Polonsky T, Leeuwenburgh C, Ferrucci L, Peterson CA. 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.