Fracture of popliteal artery stents

Twelve-Month Outcomes of Intravascular Lithotripsy for Treatment of Calcified Popliteal and Infrapopliteal Lesions in Patients With Chronic Limb-Threatening Ischemia

PURPOSE

Vessel calcification is estimated to be present in 30% to 50% of patients with peripheral arterial disease (PAD) and is one of the main challenges in endovascular treatment. The popliteal artery is unique compared with other arteries due to its exposure to significant deformation and biomechanical stress during knee motion. Intravascular lithotripsy (IVL) is a novel technique that uses acoustic pressure waves to cause microfractures within the intimal and medial wall calcification. Intravascular lithotripsy is safe in femoropopliteal and infrapopliteal lesions, but follow-up studies are lacking. Therefore, the purpose of this study was to describe the first follow-up outcomes of IVL in popliteal and infrapopliteal arterial disease.

METHODS

This prospective, multicenter cohort study included all patients treated with IVL in the popliteal and infrapopliteal arteries at 4 sites. Standardized follow-up with duplex ultrasonography was scheduled at 6 to 8 weeks and 12 months. The primary safety endpoint was a composite of major adverse events (MAEs) at 30 days. Primary efficacy endpoints were primary patency, limb salvage, and amputation-free survival (AFS) at 12 months. Secondary endpoints were primary-assisted patency and freedom from target lesion revascularization (TLR). Endpoints were distributed for patients with chronic limb-threatening ischemia (CLTI) and intermittent claudication (IC) and estimated using the Kaplan-Meier method.

RESULTS

Between April 2021 and March 2023, 29 patients with 30 limbs were treated. Diabetes mellitus (DM) and CLTI were present in 62.1% and 80.0% of patients, respectively. Within the 32 treated lesions, severe calcification was present in 84.4% and bailout stenting was necessary in 12.5% of the lesions. Four MAEs occurred within 30 days: 1 closure device failure, 1 major amputation, and 2 deaths, neither of which was related to the study device. The primary patency, primary-assisted patency, freedom from TLR, limb salvage, and AFS at 12 months were 68.8%, 90.0%, 93.3%, 83.9%, and 57.1% for CLTI patients, respectively. No events occurred in restenosis, re-occlusion, TLR, major amputation, or mortality in patients with IC.

CONCLUSIONS

This first-ever analysis on follow-up outcomes of IVL in the popliteal and infrapopliteal arteries demonstrated promising safety and efficacy outcomes with a low rate of bailout stenting.

CLINICAL IMPACT

Vessel calcification is a common feature in peripheral arterial disease (PAD) and is one of the main challenges in endovascular treatment. The popliteal artery is subjected to biomechanical stress during knee motion, which makes stenting unappealing and often leads to worse clinical outcomes. This study aimed to describe the first follow-up outcomes of IVL in popliteal and infrapopliteal arterial disease. As in line with previous studies, no relevant procedural complications were found and the rate of bail-out stenting was only 12.5%. Moreover, in a complex patient population, this study demonstrated promising safety and efficacy outcomes. The comparison of IVL with angioplasty alone or other vessel preparation devices for popliteal and infrapopliteal arterial disease is warranted.

Acute ischemia secondary to popliteal artery stent fracture and embolization

Femoropopliteal disease comprises more than one half of lesions in peripheral vascular disease. The treatment modalities for stenosis or occlusion of this anatomic region include femoropopliteal bypass and percutaneous transluminal angioplasty with or without stenting. Our patient developed acute leg ischemia 3 years after stenting, secondary to stent fracture, with distal embolization of stent fragments. Using mechanical thromboembolectomy and superficial femoral artery to below-the-knee popliteal in situ saphenous vein bypass, we were able to restore perfusion to the limb and retrieve fragments of the fractured stent.

Antecubital perforating vein stent-grafting for radiocephalic arteriovenous fistula recovery: A case report

Stent-grafts have been increasingly used in hemodialysis arteriovenous accesses, particularly in recurrent stenosis or in cases of vein rupture after percutaneous transluminal angioplasty (PTA). Although they limit neointimal hyperplasia, stenosis development at stent edges remains a concern. Despite their advantages, they are seldom used on the forearm veins due to fracture risk associated with elbow motion and the potential to limit cannulation sites. This report presents a novel application of stent-grafts in salvaging a radio-cephalic arteriovenous fistula in an 84-year-old male to treat a single outflow path at the elbow through a stenosed antecubital perforating vein, after failed PTA. The vascular access remained patent 18 months after the procedure, with no need for additional treatments at this target lesion, even though a PTA was required for juxta-anastomotic stenosis. This report highlights a possible further use of covered stents in arteriovenous vascular accesses.

