The erasme study: A multicenter study on the safety and technical results of the palmaz stent used for the treatment of atherosclerotic ostial renal artery stenosis

Purpose: To assess, in a multicenter setting, safety, technical results, and restenosis rate of the Palmaz stent for treatment of atherosclerotic ostial renal artery stenosis. Methods: Ten centers enrolled 106 patients (120 treated renal artery stenoses) in the study. Patient selection was based on unsuccessful percutaneous transluminal renal angioplasty (residual stenosis ≥ 20%) performed for treatment of ostial stenosis ≥ 50%, in patients with hypertension and/or impaired renal function. Safety was assessed by means of the complication rate, and technical results by the number of successful stent placements and occurrence of restenosis (>50%) at intraarterial angiographic follow-up. Results: Stent placement was successful (n = 112) or partially successful (n = 5) in 117 (98%) arteries. Complications occurred in 19 procedures; seven were of serious clinical significance. Angiographic follow-up was performed in 89 of 117 (76%) cases, at a mean of 8 months (range 2.5–18 months). Fifteen stents (16.9%) showed restenosis (at a mean of 8.5 months), of which 10 were successfully redilated. Conclusion: Renal artery stenting has a high technical success rate, a complication rate comparable to percutaneous transluminal renal angioplasty, and a low rate of restenosis at 8 months angiographic follow-up.     

Noncovered stent placement in a blunt traumatic injury of the right subclavian artery

We report a case of scapulothoracic dissociation with right subclavian artery traumatic injury that was managed by endovascular treatment. Particular features are the use of a flexible self-expandable noncovered stent and simultaneous protection of the right common carotid artery from distal embolization by inflating a balloon catheter.     

Placement of a PTFE-Covered Wallstent Through a 12 Fr Sheath for the Exclusion of a Common Iliac Artery Aneurysm

We describe a technique for transfemoral endovascular exclusion of an iliac artery aneurysm with a reconstrained polytetrafluoroethylene (PTFE)-covered Wallstent inserted through a 12 Fr sheath after right femoral artery cutdown. The procedure was successfully performed, with evidence of complete aneurysm exclusion at 4-month follow-up. This technique reduces the caliber of the introducer needed to deploy the covered Wallstent. It should be noted that because of a leak, an additional covered Palmaz stent was also deployed.     

An Experimental Study of Endovascular Stenting with Special Reference to the Effects on the Aortic Vasa Vasorum

Purpose: To evaluate the effects of bare stents and covered stents on the aortic wall, especially the vasa vasorum. Methods: Eight bare stents and nine covered stents were placed in the infrarenal aorta of nine dogs. The dogs were euthanized at 4–45 weeks after stent placement. The vasa vasorum was evaluated by microstereoscopy with vascular casting, and the histopathology of the aortic wall was examined by light microscopy. Results: In the unstented normal aorta, vasa vasorum nourished the adventitia and the outer media, and the intima and inner media were avascular. In the stented segment, vascular dilatation and proliferation of vasa vasorum, medial atrophy, and intimal hyperplasia were observed, more prominent for covered stents than for bare stents. Conclusion: Intravascular stent placement caused not only medial atrophy and intimal hyperplasia but also proliferation of the vasa vasorum, probably due to hypoxia in the aortic wall. Received: 0/00/00/Accepted: 0/00/00     

Primary stent placement for recanalization of iliac artery occlusions: Using a self-expanding spiral stent

Purpose: To report the clinical results for recanalizations of an occluded iliac artery by a self-expanding spiral stent. Methods: We attempted to recanalize 36 iliac artery occlusions in 34 patients [33 men, 1 woman, aged 51–75 years (average 61.6 years)]. The average lesion length was 6.92 cm (range 1–14 cm). The patients' chief complaints were intermittent claudication and resting pain. Fontaine classification was assigned before and after the procedure. Technical and clinical success were also analyzed. Results: Forty-five stents were successfully deployed in 34 patients. All 36 lesions (13 in the external iliac artery, 12 in the common iliac artery, and 11 in both) were patently recanalized on angiography. The follow-up period ranged from 6 months to 36 months (mean 11.9 months). Fourteen stents (39%) with incomplete expansion were dilated with a balloon catheter. Good technical (100%) and clinical (94%) results were obtained. The only complication was one hematoma at the puncture site. Reocclusions were noted in two lesions (5%) at 1 week and 15 months, respectively. Conclusion: A self-expanding spiral stent is a safe and effective device for recanalization of an iliac artery occlusion as the primary stent without any previous intervention.     

