Iliac Artery Stent Research Articles

Alterations in wall shear stress predict sites of neointimal hyperplasia after stent implantation in rabbit iliac arteries

Restenosis resulting from neointimal hyperplasia (NH) limits the effectiveness of intravascular stents. Rates of restenosis vary with stent geometry, but whether stents affect spatial and temporal distributions of wall shear stress (WSS) in vivo is unknown. We tested the hypothesis that alterations in spatial WSS after stent implantation predict sites of NH in rabbit iliac arteries. Antegrade iliac artery stent implantation was performed under angiography, and blood flow was measured before casting 14 or 21 days after implantation. Iliac artery blood flow domains were obtained from three-dimensional microfocal X-ray computed tomography imaging and reconstruction of the arterial casts. Indexes of WSS were determined using three-dimensional computational fluid dynamics. Vascular histology was unchanged proximal and distal to the stent. Time-dependent NH was localized within the stented region and was greatest in regions exposed to low WSS and acute elevations in spatial WSS gradients. The lowest values of WSS spatially localized to the stented area of a theoretical artery progressively increased after 14 and 21 days as NH occurred within these regions. This NH abolished spatial disparity in distributions of WSS. The results suggest that stents may introduce spatial alterations in WSS that modulate NH in vivo.

Biodegradable Self-Expanding Poly-L/D-Lactic Acid Vascular Stent:A Pilot Study in Canine and Porcine Iliac Arteries

To report results of an in vivo pilot study to evaluate the biocompatibility and delivery system of a new biodegradable vascular stent and validate the study design. Two self-expanding intravascular stents, a biodegradable poly-D/L-lactic acid (PLA) and a medical stainless steel stent (Wallstent) were implanted in the common iliac arteries of 2 postpuberal female pigs and 3 laboratory-bred beagle dogs. Specimens were harvested after 45 days in the dogs and 32 days in the pigs for histomorphometry of the stented iliac artery segments. Preliminary measurements were made to assess the reliability of the quantitative histomorphometric measurements before final measurements. Histomorphometry analyses showed that mean luminal diameter and area were decreased in the PLA stent group (1.97+/-0.48 mm and 14+/-6.4 mm2, respectively) compared to the control stent group (4.28+/-0.83 mm and 61+/-19 mm2, respectively). The intimal thickness was higher in the PLA stent group (0.65+/-0.07 mm) than in the control group (0.44+/-0.21 mm). The mean injury score was 0.19+/-0.12 in the PLA stent group and 0.78+/-0.39 in the controls. In the PLA stent group, the mean inflammation score was 1.46+/-0.78 compared to 0.58+/-0.40 in the control group. There were no differences observed between the animal models. The PLA stent showed increased neointimal formation and reduced patency during early follow-up. Mechanical properties of the new biodegradable vascular stents are still inadequate, and the stent and the delivery device require modifications. The study methods were assessed as reliable and reproducible.

In vivo intravascular electric impedance spectroscopy using a new catheter with integrated microelectrodes

Interventional techniques are necessary, which allow the characterization of intravascular pathological processes. Electric impedance spectroscopy (EIS) can provide cellular information of biological tissue. We tested the feasibility of intravascular EIS by using a new impedance catheter system with integrated microelectrodes in an experimental animal model. Eighteen stents were implanted into the iliac arteries of female New Zealand White rabbits (n = 11) to induce intimal proliferation. After 14, 28 and 56 days the electric impedance was measured inside and outside of the stented arterial segments by using a balloon catheter with four integrated microelectrodes. The impedance was recorded at a frequency ranging from 1 Hz to 1 MHz. After the measurements, the stents were explanted and histomorphometry was performed. The impedance inside and outside the stent was analysed and compared with the histomorphometric data. Fourteen (n = 6), 28 (n = 5) and 56 (n = 6) days after stent implantation the difference of the electrical impedance between the native and the stented iliac artery segment increased from -924 +/- 715 Ohm to 3689 +/- 1385 Ohm (14 days vs. 28 days; p < 0.05) and 8637 +/- 2881 Ohm (14 days vs. 56 days; p < 0.05), respectively. The increase of the electrical impedance corresponded to an increased neointimal proliferation in the stented arterial segment of 3.6% +/-0.7% after 14 days, 8.4% +/- 4.8% after 28 days (14 days vs. 28 days; p < 0.05) and 10.0% +/- 4.1% after 56 days (14 days vs. 56 days; p < 0.01). Intravascular EIS can be performed by a balloon catheter with integrated microelectrodes and allows the detection of neointimal proliferation after stent implantation.

