Irene Boos

Effect on Intimal Hyperplasia of Dexamethasone Released from Coated Metal Stents Compared with Non-Coated Stents in Canine Femoral Arteries

AbstractPurpose: Polymer-coated, dexamethasone (DXM)-releasing stents were tested in order to assess the efficacy of DXM released locally for the prevention of stent restenosis due to intimal hyperplasia. Methods: Strecker stents coated with a biodegradable membrane containing DXM were implanted percutaneously into the femoral artery in 14 dogs. The contralateral artery received a conventional non-coated stent serving as control. The drugs are eluted by degradation of the carrier membrane. Follow-up intraarterial digital subtraction angiography (DSA) was obtained at 3, 6, 9, 12, and 24 weeks with subsequent autopsy. Specimens for gross and microscopic pathology were obtained and histomorphometry was performed. Results: Four of 14 DXM-coated stents showed thrombotic occlusion within the first 3 weeks; ten DXM-coated stents remained patent. At follow-up DSA, DXM-coated stents showed a significantly wider lumen than the non-coated stents. At morphometry there was less intimal hyperplasia over DXM-coated stents than over non-coated stents (p<0.05). Conclusion: DXM-coated stents reduce neointimal hyperplasia in dogs when compared with non-coated stents.

Popliteal Artery Stenting Using Flexible Tantalum Stents

AbstractPurpose: 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.

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.

Nitinol Esophageal Stents: New Designs and Clinical Indications

AbstractPurpose: To evaluate the clinical use of covered and noncovered, knitted nitinol stents in patients presenting new stent indications. Methods: Self-expandable, knitted nitinol stents were implanted in four patients for treatment of dysphagia. In two patients who had malignant strictures and had esophago-respiratory fistulae and in one patient with an esophagocutaneous fistula, polytetrafluoroethylene (PTFE)-covered stents were implanted. One patient received a noncovered stent, but a retrograde approach through a percutaneous endoscopic gastrostomy (PEG) fistula had to be chosen for recanalization of an esophageal occlusion. Two patients received stents for treatment of benign strictures. Results: Recanalization of the stricture and stent implantation were performed under fluoroscopic control without any procedure-related morbidity or mortality. Dysphagia improved in all patients and the esophageal fistulae could be sealed off by covered stents. During a maximum follow-up of 18 months, there was no stent migration or esophageal perforation. Complications observed were stent stenosis due to food impaction (1/4) and benign stent stenosis (2/2). Most complications could be treated by the interventional radiologist. Conclusion: Self-expandable, covered Nitinol stents provide an option for the treatment of dysphagia combined with esophageal fistulae. In combination with interventional radiology techniques, even complex strictures are accessible. For benign strictures, the value of stent treatment has not yet been proven.

Flexible tantalum stents for the treatment of renovascular hypertension: a 10-year experience

Abstract. The aim of this study was to determine long-term success of flexible tantalum stents for the treatment of ostial and truncal renal artery stenosis. Since 1989, flexible tantalum stents (type Strecker) were implanted in 34 patients (36 arteries, 25 ostial lesions, 11 truncal lesions) with uncontrollable renovascular hypertension, 9 of them in association with renal insufficiency. Stents were placed unilaterally in 32 patients, and bilaterally in 2 patients for the treatment of renal artery stenosis. Thirty-five of 36 lesions were atherosclerotic, including 5 recurrencies after previous percutaneous transluminal renal angioplasty (PTRA). One patient had Takayasu arteritis. Stents were implanted after unsuccessful PTRA of 11 truncal and 23 ostial lesions, and as a primary procedure in 2 ostial lesions. Follow-up examinations included blood pressure measurement, determination of serum creatinine level, color duplex sonography, or angiography. The technical success rate was 92 %. Technical failure included incorrect stent placement (1 of 36 lesions, 2.8 %), and stent dislocation (2 of 36 lesions, 5.6 %), and two stents were retrieved percutaneously. In one case of Takayasu arteritis, residual stenosis of 40 % was observed. After technically successful stent placement, 77 % of patients became normotensive with or without medication. In the remaining patients there was partial improvement with blood pressure between 140 and 180 mmHg. Renal function improved in 76 % of patients (completely in 3 of 8, 38 %; and partially in 3 of 8, 38 %). Primary patency rate including all stented lesions and initial technical failures was 82.4 % ± 6.8 (1 year) and 82.4 % ± 9.2 (3 years). After technically successful stent placement, patency rates were 89.9 ± 5.6 % (1 year), and 89.9 ± 7.6 % (3 years). For ostial lesions, primary patency rate was 87.9 ± 6.7 % (1 year) and 87.9 ± 9.2 % (3 years). Placement of flexible tantalum stents in renal arteries is technically demanding, especially in ostial lesions. Once placed successfully, stent patency rate is excellent.

