Local association between endothelial dysfunction and intimal hyperplasia: relevance in peripheral artery disease

Fluid-structure interactions of peripheral arteries using a coupled in silico and in vitro approach

Vascular compliance is considered both a cause and a consequence of cardiovascular disease and a significant factor in the mid- and long-term patency of vascular grafts. However, the biomechanical effects of localised changes in compliance cannot be satisfactorily studied with the available medical imaging technologies or surgical simulation materials. To address this unmet need, we developed a coupled silico-vitro platform which allows for the validation of numerical fluid-structure interaction results as a numerical model and physical prototype. This numerical one-way and two-way fluid-structure interaction study is based on a three-dimensional computer model of an idealised femoral artery which is validated against patient measurements derived from the literature. The numerical results are then compared with experimental values collected from compliant arterial phantoms via direct pressurisation and ring tensile testing. Phantoms within a compliance range of 1.4-68.0%/100 mmHg were fabricated via additive manufacturing and silicone casting, then mechanically characterised via ring tensile testing and optical analysis under direct pressurisation with moderately statistically significant differences in measured compliance ranging between 10 and 20% for the two methods. One-way fluid-structure interaction coupling underestimated arterial wall compliance by up to 14.7% compared with two-way coupled models. Overall, Solaris™ (Smooth-On) matched the compliance range of the numerical and in vivo patient models most closely out of the tested silicone materials. Our approach is promising for vascular applications where mechanical compliance is especially important, such as the study of diseases which commonly affect arterial wall stiffness, such as atherosclerosis, and the model-based design, surgical training, and optimisation of vascular prostheses.

Prolonged sitting and peripheral vascular function: potential mechanisms and methodological considerations

Sitting time is associated with increased risks for subclinical atherosclerosis and cardiovascular disease development, and this is thought to be partially due to sitting-induced disturbances in macro- and microvascular function as well as molecular imbalances. Despite surmounting evidence supporting these claims, contributing mechanisms to these phenomena remain largely unknown. In this review, we discuss evidence for potential mechanisms of sitting-induced perturbations in peripheral hemodynamics and vascular function and how these potential mechanisms may be targeted using active and passive muscular contraction methods. Furthermore, we also highlight concerns regarding the experimental environment and population considerations for future studies. Optimizing prolonged sitting investigations may allow us to not only better understand the hypothesized sitting-induced transient proatherogenic environment but to also enhance methods and devise mechanistic targets to salvage sitting-induced attenuations in vascular function, which may ultimately play a role in averting atherosclerosis and cardiovascular disease development.

Flow-mediated dilation reference values for evaluation of endothelial function and cardiovascular health

AIMS

Endothelial function is essential for cardiovascular health, and flow-mediated dilation (FMD) is an established technique to measure it. This paper aims to assess FMD values in apparently healthy individuals and provides reference values to facilitate wider clinical use.

METHODS AND RESULTS

In 1,579 apparently healthy individuals (aged 18-76), fasted FMD values (data from 44 studies, 6 institutions, 22 operators) were normally distributed and inversely univariately correlated with age, body mass index, glucose, cholesterol, blood pressure, and brachial artery (BA) diameter. Significant multivariate predictors of FMD were age (-0.4%/decade), BMI (0.04%/kg/m2), smoking (-0.7%), and BA diameter (-0.44%/mm) that together explained 19% of the variability independent of operator, institution or ultrasound machine. Individuals in the high FMD tertile (>6.8%) were younger, had smaller BA diameter, lower blood pressure and cholesterol. In individuals with low- and intermediate fatal cardiovascular risk (SCORE), 26% and 53% of individuals, respectively, had FMD values in the low tertile (<5.4%). After adding data from 385 patients with stable coronary artery disease (CAD), ROC analysis (c = 0.841, P < 0.001) showed that FMD of >6.5% excluded CAD (95% sensitivity; 60% specificity) and FMD <3.1% excluded 95% healthy individuals (95% specificity, 31% sensitivity). A meta-analysis and meta-regression of 82 clinical trials (11 countries, n = 3,509) using similar FMD methodology showed that despite considerable heterogeneity (I2 = 0.97) FMD in healthy individuals was on average 6.4% (95%CI: 6.2%, 6.7%) with no significant differences between countries but a significant age-dependent decline (-0.3%/decade, R2 = 0.13).

CONCLUSIONS

We provide an age-adapted frame of FMD reference intervals in apparently healthy individuals for use as a biomarker of cardiovascular health. As the degree of vascular endothelial function integrates environmental and genetic factors with classical CV risk factors, FMD may more comprehensively classify individuals with and without standard modifiable cardiovascular risk factors and serve as a target for cardiovascular prevention.

Tissue Engineering and Targeted Drug Delivery in Cardiovascular Disease: The Role of Polymer Nanocarrier for Statin Therapy

Atherosclerosis-related coronary artery disease (CAD) is the leading cause of mortality and morbidity worldwide. This requires effective primary and secondary prevention in reducing the complications related to CAD; the regression or stabilization of the pathology remains the mainstay of treatment. Statins have proved to be the most effective treatment in reducing adverse effects, but there are limitations related to the administration and achievement of effective doses as well as side effects due to the lack of target-related molecular specificity. The implemented technological steps are polymers and nanoparticles for the administration of statins, as it has been seen how the conjugation of drug delivery systems (DDSs) with statins increases bioavailability by circumventing the hepatic–renal filter and increases the related target specificity, enhancing their action and decreasing side effects. Reduction of endothelial dysfunction, reduced intimal hyperplasia, reduced ischemia–reperfusion injury, cardiac regeneration, positive remodeling in the extracellular matrix, reduced neointimal growth, and increased reendothelialization are all drug-related effects of statins enhanced by binding with DDSs. Recent preclinical studies demonstrate how the effect of statins stimulates the differentiation of endogenous cardiac stem cells. Poly-lactic-co-glycolic acid (PLGA) seems to be the most promising DDS as it succeeds more than the others in enhancing the effect of the bound drug. This review intends to summarize the current evidence on polymers and nanoparticles for statin delivery in the field of cardiovascular disease, trying to shed light on this topic and identify new avenues for future studies.

