Aortic Bifurcation Reconstruction: Use of the Memotherm Self-Expanding Nitinol Stent for Stenoses and Occlusions

Purpose: To assess the technical success, initial clinical outcome, and intermediate follow-up of the Memotherm nitinol self-expanding stent in aortic bifurcation reconstruction. Methods: Thirty-three patients (13 male, 20 female), mean age 64 years, were treated, who had symptoms classified by the Surgical Vascular Society/International Society of Cardiovascular Surgery (SVS/ICVS) classification as grade 2 in 11 (33%), grade 3 in 19 (58%) and grade 4 in 3 (9%) patients. Lesions were classified according to severity and type. Indications for placement of a Memotherm nitinol self-expanding stent were failed angioplasty in 14 (42%), chronic occlusions in 12 (37%), and complex stenoses in seven (21%) patients. Results: Sixty-seven stents were technically successfully placed in 66 aorto-iliac segments in 33 patients, with one major complication. Initial clinical outcome was improvement in 25 (81%), no change in four (13%), and a worsening in two (6%) patients by Rutherford criteria. Mean early ankle/brachial pressure index (ABI) gain was 0.27 for occlusions and 0.05 for stenoses. Clinical follow-up was obtained in all patients, with retrospective angiographic follow-up in 28 (85%) at a mean of 16 months (range 12–26 months). The decrease in ABI and the decrease in angiographic luminal diameter at follow-up was determined as the “late loss.” The mean ABI late losses were −0.06, 0.00, and 0.09, and the mean angiographic late losses were 6.7%, 10% and 14% for occlusions, stenoses, and normal segments respectively. Primary clinical patency was 96%, primary angiographic patency was 89%, and secondary angiographic patency was 93%. Conclusion: The high technical success of stent placement, the low complication rates for aortic bifurcation reconstruction using the Memotherm self-expanding stent, and high clinical and angiographic patency maintained at intermediate follow-up support their use in aortic bifurcation reconstruction.     

Aortic bifurcation reconstruction: Use of the memotherm self-expanding nitinol stent for stenoses and occlusions

PURPOSE: To assess the technical success, initial clinical outcome, and intermediate follow-up of the Memotherm nitinol self-expanding stent in aortic bifurcation reconstruction. METHODS: Thirty-three patients (13 male, 20 female), mean age 64 years, were treated, who had symptoms classified by the Surgical Vascular Society/International Society of Cardiovascular Surgery (SVS/ICVS) classification as grade 2 in 11 (33%), grade 3 in 19 (58%) and grade 4 in 3 (9%) patients. Lesions were classified according to severity and type. Indications for placement of a Memotherm nitinol self-expanding stent were failed angioplasty in 14 (42%), chronic occlusions in 12 (37%), and complex stenoses in seven (21%) patients. RESULTS: Sixty-seven stents were technically successfully placed in 66 aorto-iliac segments in 33 patients, with one major complication. Initial clinical outcome was improvement in 25 (81%), no change in four (13%), and a worsening in two (6%) patients by Rutherford criteria. Mean early ankle/brachial pressure index (ABI) gain was 0. 27 for occlusions and 0.05 for stenoses. Clinical follow-up was obtained in all patients, with retrospective angiographic follow-up in 28 (85%) at a mean of 16 months (range 12-26 months). The decrease in ABI and the decrease in angiographic luminal diameter at follow-up was determined as the "late loss." The mean ABI late losses were -0.06, 0.00, and 0.09, and the mean angiographic late losses were 6.7%, 10% and 14% for occlusions, stenoses, and normal segments respectively. Primary clinical patency was 96%, primary angiographic patency was 89%, and secondary angiographic patency was 93%. CONCLUSION: The high technical success of stent placement, the low complication rates for aortic bifurcation reconstruction using the Memotherm self-expanding stent, and high clinical and angiographic patency maintained at intermediate follow-up support their use in aortic bifurcation reconstruction.     