Transluminal Treatment of a Celiac Artery Pseudoaneurysm with a Stent Graft Occlusion Device

This report describes the transluminal placement of a stent graft occlusion device to treat a celiac bypass graft pseudoaneurysm which was causing biliary and duodenal obstruction. Received: 0/00/00/Accepted: 0/00/00     

Palliative Treatment of Malignant Colorectal Strictures with Metallic Stents

Purpose: To assess the effectiveness and safety of self-expanding metallic stents as a primary palliative treatment for inoperable malignant colorectal strictures. Methods: Under radiological guidance 20 self-expanding metallic Wallstents were implanted in 16 consecutive patients with colorectal stenoses caused by malignant neoplasms, when surgical treatment of the condition had been ruled out. The patients were followed up clinically for 1–44 months, until death or termination of this study. Results: The stents were successfully implanted in all cases and resolved the clinical obstruction in all the patients except one, who underwent subsequent colostomy. During follow-up of the remaining 15 patients, clinical complications arising from the procedure were pain (two patients), minor rectal bleeding (one patient), and severe rectal bleeding (one patient) (26%). There were three cases of stent migration and three cases of stent occlusion, and reintervention by us was necessary in 20% of cases (3/15). The mean life span following the procedure was 130 days, and none of the patients exhibited clinical symptoms of obstruction at the time of death (12 patients) or termination of the study (3 patients). Conclusion: Deployment of metallic stents under radiologic guidance is an effective alternative as a primary palliative measure in malignant colorectal obstruction, though the possible clinical complications and need for repeat intervention during follow-up should be taken into account.     

Duplex ultrasonography in assessing restenosis of renal artery stents

Purpose: To determine the accuracy and optimal threshold values of duplex ultrasonography (US) in assessing restenosis of renal artery stents. Methods: Twenty-four consecutive patients with 33 renal arteries that had previously been treated with placement of a Palmaz stent underwent duplex US prior to intraarterial digital subtraction angiography (DSA), which was the reference standard. Diagnostic accuracy of in-stent peak systolic velocity (PSV) and reno-aortic ratio (RAR = PSV renal stent/PSV aorta) in detecting > 50% in-stent restenosis were evaluated by the receiver operating characteristic curve. Sensitivity and specificity were determined using the optimal threshold values, and using published threshold values: RAR > 3.5 and in-stent PSV > 180 cm/sec. Results: Six examinations were technically inadequate. Nine stents had residual or restenosis > 50% at DSA. The two duplex parameters were equally accurate since areas under the curves were similar (0.943). With optimal threshold values of 226 cm/sec for PSV and 2.7 for RAR, sensitivities and specificities were 100% and 90%, and 100% and 84%, respectively. Using the published duplex criteria resulted in sensitivities and specificities of 100% and 74% for PSV, and 50% and 89% for RAR. Conclusion: Duplex US is a sensitive modality for detecting in-stent restenosis if laboratory-specific threshold values are used.     

Low-molecular-weight heparin (reviparin) reduces the incidence of femoropopliteal in-stent stenosis: Preliminary results of an ongoing study

Purpose: To examine the efficacy of the low-molecular-weight heparin, reviparin, for prevention of femoropopliteal stent restenosis. Methods: Forty-two patients who had implantation of flexible tantalum stents for the treatment of stenosis (n= 24) or occlusion (n= 18) of the femoral (n= 27) or popliteal (n= 15) arteries were included in this study protocol. An intraarterial bolus of 5000 IU heparin was given before percutaneous transluminal angioplasty (PTA), and in the case of stent implantation due to unsuccessful PTA, an additional dose of reviparin (3500 anti-factor Xa IU) was given. Postprocedurally, 10,500 anti-factor Xa IU of reviparin were administered intravenously over 24 hr, followed by 3500 anti-factor Xa IU subcutaneously twice a day for 23 days. Oral aspirin (100 mg/day) was prescribed for the long term. Follow-up criteria (maximum follow-up 37 months) were clinical symptoms, Doppler ankle arm indices, color and duplex sonography, and angiography for suspicion of restenosis. Results: Early stent thromboses were not observed. Overall primary patency rate (PPR) was 88% ± 6.0% (1 year) and 74% ± 10.1% (2 years). Major hemorrhagic complications have not occurred. Conclusion: Reviparin administered in a high dose over a period of 24 days is a safe medication regimen and provides excellent patency rates after stent implantation.     

