlated most with the degree of stenosis. Receiver operating characteristic analysis demonstrated the following optimal threshold criteria: residual stenosis > or =20% (PSV >or =150 cm/s and ICA/CCA ratio > or =2.15), in-stent restenosis > or =50% (PSV > or =220 cm/s and ICA/CCA ratio > or =2.7), and in-stent restenosis > or =80% (PSV 340 cm/s and ICA/CCA ratio > or =4.15). CONCLUSIONS: Progressively increasing PSV and ICA/CCA ratios correlate with evolving restenosis within the stented carotid artery. Ultrasound velocity criteria developed for native arteries overestimate the degree of in-stent restenosis encountered. These changes persist during long-term follow-up and across all grades of in-stent restenosis after CAS. The proposed new velocity criteria accurately define residual stenosis >or =20%, in-stent restenosis >or =50%, and high-grade in-stent restenosis > or =80% in the stented carotid artery.     

Surgical management of acute complications and critical restenosis following carotid artery stenting

Carotid artery angioplasty with stenting (CAS) is being increasingly used in the treatment of extracranial carotid artery stenosis. As in other catheter-based approaches to the treatment of arterial disease, surgical intervention may be required because of either acute complications or correct critical restenosis. We have reviewed our experience managing early complications and critical in-stent restenoses after CAS in a tertiary care university hospital and a Veterans Affairs Medical Center. During the last 5 years, 22 carotid arteries (21 patients) underwent CAS. One patient developed thrombosis and rupture of the carotid artery during stenting. Two other patients (3 arteries) developed critical restenosis within 12 months. Subsequent surgical reconstructions included an internal carotid artery (ICA)–to–external carotid artery (ECA) transposition and a common carotid artery (CCA)–to–ICA bypass with reversed saphenous vein (RSV). The patient who underwent CCA–to–ICA bypass later required subclavian–to–ICA bypass because of rapidly progressive intimal hyperplasia and subsequent occlusion of the CCA. The other patient has not had surgical repair because of his deteriorating condition and significant co-morbidities. During the same time period, two additional patients were referred from outside institutions specifically for surgical intervention after carotid stenting. One had delayed rupture of the carotid artery 1 day after stenting and underwent urgent surgical repair. Another patient had early, critical restenosis within the stent and underwent placement of a CCA–to–ICA interposition graft using RSV. Acute treatment failures after CAS can be successfully managed using standard surgical techniques. Patients who develop critical in-stent restenosis requiring surgical repair may need more challenging surgical reconstructions to maintain cerebral perfusion.     

Surgical management of acute carotid thrombosis after carotid stenting: a report of three cases

We report three cases of symptomatic acute carotid thrombosis occurring after carotid artery stenting (CAS). CASE 1: A patient presented with crescendo transient ischemic attacks on the second day after CAS. Ultrasound images demonstrated incomplete in-stent thrombosis due to plaque protrusion. The urgent surgical procedure consisted of stent removal and carotid thromboendarterectomy. CASE 2: A case of complete thrombosis of a carotid stent occurred 4 days after implantation in a patient with essential thrombocythemia diagnosed by chance. The surgical strategy included stent removal and carotid thromboendarterectomy. CASE 3: Cardiac multiple embolisms in a patient with chronic atrial fibrillation caused concomitant leg ischemia and acute carotid stent occlusion 2 hours after CAS. Cerebral reperfusion was established by embolectomy, without removing the stent. At the same time, the right leg ischemia was resolved by a thromboembolectomy with a Fogarty catheter. These three cases demonstrate that acute thrombosis after carotid stenting can be managed successfully with emergent surgical intervention. Thromboendarterectomy with stent removal or in selected cases, simple thromboembolectomy, can minimize neurologic sequelae in patients suffering from acute post-stenting carotid thrombosis.     

