Endovascular stroke treatment does not preclude high thrombolysis rates.

BACKGROUND AND PURPOSE: In 1995 intravenous recombinant tissue plasminogen activator (IVRTPA) was the first reperfusion therapy to be approved in patients with acute ischaemic stroke (AIS). The significance and impact of IVRTPA in times of modern endovascular stroke treatment (EST) were analysed in a German academic stroke centre. METHODS: A retrospective observational cohort analysis of 1034 patients with suspected AIS presenting at the emergency department in 2014 was performed. Patients were evaluated for baseline characteristics, reperfusion procedures, IVRTPA eligibility, clinical outcome, symptomatic intracranial haemorrhage (sICH) and mortality. Data acquisition was part of an investigator-initiated, prospective and blinded end-point registry. RESULTS: In 718 (69%) patients the diagnosis of symptomatic AIS was confirmed. 419 (58%) patients presented within 4.5 h of symptom onset and of those 260 (62%) received reperfusion therapy (IVRTPA alone, n = 183; combination or bridging therapy, n = 60; EST alone, n = 17). Subtracting cases with absolute contraindications for IVRTPA resulted in an effective thrombolysis rate of 82%. sICH occurred in two patients treated with IVRTPA alone (1.1%). The median door-to-needle interval was 30 min. Fifty (17%) non-EST eligible AIS patients presenting within 4.5 h without absolute contraindications did not receive IVRTPA mainly due to mild or regressive symptoms. Most of these untreated IVRTPA eligible patients (82%) were discharged with a good clinical outcome (modified Rankin Scale ≤ 2). CONCLUSIONS: Intravenous recombinant tissue plasminogen activator remains the most frequently applied reperfusion therapy in AIS patients presenting within 4.5 h of onset in a tertiary stroke centre. An effective thrombolysis rate of over 80% can be achieved without increased rates of sICH.

[Aortic bifurcation reconstruction : Endovascular repair and alternatives]. / Rekonstruktion der Aortenbifurkation : Endovaskuläre Versorgung und Alternativen.

CLINICAL ISSUE: Aortic bifurcation disease is a manifestation of arteriosclerosis in about 95% of cases. Stenotic disease of the aortic bifurcation is a special form of peripheral arterial occlusive disease (PAOD). Men older than 60 years are particularly affected. STANDARD TREATMENT: The potential of endovascular therapy has continued to increase. Hereby, the increased availability of hybrid operating suites which allow for a combined use of endovascular techniques and open surgery plays an important role. DIAGNOSTIC WORK-UP: For the decision on the type of therapy and the sizing of the prosthesis, thin-slice CT angiography (CTA) of the abdominal aorta and the iliac arteries including multiplanar reconstructions in the sagittal and coronal planes is sufficient. The inguinal arteries have to be included in the CTA volume. PERFORMANCE: Compared to open surgery, endovascular therapy of aortic bifurcation disease has the advantage of reduced invasiveness. ACHIEVEMENTS: Treatment of aortic bifurcation disease continues to change. In daily practice, the standard treatment of complex aortic bifurcation disease is still open surgery. However, an increasing number of studies indicate that endovascular therapy and open surgery should be considered equivalent, complementary methods. PRACTICAL RECOMMENDATIONS: Good quality preinterventional CTA is important for intervention planning. If you want to offer endovascular therapy as a radiologist, knowledge of interventional skills and close cooperation with clinical colleagues, particularly the vascular surgeon, is mandatory.

Neurothrombectomy in acute ischaemic stroke: a prospective single-centre study and comparison with randomized controlled trials.