Effects of Tapered-Strut Design on Fatigue Life Enhancement of Peripheral Stents

Peripheral stent could fracture from cyclic loadings as a result of our blood pressures or daily activities. Fatigue performance has therefore become a key issue for peripheral stent design. A simple yet powerful tapered-strut design concept for fatigue life enhancement was investigated. This concept is to move the stress concentration away from the crown and re-distribute the stresses along the strut by narrowing the strut geometry. Finite element analysis was performed to evaluate the stent fatigue performance under various conditions consistent with the current clinical practice. Thirty stent prototypes were manufactured in-house by laser with a series of post-laser treatments, followed by the validation of bench fatigue tests for proof of concept. FEA simulation results show that the fatigue safety factor of the 40% tapered-strut design increased by 4.2 times that of a standard counterpart, which was validated by bench tests with 6.6-times and 5.9-times fatigue enhancement at room temperature and body temperature, respectively. Bench fatigue test results agreed very well with the increasing trend predicted by FEA simulation. The effects of the tapered-strut design were significant and could be considered as an option for fatigue optimization of future stent designs.

Outcomes of popliteal stent-graft placement at the artery hinge point for popliteal artery aneurysm

OBJECTIVES

to assess whether stent-grafts crossing the hinge point (HP) in the popliteal artery are associated with increased complications and decreased patency rates, after endovascular treatment of the popliteal artery aneurysm.

METHODS

This was a single-center, case-control study. Patients were allocated to either the HP group (subjects with stent-grafts crossing the HP) or the control group (subjects with stent-grafts above and/or below the HP) based on stent-graft location in the femoropopliteal artery. HP was defined as the main curve in the popliteal artery in the most acute angle toward the femur that appeared during knee flexion, which was identified by reviewing post-operative angiograms. Independent, blinded reviews were performed for all imaging data. Graft evaluation by CTA or duplex ultrasound was performed at 1, 3, 6, and 12 months and annually thereafter. Outcomes measured included: stent-graft patency, stent-graft fracture, other stent-related complications, and major adverse events, including reintervention, death, amputation, stroke, and myocardial infarction.

RESULTS

A total of 44 limbs treated with placement of heparin-bonded Viabahn endoprostheses were included in this study. Twenty and Twenty Four patients were allocated to the HP group and the control group, respectively. Primary patency rates of the HP group at 1, 2, 3, and 5 years were 84.1±8.4%, 84.1±8.4%, 84.1±8.4%, and 72.1±13.3%, respectively. The primary patency rates of the control group were 87.0±7.0%, 82.4±8.0%, 82.4±8.0%, and 82.4±8.0%, respectively. There was no significant difference between the two groups (P=0.81). No reintervention was performed in the control group. In the HP group, 5 limbs (25.0%) developed endoleak, 3 (15.0%) developed thrombosis, and one (5.0%) developed a stent fracture followed by thrombosis. Thrombosis occurred in 2 limbs (8.3%) of the control group, and stent-graft migration was observed in another 2 cases (8.3%). Neither group demonstrated stent-graft infection or acute popliteal artery embolism. Overall, incidence of stent-related complications were significantly higher in the HP group (P=0.04). Event-free survival rates of the HP group at 1, 2, 3, and 5 years were 75.0±9.7%, 69.6±10.4%, 61.9±11.8%, and 29.0±12.8%, respectively. Corresponding rates in the control group were 79.2±8.3%, 79.2±8.3%, 79.2±8.3%, and 79.2±8.3%, respectively. The difference was not statistically significant between the two groups (P=0.20) CONCLUSIONS: crossing the HP with femoropopliteal artery stent-grafts increased the risk of stent-related complications and reinterventions but did not decrease stent patency or event-free survival.

A computational study of fatigue resistance of nitinol stents subjected to walk-induced femoropopliteal artery motion

Fatigue resistance of nitinol stents implanted in femoropopliteal arteries is a critical issue because of their harsh biomechanical environment. Limb flexions due to daily walk expose the femoropopliteal arteries and, subsequently, the implanted stents to large cyclic deformations, which may lead to fatigue failure of the smart self-expandable stents. For the first time, this paper utilised the up-to-date measurements of walk-induced motion of a human femoropopliteal artery to investigate the fatigue behaviour of nitinol stent after implantation. The study was carried out by modelling the processes of angioplasty, stent crimping, self-expansion and deformation under diastolic-systolic blood pressure, repetitive bending, torsion and axial compression as well as their combination. The highest risk of fatigue failure of the nitinol stent occurs under a combined loading condition, with the bending contributing the most, followed by compression and torsion. The pulsatile blood pressure alone hardly causes any fatigue failure of the stent. The work is significant for understanding and improving the fatigue performance of nitinol stents through innovative design and procedural optimisation.

