Myocardial interstitial fibrosis in experimental uremia--implications for cardiac compliance

Chronic kidney disease activates the HDAC6-inflammatory axis in the heart and contributes to myocardial remodeling in mice: inhibition of HDAC6 alleviates chronic kidney disease-induced myocardial remodeling

Chronic kidney disease (CKD) adversely affects the heart. The underlying mechanism and the interplay between the kidney and the heart are still obscure. We examined the cardiac effect using the unilateral ureteral obstruction (UUO)-induced CKD pre-clinical model in mice. Echocardiography, histopathology of the heart, myocardial mRNA expression of ANP and BNP, the extent of fibrotic (TGF-β, α-SMA, and collagen I) and epigenetic (histone deacetylases, namely HDAC3, HDAC4, and HDAC6) proteins, and myocardial inflammatory response were assessed. Six weeks of post-UUO surgery, we observed a compromised left-ventricular wall thickness and signs of cardiac hypertrophy, accumulation of fibrosis associated, and inflammatory proteins in the heart. In addition, we observed a perturbation of epigenetic proteins, especially HDAC3, HDAC4, and HDAC6, in the heart. Pharmacological inhibition of HDAC6 using ricolinostat (RIC) lessened cardiac damage and improved left-ventricular wall thickness. The RIC treatment substantially restored the serum cardiac injury markers, namely creatine kinase-MB and lactate dehydrogenase (LDH) activities, ANP and BNP mRNA expression, and heart histological changes. The extent of myocardial fibrotic proteins, phospho-NF-κB (p65), and pro-inflammatory cytokines (TNF-α, IL-18, and IL-1β) were significantly decreased in the RIC treatment group. Further findings revealed the CKD-induced infiltration of CD3, CD8a, CD11c, and F4/80 positive inflammatory cells in the heart. Treatment with RIC substantially reduced the myocardial infiltration of these inflammatory cells. From these findings, we believe that CKD-induced myocardial HDAC6 perturbation has a deteriorative effect on the heart, and inhibition of HDAC6 can be a promising approach to alleviate CKD-induced myocardial remodeling.

Fractal analysis: Left ventricular trabecular complexity cardiac MRI adds independent risks for heart failure with preserved ejection fraction in participants with end-stage renal disease

PURPOSE

To measure left ventricular (LV) trabecular complexity by fractal dimension (FD) in patients with end-stage renal disease (ESRD), and assess whether FD was an independent risk factor for heart failure with preserved ejection fraction (HFpEF), or a significant predictor for adverse outcome in this population.

METHODS

The study retrospectively enrolled 104 participants with ESRD who underwent 3.0 T cardiac magnetic resonance imaging (MRI) from June 2018 to November 2020. LV trabeculation was quantified with fractal analysis of short-axis cine slices to estimate the FD. Logistic regression analyses were used to evaluate FD and cardiac MRI parameters and to find independent risk predictors. Cox proportional hazard regression was used to investigate the association between FD and MACE.

RESULTS

LV FD was higher in in the HFpEF group than those in the non-HFpEF group, with the greatest difference near the base of the ventricle. Age, minimum left atrial volume index, and LV mean basal FD were independent predictors for HFpEF in patients with ESRD. Combining the mean basal FD with typical predictive factors resulted in a C-index (0.902 vs 0.921), which was not significantly higher. Same improvements were found for net reclassification improvement [0.642; 95% confidence interval (CI), 0.254-1.029] and integrated discrimination index (0.026; 95% CI, 0.008-0.061). Participants with a LV global FD above the cutoff value (1.278) had higher risks of MACE in ESRD patients.

CONCLUSIONS

LV trabecular complexity measured by FD was an independent risk factor for HFpEF, and a significant predictor for MACE among patients with ESRD.

