Journal of Endovascular Therapy

To examine the efficacy and integrity of a novel interwoven self-expanding nitinol stent system for the treatment of complex femoropopliteal lesions in a “real world” medical practice.

This retrospective analysis included 107 consecutive patients (77 men; mean age 68.9 years) with atherosclerotic femoropopliteal lesions (occlusions in 31%) who underwent implantation of 137 SUPERA stents. The patients were followed for up to 24 months by Doppler ultrasound examinations, radiography of the stent, and assessments of Rutherford-Becker class and ankle-brachial index (ABI).

The mean implanted stent length was 111±50 mm (range 40–270). Procedure success (residual stenosis <30%) was achieved in 99% of procedures. The 6-, 12-, and 24-month cumulative primary patency rates (± standard error) were 93.1%±2.5%, 84.7%±3.6%, and 76.1%±4.5%, respectively, and the secondary patency rates were 99.0%±0.1%, 94.8%±0.2% and 91.9%±0.3%, respectively. Between baseline and 24 months, mean ABI increased from 0.68±0.14 to 0.87±0.10 and the mean Rutherford-Becker class decreased from 3.3±0.7 to 2.0±1.0 (p=0.0001 for both). Radiographs performed in 91 patients at a mean of 16.8±7.0 months found no stent fractures.

Over a 2-year surveillance period, excellent durability without stent fractures was documented after implantation of the SUPERA stent in complex femoropopliteal lesions. In addition, significant improvements were observed in symptom classification and hemodynamics.

To investigate the long-term outcomes of nitinol stenting in femoropopliteal lesions and to determine the factors associated with restenosis.

Between December 2003 and December 2009, 861 patients (603 men; mean age 72 years) underwent nitinol stenting of the femoropopliteal segment in 1017 limbs. A quarter (26%) of the patients had critical limb ischemia. Mean lesion length was 152±93 mm. Stent patency was assessed by either duplex ultrasound or angiography and analyzed by Kaplan-Meier estimation. The determinants of restenosis were explored with Cox proportional hazard regression analyses; the results are presented as the hazard ratio (HR) and 95% confidence interval (CI). Risk stratification of primary patency was subsequently analyzed using a score based on the significant prognostic factors identified in the multivariate model.

Stent fracture occurred in 10% (104 limbs) of the lesions. At 1, 3, and 6 years, the primary patency rates were 77%, 67%, and 63%; secondary patency rates were 91%, 87%, and 87%; freedom from femoropopliteal bypass grafting was 99%, 97%, and 96%, respectively. Multivariate Cox regression analysis identified female gender (HR 1.899; 95% CI 1.318 to 2.737, p<0.001), ankle-brachial index <0.6 (HR 1.921; 95% CI 1.348 to 2.736, p<0.001), TASC II C/D lesion (HR 2.068; 95% CI 1.346 to 3.177, p=0.0009), stent fracture (HR 1.937; 95% CI 1.203 to 3.118, p=0.006), and the absence of cilostazol administration (HR 2.102; 95% CI 1.394 to 3.172, p<0.001) as strong independent factors associated with restenosis. After assigning a risk score based on the outcomes of the multivariate regression analysis (1 each for female gender, ABI <0.6, TASC II C/D, stent fracture, and absence of cilostazol therapy), primary patency was found to be lower in limb groups with a higher cumulative score (12-month primary patency: score 0: 93%, score 1: 80%, score 2: 73%, score 3; 47%, score 4: 0%, respectively; p<0.001).

Endovascular therapy using nitinol stents for FP lesions yielded acceptable outcomes up to 6 years. Risk stratification for patency can play an important role in estimating future occurrence of restenosis after nitinol stent implantation in FP lesions.

To report the midterm follow-up after treatment of various aortoiliac pathologies in an acute setting using reversed Zenith iliac limb extensions when appropriately sized stent-grafts were not available.