Toward Data-Driven Learning Healthcare Systems in Interventional Radiology: Implementation to Evaluate Venous Stent Patency

We developed a code and data-driven system (learning healthcare system) for gleaning actionable clinical insight from interventional radiology (IR) data. To this end, we constructed a workflow for the collection, processing and analysis of electronic health record (EHR), imaging, and cancer registry data for a cohort of interventional radiology patients seen in the IR Clinic at our institution over a more than 20-year period. As part of this pipeline, we created a database in REDCap (VITAL) to store raw data, as collected by a team of clinical investigators and the Data Coordinating Center at our university. We developed a single, universal pre-processing codebank for our VITAL data in R; in addition, we also wrote widely extendable and easily modifiable analysis code in R that presents results from summary statistics, statistical tests, visualizations, Kaplan-Meier analyses, and Cox proportional hazard modeling, among other analysis techniques. We present our findings for a test case of supra versus infra-inguinal ligament stenting. The developed pre-processing and analysis pipelines were memory and speed-efficient, with both pipelines running in less than 2 min. Three different supra-inguinal ligament veins had a statistically significant improvement in vein diameters post-stenting versus pre-stenting, while no infra-inguinal ligament veins had a statistically significant improvement (due either to an insufficient sample size or a non-significant p value). However, infra-inguinal ligament stenting was not associated with worse restenosis or patency outcomes in either a univariate (summary-statistics and Kaplan-Meier based) or multivariate (Cox proportional hazard model based) analysis.

Fracture of a popliteal nitinol stent and pseudoaneurysm: a case report and review of the literature

There is a lack of reports onr stent fracture with pseudoaneurysm formation in the femoropopliteal artery, which can cause restenosis or occlusion of the treated arterial segment. We present a case of a large pseudoaneurysm of the popliteal artery that was observed 18 months after popliteal stenting using a self-expandable nitinol stent. We describe an endovascular approach to overcome this severe complication. Stent fractures are an often overlooked complication of femoropopliteal stenting and can be associated with serious diseases. The popliteal artery was successfully treated using self-expandable Viabahn endoprosthesis.

An Animal Model of Human Peripheral Arterial Bending and Deformation

BACKGROUND

Designing peripheral arterial stents has proved challenging, as implanted devices will repetitively and unpredictably deform and fatigue during movement. Preclinical testing is often inadequate, given the lack of relevant animal models. The purpose of this study was to test the hypothesis that deformation of the human peripheral vasculature could be qualitatively and quantitatively modeled using an experimental animal.

METHODS

Anteroposterior contrast angiography was performed in domestic Landrace-Yorkshire farm pigs. Images were obtained with the hind limbs naturally extended then repeated, (1) flexed approximately 90° at the hip and knee, (2) overflexed in a nonphysiological fashion. Quantitative vascular angiographic analysis was utilized to measure arterial diameter, length, and deformation. Percent axial arterial compression and bending were assessed.

RESULTS

Eight iliofemoral arteries in four animals were imaged. Mean luminal diameters of the iliac and femoral segments in the neutral position were 5.4 ± 0.5 mm and 4.6 ± 0.5 mm. Hind limb physiologic flexion induced profound arterial compression, 17 ± 8% and 29 ± 6% and bending, 36°±10° and 76° ± 13° within the iliac and femoral segments, respectively. With extreme flexion, the femoral artery could be reliably bent >90°. The observed findings exceeded the deformation observed historically within the human superficial femoral (∼5% compression and 10° bending) and popliteal artery (∼10% compression and 70° bending).

CONCLUSIONS

Significant nonradial deformation of the porcine iliofemoral arteries was observed during manual hind limb flexion and exceeded that typically observed in humans. This model constitutes a "worst case" scenario for testing deformation and fatigue of intravascular devices indicated for the human peripheral vasculature.

Balloon Angioplasty Versus Bailout Stenting for Isolated Chronic Total Occlusions in the Popliteal Artery

Aims:

Stenting of the popliteal artery (PA) is generally considered inappropriate due to the high mechanical stress and bending of the artery during knee flexion. Nevertheless, vessel recoil remains problematic following angioplasty procedure for chronic total occlusions (CTOs) and adjunctive stenting may be required. The purpose of this study is to compare balloon angioplasty alone versus bailout stenting for isolated CTO of the PA.

Materials and Methods:

Between March 2012 and October 2016, 43 patients were treated with percutaneous transluminal angioplasty with balloon alone (PTA, n = 16) or bailout stenting percutaneous transluminal angioplasty and stenting (PTAS, n = 27) for de novo CTO of PA. There was no statistically significant difference between both groups with regard to patient demographics and lesions characteristics (calcification severity and lesion length). The median lesion lengths were 67 mm (39.5-78.5) in the PTA group and 94 mm (50-114) in the PTAS group ( p = 0.14). The primary outcome measure was primary patency; secondary outcomes were technical success, primary assisted patency, major amputation, and increased Rutherford classification.

Results:

Technical success rate was 37% and 96.3% in the PTA and PTAS groups, respectively. There was no statistical difference in 12-month primary patency rate (65.8% versus 58.7%; p = 0.15) and primary assisted patency at 12 months (75.2 versus 69.2; p = 0.47) between the 2 groups. Freedom from target lesion revascularization at 12 months was not significantly different, with 85.7% and 81.6% ( p = 0.2) in the PTA and PTAS groups, respectively. One amputation occurred in the PTA group.

Conclusion:

This small cohort suggests that stenting as a bailout procedure in CTO of the PA provides similar results to successful balloon angioplasty. Stenting should only be performed after suboptimal balloon angioplasty with vessel recoil. Due to the large lost to follow-up, strong evidence of a therapy over the other cannot be formulated. Larger studies with longer and stronger follow-up are needed to confirm those results.

