Effect of Stent Strut Interval on Neointima Formation After Venous Stenting in an Ovine Model.

OBJECTIVE: The impact of stent design on venous patency is not well studied. The purpose of this study was to investigate the effect of stent material burden on endothelial coverage of stented venous segments, which may contribute to vessel healing and patency. METHODS: Segmented self expanding bare nitinol stents (18 × 50 mm) comprising 5 mm long attached metallic rings separated by 2, 5, or 8 mm gaps were implanted in the inferior vena cava (IVC) of 10 sheep. These stents were designed and manufactured for the purposes of this study. At six, 12, and 24 weeks after implantation the animals were euthanised and the stented vessels harvested for histomorphometric analysis. Three sections from the metallic part as well as the gaps between the struts were reviewed for quantification of endothelialisation after six, 12, and 24 weeks. The intimal thickness over and between the stent struts was measured. The endothelialisation score (graded from 1 for complete luminal endothelialisation to 5 for absence of endothelial cells) was determined. RESULTS: All stents were successfully deployed and all 10 sheep survived until the time of harvesting. Macroscopic inspection after 24 weeks showed only partial endothelialisation over stents with 2 mm and 5 mm skipped segments, whereas the stents with 8 mm skipped segments were totally incorporated into the vein wall. After 24 weeks, the mean (SD) neointimal thicknesses over stent struts with 2 mm, 5 mm, and 8 mm skipped segments were 254.0 (51.6), 182.2 (98.1), and 194.6 (101.1) µm, respectively. Comparison of endothelialisation scores of stents over time showed statistically significantly better endothelialisation over stents with 8 mm gaps after 12 and 24 weeks. CONCLUSION: Stent designs providing structural support to veins with larger gaps between the scaffold material appear to lead to faster and more complete endothelialisation as well as a thinner intimal layer.

Iliocaval Skip Stent Reconstruction Technique for Chronic Bilateral Iliocaval Venous Occlusion.

PURPOSE: To report safety and efficacy of a skip stent technique using nitinol stents in patients with chronic bilateral iliocaval venous occlusions. MATERIALS AND METHODS: A retrospective analysis of 48 consecutive patients (32 men; mean age, 40.7 years; age range, 18-68 years) with chronic bilateral iliocaval obstructions treated using a nonoverlapping stent technique was conducted at a single center. None of the patients had May-Thurner syndrome. Iliocaval confluence was treated by deploying a nitinol stent in inferior vena cava (IVC) and a nitinol stent in each common iliac vein close to the caval stent. Patency of stents was assessed by duplex US at 2 weeks, 3 months, and 6 months and yearly thereafter. RESULTS: Recanalization and stent reconstruction was technically successful in 47 (98%) patients. The sinus-XL venous stent was used to treat IVC (95 [100%]). Common iliac and external iliac veins were treated with sinus-Venous and VENOVO stents (80 [83%] and 16 [17%] limbs, respectively). External iliac and common femoral veins were treated with sinus-Venous and VENOVO stents (83 [92%] and 7 [18%] limbs, respectively). Early thrombosis (< 30 days) of the iliac vein with stent occurred in 2 limbs. Cumulative primary, assisted primary, and secondary patency rates at 30 months were 74%, 83%, and 97%. CONCLUSIONS: Findings of this study suggest that leaving a skipped lesion at the level of iliocaval confluence may not adversely affect stent patency. Patency rates were comparable with other reported techniques of stent reconstruction at the level of iliocaval confluence.

Total IN.PACT drug-coated balloon initiative reporting pooled imaging and propensity-matched cohorts.