Intraarterial infusion therapy via a subcutaneous port for limb-threatening ischemia: a pilot study.

AbstractPurpose: To present the initial results of a new percutaneously implantable catheter port system (PIPS) used for long-term intraarterial infusion therapy in patients with severe ischemic limb disease. Methods: Ten patients with deep, extended ischemic ulcerations (all 10) and osteomyelitis (6/10) of the foot received intraarterial infusions of prostaglandine E1 and antibiotics, if indicated, via a new port catheter system with the port placed subcutaneously above the groin after percutaneous introduction and the catheter tip placed into the superficial or deep femoral artery. Results: Port implantation and repeated port access were uncomplicated. During the follow-up period (mean 11 months, range 1 week–50 months), port migration, leakage, or infection was not observed. Three catheters thrombosed and were opened by fibrinolysis with recombinant tissue plasminogen activator instilled via the port. Treatment success was achieved in 8 patients: relief from rest pain (8 patients), reduction of ulcer size (4/8), and complete healing (4/8). Limb savage rate was 80%. In 2 patients amputation could not be avoided. Conclusion: Selective long-term arterial infusion therapy presents a valuable therapeutic regimen for limb salvage. With the new catheter port system, repeated local intraarterial infusion is safe and simple.

Three year results of endovascular therapy with a new generation nitinol stent for femoro-popliteal artery lesions - a single-center outcome analysis of a subcohort of MISAGO 2 study

BACKGROUND Advances in stent technology have widened the field of indications for stent treatment of femoro-popliteal artery lesions, however the use of stents in bending arterial segments is restricted because some first- and second-generation nitinol stent designs did not respond well to the mechanical forces of femoro-popliteal segments in motion which pose a substantial risk of stent fracture inducing in-stent-stenosis. New generation nitinol stents are supposed to overcome these limitations but long-term results are rare. PATIENTS AND METHODS In forty-five patients (mean age 68 y, range 50 - 85) with peripheral arterial disease (TASC II A-C, Rutherford category 2 - 5) forty-six lesions of the superficial femoral artery (37) or popliteal artery (9) were treated [25 high-grade stenoses, mean length 53 mm (range 30 - 145 mm); 21 chronic total occlusions, mean length 74 mm (range 30 - 180 mm)]. 74 % of lesions were located in the mobile bending arterial segments in the distal femoral or the popliteal segment. Clinical reevaluation performed at discharge, at 6, 12, 24, and 36 months included at least the measurement of ankle-brachial index (ABI) and duplex sonography. RESULTS Procedural success rate was 100 %. At 6, 12, 24, and 36 months, cumulative primary patency rate was 93.5 %, 84.8 %, 80.5 %, and 74.3 % (SE<10); freedom from target lesion revascularization rate was 95.7 %, 89.2 %, 84.9 %, and 79.3 % (SE<10); Rutherford category and ABI improved in all patients and clinical success was maintained in more than 85 % of patients. CONCLUSIONS Sustained technical and clinical success and good clinical long-term results were achieved with Misago™ nitinol stent implantation in femoro-popliteal lesions with moderate risk for in-stent-stenosis, and in the distal femoral and popliteal mobile segment.

Preliminary experience with locoregional intraarterial chemotherapy of uterine cervical or endometrial cancer using the peripheral implantable port system (PIPS): a feasibility study.