Bursting Fracture of Balloon-Expandable Stent and Pseudoaneurysm Formation in the Left Common Iliac Artery and Endovascular Treatment With Graft Stent

Purpose:

To report successful endovascular treatment of a previously implanted balloon-expandable stent bursting fracture with concomitant large pseudoaneurysm formation in the left common iliac artery (LCIA).

Case Report:

A 72-year-old man had been previously treated with balloon-expandable stents for severe stenotic lesion in the LCIA and left external iliac artery. Seven years later, the patient complained pain in both lower legs and back. Angiography demonstrated a 3.5-cm-sized pseudoaneurysm in the LCIA with embedded metal fragments around the lesion. An endovascular treatment was selected using a limb extension graft for endovascular aortic aneurysm repair. The device was successfully deployed, and no endoleak was observed. At 1-month follow-up, computed tomography scan confirmed patency of the implanted stent graft devices in the LCIA and the absence of any endoleak.

Conclusion:

Endovascular approach using a limb extension graft stent for endovascular aortic aneurysm repair can be used for treating stent fracture-related pseudoaneurysm in the common iliac artery.

[Femoropopliteal angioplasty: Short- and mid-term results]

BACKGROUND

Percutaneous endovascular therapy is becoming a primary option for managing femoropopliteal occlusive disease. The purpose of this study was to evaluate the mid-term results of endovascular treatment of femoropopliteal arterial disease.

METHODS

Femoropopliteal percutaneous transluminal angioplasty was performed on 162 consecutive limbs (160 patients) from January 2006 to January 2016.

RESULTS

In our study, 87.6% of patients had critical limb ischemia. Lesions were classified as Trans-Atlantic Inter-Society Consensus (TASC) A (43%), B (43%), C (7%), and D (7%). Femoropopliteal interventions included angioplasty only in 70 cases (43.2%), and the remaining 92 (56.8%) received at least one stent. Technical success was achieved in 98.7% of patients, with three deaths and a major morbidity rate of 15%. The actuarial primary patency at 12 and 36 month was 65.4% and 40.2%, respectively, 33 peripheral reinterventions were performed after femoropopliteal axis occlusion, resulting in an actuarial primary limb preservation rate of 94.4 at 12 months. Comparison between angioplasty only and the use of stent show no difference in primary patency (P=0.832) and limb salvage (P=0.67). Negative predictors of primary patency determined by univariate analysis included popliteal location (P<0.001) and TASC D (P<0.001). However, diabetes mellitus (P=0.001) and poor run off (P<0.001) were the principal predictive factors of limb loss.

CONCLUSION

Femoropopliteal angioplasty can be performed with a low morbidity and mortality. Intermediate primary patency is directly related to TASC classification and popliteal localization.

Crush Deformation of a Balloon-Expandable Stent Implanted in an Infrainguinal Bypass Graft

A 59-year-old man with critical claudication underwent left femoro-anterior bypass grafting, which was uneventful. The graft was tunneled medially across the knee, then anterior to the tibia. His symptoms recurred 1 year later and he was found to have critical stenosis of the vein graft just proximal to the anterior tibial arterial anastomosis. This was treated with scaffolded balloon angioplasty and implantation of a coronary, zotarolimus-eluting balloon-expandable stent, which was also uneventful. However, his claudication again recurred 1 year later. Diagnostic angiography revealed crush, deformation and restenosis of the balloon-expandable stent requiring surgical revision of the bypass graft.

Feasibility and outcomes of interventional treatment for vascular access site complications following transfemoral aortic valve implantation

BACKGROUND

Despite the completion of more than 60,000 transcutaneous aortic valve implantations (TAVI) per year and an approximately 10-15 % incidence of vascular access site complications (VAC), there is a paucity of data on the efficacy and safety of percutaneous VAC treatment.

HYPOTHESIS

Percutaneous endovascular treatment will be an effective treatment of VAC and associated with a low rate of surgical repair. Despite stent placement in proximity to the hip joint, endovascular treatment will be only rarely associated with disabling symptoms or complications.

METHODS

We conducted a retrospective database analysis including 355 patients who underwent TAVI from January 2011 to October 2015. To facilitate the detection of secondary complications of interventional VAC repair, we conducted structured telephone interviews with a focus on new diagnoses or symptoms of peripheral artery disease.

RESULTS

Only four patients (1.1 %) required surgical treatment for VAC. Percutaneous balloon angioplasty (PTA) or stent implantation was required for VAC in 44 patients (12.4 %). The technical success rate of percutaneous VAC treatment was 93 %. Four patients died within 30 days of VAC treatment, but only one fatality was directly attributable to VAC. Post procedure mean hospital stay was numerically prolonged by 2.4 days in the VAC treatment group (P = 0.06). During a median follow-up of 385 days (range 89-909 days) none of the patients were diagnosed with a late VAC or reported a new diagnosis or symptoms of perfusion deficit or peripheral artery disease.

