Aortic Arch Calcification Predicts Patency Loss of Arteriovenous Fistula in End-Stage Renal Disease Patients

GDF11 Is a Novel Protective Factor Against Vascular Calcification

ABSTRACT

Vascular calcification (VC) occurs via an active cell-mediated process, which involves osteogenic differentiation, apoptosis, and phenotypic transformation of vascular smooth muscle cells (VSMCs). As a member of the transforming growth factor-β family, growth differentiation factor 11 (GDF11) can inhibit apoptosis and osteogenic differentiation and maintain the stability of atherosclerotic plaques. In this study, coronary artery calcium score (CACS) of participants with GDF11 measurements was measured using computed tomography angiography and was scored according to the Agatston score. β-glycerophosphate (10 mM), dexamethasone (100 nM), and l -ascorbic acid (50 µg/mL) [osteogenic medium (OM)] were used to induce calcification of human aortic smooth muscle cells. We found that CACS was negatively correlated with serum GDF11 levels in patients and GDF11 was a strong predictor of elevated CACS (OR = 0.967, 95% CI: 0.945-0.991; P = 0.006), followed by age (OR = 1.151, 95% CI: 1.029-1.286; P = 0.014), triglycerides (OR = 4.743, 95% CI: 1.170-19.236; P = 0.029), C-reactive protein (OR = 1.230, 95% CI: 1.010-1.498; P = 0.04), and hypertension (OR = 7.264, 95% CI: 1.099-48.002; P = 0.04). Furthermore, exogenous GDF11 inhibited OM-induced calcification by inhibiting osteogenic differentiation, the phenotypic transformation and apoptosis of human aortic smooth muscle cells. Our study demonstrates that GDF11 plays a crucial role in reducing vascular calcification and serves as a potential intervention target to vascular calcification.

An Investigation on the One-year Rate of Arteriovenous Fistula Failure and Its Related Factors in Patients with End-stage Renal Disease; an Experience in Golestan Province of Iran

Background: Aortic arch calcification (AAC) is very common in hemodialysis patients and is associated with cardiovascular events and the incidence of arteriovenous fistula (AVF) failure. In order to predict the prognosis of patients, a study was conducted to determine the annual failure rate of AVF and its related factors. Methods: This cross-sectional study was performed on 145 patients with end-stage renal disease (ESRD) who were AVF candidates, visiting a referral center in Golestan province of Iran. After the insertion of intravenous arterial fistulas, posterior-anterior chest x-rays were captured, and the grafts were classified by a radiologist. Patients were followed for one year, and the rates of fistula failure (FF) and cardiovascular mortality were recorded. Finally, the data were entered into SPSS 19 software and analyzed by the Chi-square test. Results: Of 112 patients followed up for one year, 56.2% were men. During the one-year follow-up period, 5.3% of the patients developed arteriovenous FF, and this event was more common in men, but the difference was not statistically significant. The majority of the AVF candidates had a history of diabetes and hypertension, but no association was found between the one-year FF rate and these two diseases. Nearly 7.7% of the patients had grade III calcification, but no significant relationship was observed between the AAC grade and AVF failure rate. Conclusions: The rate of one-year FF was higher among ESRD patients with a history of chronic kidney diseases. Our results also demonstrated that the mortality rate is higher in patients with a high degree of AAC and patients with medical history (cardiovascular disease and diabetes).

Association of early failure of arteriovenous fistula with mortality in hemodialysis patients

Arteriovenous fistula (AVF) is prone to early dysfunction and relates to poor outcome. However, little is known about the role of early AVF dysfunction as an independent risk factor for death in hemodialysis patients. A retrospective cohort study was performed using data of patients who underwent initial AVF surgery at a single institution. Demographic, clinical, biochemistry and AVF parameters were extracted from the electronic records, and the association between these variables and mortality was analyzed by Cox proportional hazards model. A total of 501 patients on hemodialysis (63.4 ± 12.7 years, 57.3% male) were included, and the median observation period was 3.66 years. In multivariate analysis, early failure of AVF (hazard ratio (95% confidence interval): 1.54 (1.06–2.24); p = 0.023) was associated with overall mortality but not cardiovascular mortality. Other identified predictors of overall mortality included older age, peripheral artery disease (PAD), cardiomegaly, higher white blood cell (WBC) count and corrected calcium level, and lower total cholesterol level, while predictors of cardiovascular mortality included older age, coronary artery disease (CAD), PAD and lower hemoglobin level. In conclusion, patients with early AVF failure were associated with increased risk of overall mortality.

Factors affecting patency of arteriovenous fistula following first percutaneous transluminal angioplasty

BACKGROUND

Percutaneous transluminal angioplasty (PTA) has generally replaced surgical procedures to treat arteriovenous fistula (AVF) dysfunction, but the predictors of post-intervention patency are highly variable. This study aimed to determine predictors of primary patency following PTA of dysfunctional AVF.