Iliac Artery Stent Placement: Clinical Experience and Short-term Follow-up Regarding a Self-expanding Nitinol Stent

To evaluate the effectiveness, safety, and short-term patency rates of a self-expandable nitinol stent (JostentSelfX; Abbott Laboratories, Chicago, IL) for treatment of iliac artery stenoses. In a prospective study, 34 chronic iliac artery stenoses were primarily treated in 27 patients (mean age, 61.7 years +/- 9.4) by placement of a JostentSelfX. Handling and visibility of the stent was scored on a 4-point scale. Before stent placement, within 3 days after stent placement and at 6 months follow-up, the clinical history, clinical stage according to the Rutherford classification, and the ankle-brachial index (ABI) were assessed. Intra-arterial digital subtraction angiography including measurement of the mean pressure gradient was performed at the time of stent placement and at 6 months follow-up or in case of recurrence of symptoms. The Wilcoxon signed rank test and Kaplan-Meier method were applied for statistical analysis. The immediate technical success rate was 94%. The clinical success rate immediately after the procedure was 96% and 85% at 6 months follow-up. Stent placement significantly decreased the severity of stenoses as well as the mean pressure gradients and significantly increased the ABI. Handling of the stent was judged good. No misplacement occurred. Foreshortening during deployment was negligible and no stent migration was seen. However, visibility of the stent during fluoroscopy was ranked as moderate to bad. Follow-up at 6 months revealed the cumulative angiographic primary patency rate (<50% restenosis and <10 mm Hg mean pressure gradient) to be 0.96. The evaluated self-expandable nitinol stent is an effective tool in treating iliac artery stenoses. Apart from poor visibility, handling was good. The angiographic patency rate is comparable with data reported in other stent trials.

Long-Term Follow-Up of Iliac Wallstents

We evaluated the long-term results of the iliac artery stent placement for the treatment of patients with intermittent claudication. From November 1988 to December 1998, 303 legs were treated with metal stents in 259 patients with iliac occlusive arterial disease in a follow-up study approved by the institutional review board. Stenoses (n = 162) were treated after failed angioplasty and occlusions (n = 141) were treated with primary stent placement. According to Fontaine's clinical classification of chronic ischemia, 266 (88%) legs presented stage IIB, 14 (5%) stage III, and 23 (7%) stage IV. In all legs, self-expandable stents (Wallstent) were implanted. The patients were followed up with clinical examination, ankle brachial- index examination measurement and intravenous angiography. The data were analyzed using the univariate analysis (Kaplan-Meier method) and multivariate analysis (Cox proportional model). The primary endpoint of the study was the identification of restenosis or reoclusion of the stenting arterial segment and a secondary endpoint that was an identification of the risk factors of restenosis and reoclusion. The mean +/- SD ankle-brachial index pre-, post-procedure, and in the last control was 0.58 +/- 0.18, 0.90 +/- 0.23, and 0.86 +/- 0.24, respectively. Primary cumulative patency rates were 70% +/- 4 after 5 years, and 65% +/- 5 after 7 years, and secondary patency rates were 92% +/- 2 after 5 years, and 87% +/- 4 after 9 years. Immediate complications in the first 24 hours appeared in 12 (4%) legs, thrombosis in 5 legs, 3 legs presented with distal embolism, 2 thrombi at the access site and pseudo aneurysm and artery rupture in 1 leg. A patient died in the first 24 hours. Within 30 days after the procedure seven complications, 3 thromboses and 4 stenosis appeared. During follow-up, 42 (16%) patients died of other causes. The main causes of death were cardiac disease (39%), cerebrovascular disease (15%), cancer (7%), respiratory diseases (4%), and death due to accidents (2%), and other causes (9%). In 24% of the cases there was insufficient information to assign a principal cause of death. Thirty-six patients (13%) were lost to follow-up. Complications arose in 54 (18%) legs due to occlusion of the treated segment (29%), and stenosis due to intimal hyperplasia (27%). Thirteen patients required surgical treatment. Primary and secondary patency mean time was 80 +/- 3.7 and 102 +/- 2.4 months, respectively. We found no significant relation between patency and the quality of run-off, but a small vessel diameter and the female gender were negative predictive factors for failure (proportional hazards model). The use of stents for treatment of iliac artery occlusive disease may be considered an effective method with a low complication rate and acceptable long-term follow-up results.