Endothelial Progenitor Cells May Be Related to Major Amputation after Angioplasty in Patients with Critical Limb Ischemia

BACKGROUND

Critical limb ischemia represents an advanced stage of peripheral arterial disease. Angioplasty improves blood flow to the limb; however, some patients progress irreversibly to lower limb amputation. Few studies have explored the predictive potential of biomarkers during postangioplasty outcomes.

AIM

To evaluate the behavior of endothelial progenitor cells in patients with critical limb ischemia, in relation to their postangioplasty outcome.

METHODS

Twenty patients with critical limb ischemia, candidates for angioplasty, were enrolled. Flow-mediated dilation, as well as endothelial progenitor cells (subpopulations CD45+/CD34+/CD133+/CD184+ and CD45+/CD/34+/KDR[VEGFR-2]+ estimated by flow cytometry) from blood flow close to vascular damage, were evaluated before and after angioplasty. Association with lower limb amputation during a 30-day follow-up was analyzed.

RESULTS

Endothelial progenitor cells were related with flow-mediated dilation. A higher number of baseline EPCs CD45⁺CD34⁺KDR⁺, as well as an impaired reactivity of endothelial progenitor cells CD45⁺CD34⁺CD133⁺CD184⁺ after angioplasty, were observed in cases further undergoing major limb amputation, with a significant discrimination ability and risk (0.75, specificity 0.83 and RR 4.5 p < 0.05).

CONCLUSIONS

Endothelial progenitor cells were related with endothelial dysfunction, whereas a higher baseline number of the subpopulation CD45⁺CD34⁺KDR⁺, as well as an impaired reactivity of subpopulation CD45⁺CD34⁺CD133⁺CD184⁺ after angioplasty, showed a predictive ability for major limb amputation in patients with critical limb ischemia.

Age-Dependent Decline in Common Femoral Artery Flow-Mediated Dilation and Wall Shear Stress in Healthy Subjects

Femoral artery (FA) endothelial function is a promising biomarker of lower extremity vascular health for peripheral artery disease (PAD) prevention and treatment; however, the impact of age on FA endothelial function has not been reported in healthy adults. Therefore, we evaluated the reproducibility and acceptability of flow-mediated dilation (FMD) in the FA and brachial artery (BA) (n = 20) and performed cross-sectional FA- and BA-FMD measurements in healthy non-smokers aged 22−76 years (n = 50). FMD protocols demonstrated similar good reproducibility. Leg occlusion was deemed more uncomfortable than arm occlusion; thigh occlusion was less tolerated than forearm and calf occlusion. FA-FMD with calf occlusion was lower than BA-FMD (6.0 ± 1.1% vs 6.4 ± 1.3%, p = 0.030). Multivariate linear regression analysis indicated that age (−0.4%/decade) was a significant independent predictor of FA-FMD (R2 = 0.35, p = 0.002). The age-dependent decline in FMD did not significantly differ between FA and BA (pinteraction agexlocation = 0.388). In older participants, 40% of baseline FA wall shear stress (WSS) values were <5 dyne/cm2, which is regarded as pro-atherogenic. In conclusion, endothelial function declines similarly with age in the FA and the BA in healthy adults. The age-dependent FA enlargement results in a critical decrease in WSS that may explain part of the age-dependent predisposition for PAD.

Mechanical atherothrombectomy improves endothelial function through plaque burden reduction in PAD

Summary: Background: Endothelial dysfunction defines outcomes and serves as a surrogate parameter for the progression of cardiovascular disease. For symptomatic peripheral artery disease (PAD) endovascular treatment is the primary revascularization strategy, which affects endothelial function. Interventional mechanical atherothrombectomy (MATH) provides advantages when treating complex atherosclerotic and thrombotic lesions. We now aimed to determine the impact and mechanisms of MATH on endothelial function. Patients and methods: Endothelial function was determined using flow-mediated dilation (FMD) before and after lower limb intervention with a six-month follow-up in the target and control vessel in 15 PAD MATH+DCB treated patients and compared to 15 non-Math controls. In a further cohort of 20 patients the impact of MATH and DCB on vascular structure and virtual histology was assessed through intravascular ultrasound (IVUS) and compared to DCB treatment alone. Results: Improved endothelial function after 6 months was observed in both groups for the target and nontarget vessel. When comparing the changes from baseline endothelial function, treatment with MATH+DCB was superior to DCB treatment in the target vessel. IVUS revealed a greater improvement in luminal area and plaque burden reduction after MATH treatment. Virtual histology disclosed MATH-associated changes in plaque composition evidenced by alterations in fibrous volume and reductions in superficial calcium. Conclusions: We demonstrate an improved endothelial function after MATH treatment as compared to DCB treatment. The improved vessel function is evidenced by MATH-related plaque burden reduction, improved luminal gain and a decrease in superficial calcification. Clinicaltrials.gov: NCT04092972.

Detrimental effects of physical inactivity on peripheral and brain vasculature in humans: Insights into mechanisms, long-term health consequences and protective strategies

The growing prevalence of physical inactivity in the population highlights the urgent need for a more comprehensive understanding of how sedentary behaviour affects health, the mechanisms involved and what strategies are effective in counteracting its negative effects. Physical inactivity is an independent risk factor for different pathologies including atherosclerosis, hypertension and cardiovascular disease. It is known to progressively lead to reduced life expectancy and quality of life, and it is the fourth leading risk factor for mortality worldwide. Recent evidence indicates that uninterrupted prolonged sitting and short-term inactivity periods impair endothelial function (measured by flow-mediated dilation) and induce arterial structural alterations, predominantly in the lower body vasculature. Similar effects may occur in the cerebral vasculature, with recent evidence showing impairments in cerebral blood flow following prolonged sitting. The precise molecular and physiological mechanisms underlying inactivity-induced vascular dysfunction in humans are yet to be fully established, although evidence to date indicates that it may involve modulation of shear stress, inflammatory and vascular biomarkers. Despite the steady increase in sedentarism in our societies, only a few intervention strategies have been investigated for their efficacy in counteracting the associated vascular impairments. The current review provides a comprehensive overview of the evidence linking acute and short-term physical inactivity to detrimental effects on peripheral, central and cerebral vascular health in humans. We further examine the underlying molecular and physiological mechanisms and attempt to link these to long-term consequences for cardiovascular health. Finally, we summarize and discuss the efficacy of lifestyle interventions in offsetting the negative consequences of physical inactivity.