CONCLUSION

Percutaneous treatment of VAC during TAVI is safe and effectively helps to minimize the need for surgery in the vast majority of VAC. During short- and mid-term follow-up, percutaneous VAC management is associated with low complication rates and good clinical outcomes.

A pooled analysis of common femoral and profunda femoris endovascular interventions

Background

Atherosclerotic disease of common femoral and profunda femoris arteries has been historically treated with surgical endarterectomy. Endovascular treatment of common femoral artery and profunda femoris artery disease is increasingly reported in the recent literature. This review summarizes short- and mid-term outcomes of endovascular interventions to the common femoral artery and common femoral artery.

Methods

All published series in the English language were identified through a systematic PubMed search. Standard descriptive statistics, reported as mean ± SD, were applied to perform the pooled analysis and calculate the overall outcome measures. Combined overall effect sizes were calculated using fixed-effect meta-analysis.

Results

The analysis included 20 studies with a total of 836 patients (897 limbs, mean age of 70.5 ± 4.3 years, critical limb ischemia 39.6%). Technical success was 95%. Angioplasty alone was undertaken in 68.8% of cases and stenting in 22.3%. Access complications occurred in 2.4% of cases. Post-operative major adverse limb events occurred in 2% and major adverse cardiovascular events in 1% of cases. Primary patency at 6, 12 and 24 months was 87%, 77% and 73%, respectively. Subgroup analysis revealed a significantly higher mean primary patency at 12 months for routine stenting compared to a selective stenting strategy (91.4% versus 75%; p < 0.05).

Conclusions

Endovascular interventions to the common femoral artery and common femoral artery can be performed safely with high technical success. Endovascular therapy may be a favored approach over endarterectomy for highly selected patients of poor surgical risk, with limited life expectancy and those with wound-healing considerations such as re-operative fields or prone to infection.

Femoropopliteal Artery Stent Fracture with Recurrent In-Stent Reocclusion and Aneurysm Formation: Successful Treatment with Self-Expandable Viabahn Endoprosthesis

Primary stenting in femoropopliteal lesions of intermediate length has recently shown favorable outcomes. However, stent fractures are a concern after bare metal stent implantation. The incidence of stent fracture varies widely (ranging from 2% to 65%) depending on factors such as the treated lesions or stent type and may potentially lead to various complications. We reported a case of stent fracture with complete dislocation combined with recurrent in-stent reocclusion and aneurysm formation in a patient with occlusive disease of the femoropopliteal artery, which was successfully treated with self-expandable endovascular stent graft.

Stent Placement Versus Balloon Angioplasty for the Treatment of Obstructive Lesions of the Popliteal Artery

Background—

Stenting has been shown to improve patency after femoral artery revascularization compared with balloon angioplasty. Limited data are available evaluating endovascular treatment for obstructive lesions of the popliteal artery.

Methods and Results—

This prospective, randomized, multicenter trial compared primary nitinol stent placement to percutaneous transluminal balloon angioplasty in patients with peripheral artery disease Rutherford-Becker class 2 to 5 who had a de novo lesion in the popliteal artery. The primary study end point was 1-year primary patency, defined as freedom from target-lesion restenosis (luminal narrowing of ≥50%) as detected by duplex ultrasound. Secondary end points included target-lesion revascularization rate and changes in Rutherford-Becker class. Provisional stent placement was considered target-lesion revascularization and loss of primary patency. Two hundred forty-six patients were included in this trial. The mean target-lesion length was 42.3 mm. One hundred ninety-seven patients were available for the1-year follow-up. The 1-year primary patency rate was significantly higher in the group with primary nitinol stent placement (67.4%) than in the percutaneous transluminal balloon angioplasty group (44.9%, P =0.002). Target-lesion revascularization rates were 14.7% and 44.1%, respectively ( P =0.0001); however, when provisional nitinol stent placement was not considered target-lesion revascularization and loss in patency, no significant differences prevailed between the study groups (67.4% versus 65.7%, P =0.92 for primary patency). Approximately 73% of patients in the percutaneous transluminal balloon angioplasty group and 77% in the nitinol stent group showed an improvement of ≥1 Rutherford-Becker class ( P =0.31).

Conclusions—

Primary nitinol stent placement for obstructive lesions of the popliteal artery achieves superior acute technical success and higher 1-year primary patency only if provisional stenting is considered target-lesion revascularization. Provisional stenting as part of a percutaneous transluminal balloon angioplasty strategy has equivalent 1-year patency and should be preferred over primary stenting.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT00712309.

Percutaneous management of vascular complications in patients undergoing transcatheter aortic valve implantation

OBJECTIVES

This study sought to investigate the feasibility and safety of percutaneous management of vascular complications after transcatheter aortic valve implantation (TAVI).

BACKGROUND

Vascular complications after TAVI are frequent and outcomes after percutaneous management of these adverse events not well established.