Diffusion of new technology in health care: The case of aorto-iliac occlusive disease

The objective of the current study was to characterize temporal trends in the treatment of aorto-iliac occlusive disease (AIOD) and the impact of the introduction of less invasive therapy on overall intervention rates. Patients with diagnostic codes for AIOD, and procedure codes for aortofemoral bypass (AFB) or iliac artery angioplasty and stenting were selected from the Nationwide Inpatient Sample for 1996 to 2000. Utilization rates of both intervention types were determined. Outcome variables including in-hospital mortality and duration of stay were assessed. The rate of iliac artery angioplasty and stenting increased 850%, from 0.4 to 3.4 cases per 100,000 adults (P <.001). The rate of AFB declined 15.5%, from 5.8 to 4.9 cases per 100,000 adults (P <.005). Older age, white race, and higher-income patients were more likely to undergo angioplasty and stenting. AFB had a higher mortality rate, longer duration of stay, and higher hospital charges compared to angioplasty and stenting. Iliac artery angioplasty and stenting has rapidly gained a large market share in the treatment of AIOD. Acceptable clinical outcomes have likely lowered the threshold for treatment and contributed to the rapid diffusion of this technology for the treatment of AIOD.

A Comment on the CE Marking of Iliac Artery Stents

A Comment on the CE Marking of Iliac Artery Stents

Antegrade iliac artery stent implantation for the temporal and spatial examination of stent-induced neointimal hyperplasia and alterations in regional fluid dynamics

Introduction Neointimal hyperplasia remains an important problem after stent implantation. Previous investigations examining vascular responses to stent implantation and effects of drugs have used a retrograde deployment approach that may inadvertently alter the local fluid dynamics surrounding the stent. We present a model of antegrade iliac artery stent implantation that facilitates the analysis of stent-induced alterations in neointimal hyperplasia and wall shear stress in vivo. Methods: Stent delivery catheters were inserted through the left carotid artery in anesthetized rabbits ( n=37). Catheters were advanced under fluoroscopic guidance to the distal iliac arteries, where the stent was deployed. Hemotoxylin and eosin (H&E) staining of unstented and stented vascular sections was performed 21 days after implantation. Results: Selective unilateral stent implantation was successful in 32 of 37 rabbits. No histological abnormalities were observed in the aorta, contralateral unstented iliac, or distal femoral arteries. Neointimal hyperplasia was localized to the stented region. Discussion: The model of stent implantation was relatively easy to perform and produced selective neointimal hyperplasia within the stented region without evidence of damage, cellular proliferation, or flow disruption in the surrounding normal arterial vessels. The model will allow detailed examination of the influence of stent implantation on indices of wall shear stress, neointimal hyperplasia, the mechanisms of cellular proliferation in vivo, and their modification by drugs.

Endovascular repair of traumatic descending thoracic aortic disruptions: should endovascular therapy become the gold standard?

Acute arterial disruptions of the thoracic aorta are rare and often lethal. They are most often due to blunt trauma and occur most commonly just distal to the left subclavian artery origin in the setting of multisystem injuries. The very proximal nature of the lesion in survivors makes open surgical repair hazardous, with mortality rates reaching over 20%. Endovascular therapy is a new and attractive option for the treatment of those challenging patients. Since March 2002, 3 patients with blunt and 1 patient with a stable iatrogenic descending aortic injury were successfully treated at this institution. Spiral computed tomography followed by angiography was used for diagnosis. No preexisting aortic pathology was present. Major associated injuries included unstable thoracic spinal fractures, abdominal solid organ injuries, and hip fractures, making the subjects poor surgical candidates. The Talent Endovascular Graft was deployed via open femoral or iliac artery access under fluoroscopic guidance. All 4 patients underwent successful exclusion of their thoracic pseudoaneurysm with use of the Talent endovascular graft. One patient required partial coverage of the left subclavian artery, and a second patient had an iliac artery stent deployed after traversal of an area of stenosis with the delivery system. There were no cardiac, neurologic, pulmonary, or peripheral vascular complications. Acute aortic disruption, with its associated high surgical morbidity and mortality, is an excellent indication for endovascular therapy to improve patient outcomes. More long-term data are needed on repair durability.