Cocoa flavanol consumption improves lower extremity endothelial function in healthy individuals and people with type 2 diabetes

Background: diabetes and age are major risk factors for the development of lower extremity peripheral artery disease (PAD). Cocoa flavanol (CF) consumption is associated with lower risk for PAD and improves brachial artery (BA) endothelial function. Objectives: to assess if femoral artery (FA) endothelial function and dermal microcirculation are impaired in individuals with type 2 diabetes mellitus (T2DM) and evaluate the acute effect of CF consumption on FA endothelial function. Methods: in a randomised, controlled, double-blind, cross-over study, 22 individuals (n = 11 healthy, n = 11 T2DM) without cardiovascular disease were recruited. Participants received either 1350 mg CF or placebo capsules on 2 separate days in random order. Endothelial function was measured as flow-mediated dilation (FMD) using ultrasound of the common FA and the BA before and 2 hours after interventions. The cutaneous microvasculature was assessed using optical coherence tomography angiography. Results: baseline FA-FMD and BA-FMD were significantly lower in T2DM (FA: 3.2 ± 1.1% [SD], BA: 4.8 ± 0.8%) compared to healthy (FA: 5.5 ± 0.7%, BA: 6.0 ± 0.8%); each p < 0.001. Whereas in healthy individuals FA-FMD did not significantly differ from BA-FMD (p = 0.144), FA-FMD was significantly lower than BA-FMD in T2DM (p = 0.003) indicating pronounced and additional endothelial dysfunction of lower limb arteries (FA-FMD/BA-FMD: 94 ± 14% [healthy] vs. 68 ± 22% [T2DM], p = 0.007). The baseline FA blood flow rate (0.42 ± 0.23 vs. 0.73 ± 0.35 l min^-1, p = 0.037) and microvascular dilation in response to occlusion in hands and feet were significantly lower in T2DM subjects than in healthy ones. CF increased both FA- and BA-FMD at 2 hours, compared to placebo, in both healthy and T2DM subgroups (FA-FMD effect: 2.9 ± 1.4%, BA-FMD effect 3.0 ± 3.5%, each p_intervention< 0.001). In parallel, baseline FA blood flow and microvascular diameter significantly increased in feet (3.5 ± 3.5 μm, p_intervention< 0.001) but not hands. Systolic blood pressure and pulse wave velocity significantly decreased after CF in both subgroups (-7.2 ± 9.6 mmHg, p_intervention = 0.004; -1.3 ± 1.3 m s^-1, p_intervention = 0.002). Conclusions: individuals with T2DM exhibit decreased endothelial function that is more pronounced in the femoral than in the brachial artery. CFs increase endothelial function not only in the BA but also the FA both in healthy individuals and in those with T2DM who are at increased risk of developing lower extremity PAD and foot ulcers.

Ankle-brachial index predicts renal outcomes and all-cause mortality in high cardiovascular risk population: a nationwide prospective cohort study in CORE project

BACKGROUND

Low ankle-brachial index (ABI) related ischemic events are common among individuals with chronic kidney disease (CKD). It is also associated with an increased risk of rapid renal function decline. The presence of peripheral artery disease (PAD) with low ABI among patients with high cardiovascular (CV) risk increases limb loss and mortality.

AIMS

To estimate the association between abnormal ABI and renal endpoints and all-cause mortality.

METHODS

A multicenter prospective cohort study was conducted among subjects with high CV risk or established CV diseases in Thailand. The subjects were divided into 3 groups based on ABI at baseline > 1.3, 0.91-1.3, and ≤ 0.9, respectively. Primary composite outcome consisted of estimated glomerular filtration rate (eGFR) decline over 40%, eGFR less than 15 mL/min/1.73 m², doubling of serum creatinine and initiation of dialysis. The secondary outcome was all-cause mortality. Cox regression analysis and Kaplan-Meier curve were performed.

RESULTS

A total of 5543 subjects (3005 men and 2538 women) were included. Cox proportional hazards model showed a significant relationship of low ABI (ABI ≤ 0.9) and primary composite outcome and all-cause mortality. Compared with the normal ABI group (ABI 0.91-1.3), subjects with low ABI at baseline significantly had 1.42-fold (95% CI 1.02-1.97) and 2.03-fold (95% CI 1.32-3.13) risk for the primary composite outcome and all-cause mortality, respectively, after adjusting for variable factors.

CONCLUSION

Our study suggested that PAD independently predicts the incidence of renal progression and all-cause mortality among Thai patients with high CV risk.

Effect of cilostazol on arteriovenous fistula in hemodialysis patients

BACKGROUND

The maturation and patency of permanent vascular access are critical in patients requiring hemodialysis. Although numerus trials have been attempted to achieve permanently patent vascular access, little have been noticeable. Cilostazol, a phosphodiesterase-3 inhibitor, has been shown to be effective in peripheral arterial disease including vascular injury-induced intimal hyperplasia. We therefore aimed to determine the effect of cilostazol on the patency and maturation of permanent vascular access.

METHODS

This single-center, retrospective study included 194 patients who underwent arteriovenous fistula surgery to compare vascular complications between the cilostazol (n=107) and control (n=87) groups.

RESULTS

The rate of vascular complications was lower in the cilostazol group than in the control group (36.4% vs. 51.7%; p=0.033), including maturation failure (2.8% vs. 11.5%; p=0.016). The rate of reoperation due to vascular injury after hemodialysis initiation following fistula maturation was also significantly lower in the cilostazol group than in the control group (7.5% vs. 28.7%; p<0.001). However, there were no significant differences in the requirement for percutaneous transluminal angioplasty (PTA), rate of PTA, and the interval from arteriovenous fistula surgery to PTA between the cilostazol and control groups.

