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.     

The strecker stent: Indications and results in iliac and femoropopliteal arteries

We have implanted more than 100 Strecker stents in the iliac and femoral arteries. In iliac arteries, follow-up is available from 8 to 48 months (mean 20 months) and in peripheral arteries, from 8 to 32 months (mean 19 months). In iliac and proximal femoral arteries there was a patency rate of 98% (mean 20 months after stent implantation) whereas in peripheral arteries the patency rate was 70.8% (mean 19 months after stent implantation). Besides careful selection of patients, anticoagulation is very important for successful stenting. Because of the excellent results of stents in iliac vessels there is a wide range of good indications, including primary stenting after recanalization of occlusions. In contrast, stent implantation in peripheral vessels should be restricted to special cases such as acute dissection or reocclusion after successful recanalization.     

Hemodynamics and wall mechanics of a compliance matching stent: in vitro and in vivo analysis.

PURPOSE: Evidence is emerging that the abrupt compliance mismatch that exists at the junction between the stent ends and the host arterial wall disturbs both the vascular hemodynamics and the natural wall stress distribution. These stent-induced alterations are greatly reduced by smoothing the compliance mismatch between the stent and host vessel. A stent that provides this smooth transition in compliance, the compliance matching stent (CMS), has been developed. This study attempts to evaluate the hemodynamics and wall mechanical consequences of the CMS both in vitro and in vivo. MATERIALS AND METHODS: Finite element analysis was used to assess the solid mechanical behavior (compliance and stress) of the CMS in a stent/artery hybrid structure. A similar analysis was performed with a Palmaz stent. In vivo hemodynamics and wall mechanical changes induced by the CMS were investigated in a swine model from direct measurements of flow, pressure, diameter, and histology in the stented segment of superficial femoral arteries after 7 days. RESULTS: Finite element analysis showed that the abrupt compliance mismatch was substantially smoothed between the vessel portions with and without the stent with CMS segments. Circumferential stress was also markedly reduced with the CMS compared to other stent. The in vivo results showed that the CMS was efficient in compliance matching and did not dampen flow or pressure waves downstream the stent. Concurrent histology showed limited thrombus and inflammatory cell accumulation around the stent struts. CONCLUSION: These results indicate that the stent/artery hybrid structure can be compliance matched with proper stent design and that this structure limits solid mechanical stress and hemodynamic disturbances. It remains to be seen whether compliance-matched vascular stents reduce in-stent restenosis.     

Changes in wall mechanics after endovascular stenting in the rabbit aorta: comparison of three stent designs

OBJECTIVE: The aim of this study was to evaluate changes in the wall mechanics of small-diameter arteries after endovascular placement of three different stents. SUBJECTS AND METHODS: Five self-expandable stents (Wallstent), five balloon-expandable noncovered Palmaz stents, and three balloon-expandable covered stents (Jostent) were placed in the infrarenal aorta of 13 New Zealand white rabbits. Systolic blood pressure changes, blood-flow velocity, systolic diameter, and diameter changes were measured and used to calculate the diameter compliance, the distensibility coefficient, and the pulsatility index. RESULTS: Compliance (10(-3) mm kPa(-1)) was 75.3 +/- 20.1 before stenting and reached 94.7 +/- 42.2 upstream, 38.8 +/- 14.2 at the stent level (p < 0.05), and 70.8 +/- 23.2 downstream from the stent. Distensibility (10(-3) kPa(-1)) was 24.3 +/- 6.3 before stenting and reached 27.8 +/- 10.3 upstream, 10.5 +/- 4.4 at the stent level (p < 0.001), and 21.9 +/- 8.6 downstream from the stent. Compliance and distensibility were significantly lower at the stent level than upstream and downstream (p < 0.05). Aortic diameter increased significantly at the stent level from 3.11 +/- 0.40 mm before to 3.76 +/- 0.42 mm after stenting. No significant difference was found among the three stent designs for all the studied data. CONCLUSION: Regardless of the three tested stent designs, endovascular stenting produces a significant decrease in arterial wall compliance of the rabbit aorta.     