MATERIALS AND METHODS

Retrospective analysis of first-time PTA of 307 AVF in 307 patients (171 males, mean age 64.3 ± 12.4 years). Demographic, clinical, anatomical and medication variables were reviewed and subjected to univariate and multivariate Cox regression analysis.

RESULTS

The post-intervention primary patency rates at 6, 12, 24, and 36 months were 76.3%, 58.3%, 43.2%, and 38.2%, respectively. The higher aortic arch calcification (AAC) grade patients were older, had higher incidence of comorbidities and cardiomegaly, and younger AVF age, but their dialysis vintage term was shorter and diastolic blood pressure was lower, and the maximum diameter of balloon angioplasty was mostly ≤ 6 mm, and had lower phosphorus level and less calcium-containing phosphate binder use. In multivariate Cox proportional hazard analysis, the presence of higher AAC grade [hazard ratio (95% confidence interval): (1.46 (1.02-2.09); p = 0.037)] and stenosis at upper arm [1.76 (1.16-2.67); p = 0.008] were associated with shorter post-intervention primary patency.

CONCLUSION

In conclusion, higher AAC grade and anatomic factor related to the location of AVF (upper arm) were the important predictors of AVF dysfunction after PTA. These results could assist in tailoring surveillance programs and performing appropriate interventions for risky AVF.

The Role of Vitamin D in Modulating Mesenchymal Stem Cells and Endothelial Progenitor Cells for Vascular Calcification

Vascular calcification, which involves the deposition of calcifying particles within the arterial wall, is mediated by atherosclerosis, vascular smooth muscle cell osteoblastic changes, adventitial mesenchymal stem cell osteoblastic differentiation, and insufficiency of the calcification inhibitors. Recent observations implied a role for mesenchymal stem cells and endothelial progenitor cells in vascular calcification. Mesenchymal stem cells reside in the bone marrow and the adventitial layer of arteries. Endothelial progenitor cells that originate from the bone marrow are an important mechanism for repairing injured endothelial cells. Mesenchymal stem cells may differentiate osteogenically by inflammation or by specific stimuli, which can activate calcification. However, the bioactive substances secreted from mesenchymal stem cells have been shown to mitigate vascular calcification by suppressing inflammation, bone morphogenetic protein 2, and the Wingless-INT signal. Vitamin D deficiency may contribute to vascular calcification. Vitamin D supplement has been used to modulate the osteoblastic differentiation of mesenchymal stem cells and to lessen vascular injury by stimulating adhesion and migration of endothelial progenitor cells. This narrative review clarifies the role of mesenchymal stem cells and the possible role of vitamin D in the mechanisms of vascular calcification.

Comparison of Solute Clearance, Hospitalization Rate, and Aortic Arch Calcification between Online Hemodiafiltration and High-Flux Hemodialysis: A 6-Year Observational Study

BACKGROUND/AIMS

Studies on the long-term clinical benefits of hemodiafiltration (HDF) and high-flux hemodialysis (HFHD) are very limited. This study aimed to investigate the hospitalization rate and aortic arch calcification (AAC) of these two dialysis modalities over 6 years.

METHODS

Participants who received regular HDF and HFHD in one hospital-facilitated hemodialysis center were prospectively enrolled after matching for age, sex, and diabetes between January 2009 and December 2014. Medical records were reviewed retrospectively on demographics, laboratory variables, calcified scores in aortic arch measured by chest radiography, and rates of hospital admission. Cox proportional hazard regression and linear regression were used to obtain the outcome results.

RESULTS

The HDF and HFHD groups consisted of 108 and 102 participants, respectively. Levels of laboratory variables including small soluble solutes and Kt/V were not statistically different over the 6-year period between the HDF and HFHD groups. Calcified scores of the aortic arch increased over 6 years in both groups. The changes in the mean calcified scores were significant when compared between the two groups (0.44-1.82 in HFHD, 0.79-1.8 in HDF, respectively, p = 0.008). Hospitalization rates were 735 per 1,000 patients in the HDF group and 852 per 1,000 patients in the HFHD group, respectively. No significant difference was observed in frequency and days of hospitalization between HDF and HFHD.

CONCLUSION

Hospitalization rates and AAC were observed to be equal for HDF and HFHD.

Effect of Hydraulic Expansion on Arteriovenous Fistula of Hemodialysis Patients

BACKGROUND

Chronic kidney disease has become a serious public health problem in China. Our study is to explore effect of hydraulic expansion on arteriovenous fistula (AVF) of hemodialysis patients.

