Arterial Disease and Vascular Access in Diabetic Patients

Long-term patency of arteriovenous fistulas for hemodialysis: A decade's experience in a transplant unit

BACKGROUND

The heterogeneous quality of studies on arteriovenous fistulas outcome, with variable clinical settings and large variations in definitions of patency and failure rates, leads to frequent misinterpretations and overestimation of arteriovenous fistula patency. Hence, this study aimed to provide realistic and clinically relevant long-term arteriovenous fistula outcomes.

METHODS

We retrospectively analyzed all autologous arteriovenous fistulas at our center over a 10-year period (2012-2022). Primary and secondary patency analysis was conducted using the Kaplan-Meier method; multivariate analysis of variance was used to detect outcome predictors. Vascular access-specific endpoints were defined according to the European guidelines on vascular access formation.

FINDINGS

Of 312 arteriovenous fistulas, 57.5% (n = 181) were radio-cephalic (RC_AVF), 35.2% (n = 111) brachio-cephalic (BC_AVF), and 6.3% (n = 20) brachio-basilic (BB_AVF). 6, 12, and 24 months follow-up was available in 290 (92.1%), 282 (89.5%), and 259 (82.2%) patients, respectively. Primary patency rates at 6, 12, and 24 months were 39.5%, 34.8%, and 27.2% for RC_AVF, 58.3%, 44.4%, and 27.8% for BC_AVF, and 40.0%, 42.1%, and 22.2% for BB_AVF (p = 0.15). Secondary patency rates at 6, 12, and 24 months were 65.7%, 63.8%, and 59.0% for RC_AVF, 77.7%, 72.0%, and 59.6% for BC_AVF, and 65.0%, 68.4%, and 61.1% for BB_AVF (p = 0.29). Factors associated with lower primary and secondary patency were hemodialysis at time of arteriovenous fistula formation (p = 0.037 and p = 0.024, respectively) and higher Charlson Comorbidity Index (p = 0.036 and p < 0.001, respectively). Previous kidney transplant showed inferior primary patency (p = 0.005); higher age inferior secondary patency (p < 0.001).

DISCUSSION

Vascular access care remains challenging and salvage interventions are often needed to achieve maturation or maintain patency. Strict adherence to standardized outcome reporting in vascular access surgery paints a more realistic picture of arteriovenous fistula patency and enables reliable intercenter comparison.

Ecklonia cava extracts decrease hypertension-related vascular calcification by modulating PGC-1α and SOD2

Vascular calcification (VC) is induced by a decrease in sirtuin 3 (SIRT3) and superoxide dismutase (SOD)2 and increases mitochondrial reactive oxygen species (mtROS), eventually leading to mitochondrial dysfunction and phenotype alterations in vascular smooth muscle cells (VSMCs) into osteoblast-like cells in hypertension. Ecklonia cava extract (ECE) is known to increase peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC-1α) and SOD2. In this study, we evaluated the effect of ECE on decreasing VC by increasing PGC-1α which increased SOD2 activity and decreased mtROS in an in vitro VSMC model of treating serums from Wistar Kyoto (WKY), spontaneous hypertensive rats (SHRs), and ECE-treated SHRs. Furthermore, the decreasing effect of ECE on VC was evaluated with an in vivo SHR model. PGC-1α expression, SIRT3 expression, and SOD2 activity were decreased by the serum from the SHRs and increased by the serum from the ECE-treated SHRs in the VSMCs. PGC-1α silencing eliminated those increases. mtROS generation and mitochondrial DNA (mtDNA) damage increased in the SHRs but decreased with ECE. Mitochondrial fission increased in the SHRs but decreased by ECE. Mitochondrial fusion, mitophagy, and mitochondrial biogenesis were decreased in the SHRs but increased by ECE. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and calcium deposition in the medial layer of the aorta increased in the SHRs but decreased with ECE. Therefore, ECE decreases VC via the upregulation of PGC-1α and SIRT3, which increases SOD2 activity. Activated SOD2 decreases mtDNA damage and mtROS generation, which sequentially decreases NADPH oxidase activity and changes the mitochondrial dynamics, thereby decreasing VC.