Effect of left ventricular mechanical dyssynchrony assessed pre-renal transplantation on cardiovascular death post transplantation

BACKGROUND

SPECT myocardial perfusion imaging (MPI) provides an assessment of LV mechanical dyssynchrony (LVMD) which correlates with CVD outcomes in diverse populations including those awaiting renal transplant (RT). The current study examines the association of LVMD on pre-transplant MPI with long-term CVD mortality post RT.

METHODS

We identified consecutive patients who underwent RT at the University of Alabama at Birmingham between 2008 and 2012 from our prospectively collected database. 675 patients in the database underwent MPI and had images amenable for phase analysis. A blinded investigator retrieved the studies and derived LVMD indices including histogram bandwidth (BW), standard deviation (SD), phase peak, phase skewness, and phase kurtosis. The primary outcome was CVD death after RT.

RESULTS

The study cohort had a median age of 54 years, 56% were men, 43% had diabetes, and 7% had prior myocardial infarction. Patients were on dialysis for a median of 3.4 years prior to RT and 34% received living donor transplants. During a median follow-up time after RT of 4.7 years (IQR 3.5 to 6.3 years) 59 patients (9%) succumbed to CVD death. Patients with wider BW, wider SD, lower skewness, and lower kurtosis had an increased risk of CVD death. On multivariate adjustment, BW and skewness remained as independent predictors of CVD deaths.

CONCLUSIONS

LVMD by phase analysis of gated SPECT MPI is associated with increased risk of CVD death after RT. This association is independent of demographics, comorbidities, and traditional findings on MPI and added incremental prognostic information. Assessment of LVMD should be considered for risk stratification in these patients.

Time-dependent cardiac structural and functional changes after kidney transplantation: a multi-parametric cardiac magnetic resonance study

OBJECTIVES

To map time-dependent cardiac structural and functional change patterns after renal transplantation (KT) using cardiac magnetic resonance (CMR).

METHODS

Fifty-three patients with pre-KT and post-KT CMR exams were retrospectively analyzed. Patients were divided into three groups according to the time of post-KT CMR: group 1 (3 months post-KT, n = 16), group 2 (6 months post-KT, n = 21), and group 3 (over 9 months post-KT, n = 16). Twenty-one age- and sex-matched healthy controls (HC) were recruited for the study. CMR-derived left ventricular (LV) volumes, LV mass index (LVMi), LV ejection fraction (LVEF), global radial strain (GRS), global circumferential strain (GCS), global longitudinal strain (GLS), and native T1 value were compared. The association between the changes of CMR parameters was assessed.

RESULTS

LVMi post-KT decreased in groups 2 (p < 0.001) and 3 (p = 0.004) but both groups had higher LVMi values compared to HC (both p < 0.001). GLS post-KT was decreased in group 1 (p = 0.021), but slightly increased in group 2 (p = 0.728) and group 3 (p = 0.100) without significant difference. GLS post-KT in group 3 was not different from HC (p = 0.104). LVEF, GRS, and GCS post-KT in groups 2 and 3 significantly increased and showed no significant difference from HC. The post-KT native T1 value in all three groups significantly decreased; however, no group showed any significant difference from HC. The change of LVEF was associated with the change of GCS, GRS, and GLS.

CONCLUSIONS

Although GRS, GCS, GLS, and native T1 values reversed to normal level, LVMi remained impaired in median 14 months after KT.

KEY POINTS

• Kidney transplantation has favorable effects on cardiac structure and function. • In a median 14 months of follow-up after KT, left ventricle strain and native T1 value reversed to normal level while LV mass index (LVMi) did not. Left ventricular hypertrophy may help to explain why KT recipients are still at increased cardiovascular risk. • The reason for the decrease of native T1 value after KT may be more than myocardial fibrosis and needs to be further studied.

QT Prolongation in Dialysis Patients: An Epidemiological Study with a Focus on Malnutrition

BACKGROUND/AIMS

QT prolongation is a known risk factor for ventricular fibrillation and ventricular tachycardia. Therefore, more refined management is necessary to reduce sudden cardiac death secondary to such arrhythmias.