Long-term results 10 years after iliac arterial stent placement

PURPOSE: To retrospectively evaluate results in 110 patients who had iliac arterial occlusive disease and were treated with stents before 1991. MATERIALS AND METHODS: From 1987 to 1990, 110 patients (mean age, 57 years) with iliac arterial occlusive disease (Fontaine stage IIa, seven patients; IIb, 95 patients; III, four patients; IV, four patients) underwent implantation of a self-expanding metal stent. Stenoses (n = 66) were treated after failed angioplasty, and occlusions (n = 60) were treated with primary stent placement. Follow-up included angiography and/or color duplex ultrasonography and clinical examination with ankle-brachial index measurement. Patients lost to follow-up were interviewed by using dedicated questionnaires administered by telephone and/or mail. If a patient was deceased, relatives and attending doctors were interviewed. RESULTS: The fate of 109 of the 110 patients was determined. Overall, 46 patients died: 18 within 5 years, 39 within 10 years, and seven after more than 10 years. The 5- and 10-year survival rates were 83% and 64%, respectively. Cardiovascular disease caused 23 deaths; malignant tumor caused 15. The cause of death remained unknown in five patients. Primary stent patency rates were 66% +/- 4.8 (standard error) after 5 years and 46% +/- 5.9 after 10 years; secondary patency rates were 79% +/- 4.2 after 5 years and 55% +/- 6.3 after 10 years (Kaplan-Meier test). Seventeen (16%) patients underwent surgical bypass of the aortoiliac arteries that involved the segment with the stent, 14 because of stent restenosis and three because of stenosis in other iliac arterial segments. CONCLUSION: The main cause of death in patients with intermittent claudication was cardiac disease. Long-term patency of iliac arterial stents was moderate.     

Lower Extremity Venous Stent Placement: A Large Retrospective Single-Center Analysis

PurposeTo study short-term and long-term outcomes of lower extremity venous stents placed at a single center and to characterize changes in vein diameter achieved by stent placement.Materials and MethodsA database of all patients who received lower extremity venous stents between 1996 and 2018 revealed 1,094 stents were placed in 406 patients (172 men, 234 women; median age, 49 y) in 513 limbs, including patients with iliocaval stents (9.4% acute thrombosis, 65.3% chronic thrombosis, 25.3% nonthrombotic lesions). Primary, primary assisted, and secondary patency rates were assessed for lower extremity venous stents at 1, 3, and 5 years using Kaplan-Meier analyses and summary statistics. Subset analyses and Cox regression were performed to identify risk factors for patency loss. Vein diameters and Villalta scores before and up to 12 months after stent placement were compared. Complication and mortality rates were calculated.ResultsPrimary, primary assisted, and secondary patency rates at 5 years were 57.3%, 77.2%, and 80.9% by Kaplan-Meier methods and 78.6%, 90.3%, and 92.8% by summary statistics. Median follow-up was 199 days (interquartile range, 35.2–712.0 d). Patency rates for the subset of patients (n = 46) with ≥ 5 years of follow-up (mean ± SD 9.1 y ± 3.4) were nearly identical to cohort patency rates at 5 years. Patients with inferior vena cava stent placement (hazard ratio 2.11, P < .0001) or acute thrombosis (hazard ratio 3.65, P < .0001) during the index procedure had significantly increased risk of losing primary patency status. Vein diameters were significantly greater after stent placement. There were no instances of stent fracture, migration, or structural deformities. In patients with chronic deep vein thrombosis, Villalta scores significantly decreased after stent placement (from 15.7 to 7.4, P < .0001). Perioperative mortality was < 1%, and major perioperative complication rate was 3.7%.ConclusionsCavo-ilio-femoral stent placement for venous occlusive disease achieves improvement of vein disease severity scores, increase in treated vein diameters, and satisfactory long-term patency rates.     

