Guidelines for Stenting in Infrainguinal Arterial Disease

Smooth muscle cell-targeted RNA ligand promotes accelerated reendothelialization in a swine peripheral injury model

The local delivery of antiproliferative agents to inhibit neointimal growth is not specific to vascular smooth muscle cells (VSMC) and delays reendothelialization and vascular healing. This investigation was intended to evaluate the effect of luminal delivery of a VSMC-specific aptamer on endothelial healing. The impact of an RNA aptamer (Apt 14) was first examined on the migration and proliferation of primary cultured porcine aortic endothelial cells (ECs) in response to in vitro scratch wound injury. We further evaluated the impact of Apt 14 on reendothelialization when delivered locally in a swine iliofemoral injury model. Although Apt 14 did not affect EC migration and proliferation, in vitro results confirmed that paclitaxel significantly inhibited EC migration and proliferation. En face scanning electron microscopy demonstrated confluent endothelium with elongated EC morphology in Apt 14-treated arteries 14 and 28 days post-treatment. In contrast, vessels treated with paclitaxel-coated balloons displayed a cobblestone morphology and significant platelet and fibrin attachment at cell junctions. These results provide the first evidence of the efficacy of a cell-targeted RNA aptamer to facilitate endothelial healing in a clinically relevant large animal model.

Safety of short 3-hour recovery and same-day discharge following lower-limb angioplasty in outpatients with intermittent claudication and critical limb ischaemia

AIM

To investigate the safety and efficacy of short recovery day-case pathway following lower-limb angioplasty in both intermittent claudication and critical limb ischaemia patients.

MATERIALS AND METHODS

A retrospective analysis was undertaken of the medical records of consecutive outpatients treated with lower-limb angioplasty over a 1-year period within an interventional radiology (IR) day-case unit in a high-volume vascular centre. Standard post-angioplasty care at York Teaching Hospital is discharge 3 h after puncture site haemostasis without the routine use of closure devices. The rates of successful same-day discharge, procedure success, complications, and re-admissions were calculated with 30-day follow-up.

RESULTS

The cohort included 301 patients (57% intermittent claudication and 43% critical limb ischaemia) undergoing 605 angioplasties using access sheath size ranging from 4 to 7 F. Closure devices were used in only 7% of patients. Successful same-day discharge achieved in 98% of patients (294/301), with seven admitted overnight because of complications. Eleven patients (3.6%) were re-admitted within 30 days. Technical success rates were 92%, and 96% when including partially successful interventions, with 4% technical failure. Twelve patients (4%) developed minor complications and four major complications (1%). There were no significant differences in complication rates between small and larger sheath sizes (p>0.05). No procedure-related death was recorded within 30 days.

CONCLUSION

Lower-limb angioplasty can be performed safely as day-case procedure with a short recovery protocol within IR departments for both patients with intermittent claudication (IC) and critical limb ischaemia (CLI). This may significantly increase patient throughput and alleviate pressure on stretched hospital inpatient resources by safely discharging patients on the day of procedure.

Local intraluminal delivery of a smooth muscle-targeted RNA ligand inhibits neointima growth in a porcine model of peripheral vascular disease

Anti-proliferative agents have been the primary therapeutic drug of choice to inhibit restenosis after endovascular treatment. However, recent safety and efficacy concerns for patients who underwent peripheral artery disease revascularization have demonstrated the need for alternative therapeutics. The aim of this investigation was to investigate the efficacy of a cell-specific RNA aptamer inhibiting vascular smooth muscle cell proliferation and migration. First, the impact of the RNA aptamer (Apt 14) on the wound healing of primary cultured porcine vascular smooth muscle cells (VSMCs) was examined in response to a scratch wound injury. We then evaluated the effect of local luminal delivery of Apt 14 on neointimal formation in a clinically relevant swine iliofemoral injury model. In contrast with a non-selected control aptamer (NSC) that had no impact on VSMC migration, Apt 14 attenuated the wound healing of primary cultured porcine VSMCs to platelet-derived growth factor-BB. Histological analysis of the Apt 14-treated arteries demonstrated a significant reduction in neointimal area percent diameter stenosis compared with arteries treated with saline and NSC controls. The findings of this study suggest that aptamers can function as selective inhibitors and thus provide more fine-tuning to inhibit selective pathways responsible for neointimal hyperplasia.

Precision delivery of liquid therapy into the arterial wall for the treatment of peripheral arterial disease

Perfusion catheters have recently emerged as a novel approach to deliver liquid anti-proliferative agents into flow obstructed arterial segments. The purpose of this study was to determine the impact of luminal delivery pressure on liquid drug penetration into the vessel wall. An ex vivo model using harvested porcine carotid arteries and a two-dimensional computational model were utilized to determine the impact of delivery pressure of liquid therapy into the arterial wall. A pig peripheral injury model determined the impact of intra-luminal delivery pressure on drug retention. Ex vivo results demonstrated that depth of fluid penetration varies from 6.93 ± 1.90% at 0 atm to 27.75 ± 6.61% penetration of the medial layer at 0.4 atm. Computational results had similar outcomes, as penetration varied between 4.4% and 22.84%. The in vivo results demonstrated significant increase in drug delivery to the arterial tissue at 0.4 atm versus 0.1 atm at 1 h (23.43 ± 13.59 ng/mg vs. 2.49 ± 1.81 ng/mg, p = 0.026) and 7 days (0.50 ± 0.39 ng/mg vs. 0.018 ± 0.023 ng/mg, p = 0.0496). The result of this study provides an innovative strategic and technical approach to enable targeted liquid therapy.