Hydrogen sulfide prevents arterial medial calcification in rats with diabetic nephropathy

BACKGROUND

Arterial medial calcification (AMC) is associated with a high incidence of cardiovascular risk in patients with type 2 diabetes and chronic kidney disease. Here, we tested whether hydrogen sulfide (H2S) can prevent AMC in rats with diabetic nephropathy (DN).

METHODS

DN was induced by a single injection of streptozotocin and high-fat diet (45% kcal as fat) containing 0.75% adenine in Sprague-Dawley rats for 8 weeks.

RESULTS

Rats with DN displayed obvious calcification in aorta, and this was significantly alleviated by Sodium Hydrosulfide (NaHS, a H2S donor, 50 μmol/kg/day for 8 weeks) treatment through decreasing calcium and phosphorus content, ALP activity and calcium deposition in aorta. Interestingly, the main endogenous H2S generating enzyme activity and protein expression of cystathionine-γ-lyase (CSE) were largely reduced in the arterial wall of DN rats. Exogenous NaHS treatment restored CSE activity and its expression, inhibited aortic osteogenic transformation by upregulating phenotypic markers of smooth muscle cells SMα-actin and SM22α, and downregulating core binding factor α-1 (Cbfα-1, a key factor for bone formation), protein expressions in rats with DN when compared to the control group. NaHS administration also significantly reduced Stat3 activation, cathepsin S (CAS) activity and TGF-β1 protein level, and improved aortic elastin expression.

CONCLUSIONS

H2S may have a clinical significance for treating AMC in people with DN by reducing Stat3 activation, CAS activity, TGF-β1 level and increasing local elastin level.

Tailoring Hemodialysis Vascular Access in Diabetic Patients

BACKGROUND

The objective of the study was to investigate which kind of native arterious-venous fistula guaranteed the best results in diabetic patients.

METHODS

A retrospective case-control study with prospective follow-up was conducted on all consecutive patients undergoing creation of the first native vascular access (VA) at our Institution between January 2011 and December 2016. Patients were divided into 2 groups: diabetics (group A) and nondiabetics (group B), and results were evaluated in accordance with site chosen for VA creation. Primary outcomes were maturation and primary patency rate. Secondary outcomes were complications, rate of functional fistulas, and mortality.

RESULTS

A total of 410 patients (n 155, 37.8% female; n 255, 62.2% male; mean age 64.21 ± 14.85 years, range 58-78) were divided into 2 nonstatistically different groups (group A: n 170, 41.5% and group B: n 240, 58.5%). Maturation and primary patency were statistically different for antebrachial (P = 0,038 and P = 0.044, respectively), but not for brachial access (P = 1 and P = 0.080, respectively) at 3 years. Hyperflow and steal syndrome rate did not differ between the 2 sites and groups. At a mean follow-up of 42.86 months (range 1-72), 5 patients died. Diabetics demonstrated the higher rate of overall complications at the long-term follow-up.

CONCLUSIONS

Diabetes mellitus plays a detrimental role in maturation and primary patency of antebrachial fistula; however, brachial fistula results do not differ between diabetic and nondiabetic patients. More robust data and longer-term results from randomized studies are needed to affirm brachial fistula as preferential access in diabetic patients.