Angioplasty and stent placement in chronic occlusion of the superficial femoral artery: technique and results

PURPOSE: To improve the patency rate for angioplasty in chronic occlusion of the superficial femoral artery by deploying stents after angioplasty. MATERIALS AND METHODS: Angioplasty and stent placement were performed in 61 arteries in 48 male patients. The mean occlusion length was 13.5 cm and the mean stent length was 30 cm. Patency rates were analyzed at 6 months and at 1, 2, 3, and 4 years. The predictors of restenosis were analyzed by univariate and multiple logistic regression. RESULTS: Patency rates were 87% at 6 months, consisting of 74% primary, 6% primary assisted, and 7% secondary; 79% at 1 year, consisting of 47% primary, 19% primary assisted, and 13% secondary; 72% at 2 years, consisting of 36% primary, 26% primary assisted, and 10% secondary; 70% at 3 years, consisting of 26% primary, 22% primary assisted, and 22% secondary; and 63% at 4 years, consisting of 25% primary, 0% primary assisted, and 38% secondary. There was a 15% morbidity rate and one mortality as a result of retroperitoneal bleeding. Better patency rates were noted at all time intervals in diabetic limbs, 7-mm-diameter versus 10-mm-diameter stents, shorter obstructions and shorter stents, nonsmokers, in limbs in which urokinase was not necessary after stent deployment, and in limbs with an International Society of Cardiovascular Surgery (ISCVS) classification under 3. Patency rates were not affected by age, race, number of trifurcation vessels patent, experience in performing the procedures, and procedures requiring less time. By multivariate logistic analysis, the independent predictors of patency at 6 months were postprocedure ankle/brachial index (ABI) and shorter stent length; at 1 year, preprocedure ABI, shorter stent length, and the presence of diabetes; at 2 years, preprocedure ABI and the presence of diabetes; and at 3 years, the preprocedure ABI. CONCLUSIONS: The techniques used to reestablish antegrade flow in these superficial femoral arteries yielded a high success rate. In addition, the use of angioplasty with stents may improve patency rates over angioplasty without stents.     

Self-expanding nitinol stents for treatment of infragenicular arteries following unsuccessful balloon angioplasty

The feasibility of self-expanding nitinol stents for treatment of infragenicular arteries following unsuccessful balloon angioplasty was assessed. Options for lower limb percutaneous revascularization are limited, especially for complex vessel obstruction. Depending on the lesion and the experience of the interventionalist, the failure rate of balloon angioplasty (PTA) ranges between 10 and 40%. Until recently, no self-expanding stent for the use in the infragenicular arteries was available. This is the first report of the results for 18 consecutive patients who received 4F sheath compatible self-expanding nitinol stents following unsuccessful PTA or early restenosis. Twenty-four stents were implanted in 21 lesions for various indications residual stenosis >50% due to heavy calcification, flow-limiting dissection, occluding thrombus resistant to thrombolyis, thrombaspiration, and PTA, and early restenosis after previous PTA. Stent implantation was feasible in all cases. No complications occurred. After the stent implantation, all primarily unsuccessful interventions could be transformed into successful procedures with no residual stenosis >30% in any case. After 6 ± 2 months, two of the 18 patients died, and 14 of the 16 remaining patients improved clinically. At follow-up, the patency could be assessed in 14 stented arteries. Three stents were occluded, one stent showed some neointimal hyperplasia (50–70% restenosis), the remaining ten stents showed no restenosis (0–30%). The use of self-expanding nitinol stents in tibioperoneal and popliteal arteries is a safe and feasible option for the treatment of unsuccessful PTA. The 6-months patency is high.     

