Alginate-Encapsulated Mesenchymal Stromal Cells Improve Hind Limb Ischemia in a Translational Swine Model

BACKGROUND

Cellular therapies have been investigated to improve blood flow and prevent amputation in peripheral artery disease with limited efficacy in clinical trials. Alginate-encapsulated mesenchymal stromal cells (eMSCs) demonstrated improved retention and survival and promoted vascular generation in murine hind limb ischemia through their secretome, but large animal evaluation is necessary for human applicability. We sought to determine the efficacy of eMSCs for peripheral artery disease-induced limb ischemia through assessment in our durable swine hind limb ischemia model.

METHODS AND RESULTS

Autologous bone marrow eMSCs or empty alginate capsules were intramuscularly injected 2 weeks post-hind limb ischemia establishment (N=4/group). Improvements were quantified for 4 weeks through walkway gait analysis, contrast angiography, blood pressures, fluorescent microsphere perfusion, and muscle morphology and histology. Capsules remained intact with mesenchymal stromal cells retained for 4 weeks. Adenosine-induced perfusion deficits and muscle atrophy in ischemic limbs were significantly improved by eMSCs versus empty capsules (mean±SD, 1.07±0.19 versus 0.41±0.16, P=0.002 for perfusion ratios and 2.79±0.12 versus 1.90±0.62 g/kg, P=0.029 for ischemic muscle mass). Force- and temporal-associated walkway parameters normalized (ratio, 0.63±0.35 at week 3 versus 1.02±0.19 preligation; P=0.17), and compensatory footfall patterning was diminished in eMSC-administered swine (12.58±8.46% versus 34.85±15.26%; P=0.043). Delivery of eMSCs was associated with trending benefits in collateralization, local neovascularization, and muscle fibrosis. Hypoxia-cultured porcine mesenchymal stromal cells secreted vascular endothelial growth factor and tissue inhibitor of metalloproteinase 2.

CONCLUSIONS

This study demonstrates the promise of the mesenchymal stromal cell secretome at improving peripheral artery disease outcomes and the potential for this novel swine model to serve as a component of the preclinical pipeline for advanced therapies.

Structural and Mechanical Properties of Human Superficial Femoral and Popliteal Arteries

The femoropopliteal artery (FPA) is the main artery in the lower limb. It supplies blood to the leg muscles and undergoes complex deformations during limb flexion. Atherosclerotic disease of the FPA (peripheral arterial disease, PAD) is a major public health burden, and despite advances in surgical and interventional therapies, the clinical outcomes of PAD repairs continue to be suboptimal, particularly in challenging calcified lesions and biomechanically active locations. A better understanding of human FPA mechanical and structural characteristics in relation to age, risk factors, and the severity of vascular disease can help develop more effective and longer-lasting treatments through computational modeling and device optimization. This review aims to summarize recent research on the main biomechanical and structural properties of human superficial femoral and popliteal arteries that comprise the FPA and describe their anatomy, composition, and mechanical behavior under different conditions.

Efficiency and safety of dual pathway inhibition for the prevention of femoropopliteal artery restenosis in repeated endovascular interventions

OBJECTIVE

There is a lack of consensus regarding the optimal strategy for evaluating the efficiency and safety of dual-pathway inhibition (DPI) in preventing femoropopliteal restenosis in patients undergoing repeated endovascular interventions. Despite several therapeutic interventions available for preventing femoropopliteal restenosis post repeated endovascular interventions, the ideal strategy, particularly evaluating the efficacy and safety of DPI, remains a matter of debate.

METHODS

From January 2015 to September 2021, patients who underwent repeated endovascular interventions for femoropopliteal restenosis were compared with those who underwent DPI or dual antiplatelet therapy (DAPT) after surgery using a propensity score-matched analysis. The primary outcome was clinically driven target lesion revascularization (CD-TLR). The principal safety outcome was a composite of major bleeding and clinically relevant non-major (CRNM) bleeding. To further enhance the rigor, Kaplan-Meier plots, Cox proportional hazards modeling, and sensitivity analyses, as well as subgroup analyses were employed, reducing potential confounders.

RESULTS

A total of 441 patients were included in our study, of whom 294 (66.7%) received DAPT and 147 (33.1%) received DPI, with 114 matched pairs (mean age, 72.21 years; 84.2% male). Cumulative probability of CD-TLR at 36 months in the DPI group (17%) trended lower than that in the DAPT group (32%) (hazard ratio [HR], 0.45; 95% confidence interval [CI], 0.26-0.78; P =.004). The cumulative probability of freedom from CD-TLR at 36 months in the DPI group was 83%. No significant difference was observed in the composite outcome of major or CRNM bleeding between the DPI and DAPT groups (HR, 1.26; 95% CI, 0.34 to 4.69; P = .730). The DPI group was associated with significantly lower rates of CD-TLR in the main subgroup analyses of diabetes (P = .001), previous smoking history (P = .008), longer lesion length (>10 cm) (P = .003), and treatment with debulking strategy (P = .003).

CONCLUSIONS

In our investigation focused on CD-TLR, we found that DPI exhibited a significant reduction in the risk of reintervention compared with other treatment modalities. This underscores the potential of DPI as a viable therapeutic strategy in preventing reinterventions. Moreover, our assessment of safety outcomes revealed that the bleeding risks associated with DPI were on par with DAPT, thereby not compromising patient safety. These findings pave the way for potential broader clinical implications, emphasizing the effectiveness and safety of DPI in the context of reducing reintervention risks.

A New Drug-Coated Balloon for the Treatment of Superficial Femoropopliteal Artery Disease: 12-Month Results from the IN-DEPT SFA Trial

PURPOSE

To report the outcomes of the IN-DEPT trial assessing the feasibility, preliminary safety data, and 12-month outcomes of a new drug-coated balloon (DCB) product for peripheral artery disease (PAD) in Chinese patients.

MATERIALS AND METHODS

This is a prospective, multicenter, single-arm clinical trial. A total of 160 patients with superficial femoral artery (SFA) and/or proximal popliteal artery lesions were treated with a new paclitaxel-coated DCB. The preliminary effectiveness end point was 12-month primary patency. The primary safety end point was freedom from device- and procedure-related mortality over 30 days and freedom from major target limb amputation and clinically driven target lesion revascularization (CD-TLR) within 12 months after the index procedure.

RESULTS

In total, 160 patients presented with 162 target lesions. A total of 139 lesions (85.8%) were treated with 1 DCB, whereas the other 23 lesions (14.2%) were treated with 2 devices. The device success rate was 100%. A total of 135 subjects reached the preliminary effectiveness end point, with a 12-month primary patency rate of 84.4%. There was no 30-day device- or procedure-related death or unplanned major target limb amputation at 12 months. Five CD-TLRs (3.1%) occurred during the 12-month follow-up period.

CONCLUSIONS

Results from the IN-DEPT SFA trial showed satisfactory feasibility and safety of the new DCB over 12 months in Chinese patients with PAD and femoropopliteal de novo lesions, including both stenoses and total occlusions.

Longitudinal Magnetic Resonance Imaging-Based Superficial Femoral Artery Velocity Measurements in Diabetic and Nondiabetic Patients With Peripheral Artery Disease

BACKGROUND

Longitudinal associations of noninvasive 2-dimensional phase-contrast magnetic resonance imaging (2D-PC-MRI) velocity markers of the superficial femoral artery (SFA) were analyzed along with the characteristics of peripheral artery disease (PAD). We hypothesized that the 2-year differences in MRI-based measures of SFA velocity were associated with longitudinal changes in markers of PAD.

METHODS

A total of 33 (11 diabetic, 22 nondiabetic) patients with PAD with baseline and 2-year follow-up MRI scans were included in this secondary analysis of the Effect of Lipid Modification on Peripheral Artery Disease after Endovascular Intervention Trial (ELIMIT). Electrocardiographically gated 2D-PC-MRI was performed at a proximal and a distal location of the distal SFA territory. SFA lumen, wall, and total vessel volumes and the normalized wall index (NWI) were analyzed.

RESULTS

Baseline characteristics did not differ between diabetic and nondiabetic PAD patients. Maximum proximal and distal SFA velocity measures did not differ between baseline and 2 years (41.98 interquartile range (IQR) (23.58-72.6) cm/s vs. 40.31 IQR (26.69-61.29) cm/s; P = 0.30). Pooled analysis (N = 33) showed that the 24-month change in the NWI was inversely associated with the 24-month change in the proximal maximal SFA velocity (beta = -168.36, R2 = 0.150, P value = 0.03). The 24-month change of the maximum velocity differences between the proximal and distal SFA locations was inversely associated with the 24-month changes in peak walking distance (beta = -0.003, R2 = 0.360, P value = 0.011).

CONCLUSION

The 2-year change of SFA plaque burden is inversely associated with the 2-year change of proximal peak SFA blood flow velocity. 2D-PC-MRI measured SFA velocity may be of interest in assessing PAD longitudinally.

Disease Specific Health Related Quality of Life in Patients With Chronic Limb Threatening Ischaemia Undergoing Revascularisation of Femoropopliteal Lesions

OBJECTIVE

Patients with chronic limb threatening ischaemia (CLTI) suffer from pain and non-healing ulcers, which impact negatively on both their physical and mental health. While maintaining and improving quality of life is a principal aim with all treatments, little is known about the health related quality of life (HRQoL) of CLTI patients and how revascularisation procedures impact on HRQoL endpoints. The aim of this study was to investigate disease specific HRQoL before and after revascularisation in patients with CLTI undergoing femoropopliteal revascularisation.

METHODS

HRQoL was prospectively analysed in 190 CLTI patients with main atherosclerotic target lesions in the femoropopliteal segment, who were planned for endovascular or open revascularisation. The choice of revascularisation method was made by the vascular team, represented by both open and endovascular expertise. The Vascular Quality of Life (VascuQoL) questionnaire was used to assess disease specific HRQoL before revascularisation and one month, one year, and two years after the procedure. Main endpoints were mean VascuQoL score changes, effect sizes of observed changes and the proportion reaching a minimally important difference (half a standard deviation change from baseline) during two years after revascularisation.

RESULTS

Patient reported VascuQoL scores were low at baseline (mean 2.68, 95% CI 1.18 - 4.17). After revascularisation, the mean VascuQoL score improved statistically significantly over time, with the largest improvement observed after one year (difference from baseline 2.02, 95% CI 1.75 - 2.29; p < .001). No differences in HRQoL change over time were observed between patients treated with endovascular approaches compared with bypass surgery. Approximately half the patients reached the minimally important threshold at one year (53%), which was largely maintained also at two years (41%).