METHODS

Electrocardiographic findings were reviewed in 224 patients, and the associations of QT prolongation with various clinical parameters were examined, including the nutritional state. Correlations were also examined between QT prolongation and body composition measurements determined by multifrequency bioelectrical impedance analysis.

RESULTS

Prolongation of the corrected QT (QTc) interval over 0.44 s was seen in 140 patients (62.5%). QT prolongation was independent of age and dialysis therapy duration and was more frequent in diabetics (70.1%) than in nondiabetics (54.2%, p = 0.014) and more frequent in women (78.8%) than in men (53.5%, p < 0.001). Serum levels of albumin (p < 0.001) and Cr (p < 0.001) and the Geriatric Nutritional Risk Index (GNRI, p < 0.001) were negatively correlated with QTc interval; no significant correlation was noted with total protein, urea nitrogen, or uric acid. Negative correlations with QTc interval were found for BMI(p < 0.01), percent total body water (%TBW; p < 0.05), and percent intracellular water (%ICW; p < 0.01) but not with the percent extracellular water/TBW ratio or edema ratio. The longer the QTc interval, the lower the fat-free mass (FFM; p < 0.01) and muscle mass (MM; p < 0.01), but there was no significant correlation with percent fat.

CONCLUSION

These results suggest that QT prolongation is a common complication and is more frequent in women and diabetic patients. The decreases in serum albumin and Cr levels, GNRI, BMI, %TBW, %ICW, FFM, and MM together coincided with malnutrition and thus suggest a close relationship of QT prolongation with malnutrition. Management of QT prolongation may be achieved better in the future by understanding these biochemical and biophysical changes, particularly those regarding malnutrition.

Should We Consider the Cardiovascular System While Evaluating CKD-MBD?

Cardiovascular (CV) disease is highly prevalent in the population with chronic kidney disease (CKD), where the risk of CV death in early stages far exceeds the risk of progression to dialysis. The presence of chronic kidney disease-mineral and bone disorder (CKD-MBD) has shown a strong correlation with CV events and mortality. As a non-atheromatous process, it could be partially explained why standard CV disease-modifying drugs do not provide such an impact on CV mortality in CKD as observed in the general population. We summarize the potential association of CV comorbidities with the older (parathyroid hormone, phosphate) and newer (FGF23, Klotho, sclerostin) CKD-MBD biomarkers.

miR-26a Limits Muscle Wasting and Cardiac Fibrosis through Exosome-Mediated microRNA Transfer in Chronic Kidney Disease

Uremic cardiomyopathy and muscle atrophy are associated with insulin resistance and contribute to chronic kidney disease (CKD)-induced morbidity and mortality. We hypothesized that restoration of miR-26a levels would enhance exosome-mediated microRNA transfer to improve muscle wasting and cardiomyopathy that occur in CKD.

Methods: Using next generation sequencing and qPCR, we found that CKD mice had a decreased level of miR-26a in heart and skeletal muscle. We engineered an exosome vector that contained Lamp2b, an exosomal membrane protein gene fused with a muscle-specific surface peptide that targets muscle delivery. We transfected this vector into muscle satellite cells and then transduced these cells with adenovirus that expresses miR-26a to produce exosomes encapsulated miR-26a (Exo/miR-26a). Exo/miR-26a was injected once per week for 8 weeks into the tibialis anterior (TA) muscle of 5/6 nephrectomized CKD mice.

Results: Treatment with Exo/miR-26a resulted in increased expression of miR-26a in skeletal muscle and heart. Overexpression of miR-26a increased the skeletal muscle cross-sectional area, decreased the upregulation of FBXO32/atrogin-1 and TRIM63/MuRF1 and depressed cardiac fibrosis lesions. In the hearts of CKD mice, FoxO1 was activated, and connective tissue growth factor, fibronectin and collagen type I alpha 1 were increased. These responses were blunted by injection of Exo/miR-26a. Echocardiograms showed that cardiac function was improved in CKD mice treated with Exo/miR-26a.