Are Covered Stents Really Effective at Closing Esophagotracheal Fistulas? Results of an Animal Study

Purpose: To determine whether covered self-expanding metal stents successfully exclude experimentally created esophagotracheal fistulas. Methods: Esophagotracheal fistulas were surgically created in the upper third of the esophagus in 12 minipigs and immediately sealed by implantation of a covered self-expanding metal stent (20 mm expanded diameter) in the esophagus. Before the animals were killed, after 3, 7, 14, 28, 30, and 36 days, the position of the stent and the sealing of the fistula were monitored fluoroscopically. The esophagus, trachea, and both lungs were examined histologically. Results: Creation of an esophagotracheal fistula was successful in all cases. All fistulas were widely patent at autopsy. The technical success rate for stent deployment and initial sealing of the fistula was 100%. During follow-up, five stents migrated distally, but none into the stomach. Therefore, the fistula was no longer excluded in five animals. In seven animals the stent sealed the fistula until the death of the animal. Tracheal narrowing necessitated additional tracheal stenting in three animals. Two minipigs died due to aspiration of food. Histologic examination showed signs of aspiration in all animals with stents in place for longer than 2 weeks. Conclusion: This experimental animal study revealed worse results for sealing of esophagotracheal fistulas with covered self-expanding metal stents than have been reported for the clinical use of these devices.     

Percutaneous Endovascular Stent-Graft for Iliac Pseudoaneurysm Following Lumbar Discectomy

In a 24-year-old woman, an iliac pseudoaneurysm following lumbar discectomy was successfully treated by percutaneous placement of a self-expanding stent-graft. A postprocedural angiogram demonstrated complete exclusion of the pseudoaneurysm without leakage of contrast agent.     

Transluminal angioplasty of failing infrainguinal arterial by-pass grafts: Initial and long-term results in 13 patients

Thirteen stenotic infrainguinal arterial bypasses (12 venous, 1 Gore-tex graft) were treated by transluminal angioplasty, either percutaneously (10 patients) or surgically (3 patients). Eleven procedures were immediately successful (two at the proximal portions of femoropopliteal grafts, six near the distal anastomoses, and three at the distal parts of femoroinfrapopliteal grafts) and dilated stenoses are still patent with a mean duration of 24 months in all patients except 2 who died during the follow-up period. The calculated cumulative patency rate is 85% at 36 months. Two procedures were followed by immediate disruption near the distal end of anin situ saphenous bypass graft where balloon inflation was performed. These required immediate surgical repair. Dilatation of the distal ends ofin situ saphenous femoropopliteal bypasses may not be as safe as in other locations.     

Popliteal Artery Stenting Using Flexible Tantalum Stents

Purpose: To evaluate the safety and efficacy of stent therapy for the treatment of residual stenoses after percutaneous transluminal angioplasty (PTA) of popliteal stenoses and occlusions. Methods: In a prospective single-center study, flexible tantalum stents were implanted in 32 popliteal arteries for the treatment of residual stenosis greater than 50% after PTA of stenoses (n = 17) or occlusions (n = 15) in the P1 (n = 16), the P2 (n = 13), or both P1 and P2 segment (n = 3). Follow-up patency was assessed by clinical examination, ankle-brachial index, and color Doppler sonography or angiography. Results: Early stent thrombosis (10 days): 1 of 32 arteries (3%). 1-year and 2-year primary patency rate (PPR): 81% ± 7.1% and 74% ± 9.1%, respectively. 1-year PPRs for subgroups: stented stenoses versus stented occlusions: 88% ± 7.8% vs 73% ± 12.0%, p = 0.12; good lower limb runoff versus poor: 84.0% ± 8.7% vs 76.0% ± 12.4; p = 0.09; P1 versus P2: 77.3% ± 9.8% vs 85.7% ± 9.4%, p = 0.38. Recurrent PTA lesions treated with stents showed higher restenosis rate than de novo lesions. Conclusion: The results of stent therapy of residual popliteal stenosis after PTA are encouraging and warrant further investigation.     