Dutch iliac stent trial: long-term results in patients randomized for primary or selective stent placement

PURPOSE: To determine long-term results of the prospective Dutch Iliac Stent Trial. MATERIALS AND METHODS: The study protocol was approved by local institutional review boards. All patients gave written informed consent. Two hundred seventy-nine patients (201 men, 78 women; mean age, 58 years) with iliac artery disease were randomly assigned to undergo primary stent placement (143 patients) or percutaneous transluminal angioplasty (PTA) with selective stent placement in cases in which the residual mean pressure gradient was greater than 10 mm Hg across the treated site (136 patients). Before and at 3, 12, and 24 months and 5-8 years after treatment, all patients underwent assessment, which included duplex ultrasonography (US), ankle-brachial index (ABI) measurement, Fontaine classification of symptoms, and completion of the Rand 36-Item Health survey for quality-of-life assessment. Treatment was considered successful for symptoms if symptoms increased at least one Fontaine grade, for ABI if ABI increased more than 0.10, for patency if peak systolic velocity ratio at duplex US was less than 2.5, and for quality of life if the RAND 36-Item Health Survey score increased more than 15 points. Effects of both treatments on symptoms, quality of life, patency, and ABI were compared by using survival analyses. RESULTS: Patients who underwent PTA and selective stent placement had better improvement of symptoms (hazard ratio [HR], 0.8; 95% confidence limits [CLs]: 0.6, 1.0) than did patients treated with primary stent placement, whereas ABI (HR, 0.9; 95% CLs: 0.7, 1.3), iliac patency (HR, 1.3; 95% CLs: 0.8, 2.1), and score for quality of life for nine survey dimensions did not support a difference between treatment groups. CONCLUSION: Patients treated with PTA and selective stent placement in the iliac artery had a better outcome for symptomatic success compared with patients treated with primary stent placement, whereas data about iliac patency, ABI, and quality of life did not support a difference between groups.     

Femoropopliteal stent placement: long-term results.

Twenty-one patients who underwent percutaneous transluminal angioplasty (PTA) followed by attempted insertion of a self-expandable vascular endoprosthesis for femoropopliteal lesions were prospectively followed up for an average of 17.6 months with angiographic, Doppler ultrasound, and clinical examinations. Stents were placed bilaterally in one patient. Of the 22 lesions, 18 were total occlusions and four, stenoses. Stent placement was successful in 21 of 22 lesions. Nine occlusions occurred: four in the first 30 days and five 1-5 months after PTA. Three patients developed intrastent intimal hyperplasia that necessitated an additional percutaneous procedure. At 12 months, the patency rate without other interventions (the primary patency rate) was 49%. In patients who underwent secondary intervention (fibrinolysis, atherectomy, or PTA), the secondary patency rate was 67%, which fell to 56% after 18 months. At the end of the study, the overall rate of reocclusion was 43%. It is concluded that use of the self-expandable vascular endoprosthesis in the femoropopliteal region likely does not decrease the reocclusion rate after PTA alone. Its use is indicated for treatment of acute closures after femoropopliteal PTA.     

Effects of nitinol Strecker stent placement on vascular response in normal and stenotic porcine iliac arteries

PURPOSE: This experimental study was conducted to evaluate neointimal thickness, lumen diameters, and histologic changes in normal and stenotic porcine iliac arteries following placement of self-expanding nitinol Strecker stents. MATERIALS AND METHODS: Neointimal trauma causing slight vascular stenosis was induced unilaterally within external iliac arteries of 12 swines by means of endothelial abrasion and high cholesterol diet. Nitinol Strecker stents were placed within the stenotic and the normal contralateral vascular segments. For histopathologic evaluation, the pigs were killed 12 or 24 weeks after stent placement and luminal diamters were evaluated angiographically. RESULTS: Excluding one occlusion, 15% narrowing of the lumen diameter was induced unilaterally (P = .002). Initial luminal gain after stent placement was greater for stenotic than for normal arteries. The amount of neointima thickness was not different between stenotic and normal vessels (P > .05). Comparing vascular diameters before stent placement and at follow-up, luminal loss due to neointima proliferation was 22% within normal arteries (P = .0002), while a luminal gain by 15% was found within the stenotic arteries (P = .008). Maturation of neointima and endothelial coverage were complete after 24 weeks. CONCLUSIONS: Even though nitinol Strecker stents induce excessive neointimal proliferation, stenotic arteries seem to profit from great early luminal gain resulting in 15% of vascular expansion at follow-up while slight stenosis is induced within normal iliac arteries.     

