Stent revascularization versus bypass surgery for peripheral artery disease in type 2 diabetic patients - an instrumental variable analysis

Therapeutic Potential for Beta-3 Adrenoreceptor Agonists in Peripheral Arterial Disease and Diabetic Foot Ulcers

Annually, peripheral arterial disease is estimated to cost over USD 21 billion and diabetic foot disease an estimated at USD 9-13 billion. Mirabegron is a TGA-approved beta-3 adrenoreceptor agonist, shown to be safe and effective in the treatment of overactive bladder syndrome by stimulating bladder smooth muscle relaxation. In this review, we discuss the potential use of beta-3 adrenoreceptor agonists as therapeutic agents repurposed for peripheral arterial disease and diabetic foot ulcers. The development of both conditions is underpinned by the upregulation of oxidative stress pathways and consequential inflammation and hypoxia. In oxidative stress, there is an imbalance of reactive oxygen species and nitric oxide. Endothelial nitric oxide synthase becomes uncoupled in disease states, producing superoxide and worsening oxidative stress. Agonist stimulation of the beta-3 adrenoreceptor recouples and activates endothelial nitric oxide synthase, increasing the production of nitric oxide. This reduces circulating reactive oxygen species, thus decreasing redox modification and dysregulation of cellular proteins, causing downstream smooth muscle relaxation, improved endothelial function and increased angiogenesis. These mechanisms lead to endothelial repair in peripheral arterial disease and an enhanced perfusion in hypoxic tissue, which will likely improve the healing of chronic ulcers.

A review on femoropopliteal arterial deformation during daily lives and nickel-titanium stent properties

The increasing number of studies on the behaviour of stent placement in recent decades provides a clear understanding of peripheral artery disease (PAD). The severe mechanical loads (axial tension and compression, bending, radial compression and torsion) deformation of the femoropopliteal artery (FPA) is responsible for the highest failure rate of permanent nickel-titanium (Nitinol) stents. Therefore, the purpose of this article is to review research papers that examined the deformation of the natural load environment of FPA, the properties of Nitinol and mechanical considerations. In conclusion, a better understanding of mechanical behaviour for FPA Nitinol stents contributes to increased mechanical performance and fatigue-life.

Supera Stent for Management of Occlusive Popliteal Artery Disease: an Indian Experience

Introduction

Popliteal artery occlusion is common in elderly, smokers, and patients with diabetes, with globally rising incidence. Angioplasty and stenting are common treatment options available to manage lower limb occlusive diseases. As popliteal artery experiences high biomechanical stress, Supera stent is designed to reduce the risk of stent fractures and for better patency across the knee joint.

Aim & Objectives

The aim of this study is to evaluate the Supera stent in the management of popliteal artery occlusive disease. The objectives of this study are (1) to evaluate the efficacy of Supera stent in the management of popliteal artery occlusive disease and (2) to prove it as a relatively safe to use option.

Material & Methods

Patients who underwent stent implantation in popliteal artery were analyzed with regular/serial follow-up. Critical limb ischemia and intermittent claudication patients were included. Medical records, radiographs, and procedural data were examined. The patients were classified according to Trans-Atlantic Inter Society Consensus II criteria. The femoropopliteal lesions which were classified into TASC B and C categories were included in the study. Stents of 5 mm and 5.5 mm diameter and with various lengths were used to treat all the patients.

Results

A total number of patients with tissue loss and rest pain analyzed were eighty-six and all of them were treated by implanting stents in popliteal artery. In 71.4% of cases, the lesions were found in the proximal segment of the artery. In nearly 95% of cases, technical success was achieved with the use of single stent. The primary and assisted primary patency rates at 24 months were found to be 86.04% and 95.34%, respectively. Notwithstanding the stent placement at a region of high biomechanical stress, there was no case of stent fracture. The limb salvage rate was 100%. The patients who died due to unrelated causes within 90 days of procedure were two.

Conclusion

The present study demonstrated that Supera stent is a safe and effective procedure for treating claudication and limb ischemia due to popliteal artery disease.

Comparison of morphometric, structural, mechanical, and physiologic characteristics of human superficial femoral and popliteal arteries

Peripheral arterial disease differentially affects the superficial femoral (SFA) and the popliteal (PA) arteries, but their morphometric, structural, mechanical, and physiologic differences are poorly understood. SFAs and PAs from 125 human subjects (age 13-92, average 52±17 years) were compared in terms of radii, wall thickness, and opening angles. Structure and vascular disease were quantified using histology, mechanical properties were determined with planar biaxial extension, and constitutive modeling was used to calculate the physiologic stress-stretch state, elastic energy, and the circumferential physiologic stiffness. SFAs had larger radii than PAs, and both segments widened with age. Young SFAs were 5% thicker, but in old subjects the PAs were thicker. Circumferential (SFA: 96→193°, PA: 105→139°) and longitudinal (SFA: 139→306°, PA: 133→320°) opening angles increased with age in both segments. PAs were more diseased than SFAs and had 11% thicker intima. With age, intimal thickness increased 8.5-fold, but medial thickness remained unchanged (620μm) in both arteries. SFAs had 30% more elastin than the PAs, and its density decreased ~50% with age. SFAs were more compliant than PAs circumferentially, but there was no difference longitudinally. Physiologic circumferential stress and stiffness were 21% and 11% higher in the SFA than in the PA across all ages. The stored elastic energy decreased with age (SFA: 1.4→0.4kPa, PA: 2.5→0.3kPa). While the SFA and PA demonstrate appreciable differences, most of them are due to vascular disease. When pathology is the same, so are the mechanical properties, but not the physiologic characteristics that remain distinct due to geometrical differences.