CONCLUSION

Cilostazol might be beneficial for the maturation of permanent vascular access in patients requiring hemodialysis.

Cardio-ankle vascular index with renal progression and mortality in high atherosclerosis risk: a prospective cohort study in CORE-Thailand

BACKGROUND

Increased arterial stiffness is linked to markers of endothelial dysfunction and vasculopathy such as albuminuria, vascular calcification, left ventricular hypertrophy and cardiovascular (CV) diseases. Studies of arterial stiffness on renal progression are limited.

OBJECTIVE

The study aimed to evaluate the association between high cardio-ankle vascular index (CAVI) and renal endpoint and all-cause mortality in a Thai population with high atherosclerosis risk.

METHODS

A multicenter prospective cohort study was conducted among subjects with high CV risk or established CV diseases in Thailand. Subjects were divided into 3 groups with mean CAVI < 8, 8-8.9, and ≥ 9, respectively. Primary composite outcome consisted of estimated glomerular filtration rate (eGFR) decline over 40%, eGFR less than 15 mL/min/1.73 m², doubling of serum creatinine, initiation of dialysis and death related to renal causes. The secondary outcomes were all-cause mortality, CV mortality and eGFR decline.

RESULTS

A total of 4898 subjects (2743 men and 2155 women) were enrolled. Cox proportional hazards model showed a significant relationship of high CAVI (CAVI ≥ 9) and primary composite outcome. Subjects with high CAVI at baseline had a 1.45-fold (95% CI 1.13-1.84) significant risk for the primary composite outcome and 1.72-fold (95% CI 1.12-2.63) risk for all-cause mortality, compared with normal CAVI (CAVI < 8). After stepwise multivariate analysis, the high CAVI group was only positively associated with primary composite outcome. Kaplan-Meier curve of the primary composite outcome and all-cause mortality demonstrated the worst survival in the high CAVI group (log-rank test with P < 0.05).

CONCLUSION

In a Thai cohort with high atherosclerosis risk, increased arterial stiffness was a risk factor for worsening renal function, including end-stage renal disease and initiation of dialysis.

In vivo assessment of endothelial permeability of coronary lesions with variable degree of stenosis using an albumin-binding MR probe

MR imaging with an albumin-binding probe enables the visualization of endothelial permeability and damage in the arterial system. The goal of this study was to compare signal enhancement of lesions with different grades of stenosis segments on molecular CMR in combination with the albumin-binding probe gadofosveset. This prospective clinical study included patients with symptoms suggestive of coronary artery disease (CAD). Patients underwent gadofosveset-enhanced cardiovascular magnetic resonance (CMR) imaging and x-ray angiography (QCA) within 24 h. CMR imaging was performed prior to and 24 h following the administration of gadofosveset. Contrast-to-noise ratios (CNRs) between segments with different grades of stenosis were compared. Overall, n = 203 segments of 26 patients were included. Lesions with more than > 70% stenosis demonstrated significantly higher CNRs compared to lesions < 70% (7.6 ± 8.3 vs. 2.5 ± 4.9; p < 0.001). Post-stenotic segments of lesions > 70% stenosis showed significant higher signal enhancement compared to segments located upstream of these lesions (7.3 ± 8.8 vs. 2.8 ± 2.2; p = 0.02). No difference in signal enhancement between segments proximal and distal of lesions with stenosis greater than 50% was measured (3.3 ± 2.8 vs. 2.4 ± 2.7; p = 0.18). ROC analysis for the detection of lesions ≥ 70% revealed an area under the curve of 0.774 (95% CI 0.681-0.866). This study suggests that relevant coronary stenosis and their down-stream segments are associated with increased signal enhancement on Gadofosveset-enhanced CMR, suggesting a higher endothelial permeability in these lesions. An albumin-binding MR probe could represent a novel in vivo biomarker for the identification and characterization of these vulnerable coronary segments.

The impact of percutaneous peripheral interventions on endothelial function

Background: Treatment of symptomatic peripheral artery disease (PAD) through endovascular interventions is the primary revascularization strategy. Interventions restore perfusion but may cause severe injury to the vascular endothelium, which regulates vascular tone. Endothelial dysfunction is involved in the progression of cardiovascular disease, with higher incidences of vascular events. We aimed to determine the impact of percutaneous interventions on change in endothelial function. Patients and methods: Endothelial function was determined using flow-mediated dilation (FMD) before, the day after lower limb intervention with paclitaxel-coated balloons or stent guided interventions and after a six-month follow-up in the target limb, control limb and the systemic circulation in 42 PAD patients aged 70.2±9 years and 66% men. Additionally, macro- and microvascular function were assessed. Results: In PAD patients aged 70.2±9 years and 66% men, we observed an immediate enhancement of macro-, microvascular and endothelial function after endovascular treatment (FMD of superficial femoral artery (SFA) 3.7±0.2% to 4.1±0.1%, n=42, p=0.02), a sustained long-term improvement after 6-months (FMD SFA 3.7±0.2% to 4.2±0.1%, n=42, p=0.01), and moreover an improved systemic endothelial function (FMD brachial artery 4.3±0.1% to 4.7±0.2, n=42, p=0.01) following peripheral interventions. Subgroup analysis however revealed that following paclitaxel-based percutaneous intervention, the paclitaxel dosage applied was inversely related to the chronic improvement in local endothelial function (r=-0.6, n=22, p=0.005) without evidence for systemic effects (r=-0.25, p=0.27). Conclusions: We demonstrate an improved local and systemic endothelial function after treatment of atherosclerotic peripheral disease with a distinguished response after endovascular intervention with higher dosage of applied paclitaxel restraining the benefits. Further studies have to determine the optimal interventional strategy with respect to different treatment modalities to maintain vessel functions.

