Wallstent Endoprosthesis Research Articles

Endovascular Treatment for Bilateral Carotid Stenosis: a Case Report

Abstract Carotid artery stenosis is usually a consequence of thromboembolism or atheroembolism, or it can be secondary to a low-velocity status in the carotid circulation. This disease can also represent an important cause of stroke, being responsible for 7% of all stroke cases. Endovascular techniques were recently proposed as alternative interventions for patients with high risk for endarterectomy. We present the case of a 70-year-old patient, accusing headache, vertigo, and fatigue. Angiography indicated bilateral carotid artery stenosis. Interventional surgery and angioplasty were performed, crossing the stenotic lesions of the left internal carotid artery, followed by the implantation of a Carotid WALLSTENT endoprosthesis. Evolution of the patient was favorable after the endovascular intervention, with significant improvement of the symptoms caused by bilateral carotid stenosis. As a conclusion, decision-making must be modulated in each patient, according to the patient’s anatomy and comorbidities, and the experience of the team performing the procedure.

Postinterventional Passive Expansion of Partially Dilated Transjugular Intrahepatic Portosystemic Shunt Stents

PurposeTo investigate passive transjugular intrahepatic portosystemic shunt (TIPS) stent expansion in patients with intentional “underdilation” (eg, 10-mm stent, 8-mm balloon) during TIPS creation. Materials and MethodsCustom in-house software was developed for objective quantification of cross-sectional stent area from computed tomography (CT) data. The technique was validated by in vitro experiments. The study included 39 patients (22 men; mean age, 59.2 y) who underwent TIPS creation (VIATORR stent graft [W. L. Gore & Associates, Flagstaff, Arizona]; n = 29; WALLSTENT endoprosthesis [Boston Scientific, Marlborough, Massachusetts], n = 10) with stent underdilation. Follow-up CT data of the patients were used to quantify in vivo stent area changes. Data were analyzed by variance analysis and entered into a general linear model to test for interrelations between stent area changes and clinical (eg, cirrhosis grade) and procedural parameters. ResultsIn vitro validation of the in-house software showed good agreement and reproducibility without overestimation of stent area. Mean clinical follow-up time in patients was 787 days (range, 7–2,450 d). At the time of intervention, VIATORR stent grafts and WALLSTENT endoprostheses were dilated to an average of 64.4% ± 2.3% and 65.63% ± 8.52% of nominal area, respectively. At the last imaging follow-up evaluation, this value had increased in all stents to a mean of 87.8% ± 7.9% (VIATORR) and 82.34% ± 19.6% (WALLSTENT) in the TIPS tract (P < .05). Multivariate analysis revealed the time after intervention to be the only predictor of stent area in the TIPS tract. There was no significant association between stent expansion and clinical or procedure-related parameters. ConclusionsThe area of self-expanding stents implanted in the liver for TIPS creation with dilation to less than nominal diameter significantly increases over time. This increase has to be considered as an additional factor influencing the long-term portosystemic gradient.

Three new techniques for creation of a steerable sheath, a 4F snare, and bidirectional sheath inversion using existing endovascular materials

We present three novel techniques for creation of (1) a steerable sheath, (2) a 4F snare device, and (3) dual anterograde and retrograde double-wire percutaneous transluminal angioplasty access technique using a single femoral puncture. These techniques were conceived and bench-tested in our institution, allowing the utilization of inexpensive equipment for complicated endovascular procedures. They offer (1) controlled navigation, no-touch vessel cannulation and cannulation of angulated vessels, contralateral limb of stent grafts, fenestrations, and branches; (2) a low-profile (4F external diameter) modifiable snare with the ability to expand to the size of an entire aneurysm and the ability to undo the snare in case of blockage with other endovascular material; and (3) in situ sheath inversion for concomitant anterograde and retrograde percutaneous angioplasty with a single femoral puncture.