CONCLUSION

While CLTI profoundly affected HRQoL, a large and clinically meaningful HRQoL increase was observed after revascularisation. This confirms the value of CLTI revascularisation on HRQoL and underlines the importance of including patient reported outcomes when evaluating revascularisation procedures in CLTI patients.

microRNA-29a Regulates ADAM12 Through Direct Interaction With ADAM12 mRNA and Modulates Postischemic Perfusion Recovery

Background Peripheral artery disease is caused by atherosclerotic occlusion of vessels outside the heart and most commonly affects vessels of the lower extremities. Angiogenesis is a part of the postischemic adaptation involved in restoring blood flow in peripheral artery disease. Previously, in a murine hind limb ischemia model of peripheral artery disease, we identified ADAM12 (a disintegrin and metalloproteinase gene 12) as a key genetic modifier of postischemic perfusion recovery. However, less is known about ADAM12 regulation in ischemia. MicroRNAs are a class of small, noncoding, single-stranded RNAs that regulate gene expression primarily through transcriptional repression of messenger RNA (mRNA). We showed microRNA-29a (miR-29a) modulates ADAM12 expression in the setting of diabetes and ischemia. However, how miR-29a modulates ADAM12 is not known. Moreover, the physiological effects of miR-29a modulation in a nondiabetic setting is not known. Methods and Results We overexpressed or inhibited miR-29a in ischemic mouse gastrocnemius and tibialis anterior muscles, and quantified the effect on perfusion recovery, ADAM12 expression, angiogenesis, and skeletal muscle regeneration. In addition, using RNA immunoprecipitation-based anti-miR competitive assay, we investigated the interaction of miR-29a and ADAM12 mRNA in mouse microvascular endothelial cell, skeletal muscle, and human endothelial cell lysates. Ectopic expression of miR-29a in ischemic mouse hind limbs decreased ADAM12 mRNA expression, increased skeletal muscle injury, decreased skeletal muscle function, and decreased angiogenesis and perfusion recovery, with no effect on skeletal muscle regeneration and myofiber cross-sectional area following hind limb ischemia. RNA immunoprecipitation-based anti-miR competitive assay studies showed miR-29a antagomir displaced miR-29a and ADAM12 mRNA from the AGO-2 (Argonaut-2) complex in a dose dependent manner. Conclusions Taken together, the data show miR-29a suppresses ADAM12 expression by directly binding to its mRNA, resulting in impaired skeletal muscle function, angiogenesis, and poor perfusion. Hence, elevated levels of miR-29a, as seen in diabetes and aging, likely contribute to vascular pathology, and modulation of miR-29a could be a therapeutic target.

Systematic review of atherectomy of inguinal arteries for atherosclerotic lesions

INTRODUCTION

Surgical endarterectomy represents the gold standard for the treatment of atherosclerotic lesions of the groin vessels. Endovascular treatment such as atherectomy with or without drug coated angioplasty (DCA) of the so called no stenting zones, i.e. inguinal and popliteal vessels, is gaining growing acceptance as alternative option to open surgery. This systematic review aims to scrutiny the current clinical evidence regarding atherectomy and DCA for the common artery (CFA).

EVIDENCE ACQUISITION

We conducted an exhaustive research in multiple platforms (Medline, PubMed, Cochrane, Google Scholar, Embase) on studies over atherectomy and angioplasty for inguinal atherosclerotic lesions published between 2000 and 2021. As search strategy we used a wide list of MeSH items, words, synonyms. Bibliographies of review articles were checked for further relating studies regarding atherectomy of CFA. A qualitative and quantitative data analysis was carried out.

EVIDENCE SYNTHESIS

Fifteen studies were included in the qualitative review. Not all studies were focused only on atherectomy of inguinal vessels, despite including such treatment. Hence, data regarding this treatment were not exhaustive. A fairly homogeneous data analysis was possible in 7 of 15 studies. The remaining 8 studies were qualitatively analyzed but not included in the statistical analysis. In all 7 included studies directional atherectomy and DCA under filter protection were carried out. In this subgroup, overall, 497 patients were treated with atherectomy. Sixty-eight percent of the patients were males. Rutherford class from 1-3 dominated against 4-6 (63% vs. 37%). Mean technical success rate was 96%, with a primary and secondary patency rate of 92% and 98% respectively at one year. Procedure related vascular complications ranged from 1% to 6%.

CONCLUSIONS

Current literature about atherectomy for inguinal arteries is scant, data are inhomogeneous and so are treatment modalities. Nevertheless, the results of this systematic review suggest that this endovascular strategy is feasible with good short and midterm results. Prospective trials with larger patient cohorts are necessary to confirm these preliminary results.

Endothelial cell-derived pro-fibrotic factors increase TGF-β1 expression by smooth muscle cells in response to cycles of hypoxia-hyperoxia

BACKGROUND

The vascular pathology of peripheral artery disease (PAD) encompasses abnormal microvascular architecture and fibrosis in response to ischemia-reperfusion (I/R) cycles. We aimed to investigate the mechanisms by which pathological changes in the microvasculature direct fibrosis in the context of I/R.

METHODS

Primary human aortic endothelial cells (ECs) were cultured under cycles of normoxia-hypoxia (NH) or normoxia-hypoxia-hyperoxia (NHH) to mimic I/R. Primary human aortic smooth muscle cells (SMCs) were cultured and treated with media from the ECs.

FINDINGS

The mRNA and protein expression of the pro-fibrotic factors platelet derived growth factor (PDGF)-BB and connective tissue growth factor (CTGF) were significantly upregulated in ECs undergoing NH or NHH cycles. Treatment of SMCs with media from ECs undergoing NH or NHH cycles led to significant increases in TGF-β1, TGF-β pathway signaling intermediates, and collagen expression. Addition of neutralizing antibodies against PDGF-BB and CTGF to the media blunted the increases in TGF-β1 and collagen expression. Treatment of SMCs with PAD patient-derived serum also led to increased TGF-β1 levels.

INTERPRETATION

In an in-vitro model of I/R, which recapitulates the pathophysiology of PAD, increased secretion of PDGF-BB and CTGF by ECs was shown to be predominantly driving TGF-β1-mediated expression by SMCs. These cell culture experiments help elucidate the mechanism and interaction between ECs and SMCs in microvascular fibrosis associated with I/R. Thus, targeting these pro-fibrotic factors may be an effective strategy to combat fibrosis in response to cycles of I/R.

FUNDING

National Institute on Aging at the National Institutes of Health grant number R01AG064420.

RESEARCH IN CONTEXT

Evidence before this study: Previous studies in gastrocnemius biopsies from peripheral artery disease (PAD) patients showed that transforming growth factor beta 1 (TGF-β1), the most potent inducer of pathological fibrosis, is increased in the vasculature of PAD patients and correlated with collagen deposition. However, the exact cellular source of TGF-β1 remained unclear. Added value of this study: Exposing cells to cycles of normoxia-hypoxia-hyperoxia (NHH) resulted in pathological changes that are consistent with human PAD. This supports the idea that the use of NHH may be a reliable, novel in vitro model of PAD useful for studying associated pathophysiological mechanisms. Furthermore, pro-fibrotic factors (PDGF-BB and CTGF) released from endothelial cells were shown to induce a fibrotic phenotype in smooth muscle cells. This suggests a potential interaction between these cell types in the microvasculature that drives increased TGF-β1 expression and collagen deposition. Thus, targeting these pro-fibrotic factors may be an effective strategy to combat fibrosis in response to cycles of ischemia-reperfusion.

Twelve-Month Outcomes From the Japanese Post-Market Surveillance Study of the Viabahn Endoprosthesis as Treatment for Symptomatic Peripheral Arterial Disease in the Superficial Femoral Arteries

PURPOSE

To assess the midterm safety and effectiveness of the Gore® Viabahn® Endoprosthesis as treatment for symptomatic peripheral arterial disease (PAD) in the superficial femoral arteries (SFA).

MATERIALS AND METHODS

A prospective, multicenter, post-market surveillance study was conducted in Japan. Patients with symptomatic SFA lesions ≥ 10 cm and reference vessel diameters ranging from 4.0 to 7.5 mm were eligible for enrollment; patients with traumatic or iatrogenic vessel injury in the thoracic, abdominal, or pelvic arteries were excluded. Outcomes evaluated at 12 months were primary patency (PP), primary-assisted patency (PAP), secondary patency (SP), freedom from target lesion revascularization (fTLR), occurrence of device- or procedure-related serious adverse events (SAEs), and stent fractures.

RESULTS

From August 2016 to May 2017, 321 patients were enrolled at 64 Japanese sites (mean age, 73.9±8.7 years; 77.3% male). Hypertension, diabetes, and end stage renal disease were present in 84.4%, 54.8%, and 23.1% of patients, respectively. Mean lesion length was 23.6 cm±6.6 cm, with lesions ≥ 15 cm in 271 patients (84.4%). TASC C/D lesions accounted for 86.6% (39.1% TASC C, 47.5% TASC D); 26.5% had critical limb ischemia. Baseline ABI was 0.60±0.16. A total of 562 devices were implanted in 324 limbs, with a majority of patients (68.8%) receiving 2 stents. Through 12 months, 92.1% of patients were evaluable. Kaplan-Meier-estimated PP, PAP, and SP at 12 months was 85.6%, 91.7%, and 94.8%, respectively. Twelve-month fTLR was 92.3%. Mean change in ABI at 12 months was 0.343±0.21; mean improvement in Rutherford class was 2.5. Device- or procedure-related SAEs occurred in 3.1% through 30 days, with a majority of early SAEs consisting of access complications. Through 12 months, a cumulative 10.6% had device- or procedure-related SAEs, with the most common being device occlusions in 4.0%. Lower limb amputation occurred in 0.9% and was related to pre-existing ulceration or gangrene in all 3 cases. No stent fractures were observed at 12-month x-ray evaluation.

CONCLUSION

In a real-world Japanese patient population characterized by long SFA lesions and complex PAD, the Viabahn endoprosthesis was associated with excellent patency rates through 12 months and an acceptable safety profile.

Antioxidative and Angiogenic Hyaluronic Acid-Based Hydrogel for the Treatment of Peripheral Artery Disease

Peripheral arterial disease (PAD) is a progressive atherosclerotic disorder characterized by blockages of the arteries supplying the lower extremities. Ischemia initiates oxidative damage and mitochondrial dysfunction in the legs of PAD patients, causing injury to the tissues of the leg, significant decline in walking performance, leg pain while walking, and in the most severe cases, nonhealing ulcers and gangrene. Current clinical trials based on cells/stem cells, the trophic factor, or gene therapy systems have shown some promising results for the treatment of PAD. Biomaterial matrices have been explored in animal models of PAD to enhance these therapies. However, current biomaterial approaches have not fully met the essential requirements for minimally invasive intramuscular delivery to the leg. Ideally, a biomaterial should present properties to ameliorate oxidative stress/damage and failure of angiogenesis. Recently, we have created a thermosensitive hyaluronic acid (HA) hydrogel with antioxidant capacity and skeletal muscle-matching stiffness. Here, we further optimized HA hydrogels with the cell adhesion peptide RGD to facilitate the development of vascular-like structures in vitro. The optimized HA hydrogel reduced intracellular reactive oxygen species levels and preserved vascular-like structures against H₂O₂-induced damage in vitro. HA hydrogels also provided prolonged release of the vascular endothelial growth factor (VEGF). After injection into rat ischemic hindlimb muscles, this VEGF-releasing hydrogel reduced lipid oxidation, regulated oxidative-related genes, enhanced local blood flow in the muscle, and improved running capacity of the treated rats. Our HA hydrogel system holds great potential for the treatment of the ischemic legs of patients with PAD.