Conclusion: Overexpression of miR-26a in muscle prevented CKD-induced muscle wasting and attenuated cardiomyopathy via exosome-mediated miR-26a transfer. These results suggest possible therapeutic strategies for using exosome delivery of miR-26a to treat complications of CKD.

Pathological cardiac remodeling occurs early in CKD mice from unilateral urinary obstruction, and is attenuated by Enalapril

Cardiovascular disease constitutes the leading cause of mortality in patients with chronic kidney disease (CKD) and end-stage renal disease. Despite increasing recognition of a close interplay between kidney dysfunction and cardiovascular disease, termed cardiorenal syndrome (CRS), the underlying mechanisms of CRS remain poorly understood. Here we report the development of pathological cardiac hypertrophy and fibrosis in early stage non-uremic CKD. Moderate kidney failure was induced three weeks after unilateral urinary obstruction (UUO) in mice. We observed pathological cardiac hypertrophy and increased fibrosis in UUO-induced CKD (UUO/CKD) animals. Further analysis indicated that this cardiac fibrosis was associated with increased expression of transforming growth factor β (TGF-β) along with significant upregulation of Smad 2/3 signaling in the heart. Moreover early treatment of UUO/CKD animals with an angiotensin-converting-enzyme inhibitor (ACE I), Enalapril, significantly attenuated cardiac fibrosis. Enalapril antagonized activation of the TGF-β signaling pathway in the UUO/CKD heart. In summary our study demonstrates the presence of pathological cardiac hypertrophy and fibrosis in mice early in UUO-induced CKD, in association with early activation of the TGF-β/Smad signaling pathway. We also demonstrate the beneficial effect of ACE I in alleviating this early fibrogenic process in the heart in UUO/CKD animals.

Vasculopathy in the setting of cardiorenal syndrome: roles of protein-bound uremic toxins

Chronic kidney disease (CKD) often leads to and accelerates the progression of cardiovascular disease (CVD), while CVD also causes kidney dysfunction. This bidirectional interaction leads to the development of a complex syndrome known as cardiorenal syndrome (CRS). CRS not only involves both the heart and the kidney but also the vascular system through a vast array of contributing factors. In addition to hemodynamic, neurohormonal, mechanical, and biochemical factors, nondialyzable protein-bound uremic toxins (PBUTs) are also key contributing factors that have been demonstrated through in vitro, in vivo, and clinical observations. PBUTs are ineffectively removed by hemodialysis because their complexes with albumins are larger than the pores of the dialysis membranes. PBUTs such as indoxyl sulfate and p-cresyl sulfate are key determinate and predictive factors for the progression of CVD in CKD patients. In CRS, both vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) exhibit significant dysfunction that is associated with the progression of CVD. PBUTs influence proliferation, calcification, senescence, migration, inflammation, and oxidative stress in VSMCs and ECs through various mechanisms. These pathological changes lead to arterial remodeling, stiffness, and atherosclerosis and thus reduce heart perfusion and impair left ventricular function, aggravating CRS. There is limited literature about the effect of PBUT on the vascular system and their contribution to CRS. This review summarizes current knowledge on how PBUTs influence vasculature, clarifies the relationship between uremic toxin-related vascular disease and CRS, and highlights the potential therapeutic strategies of uremic vasculopathy in the setting of CRS.

Cardiovascular impact in patients undergoing maintenance hemodialysis: Clinical management considerations

Patients undergoing maintenance hemodialysis develop both structural and functional cardiovascular abnormalities. Despite improvement of dialysis technology, cardiovascular mortality of this population remains high. The pathophysiological mechanisms of these changes are complex and not well understood. It has been postulated that several non-traditional, uremic-related risk factors, especially the long-term uremic state, which may affect the cardiovascular system. There are many cardiovascular changes that occur in chronic kidney disease including left ventricular hypertrophy, myocardial fibrosis, microvascular disease, accelerated atherosclerosis and arteriosclerosis. These structural and functional changes in patients receiving chronic dialysis make them more susceptible to myocardial ischemia. Hemodialysis itself may adversely affect the cardiovascular system due to non-physiologic fluid removal, leading to hemodynamic instability and initiation of systemic inflammation. In the past decade there has been growing awareness that pathophysiological mechanisms cause cardiovascular dysfunction in patients on chronic dialysis, and there are now pharmacological and non-pharmacological therapies that may improve the poor quality of life and high mortality rate that these patients experience.