Hydronephrosis after Endovascular Stenting in the Common Iliac Artery

An 82-year-old man was referred to the nephrology division due to a sudden increase in creatinine (from 0.7 to 1.6 mg/dL). Two months earlier, the patient had undergone endovascular treatment with stent implantation (WALLSTENT Endoprosthesis, Boston Scientific, Natick, USA) in the left common iliac artery for peripheral artery disease. A CT scan revealed left hydronephrosis (Picture 1). Dilation of the ureteral tract was observed from the renal pelvis to the lower ureter. The ureteral dilatation ended just proximal to the iliac artery crossing where the stent had been placed (Picture 2), thus indicating that compression of the ureter by the arterial stent was the cause of the ureterohydronephrosis. Hydronephrosis occurs as a complication of surgical reconstruction of the iliac artery (1) or ureteral obstruction due to the presence of iliac artery aneurysms (2). Recently, endovascular stent grafting has become widely used. In addition to contrast-induced nephropathy and cholesterol crystal embolization, ureterohydronephrosis should therefore be considered as a renal complication of endovascular treatment of the iliac artery.

Late colonic stent perforation following chemotherapy

A 67-year-old patient was diagnosed as having a tumor at the splenic flexure of the colon with multiple liver metastases. They were treated with four consecutive cycles of FOX chemotherapy (leucovorin, 5-fluorouracil, and oxaliplatin). A computed tomography (CT) scan of the abdomen showed regression of liver metastases; however, the patient had obstipation, and prestenotic dilation of the colon was observed. A Wallstent enteral endoprosthesis (Boston Scientific International, Natick, MA, USA) was placed, with subsequent normal passage of stool ([Fig. 1]). Following the procedure the patient continued with chemotherapy. One month later, the patient was admitted with nausea, vomiting, and diarrhea. Gastroscopy revealed that the proximal end of the Wallstent endoprosthesis had perforated the stomach. The endoscope could pass through the endoprosthesis, and in this way it reached the descending colon ([Fig. 2]).

Stenting for Stenosing Takayasu Aortitis Following Carotid Artery Stenosis in a 32-Year-Old Patient

Takayasu arteritis is a chronic granulomatous vasculitis with multivessel involvement, causing significant mortality and morbidity in affected individuals. A 32-year-old patient with severe right common carotid stenosis underwent expanded polytetrafluoroethylene graft interposition to the carotid artery. A bare Wallstent endoprosthesis (Boston Scientific Medi-Tech, Natick, MA) was implanted for the abdominal aortic stenosis incidentally diagnosed during follow-up 1 year after the carotid operation while the disease was inactive. Close follow-up of the activity of the vasculitic process is warranted owing to the progression of the vascular lesions or formation of de novo lesions in Takayasu disease.

Minimally invasive retrieval of a dislodged Wallstent endoprosthesis after an endovascular abdominal aortic aneurysm repair

Endovascular abdominal aortic aneurysm repair (EVAR) is being performed more frequently in patients with concomitant iliac artery occlusive disease. We report a case of a 70-year-old male status post angioplasty and stenting of bilateral iliac arteries for occlusive disease who subsequently underwent EVAR for a rapidly expanding abdominal aortic aneurysm (AAA). One month after the placement of the endograft, it was discovered that the previously placed Wallstent had been dislodged during the endovascular abdominal aortic aneurysm repair. Minimally invasive retrieval using an Amplatz Goose Neck Snare was successful in recovering the stent. This case underscores the danger of performing EVAR in the setting of prior iliac artery stenting and the potential complications that may ensue.

Percutaneously placed Wallstent endoprosthesis in patients with malignant distal biliary obstruction.

Seventy-five patients with malignant distal biliary obstruction were treated by percutaneously placed self-expandable Wallstent endoprostheses for palliative drainage. The stent diameter was 1 cm and its length 3.5-10.5 cm. Early complications occurred in 16 patients (21 per cent); they were related to the endoprosthesis in five (7 per cent) and serious in six (8 per cent). The 30-day mortality rate was 15 per cent, with a 1 per cent procedure-related mortality rate. Sixty-five patients died 6-365 (median 87) days after stent insertion and four had recurrence of obstruction after 21-341 (median 152) days. Reobstruction was the result of tumour ingrowth in one patient, angling of the stent in one and an unestablished cause in two. Ten patients were alive without obstruction 31-383 (median 65) days after stent insertion. Percutaneous use of the Wallstent endoprosthesis allows easy insertion; reobstruction is rare.