Angioplasty of Flow-Limiting Stenosis Reduces Aortic and Brachial Blood Pressure in Patients With Peripheral Artery Disease

Background Arterial hypertension affects cardiovascular outcome in patients with peripheral artery disease (PAD). We hypothesized that angioplasty of peripheral arterial stenoses decreases aortic (aBP) and brachial blood pressure (bBP). Methods and Results In an index cohort (n=30), we simultaneously measured aBP, bBP, augmentation index (AIx), and aortic pulse wave velocity (PWV) before and after angioplasty of the iliac and femoropopliteal arteries; diagnostic angiography served as a control. In an all-comer registry cohort (n=381), we prospectively measured bBP in patients scheduled for angioplasty of the iliac, femoral, and crural arteries or diagnostic angiography. Systolic aBP decreased after iliac (Δ-25 mmHg; 95% CI, -30 to -20; P<0.0001) and femoropopliteal angioplasty (Δ-12 mmHg; 95% CI, -17 to -5; P<0.0001) as compared with diagnostic angiography. Diastolic aBP decreased after iliac (Δ-9 mmHg; 95% CI, -13 to -1; P=0.01) but not femoropopliteal angioplasty. In parallel, AIx significantly dropped, whereas PWV remained stable. In the registry cohort, systolic bBP decreased after angioplasty of the iliac (Δ-17 mmHg; 95% CI, -31 to -8; P=0.0005) and femoropopliteal arteries (Δ-10 mmHg; 95% CI, -23 to -1; P=0.04) but not the crural arteries, as compared with diagnostic angiography. Diastolic bBP decreased after iliac (Δ-10 mmHg; 95% CI, -17 to -2; P=0.01) and femoropopliteal angioplasty (Δ-9 mmHg; 95% CI, -15 to -1; P=0.04). Multivariate analysis identified baseline systolic bBP and site of lesion as determinants of systolic bBP drop after endovascular treatment. Conclusions Angioplasty of flow-limiting stenoses in patients with peripheral artery disease lowers aortic and brachial blood pressure with more pronounced effects at more proximal lesion sites and elevated baseline systolic blood pressure. These data indicate a role of endovascular treatment to acutely optimize blood pressure in patients with peripheral artery disease. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT02728479.

Effect of cilostazol on arteriovenous fistula in hemodialysis patients

BACKGROUND

The maturation and patency of permanent vascular access are critical in patients requiring hemodialysis. Although numerus trials have been attempted to achieve permanently patent vascular access, little have been noticeable. Cilostazol, a phosphodiesterase-3 inhibitor, has been shown to be effective in peripheral arterial disease including vascular injury-induced intimal hyperplasia. We therefore aimed to determine the effect of cilostazol on the patency and maturation of permanent vascular access.

METHODS

This single-center, retrospective study included 194 patients who underwent arteriovenous fistula surgery to compare vascular complications between the cilostazol (n=107) and control (n=87) groups.

RESULTS

The rate of vascular complications was lower in the cilostazol group than in the control group (36.4% vs. 51.7%; p=0.033), including maturation failure (2.8% vs. 11.5%; p=0.016). The rate of reoperation due to vascular injury after hemodialysis initiation following fistula maturation was also significantly lower in the cilostazol group than in the control group (7.5% vs. 28.7%; p<0.001). However, there were no significant differences in the requirement for percutaneous transluminal angioplasty (PTA), rate of PTA, and the interval from arteriovenous fistula surgery to PTA between the cilostazol and control groups.

CONCLUSION

Cilostazol might be beneficial for the maturation of permanent vascular access in patients requiring hemodialysis.

Polymers and Nanoparticles for Statin Delivery: Current Use and Future Perspectives in Cardiovascular Disease

Atherosclerosis-related coronary artery disease (CAD) is one of the leading sources of mortality and morbidity in the world. Primary and secondary prevention appear crucial to reduce CAD-related complications. In this scenario, statin treatment was shown to be clinically effective in the reduction of adverse events, but systemic administration provides suboptimal results. As an attempt to improve bioavailability and effectiveness, polymers and nanoparticles for statin delivery were recently investigated. Polymers and nanoparticles can help statin delivery and their effects by increasing oral bioavailability or enhancing target-specific interaction, leading to reduced vascular endothelial dysfunction, reduced intimal hyperplasia, reduced ischemia-reperfusion injury, increased cardiac regeneration, positive remodeling in the extracellular matrix, reduced neointimal growth and increased re-endothelization. Moreover, some innovative aspects described in other cardiovascular fields could be translated into the CAD scenario. Recent preclinical studies are underlining the effect of statins in the stimulation and differentiation of endogenous cardiac stem cells, as well as in targeting of local adverse conditions implicated in atherosclerosis, and statin delivery through poly-lactic-co-glycolic acid (PLGA) appears the most promising aspect of current research to enhance drug activity. The present review intends to summarize the current evidence about polymers and nanoparticles for statin delivery in the field of cardiovascular disease, trying to shed light on this topic and identify new avenues for future studies.

Pattern of organ remodeling in chronic non-communicable diseases is due to endogenous regulations and falls under the category of Kauffman's self-organization: A case of arterial neointimal pathology