The Impact of Donor and Recipient Renal Dysfunction on Cardiac Allograft Survival: Insights Into Reno-Cardiac Interactions

BACKGROUND

Renal dysfunction (RD) is a potent risk factor for death in patients with cardiovascular disease. This relationship may be causal; experimentally induced RD produces findings such as myocardial necrosis and apoptosis in animals. Cardiac transplantation provides an opportunity to investigate this hypothesis in humans.

METHODS AND RESULTS

Cardiac transplantations from the United Network for Organ Sharing registry were studied (n = 23,056). RD was defined as an estimated glomerular filtration rate <60 mL/min/1.73 m(2). RD was present in 17.9% of donors and 39.4% of recipients. Unlike multiple donor characteristics, such as older age, hypertension, or diabetes, donor RD was not associated with recipient death or retransplantation (age-adjusted hazard ratio [HR] = 1.00, 95% confidence interval [CI] 0.94-1.07, P = .92). Moreover, in recipients with RD the highest risk for death or retransplantation occurred immediately posttransplant (0-30 day HR = 1.8, 95% CI 1.54-2.02, P < .001) with subsequent attenuation of the risk over time (30-365 day HR = 0.92, 95% CI 0.77-1.09, P = .33).

CONCLUSIONS

The risk for adverse recipient outcomes associated with RD does not appear to be transferrable from donor to recipient via the cardiac allograft, and the risk associated with recipient RD is greatest immediately following transplant. These observations suggest that the risk for adverse outcomes associated with RD is likely primarily driven by nonmyocardial factors.

Histomorphometric evaluation of the small coronary arteries in rats exposed to industrial noise

Morphological changes induced by industrial noise (IN) have been experimentally observed in several organs. Histological observations of the coronary arteries showed prominent perivascular tissue and fibrosis among IN-exposed rats. The effects on the small arteries are unknown. Objective: To evaluate the histomorphometric changes induced by IN on rat heart small arteries. Methods: Twenty Wistar rats exposed to IN during a maximum period of seven months and 20 age-matched controls were studied. Hearts were transversely sectioned from ventricular apex to atria and a mid-ventricular fragment was selected for analysis. The histological images were obtained with an optical microscope using 400× magnifications. A total of 634 arterial vessels (298 IN-exposed and 336 controls) were selected. The mean lumen-to-vessel wall (L/W) and mean vessel wall-to-perivascular tissue (W/P) ratios were calculated using image J software. Results: There were no differences between exposed and control animals in their L/W ratios (p = 0.687) and time variations in this ratio were non-significant (p = 0.110). In contrast, exposed animals showed lower W/P ratios than control animals (p < 0.001), with significant time variations (p = 0.004). Conclusions: Industrial noise induced an increase in the perivascular tissue of rat small coronary arteries, with significant development of periarterial fibrosis.

Uric acid increases the incidence of ventricular arrhythmia in patients with left ventricular hypertrophy

BACKGROUNDS

Elevated uric acid (UA) level is reported to be related to the development of left ventricular hypertrophy (LVH) which is associated with high incidence of ventricular tachycardia (VT) and sudden cardiac death. However, little is known about the association between serum UA levels and the occurrence of VT. Thus, we examined the relationship between serum UA levels and the appearance of VT in patients with LVH.