Endovascular repair of an infected carotid artery pseudoaneurysm

Pseudoaneurysm formation after carotid endarterectomy is a rare but potentially lethal complication. The risks for embolization and continued expansion necessitate repair. Traditional surgical repair of carotid pseudoaneurysms is often technically demanding, and is associated with relatively high morbidity and mortality. Endovascular stent grafts have been used to treat both posttraumatic and postoperative carotid pseudoaneurysms. An endovascular approach to these pseudoaneurysms limits the risks for operative damage to surrounding structures and the potential for substantial blood loss. We present the case of an infected carotid pseudoaneurysm that was successfully treated with a covered stent graft.

Extracranial carotid artery stenting in surgically high-risk patients using the Carotid Wallstent endoprosthesis: midterm clinical and ultrasound follow-up results.

The purpose of this study was to evaluate the feasibility, safety and midterm outcome of elective implantation of the Carotid Wallstent in patients considered to be at high surgical risk. In a prospective study, 54 carotid artery stenoses in 51 patients were stented over a 24-month period. Three patients underwent bilateral carotid artery stenting. Institutional inclusion criteria for invasive treatment of carotid occlusive disease (carotid endarterectomy or carotid artery stenting) are patients presenting with a 70% or more symptomatic stenosis and those with an 80% or more asymptomatic stenosis having a life-expectancy of more than 1 year. All patients treated by carotid artery stenting were considered at high risk for carotid endarterectomy because of a hostile neck (17 patients--31.5%) or because of severe comorbidities (37 patients--68.5%). No cerebral protection device was used. Of the 54 lesions, 33 (61.1%) were symptomatic and 21 (38.8%) were asymptomatic. Follow-up was performed by physical examination and by duplex ultrasonography at 1 month, 6 months, 1 year and 2 years after the procedure. All 54 lesions could be stented successfully without periprocedural stroke. Advert events during follow-up (mean 13.9 +/- 5.7 months) were non-stroke-related death in 6 patients (11.1%), minor stroke in 4 stented hemispheres (7.4%), transient ipsilateral facial pain in 1 patient (1.8%), infection of the stented surgical patch in 1 patient (1.8%) and asymptomatic instent restenosis in 4 patients (7.4%). The percutaneous implantation of the Carotid Wallstent, even without cerebral protection device, appears to be a safe procedure with acceptable clinical and ultrasonographic follow-up results in patients at high surgical risk. But some late adverse events such as ipsilateral recurrence of non-disabling (minor) stroke or instent restenosis still remain real challenging problems.

Use of Balloon-expandable Stents in Transjugular Intrahepatic Portosystemic Shunts in Cases of Wallstent Endoprosthesis Technical Failure and Revision of Shunt Stenosis

Thirteen patients underwent placement of a balloon-expandable stent either at initial transjugular intrahepatic portosystemic shunt (TIPS) creation (n = 3) because of immediate technical failure of the Wallstent or at shunt revision because of failure of the Wallstent to reduce the portosystemic gradient <or=12 mm Hg despite overdilation (n = 2), stenosis of the Wallstent (n = 1), or parenchymal tract shunt stenosis (n = 7). The mean duration of primary patency when balloon-expandable stents were used at initial shunt creation was 162.7 days +/- 110.1 (SD). The time from initial TIPS creation or shunt revision with a Wallstent to placement of a balloon-expandable stent was 88.6 days +/- 115.3. The time from balloon-expandable stent placement to shunt revision (n = 6), most recent follow-up (n = 2), death (n = 1), or liver transplantation (n = 1) was 171.9 days +/- 121.6. No significant difference in shunt patency was found between the Wallstent and balloon-expandable stent (P =.31). Because no added benefit in patency was seen between the balloon-expandable stent and Wallstent, it appears that balloon-expandable stent placement is valuable only when placement of a Wallstent technically fails as a result of its limited radial force or when precision in placement is needed to treat a hepatic vein stenosis near the confluence with the inferior vena cava.