BACKGROUND AND PURPOSE: In the last few months five multicentre, randomized controlled trials (RCTs) unequivocally showed the superiority of mechanical thrombectomy in large vessel occlusion acute ischaemic stroke compared to systemic thrombolysis. Despite varying inclusion criteria and time intervals from onset to revascularization overall increases of good functional outcome between 55% and 81% were reported. However, only a minority of screened patients (approximately 1%) were eligible for intra-arterial (IA) therapy. METHODS: An investigator-initiated, single-centre, prospective and blinded end-point analysis was performed of 3123 consecutive patients with acute ischaemic stroke presenting between February 2010 and December 2014. RESULTS: One hundred and fifty-four patients [4.9%, age (years) mean (SD), median (interquartile range) 71.2 (±14), 74.7 (65.9-81.4)] met the inclusion criteria of sparse early ischaemic signs on initial standard cranial computed tomography (CT) (ASPECT score ≥7), large vessel occlusion in the anterior circulation on CT angiography and start of treatment within 6 h of onset of symptoms. After consensual interdisciplinary treatment decisions 130 patients (4.2%) received IA treatment - in the majority stent-assisted thrombectomy in combination with intravenous (IV) recombinant tissue plasminogen activator - and 24 patients (0.7%) standard IV thrombolysis. On 3 months' follow-up an overall significant improvement of disability (P = 0.05) as measured by the modified Rankin Scale was shown in favour of the IA treatment group. Good functional outcome was achieved in about twice as many patients (IA vs. IV, 41.2% vs. 21.2%; P = 0.078). CONCLUSION: By choosing pragmatic inclusion criteria state-of-the-art IA therapy of a specialized tertiary stroke centre can be safely applied under real-world conditions to a higher percentage of patients with similar success to the recently published RCTs.

Clinical Impact of Ventilation Duration in Patients with Stroke Undergoing Interventional Treatment under General Anesthesia: The Shorter the Better?

BACKGROUND AND PURPOSE: Whether general anesthesia for neurothrombectomy in patients with ischemic stroke has a negative impact on clinical outcome is currently under discussion. We investigated the impact of early extubation and ventilation duration in a cohort that underwent thrombectomy under general anesthesia. MATERIALS AND METHODS: We analyzed 103 consecutive patients from a prospective stroke registry. They met the following criteria: CTA-proved large-vessel occlusion in the anterior circulation, ASPECTS above 6 on presenting cranial CT, revascularization by thrombectomy with the patient under general anesthesia within 6 hours after onset of symptoms, and available functional outcome (mRS) 90 days after onset. RESULTS: The mean ventilation time was 128.07 ± 265.51 hours (median, 18.5 hours; range, 1-1244.7 hours). Prolonged ventilation was associated with pneumonia during hospitalization and unfavorable functional outcome (mRS ≥3) and death at follow-up (Mann-Whitney U test; P ≤ .001). According to receiver operating characteristic analysis, a cutoff after 24 hours predicted unfavorable functional outcome with a sensitivity and specificity of 60% and 78%, respectively. Our results imply that delayed extubation was not associated with a less favorable clinical outcome compared with immediate extubation after the procedure. CONCLUSIONS: Short ventilation times are associated with a lower pneumonia rate and more favorable clinical outcome. Cautious interpretation of our data implies that whether patients are extubated immediately after the procedure is irrelevant for clinical outcome as long as ventilation does not exceed 24 hours.

[Reconstruction of the aortic bifurcation: endovascular aortic repair (EVAR) and alternatives]. / Rekonstruktion der Aortenbifurkation: "Endovascular aortic repair" (EVAR) und Alternativen.