In-stent restenosis of innominate artery with critical stenosis of right internal carotid artery

A lady with aortitis syndrome developed in-stent restenosis (ISR) of the innominate artery stent and critical stenosis of right internal carotid artery. The therapeutic challenge was gaining access to the carotid vessel, after treating the innominate artery ISR and all the while using distal protection to circumvent potential cerebral embolism. Percutaneous transluminal angioplasty (PTA) with or without stenting is a safe therapeutic option for re-vascularization of the supra aortic vessels. In the event of re-stenosis, re-treatment with PTA and stenting is safe. Ample evidence-base exists now for carotid artery stenting (CAS) in preference to carotid endarterectomy in patients with stenotic lesions of the carotid vessels.     

Case of symptomatic subacute in-stent thrombosis after carotid angioplasty and stenting for severe carotid stenosis

We report a case of symptomatic subacute in-stent thrombosis after carotid artery angioplasty and stenting (CAS). The patient was a 72-year-old man who had severe asymptomatic right carotid artery stenosis. He received CAS with distal protection, and gained 100% opening of the right carotid artery. The administration of dual antiplatelet therapy (Aspirin 100 mg/day+Cilostazol 100 mg/day), which had been given since two weeks before the procedure, was continued afterwords. On the seventh day after the stent placement, the patient showed sudden onset of left hemiparesis and conjugated deviation of both eyes to the right side and followed by falling into a comatose state. Emergency angiography showed near occlusion of the right carotid artery, suggesting subacute in-stent thrombosis. In conjunction with the intravenous administration of tissue plasminogen activator (1300,000 IU), we performed additional stent placement on the stented portion of the ICA and gained full recanalization of the ICA about three hours after the onset of the symptoms. The patient showed rapid recovery and returned home with slight clumsiness of his right hand. Symptomatic subacute in-stent thrombosis after CAS is a rather rare complication. We discuss on the possible cause of this and stress the necessity of an additional emergency stenting to gain rapid recanalization.     

Complications of carotid artery stenting

AIM: The aim of this study was to deal with complications that can be managed by vascular surgery. METHODS: From March 2000 through May 2004, 171 patients (112 male, 59 female, mean age 66.2 years) underwent carotid artery stenting (CAS). Of these 171 interventions, 154 were CAS with percutaneous trasluminal angioplasty (PTA), 5 CAS without PTA, and 12 patients had only a PTA. RESULTS: In 171 patients who received CAS, 5 suffered a stroke within 7 days and 3 a transient ischemic attack. Twenty-one percent of the patients developed an in-stent restenosis >50% within 6 months following the intervention. Twenty-two patients with a recurrent in-stent restenosis were treated by re-PTA. Eight patients of this group of 22 re-PTAs developed a recurrent in-stent restenosis. They were converted with patch angioplasty or PTFE interposition. These 8 conversions were performed without morbidity or mortality. CONCLUSIONS: The preferable operative technique in patients with recurrent in-stent restenosis is open conventional operation with stent removal and patch angioplasty or graft interposition. The procedure can be performed at a low risk. In our series, we had no morbidity and mortality, and no cranial nerve lesion.     

Successful recanalization by in-stent percutaneous transluminal angioplasty with distal protection for acute carotid stent thrombosis

A 71-year-old male presented with severe left cervical internal carotid artery stenosis manifesting as repeated transient ischemic attacks consisting of right hemiparesis and motor aphasia. Carotid artery stenting (CAS) under distal protection was performed to prevent further ischemic events. This procedure was uneventful. However, the patient exhibited progressive right hemiparesis and motor aphasia 3 days after CAS. Emergent angiography revealed carotid artery occlusion due to in-stent thrombosis. In-stent percutaneous transluminal angioplasty (PTA) was performed under distal protection. The carotid artery was recanalized with small residual thrombus. The neurological deficits almost completely disappeared after PTA. Follow-up angiography 9 months after stenting showed restenosis but no in-stent thrombosis. Carotid thrombosis after CAS can be resolved by in-stent PTA under distal protection and subsequent treatment with antithrombotic agents.     