Stenting as first option for endovascular treatment of malignant superior vena cava syndrome.

Endoprostheses were inserted in cancer patients with superior vena cava syndrome to assess their effectiveness as first-choice, initial treatment for relief of symptoms. Wallstent prostheses (n = 73) of various lengths (5-14 cm; median, 7 cm) and diameters (10-16 mm; median, 16 mm) were inserted in 52 cancer patients (51 men, 1 woman; age range, 44-78 years; mean, 63 years) who were diagnosed and confirmed by cavography or phlebography as having superior vena cava syndrome. A single stent was sufficient in 37 patients, two stents were required in 11, three stents in two, and four stents in another two patients. Contraindications for the procedure were severe cardiopathy or coagulopathy. Resolution of symptoms was achieved in all patients within 72 hr. At follow-up, six obstructions, one partial migration to the right atrium, two incorrect placements, and four stent "shortenings" were noted. All were successfully resolved by repeated stenting. Symptom-free survival ranged from 2 days to 17 months (mean, 6.4 months). At the time of this writing, eight patients are alive and have patent stents. The rest have died from their cancer. The Wallstent vascular endoprosthesis is an effective initial treatment in superior vena cava syndrome of neoplastic origin. Morbidity and complications are minimal. Clinical relief of symptoms is rapid; therefore, the Wallstent endoprosthesis is highly recommended as the first choice for palliative treatment of superior vena cava syndrome, especially because the clinical decision for subsequent chemotherapy or radiotherapy or surgery is not in any way prejudiced.

Results of a Multicenter Prospective Randomized Trial of Carotid Artery Stenting vs. Carotid Endarterectomy

53 Background: Carotid artery stenosis (CAS) is a common etiology for ischemic stroke. While carotid endarterectomy (CEA) is a safe and effective treatment for CAS, endovascular therapy using carotid stenting may be a reasonable alternative. This multicenter study was designed to determine if carotid stenting was equivalent to CEA in patients with symptomatic CAS. Methods: Patients with symptomatic CAS of 60–99% by cerebral angiogram were prospectively randomized to CEA or carotid stenting. All enrolled patients were reviewed by a multidisciplinary team that included neurologists, surgeons, and interventionalists. Patients in the stent group were treated with the WALLSTENT endoprosthesis and received aspirin 325 mg bid and ticlopidine 250 mg bid for 4 weeks. Neurologic assessments were performed 24 hrs post-procedure, then at 1, 6 and 12 months. The primary end-point was ipsilateral stroke, procedure-related death, or vascular death within 1 year. P-values are from 2-sided Fisher’s Exact Test. Results: A total of 219 patients were enrolled; 107 in the stent group (mean age 66.5, 66% male) and 112 in the CEA group (mean age 70, 62% male). The mean baseline degree of stenosis was 76% in the stent group vs 75% in the CEA group. 65% of stent patients had a TIA vs 68% in the CEA group. Median follow-up days for stent and CEA patients were 354 and 341, respectively. The primary end-point rate at approximately one year was 12.1% in the stent group vs. 3.6% for CEA (p = 0.022). The rate of any major stroke was 3.7% for stent vs. 0.9% for CEA (p = 0.204). A post-stent angiogram showed that 97% of patients had less than 30% stenosis. The 30 day peri-procedure complication rate (any stroke or death) was 12.1% for stents and 4.5% for CEA (p = 0.049). The 2 day peri-procedure complication rate was 7.5% for stents and 1.8% for CEA (p=0.055). Other common peri-procedure complications of stenting were severe bradycardia (7%) and groin hematoma (4%). Conclusions: This study did not find that carotid stenting was equivalent to CEA in patients with symptomatic CAS. Based on these data and a futility analysis, the study was terminated before the planned maximum of 700 patients were enrolled.