AbstractThe purpose of this study was to assess the suitability of a percutaneously implantable catheter port system (PIPS) for repeated intraarterial locoregional chemotherapy (ILC) for cervical and endometrial carcinoma. In 30 patients with advanced, recurrent, or high-risk cervical (n = 23) or endometrial (n = 7) carcinoma, PIPS for ILC was implanted via a femoral access, the catheter localized in the infrarenal abdominal aorta. Chemotherapy was performed adjuvantly after surgery (n = 14) or neo-adjuvantly to enable surgery, or for palliation (n = 16). Port implantation, catheter placement, and repeated port puncture was uneventful in all patients. Complications included catheter dislocation (n = 1), catheter thrombosis (n = 2), subcutaneous infection (n = 1), port-bed skin atrophy (n = 1), requiring port explantation in 3 patients. At 2 years follow-up, complete remission was observed in 7/14 patients with adjuvant chemotherapy, partial remission in 3/14. Successful down-staging could be achieved in 4/8 patients with neo-adjuvant chemotherapy. The PIPS is suitable for repeated ILC which may be a valuable method for pre- and post-surgical therapy of advanced or high-risk cervical and endometrial cancer, for adjuvant chemotherapy as well as neo-adjuvantly for down-staging, or for palliation.

Development of a New Intravascular Low-Profile Device for Exclusion of Aortic Aneurysm: An Experimental Pilot Study

AbstractPurpose: To present a new intravascular device for the treatment of aorto-iliac aneurysms. Methods: This new device was tested in five dogs with abdominal aortic aneurysm created experimentally by overdilation of a balloon-expandable stent with a 16 or 18 mm wide PTA balloon catheter. The design of the device is based on a self-expanding aortic stent which consists of two stretchable circular frames filled with a textile Dacron mesh membrane that is suspended horizontally into the infrarenal abdominal aorta proximally to the aneurysm. The frames are part of a preshaped double helical structure that is introduced longitudinally through a catheter in a parallel fashion and forming the desired shape at the vessel site to be occluded. Two iliac stent-grafts are introduced in a low-profile status through the membrane sealing the aneurysm sac and holding the stent-grafts in place. After stent-graft expansion, a new bifurcation located more proximally than the natural one is created. The follow-up of the dogs was performed clinically and angiographically, and specimens were evaluated histomorphologically. Results: The membrane device can be introduced through a 9 Fr vascular sheath. Technical success was achieved in four of five dogs. Nine of ten stent-grafts could be fixed securely within the membrane, thus preventing dislocation. Aneurysms were excluded immediately, and blood flow to the external iliac arteries was restored by the stent-grafts. At 6–9 months follow-up of technically successful implanted devices, there were no endoleaks, no migration, no stenoses at contact sites between the implant material and vascular wall, and no stenosis or occlusion of the stent-grafts. At microscopic evaluation, the interspace between the membranes was filled with thrombotic material, thus ensuring exclusion of the aneurysm. Conclusion: This new device was found to be flexible, low profile and useful in excluding abdominal aortic aneurysm in the experimental setting.

Improvement in claudication after angioplasty of distal ostial collateral stenosis in patients with long-segment occlusion of the femoral artery

AbstractPurpose: To evaluate the angiographic and clinical effects of percutaneous transluminal angioplasty (PTA) of distal ostial collateral stenoses in patients with claudication and long-segment occlusion of the superficial femoral artery (SFA). Methods: In ten patients (9 men, 1 woman) with stable intermittent claudication due to chronic long-segment occlusion of the SFA a high-grade stenosis of the distal collateral ostium of the deep femoral artery to the popliteal artery were dilated. PTA was performed using popliteal artery access. Claudication distances on the treadmill and ankle-brachial pressure indices (ABI) at rest were analyzed before, 1 week, and 14 weeks after PTA. Results: Initial technical success was obtained in all patients. There were no significant periprocedural local complications. The initial mean claudication distance on the treadmill increased significantly from 107 ± 65 m to 306 ± 209 m (p < 0.01), the maximal claudication distance from 203 ± 128 m to 392 ± 167 m (p < 0.01). The mean ABI changed slightly but significantly (0.61 ± 0.08 vs. 0.64 ± 0.07; p < 0.05). Early follow-up after 14 weeks revealed no clinical deterioration. Conclusion: This new technique is considered helpful in patients with well-defined claudication and long-segment occlusion of the SFA.