脑保护装置下支架置入术治疗重度颈动脉狭窄

目的探讨脑保护装置下行颈动脉支架置入术(CAS)治疗重度颈动脉狭窄的近期疗效和安全性。方法回顾性分析2013年10月—2014年12月收治的48例接受CAS治疗的重度颈动脉狭窄患者临床资料,术后随访观察支架内再狭窄、短暂性脑缺血发作(TIA)、脑卒中及死亡事件的发生率。结果48例患者均CAS成功,术前平均狭窄率为(85.27±11.52)%,术后残余狭窄率为(18.12±3.36)%,差异有统计学意义(P0.01)。术后随访无新发TIA、脑梗死及死亡患者,但3例患者出现支架内重度再狭窄。结论支架置入术治疗重度颈动脉狭窄是安全、有效的,但远期疗效有待观察。     

药物洗脱球囊治疗颈动脉支架植入后支架内再狭窄进展

颈动脉狭窄患者接受颈动脉支架（CAS）植入术后可发生支架内再狭窄（ISR）,发生率约5%~20%;药物洗脱球囊（DEB）技术用于治疗CAS植入后再狭窄已取得显著成效。本文对DEB治疗CAS植入术后ISR研究进展进行综述。     

In-stent restenosis after carotid angioplasty-stenting: incidence and management

PURPOSE: Carotid angioplasty-stenting (CAS) has been advocated as an alternative to carotid endarterectomy (CEA) in patients with restenotic lesions after prior CEA, primary stenoses with significant medical comorbidities, and radiation-induced stenoses. The incidence of restenosis after CAS and its management remains ill defined. We evaluated the incidence and management of in-stent restenosis after CAS. METHODS: Patients with asymptomatic (61%) and symptomatic (39%) carotid stenosis of > or = 80% underwent CAS between September 1996 and May 2000; there were 50 procedures and 46 patients (26 men and 20 women). All patients were followed up clinically and underwent duplex ultrasonography (DU) at 3- to 6-month intervals. In-stent restenoses > or = 80% detected with DU were further evaluated by means of angiography for confirmation of the severity of stenosis. RESULTS: No periprocedural or late strokes occurred in the 50 CAS procedures during the 30-day follow-up period. One death (2.2%) that resulted from myocardial infarction was observed 10 days after discharge following CAS. During a mean follow-up period of 18 +/- 10 months (range, 1-44 months), in-stent restenosis was observed after four (8%) of the 50 CAS procedures. Angiography confirmed these high-grade (> or = 80%) in-stent restenoses, which were successfully treated with balloon angioplasty (3) or angioplasty and restenting (1). No periprocedural complications occurred, and these patients remained asymptomatic and without recurrent restenosis over a mean follow-up time of 10 +/- 6 months. CONCLUSIONS: We recommend CAS for post-CEA restenosis, primary stenoses in patients with high-risk medical comorbidities, and radiation-induced stenoses. In-stent restenoses occurred after 8% of CAS procedures and were managed without complications with repeat angioplasty or repeat angioplasty and restenting.     

In-stent Restenosis After Carotid Angioplasty and Stenting: A Challenge for the Vascular Surgeon

PURPOSE: This study aims to review the incidence of in-stent restenosis (ISR), the factors which determine restenosis, and to evaluate the use of various endovascular techniques for the management of ISR following carotid artery stenting (CAS). METHODS: Four hundred and seven patients (334 men, mean age 63 years, range 46-86, median 65 years) were treated with CAS between December 2000 and March 2004. Three hundred and seventy-two (89%) patients had at least one ultrasound evaluation performed 6 months after procedure (range 6-40). Recurrent stenosis >80% detected with duplex ultrasound scans were further evaluated by angiography and treated with repeat endovascular procedure. RESULTS: CAS was performed successfully in all cases with a Carotid WallStent (Boston Scientific) using a cerebral protection device (filter). Perioperative complications included four (0.9%) minor and two (0.4%) major strokes these latter two patients died at 5 and 12 days after the operation. No other deaths occurred. A total of 15 carotid arteries (3.6%) in 14 patients had ISR. All ISR were treated with a repeat endovascular procedure: three balloon angioplasty alone, eight angioplasty and secondary stenting, four angioplasty with cutting balloon. Postsurgical restenosis was confirmed to be the only predictive factor for the development of in-stent restenosis (OR 14.5, 95% CI 2.3-113.4, p=0.005). Endovascular treatment of ISR achieved technical success without periprocedurale complications and the absence of significant restenosis over a median follow up time of 12.4 months (range 3.5-30.7). CONCLUSION: Our experience with a large cohort of CAS showed an encouragingly low incidence of ISR (3.6%) and successful treatment by repeat endovascular intervention. We recommend attempting all endovascular possibilities before performing stent removal.     