Clinical diagnosis is based on analysis of pathologic findings that may result in perceived patterns. The same is true for diagnostic pathology: Pattern analysis is a foundation of the histopathology-based diagnostic system and, in conjunction with clinical and laboratory findings, forms a basis for the classification of diseases. Any histopathology diagnosis is based on the explicit assumption that the same diseased condition should result in formation of the same (or highly similar) morphologic patterns in different individuals; it is a standard approach in microscopic pathology, including that of non-communicable chronic diseases with organ remodeling. During fifty years of examining diseased tissues under microscopy, I keep asking the same question: Why is a similarity of patterns expected for chronic organ remodeling? For infection diseases, xenobiotic toxicity and deficiencies forming an identical pathologic pattern in different individuals is understandable and logical: The same infection, xenobiotic, or deficiency strikes the same target, which results in identical pathology. The same is true for Mendelian diseases: The same mutations lead to the same altered gene expressions and the same pathologic pattern. But why does this regularity hold true for chronic diseases with organ remodeling? Presumable causes (or risk factors) for a particular chronic disease differ in magnitude and duration between individuals, which should result in various series of transformations. Yet, mysteriously enough, pathological remodeling in a particular chronic disease always falls into a main dominating pattern, perpetuating and progressing in a similar fashion in different patients. Furthermore, some chronic diseases of different etiologies and dissimilar causes/risk factors manifest as identical or highly similar patterns of pathologic remodeling. HYPOTHESIS: I hypothesize that regulations governing a particular organ's chronic remodeling were selected in evolution as the safest response to various insults and physiologic stress conditions. This hypothesis implies that regulations directing diseased chronic remodeling always preexist but normally are controlled; this control can be disrupted by a diverse range of non-specific signals, liberating the pathway for identical pathologic remodeling. This hypothesis was tested in an analysis of arterial neointimal formation, the identical pathology occurring in different diseases and pathological conditions: graft vascular disease in organ transplantation, in-stent restenosis, peripheral arterial diseases, idiopathic intimal hyperplasia, Kawasaki disease, coronary atherosclerosis and as reaction to drugs. The hypothesis suggests that arterial intimal cells are poised between only two alternative pathways: the pathway with controlled intimal cell proliferation or the pathway where such control is disrupted, ultimately leading to the progressive neointimal pathology. By this property the arterial neointimal formation constitutes a special case of Kauffman's self-organization. This new hypothesis gives a parsimonious explanation for identical pathological patterns of arterial remodeling (neointimal formation), which occurs in diseases of different etiologies and due to dissimilar causes/risk factors, or without any etiology and causes/risk factors at all. This new hypothesis also suggests that regulation facilitating intimal cell proliferation cannot be overwritten or annulled because this feature is vital for arterial differentiation, cell renewal, and integrity. This hypothesis suggests that studying numerous, and likely interchangeable, non-specific signals that disrupt regulation controlling intimal cell proliferation is unproductive; instead, a study of the controlling regulation(s) itself should be a priority of our research.

Microangiopathy in Naifold Videocapillaroscopy and Its Relations to sE- Selectin, Endothelin-1, and hsCRP as Putative Endothelium Dysfunction Markers among Adolescents with Raynaud's Phenomenon

The aim of this study was to analyze the relationship between the qualitative abnormalities on nailfold videocapillaroscopy (NVC), and the concentrations of selected biomarkers (sE-selectin, endothelin-1, high-sensitivity c-reactive protein (hsCRP)) and lipid metabolism parameters in children and adolescents with Raynaud’s phenomenon (RP). Raynaud’s phenomenon, to assess whether nailfold capillary changes may reflect the degree of systemic blood vessel abnormalities. The study group included 66 patients (34 undifferentiated—uRP and 32 secondary—sRP) aged 6–19 years and the control group. In both groups, NVC was performed and the selected biomarkers were measured (sE-selectin, endothelin-1, hsCRP) and lipid profile. Endothelin-1, sE-selectin and hsCRP concentrations in patients from both RP groups were significantly higher; concentration of HDL fraction was significantly lower compared with the control group. The analysis of multiple linear regression demonstrated that megacapillaries most strongly determine the sE-selectin value (p = 0.04) and hsCRP (p = 0.03). Both the total cholesterol and low-density lipoprotein (LDL) fraction concentrations were determined by the presence of avascular areas (p = 0.02). In conclusion, specific pathologic NVC changes were associated with higher endothelial damage biomarkers concentration and adverse changes in the lipid profile.

Prognostic implications of peripheral artery disease in coronary artery disease

Prevalence of peripheral arterial disease in patients with coronary artery disease is considerably higher than in the general population. A graded increase in the risk of major cardiovascular events in a variety of clinical settings is associated with the number of arterial beds affected by peripheral arterial disease. This is not surprising, considering that both coronary artery disease and peripheral arterial disease are linked to a higher prevalence of cardiovascular risk factors and a greater incidence of atherosclerotic burden. Aggressive lipid lowering therapy is associated with less coronary and peripheral arterial disease progression and greater regression. On the contrary, blood pressure therapy should be carefully managed, considering the association of both high and low values of pressure with adverse outcomes.

Research Toolbox for Peripheral Arterial Disease - Minimally Invasive Assessment of the Vasculature and Skeletal Muscle

In 2010, more than 200 million people were afflicted with peripheral arterial disease (PAD). Because it is atherosclerotic in etiology, it is not surprising that PAD is a leading cause of cardiovascular morbidity. Cardiovascular disease (CVD) risk can be decreased if ambulatory physical function is improved. However, physical function is limited by a mismatch between oxygen supply and demand in the legs, which results in exertional pain, leg weakness, and balance problems. Therefore, a key factor for improving physical function, and decreasing CVD outcomes, is ensuring oxygen supply meets the oxygen demand. The purpose of this review is to highlight and evaluate practical and minimally invasive tools for assessing PAD etiology, with a specific focus on tools suited to studies focusing on improving physical function and CVD outcomes. Specifically, the macrovascular, microvascular, and skeletal muscle pathology of PAD is briefly outlined. Subsequently, the tools for assessing each of these components is discussed, including, where available, the evidence to contextualize these tools to PAD pathology as well as physical function and CVD outcomes. The goal of this review is to guide researchers to the appropriate tools with respect to their methodological design.

Review of biologic and behavioral risk factors linking depression and peripheral artery disease

The incidence of depression has been rising rapidly, and depression has been recognized as one of the world’s leading causes of disability. More recently, depression has been associated with an increased risk of symptomatic atherosclerotic disease as well as worse perioperative outcomes in patients with cardiovascular disease. Additionally, recent studies have demonstrated an association between depression and peripheral artery disease (PAD), which has been estimated to affect more than 200 million people worldwide. These studies have identified that depression is associated with poor functional and surgical outcomes in patients with PAD. Although the directionality and specific mechanisms underlying this association have yet to be clearly defined, several biologic and behavioral risk factors have been identified to play a role in this relationship. These factors include tobacco use, physical inactivity, medical non-adherence, endothelial and coagulation dysfunction, and dysregulation of the hypothalamic-pituitary-adrenal axis, autonomic system, and immune system. In this article, we review these potential mechanisms and the current evidence linking depression and PAD, as well as future directions for research and interventional strategies. Understanding and elucidating this relationship may assist in preventing the development of PAD and may improve the care that patients with PAD and comorbid depression receive.

