Fracture of popliteal artery stents

A case of popliteal stent fracture with pseudoaneurysm formation

We describe a case of angiographically documented stent fracture and pseudoaneurysm formation in a patient with femoropopliteal disease, which was successfully treated with deployment of an endovascular stent graft. Technical aspects of the procedure are discussed and the experience with stent fractures previously reported in the literature is reviewed.

The Arterial Folding Point During Flexion of the Hip Joint

PURPOSE

Endovascular stents placed in periarticular vessels may be at a greater risk of neointimal hyperplasia and eventual occlusion than those placed in non-periarticular vessels. The purpose of this study was to investigate the location of maximal conformational change along the iliac and femoral artery, the folding point, during flexion of the hip joint and its location relative to the hip joint and the inguinal ligament.

METHODS

Seventy patients undergoing femoral artery catheterization were evaluated. The patients were 47 men and 23 women and ranged in age from 26 to 75 years (mean 54 years). The arteries (right:left=34:36) were measured using a marked catheter for sizing vessels. Fluoroscopic images were obtained in anteroposterior and lateral projections in neutral position, and in the lateral projection in flexed position of the hip joint. The folding point was determined by comparing the lateral projection images in the neutral and flexed positions. The distance from the acetabular roof to the folding point and the distance from the inguinal ligament to the folding point was evaluated.

RESULTS

The folding point was located 42.8 +/- 28.6 mm cranial to the acetabular roof and 35.1 +/- 30.1 mm cranial to the inguinal ligament. As the patient's age increased, the folding point was located more cranially (p < 0.001).

CONCLUSIONS

The folding point during flexion of the hip joint was located 42.8 +/- 28.6 mm cranial to the acetabular roof and 35.1 +/- 30.1 mm cranial to the inguinal ligament. As the patient's age increased, the folding point was located more cranially. When a stent is inserted over this region, more attention may be needed during follow-up to monitor possible occlusion and stent failure.

Impact of head movements on morphology and flow in the internal carotid artery after carotid angioplasty and stenting versus endarterectomy

OBJECTIVE

Because stents can cause vessel angulation during movement, we hypothesized that internal carotid artery (ICA) stents might lead to alterations of cerebropetal blood flow. This study assessed three-dimensional anatomy and volumetric flow rate (VFR) in the ICA in various head positions by comparing patients treated with carotid angioplasty and stenting (CAS) with patients treated with carotid endarterectomy (CEA).

METHODS

Three-dimensional time-of-flight magnetic resonance angiography and magnetic resonance flow quantification were performed on six subjects after CAS (median age, 70 years) and on six subjects after CEA (median age, 67 years). All investigations were performed in five head positions: neutral, bent forward, bent backward, and turned to the treated, ipsilateral side and to the contralateral side. Maximum-intensity projection reconstructions were obtained to measure maximal angulation of the ICA in the forward, backward, ipsilateral, and contralateral positions compared with neutral. Subsequently, the plane perpendicular to the ICA, 1 cm distal to the stent or 4 cm distal to the carotid bifurcation (CEA patients), was established. The VFR through this plane was measured for each position, and the forward, backward, ipsilateral, and contralateral positions were compared with neutral.

RESULTS

In CAS patients, there was a median change in ICA angulation of +10.2 degrees (interquartile range, +7.3 degrees to +17.9 degrees ) in the forward position, compared with +0.2 degrees (-1.0 degrees to +2.4 degrees ) in CEA patients ( P = .016). In all other head positions, there was no statistically significant difference in angulation change. There was no statistically significant difference in VFR change between groups in any of the head positions tested.

CONCLUSIONS

There was a significant increase in ICA angulation in CAS patients if the head was bent forward; this was not observed in CEA patients. This angulation change did not lead to significant acute changes in cerebropetal blood flow, but it might have chronic effects not yet tested.

Prevalence and clinical impact of stent fractures after femoropopliteal stenting

OBJECTIVES

The aim of this study was to investigate the occurrence and the clinical impact of stent fractures after femoropopliteal stenting.