Effect of smoking on restenosis during the 1st year after lower-limb endovascular interventions.

To investigate whether smoking has an effect on recurrent lumen narrowing after percutaneous transluminal angioplasty (PTA) or stent placement in lower-limb arteries. A total of 650 patients (median age, 70 years; 389 men) with peripheral artery disease who underwent iliac artery PTA (n = 95), iliac artery stent placement (n = 83), femoropopliteal PTA (n = 406), or femoropopliteal stent placement (n = 66) were selected from a prospective database. Patients were categorized according to their preintervention smoking habits as nonsmokers (n = 352), light smokers (one to nine cigarettes daily) (n = 54), habitual smokers (10-20 cigarettes daily) (n = 82), or heavy smokers (>20 cigarettes daily) (n = 162). Multivariate Cox proportional hazards analysis was used to determine whether there was an association between smoking habits and restenosis (> or =50%) in the treated vessel segment within 1 year after treatment. Cumulative restenosis rates at 6 and 12 months according to patients' smoking habits were 99 and 190 nonsmokers, 18 and 22 light smokers, 16 and 29 habitual smokers, and 26 and 47 heavy smokers, respectively (P <.001). Adjusted hazard ratios for restenosis in smokers compared with nonsmokers were 1.51 (95% CI: 0.92, 2.50) for light smokers, 0.49 (95% CI: 0.28, 0.87) for habitual smokers, and 0.46 (95% CI: 0.30, 0.71) for heavy smokers, indicating a reduced restenosis risk in patients who smoked 10 or more cigarettes daily. These patients had reduced restenosis rates after either iliac (P =.011) or femoropopliteal intervention (P =.009). However, endovascular treatment at a younger age, coronary artery disease, and history of myocardial or cerebrovascular infarction were more frequently found in smokers. Smoking 10 or more cigarettes daily is associated with a reduced rate of intermediate-term restenosis after lower-limb endovascular interventions.

1005-43 The foundation for advanced medical education renal and iliac artery stent training program

1005-43 The foundation for advanced medical education renal and iliac artery stent training program

Liposomal alendronate inhibits systemic innate immunity and reduces in-stent neointimal hyperplasia in rabbits.

Innate immunity is of major importance in vascular repair. The present study evaluated whether systemic and transient depletion of monocytes and macrophages with liposome-encapsulated bisphosphonates inhibits experimental in-stent neointimal formation. Rabbits fed on a hypercholesterolemic diet underwent bilateral iliac artery balloon denudation and stent deployment. Liposomal alendronate (3 or 6 mg/kg) was given concurrently with stenting. Monocyte counts were reduced by >90% 24 to 48 hours after a single injection of liposomal alendronate, returning to basal levels at 6 days. This treatment significantly reduced intimal area at 28 days, from 3.88+/-0.93 to 2.08+/-0.58 and 2.16+/-0.62 mm2. Lumen area was increased from 2.87+/-0.44 to 3.57+/-0.65 and 3.45+/-0.58 mm2, and arterial stenosis was reduced from 58+/-11% to 37+/-8% and 38+/-7% in controls, rabbits treated with 3 mg/kg, and rabbits treated with 6 mg/kg, respectively (mean+/-SD, n=8 rabbits/group, P<0.01 for all 3 parameters). No drug-related adverse effects were observed. Reduction in neointimal formation was associated with reduced arterial macrophage infiltration and proliferation at 6 days and with an equal reduction in intimal macrophage and smooth muscle cell content at 28 days after injury. Conversely, drug regimens ineffective in reducing monocyte levels did not inhibit neointimal formation. Systemic transient depletion of monocytes and macrophages, by a single liposomal bisphosphonates injection concurrent with injury, reduces in-stent neointimal formation and arterial stenosis in hypercholesterolemic rabbits.