METHODS

The study subjects consisted of 167 patients (110 males, mean age 67.4 ± 12.7 years) with LVH detected by echocardiography. These patients were divided into two groups based on whether VT was presented (defined by more than 5 beats, n = 27) or not (n = 140) by 24-hour Holter ECG monitoring. Left ventricular ejection fraction (LVEF), left ventricular end-diastolic diameter (LVDd), the E/A ratio and deceleration time of transmitral flow velocity were assessed by echocardiography in each group. In addition, blood urea nitrogen (BUN), creatinine, estimated glomerular filtration rate (eGFR), sodium, potassium, hemoglobin, total bilirubin and UA were compared in each group.

RESULTS

Echocardiographic findings did not show the difference between the two groups. However, BUN and UA levels in the VT group were significantly higher than those in the Non-VT group (p < 0.01). eGFR was significantly lower in the VT group than that in the Non-VT group (p < 0.01). A multivariate logistic regression analysis identified the UA level as an independent predictive factor for the occurrence of VT (odds ratio 1.61, 95% confidence interval 1.1-2.2, p < 0.01).

CONCLUSIONS

These results suggest that serum UA level is a useful marker for predicting ventricular arrhythmias in patients with LVH.

Animal models of cardiorenal syndrome: a review

The incidence of heart failure and renal failure is increasing and is associated with poor prognosis. Moreover, these conditions do often coexist and this coexistence results in worsened outcome. Various mechanisms have been proposed as an explanation of this interrelation, including changes in hemodynamics, endothelial dysfunction, inflammation, activation of renin-angiotensin-aldosterone system, and/or sympathetic nervous system. However, the exact mechanisms initializing and maintaining this interaction are still unknown. In many experimental studies on cardiac or renal dysfunction, the function of the other organ was either not addressed or the authors failed to show any decline in its function despite histological changes. There are few studies in which the dysfunction of both heart and kidney function has been described. In this review, we discuss animal models of combined cardiorenal dysfunction. We show that translation of the results from animal studies is limited, and there is a need for new and better models of the cardiorenal interaction to improve our understanding of this syndrome. Finally, we propose several requirements that a new animal model should meet to serve as a tool for studies on the cardiorenal syndrome.

Cardiorenal syndrome: the emerging role of protein-bound uremic toxins

Cardiorenal syndrome is a condition in which a complex interrelationship between cardiac dysfunction and renal dysfunction exists. Despite advances in treatment of both cardiovascular and kidney disease, cardiorenal syndrome remains a major global health problem. Characteristic of the pathophysiology of cardiorenal syndrome is bidirectional cross-talk; mediators/substances activated by the disease state of 1 organ can play a role in worsening dysfunction of the other by exerting their biologically harmful effects, leading to the progression of the syndrome. Accumulation of uremic toxins is a hallmark of renal excretory dysfunction. Removal of some toxins by conventional dialysis is particularly problematic because of their high protein binding. In this review, we demonstrate that protein-bound uremic toxins may play an important role in progression of cardiovascular disease in the setting of chronic kidney disease. The highly protein-bound uremic toxin indoxyl sulfate has emerged as a potent toxin adversely affecting both the kidney and heart. Direct cardiac effects of this toxin have been recently demonstrated both in vitro and in vivo. Specifically, potent fibrogenic and prohypertrophic effects, as well as oxidative stress-inducing effects, appear to play a central role in both renal and cardiac pathology. Many of these adverse effects can be suppressed by use of a gut adsorbent, AST-120. Potential mechanisms underlying indoxyl sulfate-induced cardiorenal fibrosis are discussed. Future research and clinical implications conclude this review.