Diffusion tensor imaging indices of acute muscle damage are augmented after exercise in peripheral arterial disease

PURPOSE

Although it is known that peripheral arterial disease (PAD) is associated with chronic myopathies, the acute muscular responses to exercise in this population are less clear. This study used diffusion tensor imaging (DTI) to compare acute exercise-related muscle damage between PAD patients and healthy controls.

METHODS

Eight PAD patients and seven healthy controls performed graded plantar flexion in the bore of a 3T MRI scanner. Exercise began at 2 kg and increased by 2 kg every 2 min until failure, or completion of 10 min of exercise. DTI images were acquired from the lower leg pre- and post-exercise, and were analyzed for mean diffusivity, fractional anisotropy (FA), and eigenvalues 1-3 (λ1-3) of the medial gastrocnemius (MG) and tibialis anterior (TA).

RESULTS

Results indicated a significant leg by time interaction for mean diffusivity, explained by a significantly greater increase in diffusivity of the MG in the most affected legs of PAD patients (11.1 × 10-4 ± 0.5 × 10-4 mm2/s vs. 12.7 × 10-4 ± 1.2 × 10-4 mm2/s at pre and post, respectively, P = 0.02) compared to healthy control subjects (10.8 × 10-4 ± 0.3 × 10-4 mm2/s vs. 11.2 × 10-4 ± 0.5 × 10-4 mm2/s at pre and post, respectively, P = 1.0). No significant differences were observed for the TA, or λ1-3 (all P ≥ 0.06). Moreover, no reciprocal changes were observed for FA in either group (all P ≥ 0.29).

CONCLUSION

These data suggest that calf muscle diffusivity increases more in PAD patients compared to controls after exercise. These findings are consistent with the notion that acute exercise results in increased muscle damage in PAD.

Induced endothelial cells from peripheral arterial disease patients and neonatal fibroblasts have comparable angiogenic properties

Induced endothelial cells (iECs) generated from neonatal fibroblasts via transdifferentiation have been shown to have pro-angiogenic properties and are a potential therapy for peripheral arterial disease (PAD). It is unknown if iECs can be generated from fibroblasts collected from PAD patients and whether these cells are pro-angiogenic. In this study fibroblasts were collected from four PAD patients undergoing carotid endarterectomies. These cells, and neonatal fibroblasts, were transdifferentiated into iECs using modified mRNA. Endothelial phenotype and pro-angiogenic cytokine secretion were investigated. NOD-SCID mice underwent surgery to induce hindlimb ischaemia in a murine model of PAD. Mice received intramuscular injections with either control vehicle, or 1 × 106 neonatal-derived or 1 × 106 patient-derived iECs. Recovery in perfusion to the affected limb was measured using laser Doppler scanning. Perfusion recovery was enhanced in mice treated with neonatal-derived iECs and in two of the three patient-derived iEC lines investigated in vivo. Patient-derived iECs can be successfully generated from PAD patients and for specific patients display comparable pro-angiogenic properties to neonatal-derived iECs.

Effect of Low-Intensity vs High-Intensity Home-Based Walking Exercise on Walk Distance in Patients With Peripheral Artery Disease: The LITE Randomized Clinical Trial

IMPORTANCE

Supervised high-intensity walking exercise that induces ischemic leg symptoms is the first-line therapy for people with lower-extremity peripheral artery disease (PAD), but adherence is poor.

OBJECTIVE

To determine whether low-intensity home-based walking exercise at a comfortable pace significantly improves walking ability in people with PAD vs high-intensity home-based walking exercise that induces ischemic leg symptoms and vs a nonexercise control.

DESIGN, SETTING, AND PARTICIPANTS

Multicenter randomized clinical trial conducted at 4 US centers and including 305 participants. Enrollment occurred between September 25, 2015, and December 11, 2019; final follow-up was October 7, 2020.

INTERVENTIONS

Participants with PAD were randomized to low-intensity walking exercise (n = 116), high-intensity walking exercise (n = 124), or nonexercise control (n = 65) for 12 months. Both exercise groups were asked to walk for exercise in an unsupervised setting 5 times per week for up to 50 minutes per session wearing an accelerometer to document exercise intensity and time. The low-intensity group walked at a pace without ischemic leg symptoms. The high-intensity group walked at a pace eliciting moderate to severe ischemic leg symptoms. Accelerometer data were viewable to a coach who telephoned participants weekly for 12 months and helped them adhere to their prescribed exercise. The nonexercise control group received weekly educational telephone calls for 12 months.

MAIN OUTCOMES AND MEASURES

The primary outcome was mean change in 6-minute walk distance at 12 months (minimum clinically important difference, 8-20 m).

RESULTS

Among 305 randomized patients (mean age, 69.3 [SD, 9.5] years, 146 [47.9%] women, 181 [59.3%] Black patients), 250 (82%) completed 12-month follow-up. The 6-minute walk distance changed from 332.1 m at baseline to 327.5 m at 12-month follow-up in the low-intensity exercise group (within-group mean change, -6.4 m [95% CI, -21.5 to 8.8 m]; P = .34) and from 338.1 m to 371.2 m in the high-intensity exercise group (within-group mean change, 34.5 m [95% CI, 20.1 to 48.9 m]; P < .001) and the mean change for the between-group comparison was -40.9 m (97.5% CI, -61.7 to -20.0 m; P < .001). The 6-minute walk distance changed from 328.1 m at baseline to 317.5 m at 12-month follow-up in the nonexercise control group (within-group mean change, -15.1 m [95% CI, -35.8 to 5.7 m]; P = .10), which was not significantly different from the change in the low-intensity exercise group (between-group mean change, 8.7 m [97.5% CI, -17.0 to 34.4 m]; P = .44). Of 184 serious adverse events, the event rate per participant was 0.64 in the low-intensity group, 0.65 in the high-intensity group, and 0.46 in the nonexercise control group. One serious adverse event in each exercise group was related to study participation.

CONCLUSIONS AND RELEVANCE

Among patients with PAD, low-intensity home-based exercise was significantly less effective than high-intensity home-based exercise and was not significantly different from the nonexercise control for improving 6-minute walk distance. These results do not support the use of low-intensity home-based walking exercise for improving objectively measured walking performance in patients with PAD.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02538900.

The renin-angiotensin-aldosterone system blockade and arterial stiffness in renal transplant recipients - a cross-sectional prospective observational clinical study

INTRODUCTION

Arterial stiffness parameters can be used as a predictor of cardiovascular events in the general population and renal transplant recipients (RTRs). Additionally, the renin-angiotensin-aldosterone-system (RAAS) blockade mitigates arterial stiffness in the general population. There are no sufficient data concerning the role of the RAAS blockade in reducing arterial stiffness among patients after kidney transplantation. The aim of this study is to assess the influence of the above blockade on arterial stiffness in RTRs.

METHODS

344 stable RTRs were enrolled in the study. 204 (59.3%) of them received RAAS blockers (angiotensin convertase inhibitors - ACEIs or angiotensin receptor blockers - ARBs): group RAAS (+), and 140 (40.7%) were not treated with such agents: group RAAS (-).

RESULTS

In the RAAS (+) group, 55.9% of the patients used ARBs and 44.1% ACEIs. Cardiovascular disease (coronary artery disease and/or peripheral obliterans artery disease) (27.9% vs 14.3%, p<0.05), and heart failure (27.4% vs 24.3%, p<0.05) were significantly more often diagnosed in the RAAS (+) group when compared to the RAAS (-) group. Systolic blood pressure, diastolic blood pressure and all arterial stiffness parameters (baPWV, cfPWV, pulse pressure) did not differ significantly between the RAAS (+) and RAAS (-) groups. The results revealed that cardiovascular disease in patients was associated with a significant increase in both, the PWV and pulse pressure. No difference between the arterial stiffness parameters was observed in patients with a cardiovascular disease, diabetes and heart failure in the RAAS (+) and RAAS (-) groups. Moreover, beta-blockers and diuretics ameliorated the arterial stiffness parameters.

CONCLUSIONS

This study showed the indication bias of the RAAS prescription, and no conclusion on the influence of RAAS on arterial stiffness can be drawn. The results indicated diuretics and beta-blockers as agents lowering the arterial stiffness in RTRs.

Comparison of Long Term Outcomes After Endovascular Treatment Versus Bypass Surgery in Chronic Limb Threatening Ischaemia Patients with Long Femoropopliteal Lesions

OBJECTIVE

There are currently two treatments available for patients with chronic limb threatening ischaemia (CLTI): open surgical bypass (OSB) and percutaneous transluminal angioplasty with/without stenting (PTA/S). The aim of this study was to compare short and long term outcomes between PTA/S and OSB in CLTI patients with long (GLASS grade III and IV) femoropopliteal disease.

METHODS

This was a two centre retrospective study including all consecutive patients with CLTI undergoing first time lower extremity intervention at two distinct vascular surgical centres. Between 1 January 2012 and 1 January 2018, 1 545 CLTI consecutive limbs were treated for femoropopliteal GLASS grade III and IV lesions at two vascular surgical centres. Using covariables from baseline and angiographic characteristics, a propensity score was calculated for each limb. Thus, comparable patient cohorts (235 in PTA/S and 235 in OSB group) were identified for further analysis. The primary outcomes were freedom from re-intervention in the treated extremity and major amputation. Secondary outcomes were all hospital complications among the two patient groups.

RESULTS

Total overall complication rates were significantly higher in the OSB group (20.42% vs. 5.96%, p < .001), especially wound infection/seroma rate that required prolonged hospitalisation and further treatment (7.65% vs. 0%, p < .001). After the median follow up of 61 months, re-intervention rates were significantly higher in the PTA/S group (log rank test, 44.68% vs. 29.79%, p = .002), but there was no significant difference in terms of major amputation rates between the two group of patients (log rank test, PTA/S 27.23% vs. OSB 22.13%, p = .17).

