Diastolic Dysfunction, an Underestimated New Challenge in Dialysis

Chronic kidney disease and left ventricular diastolic dysfunction (CKD-LVDD) alter cardiac expression of mitochondria-related genes in swine

Cardiovascular disease and heart failure doubles in patients with chronic kidney disease (CKD), but the underlying mechanisms remain obscure. Mitochondria are central to maintaining cellular respiration and modulating cardiomyocyte function. We took advantage of our novel swine model of CKD and left ventricular diastolic dysfunction (CKD-LVDD) to investigate the expression of mitochondria-related genes and potential mechanisms regulating their expression. CKD-LVDD and normal control pigs (n=6/group, 3 males/3 females) were studied for 14 weeks. Renal and cardiac hemodynamics were quantified by multidetector-CT, echocardiography, and pressure-volume loop studies, respectively. Mitochondrial morphology (electron microscopy) and function (Oroboros) were assessed ex vivo. In randomly selected pigs (n=3/group), cardiac mRNA-, MeDIP-, and miRNA-sequencing (seq) were performed to identify mitochondria-related genes and study their pre- and post -transcriptional regulation. CKD-LVDD exhibited cardiac mitochondrial structural abnormalities and elevated mitochondrial H2O2 emission but preserved mitochondrial function. Cardiac mRNA-seq identified 862 mitochondria-related genes, of which 69 were upregulated and 33 downregulated (fold-change ≥2, false discovery rate≤0.05). Functional analysis showed that upregulated genes were primarily implicated in processes associated with oxidative stress, whereas those downregulated mainly participated in respiration and ATP synthesis. Integrated mRNA/miRNA/MeDIP-seq analysis showed that upregulated genes were modulated predominantly by miRNAs, whereas those downregulated were by miRNA and epigenetic mechanisms. CKD-LVDD alters cardiac expression of mitochondria-related genes, associated with mitochondrial structural damage but preserved respiratory function, possibly reflecting intrinsic compensatory mechanisms. Our findings may guide the development of early interventions at stages of cardiac dysfunction in which mitochondrial injury could be prevented, and the development of LVDD ameliorated.

Renal and cardiovascular prognostic significance of echocardiographic early diastolic mitral annular velocity in IgA nephropathy

In chronic kidney disease (CKD), as in IgA nephropathy (IgAN), cardiovascular (CV) mortality and morbidity are many times higher than in the general population, and diastolic dysfunction (LVDD) has prognostic significance as well. Tissue Doppler Echocardiography (TDI) is another method for measuring myocardial contractility and determining diastolic dysfunction. 79 IgAN patients (age 46 ± 11 years) with CKD stages 1-3 were investigated and followed for 70 ± 28.7 months. Doppler echocardiography was used to measure the E (early) and A (late) waves, as well as the E wave deceleration time (EDT) during mitral inflow. TDI was used to measure early (Ea) and late (Aa) diastolic velocities (lateral and septal basal wall fragment average). From these, we calculated the E/Ea and Ea/Aa ratios. The primary combined endpoints were total mortality, major CV events, and end-stage renal disease, and the secondary endpoints were cardiovascular or renal (eGFR decreased below 15 ml/min/1.73 m2 or renal replacement therapy was started). Patients with decreased Ea (< 13 cm/s) had significantly more endpoints (20/42 vs. 3/37; p = 0.001) than patients with higher Ea (≥ 13 cm/s). The secondary renal endpoints were also significantly higher (p = 0.004). In a multivariate model, the eGFR showed independent correlation with the E/A ratio (r = 0.466; p < 0.01), EDT (r = - 0.270; p < 0.01), Ea/Aa ratio (r = 0.455; p < 0.01), and decreased Ea (r = 0.544; p < 0.01). Independent factors influencing Ea were only EDT by uni- and multivariate regression but age and albuminuria by logistic regression. Decreased Ea measured by TDI seems to be an eligible factor to predict the prognosis of IgA nephropathy. The decreased Ea may be a helpful parameter to identify high-risk CKD patients.