OBJECTIVE: Randomized controlled trials have shown that drug-coated balloons (DCBs) provide superior results compared with percutaneous transluminal angioplasty (PTA) for the treatment of femoropopliteal artery disease. However, these trials have generally included short lesions, few occlusions, and small sample sizes. The present study was an individual-level pooled analysis of duplex ultrasonography (DUS) core laboratory-adjudicated and clinical events committee-adjudicated IN.PACT Admiral DCB subjects across two randomized controlled trials and two single-arm prospective studies to characterize the safety and effectiveness of DCB compared with PTA. METHODS: The subjects were treated with DCB (n = 926) or PTA (n = 143). The end points through 12 months included DUS core laboratory-adjudicated primary patency and clinically driven target lesion revascularization (CD-TLR) using Kaplan-Meier estimates and primary safety using proportions. A propensity-matched analysis of DCB (n = 466) to PTA (n = 136) was conducted to address confounders. RESULTS: At 12 months, DCB compared with PTA had significantly greater primary patency (88.8% vs 53.9%; P < .001), freedom from CD-TLR (94.3% vs 80.2%; P < .001), and better primary safety composite end point (94.1% vs 78.0%; P < .001). After propensity-matched analysis, DCB remained superior to PTA at 12 months for primary patency (90.5% vs 53.8%; P < .001), freedom from CD-TLR (96.9% vs 80.7%; P < .001), and the primary safety composite end point (96.3% vs 78.4%; P < .001). Across multiple prespecified subgroup analyses, including provisional stenting, DCB remained persistently superior to PTA. CONCLUSIONS: In the largest, DUS core laboratory-adjudicated, multiethnic, pooled DCB series to date, the IN.PACT Admiral DCB demonstrated significantly greater primary patency, freedom from CD-TLR, and better composite safety at 12 months compared with PTA.

Embolization of bronchial arteries with N-butyl cyanoacrylate for management of massive hemoptysis: a technical review.

N-butyl cyanoacrylate (NBCA) is an adhesive material, which has been used as an embolic agent in various vascular beds. Its role in the management of patients with acute massive hemoptysis has not been reported. In this article we report our experience with 12 such patients who underwent bronchial artery embolization using NBCA and compare the results with 36 procedures using polyvinyl alcohol (PVA) particles. As compared with PVA, NBCA embolizations appear more durable, leading to fewer rebleeds. There were 12 episodes of recurrent hemoptysis after 36 procedures using PVA (33%) with 8 being due to bleeding from a previously embolized vessel. Conversely, there were only 2 of the 12 patients who were treated by NBCA who experienced rebleed (16.6%). In this article, we describe the technical nuances of NBCA embolization of bronchial arteries and review potential pitfalls.

Persistent and recurrent postsurgical varicoceles: venographic anatomy and treatment with N-butyl cyanoacrylate embolization.

PURPOSE: To elucidate the mechanism of persistence or recurrence of varicoceles after surgical repair by examining the venographic anatomy, and to review the efficacy of treatment of these patients with n-butyl cyanoacrylate (NBCA) embolization. MATERIALS AND METHODS: From 2001 to 2007, 17 patients with persistent or recurrent varicoceles were studied by retrograde venography 4 months to 18 years after open surgical repair. All patients were then treated with NBCA glue embolization of the entire gonadal vein and the venographically identified duplications and collateral vessels, with three patients undergoing bilateral procedures. Venographic anatomy and clinical success were retrospectively analyzed. RESULTS: The majority of patients (65%) exhibited duplications draining into a single left gonadal vein. Duplications were most frequently found to be confined to the pelvis and inguinal canal. Communication with other retroperitoneal veins, including the renal hilar, lumbar, iliac, and circumaortic renal vein, was relatively uncommon. NBCA embolization effectively treated the main gonadal vein as well as the duplications and communications, with only one patient developing thrombophlebitic complications. CONCLUSIONS: Duplication of the gonadal vein in the pelvic or inguinal region with apparent incomplete ligation or resection is a common finding in patients with persistence or recurrence of varicocele after surgery. NBCA embolization effectively treats these duplicated vessels, resulting in a high rate of clinical success on short-term follow-up.

Comparison of a new polytetrafluoroethylene-covered metallic stent to a noncovered stent in canine ureters.

The aim of this study was to determine the feasibility of using a newly designed polytetrafluoroethylene (PTFE)-covered metallic stent in the ureter by comparing its effectiveness with that of the noncovered stent in a canine model. We placed 14 stents in the ureters of seven mongrel dogs that weighed 30-40 kg each. The covered and noncovered stents were deployed in the right and left ureters, respectively, of six dogs. In the seventh dog, a covered stent and a double-J catheter were inserted in the right ureter, and a covered stent only was inserted in the left ureter. The first six dogs were sacrificed at 5, 10, and 15 weeks after deployment of the stents (two for each follow-up period), and the seventh dog was sacrificed at 30 weeks. There was no migration or poor expansion of any of the stents observed on plain radiography. On intravenous pyelogram and retrograde pyelogram, all of the covered stents at each follow-up period had patent lumens at the stented segments without hydronephrosis, and the passage of contrast material through it was well preserved. The noncovered stents in the dogs sacrificed at 5 and 10 weeks and one of the two dogs sacrificed at 15 weeks showed near-complete occlusion of the stent lumen due to ingrowth of the soft tissue, and severe hydronephrosis was also noted. The noncovered stent in the other dog sacrificed at 15 weeks showed the passage of contrast material without hydronephrosis, but the lumen of the stent was still nearly occluded by the soft tissue. There was no evidence of hydronephrosis or passage disturbance of the contrast material in both ureters of the dog sacrificed at 30 weeks. We conclude that the newly designed PTFE-covered stent effectively prevented the luminal occlusion caused by urothelial hyperplasia compared to the near-total occlusion of the noncovered stents, and no migration of the covered stents was noted.