From 2005 to 2007, 12 patients (10 men; mean age 71.5 ± 7.3 years) were treated with reversed Zenith iliac limb extensions for solitary iliac artery aneurysms (n=8), an abdominal aortic aneurysm (AAA) in a small caliber aorta (n=1), an anastomotic pseudoaneurysm in an aortobi-iliac graft (n=1), a hypogastric artery aneurysm (n=1), and a ruptured AAA secondary to a late type Ib endoleak after Talent stent-graft implantation (n=1). The Zenith iliac limb extensions were deployed on the back table and reloaded in a reversed manner to treat aneurysms and other lesions with a broad range of different diameter necks and landing zones.

The technical success rate was 100%, and no endoleaks were present at the end of the procedures. The endoleak patient with the ruptured AAA died owing to respiratory insufficiency. The other 11 patients have a mean follow-up of 29±9 months. In this period, 2 patients received a femorofemoral crossover bypass because of an occluded iliac limb extension. One patient had a type II endoleak without growth of the iliac aneurysm. Two patients died of a ruptured 4.4-cm AAA at 16 months and of respiratory insufficiency due to metastases at 47 months, respectively.

When necessary, it is feasible to use a revered Zenith limb extension to treat solitary iliac aneurysms and other aortoiliac pathologies, achieving satisfactory midterm outcomes.

To investigate a single-acquisition computed tomographic angiography (CTA) protocol using a prebolus injection technique to visualize the stent-graft lumen and endoleak after endovascular aneurysm repair (EVAR).

Of 162 EVAR patients referred for CTA over a 2-year period, 18 (15 men; mean age 66.4 years) with an endoleak met the study inclusion criteria, which included constant endoleak size and scans using 3 different CT protocols at least once during follow-up: monophasic CTA (C1), biphasic CTA (C2.1 and C2.2), and single-acquisition CTA using a prebolus (PB). All CTA examinations were performed with the same overall volume of contrast medium (120 mL) and were started manually using a bolus-tracking technique. Attenuation was measured within the aortic lumen proximal to the stent prosthesis (Ao) and within the endoleak itself (EL).

Mean attenuation ranged between 200 (C2.2) and 313 HU (C2.1) within Ao and between 172 (C2.2) and 235 HU (C2.1) within the endoleak. The attenuation differences between Ao (C1) and Ao (PB), as well as between Ao (C2.1) and Ao (PB), were not statistically significant, while the attenuations of Ao (C2.2) and Ao (PB) differed significantly (p<0.001), with higher attenuation in PB. Compared to EL (PB), none of the mean EL attenuation values (C1, C2.1, and C2.2) differed significantly.

This prebolus CTA protocol combines late-phase attenuation of a biphasic image acquisition protocol for endoleak visualization with high opacification of the stent lumen without exposing the patient to radiation twice.

To evaluate the midterm outcomes and potential risk factors associated with the fascia suture technique (FST) for closure of femoral artery access sites after percutaneous endovascular aneurysm repair (EVAR).

Between April 2007 and April 2008, 100 consecutive EVAR cases were evaluated retrospectively. A third of the procedures were emergent (16 ruptured aneurysms). Of the 187 femoral access sites, 160 (85.5%) were closed by the FST as a first choice. Pre- and postoperative chart and imaging data were collected from computerized medical records for analysis of demographics and the rate of complications (bleeding, infection, thrombosis, pseudoaneurysms, and stenosis). Preoperative risk factors for FST failure were analyzed with regard to obesity (based on the subcutaneous fat layer), plaque at the femoral access site, and stenosis based on the pre- and 1-year postoperative computed tomography scans.

Of the 160 FST closures, 146 (91.3%) were technically successful. The 14 (8.8%) technical failures were converted to open cutdown intraoperatively because of bleeding (11, 6.8%), inadequate limb perfusion (2, 1.2%), and a broken guidewire (1, 0.6%). Two (1.2%) pseudoaneurysms required surgical repair after 2 weeks. Data from the 1-year follow-up showed no signs of increased stenosis, thrombosis, or formation of plaque. Nine small (<1 cm³) pseudoaneurysms were detected and managed conservatively. No preoperative risk factors were associated with FST failure.

The fascia suture technique seems to be safe, effective, and simple to use for closing percutaneous access sites after EVAR. Complications are rare, and the outcome is not affected by obesity, femoral calcification, or femoral artery stenosis.