Acute changes in aortic wall mechanical properties after stent placement in rabbits

PURPOSE: To evaluate mechanical property changes after endovascular stent placement in small-diameter arteries. MATERIALS AND METHODS: Self-expanding stents (Wallstent) were placed in the infrarenal aorta of five New Zealand White rabbits via a surgical right femoral approach. Blood pressure changes (deltaP) were monitored in the aorta. Blood flow velocity was measured with a 20-MHz, pulsed Doppler probe (n = 4) to calculate the pulsatility index. Aortic diameter (dA) and diameter changes (delta(d)) were measured with a 20-MHz probe in echo-tracking mode. Diameter compliance (Cd) and distensibility coefficient (DC) were calculated as Cd = 2(delta)d/(delta)P and DC = 2delta(d)/delta(P)/dA. RESULTS: Aortic diameter increased from 3.360 +/- 0.4033 mm to 4.020 +/- 0.3033 mm after stent placement at the stent level only. Compliance decreased from 77.644 +/- 24.306 mm kPa(-1) to 31.150 +/-8.245 x 10(-3) mm kPa(-1) at the stent level, and was then significantly lower than upstream (98.500 +/- 53.196 mm kPa(-1)) and down-stream (59.047 +/- 13.833 mm kPa(-1)). There was no significant change in pulsatility index. CONCLUSIONS: Endovascular stent placement produces a significant decrease in arterial wall compliance of the rabbit abdominal aorta.     

MR imaging-guided stent placement in iliac arterial stenoses: a feasibility study

PURPOSE: To assess the feasibility of magnetic resonance (MR) imaging-guided stent placement in iliac arterial stenoses. MATERIALS AND METHODS: Thirteen patients with 14 iliac arterial stenoses were examined prospectively. Angioplasty was performed through a femoral sheath by using a conventional 1.5-T MR imaging system. Stents and catheters were visualized on the basis of their artifacts. Nitinol stents were placed with gradient-echo MR imaging guidance. Angioplasty balloons were inflated with gadolinium-based contrast material. Results were evaluated clinically and with both digital subtraction angiography (DSA) and contrast material-enhanced MR angiography. RESULTS: Ten of 13 patients were treated with technical success by using MR imaging-guided intervention alone. Three patients were treated with additional fluoroscopic guidance, because complications (ie, panic attack, subintimal recanalization, and stent misplacement) occurred with MR guidance. The quality of the postinterventional contrast-enhanced MR angiograms of three of 12 lesions with stents was limited owing to stent-induced signal loss of the lumen. The mean stenosis degree after stent placement was significantly higher at contrast-enhanced MR angiography than at DSA (24.6% vs 6.2%). The mean MR imaging-guided procedure time was 74 minutes. CONCLUSION: MR imaging-guided stent placement in iliac arteries is feasible in select patients. The presented technique has limitations-that is, long procedure times, lack of real-time monitoring, and stent artifacts-that necessitate further modifications before it can be recommended for clinical use.     

Follow-up results after stent placement in failing arteriovenous shunts: A three-year experience

Self-expandable endoprostheses were used in 18 failing arteriovenous shunts after unsuccessful balloon dilatation. Technical success was satisfactory with an early patency in 17 of 18 shunts. Thrombosis right after stenting occurred in three shunts but was successfully treated in two. Followup history revealed recurrent events of reobstruction due either to stent or shunt stenoses or thrombosis. Restenosis within the stented segment was responsible for reobstruction in about half the cases. Although patency was low with 27% at 18-month follow-up, repeated intervention established a shunt survival rate of 77% at 18-month follow-up. Stent placement in AV shunts is useful for overcoming acute problems of balloon dilatation but does not prevent restenosis.     