METHODS

Between August 2007 and July 2010, 149 patients underwent transfemoral TAVI using a percutaneous approach. We compared outcomes of patients undergoing percutaneous management of vascular complications with patients free from vascular complications and performed duplex ultrasonography, fluoroscopy, and multislice computed tomography during follow-up.

RESULTS

A total of 27 patients (18%) experienced vascular complications consisting of incomplete arteriotomy closure (n = 19, 70%), dissection (n = 3, 11%), arterial perforation (n = 3, 11%), arterial occlusion (n = 1, 4%), and pseudoaneurysm (n = 1, 4%). Percutaneous stent graft implantation was successful in 21 of 23 (91%) patients, whereas 2 patients were treated by manual compression, 2 patients underwent urgent surgery, and 2 patients required delayed surgery. Rates of major adverse cardiac events at 30 days were similar among patients undergoing percutaneous management of vascular complications and those without vascular complications (9% vs. 8%, p = 1.00). After a median follow-up of 10.9 months, imaging showed no evidence of hemodynamically significant stenosis (mean peak velocity ratio: 1.2 ± 0.4). Stent fractures were observed in 4 stents (22%, type I [6%], type II [16%]) and were clinically silent in all cases.

CONCLUSIONS

Vascular complications after TAVI can be treated percutaneously as a bailout procedure with a high rate of technical success, and clinical outcomes are comparable to patients without vascular complications. Stent patency is high during follow-up, although stent fractures require careful scrutiny.

[S3 guidelines for diagnostics and treatment of peripheral arterial occlusive disease]

This report summarizes the most important aspects of the new German S3 guidelines for the diagnostics and treatment of peripheral arterial occlusive disease (PAOD) from March 2009. The guidelines include definitions and epidemiology of peripheral arterial occlusive disease, diagnostic methods including clinical and technical procedures as well as imaging methods, treatment by non-invasive, interventional and surgical methods and patient care during follow-up. In key messages recommendations are given which are graded corresponding to the scientific evidence concluded from the literature.

Endovascular management of the popliteal artery: comparison of atherectomy and angioplasty

PURPOSE

Symptomatic atherosclerotic disease of the popliteal artery presents challenges for endovascular therapy. We evaluated the technical success, complications, and midterm outcomes of atherectomy and angioplasty involving the popliteal segment.

METHODS

We conducted a retrospective review of outcomes of popliteal artery intervention using atherectomy or angioplasty performed between 2003 and 2008.

RESULTS

A total of 56 patients (36% women, age 72.8 +/- 12.2 years, 77% critical limb ischemia) underwent popliteal atherectomy (n = 18) or angioplasty (n = 38). These patients had similar clinical characteristics, TransAtlantic Intersociety Consensus (TASC)/ TASC II classification, mean lesion length, and runoff scores. We observed a trend toward higher rates of technical success defined as <30% residual stenosis after atherectomy compared to angioplasty (94% vs 71%, P = .08). While angioplasty was associated with a higher frequency of arterial dissection (23% vs 0%, P = .003), atherectomy was associated with a higher rate of thromboembolic events (22% vs 0%, P = 0.01). Adjunctive stenting was used more frequently following angioplasty compared to atherectomy (45% vs 6%, P = .005). Thrombolysis was used to treat embolization in 4 patients in the atherectomy group. The improvement in the ankle-brachial index (ABI) was similar between the 2 treatment groups. Primary patency of the popliteal artery at 3, 6, and 12 months was 94%, 88%, and 75% in the atherectomy group and 89%, 82%, and 73% in the angioplasty group (P = not significant [NS]). There were no significant differences in limb salvage and freedom from reintervention at 1 year between the atherectomy and angioplasty groups.

CONCLUSIONS

Our experience with popliteal artery endovascular therapy indicates a distinct pattern of procedural complications with atherectomy compared to angioplasty but similar midterm patency, limb salvage, and freedom from intervention.

The role of vessel geometry and material properties on the mechanics of stenting in the coronary and peripheral arteries

There have been notably higher rates of restenosis with stents used to restore blood flow to many stenosed peripheral arteries compared with their coronary counterparts. The mechanical environment of arteries such as the femoral and popliteal (and the stent fracture that this can cause) has previously been identified as a contributing factor to the relatively low success rates for this procedure. The aim of this study was to investigate how other factors, namely the differences in geometries and mechanical properties of the arteries and the stents used in them, might influence the outcome in these different arteries. Finite element models of the stents and arteries were created, and the results compared in terms of stresses induced in the arteries, the lumen gain, and the deformation of the stent due to pulsatile loading. It was found that deploying a Nitinol stent in a peripheral artery induced lower stresses in the vessel wall than expanding a stainless steel stent in a coronary artery, although the lumen gain was also lower. The predicted strain amplitude induced in Nitinol stents by the cardiac cycle was below the value required to cause fatigue failure. This study does not provide any evidence to suggest that differences in the geometry and material properties between peripheral and coronary arteries, or the types of stent used to restore vessel patency, are the dominate factors responsible for the higher rates of restenosis observed in peripheral arteries.