Outcomes of tracheobronchial stent placement for benign disease

PURPOSE: To retrospectively determine long-term outcomes in patients who have undergone tracheobronchial stent placement for benign diseases. MATERIALS AND METHODS: Institutional Review Board approval was obtained for this retrospective HIPAA-compliant study, with waiver of informed consent. Forty patients (22 female, 18 male; mean age, 52.0 years) who were treated with metallic airway stents for benign stenosis were identified from an interventional radiology database. Causes of airway stenosis included transplant stricture (n = 13), tracheal tube injury (n = 10), inflammation (n = 6), tracheobronchomalacia (n = 4), infection (n = 3), and extrinsic compression (n = 4). Follow-up, which ranged from 6 to 2473 days, was performed by means of chart review for deceased patients and by means of clinical visit or telephone interview for surviving patients. Survival, primary patency, and assisted patency were estimated by using the Kaplan-Meier product limits method. RESULTS: Initial technical success was achieved in all cases. Symptomatic improvement was present in 39 of 40 cases. At review, 15 patients were alive and had clinical improvement, 18 had died of comorbid causes, one had died of uncertain causes, three had undergone subsequent airway surgery, two had undergone airway stent retrieval, and one was lost to follow-up. Survival at 1, 2, 3, 4, 5, and 6 years was 79%, 76%, 51%, 47%, 38%, and 23%, respectively. Loss of primary patency was most rapid during the 1st year. With repeat intervention, assisted patency was 90% at 6.8 years. CONCLUSION: Attrition of tracheobronchial stent patency is most rapid during the 1st year, and a high rate of long-term patency can be achieved with secondary interventions. Metallic airway stents are well-tolerated and useful adjuncts for management of select benign tracheobronchial stenoses.     

Conformation of Adjacent Self-expanding Stents: A Cross-Sectional In Vitro Study

We examined the proximal conformation of three commonly used self-expanding stents when the stents were deployed adjacent to one another in a tubular model, simulating a “kissing” stent technique. The stent pairs were evaluated by computed tomogrphy to determine the cross-sectional area excluded by the stents within the model. The mean areas associated with each stent pair were compared and significance evaluated by a t-test. A statistically significant difference was found when the area excluded by adjacent Wallstents was compared with both the Luminexx and SMART stents (p < 0.001 and p < 0.002, respectively). The difference in the area excluded and differences in conformation might play a role in the lower patencies that have been observed in “kissing” stent series. This work was presented at the Society of Interventional Radiology Annual Scientific Meeting, March 2004, Phoenix AZ.     

Retrospective Comparison of the Patency of Wallstents and Palmaz Long-Medium Stents Used for TIPS

Purpose: To compare patency rates of transjugular intrahepatic portosystemic shunts (TIPS) after placement of long-medium Palmaz stents or Wallstents. Methods: We performed a retrospective review of TIPS performed at our institution between December 1997 and December 1998. During this time period we placed long-medium Palmaz stents for TIPS procedures in 17 patients and Wallstents in 20 patients as the initial stent. Patency was determined on follow-up by ultrasound, angiography, or pathologic examination in the event of transplant. Results: Primary patency in the Palmaz stent group was 70.6% (12/17 patients) (follow-up 1–399 days, mean 127 days). Both primary assisted and secondary patency in the Palmaz group was 100% (17/17 patients) (follow up 1–399 days, mean 154 days). Primary patency in the Wallstent group was 50% (10/20 patients) (follow up 1–370 days, mean 65 days). Primary assisted patency in the Wallstent group was 80% (16/20 patients) (follow up 1–601 days, mean 141 days). Secondary patency in the Wallstent group was 100% (20/20 patients) (follow up 2–601 days, mean 142 days). Kaplan-Meier analysis of the two groups of patients yielded a primary patency of 266 days (standard error 45 days) for TIPS with the Palmaz stent and 139 days (standard error 45 days) for the Wallstent (p = .04). The 3, 6, and 12-month primary patency rates were .84, .63, and .42 respectively for the Palmaz stents and .36, .36, and .18 respectively for the Wallstent. There was no significant difference in primary assisted or secondary patency between the two stent groups. The mean tract curvature in the patients with Palmaz stents was 23.5° (SD 18.2°, range 0–69.0°) compared with 57° (SD 34.5°, range 7.0–144.0°) in patients with Wallstents (p = .01). Conclusions: Our nonprospective, nonrandomized study suggests that TIPS created with the long-medium Palmaz stent have a higher primary patency than those created with the Wallstent in tracts that are relatively straight.     