Percutaneous treatment of vascular access-site complications: a ten years' experience in two centres

Background

The spread of percutaneous arterial catheterization in diagnostic and therapeutic procedures has led to a parallel increase of vascular access site complications. The incidence of these events is between 0.2–1%. A detailed analysis of injuries by type of procedure shows a higher incidence of injuries after therapeutic procedures (3%) than those observed for diagnostic ones (1%), due to the greater size of the vascular devices used and the necessity to frequently administer anticoagulant and antiplatelet therapy during procedures. The iatrogenic arterial injuries requiring treatment are the pseudoaneurysm, arteriovenous fistula, arterial rupture and dissection. Less frequent complications include distal embolization of the limbs, nerve damage, abscess and lymphocele.

Moreover, the use of percutaneous vascular closure devices (VCD) has further expanded the types of complications, with an increased risk of stenosis, thrombosis, distal embolism and infection. Our work aims to bring the personal 10 years’ experience in the percutaneous treatment of vascular access-site complications.

Results

Ninety-two pseudoaneurysms (PSA), 12 arteriovenous fistulas (AVF), 15 retrograde dissections (RD) and 11 retroperitoneal bleedings (RB) have been selected and treated. In 120/130 cases there were no periprocedural complications with immediate technical success (92.3%). Nine femoral PSA, treated with percutaneous ultrasound-guided thrombin injection, showed a failure to close the sac and therefore they were treated by PTA balloon inflation with a contralateral approach and cross-over technique. Only one case of brachial dissection, in which the prolonged inflation of the balloon has not led to a full reimbursement of the dissection flap, was then surgically repaired. At the 7 days follow-up, complications were two abscesses in retroperitoneal bleedings, treated by percutaneous drainage. At 3 months, acute occlusion of 3 covered femoral stents occurred, then treated by loco-regional thrombolysis and PTA. A total of 18 major complications was recorded at 2 years, with a complication rate at 2 years of 13.8%.

Conclusions

The percutaneous treatment of vascular access-site complications is the first-choice treatment. It represents a safe and effective option, validated by a high technical success rate and a low long-term complication rate, that allows avoiding the surgical approach in most cases.

Pre-Clinical Investigation of Keratose as an Excipient of Drug Coated Balloons

BACKGROUND

Drug-coated balloons (DCBs), which deliver anti-proliferative drugs with the aid of excipients, have emerged as a new endovascular therapy for the treatment of peripheral arterial disease. In this study, we evaluated the use of keratose (KOS) as a novel DCB-coating excipient to deliver and retain paclitaxel.

METHODS

A custom coating method was developed to deposit KOS and paclitaxel on uncoated angioplasty balloons. The retention of the KOS-paclitaxel coating, in comparison to a commercially available DCB, was evaluated using a novel vascular-motion simulating ex vivo flow model at 1 h and 3 days. Additionally, the locoregional biological response of the KOS-paclitaxel coating was evaluated in a rabbit ilio-femoral injury model at 14 days.

RESULTS

The KOS coating exhibited greater retention of the paclitaxel at 3 days under pulsatile conditions with vascular motion as compared to the commercially available DCB (14.89 ± 4.12 ng/mg vs. 0.60 ± 0.26 ng/mg, p = 0.018). Histological analysis of the KOS-paclitaxel-treated arteries demonstrated a significant reduction in neointimal thickness as compared to the uncoated balloons, KOS-only balloon and paclitaxel-only balloon.

CONCLUSIONS

The ability to enhance drug delivery and retention in targeted arterial segments can ultimately improve clinical peripheral endovascular outcomes.

The use of an occlusion perfusion catheter to deliver paclitaxel to the arterial wall

AIM

Nonstent drug delivery platforms have recently emerged as an alternative treatment of peripheral arterial disease. Perfusion catheters have the potential to directly deliver antiproliferative agents to the medial arterial layer to prevent restenosis. The purpose of this study was to therefore determine the effectiveness of a perfusion catheter to deliver paclitaxel, a proven antiproliferative agent, to combat restenosis.

METHODS

A benchtop model was utilized to determine the varying parameters of a novel occlusion perfusion catheter to maximize paclitaxel delivery using pharmacokinetic evaluation and fluorescent microscopy. Parameters tested included concentration of paclitaxel, delivery pressure, duration of delivery, and the use of an excipient. In addition, bilateral rabbit iliac arteries were treated with the perfusion catheter and pharmacokinetic evaluation performed at 1 hour, 1 day and 3 days.