Follow-up of stented carotid arteries by Doppler ultrasound

OBJECTIVE: Blood flow velocity (BFV) in the carotid artery is altered by stent placement. The significance of these alterations is unknown. In our experience, both standard BFV criteria for stenosis and customized criteria recommended by other authors have led to high rates of false-positive studies. We reviewed our experience with Doppler ultrasonography immediately after extracranial carotid artery stent placement to define criteria for restenosis by BFV. METHODS: Complete carotid angiograms and BFV results were available for 114 patients treated between January 1998 and December 1999. Angiographic images obtained immediately after stent placement and at follow-up were measured for residual or recurrent stenosis by a blinded reviewer according to the North American Symptomatic Carotid Endarterectomy Trial method. Results of BFV studies obtained within 1 week of stent placement were interpreted by using two standard criteria (A, peak in-stent systolic velocity greater than 125 cm/s; B, internal carotid artery-to-common carotid artery ratio greater than 3.0) and two customized criteria (C, peak in-stent velocity greater than 170 cm/s; D, internal carotid artery-to-common carotid artery ratio greater than 2.0). The results of follow-up angiography and the most recent Doppler study were compared for nine patients. RESULTS: On the basis of an examination of Doppler studies obtained immediately after stent placement, 36 patients met Criterion A for stenosis according to measured BFV (corresponding mean angiographic stenosis, 14.73 +/- 18.45%), 3 patients met Criterion B (mean stenosis, 1.67 +/- 2.89%), 8 patients met Criterion C (mean stenosis, 12.61 +/- 13.18%), and 14 met Criterion D (mean stenosis, 7.98 +/- 21.74%). No patient with Doppler criteria for significant stenosis had more than 50% residual stenosis. Three of nine patients who underwent follow-up angiography had stenosis of 50% or more; of these three patients, two underwent second angioplasty procedures. The peak in-stent systolic velocity or internal carotid artery-to-common carotid artery BFV ratio for each of the three patients with restenosis, but not for the six other patients, had increased by more than 80% since the immediate post-stenting Doppler study. CONCLUSION: Strict BFV criteria for restenosis after carotid artery stenting are less reliable than change in BFV over time. An immediate post-stenting Doppler study must be obtained to serve as a reference value for future follow-up evaluation.     

Sonographische Verlaufskontrolle nach Karotisstentimplantation (CAS): Graduierung von Rezidivstenosen und Stentdislokation

Background

Color-coded duplex sonography (CCDS) is a recognized method in the diagnostics and grading of recurrent stenoses after carotid artery stent (CAS) placement. The peak systolic velocity (PSV) measured by sonography for quantification of stenoses varies in the literature. Stenosis grading according to the European carotid surgery trial (ECST) criteria for the local stenosis grade and the North American symptomatic carotid endarterectomy trial (NASCET) criteria for the distal stenosis grade has resulted in considerable confusion due to the different grading results for the same velocity limits.

Methods

This article presents a critical review of the literature between 2000 and 2012 on sonographic surveillance and stenosis grading of in-stent recurrent stenoses after CAS placement in consideration of hemodynamic laws and presentation of sonographic grading according to the law of continuity.