CLINICAL ISSUE: Diseases of the aortic bifurcation, whether stenotic or dilating, are mostly a manifestation of arteriosclerosis. If only stenosis is present aortic bifurcation disease is equivalent to a certain form of peripheral arterial occlusive disease (PAOD) characterized by the specific anatomical location. Aneurysmal disease and PAOD of the aortic bifurcation may occur together and men older than 60 years are particularly affected. The main symptom of aortic bifurcation PAOD is bilateral claudication whereas aneurysmal disease of the aortic bifurcation is frequently asymptomatic. STANDARD TREATMENT: Therapy of stenotic and aneurysmal disease of the aortic bifurcation depends on the degree of the disease. Simple lesions, such as isolated stenoses of the aortic bifurcation or unilateral occlusions of the common iliac artery extending to the aortic bifurcation have been treated endoluminally for many years. Current standard treatment of complex aortic bifurcation disease is open surgery with implantation of an aortobifemoral bypass graft. However, recent developments in less invasive endoluminal methods have shifted the indications more towards endoluminal therapy. This development is mirrored by the international TransAtlantic Inter-Society Consensus (TASC) II recommendations from 2007 and even more clearly by the current national S3 guidelines on PAOD (http://www.degir.de/site/leitlinien). It is stated that in complex aortic bifurcation disease, such as bilateral occlusions of the common iliac arteries (TASC C lesions) or diffuse aortobiiliac stenoses and occlusions (TASC D lesions), endoluminal therapy may be considered as an alternative to open surgery. Therapy of aneurysmal disease of the aortic bifurcation depends on the pathoanatomical conditions. Prerequisite for endoluminal therapy is a sufficient landing zone for the prostheses. If this prerequisite is fulfilled endoluminal therapy is very likely comparable to open surgery with regard to technical and clinical success. Long-term results are still lacking. DIAGNOSTIC WORK-UP: For the decision on the type of therapy and the sizing of the prostheses, thin-slice (≤ 3 mm slice thickness) computed tomography angiography (CTA) of the abdominal aorta and the iliac arteries including multiplanar reconstruction in the sagittal and coronal plane are sufficient. The inguinal arteries have to be included in the CTA volume. PERFORMANCE: Compared to open surgery, endoluminal therapy of stenotic and aneurysmal disease of the aortic bifurcation has the advantage of reduced invasiveness. Hence patient recovery and hospital stay may be shorter. ACHIEVEMENTS: Therapy of stenotic and aneurysmal disease of the aortic bifurcation is changing. Standard treatment of complex aortic bifurcation disease, which is open surgery is extended by the possibilities of endoluminal methods. Due to improvements in current endoluminal systems and development of new techniques, the importance of endoluminal therapy will further increase. PRACTICAL RECOMMENDATIONS: Good quality of the preinterventional CTA is important for planning the intervention. In order for a radiologist to offer endoluminal therapy, besides knowledge of interventional skills a close cooperation with clinical colleagues, in particular vascular surgeons is mandatory.

[Local lysis with alteplase for the treatment of acute embolic leg ischemia following the use of the duett closure device: preliminary results]. / Lokale Alteplase-Lyse zur Therapie der akuten embolischen Beinischämie nach Einsatz des Duett-Verschluss-Systems: vorläufige Ergebnisse.

PURPOSE: To analyze retrospectively the result of the alteplase lysis therapy of embolic complications following the use of the Duett closure device. METHODS AND MATERIALS: For 3.5 years, the Duett closure device was used in 1,398 angiographies to close the femoral puncture site. The Duett device consists of a balloon and a liquid procoagulant containing collagen and thrombin, which is injected into the puncture tract under endovascular balloon protection of the arterial puncture site. In 9 patients (0.64 %), the procoagulant was incidentally injected into the femoral artery causing acute leg ischemia. Eight patients received local lysis therapy with alteplase via a contralateral femoral access. One patient underwent surgery. On average, 21 mg alteplase (4 - 35 mg) were administered within 14 h (4 - 21 h). The course of the lysis was followed angiographically and clinically. All patients were interviewed by telephone 23 months (4 - 35 months) later. RESULTS: In 3 patients, lysis was complete. In 5 patients, only little thrombotic material remained. In all patients, symptoms of ischemia resolved completely within the first hours after initiation of lysis. In 5 cases, bleeding occurred at the puncture site closed with the Duett device during lysis, including development of a false aneurysm in 2 cases. Complications led to premature termination (n = 2) or interruption of the lysis (n = 3). All complications were treated conservatively. Clinically, long-term sequelae were paresthesia and hypoesthesia in the lower leg and foot in 2 patients treated with lysis, and in the patient who underwent surgery. CONCLUSION: Very rarely occurring embolic complications after use of the Duett closure device can be effectively treated with alteplase lysis. A high rate of complications is to be expected at the puncture site closed with the Duett device.

[A novel hirudin coating of vascular endoprostheses: experimental results]. / Eine neuartige Hirudinbeschichtung vaskulärer Endoprothesen: Experimentelle Ergebnisse.