Stent-graft treatment of extracranial carotid and vertebral arterial lesions.

Five patients with pseudoaneurysms of the carotid artery (n = 4) and an arteriovenous fistula of the vertebral artery (n = 1) were treated with stent-grafts. Commercially made devices were used in all but one of the patients. In four of the five patients, the pathology was successfully excluded. One patient had a small type-I endoleak. There were no immediate procedure-related complications or neurologic sequalae. All experienced immediate resolution of symptoms. One patient was lost to follow-up after discharge and another died 2 weeks after intervention. The remaining patients remained asymptomatic with patent stent-grafts after follow-up periods of 14, 16, and 46 months, respectively.

Novel intravascular ultrasound-guided method to create transintimal arterial communications: initial experience in peripheral occlusive disease and aortic dissection.

PURPOSE: To report our experience using a commercially available catheter-based system equipped with an intravascular ultrasound (IVUS) transducer to achieve controlled true lumen re-entry in patients undergoing subintimal angioplasty for chronic total occlusions (CTO) or aortic dissections. METHODS: During an 8-month period, 10 patients (6 men; mean age 73.4 years) with lower extremity (LE) ischemia from CTOs (n=7) or true lumen collapse from aortic dissections (n=3) were treated. Subintimal access and controlled re-entry of the CTOs were performed with a commercially available 6.2-F dual-lumen catheter, which contained an integrated 64-element phased-array IVUS transducer and a deployable 24-G needle through which a guidewire was passed once the target lumen was reached. The occluded segments were balloon dilated; self-expanding nitinol stents were deployed. In the aortic dissections, fenestrations were performed using the same device, with the IVUS unit acting as the guide. The fenestrations were balloon dilated and stented to support the true lumen. RESULTS: Time to effective re-entry ranged from 6 to 10 minutes (mean 7) in the CTOs; antegrade flow was restored in all 7 CTOs, and the patients were free of ischemic symptoms at up to 8-month follow-up. In the aortic dissection cases, the fenestrations equalized pressures between the lumens and restored flow into the compromised vessels. There were no complications related to the use of this device in any of the 10 patients. CONCLUSIONS: Our preliminary results demonstrate the feasibility of using this catheter-based system for subintimal recanalization with controlled re-entry in CTOs and for aortic flap fenestrations in aortic dissections. This approach can improve the technical success rate, reduce the time of the procedure, and minimize potential complications.

The "Y" stent: a technique using nitinol stents to treat bifurcations.

PURPOSE: To investigate a new method of stent deployment using commercially available self-expanding stents to treat bifurcation lesions, providing complete lesion coverage without obstructing branches. METHODS: After preliminary in vitro and clinical testing with biliary obstructions, 11 vascular obstructive lesions in 10 patients (7 men; mean age 63 years, range 32-81) were treated by percutaneous Y-shaped stenting. Five patients had iliac arterial stenoses involving the iliac bifurcation; the other 5 patients had 6 central venous obstructions involving branch points. Bifurcated stents were constructed in situ by deploying a nitinol stent extending into one branch and selective balloon fracturing of struts to create a fenestration. A second stent was deployed through the hole, followed by symmetrical fracturing of struts in the second stent to form a Y-shaped configuration. RESULTS: All deployments were technically successful and resulted in complete coverage of the bifurcation lesions. Protrusion of fractured stent material into flow lumens was minor as determined by angiography, intravascular ultrasound, and passage of balloons, but it required the stents to be oversized. The lengths and luminal diameters were tailored for each arm of the Y-shaped stents. CONCLUSIONS: In situ creation of a Y-shaped stent using 2 self-expanding nitinol stents is a feasible option with potential advantages in the treatment of obstructive lesions involving a bifurcation.