The moderating effect of fluid overload on the relationship between the augmentation index and left ventricular diastolic function in patients with CKD

Increased vascular stiffness, fluid overload, and left ventricular diastolic dysfunction (LVDD) are common in patients with chronic kidney disease (CKD). We investigated the potential moderating effect of volume status in the relationship between arterial stiffness and left ventricular (LV) diastolic function in non-dialysis patients with stage 5 CKD. The radial augmentation index at a heart rate of 75 beats/min (rAIx75), overhydration/extracellular water (OH/ECW), and E/e´ ratio were concurrently measured in 152 consecutive patients. Each of these parameters reflects the status of vascular stiffness, fluid balance, and LV diastolic function, respectively. Hierarchical regression analysis demonstrated a significant interaction effect of OH/ECW for all patients (P = 0.015), even after controlling for confounders. In separate analyses, this interaction effect was particularly significant in women (P = 0.010), whereas its significance in patients with diabetes was marginally significant (P = 0.062). Our study suggested that fluid overload could be one of the more aggravating factors of LVDD in patients with CKD who have increased arterial stiffness. Therefore, it is advisable to conduct simultaneous assessments of vascular stiffness, fluid balance, and LV function, particularly in the specific groups mentioned earlier. Our results may serve as evidence applicable to patients with chronic heart failure.

Relationship between arterial stiffness, left ventricular diastolic function, and renal function in chronic kidney disease

AIM

In chronic kidney disease, IgA nephropathy, and left ventricular diastolic dysfunction have prognostic significance as well. However, the relationship between diastolic dysfunction, arterial stiffness, and renal function has not been fully elucidated.

METHODS

79 IgA nephropathy patients (aged 46 ± 11 years) and 50 controls were investigated. Tissue Doppler imaging was used to measure early (Ea) and late (Aa) diastolic velocities. Arterial stiffness was measured by a photoplethysmographic (stiffness index (SI)) and an oscillometric method (aortic pulse wave velocity (PWVao)).

RESULTS

We compared the IgAN patients to a similar cardiovascular risk group with a preserved eGFR. A strong correlation was found between Ea/Aa and SI (p < 0.001), also with PWVao (p < 0.001), just in IgAN, and with eGFR (p < 0.001) in both groups. IgAN patients were divided into groups CKD1-2 vs. CKD3-5. In the CKD 3-5 group, the incidence of diastolic dysfunction increased significantly: 39% vs. 72% (p = 0.003). Left ventricle rigidity (LVR) was calculated, which showed a close correlation with SI (p = 0.009) and eGFR (p = 0.038). By linear regression analysis, the independent predictors of SI were age, E/A, and E/Ea; SI was the predictor of LVR; and E/A and hypertension were the predictors of eGFR.

CONCLUSION

In chronic kidney disease, increased cardiac rigidity and vascular stiffness coexist with decreased renal function, which is directly connected to diastolic dysfunction and vascular stiffness. On the basis of comparing the CKD group to the control group, vascular alterations in very early CKD can be identified.

Comparing Left Ventricular Diastolic Function between Peritoneal Dialysis and Non-Dialysis Patients with Stage 5 Chronic Kidney Disease: A Propensity Score-Matched Analysis

Patients with chronic kidney disease (CKD) have a high incidence of left ventricular diastolic dysfunction (LVDD), which increases the risk of heart failure and mortality. We assessed fluid overload as an independent risk factor for LVDD in patients with decreased kidney function and compared its impact on the E/e' ratio as a parameter for assessing left ventricular diastolic functions between patients undergoing continuous ambulatory peritoneal dialysis (CAPD) and those with non-dialysis CKD stage 5 (CKD5) using propensity score matching (PSM). After PSM, 222 patients (CAPD, n = 111; CKD5, n = 111) were included. Fluid balance was assessed using bio-impedance spectroscopy and LVDD was determined by echocardiography based on an E/e' ratio of >15. The CKD5 group had a significantly higher E/e' ratio (p = 0.002), while fluid overload (OH/ECW) did not differ significantly between the groups. In the CAPD group, there were no significant differences in OH/ECW between patients with and without LVDD (p = 0.517). However, in the CKD5 group, patients with LVDD showed a significantly higher OH/ECW (p = 0.001). In a regression analysis investigating factors associated with the E/e' ratio, OH/ECW was not significantly associated with the E/e' ratio in the CAPD group (p = 0.087), but in the CKD5 group, it was independently correlated (p = 0.047). The factors closely associated with LVDD varied depending on dialysis dependence. While fluid overload independently influenced LVDD in non-dialysis patients, it was not statistically significant in patients with CAPD. Early assessment and management of volume status are crucial in addressing LVDD in patients with advanced-stage CKD.