The relationship of renal function to segmental vascular stiffness, ankle-brachial index, and peripheral artery disease

The authors consecutively assessed various arterial pulse-wave velocity (PWV) indices and ankle-brachial index (ABI) by an automatic device (VP2000, OMRON Health Care Co. Ltd., Kyota, Japan) in outpatients with ≥ 1 cardiovascular risk. PAD was defined as ABI ≤ 0.9. Among 2309 outpatients (mean age 62.4 years), worse renal function was associated with higher brachial-ankle PWV, heart-carotid PWV, heart-femoral PWV (hf-PWV), and lower ABI (all P < .001). Multivariate regression models showed independent associations between lower eGFR, lower ABI (Coef: 0.42 & 0.41 for right and left), higher hf-PWV (Coef: -11.4 [95% CI: -15.4, -7.3]) and greater PAD risk (adjusted OR: 0.83 [95% CI: 0.76, 0.91], all P < .05). eGFR set at 77 mL/min/1.73m² was observed to be useful clinical cutoff (c-statistics: 0.67) for identifying PAD (P for ΔAUROC: .009; likelihood X² : 93.82 to 137.43, P < .001) when superimposed on clinical risks. This study suggested early renal insufficiency is tightly linked to region-specific vascular stiffness and PAD.

Cilostazol attenuates intimal hyperplasia in a mouse model of chronic kidney disease

Intimal hyperplasia (IH) is a common cause of vasculopathy due to direct endothelial damage (such as post-coronary revascularization) or indirect injury (such as chronic kidney disease, or CKD). Although the attenuation of coronary revascularization-induced IH (direct-vascular-injury-induced IH) by cilostazol, a phosphodiesterase III inhibitor, has been demonstrated, our understanding of the effect on CKD-induced IH (indirect-vascular-injury-induced IH) is limited. Herein, we tested if cilostazol attenuated CKD-induced IH in a mouse model of ischemic-reperfusion injury with unilateral nephrectomy (Chr I/R), a normotensive non-proteinuria CKD model. Cilostazol (50 mg/kg/day) or placebo was orally administered once daily from 1-week post-nephrectomy. At 20 weeks, cilostazol significantly attenuated aortic IH as demonstrated by a 34% reduction in the total intima area with 50% and 47% decreases in the ratios of tunica intima area/tunica media area and tunica intima area/(tunica intima + tunica media area), respectively. The diameters of aorta and renal function were unchanged by cilostazol. Interestingly, cilostazol decreased miR-221, but enhanced miR-143 and miR-145 in either in vitro or aortic tissue, as well as attenuated several pro-inflammatory mediators, including asymmetrical dimethylarginine, high-sensitivity C-reactive protein, vascular endothelial growth factor in aorta and serum pro-inflammatory cytokines (IL-6 and TNF-α). We demonstrated a proof of concept of the effectiveness of cilostazol in attenuating IH in a Chr I/R mouse model, a CKD model with predominantly indirect-vascular-injury-induced IH. These considerations warrant further investigation to develop a new primary prevention strategy for CKD-related IH.

Flow Mediated Dilatation as a Biomarker in Vascular Surgery Research

Endothelial dysfunction is one of the hallmarks of atherogenesis, and correlates with many cardiovascular risk factors. One of the features of endothelial dysfunction is the loss of nitric oxide (NO) bioavailability, resulting in derangements in the vasodilatory response of the vessel wall. Flow mediated dilatation (FMD) of the brachial artery is an accepted method for non-invasive assessment of systemic endothelial function. FMD is examined extensively in the context of cardiovascular research, and has been utilised as a routine assessment in large cohorts such as the Framingham Heart Study, Young Finns Study, and Gutenberg Heart Study. However, FMD is less known in the context of vascular surgery research, despite the similarities between the underpinning disease mechanisms. This review will provide a summary of FMD in terms of its history of development and the conduct of the test in research settings. It will further highlight the key literature of FMD as a biomarker for vascular surgeons, particularly in the context of abdominal aortic aneurysms and lower limb peripheral arterial disease.

Mitochondrial Bioenergetics in the Metabolic Myopathy Accompanying Peripheral Artery Disease

Peripheral artery disease (PAD) is a serious but relatively underdiagnosed and undertreated clinical condition associated with a marked reduction in functional capacity and a heightened risk of morbidity and mortality. The pathophysiology of lower extremity PAD is complex, and extends beyond the atherosclerotic arterial occlusion and subsequent mismatch between oxygen demand and delivery to skeletal muscle mitochondria. In this review, we evaluate and summarize the available evidence implicating mitochondria in the metabolic myopathy that accompanies PAD. Following a short discussion of the available in vivo and in vitro methodologies to quantitate indices of muscle mitochondrial function, we review the current evidence implicating skeletal muscle mitochondrial dysfunction in the pathophysiology of PAD myopathy, while attempting to highlight questions that remain unanswered. Given the rising prevalence of PAD, the detriment in quality of life for patients, and the associated significant healthcare resource utilization, new alternate therapies that ameliorate lower limb symptoms and the functional impairment associated with PAD are needed. A clear understanding of the role of mitochondria in the pathophysiology of PAD may contribute to the development of novel therapeutic interventions.

ABO blood group is associated with peripheral arterial disease in African Americans: The Multi-Ethnic Study of Atherosclerosis (MESA)

INTRODUCTION

Peripheral artery disease (PAD) affects 8.5 million Americans and thus improving our understanding of PAD is critical to developing strategies to reduce disease burden. The objective of the study was to determine the association of ABO blood type with ankle brachial index (ABI) as well as prevalent and incident PAD in a multi-ethnic cohort.