CONCLUSION

Bypass surgery seems to be superior to PTA/S for GLASS grade III and IV femoropopliteal lesions in patients with CLTI in terms of long term re-intervention rates, but with considerably higher rates of post-operative complications. A larger cohort of patients in currently ongoing randomised trials, as well as prospective cohort studies are necessary to confirm these findings.

High ankle brachial index predicts high risk of cardiovascular events amongst people with peripheral artery disease

Ankle-brachial pressure index (ABPI) is commonly measured in people referred to vascular specialists. This study aimed to assess the association of high ABPI (≥ 1.4) with cardiovascular events in people with peripheral artery disease (PAD). 1533 participants with PAD diagnosed by a vascular specialist were prospectively recruited from four out-patient clinics in Australia. ABPI was measured at recruitment and the occurrence of myocardial infarction (MI), stroke or cardiovascular death (major cardiovascular events; MACE) and any amputation were recorded over a median (inter-quartile range) follow-up of 3.3 (1.0-7.1) years. The association of high, compared to normal, low (0.5-0.9) or very low (<0.5), ABPI with clinical events was estimated using Cox proportional hazard analyses, adjusting for traditional risk factors and reported as hazard ratio with 95% confidence intervals. 596 (38.9%), 676 (44.1%), 157 (10.2%) and 104 (6.8%) participants had normal, low, very low and high ABPI, respectively. Participants with high ABPI had increased risk of MACE, MI and death by comparison to those with either normal ABPI [1.69 (1.07, 2.65), 1.93 (1.07, 3.46) and 1.67 (1.09, 2.56)] or either low or very low ABPI [1.51 (1.02, 2.23), 1.92 (1.16, 3.19) and 1.47 (1.02, 2.14)] after adjusting for other risk factors. Findings were similar in a sensitivity analysis excluding people with ABPI only measured in one leg (n = 120). Participants with high ABPI also had an increased risk of MACE and MI compared to those with very low ABPI alone. High ABPI is a strong indicator of excess risk of cardiovascular events amongst people with PAD.

Effects of external counter-pulsation on endothelial function assessed by peripheral artery tonometry, levels of glycaemia and metabolic markers in individuals with type 2 diabetes mellitus

BACKGROUND AND AIMS

External counter-pulsation (ECP) generates sheer stress thereby improving endothelial function and anginal symptoms in coronary artery disease. Endothelial dysfunction is also involved in the pathogenesis of T2DM. The aim of this pilot study was to investigate the use of ECP at different doses in improving endothelial function and glycaemic markers in T2DM.

METHODS

This prospective study involved 46 subjects with T2DM randomly assigned to receive 35 sessions of ECP at different regimens (0.5 h versus 1 h) and duration (7 versus 12 weeks). Endothelial function was evaluated by reactive hyperaemia index (RHI) via peripheral arterial tonometry at the start, midpoint and end of study. Other secondary outcomes included fasting glucose, HOMA-IR, HbA1c, blood pressure, lipid profile, weight and vibration sense.

RESULTS

There was no change in RHI across all 3 regimens of ECP individually or collectively at the end of the study (ΔRHI +0.01%, p = 0.458). Glycaemic markers also remained unchanged at endpoint. Subgroup analysis showed an improvement in RHI (ΔRHI +20.6%, p = 0.0178) in subjects with more severe endothelial dysfunction at baseline.

CONCLUSION

ECP did not show a beneficial effect on endothelial function or glycemic control in this South-East Asian population with T2DM at any of the three regimens. This may partly be explained by less severe endothelial dysfunction and less insulin resistance in our population at baseline.

Pathology and Multimodality Imaging of Acute and Chronic Femoral Stenting in Humans

OBJECTIVES

The objective of this study was to comprehensively evaluate the pathology of acute and chronic femoral stenting in symptomatic atherosclerotic patients and to understand the causes of stent failure (SF) using multimodality imaging including micro-computed tomography.

BACKGROUND

Although the pathology of coronary stenting has been well studied, the pathology of lower extremity femoral stenting remains poorly understood.

METHODS

Twelve stented femoral lesions removed at surgery (n = 10) and at autopsy (n = 2) were obtained from 10 patients (median age 74 years; interquartile range [IQR]: 66 to 82 years) with histories of peripheral artery disease (critical limb ischemia in 7) (7 men and 3 women). All specimens underwent radiography, micro-computed tomography, and histological assessment.

RESULTS

The median duration of implantation was 150 days (IQR: 30 to 365 days), the median stent diameter was 5.90 mm (IQR: 5.44 to 7.16 mm), and the median stent length was 39.5 mm (IQR: 27 to 107.5 mm). Of the 12 stented lesions, 2 had drug-eluting stents, and 10 had bare-metal stents. SF was observed in 8 of 12 lesions. The major cause of SF was acute thrombosis (6 of 8), but causes varied (delayed healing, stent underexpansion, false lumen stenting, and fracture), and 2 had restenosis. Stent fractures were observed in 3 cases by micro-computed tomography. Both drug-eluting stents, implanted for >1 year, showed delayed healing with circumferential peristrut fibrin deposition and SF.

CONCLUSIONS

This histological study is the first to examine the pathological cause of SF. Stent thrombosis was the major cause of SF. Delayed healing was a common feature of bare-metal stents implanted for <90 days, while all drug-eluting stents, despite implantation duration >1 year, showed delayed healing.

Injectable thermosensitive chitosan-based hydrogel containing ferulic acid for treating peripheral arterial disease

Peripheral arterial disease (PAD) affects more than 200 million people worldwide. Recent studies suggest that oxidative stress-related inflammation can lead to the initiation and progression of PAD. Ferulic acid (FA) is a natural phenolic compound and has been proven to have antioxidant and angiogenesis effects. In this study, thermosensitive chitosan-gelatin-based hydrogel was used as a delivery vehicle of FA. The effects of hydrogel encapsulating FA (FA-gel) have been demonstrated in vitro and in vivo. The results revealed that the developed hydrogel with porous structure could provide a sustained release of FA. Post-treatment of FA-gel effectively decreased the oxidative stress-induced damage in human umbilical vein endothelial cells via decreasing endogenous reactive oxygen species production, inflammation-related gene expression and apoptosis level. In the mouse hindlimb ischemia model, the results revealed that FA-gel could improve blood flow, muscle regeneration and decreases inflammation in veins. These results suggested that FA-gel may have a therapeutic potential in PAD.

Effect of intramuscular baculovirus encoding mutant hypoxia-inducible factor 1-alpha on neovasculogenesis and ischemic muscle protection in rabbits with peripheral arterial disease

BACKGROUND AIMS

Peripheral arterial disease (PAD) is a progressive, disabling ailment for which no effective treatment exists. Gene therapy-mediated neovascularization has emerged as a potentially useful strategy. We tested the angiogenic and arteriogenic efficacy and safety of a baculovirus (BV) encoding mutant, oxygen-resistant hypoxia-inducible factor 1-alpha (mHIF-1α), in rabbits with PAD.

METHODS

After assessing the transfection efficiency of the BV.mHIF-1α vector and its tubulogenesis potential in vitro, we randomized rabbits with experimental PAD to receive 1 × 10⁹ copies of BV.mHIF-1α or BV.null (n = 6 per group) 7 days after surgery. Two weeks post-treatment, collateralization (digital angiography) and capillary and arteriolar densities (immunohistochemistry) were measured in the posterior limbs. Ischemic damage was evaluated in adductor and gastrocnemius muscle samples. Tracking of viral DNA in injected zones and remote tissues at different time points was performed in additional rabbits using a BV encoding GFP.

RESULTS

Angiographically visible collaterals were more numerous in BV.mHIF-1α-treated rabbits (8.12 ± 0.42 vs 6.13 ± 1.15 collaterals/cm², P < 0.05). The same occurred with arteriolar (27.9 ± 7.0 vs 15.3 ± 4.0 arterioles/mm²) and capillary (341.8 ± 109.9 vs 208.8 ± 87.7 capillaries/mm², P < 0.05) densities. BV.mHIF-1α-treated rabbits displayed less ischemic muscle damage than BV.null-treated animals. Viral DNA and GFP mRNA were detectable only at 3 and 7 days after injection in hind limbs. Neither the virus nor GFP mRNA was detected in remote tissues.

CONCLUSIONS

In rabbits with PAD, BV.mHIF-1α induced neovascularization and reduced ischemic damage, exhibiting a good safety profile at 14 days post-treatment. Complementary studies to evaluate its potential usefulness in the clinic are needed.

Intimal and medial calcification in relation to cardiovascular risk factors

Purpose

To assess specific risk factors and biomarkers associated with intimal arterial calcification (IAC) and medial arterial calcification (MAC).

Methods

We conducted a cross-sectional study in patients with or at risk of vascular disease from the SMART study(n = 520) and the DCS cohort(n = 198). Non-contrast computed tomography scanning of the lower extremities was performed and calcification in the femoral and crural arteries was scored as absent, predominant IAC, predominant MAC or indistinguishable. Multinomial regression models were used to assess the associations between cardiovascular risk factors and calcification patterns. Biomarkers for inflammation, calcification and vitamin K status were measured in a subset of patients with IAC(n = 151) and MAC(n = 151).

Results

Femoral calcification was found in 77% of the participants, of whom 38% had IAC, 28% had MAC and 11% were scored as indistinguishable. The absolute agreement between the femoral and crural arteries was high(69%). Higher age, male sex, statin use and history of coronary artery disease were associated with higher prevalences of femoral IAC and MAC compared to absence of calcification. Smoking and low ankle-brachial-index (ABI) were associated with higher prevalence of IAC and high ABI was associated with less IAC. Compared to patients with IAC, patients with MAC more often had diabetes, have a high ABI and were less often smokers. Inactive Matrix-Gla Protein was associated with increased MAC prevalence, while osteonectin was associated with decreased risk of MAC, compared to IAC.

Conclusions

When femoral calcification is present, the majority of the patients have IAC or MAC throughout the lower extremity, which have different associated risk factor profiles.