Endovascular Management of Acute Extensive Iliofemoral Deep Venous Thrombosis Caused by May-Thurner Syndrome

The authors report their experience on the treatment of acute extensive iliofemoral deep venous thrombosis (DVT) due to May-Thurner syndrome using endovascular techniques. During a 1-year period, 10 symptomatic women (age range, 22-52 years; mean, 35.5 years) were referred for treatment. After ascending venography, an infusion catheter system was placed and urokinase was infused locally into the thrombus burden. After near complete clot dissolution (> or = 95%) or lytic stagnation, the residual left common iliac vein narrowing was treated by means of angioplasty and/or placement of Wallstent endoprosthesis. All patients continued to receive oral warfarin. Patients were followed-up by means of clinic visits, and stent patency was assessed by means of duplex Doppler sonography performed at 1, 3, 6, and 12 months, and then yearly thereafter. The total dose of urokinase used and the duration of infusion were 5.87 +/- 2.57 million units (range, 3.18-10.7) and 51.95 +/- 21.57 hours (range, 26.5-89), respectively. After completion of thrombolytic therapy, the iliac vein narrowing was successfully treated by deployment of a Wallstent endoprosthesis in all 10 patients because of failure of angioplasty. No major bleeding complications occurred. Initial clinical success was 100%, with complete resolution of symptoms in all patients. One patient, who was hypercoagulable and was receiving chemotherapy for metastatic adenocarcinoma, had recurrent symptomatic acute DVT 1 month after therapy. She underwent successful repeated lysis. The remaining nine patients were asymptomatic, with a mean follow-up of 15.2 months (range, 6-36 months). One asymptomatic patient, at 36-month follow-up ultrasound, had iliac vein occlusion and well-developed venous collaterals. Serial ultrasonography in all 10 patients showed no evidence of valvular insufficiency in the femoral and popliteal veins. Catheter-directed thrombolytic therapy for the treatment of acute extensive iliofemoral DVT due to May-Thurner syndrome is an effective method for restoring venous patency and provides relief of the acute symptoms. The underlying left common iliac vein lesion invariably needs to undergo stent placement.

Successful Wallstent Implantation for Extensive Iatrogenic Renal Artery Dissection in a Patient with Fibromuscular Dysplasia

Purpose: To describe a case of renal artery stenosis with fibromuscular dysplasia (FMD) and extensive iatrogenic dissection treated with Wallstent implantation. Methods and Results: An 83-year-old woman with a history of coronary artery disease and hypertension presented at another facility with exertional angina and poorly controlled hypertension. Renal arteriography uncovered a critical right renal artery stenosis with severe FMD. However, angioplasty resulted in extensive dissection of the renal artery, for which the patient was referred to our institution. The renal artery was recanalized via the left brachial approach with restoration of flow using a Wallstent and a Palmaz stent. The patient's blood pressure was controllable after this procedure, and follow-up duplex imaging with flow velocities at 6 months showed patent right renal artery stents. Conclusions: Owing to its length and flexibility, the Wallstent endoprosthesis was a useful treatment modality in this case of extensive renal artery dissection.

The Wallstent Endoprosthesis

The Wallstent endoprosthesis is the most widely used self-expanding metal stent for treating digestive disease worldwide. This article presents detailed metallurgical and physical information on the Wallstent endoprosthesis, and addresses implications for its clinical use. Detailed product information provides technical insight into the implantable stent and associated delivery systems. Current worldwide product indications and configurations are discussed, as well as insight into new products in clinical evaluation.