BACKGROUND

The development of femoral stent fractures has recently been described; however, there are no data about the frequency and the clinical relevance.

METHODS

A systematic X-ray screening for stent fractures was performed in 93 patients. In total, 121 legs treated by implantation of self-expanding nitinol stents were investigated after a mean follow-up time of 10.7 months. The mean length of the stented segment was 15.7 cm.

RESULTS

Overall, stent fractures were detected in 45 of 121 treated legs (37.2%). In a stent-based analysis, 64 of 261 stents (24.5%) showed fractures, which were classified as minor (single strut fracture) in 31 cases (48.4%), moderate (fracture of >1 strut) in 17 cases (26.6%), and severe (complete separation of stent segments) in 16 cases (25.0%). Fracture rates were 13.2% for stented length < or =8 cm, 42.4% for stented length >8 to 16 cm, and 52.0% for stented length >16 cm. In 21 cases (32.8%) there was a restenosis of >50% diameter reduction at the site of stent fracture. In 22 cases (34.4%) with stent fracture there was a total stent reocclusion. According to Kaplan-Meier estimates, the primary patency rate at 12 months was significantly lower for patients with stent fractures (41.1% vs. 84.3%, p < 0.0001).

CONCLUSIONS

There is a considerable risk of stent fractures after long segment femoral artery stenting, which is associated with a higher in-stent restenosis and reocclusion rate.

Biomechanical Incompatibility of Popliteal Stent Placement

Peripheral stents or endografts in specific arterial segments are exposed to extreme mechanical stress. Despite high rates of primary technical success, mechanical bending due to knee joint flexion can limit long-term patency of stents or endografts in the popliteal artery or the femoropopliteal segment. Every stent or endograft responds differently to bending during knee joint flexion, which can be revealed only by functional investigation. Mechanical bending has to be considered in future studies to assess the influence of differences in stent design, material, or postinterventional drug treatment on the long-term patency of endoprostheses in the femoropopliteal segment. To demonstrate the concept of biomechanical incompatibility, we present several illustrations of different stent designs placed in the popliteal artery.

Advances in stent technology and drug-eluting stents

From an initially simple concept, vascular stents have evolved into highly specialized instruments, and are poised to develop into sophisticated drug-delivery systems. Although primary research has mostly targeted the coronary circulation, newer generation stents, deliverable almost anywhere, retarding neointimal hyperplasia and thrombosis, and promoting endothelial overgrowth, will offer the next approximation of true vascular healing. This, in turn,promises to promote less invasive, safer, and finally durable endovascular solutions to current surgical problems.

Stent-Assisted Angioplasty at the Level of the Common Femoral Artery Bifurcation:Midterm Outcomes

PURPOSE

To report the midterm outcome after stent-assisted angioplasty of occlusive disease at the common femoral artery bifurcation.

METHODS

Between 1995 and 2002, 27 consecutive patients (18 men; mean age 70 years, range 47-90) underwent angioplasty with stent implantation in 33 limbs; target sites included 19 common femoral arteries, the origins of 2 superficial or 4 profunda femoris arteries, and 8 bypass anastomoses.

RESULTS

Technical success was 100%. Patients were followed for a mean 30 months (95% CI 21 to 39), at which time the cumulative primary patency was 86% (95% CI 85% to 88%). At 3 years, 83% of the arteries were patent. Five restenoses were due to neointimal hyperplasia in 4 cases (3 bypass grafts) and strut failure of the only balloon-expandable stent used in this series. Restenoses due to neointimal hyperplasia at bypass anastomoses (3/ 8) were more common than in native arteries (2/25) (p=0.078); cumulative primary patency for the bypass subgroup was 71% (95% CI 59% to 82%) at a mean 23-month follow-up; 75% and 60% of the anastomoses were patent after 1 and 2 years, respectively.

CONCLUSIONS

Angioplasty of obstructions in the common femoral artery and its bifurcation with implantation of self-expanding stents shows good midterm primary patency. Native artery lesions have a better outcome than stenoses at bypass anastomoses. The procedure does not preclude further endovascular interventions at the puncture site.