Below-the-ankle Angioplasty and Stenting for Limb Salvage: Anatomical Considerations and Long-term Outcomes

Purpose

To report the long-term angiographic and clinical results in a series of below-the-ankle (BTA) angioplasty procedures and to present some biomechanical issues related to the unique anatomical geometry of the ankle.

Methods

We performed a retrospective analysis of BTA angioplasty procedures. Clinical end points included technical success, patient mortality, salvage of the treated foot, and repeat target lesion revascularization. Imaging end points included primary patency, binary restenosis of the target lesion at the 50 % threshold, and stent integrity (stent fracture, deformation, or collapse). Univariate subgroup analysis was performed.

Results

In total, 40 limbs in 37 patients (age 73.5 ± 8.2 years) with critical limb ischemia were included and 42 inframalleolar lesions (4.2 ± 1.4 cm) were analyzed. Technical success was achieved in 95.2 % (40 of 42). Provisional stent placement was performed in 45.2 % (19 of 42). Two patients died, and two major amputations occurred up to 3 years. At 1 year, overall primary vessel patency was 50.4 ± 9.1 %, lesion binary restenosis rate was 64.1 ± 8.3 %, and repeat intervention-free survival was 93.6 ± 4.3 % according to life table analysis of all treated lesions. Pairwise subgroup analysis showed that BTA self-expanding stents were associated with significantly higher restenosis and poorer primary patency compared to plain balloon angioplasty or sirolimus-eluting balloon-expandable stents. Significant deformation and/or fracture of balloon-expandable stents placed BTA were identified in five of 11. Dynamic imaging showed that the dorsalis pedis artery is kinked during foot dorsiflexion, whereas the distal posterior tibial artery is kinked during plantar flexion of the foot.

Conclusion

BTA angioplasty for critical limb ischemia treatment is safe and feasible with satisfactory long-term results. BTA stent placement must be reserved for bailout indications.     

Endovascular Treatment of Complex Aneurysms with the Use of Covera Stent Grafts

PurposeTo characterize the short-term results of a newly available self-expanding covered stent (Covera; CR Bard Peripheral Vascular Inc., Murray Hill, New Jersey) for the reconstruction of target vessels in complex aneurysms.Materials and MethodsFrom August 2017 to November 2018, this self-expanding covered stent was used in 17 patients (mean 72.6 ± 7.6 years of age) during endovascular aneurysm repair (EVAR) with hypogastric preservation (11.8%), branched EVAR (29.4%), fenestrated (F)-EVAR (17.6%), chimney + F-EVAR (11.8%), or chimney EVAR (29.4%). In more than 48 stented arteries (2.8 ± 1.1/patient), 25 were preserved using this self-expanding covered stent.ResultsAll target vessels were successfully preserved. There was no 30-day mortality and 1 in-hospital death. Intraoperative aneurysm exclusion was successful in 14 patients (82.4%) with a perioperative technical success rate of 82.4%. The actuarial survival rate was 93.8% at 6 months and 85.9% at 12 months. Aneurysm sac regression of >5 mm was observed in 4 cases (23.5%), and the sac remained stable in the remaining patients (13 cases [76.5%]). At 12 months, the primary clinical success rate was 76.5%, and assisted primary clinical success rate was 82.4%. No type 3 endoleak was related to a disruption of the reconstruction with the self-expanding covered stent.ConclusionsThis new self-expanding covered stent provides good short-term patency in chimneys, branches, or fenestrations. Larger series with long-term follow-up are required to determine if the stent can sustain the mechanical stress to which it will be submitted in these repairs.     