Editor's Choice - Long Term Survival after Femoropopliteal Artery Revascularisation with Paclitaxel Coated Devices: A Propensity Score Matched Cohort Analysis

OBJECTIVE

The aim of this study was to determine the survival of patients after use of paclitaxel coated devices (PCX), as a recent meta-analysis of randomised trials reported higher mortality in patients treated with PCX balloons and stents METHODS: A retrospective health insurance claims analysis of patients covered by the second largest insurance fund in Germany, BARMER, was used to identify index femoropopliteal arterial interventions between 1 January 2010 and 31 December 2018. To ensure first PCX exposure, patients with prior deployment of PCX were excluded. The study cohort was stratified into patients with chronic limb threatening ischaemia (CLTI) and intermittent claudication (IC), then into balloons vs. stents cohorts. Within each stratum PCX were compared with uncoated devices. Propensity score matching was used to balance the study groups. Survival was evaluated using the Kaplan-Meier method and Cox regression.

RESULTS

There were 37 914 patients (mean age 73.3 years; 48.8% female) included in the study. The annual proportion of PCX use increased from 3% to 39% during the study period for CLTI and from 4% to 48% for IC (both p < .001). Paclitaxel coated balloons and stents were associated with improved overall survival (hazard ratio [HR] 0.83, 95% confidence interval [CI] 0.77-0.90), amputation free survival (HR 0.85, 95% CI 0.78-0.91), and freedom from major cardiovascular events (HR 0.82, 95% CI 0.77-0.89) vs. uncoated devices at five years for CLTI. In IC cohort, mortality was significantly lower after using drug coated balloons (DCB) (HR 0.87, 95% CI 0.76-0.99) or combined DCB and drug eluting stents (HR 0.88, 95% CI 0.80-0.98).

CONCLUSION

In this large health insurance claims analysis, rapid adoption of PCX, higher long term survival, better amputation free survival, and lower rates of major cardiovascular events were seen after their use for the treatment of CLTI.

A Novel, Individualized Exercise Program for Patients with Peripheral Arterial Disease Recovering from Bypass Surgery

The effectiveness of an individual six-month-long physical exercise program in improving health-related quality of life (HRQOL) is unclear. There is some evidence that an individual exercise program can be effective for this aim. The goal of this study was to compare an individual six-month-long physical exercise program for patients with PAD (Peripheral Arterial Disease) with a traditional exercise program and find the effect of these programs on HRQOL and PAD risk factors. The study included patients who underwent femoral–popliteal artery bypass grafting surgery. Patients were divided into three groups: patients participating in an individual six-month-long physical exercise program (group I), in the standard physical activity program (group II), and in a control group (group III), with no subjects participating in rehabilitation II. Results: group I patients had a significantly (p < 0.001) higher HRQOL at 6 months after their surgery compared with groups II and III. The HRQOL scores were significantly (p < 0.05) lower after surgery among older (≥ 65), overweight participants, as well as among patients with diabetes mellitus and cardiovascular diseases when comparing study results with patients without these risk factors.

Nanoparticles for Detection and Treatment of Peripheral Arterial Disease

Peripheral arterial disease (PAD) is defined as a slow, progressive disorder of the lower extremity arterial vessels characterized by chronic narrowing that often results in occlusion and is associated with loss of functional capacity. Although the PAD occurrence rate is increasing in the elderly population, outcomes with current treatment strategies are suboptimal. Hence, there is an urgent need to develop new technologies that overcome limitations of traditional modalities for PAD detection and therapy. In this Review, the application of nanotechnology as a tool that bridges the gap in PAD diagnosis and therapy is in focus. Several materials including synthetic, natural, biodegradable, and biocompatible materials are used to develop nanoparticles for PAD diagnostic and/or therapeutic applications. Moreover, various recent research approaches are being explored to diagnose PAD through multimodality imaging with different nanoplatforms. Further efforts include targeted delivery of various therapeutic agents using nanostructures as carriers to treat PAD. Last, but not least, despite being a fairly new field, researchers are exploring the use of nanotheranostics for PAD detection and therapy.

Nitinol Stents in the Femoropopliteal Artery: A Mechanical Perspective on Material, Design, and Performance

Endovascular stenting has matured into a commonly used treatment for peripheral arterial disease (PAD) due to its minimally invasive nature and associated reductions in short-term morbidity and mortality. The mechanical properties of the superelastic Nitinol alloy have played a major role in the explosion of peripheral artery stenting, with modern stents demonstrating reasonable resilience and durability. Yet in the superficial femoral and popliteal arteries, even the newest generation Nitinol stents continue to demonstrate clinical outcomes that leave significant room for improvement. Restenosis and progression of native arterial disease often lead to recurrence of symptoms and reinterventions that increase morbidity and health care expenditures. One of the main factors thought to be associated with stent failure in the femoropopliteal artery (FPA) is the unique and highly dynamic mechanical environment of the lower limb. Clinical and experimental data demonstrate that the FPA undergoes significant deformations with limb flexion. It is hypothesized that the inability of many existing stent designs to conform to these deformations likely plays a role in reconstruction failure, as repetitive movements of the leg and thigh combine with mechanical mismatch between the artery and the stent and result in mechanical damage to both the artery and the stent. In this review we will identify challenges and provide a mechanical perspective of FPA stenting, and then discuss current research directions with promise to provide a better understanding of Nitinol, specific features of stent design, and improved characterization of the biomechanical environment of the FPA to facilitate development of better stents for patients with PAD.