Selenium-Containing Protein From Selenium-Enriched Spirulina platensis Attenuates High Glucose-Induced Calcification of MOVAS Cells by Inhibiting ROS-Mediated DNA Damage and Regulating MAPK and PI3K/AKT Pathways

Hyperglycemia is the main feature of diabetes and may increase the risk of vascular calcification (VC), which is an independent predictor for cardiovascular and cerebrovascular diseases (CCD). Selenium (Se) may decrease the risk of CCD, and previous studies confirmed that Se-containing protein from Se-enriched Spirulina platensis (Se-SP) exhibited novel antioxidant potential. However, the effect of Se-SP against VC has been not investigated. Herein, the protective effect and underlying mechanism of Se-SP against high glucose-induced calcification in mouse aortic vascular smooth muscle cells (MOVAS) were explored. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) results showed time-dependent uptake of Se-SP in MOVAS cells, which significantly inhibited high glucose-induced abnormal proliferation. Se-SP co-treatment also effectively attenuated high glucose-induced calcification of MOVAS cells, followed by decreased activity and expression of alkaline phosphatase (ALP). Further investigation revealed that Se-SP markedly prevented reactive oxygen species (ROS)-mediated DNA damage in glucose-treated MOVAS cells. ROS inhibition by glutathione (GSH) effectively inhibited high glucose-induced calcification, indicating that Se-SP could act as ROS inhibitor to inhibit high glucose-induced DNA damage and calcification. Moreover, Se-SP dramatically attenuated high glucose-induced dysfunction of mitogen-activated protein kinases (MAPKs) and phosphatidylinositol-3-kinase/AKT (PI3K/AKT) pathways. Se-SP after Se addition achieved enhanced potential in inhibiting high glucose-induced calcification, which validated that Se-SP as a new Se species could be a highly effective treatment for human CCD.

Quantified Vascular Calcification at the Dialysis Access Site: Correlations with the Coronary Artery Calcium Score and Survival Analysis of Access and Cardiovascular Outcomes

Vascular calcification is a major contributor to mortality in end-stage renal disease (ESRD) patients. In this study, we investigated whether there was a correlation between the coronary artery calcium score (CACS) and the vascular calcification score (VCS), and whether higher VCS increased the incidence of interventions and major adverse cardiac and cerebrovascular events (MACCE). ECG-gated CT, including vascular access and the coronary vessel, was taken. CACS and VCS were calculated by the Agatston method. A comparison of CACS and survival analysis according to VCS groups was performed. Using a cutoff of VCS = 500, 77 patients were divided into two groups. The vintage was significantly older in the higher VCS group. The median CACS was higher in the higher VCS group (21 [0, 171] vs. 552 [93, 2430], p < 0.001). The hazard ratio (HR) for interventions and MACCEs in the higher VCS group increased by 3.2 and 2.3, respectively. Additionally, a longer duration of hemodialysis and higher magnesium levels (>2.5 mg/dL) showed lower HRs for interventions (<1). We quantified VCS and found that it was associated with the CACS. Additionally, higher VCS increased the risk of access interventions and MACCE. VCS of the access site may be suggested as a biomarker to predict ESRD patients.

When ESKD complicates the management of diabetes mellitus

Given the increased incidence and prevalence of ESKD (end-stage kidney disease) attributed to diabetes mellitus, it is important to consider the physiological and global sociodemographic factors that give rise to unique challenges in providing excellent care to this population. The individual with diabetes and ESKD faces alterations of glucose homeostasis that require close therapeutic attention, as well as the consideration of safe and effective means of maintaining glycemic control. Implementation of routine monitoring of blood glucose and thoughtful alteration of the individual's hypoglycemic drug regimen must be employed to reduce the risk of neurological, cardiovascular, and diabetes-specific complications that may arise as a result of ESKD. Titration of insulin therapy may become quite challenging, as kidney replacement therapy often significantly impacts insulin requirements. New medications have significantly improved the ability of the clinician to provide effective therapies for the management of diabetes, but have also raised an equal amount of uncertainty with respect to their safety and efficacy in the ESKD population. Additionally, the clinician must consider the challenges related to the delivery of kidney replacement therapy, and how inter-modality differences may impact glycemic control, diabetes, and ESKD-related complications, and issues surrounding dialysis vascular access creation.