Results

The high velocity limits of in-stent stenoses according to the NASCET criteria were transferred to the European stenosis criteria according to the ESCT. As a result the velocity limits for in-stent stenoses were applied which were higher than those of de novo carotid stenoses by more than one third (explained by the rigidity of the stent material). Using an adequate conversion results in only slightly higher PSV values for in-stent recurrent stenoses compared to internal carotid artery (ICA) de novo stenoses. The PSV ratio, defined as PSV in-stent intrastenotic/PSV in-stent prestenotic measurements but in contrast to previous values from the literature in the ICA, not in the common carotid artery (CCA), allows a valid stenosis grading according to the law of continuity (most recurrent stenoses lie in the distal and middle third of stents, away from the bifurcation of the external carotid artery). A ratio >?2 indicates a stenosis of >?50?% and a ratio >?4? a ?>?75?% stenosis. Additionally, the plaque configuration determines the hemodynamic effects (40–75 % reduction in cross-sectional surface with a 50 % reduction in diameter) and as a result the intrastenotic PSV. Stent displacement can be validly assessed due to stent movement in grey value sonography in the time motion mode and color-coded duplex sonography by the current flow signals between the vascular wall and the body of the stent.

Discussion and conclusions

With a standardization of stenosis criteria the velocity limits for in-stent recurrent stenoses are only slightly higher than the known values for de novo stenoses. The PSV ratio (PSV in-stent recurrent stenoses/PSV in-stent prestenotic measured in the ICA) allows the most accurate stenosis grading.     

Endovascular intervention for stenosis following carotid stent-supported angioplasty--a case report

This report is on a patient with symptomatic late restenosis after carotid stent-supported angioplasty (CSSA). Initially, the patient underwent carotid endarterectomy (CEA) with primary closure in response to an index transient ischemic attack 13 months before CSSA. He returned with angiographic evidence of recurrent carotid artery stenosis. A balloon-expandable stent was deployed with technical success. Follow-up angiography 1 year later showed an asymptomatic, noncritical in-stent restenosis (50%). Three years after the initial stent placement, the patient presented with ischemic symptoms and a carotid duplex confirming critical restenosis. The patient was successfully treated by deployment of a stent within a stent and showed significant hemodynamic improvement. This is a case report of late progressive restenosis, which raises concerns about long-term patency of CSSA in patients with aggressive postendarterectomy recurrence.     

Risk factors for restenosis after carotid artery angioplasty and stenting

OBJECTIVES: With carotid artery stenting (CAS) becoming an ever-increasing procedure, we sought to determine risk factors for in-stent restenosis after CAS. METHODS: Consecutive patients undergoing CAS between January 2002 and October 2004 at a tertiary care hospital were retrospectively reviewed. Patient, filter, and stent selection were left to the discretion of the attending surgeon. High-risk patients were defined by significant comorbidities or a hostile neck (prior surgery or radiation, or both), and risk factor analysis was performed. In-stent restenosis was defined as >60%, and selective angiography was performed on patients with an in-stent restenosis >80% by duplex ultrasound imaging. RESULTS: Reviewed were 101 patients (55 men, 46 women) who underwent 109 CAS procedures. Comorbidities were typical for patients with atherosclerosis. In addition, 38% (n = 41) of procedures were performed in patients who had prior neck surgery, of which 29% (n = 32) had previous ipsilateral carotid endarterectomy. Seventeen patients (16%) had a history of neck cancer, and all had prior neck radiation. Median follow-up was 5 months (range, 0 to 30 months). Neurologic complications included three transient ischemic attacks (2.8%) and one nondisabling stroke (0.9%). There were two myocardial infarctions (1.9%) and no periprocedural deaths (30 days), for a combined stroke, myocardial infarction, and death rate of 2.9%. Asymptomatic in-stent restenosis developed in 12 carotids (11%), five of which required endovascular intervention, with a mean of 6 months to restenosis. Univariate Cox proportional hazard regression models were used to determine risk factors for the development of restenosis. Prior stroke, transient ischemic attack, amaurosis fugax, and prior neck cancer were all significant risk factors. When these significant risk factors from univariate analysis were put into multivariate analysis, however, the only marginally significant risk factor was prior neck cancer (P = .06). Kaplan-Meier analysis revealed a cumulative freedom from in-stent restenosis at 24 months of 88% +/- 6% in patients without neck cancer compared with 27% +/- 17% (P = .02) in patients with neck cancer. CONCLUSIONS: CAS has been shown to be safe and effective in high-risk patients, with minimal adverse events.     