Carbon-coated Stents Implanted in Porcine Iliac and Renal Arteries: Histologic and Histomorphometric Study

To test in a pig model the biocompatibility and effectiveness of carbon-coated renal and iliac artery stent systems during implantation procedures and at different follow-up periods. Twenty-two miniature pigs received carbon-coated balloon-expandable stainless-steel stents in their renal and iliac arteries. Animals were killed at 7, 30, or 180 days for evaluation of acute, subacute, and chronic biologic response to the implanted devices. Histologic, histomorphometric, and scanning electron microscopy (SEM) analyses were performed to assess inflammatory reaction, endothelialization process, and neointimal growth. Forty-four iliac stents and 42 renal stents were successfully implanted. Mural thrombi were not observed by angiography or histologic examinations. Histologically, no significant inflammatory reaction was detected: the stents appeared covered by a thin monolayer of endothelial cells even at 7-day follow-up. The neointima showed homogeneous growth and moderate thickness at 30-day and 180-day explantations (0.09 mm +/- 0.06 and 0.15 mm +/- 0.13, respectively, for renal arteries; 0.12 mm +/- 0.04 and 0.21 mm +/- 0.12, respectively, for iliac arteries). Internal and external elastic laminae were intact in 82 of 86 cases (95%) of stent-implanted arteries. Histologic validations were obtained with SEM observations for each follow-up group. This study showed good technical results of deployment of carbon-coated renal and iliac stents and very satisfactory biologic behavior in terms of tissue and hematologic compatibility. The devices do not induce thrombus formation.

Endovascular gamma irradiation of the iliac arteries: 1-year results from a clinical safety and feasibility study.

To estimate safety and feasibility of vascular brachytherapy in iliac arteries. Fourteen patients (11 men; mean age 56.7+/-9.9 years, range 44-81) with occlusive disease in 15 iliac arteries (7 external, 8 common) were treated with balloon dilation followed by irradiation from an iridium 192 source (15 Gy at 3 mm from the inner surface of the artery wall) applied with a PARIS centering catheter and bilateral 10-mm margins. Patients receiving stents for suboptimal angioplasty were prescribed a 6-month course of antiplatelet treatment with ticlopidine. Angiography was routinely scheduled for 6 months after intervention. There were no complications of the angioplasty procedure or EVBT treatment; 7 patients received stents for dissection or residual stenosis. Mean follow-up was 12.4+/-6.0 months. At 6-month angiography, 1 (6.7%) restenosis in a common iliac artery stent was found. Another patient with a common iliac artery stent developed transient lower limb ischemia at 4 months, probably due to temporary suspension of antiplatelet treatment and distal disease. Brachytherapy in the iliac arteries appears to be feasible and safe; longer follow-up in more patients is needed to determine its clinical utility in the prevention of restenosis.

Endovascular Gamma Irradiation of the Iliac Arteries:1-Year Results From a Clinical Safety and Feasibility Study

PURPOSE To estimate safety and feasibility of vascular brachytherapy in iliac arteries. METHODS Fourteen patients (11 men; mean age 56.7+/-9.9 years, range 44-81) with occlusive disease in 15 iliac arteries (7 external, 8 common) were treated with balloon dilation followed by irradiation from an iridium 192 source (15 Gy at 3 mm from the inner surface of the artery wall) applied with a PARIS centering catheter and bilateral 10-mm margins. Patients receiving stents for suboptimal angioplasty were prescribed a 6-month course of antiplatelet treatment with ticlopidine. Angiography was routinely scheduled for 6 months after intervention. RESULTS There were no complications of the angioplasty procedure or EVBT treatment; 7 patients received stents for dissection or residual stenosis. Mean follow-up was 12.4+/-6.0 months. At 6-month angiography, 1 (6.7%) restenosis in a common iliac artery stent was found. Another patient with a common iliac artery stent developed transient lower limb ischemia at 4 months, probably due to temporary suspension of antiplatelet treatment and distal disease. CONCLUSIONS Brachytherapy in the iliac arteries appears to be feasible and safe; longer follow-up in more patients is needed to determine its clinical utility in the prevention of restenosis.

Primary stenting of embolic occlusions in iliac arteries.