PURPOSE: Does hirudin coating improve the patency of iliac artery endoprostheses in comparison to non-hirudin-coated endoprostheses? MATERIALS AND METHODS: Nitinol stents and stentgrafts covered with polytetrafluoroethylene (PTFE) were coated with the polymer polyamino-p-xylylene-co-poly-p-xylylene using chemical vapor deposition (CVD) technique. Hirudin was covalently bound to the surface of the endoprostheses via the amino-group. External factors (mounting of the prosthesis, sterilization, storage time and temperature, release) affecting the hirudin activity were evaluated in vitro. Five types of prostheses were compared in vivo: (1) plain and (2) CVD- and hirudin-coated stents; (3) plain, (4) CVD-coated, and (5) CVD- and hirudin-coated PTFE-stentgrafts. In 20 sheep, 16 protheses of each type were inserted in arteries pretreated with a Fogarty maneuver. The animals were followed for either 1 (n = 10) or 6 (n = 10) months. Immediately after implantation and after 1, 3, and 6 months, intravascular ultrasound (IVUS) and angiography were performed. The vascular specimens were analyzed histologically. RESULTS: Within 10 weeks, the hirudin activity of coated stents dropped 60 % due to external factors; the activity of coated PTFE stentgrafts dropped 20 %. After 1, 3, and 6 months, IVUS and histology revealed a significantly reduced patency of the hirudin-coated stentgrafts compared to the other prostheses. Only IVUS showed a significantly reduced patency of hirudin coated stents after 1 and 3 months compared to plain and CVD-coated PTFE-stentgrafts. The reduced patency was caused by neointimal hyperplasia. CONCLUSIONS: In an experimental setting, hirudin coating did not improve the patency of vascular endoprostheses.

[Selective CT mesentericography in the diagnostics of obscure overt intestinal bleeding: preliminary results]. / Selektive CT-Mesenterikographie zur Diagnostik schwerer Darmblutungen unklaren Ursprungs: Vorläufige Ergebnisse.

AIM: To evaluate intra-arterial CT mesentericography (CTM) in the diagnostics of severe obscure overt intestinal bleeding in comparison with conventional mesentericography (MG) and surgery. METHODS: In 8 patients (23 - 82 years, mean 59 years), CTM was performed via the catheter left in the superior mesenteric artery after MG to detect the source of bleeding. Early and late-phase spiral CT scans were acquired after administration of contrast medium. Active bleeding was considered to be present if extravasation of contrast medium into the bowel was found. The results of MG and CTM were compared with the results of surgery. RESULTS: With MG active bleeding was found in one patient, with CTM in five patients. In three patients, both MG and CTM were negative. Six patients underwent surgery. Five cases of bleeding detected with CTM were confirmed by surgery. In one case, bleeding found with CTM was not confirmed by surgery. One patient underwent surgery although all imaging procedures were negative. The source of bleeding remained unknown. Surgically, the site of bleeding was located in the jejunum in 3 patients (jejunitis, jejunal ulcers, carcinoid), one patient had a diverticulum in the ascending colon. The colonic bleeding site was correctly localized with CTM, whereas the small bowel bleeding could only roughly be assigned to the proximal or distal jejunum or jejunoileal transition area. CONCLUSION: Preliminary results indicate that selective CTM is superior to MG in the evaluation of severe obscure overt intestinal bleeding.

[Low-grade malignant peripheral nerve sheath tumor of the neck soft tissues]. / Niedrig-maligner peripherer Nervenscheidentumor der Halsweichteile.

BACKGROUND: Malignant Peripheral Nerve Sheath Tumours (MPNST) either grow sporadically, after radiation or chemotherapy respectively. In many cases they are associated with Neurofibromatosis I. Because of the multiform histologic picture they are often difficult to differentiate from other soft tissue tumours. PATIENT: We present the case of a sporadic MPNST which developed from the vagus nerve of a 39-year-old patient following radiation of the neck 7 years before. After complete excision there has been no recurrence up to now. RESULTS AND CONCLUSIONS: Sporadic MPNST of the head and neck are comparatively rare. With regard to the strong association with Neurofibromatosis I and the difficult differential diagnosis to other soft tissue tumours the emphasis should be put on excluding further manifestations of Neurofibromatosis I and of secondary tumours.

[Changes in the region and the proximal aneurysm neck after endovascular repair of infrarenal aortic aneurysms]. / Veränderungen im Bereich des proximalen Aneurysmahalses nach endovaskulärer Ausschaltung infrarenaler Aortenaneurysmen.