To measure the stiffness of commonly used “stiff” guidewires in terms of their flexural modulus, an engineering parameter related to bending stiffness.

Eleven different intact stiff guidewires were selected to undergo a 3-point bending test performed using a tensile testing machine. Testing was performed on 3 new and intact specimens of each guidewire at 10 locations along the wire's length, excluding the floppy tip. The flexural modulus (in gigapascals, GPa) was calculated from the results of the bending test.

The flexural modulus of the plain Amplatz wire was 9.5 GPa compared to 11.4 to 14.5 GPa for the “heavy duty” wires. Within the Amplatz family of guidewires, the flexural modulus was 17 GPa for the “stiff,” 29.2 GPa for the “extra stiff,” 60.3 GPa for the “super stiff,” and 65.4 GPa for the “ultra stiff.” The Backup Meier measured 139.6 GPa and the Lunderquist Extra Stiff 158.4 GPa.

The Instructions for Use of some endovascular devices specify a wire type selected from a range of undefined “stiffness” descriptors. These descriptors have little correlation with the measured flexural modulus. Two guidewires with the description “extra stiff” can have a 5-fold difference in flexural modulus. We recommend that guidewire catalogues and packaging include the flexural modulus and that device manufacturers amend their Instructions for Use accordingly.

To evaluate the feasibility of using covered stents vs. bare stents in a model of central vein stenosis with an arteriovenous graft created to mimic the conditions in hemodialysis patients.

In 7 mongrel dogs, an expanded polytetrafluoroethylene-covered nitinol stent was placed in one common iliac vein and a bare stent was placed in the contralateral vein. Arteriovenous grafts were created bilaterally between the common femoral artery and vein to induce endothelial damage. Neointima formation in the covered stents was compared to the bare stents at 12 weeks using microscopy and histochemical staining.

Two dogs were excluded due to thrombosis and infection of the arteriovenous grafts, but all stents in the remaining 5 dogs were patent. Smooth, complete neointimal coverage was observed on the inner surface of all the covered stents without intraluminal thrombus. In contrast, incomplete neointimal coverage was seen in all bare stents, with small focal thrombi adhering to the neointima on 3 bare stents. Focal nodular neointimal hyperplasia with denudation of the endothelium was observed in only 2 bare stents. Mean neointimal thickening was significantly greater in the covered stents. Eccentric neointimal thickening was observed at the inflow and outflow segments of both types of stents.

Covered stents are technically feasible for the treatment of central vein stenosis, and they demonstrate complete, smooth neointimal coverage in normal central veins, but they also display greater neointimal thickening than bare stents.

To evaluate our experience with treatment of giant arteriovenous fistulae (AVFs) involving the renal and visceral vasculature and assess outcomes.

Clinical data from 12 consecutive patients (10 women; median age 58 years, range 37–79) undergoing intervention for 14 giant renal/visceral AVFs over a 15-year period (1994–2008) were retrospectively reviewed. Only patients with extra-parenchymal, wide arteriovenous communications were included. Thirteen were located in the renal artery and one in the splenic artery. The etiology was most likely post-traumatic/iatrogenic in 6 patients, idiopathic in 4 (1 bilateral), congenital in 1 (bilateral), and one was associated with fibromuscular dysplasia. In 4 cases, the lesion was asymptomatic.

Two large renal AVFs were treated with open surgery: one elective AV fistula repair early in our experience and the other an emergent nephrectomy for rupture. Twelve AV fistulae were closed successfully using endovascular techniques performed solely through the feeding vessel without cannulating the draining vein. All symptomatic patients, except one with continued dyspnea from cardiac causes, had complete symptomatic relief. There was no mortality. Morbidity included 2 access site hematomas that were managed conservatively. Loss of renal parenchyma ranged from 5% to 30%, but median serum creatinine levels remained stable.

Endovascular treatment of giant renal/visceral AVFs is challenging but feasible and safe, with good organ preservation. Endovascular techniques have replaced open surgical repair as a first-line treatment for these challenging lesions.