Recurrent TIPS failure associated with biliary fistulae: Treatment with PTFE-covered stents

Purpose: To evaluate the efficacy of covered stents for the treatment of transjugular intrahepatic portosystemic shunt (TIPS) obstruction in human subjects with identified or suspected biliary fistulae. Methods: Five patients were treated for early failure of TIPS revisions. All had mid-shunt thrombus, and four of these had demonstrable biliary fistulae. Three patients also propagated thrombus into the native portal venous system and required thrombolysis. TIPS were revised in four patients using a custom-made polytetrafluoroethylene (PTFE)-covered Wallstent, and in one patient using a custom-made PTFE-covered Gianturco Z-stent. Results: All identified biliary fistulae were successfully sealed. All five patients maintained patency and function of the TIPS during follow-up ranging from 2 days to 21 months (mean 8.4 months). No patient has required additional revision. Thrombosis of the native portal venous system was treated with partial success by mechanical thrombolysis. Conclusion: Early and recurrent failure of TIPS with mid-shunt thrombosis, which may be associated with biliary fistulae, can be successfully treated using covered stents. Stent-graft revision appears to be safe, effective, and potentially durable.     

Determination of stent stenosis: An in vivo experimental comparison of intravascular ultrasound and angiography with histology

Purpose: To compare intravascular ultrasound (IVUS) and angiography with histology in determining the degree of stent stenosis in an in vivo experiment. Methods: In 16 sheep, a total of 64 stents were implanted into the external iliac arteries. Two stents were inserted on either side. Patency was followed by angiography and IVUS. Four types of stent were used: two Dacron-covered (Cragg Endopro and heparinized Cragg Endopro) and two non-covered (Cragg and Memotherm stents). Eight animals were killed after 1 month, eight others after 6 months. Histological sections were prepared from the stented vessels. Measurements of the patent and total stent diameters determined by IVUS, angiography, and histology were compared. Results: Correlation between IVUS and angiography was 0.75, between IVUS and histology 0.77, and between angiography and histology 0.85. A mean stent stenosis of 17 ± 11% (range 0–51%) was found on angiography, of 10 ± 11% (0–46%) on IVUS, and of 20 ± 11% (4%–49%) on histology. In comparison with histology, IVUS underestimated the degree of stenosis by 10 ± 8%, and angiography underestimated it by 3 ± 6%. Resolution of IVUS was calculated to be about 0.35 mm and that of angiography to be about 0.15 mm. Conclusion: Under experimental conditions, IVUS was not superior to angiography in determining the degree of stent stenosis in long-segment stenoses of iliac artery stents, when measurements were correlated with histology. Angiography is sufficient for following the patency of iliac artery stents.     

Primary implantation of polyester-covered stent-grafts for transjugular intrahepatic portosystemic stent shunts (TIPSS): A pilot study

Purpose: To investigate whether placement of a polyester-covered stent-graft increases the primary patency of transjugular intrahepatic portosystemic stent shunts (TIPSS). Methods: Between 1995 and 1997 Cragg Endopro or Passager MIBS stent-grafts were used for the creation of TIPSS in eight male patients, 35–59 years of age (mean 48 years). All patients suffered from recurrent variceal bleeding and/or refractory ascites due to liver cirrhosis. Seven stent-grafts were dilated to a diameter of 10 mm, one to 12 mm. Follow-up was performed with duplex ultrasound, clinical assessment, and angiography. Results: The technical success rate for creation of a TIPSS was 100%. The mean portosystemic pressure gradient decreased from 25 mmHg to 12 mmHg. In seven of eight patients TIPSS dysfunction occurred between 2 days and 3 years after stent-graft placement. In one patient the TIPSS is still primarily patent (224 days after creation). The secondary patency rates are 31 days to 3 years. Conclusion: The primary use of polyester-covered stent-grafts for TIPSS did not increase primary patency rates in our small series.     