Prevention of Intradialytic Hypotension in Hemodialysis Patients: Current Challenges and Future Prospects

Intradialytic hypotension, defined as rapid decrease in systolic blood pressure of greater than or equal to 20 mmHg or in mean arterial pressure of greater than or equal to 10 mmHg that results in end-organ ischemia and requires countermeasures such as ultrafiltration reduction or saline infusion to increase blood pressure to improve patient's symptoms, is a known complication of hemodialysis and is associated with several potential adverse outcomes. Its pathogenesis is complex and involves both patient-related factors such as age and comorbidities, as well as factors related to the dialysis prescription itself. Key factors include the need for volume removal during hemodialysis and a suboptimal vascular response which compromises the ability to compensate for acute intravascular volume loss. Inadequate vascular refill, incorrect assessment or unaccounted changes of target weight, acute illnesses and medication interference are further potential contributors. Intradialytic hypotension can lead to compromised tissue perfusion and end-organ damage, both acutely and over time, resulting in repetitive injuries. To address these problems, a careful assessment of subjective symptoms, minimizing interdialytic weight gains, individualizing dialysis prescription and adjusting the dialysis procedure based on patients' risk factors can mitigate negative outcomes.

Why is Intradialytic Hypotension the Commonest Complication of Outpatient Dialysis Treatments?

Intradialytic hypotension (IDH) is the most frequent complication of hemodialysis (HD) treatments with a frequency of 10% to 12% for patients with chronic kidney disease attending for outpatient treatments and is associated with both temporary ischemic stress to vital organs, including the heart and brain, and increased patient mortality. Although there have been many different definitions of IDH over the years, an absolute nadir systolic blood pressure (SBP) has the strongest association with patient outcomes. The unifying pathophysiology is one of reduced effective blood volume, resulting in lower plasma tonicity, and if this cannot be adequately compensated for by activation of neurohumeral systems, then arteriolar tone and blood pressure fall. The risk factors for developing IDH are numerous, ranging from patient-related factors, including age and comorbidity with reduced cardiac reserve, to patient compliance with dietary and lifestyle advice, to reactions with the extracorporeal circuit and medications, choice of dialysate composition and temperature, setting of postdialysis target weight, ultrafiltration rate, and profiling. Advances in dialysis machine technology by providing real time estimates of the effective circulating volume and adjusting dialysate composition to maintain vascular tonicity are being developed, but currently require more sophisticated biofeedback loops to be clinically effective in preventing IDH. While awaiting advances in artificial intelligence, the clinician continues to rely on patient education to limit interdialytic weight gains, frequent assessment of the postdialysis target weight, adjusting dialysate composition and temperature, introducing convective therapies to increase thermal losses, and altering dialysis session duration and frequency to reduce ultrafiltration rate requirements.

Alpha-klotho and peritoneal membrane status: A hypothesis generating study

BACKGROUND

Long-term success of peritoneal dialysis relies on the integrity of the peritoneal membrane. This proof-of-concept study addressed the hypothesis that fibrosis is already present in the membrane at pre-dialysis and that the membrane status is related to the individual's uraemic fingerprint.

METHODS

A clinical-mechanistic, transversal, single-centre study was conducted. Pre-dialysis peritoneal biopsies were scored considering the submesothelial compact zone thickness (STM), vasculopathy and inflammation. We investigated if the membrane status could be inferred from a panel of proteins (α-Klotho, Galectin-3, FGF21, FGF23, Tweak, TNFα and hsPCR) in blood.

RESULTS

A total 58 incident patients aged 56 ± 15 years old were included, 31% female, 55% hypertension, 29% diabetic and 24% obese. Person-to-person STM was found to be highly variable and 38% of patients were fibrosis positive. Both α-Klotho (Spearman r = -.7491, p < 0.001) and FGF21 (Spearman r = -.5102, p < 0.001) were negatively associated with STM. α-Klotho, but not FGF21, was able to discriminate fibrosis from nonfibrosis with/without inflammation and vasculopathy. PLS models identified α-Klotho as the protein most relevant for fibrosis. α-Klotho was independently associated with fibrosis of the peritoneal membrane (OR = .991 (.896-.997), p = 0.002).