Predictors of Primary Functional Maturation of Autogenous Radiocephalic Arteriovenous Fistula in a Cohort of Asian Patients

BACKGROUND

The aim of this study was to investigate the predictors of autogenous radiocephalic arteriovenous fistula (RCAVF) maturation.

METHODS

This was a retrospective analysis of patients undergoing RCAVF creation from June 2013 to December 2018 at a single medical center. Comparison of the variables between the matured and nonmatured group was performed.

RESULTS

A total of 277 patients (men, 173; 62.5%) with a mean age of 56.6 ± 16.9 years underwent primary RCAVF creation during the study period. The mean diameter of the cephalic vein and radial artery were 2.4 ± 0.6 mm (range 1.5 to 4.3 mm) and 2.3 ± 0.5 mm (range 1.5 to 4.0 mm), respectively. Primary functional maturation was achieved in 236 patients (236/277, 85%). There was no statistical significance between the matured and nonmatured group in terms of age (56.4 ± 14.8 vs. 58.1 ± 15.1, respectively; P = 0.498), coronary arterial disease (12% vs. 17%, respectively; P = 0.449), diabetes mellitus (42% vs. 39%, respectively; P = 0.864), smoking (26% vs. 22%, respectively; P = 0.699), or antiplatelet therapy (23% vs. 24%, respectively; P = 0.844). However, female gender (35% vs. 54%, respectively; P = 0.024), peripheral arterial disease (9% vs. 22%, respectively; P = 0.025), and small vein (2.4 ± 0.5 mm vs. 2.0 ± 0.5 mm, respectively; P < 0.01) and artery (2.4 ± 0.5 vs. 2.1 ± 0.4, respectively; P < 0.01) diameter were associated with the failure of maturation. The best cutoff diameter for the cephalic vein and radial artery was 1.85 mm and 2.05 mm, respectively.

CONCLUSIONS

In this cohort of patients undergoing RCAVF creation, vein and artery diameter on preoperative ultrasound mapping was the predictor of functional maturation. Female gender and presence of peripheral arterial disease were associated with failure of maturation.

HIF-1α/PDK4/autophagy pathway protects against advanced glycation end-products induced vascular smooth muscle cell calcification

Osteogenic differentiation of VSMC is one of the main causes of diabetic vascular calcification, and AGEs accumulation accelerates the calcification of VSMCs in diabetic patients. Autophagy has also been found to play an important role in the process of vascular calcification. However, the potential link between AGEs, autophagy and vascular calcification is still unclear and was investigated in this study. Primary VSMCs were isolated from the thoracic aorta of Sprague Dawley rats and cultured with AGEs-BSA to induce osteogenic differentiation. VSMCs calcification was evaluated by measuring the calcium content, RUNX2 protein levels, and by Alizarin red S staining. We demonstrated that treatment of VSMCs with AGE-BSA increased the expression of HIF-1α and PDK4. AGE-BSA treatment increased LC3-II and decreased p62 protein levels. AGE-BSA exposure enhanced autophagic flux determined by mRFP-GFP-LC3 adenovirus, induced co-localization of LC3-II and LAMP-1, and increased the number of autophagasome under TEM. HIF-1α/PDK4 pathway was activated during AGEs-induced autophagy of VSMCs. In addition, autophagy played a protective role during AGE-induced calcification of VSMCs. In conclusion, AGEs enhance autophagy via the HIF-1α/PDK4 signaling pathway, and autophagy helps attenuate AGE-induced calcification of VSMCs.

