Clinical imaging of vascular disease in chronic kidney disease

Analysis of factors influencing vascular calcification in peritoneal dialysis patients and their impact on long-term prognosis

BACKGROUND

This study aims to investigate the influencing factors of vascular calcification in peritoneal dialysis (PD) patients and its relationship with long-term prognosis.

METHODS

This retrospective cohort study included chronic kidney disease patients undergoing peritoneal dialysis at the Peritoneal Dialysis Center of Beijing Luhu Hospital, Capital Medical University, from January 2019 to March 2019. Demographic and clinical laboratory data, including serum sclerostin (SOST), calcium (Ca), phosphate (P), serum albumin (ALB), and intact parathyroid hormone (iPTH) levels, were collected. Abdominal aortic calcification (AAC) was assessed using abdominal lateral X-ray examination to determine the occurrence of vascular calcification, and patients were divided into the AAC group and Non-AAC group based on the results.

RESULTS

A total of 91 patients were included in the study. The AAC group consisted of 46 patients, while the Non-AAC group consisted of 45 patients. The AAC group had significantly older patients compared to the non-AAC group (P < 0.001) and longer dialysis time (P = 0.004). Multivariable logistic regression analysis indicated that risk factors for vascular calcification in PD patients included dialysis time, diabetes, hypertension, and SOST. Kaplan-Meier survival analysis showed that the AAC group had a significantly higher mortality rate than the non-AAC group (χ2 = 35.993, P < 0.001). Multivariable Cox regression analysis revealed that dialysis time, diabetes and AAC were risk factors for all-cause mortality in peritoneal dialysis patients.

CONCLUSION

Longer dialysis time, comorbid diabetes, comorbid hypertension, and SOST are risk factors for vascular calcification in PD patients. Additionally, AAC, longer dialysis time, and comorbid diabetes are associated with increased risk of all-cause mortality in peritoneal dialysis patients.

Early aging and premature vascular aging in chronic kidney disease

Aging is the progressive decline of body functions and a number of chronic conditions can lead to premature aging characterized by frailty, a diseased vasculature, osteoporosis, and muscle wasting. One of the major conditions associated with premature and accelerated aging is chronic kidney disease (CKD), which can also result in early vascular aging and the stiffening of the arteries. Premature vascular aging in CKD patients has been considered as a marker of prognosis of mortality and cardiovascular morbidity and therefore requires further attention. Oxidative stress, inflammation, advanced glycation end products, fructose, and an aberrant gut microbiota can contribute to the development of early aging in CKD patients. There are several key molecular pathways and molecules which play a role in aging and vascular aging including nuclear factor erythroid 2-related factor 2 (Nrf-2), AMP-activated protein kinase (AMPK), sirtuin 1 (SIRT1), and klotho. Potential therapeutic strategies can target these pathways. Future studies are needed to better understand the importance of premature aging and early vascular aging and to develop therapeutic alternatives for these conditions.

Hypoxia-inducible factor signaling in vascular calcification in chronic kidney disease patients

Chronic kidney disease (CKD) affects approximately 15% of the adult population in high-income countries and is associated with significant comorbidities, including increased vascular calcifications which is associated with a higher risk for cardiovascular events. Even though the underlying pathophysiology is unclear, hypoxia-inducible factor (HIF) signaling appears to play a central role in inflammation, angiogenesis, fibrosis, cellular proliferation, apoptosis and vascular calcifications which is influenced by multiple variables such as iron deficiency anemia, serum phosphorus and calcium levels, fibroblast growth factor-23 (FGF-23) and Klotho. Along with the growing understanding of the pathology, potential therapeutic alternatives have emerged including HIF stabilizers and SGLT-2 inhibitors. The aim of this review is to discuss the role of HIF signaling in the pathophysiology of vascular calcification in CKD patients and to identify potential therapeutic approaches.