CONCLUSION

Before the start of dialysis in incident patients, some patients already present fibrosis of the peritoneal membrane and other patients do not. Our findings suggest that α-Klotho may be implicated in fibrosis of the peritoneal membrane.

Cardiac epigenetic changes in VEGF signaling genes associate with myocardial microvascular rarefaction in experimental chronic kidney disease

Chronic kidney disease (CKD) is common in patients with heart failure and often results in left ventricular diastolic dysfunction (LVDD). However, the mechanisms responsible for cardiac damage in CKD-LVDD remain to be elucidated. Epigenetic alterations may impose long-lasting effects on cellular transcription and function, but their exact role in CKD-LVDD is unknown. We investigate whether changes in cardiac site-specific DNA methylation profiles might be implicated in cardiac abnormalities in CKD-LVDD. CKD-LVDD and normal control pigs (n = 6 each) were studied for 14 wk. Renal and cardiac hemodynamics were quantified by multidetector CT and echocardiography. In randomly selected pigs (n = 3/group), cardiac site-specific 5-methylcytosine (5mC) immunoprecipitation (MeDIP)- and mRNA-sequencing (seq) were performed, followed by integrated (MeDiP-seq/mRNA-seq analysis), and confirmatory ex vivo studies. MeDIP-seq analysis revealed 261 genes with higher (fold change > 1.4; P < 0.05) and 162 genes with lower (fold change < 0.7; P < 0.05) 5mC levels in CKD-LVDD versus normal pigs, which were primarily implicated in vascular endothelial growth factor (VEGF)-related signaling and angiogenesis. Integrated MeDiP-seq/mRNA-seq analysis identified a select group of VEGF-related genes in which 5mC levels were higher, but mRNA expression was lower in CKD-LVDD versus normal pigs. Cardiac VEGF signaling gene and VEGF protein expression were blunted in CKD-LVDD compared with controls and were associated with decreased subendocardial microvascular density. Cardiac epigenetic changes in VEGF-related genes are associated with impaired angiogenesis and cardiac microvascular rarefaction in swine CKD-LVDD. These observations may assist in developing novel therapies to ameliorate cardiac damage in CKD-LVDD.NEW & NOTEWORTHY Chronic kidney disease (CKD) often leads to left ventricular diastolic dysfunction (LVDD) and heart failure. Using a novel translational swine model of CKD-LVDD, we characterize the cardiac epigenetic landscape, identifying site-specific 5-methylcytosine changes in vascular endothelial growth factor (VEGF)-related genes associated with impaired angiogenesis and cardiac microvascular rarefaction. These observations shed light on the mechanisms of cardiac microvascular damage in CKD-LVDD and may assist in developing novel therapies for these patients.

The significance of volume overload in the development of pulmonary arterial hypertension in continuous ambulatory peritoneal dialysis patients

INTRODUCTION

The underlying pathophysiology of pulmonary arterial hypertension (PAH) is multifactorial; however, the significance of chronic volume overload and its subsequent effects on cardiac function must be studied thoroughly. The main objective of this study was to determine the predictive parameters of PAH in patients undergoing continuous ambulatory peritoneal dialysis (CAPD) using transthoracic echocardiography (TTE) and bioimpedance analysis (BIA).

METHODS

In this cross-sectional study, 43 eligible CAPD patients were chosen. The patients were examined by TTE and BIA before the morning dialysis session, and baseline patient characteristics, echocardiography, and BIA parameters were recorded.

RESULTS

Sixteen (37.2%) patients were diagnosed with PAH. Patients with PAH had significantly greater left atrial diameter (LAD), left ventricular mass index (LVMI), and higher grades of diastolic dysfunction (DDF). Systolic pulmonary artery pressure (sPAP) correlated with LAD (p < 0.001, r = 0.566), interventricular septal diameter (IVSD) (p = 0.004, r = 0.425), LVMI (p = 0.030, r = 0.323), and extracellular water/total body water (ECW/TBW) ratio (p = 0.002, r = 0.458).

CONCLUSION

Two volume status-related parameters including ECW/TBW ratio and inferior vena cava (IVC) expiratory diameter, and cardiac-related TTE findings such as LAD and DDF were predictors of sPAP in CAPD patients.