Infrarenal aortic stents: Initial clinical experience and angiographic follow-up

From March 1990 to May 1991, arterial stents were placed in seven patients because of a tight stenosis (five patients) or a total chronic occlusion (two patients) located in the infrarenal aorta. In one case, the aortic occlusion extended to both common iliac arteries. After balloon dilatation, aortic stents were successfully positioned in all cases. Bilateral common iliac recanalization and stent placement were performed in one case. No complications occurred in any of the patients. Follow-up data were derived from clinical assessments and angiographic results. After a 15.1-month mean follow-up period (range 12–24 months), the seven aortic stents remained patent. Three iliac artery procedures were performed in two of the patients as well. Claudication recurred in three of the seven patients which was related to a common iliac occlusion (one case) or distal progression of atherosclerosis (two cases). Aortic stents seem to be suitable for treating failed angioplasty of aortic lesions but the procedure remains technically difficult when there is associated severe atherosclerosis of the proximal common iliac arteries. Nevertheless, considering the morbidity rate (0%) and the patency rate in this series, this technique could become an alternative to surgical treatment for infrarenal aortic occlusive lesions.     

Long-term results of treatment of benign central venous obstructions unrelated to dialysis with expandable Z stents.

PURPOSE: To evaluate long-term patency of self-expanding Z stents for treatment of benign central venous obstructions unrelated to dialysis. MATERIALS AND METHODS: Z stents were placed in 19 patients, (ages 26-72 years) with severe symptomatic obstructions of the superior or inferior venae cavae and their large branches and portal vein caused by surgical or catheter injury (n = 8), fibrosis (n = 5), cirrhosis (n = 3), Budd-Chiari syndrome (n = 2), and extrinsic compression (n = 1). Fourteen patients underwent stent placement primarily, five after local urokinase infusion for superimposed thrombosis. Follow-up was performed with ultrasound and venography. RESULTS: Venous congestive symptoms quickly resolved in all patients after stent placement. The follow-up period was from 1 to 94 months. Twelve patients have died during follow-up from 1 to 37 months although all remained asymptomatic until death. Six patients remain alive, asymptomatic, with patent stents, and with follow-up from 24 to 94 months. Primary patency was 83%, and secondary patency was 100%. One patient with a patent stent at 12 months was lost to follow-up. No stent migrations, perforations, infections, or significant complications occurred. CONCLUSION: Benign central venous obstructions are effectively treated by the placement of self-expandable Z stents. Placed percutaneously into obstructive lesions with a minimum risk, these stents offer long-term durability and patency.     

Efficacy of Covered Metallic Stents in the Treatment of Unresectable Malignant Biliary Obstruction

We evaluated the efficacy of covered stents for malignant biliary obstruction. We studied 62 patients with obstruction distal to the hilar confluence who survived longer than 10 weeks and divided them into a covered stent group (group 1, n = 22), a Z stent group (group 2, n = 19), and a mesh stent group (group 3, n = 21), according to their type of the stent. Patency rates of each group were compared. Early stent revision was required after 3 days in 18% (4/22) of group 1, 26% (5/19) of group 2, and 0% (0/21) of group 3. The 10, 20, and 40-week primary patency rates were 77%, 77%, and 59% (group 1), 42%, 25%, and 8% (group 2), and 76%, 71%, and 55% (group 3), respectively. Primary patency rates of groups 1 and 3 were significantly higher than those of group 2 (p < 0.05), and there was no statistically difference between those of group 1 and group 3. The 10, 20, and 40-week assisted primary (secondary) patency rates were 96%, 96%, and 96% (group 1), 68%, 49%, and 39% (group 2), and 86%, 74%, and 58% (group 3), respectively. Assisted primary patency (secondary) rates of group 1 were significantly higher than those of groups 2 and 3 (p < 0.01 and p < 0.05, respectively). Our study suggests that the primary patency rates of the covered stents are equal to those of mesh stents, but these may be improved further if covered stents, which avoid the need for early revision, are used.     