Uremic Vascular Calcification: The Pathogenic Roles and Gastrointestinal Decontamination of Uremic Toxins

Uremic vascular calcification (VC) commonly occurs during advanced chronic kidney disease (CKD) and significantly increases cardiovascular morbidity and mortality. Uremic toxins are integral within VC pathogenesis, as they exhibit adverse vascular influences ranging from atherosclerosis, vascular inflammation, to VC. Experimental removal of these toxins, including small molecular (phosphate, trimethylamine-N-oxide), large molecular (fibroblast growth factor-23, cytokines), and protein-bound ones (indoxyl sulfate, p-cresyl sulfate), ameliorates VC. As most uremic toxins share a gut origin, interventions through gastrointestinal tract are expected to demonstrate particular efficacy. The “gastrointestinal decontamination” through the removal of toxin in situ or impediment of toxin absorption within the gastrointestinal tract is a practical and potential strategy to reduce uremic toxins. First and foremost, the modulation of gut microbiota through optimizing dietary composition, the use of prebiotics or probiotics, can be implemented. Other promising strategies such as reducing calcium load, minimizing intestinal phosphate absorption through the optimization of phosphate binders and the inhibition of gut luminal phosphate transporters, the administration of magnesium, and the use of oral toxin adsorbent for protein-bound uremic toxins may potentially counteract uremic VC. Novel agents such as tenapanor have been actively tested in clinical trials for their potential vascular benefits. Further advanced studies are still warranted to validate the beneficial effects of gastrointestinal decontamination in the retardation and treatment of uremic VC.

Complications of metabolic acidosis and alkalinizing therapy in chronic kidney disease patients: a clinician-directed organ-specific primer

Chronic kidney disease is prevalent, affecting more than one in ten adults. In this population, metabolic acidosis is considered a key underlying pathophysiological feature, tying together bone mineral disorders, sarcopenia, insulin resistance, vascular calcification, pro-inflammatory and pro-thrombotic states. This review aims to address the paucity of literature on alkalinizing agents, a promising treatment option that has known adverse effects.

A journey from microenvironment to macroenvironment: the role of metaflammation and epigenetic changes in cardiorenal disease

Chronic non-communicable diseases have become a pandemic public problem in the 21st century, causing enormous burden on the economy, health and quality of life of societies. The role of a chronic inflammatory state in the pathogenesis of chronic disease has been more comprehensively recognized by recent findings. The new paradigm ‘metaflammation’ focuses on metabolism-induced (high fat or fructose-based diet or excessive calorie intake) chronic inflammation. There is a close correlation between the increased incidence of chronic kidney disease (CKD) and chronic heart failure with both increased inflammatory marker levels and western-type diet. In this review we describe the concept of metaflammation, its role in the development of CKD and chronic heart disease, the molecular and signalling pathways involved and the therapeutic consequences.

Can Incidental Vascular Calcifications at Mammography be Used as a Screening Biomarker for Heart and Kidney Disease?

Mammography is a screening test with extensive international application and financial infrastructure promoting accessibility and affordability. Designed specifically to detect microcalcifications, mammography is powered to detect calcifications in vessel walls. Breast arterial calcifications (BAC) are one of the most common incidental findings documented by mammography. This review considers the literature regarding BAC in relation to cardiovascular disease (CVD) and its risk factors. The aim is to assess the possibility of using BAC as an early surrogate imaging biomarker of CVD.

Abdominal aorta and pelvic artery calcifications on plain radiographs may predict mortality in chronic kidney disease, hemodialysis and renal transplantation

PURPOSE

Vascular calcification is common in chronic kidney disease (CKD) and predicts poor patient outcomes. While computed tomography is the gold standard for evaluation of vascular calcification, plain radiograph offers a simpler and less costly alternative. The calcification of abdominal aorta, iliac and femoral arteries has been evaluated by plain radiograph, but the data on their outcome predictabilities are still limited. The present study investigated the role of abdominal aortic calcification (AAC) and pelvic arterial calcification (PAC) in predicting overall morality in non-dialysis CKD stages 2-5 (CKD 2-5), maintenance hemodialysis (HD) and long-term kidney transplant (KT) patients.

METHODS

Four hundred and nineteen patients were included. Lateral abdominal and pelvic radiographs were obtained. The degree of AAC and PAC was evaluated according to the methods described previously by Kaupplia et al. and Adragao et al. Patients were followed prospectively for 5 years.