METHODS

A total of 190 patients with end-stage renal disease (ESRD) were randomly divided into hydraulic expansion group (n = 117) and conventional surgery group (n = 73). Age, sex, the cause of ESRD, height, weight, body mass index (BMI), blood pressure, and diameter of artery and vein from ultrasonography before surgery from patients were recorded. Doppler ultrasonography of vessel was performed with a 12-MHz scanning probe for vascular measurements. The time of first cannulation was recorded. Primary and secondary patency rates were compared between the two groups.

RESULTS

The mean arterial pressure for this cohort of patients was around 98.12 mm Hg. The mean diameters of artery and vein ready for anastomoses measured by ultrasonography before surgery were 1.96 and 2.04 mm, respectively. Age, weight, BMI, sex ratio, the cause of renal failure, history of catheter insertion, mean arterial pressure, frequency of hemodialysis, blood flow of hemodialysis, and the mode of anastomoses of AVF in conventional surgery group were similar to hydraulic expansion group. There were no differences in stroke volume of radius arterial and venous pressure before dilation between the two groups. The stroke volume of radius artery increased significantly after hydraulic expansion than before dilation and control group. The primary patency rates of AVF in patients with hydraulic expansion were higher significantly than conventional surgery group. The secondary patency rates in conventional surgery group were not different from hydraulic expansion group.

CONCLUSION

Hydraulic expansion showed no difference from conventional surgery in complication after operation, and could decrease the time reliance on catheters and the risk of catheter-related infection, thrombosis, and decrease the related medical care costs.

Emerging Role of Vitamins D and K in Modulating Uremic Vascular Calcification: The Aspect of Passive Calcification

Vascular calcification is a critical complication in patients with chronic kidney disease (CKD) because it is predictive of cardiovascular events and mortality. In addition to the traditional mechanisms associated with endothelial dysfunction and the osteoblastic transformation of vascular smooth muscle cells (VSMCs), the regulation of calcification inhibitors, such as calciprotein particles (CPPs) and matrix vesicles plays a vital role in uremic vascular calcification in CKD patients because of the high prevalence of vitamin K deficiency. Vitamin K governs the gamma-carboxylation of matrix Gla protein (MGP) for inhibiting vascular calcification, and the vitamin D binding protein receptor is related to vitamin K gene expression. For patients with chronic kidney disease, adequate use of vitamin D supplements may play a role in vascular calcification through modulation of the calciprotein particles and matrix vesicles (MVs).

Aortic Arch Calcification as a Predictor of Repeated Arteriovenous Fistula Failure within 1-Year in Hemodialysis Patients

Objectives

The aim of the study was to identify the factors associated with repeated arteriovenous fistula (AVF) failure within 1-year, especially the impact of aortic arch calcification (AAC) on patency of AVF.

Materials and Methods

We retrospectively assessed chest radiography in hemodialysis patients who had undergone initial AVF. The extent of AAC was categorized into four grades (0–3). The association between AAC grade, other clinical variables, and repeated failure of AVF was then analyzed by binary logistic regression analysis.

Results

This study included 284 patients (158 males, mean age 61.7 ± 13.1 years). Patients with higher AAC grade were older, had more frequently diabetes mellitus and cardiovascular disease, had lower diastolic blood pressure, and had higher corrected calcium and lower intact parathyroid hormone levels. In multivariate analysis, the presence of higher AAC grade (odds ratio (95% confidence interval): 2.98 (1.43–6.23); p = 0.004), lower mean corrected calcium (p = 0.017), and mean serum albumin level (p = 0.008) were associated with repeated failure of AVF.

Conclusions

The presence of higher AAC grade, lower mean corrected calcium and mean serum albumin level were independently associated with repeated AVF failure within 1 year in hemodialysis patients.

Intermittent Haemoptysis due to an Aortobronchial Fistula in a Warmblood Mare

A 7-year-old warmblood mare showed sudden onset of mild intermittent haemoptysis. Clinical examination revealed no significant abnormalities. Haematological examination showed mild anaemia, hypoalbuminaemia and neutrophilia. Coagulation tests were normal. Endoscopic examination revealed unilateral pulmonary haemorrhage with blood clots in the bronchi and trachea. Treatment with antibiotics was started and the horse was given stable rest. Two weeks later, the horse was found dead with blood and frothy sputum leaking from the nostrils. Post-mortem examination revealed a large thoracic aortic aneurysm communicating with a pseudoaneurysm that had formed a fistula into a right bronchial branch. Microscopical examination of the aneurysm showed extensive medial fibrosis with prominent degeneration, fragmentation and mineralization of the elastic fibres and deposition of mucoid material in the tunica media. The pseudoaneurysm was lined by collagen bundles admixed with fibroblasts and a small amount of adipose tissue. Aortobronchial fistula is a rare condition in man that is usually associated with primary aortic pathology, most often aneurysms. To the authors' knowledge this is the first case of a fatal aortobronchial fistula in a horse or any other animal species.