Treatment of Pelvic Venous Spur (May–Thurner Syndrome) with Self-Expanding Metallic Endoprostheses

Purpose: The application of self-expanding metallic endoprostheses (stents) to treat symptomatic pelvic venous spurs as an alternative to surgery. Methods: Wallstents with a diameter from 14 to 16 mm and one Cragg stent were placed in the left common iliac vein of eight patients (seven women, one man; mean age 42 years) with a symptomatic pelvic venous spur (left deep venous thrombosis or post-thrombotic leg swelling). Four patients had surgical thrombectomy prior to stent placement. Results: Technical success with immediate reduction of left leg circumference was achieved in all eight patients. A primary patency rate of 100% was observed during an average follow-up of 3 years (range 10–121 months). There were no procedural or stent-related complications. Conclusion: The percutaneous transfemoral placement of self-expanding metallic stents is an effective minimally invasive alternative to surgery in the treatment of symptomatic pelvic venous spur. Received: 0/00/00/Accepted: 0/00/00     

Comparison of self-expanding polyethylene terephthalate and metallic stents implanted in porcine iliac arteries

Purpose: Comparison of the biocompatibility of self-expanding polyethylene terephthalate (PET) stents with self-expanding metallic stents (Wallstents). Methods: Diameter- and length-matched PET stents and Wallstents were symmetrically implanted in the paired iliac arteries of 13 crossbred domestic swine. Stent deployment was studied angiographically and with intravascular ultrasound immediately after stent implantation. The angiographic stented lumen diameter was measured using quantitative vessel analysis before, immediately after stenting, and at 6-week follow-up. Cross-section histopathology and area morphometry were performed. Results: Immediately poststenting, intravascular ultrasound revealed proximal dislocation of 5 of the 13 PET stents, whereas all metal stents were firmly embedded at the implantation site. At 6-week follow-up, three of the remaining PET stents were totally or subtotally occluded by organized thrombus, whereas all metal stents were patent. Compared with immediately poststenting, the angiographic lumen diameter within the five remaining PET stents was reduced by 30%, and that of the metallic stents was virtually unaltered (p<0.02). This observation was confirmed by postmortem morphometry, wherein the PET-stented vessel segments a diameter stenosis of 40% was measured vs only 9% in the metallic stents (p<0.0001). Conclusion: PET-stent deployment is difficult to control due to the lack of radiopacity of this stent. PET stents seem to be more thrombogenic and lead to significantly more neointimal proliferation than metallic stents.     

Metallic stent placement for iliac artery occlusive disease

Since 1991, we have performed stent placement for 35 iliac artery lesions in 31 patients. The etiologic diseases were atherosclerotic in 34 patients and traumatic dissection in one. The indications of placement were total occlusion in 3, late restenosis after angioplasty in 5, dissection in 5, and residual stenosis due to inadequate angioplasty in 21. We also performed direct stent placement for one traumatic dissection. The stents used were Wallstents in 10, Palmaz stents in 14, Strecker stents in 9, and Memotherm stents in 2 lesions. Follow-up was performed clinically or angiographically with measurement of the ankle/arm pressure index. Stent placement was successful in all cases, and relief or improvement of symptoms was achieved. The follow-up period ranged from 6-85 months (mean, 37.3 months). Late stent stenosis or occlusion occurred in 6 cases, among which 4 occluded lesions were successfully recanalized by thrombolytic therapy with angioplasty or second stent placement. In total, the primary patency rates were 88% and 77% at two and four years, respectively, while the secondary patency rates were 94% and 94%. In conclusion, metallic stent placement may offer extended application of intravascular treatment for iliac artery occlusive disease, and good long-term patency rates can be expected.     