Fractured internal carotid artery stent

Carotid artery stenting is gaining wider acceptance as an alternative option in the treatment of carotid artery stenosis. Conventional complications such as stroke and recurrent in-stent restenosis are well documented in the literature. However, we believe that carotid stent complications are underreported. The carotid artery segment has features that are relatively smilar to the femoropopliteal segment with respect to forces affecting the stented segment, which can contribute to stent complications such as fracture. In this article, we present a case of internal carotid artery stent fracture and thrombus formation after the patient was exposed to direct trauma to the chest and neck.     

Carotid stent failure: results of surgical rescue.

AIM: Little data is available on surgical "rescue" of failed carotid stents (CAS). We have analyzed a series of CAS failures treated by conventional open surgery. REPORT: Five patients underwent surgery after CAS failure, either electively (4) or as an emergency (1). Elective surgical "rescue" was for stent restenosis (2 cases) or stent misplacement (2 cases). Emergency surgery was performed for entrapment of the protection system in the stent. Surgical rescue was accomplished by perimedial endarterectomy and "en bloc" plaque and stent extraction in 3 cases, and by vein bypass in 2 cases, with no neurological complications. CONCLUSION: Surgical rescue of failed CAS is effective.     

Operative management of carotid artery in-stent restenosis: first experiences and duplex follow-up.

OBJECTIVES: Carotid Artery Stenting (CAS) may be comparable to Carotid Endarterectomy (CEA) as a durable and effective procedure in stroke prevention. Concern remains about the incidence of restenosis after stenting and its management. We evaluated the surgical management of restenosis after CAS. DESIGN: prospective study. METHODS: between December 1997 and April 2001, 217 CAS procedures were performed in 217 patients (155 men and 62 women; age 70 years +/- 8.2). After a mean of 8 months post-stenting four patients (two symptomatic, two asymptomatic with contralateral occlusion) with severe haemodynamic in-stent restenosis (90-99%) had surgical reintervention. RESULTS: standard CEA with removal of the stent was performed in all four patients. No major complications occurred. Intima hyperplasia showed to be the predominant mechanism leading to in-stent restenosis. All four surgically treated patients remained asymptomatic and without recurrent restenosis over a mean follow-up time of 13 months (range 3-20 months). CONCLUSION: the optimal treatment of in-stent restenosis has yet to be defined, but standard CEA with removement of the stent appears to be feasible.     

Carotid artery stenting in a vascular surgery practice

PURPOSE: We tested the clinical applicability, technical results, and morbidity of carotid angioplasty-stenting (CAS) in the treatment of severe stenosis of the internal carotid artery (ICA) in patients deemed to be high-risk candidates for carotid endarterectomy (CEA). METHOD: After an initial series (1994-1997) of 52 interventions, we adopted the use of a transfemoral access technique and self-expanding stents in late 1997. From Dec 1, 1997, to Mar 31, 2001, 135 CAS procedures were performed on 132 patients with more than 70% (symptomatic) or more than 80% (asymptomatic) stenoses of the ICA. Sixty percent of the patients had no symptoms, and 40% of patients had symptoms. The interventional technique was standardized with the use of a 7F long interventional sheath, balloon pre-dilatation of the stenotic lesion, placement of a self-expanding stent (Wallstent in 12 patients and a SMART stent in 120 patients), and post-balloon dilatation when necessary. Brain protection devices were not used. Patients were given clopidogrel and aspirin before and after the procedure and heparin during the intervention. RESULTS: All procedures except two were completed as planned, with access failure in three patients (2.2%). Residual in-stent stenosis of less than 20% was detected in 14 of 132 stented vessels (11%) and accepted as a satisfactory angiographic outcome. Neurologic complications included one patient with a single-episode transient ischemic attack (TIA; motor-sensory deficit of the hand) occurring 2 hours after CAS. One patient sustained a major stroke after thrombosis of the stented ICA, which occurred 3 days after the CAS procedure and 24 hours after open-heart surgery. A third patient sustained a minor stroke that began intraprocedurally after post-balloon dilatation of the stent, and a fourth patient had another minor stroke with transient aphasia (beginning during the procedure and resolving after 4 hours) and monoparesis of the hand, which resolved after 1 week. All stented vessels remained patent during the follow-up period (range, 2-41 months; mean, 16 plus minus 9 months), with four instances of hemodynamically significant in-stent restenosis. Re-intervention with balloon angioplasty was undertaken successfully at 4 months in one patient with restenosis. The periprocedural mortality rate was 0. CONCLUSION: Carotid stenting can be performed with acceptable safety on carefully selected patients by using meticulous, standardized interventional techniques. It may offer a possibly superior therapeutic alternative for non-CEA candidates. Evolving technological improvements and brain protection devices are likely to enhance its role in the treatment of carotid artery disease in the future. Surgical endarterectomy remains the standard of care for most patients at the present time.     