Cardiac micro-RNA and transcriptomic profile of a novel swine model of chronic kidney disease and left ventricular diastolic dysfunction

Chronic kidney disease (CKD) is an independent risk factor for the development of heart failure, but the underlying mechanisms remain unknown. Using a novel translational swine model of CKD and cardiac dysfunction, we hypothesize that CKD alters the cardiac miRNA and transcriptomic profile that associate with cardiac remodeling and metabolic processes implicated in the development of left ventricular diastolic dysfunction (CKD-LVDD). CKD-LVDD and normal control pigs (n = 6 each) were studied for 14 wk. Renal and cardiac hemodynamics were quantified by multidetector CT and echocardiography. In randomly selected pigs (n = 3/group), cardiac miRNA- and mRNA-sequencing (seq) was performed, validated (qPCR), and followed by confirmatory ex vivo studies. Differential expression analysis identified nine miRNAs and 125 mRNAs upregulated and 17 miRNAs and 172 mRNAs downregulated [fold-change ≥ 2, and false discovery rate (FDR) ≤ 0.05] in CKD-LVDD versus normal controls. Integrated miRNA-/mRNA-seq analysis identified 71 overlappings downregulated mRNA targets of miRNAs upregulated, and 39 overlappings upregulated mRNA targets of miRNAs downregulated in CKD-LVDD versus controls. Functional analysis showed that these genes were primarily implicated in processes associated with cardiac remodeling, including ubiquitination, ATP and fatty acid synthesis, and extracellular matrix remodeling. In agreement, hearts of CKD-LVDD pigs exhibited abnormal diastolic relaxation, mitochondrial injury, moderate LV fibrosis, and myocardial lipid accumulation. Our work comprehensively characterizes the cardiac micro-RNA and transcriptomic profile of a translational model of CKD-LVDD. Our data may set the foundation for new targeted studies to further elucidate LVDD pathophysiology and assist to develop therapeutic interventions.NEW & NOTEWORTHY Chronic kidney disease (CKD) is a progressive disorder in which more than 50% of deaths are attributed to cardiovascular disease. Using a swine model of CKD that develops left ventricular dysfunction (CKD-LVDD), we characterize the cardiac micro-RNA and transcriptomic profile, identifying dysregulated genes associated with cardiac remodeling and fatty acid metabolism that might be post-transcriptionally regulated early in the disease. These findings pinpointed pathological pathways that may open new avenues toward therapeutic research to reduce cardiovascular morbidity in CKD.

Renal mitochondrial injury in the pathogenesis of CKD: mtDNA and mitomiRs

Chronic kidney disease (CKD) is a public health concern that affects over 200 million people worldwide and is associated with a tremendous economic burden. Therefore, deciphering the mechanisms underpinning CKD is crucial to decelerate its progression towards end-stage renal disease (ESRD). Renal tubular cells are populated with a high number of mitochondria, which produce cellular energy and modulate several important cellular processes, including generation of reactive oxygen species (ROS), calcium homeostasis, proliferation, and apoptosis. Over the past few years, increasing evidence has implicated renal mitochondrial damage in the pathogenesis of common etiologies of CKD, such as diabetes, hypertension, metabolic syndrome (MetS), chronic renal ischemia, and polycystic kidney disease (PKD). However, most compelling evidence is based on preclinical studies because renal biopsies are not routinely performed in many patients with CKD. Previous studies have shown that urinary mitochondrial DNA (mtDNA) copy numbers may serve as non-invasive biomarkers of renal mitochondrial dysfunction. Emerging data also suggest that CKD is associated with altered expression of mitochondria-related microRNAs (mitomiRs), which localize in mitochondria and regulate the expression of mtDNA and nucleus-encoded mitochondrial genes. This review summarizes relevant evidence regarding the involvement of renal mitochondrial injury and dysfunction in frequent forms of CKD. We further provide an overview of non-invasive biomarkers and potential mechanisms of renal mitochondrial damage, especially focusing on mtDNA and mitomiRs.