Correlations of Calf Muscle Macrophage Content With Muscle Properties and Walking Performance in Peripheral Artery Disease

Background Peripheral artery disease (PAD) is a manifestation of atherosclerosis characterized by reduced blood flow to the lower extremities and mobility loss. Preliminary evidence suggests PAD damages skeletal muscle, resulting in muscle impairments that contribute to functional decline. We sought to determine whether PAD is associated with an altered macrophage profile in gastrocnemius muscles and whether muscle macrophage populations are associated with impaired muscle phenotype and walking performance in patients with PAD. Methods and Results Macrophages, satellite cells, and extracellular matrix in gastrocnemius muscles from 25 patients with PAD and 7 patients without PAD were quantified using immunohistochemistry. Among patients with PAD, both the absolute number and percentage of cluster of differentiation (CD) 11b+CD206+ M2-like macrophages positively correlated to satellite cell number (r=0.461 [P=0.023] and r=0.416 [P=0.042], respectively) but not capillary density or extracellular matrix. The number of CD11b+CD206- macrophages negatively correlated to 4-meter walk tests at normal (r=-0.447, P=0.036) and fast pace (r=-0.510, P=0.014). Extracellular matrix occupied more muscle area in PAD compared with non-PAD (8.72±2.19% versus 5.30±1.03%, P<0.001) and positively correlated with capillary density (r=0.656, P<0.001). Conclusions Among people with PAD, higher CD206+ M2-like macrophage abundance was associated with greater satellite cell numbers and muscle fiber size. Lower CD206- macrophage abundance was associated with better walking performance. Further study is needed to determine whether CD206+ macrophages are associated with ongoing reparative processes enabling skeletal muscle adaptation to damage with PAD. Registration URL: https://www.clini​caltr​ials.gov; Unique identifiers: NCT00693940, NCT01408901, NCT0224660.

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.

Development of a two-stage limb ischemia model to better simulate human peripheral artery disease

Peripheral arterial disease (PAD) develops due to the narrowing or blockage of arteries supplying blood to the lower limbs. Surgical and endovascular interventions are the main treatments for advanced PAD but alternative and adjunctive medical therapies are needed. Currently the main preclinical experimental model employed in PAD research is based on induction of acute hind limb ischemia (HLI) by a 1-stage procedure. Since there are concerns regarding the ability to translate findings from this animal model to patients, we aimed to develop a novel clinically relevant animal model of PAD. HLI was induced in male Apolipoprotein E (ApoE-/-) deficient mice by a 2-stage procedure of initial gradual femoral artery occlusion by ameroid constrictors for 14 days and subsequent excision of the femoral artery. This 2-stage HLI model was compared to the classical 1-stage HLI model and sham controls. Ischemia severity was assessed using Laser Doppler Perfusion Imaging (LDPI). Ambulatory ability was assessed using an open field test, a treadmill test and using established scoring scales. Molecular markers of angiogenesis and shear stress were assessed within gastrocnemius muscle tissue samples using quantitative polymerase chain reaction. HLI was more severe in mice receiving the 2-stage compared to the 1-stage ischemia induction procedure as assessed by LDPI (p = 0.014), and reflected in a higher ischemic score (p = 0.004) and lower average distance travelled on a treadmill test (p = 0.045). Mice undergoing the 2-stage HLI also had lower expression of angiogenesis markers (vascular endothelial growth factor, p = 0.004; vascular endothelial growth factor- receptor 2, p = 0.008) and shear stress response mechano-transducer transient receptor potential vanilloid 4 (p = 0.041) within gastrocnemius muscle samples, compared to animals having the 1-stage HLI procedure. Mice subjected to the 2-stage HLI receiving an exercise program showed significantly greater improvement in their ambulatory ability on a treadmill test than a sedentary control group. This study describes a novel model of HLI which leads to more severe and sustained ischemia than the conventionally used model. Exercise therapy, which has established efficacy in PAD patients, was also effective in this new model. This new model maybe useful in the evaluation of potential novel PAD therapies.

Low-density lipoprotein cholesterol goal attainment rates in high-risk patients with cardiovascular diseases and diabetes mellitus in Korea: a retrospective cohort study

BACKGROUND

Real-world evidence of low-density lipoprotein cholesterol (LDL-C) goal attainment rates for Asian patients is deficient. The objective of this study was to assess the status of dyslipidemia management, especially in high-risk patients with cardiovascular disease (CVD) including stroke and acute coronary syndrome (ACS).

METHODS

This was a retrospective cohort study of 514,866 subjects from the National Health Insurance Service-National Health Screening Cohort database in Korea. Participants were followed up from 2002 to 2015. Subjects with a high-risk of CVD prior to LDL-C measurement and subjects who were newly-diagnosed for high-risk of CVD following LDL-C measurement were defined as known high-risk patients (n = 224,837) and newly defined high-risk patients (n = 127,559), respectively. Data were analyzed by disease status: stroke, ACS, coronary heart disease (CHD), peripheral artery disease (PAD), diabetes mellitus (DM) and atherosclerotic artery disease (AAD).

RESULTS

Overall, less than 50% of patients in each disease category achieved LDL-C goals (LDL-C < 70 mg/dL in patients with stroke, ACS, CHD and PAD; and LDL-C < 100 mg/dL in patients with DM and AAD). Statin use was observed in relatively low proportions of subjects (21.5% [known high-risk], 34.4% [newly defined high-risk]). LDL-C goal attainment from 2009 to 2015 steadily increased but the goal-achiever proportion of newly defined high-risk patients with ACS remained reasonably constant (38.7% in 2009; 38.1% in 2015).

CONCLUSIONS

LDL-C goal attainment rates in high-risk patients with CVD and DM in Korea demonstrate unmet medical needs. Proactive management is necessary to bridge the gap between the recommendations of clinical guidelines and actual clinical practice.

Histological features of restenosis associated with paclitaxel drug-coated balloon: implications for therapy

PURPOSE

To investigate the cellular and extracellular changes induced by drug-coated balloons (DCB) in the treatment of superficial femoral artery (SFA) restenosis, and to compare histopathological features with those observed after plain old balloon angioplasty (POBA) from the same patients.

METHODS AND RESULTS

Plaque samples for five patients with SFA restenosis (first-time) after POBA were collected using atherectomy and DCB. These samples constitute the POBA restenosis group. The same five patients developed recurrent restenosis (RR) after DCB, at the same intervention site. These SFA-RR lesions were again treated using atherectomy and POBA. These samples constitute the DCB restenosis group. DCB restenosis group plaques showed significant reduction in neointima, smooth muscle cells, fibroblast densities, and Ki67 index; and increase in caspase 3, features of apoptosis and type III collagen deposition in comparison to the POBA restenosis group.

CONCLUSION

Plaque tissue from the DCB restenosis group show reductions in neointimal thickness, cellularity, and cellular proliferation, along with increased apoptosis, and Type III collagen content. These results suggest a different mechanistic pathway for DCB restenosis, in which neointimal proliferation is reduced but reparative fibrosis is increased. The treatment for SFA-RR after DCB may therefore benefit from different forms of therapy including scaffolding, rather than recurrent anti-proliferative therapy.

HbA1c predicts long-term postoperative mortality in patients with unknown glycemic status at admission for vascular surgery: An exploratory study

BACKGROUND

Peripheral arterial disease (PAD) and diabetes mellitus (DM) represent major public health challenges and are tightly associated. To facilitate early diagnosis, HbA1c has been implemented as the preferred diagnostic tool for the diagnosis of type 2 DM. In this study, we compared and evaluated HbA1c, fasting plasma glucose (FPG), and 2-hour post-load glucose values to determine which test best predicted mortality in patients with PAD.

METHODS

In all, 273 PAD patients with unknown glycemic status admitted to Haukeland University Hospital for elective surgery between October 2006 and September 2007 were included in the study. All 273 patients underwent a standard oral glucose tolerance test (OGTT) in addition to determination of HbA1c; patients were then grouped into those with DM, intermediate hyperglycemia, and normoglycemia according to World Health Organization and International Expert Committee criteria.

RESULTS

All-cause mortality was 40% over a 9-year follow-up period. After adjusting for age, sex, and relevant medication, HbA1c was a predictor for mortality (hazard ratio [HR] 1.54; 95% confidence interval [CI] 1.03-2.32]; P = 0.04). The association did not achieve statistical significance in a fully adjusted Cox regression model, although the effect estimation of HbA1c on all-cause mortality remained largely unchanged (HR 1.39; 95% CI 0.92-2.09; P = 0.13). The OGTT was not a predictor of long-term mortality.

CONCLUSIONS

The results indicate that HbA1c is a useful marker in the preoperative screening of patients of unknown glycemic status at the time of admission for vascular surgery, and may identify people at high risk of long-term mortality following surgical treatment for PAD.

Mechanical damage characterization in human femoropopliteal arteries of different ages

Endovascular treatment of Peripheral Arterial Disease (PAD) is notorious for high failure rates, and interaction between the arterial wall and the repair devices plays a significant role. Computational modeling can help improve clinical outcomes of these interventions, but it requires accurate inputs of elastic and damage characteristics of the femoropopliteal artery (FPA) which are currently not available. Fresh human FPAs from n = 104 tissue donors 14-80 years old were tested using planar biaxial extension to capture elastic and damage characteristics. Damage initiation stretches and stresses were determined for both longitudinal and circumferential directions, and their correlations with age and risk factors were assessed. Two and four-fiber-family invariant-based constitutive models augmented with damage functions were used to describe stress softening with accumulating damage. In FPAs younger than 50 years, damage began accumulating after 1.51 ± 0.13 and 1.49 ± 0.11 stretch, or 196 ± 110 kPa and 239 ± 79 kPa Cauchy stress in the longitudinal and circumferential directions, respectively. In FPAs older than 50 years, damage initiation stretches and stresses decreased to 1.27 ± 0.09 (106 ± 52 kPa) and 1.26 ± 0.09 (104 ± 59 kPa), respectively. Damage manifested primarily as tears at the internal and external elastic laminae and within the tunica media layer. Higher body mass index and presence of diabetes were associated with lower damage initiation stretches and higher stresses. The selected constitutive models were able to accurately portray the FPA behavior in both elastic and inelastic domains, and properties were derived for six age groups. Presented data can help improve fidelity of computational models simulating endovascular PAD repairs that involve arterial damage. STATEMENT OF SIGNIFICANCE: This manuscript describes inelastic, i.e. damage, behavior of human femoropopliteal arteries, and provides values for three constitutive models simulating this behavior computationally. Using a set of 104 human FPAs 14-80 years old, we have investigated stress and stretch levels corresponding to damage initiation, and have studied how these damage characteristics change across different age groups. Presented inelastic arterial characteristics are important for computational simulations modeling balloon angioplasty and stenting of peripheral arterial disease lesions.

Association of Survival With Femoropopliteal Artery Revascularization With Drug-Coated Devices

Importance

In a recent meta-analysis of randomized clinical trials, femoropopliteal artery revascularization with paclitaxel drug-coated devices was associated with increased long-term all-cause mortality compared with non-drug-coated devices. However, to our knowledge, these findings have not been replicated in other data sources and may be subject to confounding from missing data associated with patient withdrawal and loss to follow-up.

Objective

To evaluate differences in all-cause mortality between patients who were treated with drug-coated devices vs non-drug-coated devices for femoropopliteal artery revascularization.

Design, Setting, and Participants

This nationwide, multicenter retrospective cohort study included 16 560 Centers for Medicare and Medicaid Services beneficiaries who were admitted for femoropopliteal artery revascularization from January 1, 2016, to December 31, 2016. All-cause mortality was analyzed through September 30, 2017.