Stenting of the iliac arteries with the palmaz stent: Experience from a multicenter trial

Balloon-expandable, intraluminal stenting of the iliac arteries with the Palmaz stent was the subject of a multicenter study for 4 years. A total of 486 patients underwent 587 procedures. Four hundred and five patients had unilateral and 81 had bilateral iliac stent placements. Follow-up ranged from 1 to 48 months (mean 13.3±11 months). Sustained clinical benefit of the treated patients was obtained in 90.9% at 1 year, 84.1% at 2 years, and 68.6% at 43 months. Angiographic patency rate was 92%. Diabetes mellitus and poor runoff had significant negative influence on the clinical outcome. The 10% incidence of procedural complications was not altered by operator experience.     

Carotid arterial stent placement: results and follow-up in 53 patients

PURPOSE: To describe the results, complications, and follow-up data after stent placement for occlusive internal carotid arterial disease and to compare the results with those in the literature. MATERIALS AND METHODS: Carotid arterial stent placement was attempted in 57 arteries in 53 patients. Thirty-six (68%) of 53 patients were symptomatic. Forty-two (79%) of 53 patients had one to three clinically important comorbidities and were considered at high risk. All patients underwent pre- and postprocedural independent neurologic examinations. Follow-up consisted of serial duplex ultrasonography and clinical assessment. RESULTS: The immediate technical success rate of stent deployment was 97%. Periprocedurally, three (three [5%] of 57 interventions) transient ischemic attacks and three (three [5%] of 57 interventions) minor strokes occurred. Two deaths occurred in the first 30 days (one myocardial infarction, one renal failure). One ipsilateral major stroke occurred 3 weeks after the procedure. The 30-day ipsilateral major stroke and death rate was 5% (three of 57 interventions). At 30 days, one of three patients with minor stroke had mild residual dysphasia. Treatment remained clinically successful in 48 (96%) of 50 patients. The restenosis rate was 4% (two patients). CONCLUSION: Carotid arterial stent placement in a high-risk population has morbidity and mortality rates comparable to those of carotid endarterectomy in a lower risk population. Carotid arterial stent placement can be performed with a low restenosis rate.     

Stent placement in short unilateral iliac occlusion. Technique and 24-month results

Purpose: To determine the success rate and 24-month follow-up results of primary stent implantation for reconstruction of unilateral short iliac occlusion involving the aortic bifurcation.Material and Methods: In 90 patients attempts of percutaneous transluminal recanalization of a short unilateral occlusion of the iliac arteries were performed. In 72/90 patients, the treatment was successful. Stent implantation was performed after recanalization in all 72 patients. Pre-interventional angiography of successfully treated patients showed unilateral occlusions and contralateral stenosis in 34/72 patients. In 38/72 patients unilateral occlusion without contralateral stenosis was diagnosed. The recanalization of the common iliac artery obstructions were performed with a guidewire and excimer laser angioplasty. Totally 152 stents were used for the treatment of iliac occlusion. Standardized treadmill testing and color-coded Doppler ultrasound were performed before treatment and during the follow-up.Results: In all patients, stents were placed successfully; 5 major and 7 minor complications were observed. A clinical improvement of +2 to +3 according to the American Heart Association criteria was observed in 62 and 10 patients, respectively. Angiographic control was performed after 1-30 months. The primary angiographic patency rate was 83.1%. Angiography revealed significant restenoses in 4 patients successfully treated with transluminal angioplasty, and re-occlusion in 6 patients which were referred to surgery. The patency rate after 24 months was 90.0%.Conclusion: Primary stent implantation is an effective treatment for short iliac obstructions and represents a true endovascular alternative to surgery.