Multitargeted interventions to reduce dialysis-induced systemic stress

Hemodialysis (HD) is a life-sustaining therapy as well as an intermittent and repetitive stress condition for the patient. In ridding the blood of unwanted substances and excess fluid from the blood, the extracorporeal procedure simultaneously induces persistent physiological changes that adversely affect several organs. Dialysis patients experience this systemic stress condition usually thrice weekly and sometimes more frequently depending on the treatment schedule. Dialysis-induced systemic stress results from multifactorial components that include treatment schedule (i.e. modality, treatment time), hemodynamic management (i.e. ultrafiltration, weight loss), intensity of solute fluxes, osmotic and electrolytic shifts and interaction of blood with components of the extracorporeal circuit. Intradialytic morbidity (i.e. hypovolemia, intradialytic hypotension, hypoxia) is the clinical expression of this systemic stress that may act as a disease modifier, resulting in multiorgan injury and long-term morbidity. Thus, while lifesaving, HD exposes the patient to several systemic stressors, both hemodynamic and non-hemodynamic in origin. In addition, a combination of cardiocirculatory stress, greatly conditioned by the switch from hypervolemia to hypovolemia, hypoxemia and electrolyte changes may create pro-arrhythmogenic conditions. Moreover, contact of blood with components of the extracorporeal circuit directly activate circulating cells (i.e. macrophages-monocytes or platelets) and protein systems (i.e. coagulation, complement, contact phase kallikrein-kinin system), leading to induction of pro-inflammatory cytokines and resulting in chronic low-grade inflammation, further contributing to poor outcomes. The multifactorial, repetitive HD-induced stress that globally reduces tissue perfusion and oxygenation could have deleterious long-term consequences on the functionality of vital organs such as heart, brain, liver and kidney. In this article, we summarize the multisystemic pathophysiological consequences of the main circulatory stress factors. Strategies to mitigate their effects to provide more cardioprotective and personalized dialytic therapies are proposed to reduce the systemic burden of HD.

Intrarenal modulation of NF-κB activity attenuates cardiac injury in a swine model of CKD: a renal-cardio axis

Patients with chronic kidney disease (CKD) have a high cardiovascular mortality. CKD and heart failure (HF) coexist in up to 50% of patients, and both associate with inflammation. We aimed to define the cardiac phenotype of a novel swine model of CKD and test the hypothesis that inflammation of renal origin propels the development of precursors of HF in CKD. CKD was induced in 14 pigs, which were followed for 14 wk. Renal (multidetector computed tomography) and cardiac (echocardiography) hemodynamics were quantified before and 8 wk after single intrarenal administration of placebo or a biopolymer-fused peptide inhibitor of NF-κB that blocks NF-κB activity and decreases inflammatory activity (SynB1-ELP-p50i). Blood was collected to quantify cytokines (TNF-α, monocyte chemoattractant protein-1, and interleukins), markers of inflammation (C-reactive protein), and biomarkers of HF (atrial and brain natriuretic peptides). Pigs were then euthanized, and kidneys and hearts were studied ex vivo. Normal pigs were used as time-matched controls. Renal dysfunction in CKD was accompanied by cardiac hypertrophy and fibrosis, diastolic dysfunction, increased renal and cardiac expression of TNF-α, monocyte chemoattractant protein-1, and interleukins, canonical and noncanonical mediators of NF-κB signaling, circulating inflammatory factors, and biomarkers of HF. Notably, most of these changes were improved after intrarenal SynB1-SynB1-ELP-p50i, although cardiac inflammatory signaling remained unaltered. The translational traits of this model support its use as a platform to test novel technologies to protect the kidney and heart in CKD. A targeted inhibition of renal NF-κB signaling improves renal and cardiac function, suggesting an inflammatory renal-cardio axis underlying early HF pathophysiology in CKD.NEW & NOTEWORTHY Chronic kidney disease (CKD) is a progressive disorder with high cardiovascular morbidity and mortality. This work supports the role of inflammatory cytokines of renal origin in renal-cardio pathophysiology in CKD and that the heart may be a target. Furthermore, it supports the feasibility of a new strategy in a translational fashion, using targeted inhibition of renal NF-κB signaling to offset the development of cardiac injury in CKD.

Fibrosis, the Bad Actor in Cardiorenal Syndromes: Mechanisms Involved

Cardiorenal syndrome is a term that defines the complex bidirectional nature of the interaction between cardiac and renal disease. It is well established that patients with kidney disease have higher incidence of cardiovascular comorbidities and that renal dysfunction is a significant threat to the prognosis of patients with cardiac disease. Fibrosis is a common characteristic of organ injury progression that has been proposed not only as a marker but also as an important driver of the pathophysiology of cardiorenal syndromes. Due to the relevance of fibrosis, its study might give insight into the mechanisms and targets that could potentially be modulated to prevent fibrosis development. The aim of this review was to summarize some of the pathophysiological pathways involved in the fibrotic damage seen in cardiorenal syndromes, such as inflammation, oxidative stress and endoplasmic reticulum stress, which are known to be triggers and mediators of fibrosis.