RESULTS

AAC and PAC scores correlated well with the correlation coefficients of 0.442 for CKD 2-5, 0.438 for HD and 0.586 for KT (p < 0.001). Patients with AAC score > 6 or PAC score > 1 were older, showed higher prevalence of DM and had higher serum phosphate and PTH but lower serum albumin and eGFR. A more severe degree of AAC was associated with an increase in KT duration, whereas a more severe degree of PAC was associated with worsening kidney function and prolonged dialysis vintage. Kaplan-Meier survival curves revealed AAC score > 6 as a significant predictor of all-cause mortality in CKD 2-5 but not in HD or KT, whereas PAC score > 1 was a significant predictor of all-cause mortality in all three populations. After adjusting for age, the predictability of AAC was lost, whereas PAC remained an independent predictor of mortality in all three populations. Adjustments for cardiovascular and CKD risk factors including age, gender, BMI, DM, serum albumin, calcium and phosphate attenuated the predictability of PAC in HD but not in CKD 2-5 or KT patients.

CONCLUSION

PAC was better than AAC in predicting mortality in CKD, HD and KT patients.

Prevalence of abdominal artery calcification in dialysis patients with end-stage renal disease: a systematic review and meta-analysis

PURPOSE

To systematically determine the prevalence of abdominal artery calcification (AAC) in dialysis patients with end-stage renal disease (ESRD) and identify reasons for heterogeneity.

METHODS

We searched PubMed, EMBASE, and Web of Science from database inception to March 2017. Cross-sectional or cohort (only used baseline data) studies reporting estimates of AAC prevalence in dialysis adult patients with ESRD were included. We performed a random-effects meta-analysis to generate pooled prevalence estimates. Subgroup analyses were used to compare differences within categorical variables (geographic region, AAC detection instruments, dialysis methods, study design, and sample size), and meta-regression analyses to assess the impact of continuous variables (participants' age, duration of dialysis, and male proportion).

RESULTS

A total of 44 studies with 9883 dialysis patients were included. The pooled prevalence for AAC was 68.5% (95% CI 63-73.9%). Subgroup analyses suggested that AAC prevalence varied significantly by geographical region and AAC detection instruments, not by dialysis methods, study design and sample size. Meta-regression analysis suggested that positive correlations were found between AAC prevalence and the age of participants as well as the male proportion (r = 1.01477, P = 0.002 and r = 2.034413, P = 0.01, respectively), but not with the duration of dialysis (P = 0.576).

CONCLUSION

The pooled and nearest estimate of AAC prevalence among dialysis patients was as high as 65%. Geographical region, AAC detection instruments, age of participants, and male proportion potentially lead to the high variance of the reported prevalence. Considering the high AAC prevalence, effective treatment for preventing vascular calcification in these patients is badly needed.

Renal denervation using carbon dioxide renal angiography in patients with uncontrolled hypertension and moderate to severe chronic kidney disease

Background

Chronic kidney disease (CKD) is the most common cause of secondary hypertension. More than half of the patients have uncontrolled hypertension (≥140/90 mmHg on three or more antihypertensive agents at optimum doses). Renal sympathetic denervation (RSDN) has been shown to reduce blood pressure (BP) in patients with resistant hypertension. Although patients with CKD have high sympathetic drive, all major clinical trials have excluded patients with estimated glomerular filtration rates (eGFRs) <45 mL/min/1.73m² for risk of contrast-induced nephropathy.

Methods

In this pilot study, carbon dioxide (CO₂) was used as the sole contrast agent to carry out renal angiography and RSDN in patients with moderate to severe CKD (eGFR 15–44 mL/min/1.73m²) and uncontrolled hypertension.

Results

Eleven patients (eight males) underwent RSDN. The median age was 57 years [interquartile range (IQR) 49–66]. The median number of antihypertensives being taken at baseline was 4 (IQR 3–4). No statistically significant difference was observed in serum creatinine in the serial follow-ups until at 6 months[median difference 0.25 mg/dL (IQR 0.09–0.53); P = 0.008]. There was a non-significant reduction in median clinic BP from baseline to 6 months [−14 mmHg (IQR −24–5)] and a significant increase in daytime ambulatory systolic BP [7 mmHg (IQR −2–12); P= 0.045]. A trend towards a serial reduction in albuminuria was observed. Procedure-related complications included a groin haematoma (n = 1) and reported flank (n = 1) and groin pain (n = 1).

Conclusions

This pilot study shows that CO₂ renal angiography can be used to perform RSDN in patients with significant renal impairment and may lead to associated improvements in clinic BP and albuminuria.