Exposures

Drug-coated devices (drug-eluting stent [DES] or drug-coated balloon [DCB]) compared with non-drug-coated devices (bare metal stent or uncoated percutaneous transluminal angioplasty balloon).

Main Outcomes and Measures

The primary outcome was all-cause mortality analyzed through the end of follow-up.

Results

Among 16 560 patients treated at 1883 hospitals, the mean (SD) age was 72.9 (11) years, 7734 (46.7%) were men, 12 232 (73.9%) were white, 8222 (49.7%) currently or had previously used tobacco, 9817 (59.3%) had diabetes, and 8450 (51.0%) had critical limb ischemia (CLI). Drug-coated devices were used in 5989 participants (36.2%). The median follow-up was 389 days (interquartile range, 277-508 days). Among all patients, treatment with drug-coated devices was associated with a lower cumulative incidence of all-cause mortality compared with treatment with non-drug-coated devices through 600 days postprocedure (32.5% vs 34.3%, respectively; log-rank P = .007). Similar survival trends were observed when treatment was stratified by using a DCB alone or DES with or without DCB. After multivariable adjustment, drug-coated devices were not associated with a difference in all-cause mortality compared with non-drug-coated devices (hazard ratio [HR], 0.97; 95% CI, 0.91-1.04; P = .43). These findings were consistent among those with CLI (HR, 0.93; 95% CI, 0.85-1.01; P = .09) or without CLI (HR, 0.94; 95% CI, 0.85-1.03; P = .20), and for those treated with DCB alone (HR, 0.94; 95% CI, 0.86-1.03; P = .17) or DES with or without DCB (HR, 0.97; 95% CI, 0.89-1.06; P = .48).

Conclusions and Relevance

In this large nationwide analysis of Centers for Medicare and Medicaid Services beneficiaries, there was no evidence of increased all-cause mortality following femoropopliteal artery revascularization with drug-coated devices compared with non-drug-coated devices.

Comparison between paclitaxel-coated balloon and standard uncoated balloon in the treatment of femoropopliteal long lesions in diabetics

Atherosclerotic diseases may include femoropopliteal artery stenosis or occlusion. Percutaneous transluminal angioplasty (PTA) is an effective and minimally invasive treatment strategy for atherosclerotic femoropopliteal artery stenosis/occlusion disease. Balloon angioplasty is a widely used technique in the management of occlusive disease in almost all arterial segments.We enrolled 111 diabetics with long femoropopliteal lesions, among which 54 received PTA with paclitaxel-coated balloon (the Paclitaxel group), and 57 with standard balloon catheters (the Control group).The primary outcome was set as angiographic late lumen loss (LLL) within 6 months; the secondary angiographic outcome was binary restenosis. Clinical outcomes included Rutherford clarification, ankle-brachial index (ABI) and rate of clinically driven target lesion revascularization (TLR). Two groups had similar basal clinical features, angiographic and procedural characteristics. Compared to controls, the Paclitaxel group had a significantly lower 6-month LLL rate, 12-month binary restenosis rate, 12-month TLR, lower Rutherford grades at 3 and 6 months, and higher ABI at 3 months. For all factors which might influence outcomes, fasting blood glucose was negatively correlated with ABI; the blood urea nitrogen (BUN) was positively related with the Rutherford clarification grades. In addition, the coronary heart disease (CHD) and smoking histories were positively correlated with residual stenosis after treatment.Collectively, the paclitaxel-coated balloon angioplasty can yield more favorable angiographic and clinical outcomes than standard uncoated balloon angioplasty, even in the more challenging lesions (the long and occlusive femoropopliteal lesions) in diabetics, when it had a similar safety profile to the traditional balloon. Blood glucose, BUN, CHD, and smoking imply poor curative effects.

Protocol for a prospective, longitudinal cohort study on the effect of arterial disease level on the outcomes of supervised exercise in intermittent claudication: the ELECT Registry

INTRODUCTION

Despite guideline recommendations advocating conservative management before invasive treatment in intermittent claudication, early revascularisation remains widespread in patients with favourable anatomy. The aim of the Effect of Disease Level on Outcomes of Supervised Exercise in Intermittent Claudication Registry is to determine the effect of the location of stenosis on the outcomes of supervised exercise in patients with intermittent claudication due to peripheral arterial disease.

METHODS AND ANALYSIS

This multicentre prospective cohort study aims to enrol 320 patients in 10 vascular centres across the Netherlands. All patients diagnosed with intermittent claudication (peripheral arterial disease: Fontaine II/Rutherford 1-3), who are considered candidates for supervised exercise therapy by their own physicians are appropriate to participate. Participants will receive standard care, meaning supervised exercise therapy first, with endovascular or open revascularisation in case of insufficient effect (at the discretion of patient and vascular surgeon). For the primary objectives, patients are grouped according to anatomical characteristics of disease (aortoiliac, femoropopliteal or multilevel disease) as apparent on the preferred imaging modality in the participating centre (either duplex, CT angiography or magnetic resonance angiography). Changes in walking performance (treadmill tests, 6 min walk test) and quality of life (QoL; Vascular QoL Questionnaire-6, WHO QoL Questionnaire-Bref) will be compared between groups, after multivariate adjustment for possible confounders. Freedom from revascularisation and major adverse cardiovascular disease events, and attainment of the treatment goal between anatomical groups will be compared using Kaplan-Meier survival curves.

ETHICS AND DISSEMINATION

This study has been exempted from formal medical ethical approval by the Medical Research Ethics Committees United 'MEC-U' (W17.071). Results are intended for publication in peer-reviewed journals and for presentation to stakeholders nationally and internationally.

TRIAL REGISTRATION NUMBER

NTR7332; Pre-results.

Association between carotid artery stenosis and peripheral artery disease: Evaluation by screening carotid ultrasonography (cross-sectional study)

We aimed to investigate the association between carotid artery stenosis and peripheral artery disease (PAD) by screening carotid ultrasonography (CUS).From January 2012 to December 2015, 231 consecutive patients who had undergone preoperative CUS for PAD were included in this study. A radiologist assessed the degree of internal carotid artery (ICA) stenosis by using the North American Symptomatic Carotid Endarterectomy Trial (NASCET). Severe (>70%) ICA stenosis was evaluated based on the type of vascular surgery, PAD lesion, and ankle-brachial index (ABI). Data were analyzed using multiple logistic regression analysis and the χ test.Among 231 PAD patients, multilevel lesions revealed significantly higher incidence of severe ICA stenosis than iliac and infrainguinal lesion (22.5% vs 9.4% vs 8%: P = .016). Age (odds ratio [OR]: 1.05, 95% confidence interval [CI]: 1.00-1.12: P = .035), chronic kidney disease (CKD, OR: 6.19, 95% CI: 2.04-45.04: P = .013), and cerebral vascular disease (CVD, OR: 4.08, 95% CI: 1.13-16.46: P = .037) were significant risk factors of severe ICA stenosis in multivariate analysis. Prevalence of severe ICA stenosis according to ABI in PAD was not significant.Preoperative screening by CUS provides valuable information onasymptomatic carotid artery stenosis (ACAS) that can identify severe ACAS patients who are at high risk of stroke and to consider more intensive management of carotid disease in PAD patients. CUS can be a useful noninvasive preoperative screening imaging tool for PAD patients with multilevel lesions, aged > 65 years old, with CKD and CVD.

Rapid inhibition of atherosclerotic plaque progression by sonodynamic therapy

Aims

Currently, efficient regimens to reverse atherosclerotic plaques are not available in the clinic. Herein, we present sonodynamic therapy (SDT) as a novel methodology to rapidly inhibit progression of atherosclerotic plaques.

Methods and results

In atherosclerotic rabbit and apoE-deficient mouse models, SDT efficiently decreased the atherosclerotic burden within 1 week, revealing a decrease in the size of the atherosclerotic plaque and enlarged lumen. The shrunken atherosclerotic plaques displayed compositional alterations, with a reduction in lesional macrophages and lipids. The rapid efficacy of SDT may be due to its induction of macrophage apoptosis, enhancement of efferocytosis, and amelioration of inflammation in the atherosclerotic plaque. Compared with atorvastatin, the standard of care for atherosclerosis, SDT showed more significant plaque shrinkage and lumen enlargement during 1 week treatment. Furthermore, SDT displayed good safety without obvious side effects. In a pilot clinical trial recruiting the patients suffering atherosclerotic peripheral artery disease, combination therapy of SDT with atorvastatin efficiently reduced progression of atherosclerotic plaque within 4 weeks, and its efficacy was able to last for at least 40 weeks.

Conclusion

SDT is a non-invasive and efficacious regimen to inhibit atherosclerotic plaque progression.

A polymer-coated, paclitaxel-eluting stent (Eluvia) versus a polymer-free, paclitaxel-coated stent (Zilver PTX) for endovascular femoropopliteal intervention (IMPERIAL): a randomised, non-inferiority trial

BACKGROUND

The clinical effect of a drug-eluting stent in the femoropopliteal segment has not been investigated in a randomised trial with a contemporary comparator. The IMPERIAL study sought to compare the safety and efficacy of the polymer-coated, paclitaxel-eluting Eluvia stent with the polymer-free, paclitaxel-coated Zilver PTX stent for treatment of femoropopliteal artery segment lesions.

METHODS

In this randomised, single-blind, non-inferiority study, patients with symptomatic lower-limb ischaemia manifesting as claudication (Rutherford category 2, 3, or 4) with atherosclerotic lesions in the native superficial femoral artery or proximal popliteal artery were enrolled at 65 centres in Austria, Belgium, Canada, Germany, Japan, New Zealand, and the USA. Patients were randomly assigned (2:1) with a site-specific, web-based randomisation schedule to receive treatment with Eluvia or Zilver PTX. All patients, site personnel, and investigators were masked to treatment assignment until all patients had completed 12 months of follow-up. The primary efficacy endpoint was primary patency (defined as a peak systolic velocity ratio ≤2·4, without clinically driven target lesion revascularisation or bypass of the target lesion) and the primary safety endpoint was major adverse events (ie, all causes of death through 1 month, major amputation of target limb through 12 months, and target lesion revascularisation through 12 months). We set a non-inferiority margin of -10% at 12 months. Primary non-inferiority analyses were done when the minimum sample size required for adequate statistical power had completed 12 months of follow-up. The primary safety non-inferiority analysis included all patients who had completed 12 months of follow-up or had a major adverse event through 12 months. This trial is registered with ClinicalTrials.gov, number NCT02574481.