Association of Post Transplantation Anaemia and Persistent Secondary Hyperparathyroidism with Diastolic Function in Stable Kidney Transplant Recipients

Introduction

We hypothesized that post transplantation anaemia and persistent secondary hyperparathyroidism are potential determinants of diastolic function in stable kidney transplant recipients.

Methods

We assessed traditional and non-traditional cardiovascular risk factors and determined carotid artery intima-media thickness and plaque by ultrasound, arterial function by applanation tonometry using SphygmoCor software and diastolic function by echocardiography in 43 kidney transplant recipients with a transplant duration of ≥6 months, no acute rejection and a glomerular filtration rate of ≥15 mL/min/1.73m².

Results

Mean (SD; range) transplant duration was 12.3 (8.0; 0.5–33.8) years. Post transplantation anaemia and persistent secondary hyperparathyroidism were identified in 27.9% and 30.8% of the patients, respectively; 67.5% of the participants were overweight or obese. In established confounder adjusted analysis, haemoglobin (partial R=−0.394, p=0.01) and parathyroid hormone concentrations (partial R=0.382, p=0.02) were associated with E/e’. In multivariable analysis, haemoglobin (partial R=−0.278, p=0.01) and parathyroid levels (partial R=0.324, p=0.04) were independently associated with E/e’. Waist–height ratio (partial R=−0.526, p=0.001 and partial R=−0.355, p=0.03), waist circumference (partial R=−0.433, p=0.008 and partial R=−0.393, p=0.02) and body mass index (partial R=−0.332, p=0.04 and partial R=−0.489, p=0.002) were associated with both e’ and E/A, respectively, in established confounder adjusted analysis. The haemoglobin-E/e’ (partial R=−0.422, p=0.02), parathyroid hormone-E/e’ (partial R=0.434, p=0.03), waist–height ratio-e’ (partial R=−0.497, p=0.007) and body mass index-E/A (partial R=−0.386, p=0.04) relationships remained consistent after additional adjustment for left ventricular mass index and cardiac preload and afterload measures.

Conclusion

Haemoglobin and parathyroid hormone concentrations as well as adiposity measures are independently associated with diastolic function in kidney transplant recipients. Whether adequate management of post transplantation anaemia, persistent secondary hyperparathyroidism and excess adiposity can prevent the development of heart failure with preserved ejection fraction in kidney transplant recipients merits further investigation.

Association between Reduced Serum Zinc and Diastolic Dysfunction in Maintenance Hemodialysis Patients

Diastolic dysfunction is an emerging challenge among hemodialysis (HD) patients, and the associations between serum zinc with echocardiographic parameters and diastolic function remain uncertain. A total of 185 maintenance HD patients were stratified by the tertiles of serum zinc level to compare their clinical characteristics and echocardiography. Correlations of serum zinc levels with echocardiographic parameters were examined using Pearson’s analysis. Univariate and multivariate logistic regression analyses were performed to investigate the determinants of E/e’ ratio >15 and left atrial volume index (LAVI) > 34 mL/m², both indicators of diastolic dysfunction. Patients belonging to the first tertile of serum zinc level had a significantly higher E/e’ ratio and LAVI. Serum zinc levels were negatively correlated with E (r = −0.204, p = 0.005), E/e’ ratio (r = −0.217, p = 0.003), and LAVI (r = −0.197, p = 0.007). In a multivariate analysis, older age, diabetes, coronary artery disease, and lower serum zinc levels (OR = 0.974, 95% CI = 0.950–0.999, p = 0.039) were significantly associated with E/e’ ratio >15. Furthermore, diabetes and lower serum zinc levels (OR = 0.978, 95% CI = 0.958–0.999, p = 0.041) were significantly associated with LAVI >34 mL/m². Reduced serum zinc level was significantly associated with diastolic dysfunction among HD patients. Further prospective studies are warranted to investigate whether zinc supplementation can attenuate cardiac dysfunction in maintenance HD patients.