Primary stenting for complex atherosclerotic plaques in aortic and iliac stenoses

Purpose: To evaluate the efficacy of primary stenting for complex atherosclerotic plaques in aortic and iliac stenoses that are not amenable to balloon angioplasty alone. Methods: Nineteen patients with complex atherosclerotic plaques were treated with a Palmaz stent (n= 19), Wallstent (n= 1), Strecker stent (n= 1), or Memotherm stent (n= 1). A total of 22 stenoses presenting with complex plaque morphology including ulcerated plaques, ulcerated plaques with focal aneurysms, plaques with heavy calcification, severely eccentric plaques, plaques with overhanging edge, and plaques with spontaneous dissection were stented. The lesions were in the aorta (n= 1), common iliac artery (n= 19), or external iliac artery (n= 2). Results: Immediate angiography after stent placement revealed restoration of patency of the stented segment. Focal aneurysms and ulcerated areas were occluded in the follow-up angiographies obtained 4–12 weeks after the procedure. In one case with poor distal runoff and multiple complex lesions of the iliac artery, subacute occlusion occurred. Clinical and angiographic follow-up (3–46 months) revealed patency of all other stented segments. Conclusion: Primary stenting is an effective and reliable approach for complex plaques in stenoses. Patency of the arterial segment with a smooth lumen can be created without the risk of acute complications such as distal embolization, dissection, or occlusion.     

Magnetic resonance angiography of nonferromagnetic lliac artery stents and stent-grafts: A comparative study in sheep

Purpose: To compare nonferromagnetic iliac artery prostheses in their suitability for patency monitoring with magnetic resonance angiography (MRA) using conventional angiography as a reference. Methods: In experiment 1, three Memotherm stents were inserted into the iliac arteries of each of six sheep: two “tandem” stents on one side and a single stent on the other side. In experiment 2, four prostheses (normal and low-porosity Corvita stent-grafts, Memotherm, ZA-stent) were inserted in each of 11 sheep. Patency was monitored before and 1, 3, and 6 months after insertion with 3D phase-contrast and two 2D time-of-flight sequences (TOF-1: TR/TE = 18/6.9, TOF-2: 13/2.5) with and without contrast at 1.5 T. On 206 coronal MIP images (72 pre-, 134 post-stenting), three readers analyzed 824 iliac segments (206 × 4) for patency and artifacts. Results: There was no difference in the number of artifacts between tandem and single iliac Memotherm stents. The ZA-stent induced significantly fewer artifacts than the other prostheses (p < 0.00001). With MRA, patency of the ZA-stent was correctly diagnosed in 88% of cases, which was almost comparable to nonstented iliac segments (95%), patency of the Memotherm stent in 59%, and of the Corvita stent-grafts in 57% and 55%. The TOF-2 sequence with contrast yielded the best images. Conclusion: MRA compatibility of nonferromagnetic prostheses depends strongly on the design of the device. MRA may be used to monitor the patency of iliac ZA-stents, whereas iliac Memotherm stents and Corvita stent-grafts appear to be less suited for follow-up with MRA.     

Treatment of Complete and Partial Obstruction of the Nasolacrimal System with Polyurethane Stents: Initial Experience

Purpose: To present our experience in the treatment of nasolacrimal occlusion by means of polyurethane stents. Methods: Forty polyurethane stents were placed under fluoroscopic guidance in 35 consecutive patients with epiphora due to total or partial obstruction of the nasolacrimal system. The set designed by Song was used in all patients. The procedure was performed by introducing a guidewire through the superior punctum into the canaliculus and advancing it across the obstruction into the inferior meatus of the nasal cavity. After pulling out the guidewire, the stent was advanced in retrograde fashion and released into the sac and the nasolacrimal duct. Results: The technical success rate was 100%. The average time for the procedure was 25 min (range 10–60 min). Immediate complications were: mild pain (n= 5), severe pain (n= 1), minimal epistaxis (n= 7), and moderate epistaxis (n= 1). No major complications occurred. The last clinical control revealed complete resolution of epiphora in 35 eyes and partial resolution in four; one patient did not improve. Conclusion: This technique for treatment of obstruction of the nasolacrimal system is simple and safe, and may obviate the use of more invasive procedures. Received: 0/00/00/Accepted: 0/00/00     

Percutaneous Endoluminal Bypass of Iliac Aneurysms with a Covered Stent

To evaluate the feasibility of percutaneous treatment of iliac aneurysms, a covered stent was inserted in nine men suffering from common iliac artery aneurysms (six cases), external iliac aneurysms (one case), or pseudoaneurysms (two cases). Placement of the stent was successful in all patients. In one patient, an endoprosthesis thrombosed after 15 days, but was successfully treated by thrombolysis and additional stent placement. At the follow-up examinations (mean period 22 months) all stent-grafts had remained patent. No late leakage or stenosis was observed.