FINDINGS

Between Dec 2, 2015, and Feb 15, 2017, 465 patients were randomly assigned to Eluvia (n=309) or to Zilver PTX (n=156). Non-inferiority was shown for both efficacy and safety endpoints at 12 months: primary patency was 86·8% (231/266) in the Eluvia group and 81·5% (106/130) in the Zilver PTX group (difference 5·3% [one-sided lower bound of 95% CI -0·66]; p<0·0001). 259 (94·9%) of 273 patients in the Eluvia group and 121 (91·0%) of 133 patients in the Zilver PTX group had not had a major adverse event at 12 months (difference 3·9% [one-sided lower bound of 95% CI -0·46]; p<0.0001). No deaths were reported in either group. One patient in the Eluvia group had a major amputation and 13 patients in each group required target lesion revascularisation.

INTERPRETATION

The Eluvia stent was non-inferior to the Zilver PTX stent in terms of primary patency and major adverse events at 12 months after treatment of patients for femoropopliteal peripheral artery disease.

FUNDING

Boston Scientific.

Media sclerosis drives and localizes atherosclerosis in peripheral arteries

Media sclerosis (MS) and peripheral artery disease (PAD) may coincide, particularly in type 2 diabetics (T2D) and in patients with chronic kidney disease (CKD). In contrast to non-diabetics, in T2D PAD is more severe and more distal. Although MS is suspected to play a role, the underlying pathophysiological reasons for the differences still remain elusive today. We tested the hypothesis that MS is a promoter of atherosclerosis as it occurs in T2D with PAD by interfering with arterial remodeling using an in-silico simulation. We confirmed that MS aggravates PAD by promoting negative remodeling. We found that the effect is more pronounced in smaller distal arteries compared to larger proximal ones. Our results suggest that the degree of this divergence depends on the ratio between the thickness of the intima relative to the thickness of the media/adventitia of the individually affected arteries.

Assessment of longitudinal distribution of subclinical atherosclerosis in femoral arteries by three-dimensional cardiovascular magnetic resonance vessel wall imaging

BACKGROUND

Lower extremity peripheral artery disease has become a significant health burden worldwide. Since the treatment strategies can be different if atherosclerotic disease involves different femoral artery segments, it is important to assess plaque distribution among different segments of femoral arteries. We sought to investigate the longitudinal distribution of subclinical femoral artery atherosclerosis in asymptomatic elderly adults using cardiovascular magnetic resonance (CMR) vessel wall imaging.

METHODS

Asymptomatic elderly subjects underwent three-dimensional (3D) CMR vessel wall imaging for femoral arteries. The 3D motion sensitized-driven equilibrium prepared rapid gradient-echo (3D-MERGE) sequence was acquired from the common femoral artery to the popliteal artery. The femoral artery was divided into 4 segments: common femoral artery (CFA), proximal superficial femoral artery (pSFA), adductor canal (AC) segment of femoral artery, and popliteal artery (PA). The morphological characteristics including lumen area, wall area, maximum and minimum wall thickness, normalized wall index (NWI = wall area / [lumen area + wall area] × 100%), and eccentricity index ([maximum wall thickness - minimum wall thickness] / maximum wall thickness), luminal stenosis, and presence of atherosclerotic plaque were evaluated and compared between bilateral sides and among different femoral artery segments in each side of femoral artery. The associations between ankle-brachial index (ABI) and cardiovascular risk factors and femoral artery plaque characteristics were also determined.

RESULTS

Of 107 recruited subjects (71.9 ± 5.6 years; 48 males), 70 (65.4%) were found to have femoral artery plaques. The atherosclerotic plaques were most frequently found in PA (41.1%) and CFA (40.2%) segments, followed by pSFA (31.8%) and AC (23.4%) segments (p = 0.002). Similarly, PA and CFA segments showed significantly greater maximum wall thickness and eccentricity index compared with pSFA and AC segments (all p < 0.001). Significant differences can be found in NWI among four segments of femoral arteries (p < 0.001) and PA showed the highest NWI (54.8%), followed by AC (54.3%), pSFA (52.4%) and CFA (45.9%) segments. Compared with right femoral artery, left femoral artery had significant smaller lumen area and greater NWI in most of segments (p < 0.002). There were no significant differences in ABI between subjects with and without atherosclerotic plaques (p = 0.161). The presence of subclinical atherosclerotic plaque in femoral arteries was significantly associated with cardiovascular risk factors including age (odds ratio [OR], 1.133; 95% confidence interval [CI], 1.048-1.224, p = 0.002), male gender (OR, 3.914; 95% CI, 1.612-9.501, p = 0.003), and hypertension (OR, 4.000; 95% CI, 1.700-9.411, p = 0.001), respectively.

CONCLUSIONS

Subclinical femoral artery atherosclerosis is prevalent in the elderly population, particularly in the left femoral artery and segments of CFA and PA, and is associated with age, male gender and hypertension. Our findings suggest that, for screening subclinical atherosclerosis, more attention needs to be paid to the specific side and segments of femoral arteries, particularly older individuals and those with these cardiovascular disease risk factors.

Pathology of Peripheral Artery Disease in Patients With Critical Limb Ischemia

BACKGROUND

Critical limb ischemia (CLI) is the most serious complication of peripheral artery disease (PAD).

OBJECTIVES

The purpose of this study was to characterize pathology of PAD in below- and above-knee amputation specimens in patients presenting with CLI.

METHODS

Peripheral arteries from 95 patients (121 amputation specimens) were examined; 75 patients had presented with CLI, and the remaining 20 had amputations performed for other reasons. The pathological characteristics were separately recorded for femoral and popliteal arteries (FEM-POP), and infrapopliteal arteries (INFRA-POP).

RESULTS

A total of 299 arteries were examined. In the 239 arteries from CLI patients, atherosclerotic plaques were more frequent in FEM-POP (23 of 34, 67.6%) compared with INFRA-POP (79 of 205, 38.5%) arteries. Of these 239 arteries, 165 (69%) showed ≥70% stenosis, which was due to significant pathological intimal thickening, fibroatheroma, fibrocalcific lesions, or restenosis in 45 of 165 (27.3%), or was due to luminal thrombi with (39 of 165, 23.6%) or without (81 of 165, 49.1%) significant atherosclerotic lesions. Presence of chronic luminal thrombi was more frequently observed in arteries with insignificant atherosclerosis (OR: 16.7; p = 0.0002), more so in INFRA-POP compared with FEM-POP (OR: 2.14; p = 0.0041) arteries. Acute thrombotic occlusion was less frequently encountered in INFRA-POP than FEM-POP arteries (OR: 0.27; p = 0.0067). Medial calcification was present in 170 of 239 (71.1%) large arteries.

CONCLUSIONS

Thrombotic luminal occlusion associated with insignificant atherosclerosis is commonly observed in CLI and suggests the possibility of atherothromboembolic disease. The pathological characteristics of arteries in CLI suggest possible mechanisms of progression of PAD to CLI, especially in INFRA-POP arteries, and may support the preventive role of antithrombotic agents.

Emerging Role of High Mobility Group Box-1 in Thrombosis-Related Diseases

High mobility group box-1 (HMGB-1), a typical damage-associated molecular pattern protein released from various cells, was first identified in 1973. It is usually stored in the nuclei of cells. Several modifications of HMGB-1 promote its translocation to the cytosol, and it is actively or passively released from cells. When outside of the cells, HMGB-1is crucial in inflammation. It exerts its biological functions via interaction with its receptors, including receptor for advanced glycation end products (RAGE) and Toll-like receptor 4(TLR4). A large number of studies showed a close link between inflammation and thrombosis. This review demonstrated the increased expression of HMGB-1 in thrombosis-related diseases, including coronary artery disease, stroke, peripheral arterial disease, disseminated intravascular coagulation, and venous thrombosis. Besides, it summarized the current understanding of the emerging link between HMGB-1 and thrombosis from three aspects: platelet, NETs, and coagulation and fibrinolysis factors. Finally, it explored the possible therapeutic strategies targeting HMGB-1 for treating thrombosis-related diseases.

Crural Bypass Surgery in Case of Critical Ischemia: Technical Aspects and Results

Background Crural bypass surgery is one of the last options to salvage the leg. Compared to arterial reconstructions of more proximal localization patency rates are generally less good. The aim of this retrospective study was to answer the question if crural bypass surgery is justified. For that we focused on different technicalities, bypass material, recipient vessel and anticoagulation regimes. Objective To know outcome of crural bypass in terms of patency rates, survival rates, amputation. The difference in outcome is compared in different stages of peripheral arterial disease and various bypass materials and sites. Method Between 07/2013 and 06/2018 we performed 102 crural bypasses (27 female, 75 male; age 44-90 (70) years). Reasons for the bypasses were a critical peripheral arterial diseases (PAD) (stage III [pain at rest] and IV [necrosis/gangrene] according to Fontaine). End point of the study was major amputation or death. All patients were operated on in the same department by two experienced vascular surgeons. Result Amputation-free time was 78% after sixmonths and 70% after 24 and 60 months. Six, 12 and 40 months survival was 83%, 78% and 59%, respectively. Patency rates were affected by the severity of the disease (stage III vs. stage IV) and so was major amputation. Autologous bypasses were not associated with a better patency rate. Minor amputation or the anticoagulation scheme did not influence the long term results. Conclusion The long term survival after crural bypass is good and amputation rates are low, independent of the vessel of the lower leg used as recipient outflow. Accordingly, if a bypass is technically feasible, there is no limitation regarding the choice of the recipient vessel. If possible, autologous vein should be used, but a graft prosthesis can lead to equally good results. As patients with stage III PAD have better outcomes, early intervention is recommended in order to avoid deterioration to stage IV.

High-Fat, High-Sugar Diet-Induced Subendothelial Matrix Stiffening is Mitigated by Exercise

Consumption of a high-fat, high-sugar diet and sedentary lifestyle are correlated with bulk arterial stiffening. While measurements of bulk arterial stiffening are used to assess cardiovascular health clinically, they cannot account for changes to the tissue occurring on the cellular scale. The compliance of the subendothelial matrix in the intima mediates vascular permeability, an initiating step in atherosclerosis. High-fat, high-sugar diet consumption and a sedentary lifestyle both cause micro-scale subendothelial matrix stiffening, but the impact of these factors in concert remains unknown. In this study, mice on a high-fat, high-sugar diet were treated with aerobic exercise or returned to a normal diet. We measured bulk arterial stiffness through pulse wave velocity and subendothelial matrix stiffness ex vivo through atomic force microscopy. Our data indicate that while diet reversal mitigates high-fat, high-sugar diet-induced macro- and micro-scale stiffening, exercise only significantly decreases micro-scale stiffness and not macro-scale stiffness, during the time-scale studied. These data underscore the need for both healthy diet and exercise to maintain vascular health. These data also indicate that exercise may serve as a key lifestyle modification to partially reverse the deleterious impacts of high-fat, high-sugar diet consumption, even while macro-scale stiffness indicators do not change.