Long-term patency and clinical outcome of the Viabahn stent-graft for femoropopliteal artery obstructions

PURPOSE: To assess the long-term patency of the Viabahn stent-graft after placement for the treatment of occlusive disease of the femoropopliteal artery (FPA). MATERIALS AND METHODS: Viabahn stent-grafts were placed into 87 limbs in 76 patients for the treatment of atherosclerotic occlusive disease of the FPA. Mean lesion length was 14.2 cm (range, 2.8-40 cm), with 80 of 87 lesions (92%) at least 7 cm in length. Patients were followed by duplex ultrasound (US), resting ankle brachial index (ABI) measurement, and clinical status at 6 months, 1 year, and yearly thereafter for a maximum of 8.5 years. A systolic velocity ratio greater than 2.0 on duplex US anywhere in the FPA was defined as a loss of primary vessel patency. RESULTS: Primary, primary assisted, and secondary vessel patency rates were 76%, 87%, and 93%, respectively, at 1 year and 55%, 67%, and 79%, respectively, at 4 years. Mean resting ABI improved from 0.70 before the procedure to 0.90 as of the most recent follow-up (P<.001). Mean Rutherford-Becker classification improved from 3.4 before the procedure to 0.68 as of the most recent follow-up (P<.001). Eighty-eight percent of limbs showed a maintained improvement in clinical status. Primary patency was independent of lesion length and type but dependent on device diameter (P=.001). The primary vessel patency rate in devices of at least 7 mm (n=21) was 82% at 4 years. No stent fractures were observed despite the use of multiple overlapping stent-grafts in 36.8% of limbs (n=32). CONCLUSIONS: This study demonstrates durable vessel patency to 4 years for long Transatlantic Inter-Society Consensus class C and D lesions treated with the Viabahn stent-graft. Results were independent of lesion length and type but dependent on device diameter. This study helps confirm the durability and clinical utility of this device in the treatment of FPA occlusive disease.     

Self-expanding nitinol stents in the femoropopliteal segment: technique and mid-term results

The purpose of this study was to evaluate the safety and efficacy of self-expanding SMART nitinol stents in patients with chronic limb ischemia (CLI) demonstrating Type B or C TransAtlantic Inter-Society Consensus (TASC) lesions in the femoropopliteal (FP) arterial segment. There were 137 lower limbs in 122 patients with chronic limb ischemia, secondary to TASC A (n = 12) or TASC B,C (n = 125) lesions in the FP artery were treated with Cordis SMART self-expanding nitinol stents. Hemodynamic stent failure occurred with the presence of a greater than 50% stenosis within the stented segment, measured by standard Duplex velocity criteria, obtained at various postintervention intervals. The hemodynamic primary stent patency was calculated by life-table methods from the time of intervention, uninterrupted by hemodynamic stent failure. The mean lesion length was 12.2 cm (range, 4 to 28 cm). The technical success was 98%. Within the follow-up period (mean, 302 days), 24 limbs were diagnosed with hemodynamic stent failure. The hemodynamic primary stent patency rates were 92%, 76%, 66%, and 60% at 6, 12, 18, and 24-months, respectively. These data provide objective evidence that endovascular treatment of FP TASC A, B and C lesions using self-expanding nitinol SMART stents in patients with chronic limb ischemia provides favorable safety and durability outcomes. Further investigation is warranted.     

Malignant biliary obstruction: treatment with self-expandable metallic stents

In a 3-year period, 57 self-expandable metallic biliary stents (Wallstent) were successfully placed in 49 patients with malignant biliary obstruction. Thirty-three of our patients have died. In this group follow-up was 1–12 months with a mean of 4.5 months and stent patency was 1–12 months with a mean of 4.3 months. Sixteen patients are still alive. In this group, follow-up was 2–26 months with a mean of 8.4 months and stent patency was 1–18 months with a mean of 6.8 months. In 4 patients a secondary stent was used due to malpositioning during deployment. In 1 patient bilateral drainage was achieved with two stents. Four patients required 5 reinterventions due to reocclusion, with a reocclusion rate of 9.4 %; 3 of them were treated with secondary metallic stents, 1 with a conventional stent and the remaining 1 with balloon dilatation. Thirty-day mortality rate was 8.1 % and procedure-related mortality was 2 %. Major and minor complication rates were 10 % and 22 %, respectively. Self-expandable metallic stents provide good palliation in patients with malignant biliary obstruction. Correspondence to: M. N. Özmen