Treatment of Inferior Vena Cava Anastomotic Stenoses with the Wallstent Endoprosthesis after Orthotopic Liver Transplantation

To evaluate the efficacy of the Wallstent endoprosthesis for treatment of stenotic or occlusive inferior vena cava (IVC) lesions refractory to balloon angioplasty in patients after orthotopic liver transplantation. Wallstent endoprostheses were implanted in six patients with IVC anastomotic stenoses or occlusions that were refractory to balloon angioplasty. Follow-up included both duplex ultrasound (US) and clinical evaluations. Ten stents were successfully implanted in six patients. Five of six patients (83%) demonstrated primary patency on duplex US for a mean period of 11 months (range, 4-17 months). One patient's symptoms recurred within 3 weeks after intervention. This patient underwent repeated stent placement. Follow-up duplex US in this patient demonstrated primary assisted patency at 7 months. Mean clinical follow-up was 12 months (range, 7-18 months). Other than the previously described case, no patient developed recurrent symptoms of IVC stenosis or occlusion. Two patients who experienced hemorrhagic complications secondary to anticoagulation were treated successfully. The Wallstent endoprosthesis is a useful adjunct for treatment of IVC stenosis or occlusions in patients who have undergone orthotopic liver transplantation when these lesions are refractory to simple balloon angioplasty.

Self-Expanding Wallstent Endoprosthesis for Malignant Ureteral Obstruction

We present our experience with the self-expanding Wallstent endoprosthesis for ureteral recanalization in obstructive uropathy secondary to malignant pelvic disease. In total, 19 stents were insert...

A new design of the esophageal Wallstent endoprosthesis resistant to distal migration.

Because plastic-covered metallic stents used in the palliation of patients with unresectable esophageal cancer are associated with significant rates of migration, particularly when the lower end of the stent projects into the gastric fundus, the purpose of this study was to establish whether two new prototype designs of the Wallstent esophageal endoprosthesis are prone to migration. A cylindrical stent and a conical stent were studied. Both designs included plastic covering inside the metallic mesh. In addition, the conical device incorporated a variation in the braiding angle between the upper and lower parts of the endoprosthesis. Ten conical stents and eight cylindrical stents were inserted in 18 patients with tumors involving the gastroesophageal junction who were followed up with esophagography and endoscopy. All insertions of stents were successful. Two cylindrical stents (25%) migrated distally. Two conical stents (20%) migrated proximally. One perforation occurred that was associated with distal migration of a cylindrical stent. The frequency of distal migration of cylindrical stents is unacceptably high. Conical stents are resistant to distal migration, although improvements in design are required to deal with the problem of proximal migration.

Ex vivo human carotid artery bifurcation stenting: Correlation of lesion characteristics with embolic potential

Purpose: To develop an ex vivo human carotid artery stenting model that can be used for the quantitative analysis of risk for embolization associated with balloon angioplasty and stenting and to correlate this risk with lesion characteristics to define lesions suitable for balloon angioplasty and stenting. Methods: Specimens of carotid plaque (n = 24) were obtained circumferentially intact from patients undergoing standard carotid endarterectomy. Carotid lesions were prospectively characterized on the basis of angiographic and duplex findings before endarterectomy and clinical findings. Specimens were encased in a polytetrafluoroethylene wrap and mounted in a flow chamber that allowed access for endovascular procedures and observations. Balloon angioplasty and stenting were performed under fluoroscopic guidance with either a Palmaz stent or a Wallstent endoprosthesis. Ex vivo angiograms were obtained before and after intervention. Effluent from each specimen was filtered for released embolic particles, which were microscopically examined, counted, and correlated with various plaque characteristics by means of multivariate analysis. Results: Balloon angioplasty and stenting produced embolic particles that consisted of atherosclerotic debris, organized thrombus, and calcified material. The number of embolic particles detected after balloon angioplasty and stenting was not related to preoperative symptoms, sex, plaque ulceration or calcification, or artery size. However, echolucent plaques generated a higher number of particles compared with echogenic plaques ( p < 0.01). In addition, increased lesion stenosis also significantly correlated with the total number of particles produced by balloon angioplasty and stenting ( r = 0.55). Multivariate analysis revealed that these two characteristics were independent risk factors. Conclusions: Echolucent plaques and plaques with stenosis ≥90% produced a higher number of embolic particles and therefore may be less suitable for balloon angioplasty and stenting. This ex vivo model can be used to identify high-risk lesions for balloon angioplasty and stenting and can aid in the evaluation of new devices being considered for carotid balloon angioplasty and stenting. (J Vasc Surg 1998; 27:463-71)