To present our experience with the use of primary stenting to treat embolic iliac artery occlusions. Six patients (5 men; mean age 50.6+/-14.1 years range 37-72) underwent primary stenting for embolic occlusions lodged in the common iliac and/or external iliac arteries and were retrospectively evaluated. The probable reason for the embolism was atrial fibrillation in 4 patients and acute myocardial infarction in 2. In 5 patients, an additional embolus was demonstrated in the renal, mesenteric, popliteal, and middle cerebral arteries. Iliac emboli were treated with primary implantation of self-expanding stents followed by very low-pressure balloon dilation. In all cases, primary stenting was technically successful and provided immediate recanalization with elimination or reduction of symptoms. There was no procedure-related complication. During the mean 11-month follow-up (range 1-18), all stented iliac arteries remained patient. One patient died due to cerebral embolism at 21 months. Although this experience is limited, excellent midterm results suggest that primary stenting may be a valuable alternative in the treatment of embolic occlusions of the iliac arteries in selected cases.

Heparin-coated Balloon-expandable Stent Reduces Intimal Hyperplasia in the Iliac Artery in Baboons

To examine the effect of heparin-coated balloon-expandable iliac stent placement on intimal hyperplasia in a baboon model. Balloon-expandable (Palmaz-Schatz) stents were placed in bilateral common iliac arteries in 20 male baboons (mean weight: 8.8 kg). In each animal, a heparin-coated iliac stent was placed on one side and the contralateral iliac artery received an uncoated stent that served as a control. The iliac artery stents were harvested at 30 days (n = 10) and 90 days (n = 10). Arteriography was performed to assess iliac patency and intravascular ultrasonography was used to determine neointimal and luminal areas. Histologic and morphometric analysis and scanning electron microscopy were performed in the stent-implanted iliac arteries. One animal was excluded in the 30-day group because of premature death. In the remaining nine surviving animals, seven control stents (78%) and nine heparin-coated stents (100%) remained patent. Morphometric analysis showed that the iliac arteries with heparin-coated stents had larger luminal areas (17%, P <.05), less neointimal area (26%, P <.05), lower neointima-to-media ratios (32%, P <.05), and equivalent medial areas (P =.92) compared to the control group at 30 days. In contrast, all control and heparin-coated stents were patent (100%) in the 90-day group. In that group, the heparin-coated stent group had less neointimal area (28%, P <.05), lower neointima-to-media ratios (42%, P <.05), and equivalent medial area (P =.92) and luminal area (P =.07) compared to the control group. The data demonstrate that heparin-coated balloon-expandable stents reduce intimal hyperplasia after iliac artery stent placement. This approach may represent a useful strategy for prolonging luminal patency after iliac stent placement.

Metallic Stent Implantation in Patients with Iliac Artery Occlusion: Long-term Patency Rate and Factors Related to Recurrence

Purpose: To determine the long-term patency rate in 68 patients with iliac artery occlusion who underwent metallic stent implantation, and to analyze the factors related to recurrence. Materials and Methods: Sixty-eight patients with occlusive disease of the iliac artery underwent implantation of a self-expandable metallic stent. The clinical symptoms were intermittent claudication (n=48), resting pain (n=11), and gangrene (n=9). Stent patency was determined by follow-up angiography and color Doppler imaging, and the cumulative patency rate using the Kaplan-Meier method. Cox's proportional hazard model was used to analyse recurrence-related factors involving clinical symptoms (Fontaine stage), risk factors, and anatomical factors such as lesion location, length, and the development of collaterals. The duration of followup varied from 1 day to 73 months (mean, 23.8 months). Results: Arterial occlusion recurred in 16 of 68 patients (23.5%), and the cumulative patency rate was as follows: 95.4% at one month, 93.2% at six months, 80.1% at one year, 73.2% at two years, 68.9% at three years, and 62% at five years. According to a statistical analysis of risk factors, the recurrence p=0.04) than in those without it, but in patients who smoked, hypertension, DM, and previous cerebrovascular disease were not statistically significant. With regard to anatomical factors, the recurrent rate for lesions involving the external iliac artery was 6.5 times higher (p=0.02) than for those involving the common iliac artery. Variations in the Fontaine stage were not statistically significant indicators of recurrence. Conclusion: The recurrence rate after implantation of an iliac artery stent is higher in patients with heart disease than in those without it, and higher for occlusive lesions involving the external iliac artery than for those of the common iliac artery.