Carotid artery stenting: is there a need to revise ultrasound velocity criteria?

OBJECTIVES: Ultrasound (US) velocity criteria have not been well-established for patients undergoing carotid artery stenting (CAS). A potential source of error in using US after CAS is that reduced compliance in the stented artery may result in elevated velocity relative to the native artery. We measured arterial compliance in the stented artery, and developed customized velocity criteria for use early after CAS. METHODS: US was performed before and within 3 days after CAS, and after 1 month in a subset of 26 patients. Post-procedural peak systolic velocity (PSV) and end-diastolic velocity (EDV) of the internal carotid artery (ICA), PSV/EDV ratio, and internal carotid artery to common carotid artery ratio (ICA/CCA) were recorded. These were compared with degree of in-stent residual stenosis determined at carotid angiography performed at the completion of CAS. Peterson's elastic modulus (Ep) and compliance (Cp) of the ICA were determined in a subgroup of 20 patients at the distal end of the stent and in the same region in the native ICA before stenting. RESULTS: Ninety CAS procedures were analyzed. Mean (+/-SD) angiographic residual stenosis after CAS was 5.4 +/- 9.1%, whereas corresponding PSV by US was 120.4 +/- 32.4 cm/s; EDV, 41.4 +/- 18.6 cm/s; PSV/EDV ratio, 3.3 +/- 1.2; and ICA/CCA ratio, 1.6 +/- 0.5. PSV was unchanged at 1 month. Post-CAS PSV and ICA/CCA ratio correlated most with degree of stenosis (P <.0001 for both). Only six patients demonstrated in-stent residual stenosis 20% or greater, but the standard US threshold of PSV 130 cm/s or greater (validated for >20% ICA stenosis in our laboratory) categorized 38 of 90 patients as having stenosis 20% or greater. Receiver operator curve analysis demonstrated that a combined threshold of PSV 150 cm/s or greater and ICA/CCA ratio 2.16 or greater were optimal for detecting residual stenosis of 20% or greater, with sensitivity 100%, specificity 98%, positive predictive value 75%, and negative predictive value 100%. After placement of a stent, the ICA demonstrated significantly increased Ep (1.2 vs 4.4 x 10(3) mm Hg; P =.004) and decreased Cp (9.8 vs 3.2 %mm Hg x 10(-2); P =.0004). CONCLUSIONS: Currently accepted US velocity criteria validated in our laboratory for nonstented ICAs falsely classified several stented ICAs with normal diameter on carotid angiograms as having residual in-stent stenosis 20% or greater. We propose a new criterion that defines PSV less than 150 cm/s, with ICA/CCA ratio less than 2.16, as the best correlate to a normal lumen (0%-19% stenosis) in the recently stented ICA. This was associated with increased stiffness of the stented ICA (increased Ep, decreased Cp). These preliminary results suggest that placement of a stent in the carotid artery alters its biomechanical properties, which may cause an increase in US velocity measurements in the absence of a technical error or residual stenotic disease.