Primary nitinol stenting for femoropopliteal disease

The 1- to 2-year primary patency rates associated with self-expanding nitinol stents for the treatment of symptomatic femoropopliteal disease are superior to those for percutaneous transluminal angioplasty (PTA) and the first-generation stainless steel balloon-expandable stents. The advantages of nitinol stents include improved radial strength and flexibility, the ability to recover from being crushed, reduced foreshortening, and (importantly) deployability without balloon dilation of the stent edge (which may decrease the incidence of the edge stenosis, or "candy-wrap" effect, often observed with balloon-expandable stents). The technical success rate associated with primary deployment of nitinol stents is very high, and acute to 6-month patency results are predictably excellent. Prior to the introduction of nitinol stents, the original guidelines (2000) of the multidisciplinary TransAtlantic Inter-Society Consensus (TASC I) recommended only an adjunctive role for femoropopliteal stents following suboptimal PTA. The abbreviated 2007 TASC II report essentially extended this recommendation to nitinol stents. Here, current trials of nitinol stenting in the femoropopliteal segment are discussed, with emphasis on the advantages of primary (and often direct) deployment in selected circumstances dependent on factors including lesion length, lesion location, indication for treatment (critical limb ischemia or claudication, in-stent restenosis, stent-graft restenosis), and the relative appropriateness of other modalities (e.g., covered stents). Technical considerations in primary nitinol stenting are briefly reviewed. Open questions regarding the factors involved in nitinol stent fracture and the possible association of fracture and restenosis are examined in the context of current clinical trials. A new generation of femoropopliteal nitinol stents combining superior durability and flexibility is expected soon. Development and implementation of uniform reporting and surveillance standards is important for optimizing current and future research.

Emergency endovascular management of peripheral artery aneurysms and pseudoaneurysms - a review

Endovascular stenting has been successfully employed in the management of aortic aneurysms; however, its use in managing peripheral arterial conditions remains questionable. We review the utility of endovascular technique in the management of peripheral arterial conditions like aneurysms, pseudoaneurysms and arterio-venous fistulas in the emergency setting. Though long term data about graft patency rates is not yet available, the endovascular approach appears to be a useful minimally invasive technique in situations where open repair is either difficult or not feasible.

Endovascular stenting of large popliteal artery aneurysm is feasible!

INTRODUCTION

Endovascular stenting has been successfully employed in management of aortic aneurysms; however, its utility in managing popliteal aneurysms remains questionable. This is because of the non-availability of long term data about graft patency rates.

CASE PRESENTATION

We report a case of large popliteal artery aneurysm stenting in a patient with significant co-morbidities and high risk for open surgical repair. He underwent successful endovascular stenting of a popliteal artery aneurysm measuring 6.4x9.7 cm extending for approximately 11.0 cm in length with Hemobahn grafts. The graft was patent at 12 months of follow up with complete exclusion of the aneurysm.

CONCLUSIONS

Popliteal stents can be successfully used in treating large popliteal artery aneurysms in patients unfit for open repair.

Fracture of Ni-Ti superelastic alloy under sustained tensile load in physiological saline solution containing hydrogen peroxide

The fracture of Ni-Ti superelastic alloy has been investigated by a sustained tensile-loading test in physiological saline solution containing hydrogen peroxide (0.15M NaCl + 0.3M H(2)O(2)). The fracture always occurs when the applied stress exceeds the critical stress for martensite transformation. In contrast, under a low applied stress, the fracture does not always occur within 1000 h. The fracture is probably mainly caused by localized corrosion associated with the preferential dissolution of nickel ions. In 0.3M H(2)O(2) solution without NaCl, the fracture does not occur even under a high applied stress. The results of the present study imply that one reason for the fracture of the Ni-Ti superelastic alloy in vivo is localized corrosion due to the synergistic effects of hydrogen peroxide and sodium chloride under applied stress.

Stent fracture associated with drug-eluting stents: clinical characteristics and implications

OBJECTIVE

To evaluate the clinical characteristics and implications of stent fracture in drug-eluting stents.

BACKGROUND

Approximately 2.5 million drug-eluting stents are implanted every year worldwide. In 10 randomized controlled trials involving 2,602 patients, no incidence of stent fracture was recognized or reported.

METHODS

From April 2003 to December 2005, 2,728 patients underwent drug-eluting stenting. The angiograms of all 530 patients who underwent repeat angiography were analyzed to identify the presence of stent fracture. We then documented the incidence of adverse events associated with drug-eluting stent fracture and systematically analyzed the clinical, procedural, and structural factors, which might predispose to stent fracture.

RESULTS

Stent fracture was identified in 10 patients. None of these fractures were detectable at the time of stent placement. The median time interval from stent implantation to detection of fracture at repeat angiography was 226 days (range, 7-620 days). Adverse clinical outcomes associated with stent fracture occurred in 7 patients (6 patients had binary restenosis and 1 patient had stent thrombosis), all necessitating repeat intervention. Analysis of potential predisposing clinical, procedural, and structural factors revealed that 4 patients had excessive tortuosity in the proximal segment, and overlapping stents were used in 5 cases. All fractures occurred in sirolimus-eluting stents.