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.

A Murine Model of Hind Limb Ischemia to Study Angiogenesis and Arteriogenesis

Therapeutic angiogenesis offers promise as a novel treatment that is complementary to surgical or endovascular procedures for peripheral arterial diseases (PAD). Appropriate development and use of hind limb ischemia models is necessary for successful studies of therapeutic angiogenesis and/or arteriogenesis. In this chapter, we describe two commonly used murine unilateral hind limb ischemia models, the femoral artery transection model and the femoral/saphenous artery excision model.

Dietary patterns, plasma vitamins and Trans fatty acids are associated with peripheral artery disease

BACKGROUND

To investigate the association between dietary patterns (DP), plasma vitamins and trans fatty acids (TFAs) with the likelihood of peripheral artery disease (PAD).

METHODS

National Health and Nutrition Examination Survey (NHANES) data for the years 1999-2002 were used. PAD was diagnosed by ankle brachial index assessment. Plasma concentrations of vitamins were measured using high performance liquid chromatography. Vitamin D levels were measured by radioimmunoassay. Analysis of covariance, principal components analysis (PCA) and adjusted logistic regression were applied, accounting for the survey design and sample weights.

RESULTS

Of the 4864 eligible participants, 2482 (51.0%) were men and 269 (5.5%) had prevalent PAD. PCA uncovered three DPs which accounted for 56.8% of the variance in dietary nutrients consumption including DP1 (fatty acids and cholesterol), DP2 (minerals, vitamins and fiber), and DP3 (polyunsaturated fatty acids [PUFA]). PAD patients had a significantly higher serum concentrations of trans 9-octadecenoic acid and trans 9, trans 12-octadienoic acid as well as lower plasma levels of vitamin D, retinol, retinyl stearate and retinyl palmitate (p < 0.001 for all comparisons). In models adjusted for age, race, diabetes, cholesterol, hypertension, smoking and energy intake, individuals in the highest quartile of the DP1 had higher odds for PAD compared with those in the lowest quartile [(odds ratio (OR): 6.43, 95% confidence interval (CI): 2.00-20.63 p < 0.001], while those in the highest quartile of DP2 and DP3 had lower odds of PAD relative to those in the lowest quartile (OR:0.28, OR:0.44, respectively; p < 0.001 for both comparisons).

CONCLUSION

We found that quality of diet, plasma vitamins and TFAs are associated with the likelihood of PAD. If confirmed in prospective studies, the possibility that dietary factors, plasma vitamins and TFAs might be valuable for preventing or delaying the clinical progression of PAD, should be investigated in intervention trials.

Increased Number of Mast Cells in Atherosclerotic Lesions Correlates with the Presence of Myeloid but not Plasmacytoid Dendritic Cells as well as Pro-inflammatory T Cells

BACKGROUND

Atherosclerosis is an inflammatory disease of the vessel wall promoted by different immune cells and inflammatory mediators.

METHODS

In this study, 26 human plaques and 12 control vessels without atherosclerosis were immunohistochemically stained to analyze the emergence of mast cells dependent on plaque morphology and to correlate mast cell occurrence with the emergence of myeloid as well as plasmacytoid dendritic cells. Also, mast cell emergence was correlated with the number of pro-inflammatory T cells. For this, plaques were classified as stable or unstable according to established histological criteria.

RESULTS

As expected, atherosclerotic lesions showed significantly higher numbers of tryptase+, chymase+, and cathepsin G+ mast cells compared to control vessels, particularly in lesions with unstable morphology. As a novel finding, we detected significant correlations between mast cells and myeloid dendritic cells (fascin, CD83, r > 0.3, p < 0.01), but not plasmacytoid dendritic cells (CD123, CD304). Also, we observed significant correlations of mast cells and different subgroups of pro-inflammatory T cells (CD3, CD8, CD161, CD25; r > 0.35, p < 0.05).

CONCLUSIONS

Overall, the higher number of mast cells in plaques, particularly with unstable morphology, suggests that mast cells might be involved in the progression of atherosclerosis. The correlation of mast cells with other immune cells that are pivotal in atherogenesis, e.g., myeloid dendritic cells and pro-inflammatory T cells, also suggests an interplay leading to plaque destabilization. Therefore, modulating local mast cell function and invasion into the plaque might be a therapeutic tool for plaque stabilization.

Analysis of ischemic muscle in patients with peripheral artery disease using X-ray spectroscopy

BACKGROUND

Peripheral artery disease (PAD) is a vascular disease caused by atherosclerosis, resulting in decreased blood flow to the lower extremities. The ankle-brachial index (ABI) is a standard PAD diagnostic test but only identifies reduced blood flow based on blood pressure differences. The early signs of PAD manifest themselves not only at a clinical level but also at an elemental and biochemical level. However, the biochemical and elemental alterations to PAD muscle are not well understood. The objective of this study was to compare fundamental changes in intracellular elemental compositions between control, claudicating, and critical limb ischemia muscle tissue.

MATERIALS AND METHODS

Gastrocnemius biopsies from three subjects including one control (ABI ≥ 0.9), one claudicating (0.4 ≤ ABI < 0.9), and one critical limb ischemia patient (ABI < 0.4) were evaluated using a scanning electron microscope and energy dispersive X-ray spectroscopy to quantify differences in elemental compositions. Spectra were collected for five myofibers per specimen. An analysis of variance was performed to identify significant differences in muscle elemental compositions.

RESULTS

This study revealed that intracellular magnesium and calcium were lower in PAD compared with control myofibers, whereas sulfur was higher. Magnesium and calcium are antagonistic, meaning, if magnesium concentrations go down calcium concentrations should go up. However, our findings do not support this antagonism in PAD. Our analysis found decreases in sodium and potassium, in PAD myofibers.

CONCLUSIONS

These findings may provide insight into the pathologic mechanisms that may operate in ischemic muscle and aid in the development of specialized preventive and rehabilitative treatment plans for PAD patients.

Transpedal Access for the Management of Complex Peripheral Artery Disease

OBJECTIVES

To evaluate the safety and efficacy of transpedal access for the management of complex peripheral artery disease (PAD).

INTRODUCTION

Critical limb ischemia is associated with high risk of limb loss, as well as cardiovascular and all-cause mortality. Transpedal access is a novel, increasingly utilized technique for the management of complex PAD.

METHODS

We performed a literature search using PubMed from January 2003 to December 2016. Published studies on transpedal access were studied. We evaluated patient sample demographics, procedure indications, access and target vessel, procedural characteristics, outcomes, and complications.

RESULTS

Ten studies and 881 patients were included in our study. The indication for transpedal access was critical limb ischemia in 68.4% and severe claudication in 29.5%. A chronic total occlusion was present in 93.7% (average occlusion length, 206 mm). Access was achieved by ultrasound in 57.1% and by fluoroscopy in 35.7%. The anterior tibial or dorsalis pedis were accessed in 54.7% and the posterior tibial in 28.0%. The angiographic procedural success rate was 92.6%. The most commonly reported complication was dissection (7.49%), followed by perforation (1.36%) and embolization (1.25%).

CONCLUSION

Based on the results of this systematic review, transpedal access appears to be a safe and effective technique for complex PAD.

High-resolution and accelerated multi-parametric mapping with automated characterization of vessel disease using intravascular MRI

BACKGROUND

Atherosclerosis is prevalent in cardiovascular disease, but present imaging modalities have limited capabilities for characterizing lesion stage, progression and response to intervention. This study tests whether intravascular magnetic resonance imaging (IVMRI) measures of relaxation times (T1, T2) and proton density (PD) in a clinical 3 Tesla scanner could characterize vessel disease, and evaluates a practical strategy for accelerated quantification.

METHODS

IVMRI was performed in fresh human artery segments and swine vessels in vivo, using fast multi-parametric sequences, 1-2 mm diameter loopless antennae and 200-300 μm resolution. T1, T2 and PD data were used to train a machine learning classifier (support vector machine, SVM) to automatically classify normal vessel, and early or advanced disease, using histology for validation. Disease identification using the SVM was tested with receiver operating characteristic curves. To expedite acquisition of T1, T2 and PD data for vessel characterization, the linear algebraic method ('SLAM') was modified to accommodate the antenna's highly-nonuniform sensitivity, and used to provide average T1, T2 and PD measurements from compartments of normal and pathological tissue segmented from high-resolution images at acceleration factors of R ≤ 18-fold. The results were validated using compartment-average measures derived from the high-resolution scans.

RESULTS

The SVM accurately classified ~80% of samples into the three disease classes. The 'area-under-the-curve' was 0.96 for detecting disease in 248 samples, with T1 providing the best discrimination. SLAM T1, T2 and PD measures for R ≤ 10 were indistinguishable from the true means of segmented tissue compartments.

CONCLUSION

High-resolution IVMRI measures of T1, T2 and PD with a trained SVM can automatically classify normal, early and advanced atherosclerosis with high sensitivity and specificity. Replacing relaxometric MRI with SLAM yields good estimates of T1, T2 and PD an order-of-magnitude faster to facilitate IVMRI-based characterization of vessel disease.

Variability in Atherosclerotic Disease Progression within the Infrainguinal Arterial Circulation is Dependent on Both Patient and Anatomical Factors

BACKGROUND

Studies suggest 25% of patients with symptomatic peripheral arterial disease develop symptom progression over time, yet there is minimal data related to actual atherosclerotic progression.

METHODS

Patients who underwent consecutive duplex imaging of the lower limb arteries, at least 6 months apart with no intervening arterial intervention, were identified. Atherosclerotic burden was determined for both femoropopliteal (FP) and crural (CR) arterial segments utilizing the Bollinger score (BoS). Overall change in BoS over time was determined, and patients were divided into group 1: disease progression and group 2: no change/disease regression. Patient demographics, comorbidities, and long-term outcomes were collated.

RESULTS

A total of 215 FP segments (155 men; median age 74 years) were assessed with 82 limbs showing atherosclerotic disease progression. FP atherosclerotic progression was associated with increased age, a diagnosis of ischemic heart disease and hypertension, and a lack of prescription of both an antiplatelet therapy and an angiotensin-converting enzyme inhibitor (all P < 0.05). FP atherosclerotic progression was also associated with an increased longer term mortality rate. A total of 272 CR arterial segments (190 men; median age 74 years) were assessed with 86 limbs showing atherosclerotic disease progression. CR atherosclerotic disease progression was associated with a diagnosis of diabetes mellitus at baseline (P = 0.019).

CONCLUSIONS

A number of variable factors predict atherosclerotic progression. Differences exist between factors and the arterial segments affected (FP/CR). This suggests that underlying atherosclerotic processes may vary depending on arterial segment, warranting further investigation.