METHODS

The Multi-Ethnic Study of Atherosclerosis includes non-Hispanic White, African, Hispanic, and Chinese Americans aged 45-84. ABO blood type was estimated using ABO genotypes in 6027 participants who had ABI assessed at the baseline exam. Associations with ABO blood type were evaluated categorically and under an additive genetic model by number of major ABO alleles. After excluding those with ABI>1.4, prevalent PAD was defined as ABI≤0.9 at baseline and incident PAD as ABI≤0.9 for 5137 participants eligible for analysis.

RESULTS

There were 222 prevalent cases and 239 incident cases of PAD. In African Americans, each additional copy of the A allele was associated with a 0.02 lower baseline ABI (p=0.006). Each copy of the A allele also corresponded to 1.57-fold greater odds of prevalent PAD (95% CI, 1.17-2.35; p=0.004), but was not associated with incident PAD. No associations were found in other racial/ethnic groups for ABI, prevalent PAD, or incident PAD across all races/ethnicities.

CONCLUSIONS

Blood type A and the A allele count were significantly associated with baseline ABI and prevalent PAD in African Americans. Further research is needed to confirm and study the mechanisms of this association in African Americans.

Predictors of change in omega-3 index with fish oil supplementation in peripheral artery disease

BACKGROUND

The omega-3 index represents the red blood cell (RBC) content of two major long-chain n-3 polyunsaturated fatty acids (PUFAs), eicosapentaenoic acid, and docosahexaenoic acid. We sought to determine factors associated with a favorable response to fish oil treatment and to characterize changes in RBC PUFAs associated with fish oil supplementation.

METHODS

This study was a secondary analysis of the OMEGA-PAD I trial, a randomized, double-blinded, placebo-controlled trial investigating short-duration, high-dose n-3 PUFA oral supplementation on endothelial function and inflammation in subjects with peripheral arterial disease. Patients with mild to severe claudication received either 4.4 g of fish oil providing 2.6 g of eicosapentaenoic acid and 1.8 g of docosahexaenoic acid daily (n = 40) or placebo capsules (n = 40) for 1 mo. The RBC fatty acid content was measured by gas chromatography and expressed as a percent of total fatty acids. The change in omega-3 index was calculated as the difference between pre- and post-supplementation in the fish oil and placebo groups. Univariate analysis identified predictors of change in omega-3 index, with these variables included in our multivariable model.

RESULTS

In the fish oil group, there was an increase in the omega-3 index (5.1± 1.3% to 9.0± 1.8%; P < 0.0001), whereas there was no change in the control group. Factors associated with a favorable response (i.e., greater than the median change of 4.06%) included a lower body mass index and higher concentrations of low-density lipoproteins. Other demographic and/or lifestyle factors such as age, race, or smoking status were unrelated to the response. Oral n-3 PUFA supplementation also decreased the n-6 PUFA content in RBCs.

CONCLUSIONS

Short-term, high-dose n-3 PUFA supplementation increases the omega-3 index to a greater extent in patients with a lower body mass index and higher total and low-density lipoprotein cholesterol levels.

Patient-Specific Flow Descriptors and Normalized wall index in Peripheral Artery Disease: a Preliminary Study

BACKGROUND AND AIMS

MRI-based hemodynamics have been applied to study the relationship between time-averaged wall shear stresses (TAWSS), oscillatory shear index (OSI) and atherosclerotic lesions in the coronary arteries, carotid artery, and human aorta. However, the role of TAWSS and OSI are poorly understood in lower extremity arteries. The aim of this work was to investigate the feasibility of hemodynamic assessment of the superficial femoral artery (SFA) in patients with peripheral artery disease (PAD) and we hypothesized that there is an association between TAWSS and OSI, respectively, and atherosclerotic burden expressed as the normalized wall index (NWI).

METHODS

Six cases of 3D vascular geometries of the SFA and related inlet/outlet flow conditions were extracted from patient-specific MRI data including baseline, 12 and 24 months. Blood flow simulations were performed to compute flow descriptors, including TAWSS and OSI, and NWI.

RESULTS

NWI was correlated positively with TAWSS (correlation coefficient: r = 0.592; p < 0.05). NWI was correlated negatively with OSI (correlation coefficient: r = -0.310, p < 0.01). Spatially averaged TAWSS and average NWI increased significantly between baseline and 24-months, whereas OSI decreased over 2-years.

CONCLUSIONS

In this pilot study with a limited sample size, TAWSS was positively associated with NWI, a measure of plaque burden, whereas OSI showed an inverse relationship. However, our findings need to be verified in a larger prospective study. MRI-based study of hemodynamics is feasible in the superficial femoral artery.

Acute effects of different types of aerobic exercise on endothelial function and arterial stiffness

BACKGROUND

Chronic aerobic exercise training is associated with improved endothelial function and arterial stiffness and favourable long-term cardiovascular effects.

DESIGN

We investigated the acute effects of continuous moderate intensity aerobic exercise (CAE) and high intensity interval aerobic exercise (hIAE) on endothelial function and arterial stiffness in healthy participants.

METHODS

Twenty healthy men were recruited to this cross-over study. They participated in two exercise sessions: (a) CAE, volume at 50% of maximum aerobic work for 30 minutes; and (b) hIAE, interval maximum aerobic work for 30 minutes. Endothelial function was evaluated by flow-mediated dilation in the brachial artery. The carotid femoral pulse wave velocity and the femoral dorsalis pedis pulse wave velocity were measured as indices of central aortic and peripheral arterial stiffness. Measurements were carried out before and immediately after each exercise session.

RESULTS

There was no statistically significant difference in the baseline measurements before CAE and hIAE with respect to flow-mediated dilation, the carotid femoral pulse wave velocity and the femoral dorsalis pedis pulse wave velocity (p = NS). Both CAE and hIAE significantly improved the flow-mediated dilation compared with baseline (p < 0.001). Similarly, the femoral dorsalis pedis pulse wave velocity was improved after CAE and hIAE (p < 0.005), whereas the carotid femoral pulse wave velocity was not significantly affected (p = NS).

CONCLUSION

Both CAE and hIAE can favourably affect endothelial function, suggesting another cardioprotective effect of acute exercise. These types of aerobic exercise have a different impact on the central and peripheral arterial stiffness.