CONCLUSIONS

Stent fracture may represent a new potential mechanism of restenosis and stent thrombosis in drug-eluting stents. Predisposing clinical and procedural factors may be vessel tortuosity and use of overlapping stents. The most important predisposing factor, however, may be stent structure, since all fractures occurred in sirolimus-eluting stents.

Stent fracture and restenosis after placement of a drug-eluting device in the vertebral artery origin and treatment with the stent-in-stent technique

✓ The authors report two cases of stent fracture and restenosis after placement of a drug-eluting device in the vertebral artery (VA) origin, and describe management of restenosis with the stent-in-stent technique. Two women, one 62 and the other 67 years of age, underwent stent placement in the VA origin to treat symptomatic and angiographically significant stenosis in this vessel. Sirolimus-eluting coronary stents (Cypher) were used in both cases. Four months after placement of the devices, the symptoms recurred. Follow-up angiography performed 5 months after insertion of the devices revealed a transverse stent fracture with separation of the fragments and severe in-stent restenosis in both cases. The restenoses were treated with reinsertion of coronary stents (Cypher and Jostent FlexMaster) by using the stent-in-stent technique. After stent reinsertion, the patients exhibited relief of symptoms.

This paper is the first report of fracture in a drug-eluting stent and restenosis after stent placement in the VA origin. Restenosis caused by such a fracture can be managed successfully by performing the stent-in-stent maneuver. The physical properties of metallic devices, stent strut geometry, and anatomical peculiarities of the subclavian artery may be associated with stent fractures. Earlier follow-up angiography studies (within 6 months) are warranted.

Carotid artery dynamics after carotid angioplasty and stenting

Carotid angioplasty and stenting (CAS) has emerged as an alternative treatment for carotid artery occlusive disease. As initial results in patients with an increased surgical risk appeared promising, the popularity of CAS has increased substantially over the last years and CAS has more often been advocated as an alternative to the gold standard, carotid endarterectomy (CEA). Several controlled trials comparing CAS with CEA are currently being conducted. However, long-term results of CAS are still sparse and several issues regarding the inherent differences between treatment modalities have not yet been elucidated. Interestingly, to date, very little attention has been directed towards the mobile features of the carotid artery and the implications of stent placement on carotid artery dynamics.

In vivo MR angiographic quantification of axial and twisting deformations of the superficial femoral artery resulting from maximum hip and knee flexion

PURPOSE

The goal of this study was to quantify in vivo deformations of the superficial femoral artery (SFA) during maximum knee and hip flexion with use of magnetic resonance (MR) angiography to improve description of the complex, dynamic SFA environment.

MATERIALS AND METHODS

Contrast medium-enhanced MR angiography was performed on the leg vasculature of eight healthy adults in the supine and fetal positions. The SFA was defined as the centerline path of the iliofemoral segment from the profunda femoris to the descending genicular artery. Deformations that resulted from flexion from the supine position to the fetal position were quantified with the SFA path and its branches.

RESULTS

Fourteen SFAs shortened from the supine position to fetal position, whereas two lengthened. Six of eight left SFAs twisted counterclockwise, and seven of eight right SFAs twisted clockwise. Straightness percentages for supine and fetal SFAs were 99.1%+/-0.4% and 98.7%+/-0.6%, respectively. From the supine position to the fetal position, the SFA shortened 13%+/-11% (P<.001) and twisted 60 degrees+/-34 degrees (P<.001). SFA arc length and percent shortening were strongly correlated (r>.8) between left and right limbs; however, no significant correlation existed for SFA twist angle.

CONCLUSIONS

Complex and varying vascular and muscular anatomy among study participants made SFA lengths and deformations from the supine position to the fetal position unpredictable a priori; however, there were strong symmetries between left and right SFAs in terms of arc length, length change, and direction of twist. The data show that, from the supine position to the fetal position, the SFA tended to shorten and twist substantially, suggesting these as possible fracture mechanisms and also providing important parameters for stent design.

Effect of exercise on frequency of stent fracture in the superficial femoral artery

Stent fracture has emerged as a new problem in the percutaneous transluminal angioplasty of the superficial femoral artery (SFA). The aim of our study was to delineate the factors influencing nitinol stent fracture in the SFA. Forty consecutive patients with peripheral artery disease who underwent rescue stenting with a nitinol stent (Luminexx, Bard) in the SFA were enrolled between May 2004 and January 2005. Follow-up angiography was performed 13.6+/-1.0 months later to detect stent fracture. Stent fracture occurred in 11 patients (28%). Lesion length>100 mm, the number of stents used, the lesion involving the distal SFA, chronic total occlusion, and walking>5,000 steps per day were more frequently observed in those with stent fracture than in those without fracture. Of these variables, walking>5,000 steps per day was the strongest independent determinant associated with stent fracture by discriminant analysis (p=0.0027). Vigorous exercise adversely affects stent fracture in patients implanted with a nitinol stent in the SFA.