PURPOSE: To analyze short and mid-term changes of the proximal aneurysm neck and to evaluate renal function after endovascular repair of infrarenal abdominal aortic aneurysms. MATERIALS AND METHODS: 24 of 29 patients, who were treated endoluminally with the bifurcated Vanguard Stent graft between 1997 and 1999 underwent spiral CT follow-up after 1, 3, 6 and every 12 months. Mean follow-up period was 10.5 months (3-32 months). Follow-up included spiral CT scanning. The aortic diameter as well as cross-sectional area were measured. Stent graft position and renal perfusion were checked by spiral CT. Serum creatinine levels were determined preoperatively and during follow-up. RESULTS: Supra- and infrarenal aortic sizes remained stable. No correlation to the distance between the stent-graft and the renal arteries was observed. Caudal migration of the stent-graft with an average of 6.5 (3-15) mm occurred in 13 patients. Cranial migration was observed in 3 patients. Uncovered stent wires partially overlapped at least one renal artery in 18 patients. No renal infarction occurred. No significant increase of the serum creatinine level was found. CONCLUSION: The risk of proximal endoleakage due to post-interventional dilatation of the aorta abdominalis seems to be low. Insufficient stent graft fixation requires a wide distance between the proximal end of the stent graft and the aneurysm. In the mid-term uncovered stent wires overlapping the renal arteries had no relevant influence on renal function.

[Endoluminal vascular prostheses]. / Endoluminale Gefässprothesen.

Endoluminal vascular prostheses that can be implanted by percutaneous routes represent the most recent development in vascular interventional radiology. Various commercially available types of prosthesis are presented and the construction principles and applications are described. At present secure indications for the implantation of endoluminal prostheses are limited to the elimination of aneurysms and arteriovenous fistulae of the large vessels near the trunk in sections that do not cross a joint. The wide use in peripheral occlusive diseases cannot yet be recommended because confirmed data are not available.

Recanalization of thrombosed dialysis access with use of a rotating mini-pigtail catheter: follow-up study.

PURPOSE: To evaluate the feasibility, efficacy, and safety of mechanical thrombectomy of occluded dialysis access with use of a rotating mini-pigtail catheter. MATERIALS AND METHODS: Thrombus was fragmented by mechanical action of the rotating pigtail tip (5-mm diameter), while the guide wire exited a sidehole at the pigtail curvature and served as a fixed rotation axis. Twenty-six procedures were performed in 22 patients (12 men, 10 women; mean age, 55.5 years). Native fistulas were treated in 15 instances, polytetrafluoroethylene (PTFE) grafts were treated in 11 instances. Average occlusion time was 20 hours +/- 13 (range, 5-46 hours), average occlusion length was 25.6 cm +/- 10.1 (range, 6-45 cm). Thrombus fragmentation was followed by balloon angioplasty of underlying stenoses. RESULTS: In all 26 procedures, the dialysis access was successfully declotted with subsequent dialysis using the access (clinical success rate, 100%). Handling of the mini-pigtail catheter was simple and rapid, regardless of whether a graft or a native fistula was treated. Average duration of the intervention was 118 minutes +/- 30. Mean primary patency was 165 days +/- 167. Primary patency rate was 82% at 30 days, 65% at 3 months, and 47% at 6 months. There was no evidence of complications due to the thrombus fragmentation procedure. CONCLUSION: The results suggest that declotting of occluded dialysis grafts and fistulas with the mini-pigtail catheter is as effective and safe as other more established percutaneous therapies. It may serve as an easy-to-handle, low-budget alternative to current thrombectomy devices.

Suramin inhibits proliferation of human arterial smooth muscle cells in vitro: potential drug for prevention of restenosis by local drug delivery.

PURPOSE: Suramin is known to inhibit proliferation of various tumor cells. This study was performed to investigate the effect of suramin on proliferating human arterial smooth muscle cells (HASMC) and thus to examine its suitability for the prevention of restenosis. METHOD: Proliferation of HASMC was stimulated with human whole blood serum (HWBS), as well as with platelet-derived growth factor (PDGF) and basic fibroblast growth factor (bFGF). Proliferation was assessed by measuring DNA synthesis and cell viability was assessed by measuring mitochondrial activity. RESULTS: Suramin exerted a strong attenuating effect on the proliferation stimulators HWBS, PDGF, and bFGF. A suramin concentration of 0.5 mmol/L, which is approximately twice the dosage used for systemic application, was sufficient for complete neutralization of proliferation stimulation by 10% HWBS added to the cell culture medium. CONCLUSION: The authors' data demonstrate a strong proliferation inhibiting effect of suramin on HASMC in vitro. Because it is known to interact not only with one but with a multitude of relevant growth factors, these results make suramin a most interesting substance for local application for prevention of hyperplastic neointima formation.