Hydrogen Sulfide Prevents Elastin Loss and Attenuates Calcification Induced by High Glucose in Smooth Muscle Cells through Suppression of Stat3/Cathepsin S Signaling Pathway

Vascular calcification can be enhanced by hyperglycemia. Elastin loss in tunica media promotes the osteogenic transformation of smooth muscle cells (SMCs) and involves arterial medial calcification (AMC) that is associated with a high incidence of cardiovascular risk in patients with type 2 diabetes. Here, we tested whether hydrogen sulfide (H₂S), an endogenous gaseous mediator, can prevent elastin loss and attenuate calcification induced by high glucose in SMCs. Calcification was induced by high glucose (4500 mg/L) in human aortic SMCs (HASMCs) under the condition of calcifying medium containing 10 mM β-glycerophosphate (β-GP). The experiments showed that NaHS (an H₂S donor, 100 μM) mitigated the calcification of HASMCs treated with high glucose by decreasing calcium and phosphorus levels, calcium deposition and ALP activity and inhibited osteogenic transformation by increasing SMα-actin and SM22α, two phenotypic markers of smooth muscle cells, and decreasing core binding factor α-1 (Cbfα-1), a key factor in bone formation, protein expressions in HASMCs. Moreover, NaHS administration inhibited the activation of Stat3, cathepsin S (CAS) activity and its expression, but increased the level of elastin protein. Pharmacological inhibition or gene silencing Stat3 not only reversed elastin loss, but also attenuated CAS expression. Inhibition of CAS alleviated, while CAS overexpression exacerbated, elastin loss. Interestingly, overexpression of wild type (WT)-Stat3, but not its mutant C259S, elevated CAS protein expression and reduced elastin level. Moreover, NaHS induced S-sulfhydration in WT, but not in the C259S Stat3. These data suggest that H₂S may directly regulate Cys259 residue in Stat3 and then impair its signaling function. Our data indicate that H₂S may attenuate vascular calcification by upregulating elastin level through the inhibition of Stat3/CAS signaling.

Independent association of arteriovenous ratio index on the primary functional maturation of autologous radiocephalic arteriovenous fistula

OBJECTIVE

It has been hypothesized that a novel measurement technique of arteriovenous ratio (AVR) index obtained from inflow (radial artery diameter) to that of outflow (cephalic vein diameter) and its application through the Bernoulli effect has no impact on the primary functional maturation (FM) of autogenous radiocephalic arteriovenous fistula (RCAVF).

METHODS

A prospective consecutive single-center cohort study with intention to treat of 324 patients undergoing RCAVF during a period of 4 years was conducted. Variables of demographics, anatomic factors, laterality, comorbidities, anesthesia type, presence of intraoperative thrill, angle of anastomosis, and AVR index were assessed through univariate and multivariate logistic regression analysis on the end point of FM. The AVR was subjected to three decimal points to ensure maximal accuracy for best sensitivity and 1 - specificity by receiver operating characteristic curve. The χ² (subgroup) analyses were undertaken to investigate the differences in FM incidence within different ranges of AVR. Test of probability (P value) was considered to be significant with P < .05. Effect sizes were reported as odds ratio with their measure of uncertainty at 95% confidence intervals.

RESULTS

Among all variables, the AVR index remained the only independent factor associated with FM (66%; n = 214/324) of RCAVFs (P = .001; 95% confidence interval, 0.08-0.26). AVR of 1 to 1.06 was associated with 100% FM in RCAVFs. Decrease or increase of this index was associated with stepwise reduction in FM of RCAVFs (P < .05).

CONCLUSIONS

The suggested novel measurement technique (AVR index) is an independent predictor of FM in RCAVFs. This study implies that minimal diameter (ie, inflow artery dimeter to outflow cephalic vein diameter) mismatch (AVR, 1-1.06) irrespective of other variables remains crucial for optimal hemodynamics (pressure and velocity) of RACVFs and their primary FM.

Heart disease in chronic kidney disease – review of the mechanisms and the role of dialysis access

Cardiovascular complications are responsible not only for the high mortality, but also the morbidity of end-stage renal disease patients. Cyclic changes of fluid load, together with the altered metabolism, are responsible and are mirrored in many particular parts of the heart. A review of the mechanisms involved is presented and the role of dialysis access is highlighted.