RESULTS

Benchtop testing demonstrated uniform and circumferential penetration of paclitaxel within the treated arteries. The results of the ex vivo test identified two groups with and without an excipient with similar loading conditions (with excipient: 15.4±8.6 ng/mg vs without excipient: 8.9±6.9 ng/mg, P=.77). The in vivo pharmacokinetic analysis of these two groups demonstrated the use of contrast agent increased arterial paclitaxel levels and maintained initial paclitaxel dosing up to 3 days (With excipient: 1 hour: 107±62 ng vs 3 days: 40±23 ng, P=.824; No excipient: 1 hour: 247±120 ng vs 3 days: 2.92±2.9 ng, P=.009).

CONCLUSIONS

These results demonstrate the feasibility to deliver paclitaxel directly to the medial layer of an artery via a perfusion catheter.

[Distal revascularization in diabetic patients with chronic limb ischemia]

Diabetes mellitus is an independent risk factor for peripheral artery disease. Life expectancy is 41 months for diabetic patients with an ischemic ulcer. The characteristics of diabetic arteriopathy make its treatment more difficult than in non-diabetic patients. Few data are available about the surgical treatment of arteriopathy in diabetic patients (including angioplasty or bypass), especially in case of distal arteriopathy. The choice of the procedure depends on multiple factors such as the disease localization, its extent, distal blood flow and vascular disease-related surgical risk. The principal aim of revascularisation is to restore direct flow to the foot in order to ensure wound healing and limb salvage. With percutaneous endoluminal angioplasty, limb salvage can be achieved in more than 80% of patients at 1-3 years. The percutaneous procedure is less invasive than open surgery, there are fewer complications, and morbidity and mortality rates are reduced; moreover, a second procedure remains possible in the future. With bypass surgery, the rate of limb salvage exceeds 80% at five years. Nevertheless, peri-operative mortality reaches 3% and arterial anatomy, patient-related risks factors or venous graft availability may be limitations. New endovascular techniques especially designed for the distal arteries of the lower limbs enable very distal revascularization with morbidity and mortality rates lower than with surgery.

Bayesian network meta-analysis of nitinol stents, covered stents, drug-eluting stents, and drug-coated balloons in the femoropopliteal artery

OBJECTIVE

Several randomized controlled trials (RCTs) have shown the superiority of some of these technologies over balloon angioplasty, but direct comparisons between these treatment options are lacking. The authors conducted a network meta-analysis of RCTs comparing bare nitinol stents, covered nitinol stents, paclitaxel- or sirolimus-eluting stents (PES or SES), and paclitaxel-coated balloons (PCB) with plain balloon angioplasty or with each other in the femoropopliteal artery (PROSPERO registry: CRD42013004845).

METHODS

Sixteen RCTs comprising 2532 patients with 4227 person-years of follow-up were analyzed on an intention-to-treat basis. Bayesian random effects Poisson and binomial models were used for mixed treatment comparisons (WinBUGS). Clinical heterogeneity was accounted for by incorporating a meta-regression model on trial-specific baseline risk. End points included technical success, vascular restenosis, target lesion revascularization, and major amputations. Pairwise odds ratios and rate ratios (ORs and RRs) of absolute treatment effects were calculated, and the probabilities of each treatment being best are reported. Summary estimates are reported as the posterior median and associated credible intervals (CrIs) that serve the same purpose as confidence intervals in the context of the Bayesian framework. Extensive sensitivity, meta-regression, and network consistency analyses were performed to evaluate heterogeneity.

RESULTS

Technical success was highest with covered stents (pooled OR, 13.6; 95% CrI, 3.3-31.1, probability best 82%) followed by uncovered stents (pooled OR, 7.0; 95% CrI, 2.6-129, probability best 18%) when compared with balloon angioplasty (reference treatment). Vascular restenosis was lowest with PES (RR, 0.43; 95% CrI, 0.16-1.18, probability best 45%) followed by PCB (RR, 0.43; 95% CrI, 0.26-0.67, probability best 42%). Target lesion revascularization was lowest with PCB (RR, 0.36; 95% CrI, 0.23-0.55, probability best 56%) followed by PES (RR, 0.42; 95% CrI, 0.16-1.06, probability best 33%). Major amputations were rare in all treatment and control groups (pooled amputation rate of 0.7 events per 100 person-years).

CONCLUSIONS

Immediate technical success is better with the use of covered stents, whereas paclitaxel-eluting stents and paclitaxel-coated balloons offer the best long-term results in the femoropopliteal artery.

Emerging stent and balloon technologies in the femoropopliteal arteries

Endovascular procedures for the management of the superficial femoral (SFA) and popliteal artery disease are increasingly common. Over the past decade, several stent technologies have been established which may offer new options for improved clinical outcomes. This paper reviews the current evidence for SFA and popliteal artery angioplasty and stenting, with a focus on randomized trials and registries of nitinol self-expanding stents, drug-eluting stents, dug-coated balloons, and covered stent-grafts. We also highlight the limitations of the currently available data and the future routes in peripheral arterial disease (PAD) stent and balloon technology.