[Temporary implantation of a metal stent in Vater's ampulla. Evaluation of early changes of the bile ducts in an animal study]. / Passagere Implantation eines Metallstents in der Papilla Vateri. Beurteilung von Frühveränderungen an der Gallengangswand im Tiermodell.

PURPOSE: Evaluation of temporary stent implantation in the papilla of vater and the subsequent alterations of the bile ducts in a controlled animal study. MATERIAL AND METHODS: In seven domestic pigs the papilla of vater was stented with a nitinolelastalloy-strecker stent over a period of three days. The microscopic and macroscopic changes of the biliary tract and the serologic parameters were judged. RESULTS: In three cases a slight widening of the peripheric bile ducts was found. With the exception of a mild elevation of lactate dehydrogenase the serological parameters remained normal. The explantation of the stent two possible in six cases. A thickening of the outer layers of the bile ducts and a low to middle grade injury of the mucosa were found histologically. CONCLUSION: A temporary stent implantation in the papilla of vater is feasible. The mucosal injuries caused by the temporary stent placement may be fully repairable. The method seems to be suitable for prolonged dilatation of benign stenoses.

Comparison of two stent-grafts with different porosity: in vivo studies in a sheep model.

PURPOSE: To compare two stent-grafts with a polyurethane-carbonate (PUC) polymer lining of different pore size and water permeability in the iliac arteries of sheep. MATERIALS AND METHODS: Two stent-grafts with an inner PUC-lining of normal and low water permeability (normal, 1,200 mL/min/cm2; low, 280 mL/min/cm2; pressure gradient, 20 mm Hg) were implanted in each of 16 sheep. Hoop strength was two times higher in low-permeable than in normal-permeable stent-grafts. Patency was monitored with use of angiography and intravascular ultrasound (IVUS) after 1, 3, and 6 months. The sheep were killed after 1 or 6 months. Specimens were studied histologically. IVUS and histologic data were analyzed statistically. RESULTS: IVUS measurements showed a wider patent lumen of the low- compared to the normal-permeable prostheses at all time points (P < .03). This is likely due to the greater hoop strength of the low-permeable stent-graft. After 1 month, both types of prostheses demonstrated complete transprosthetic tissue penetration and were covered with neointima and endothelium. The neointimal area was greater in low- than in normal-permeable stent-grafts (1 month, P < .005; 6 months, P < .03). CONCLUSIONS: Presumably, the higher permeability of the normal-permeable stent-grafts led to the reduced neointimal area by improving transprosthetic capillary ingrowth and endothelialization.

Percutaneous treatment of thrombosed primary arteriovenous hemodialysis access fistulae.

BACKGROUND: We reviewed the efficacy of percutaneous intervention in acute thrombotic occlusion of native arteriovenous (AV) fistulae for hemodialysis. METHODS: Eight-one percutaneous procedures were performed in 54 patients presenting with a clotted native dialysis fistula. There were 60 cases of a long-segment thrombosis of the fistula. In 20 cases, a small thrombus usually caused by an underlying severe stenosis was observed. A proximal arterial occlusion was seen in one case. Treatment depended on clot size and included balloon dilation (N = 20), mechanical thrombectomy with various devices (N = 58), as well as pharmacomechanical thrombolysis (N = 3). RESULTS: Full restoration of flow was established in 72 cases (88.9%). Early reobstruction within 14 days occurred in eight cases (11.1%). Primary patency rates after a 1-, 3-, 6-, and 12-month period were 74, 63, 52, and 27%, respectively. Overall fistula patency was 75% after 3 months, 65% after 6 months, 51% after 12 months, and 22% after 24 months. CONCLUSIONS: Acute thrombotic occlusion of native AV fistulae is a major complication of hemodialysis. The results of treatment are believed to be less successful than thrombosis treatment in synthetic grafts. Our results, however, indicate the efficacy of percutaneous treatment in native fistulae, and demonstrate comparable technical results and patency rates.

Magnetic resonance angiography of nonferromagnetic iliac 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 x 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.