Predictors for adverse outcome after iliac angioplasty and stenting for limb-threatening ischemia

Objective: The role of iliac artery angioplasty and stenting (IAS) for the treatment of limb-threatening ischemia is not defined. IAS has been used primarily for patients with disabling claudication. Because poorer results have been shown in patients with critical ischemia after iliac artery angioplasty, the purpose of this study was to estimate the influence of risk factors on the outcome of iliac angioplasty and stent placement in patients with limb-threatening ischemia. Methods: During a 5-year period (from 1996 to 2001), 85 iliac angioplasty and stent placement procedures (107 stents) were performed in 31 women and 43 men with limb-threatening ischemia. Patients with claudication were specifically excluded. The criteria prepared by the Ad Hoc Committee on Reporting Standards (Society for Vascular Surgery/International Society for Cardiovascular Surgery) were followed to define the variables. The TransAtlantic InterSociety Consensus classification was used to characterize the type of iliac lesions. Both univariate (Kaplan-Meier [KM]) and multivariate analyses (Cox proportional hazards model) were used to determine the association between variables, cumulative patency, limb salvage, and survival. Results: Indications for iliac angioplasty with stenting were ischemic rest pain (56%) and tissue loss (44%). Primary stenting was performed in 36 patients (42%). Stents were placed selectively after iliac angioplasty mainly for residual stenosis or pressure gradient (43%). Overall, primary stent patency rate was 90% at 1 year, 74% at 3 years, and 69% at 5 years. Primary stent patency rate was significantly reduced in women compared with men (KM, log-rank test, P < .001). Primary patency rates at 1, 3, and 5 years were 79%, 57%, and 38% for women and 92%, 88%, and 88% for men. Primary stent patency rate also was significantly reduced in patients with renal insufficiency (creatinine level, >1.6 mg/dL; KM, log-rank test, P < .001). Cox regression analysis identified female gender (relative risk, 5.1; 95% CI, 1.8 to 7.9; P = .002) and renal insufficiency (relative risk, 6.6; 95% CI, 1.6 to 14.2; P = .01) as independent predictors of decreased primary stent patency. No independent predictors for limb salvage and survival were identified. Conclusion: Women undergoing iliac angioplasty and stenting for limb-threatening ischemia have significantly reduced primary stent patency rates and may need additional procedures to obtain satisfactory clinical improvement and limb salvage. Patients with renal insufficiency and critical ischemia also have reduced primary stent patency rates after IAS. Limb salvage, as shown in this study, is not affected by previous iliac stent failure. (J Vasc Surg 2002;36:507-13.)

Sustained reduction of in-stent neointimal growth with the use of a novel systemic nanoparticle paclitaxel.

Paclitaxel (PXL)-eluting stents in animals cause incomplete healing and, in some instances, a lack of sustained suppression of neointimal growth. The present study tested the efficacy of a novel systemic delivery nanoparticle PXL for reducing in-stent restenosis. A saline-reconstituted formulation of PXL stabilized by albumin nanoparticles (nPXL) was tested in 38 New Zealand White rabbits receiving bilateral iliac artery stents. Doses of nPXL (1.0 to 5.0 mg/kg) were administered as a 10-minute intra-arterial infusion; control animals received vehicle (0.9% normal saline). In a follow-up chronic experiment, nPXL 5.0 mg/kg was given at stenting with or without an intravenous 3.5-mg/kg repeat nPXL dose at 28 days; these studies were terminated at 3 months. At 28 days, mean neointimal thickness was reduced (P< or =0.02) by doses of nPXL > or =2.5 mg/kg with evidence of delayed healing. The efficacy of a single dose of nPXL 5.0 mg/kg, however, was lost by 90 days. In contrast, a second repeat dose of nPXL 3.5 mg/kg given 28 days after stenting resulted in sustained suppression of neointimal thickness at 90 days (P< or =0.009 versus single dose nPXL 5.0 mg/kg and controls) with nearly complete neointimal healing. Although systemic nPXL reduces neointimal growth at 28 days, a single repeat dose was required for sustained neointimal suppression. Thus, this novel systemic formulation of PXL may allow adjustment of dose at the stent treatment site and prove to be a useful adjunct for the clinical prevention of in-stent restenosis.