Pathophysiological model of chronic heart failure complicated with renal failure caused by three-quarter nephrectomy and subcutaneous injection of isoprenaline

This study aimed to investigate the pathophysiological changes in a rat chronic heart failure complicated with renal failure model, caused by three-quarters nephrectomy and subcutaneous injection of isoproterenol (ISO). Sprague-Dawley (SD) rats in the model group received three-quarters nephrectomy after twice undergoing surgical resections and subcutaneous injection of ISO (100 mg/kg body weight, injected twice, with a 24 h interval) after one week, while rats in the control group received sham surgery and injection of normal saline. Survival rate, heart failure and renal failure were compared between the two groups after 4 weeks. Serum creatinine (Cr), blood urea nitrogen (BUN), B-type natriuretic protein (BNP), aldolase (ALD), angiotensin II (Ang II) and C-reactive protein (CRP) were determined by kit assay. Urine protein at 24 h was determined by the Bradford method and left ventricular systolic pressure (LVSP), left ventricular diastolic pressure (LVDP) and left ventricular end-diastolic pressure (LVEDP), as well as the maximum rates of increased and decreased left ventricular pressure (±dP/dt_max) were determined by left ventricular intubation. Heart weight indices were determined and the myocardial pathological conditions were observed by hematoxylin and eosin (HE) staining. There was no death in the control group, while the survival rate of the model group was 73%. Compared with the control group, each index of serum and urine protein in the model group was significantly increased. Additionally, LVSP was decreased, LVDP and LVEDP were increased and heart weight index was increased, with a significant difference. The serum Cr was positively correlated to BNP levels in the model group. Three-quarters nephrectomy and subcutaneous injection of ISO induces left ventricular heart failure and renal failure at the same time, which is characterized in pathophysiology by left ventricular diastolic and systolic function failure, left ventricular myocardial hypertrophy and reconstruction complicated with renal insufficiency.

Prognostic significance of left ventricular hypertrophy observed at dialysis initiation depends on the pre-dialysis use of erythropoiesis-stimulating agents

BACKGROUND

Recent experimental studies suggest that erythropoietin promotes beneficial myocardial remodeling during left ventricular hypertrophy (LVH); however, such compensatory capacity may be limited due to insufficient erythropoietin production in chronic kidney disease patients. Thus, this study aimed to explore the effect of pre-dialysis erythropoiesis-stimulating agent (ESA) use on the prognostic significance of LVH in dialyzed patients.

METHODS

This retrospective study included 404 consecutive patients who started dialysis between 2001 and 2009. The interaction of ESA with the association between left ventricular mass index (LVMI) observed at dialysis initiation and all-cause and cardiovascular mortality was analyzed at the end of 2010 using the Cox model.

RESULTS

During a median follow-up of 36.5 months, 164 patients died, 31 of them from heart failure. The frequency of pre-dialysis ESA use was 58.7 % and median LVMI was 160.3 g/m(2). Of interest, patients with the lowest tertile of LVMI had worse survival compared with those with each subsequent tertile. LVMI was inversely associated with all-cause mortality [hazard ratio (HR) 0.991, 95 % confidence interval (CI) 0.988-0.995, P = 0.000] after extensive adjustment including ejection fraction, whereas the prognostic value of LVMI for cardiovascular mortality was dependent on pre-dialysis ESA use [adjusted HR 1.010, 95 % CI 0.999-1.020, P = 0.065 for pre-dialysis ESA(+) and 0.978, 95 % CI 0.967-0.989, P = 0.000 for pre-dialysis ESA(-), respectively].

CONCLUSIONS

Our results suggest that reverse epidemiology may exist between LVH and mortality and that pre-dialysis ESA use may modify the prognostic significance of LVH observed at dialysis initiation for cardiovascular mortality in dialyzed patients.

Interpreting Cardiac Troponin Results from High-Sensitivity Assays in Chronic Kidney Disease without Acute Coronary Syndrome

BACKGROUND

Quantification and comparison of high-sensitivity (hs) cardiac troponin I (cTnI) and cTnT concentrations in chronic kidney disease (CKD) have not been reported. We examined the associations between hs cTnI and cTnT, cardiovascular disease, and renal function in outpatients with stable CKD.

METHODS

Outpatients (n = 148; 16.9% with prior myocardial infarction or coronary revascularization) with an estimated glomerular filtration rate (eGFR) of &lt;60 mL · min−1 · (1.73 m2)−1 had serum cTnI (99th percentile of a healthy population = 9.0 ng/L), and cTnT (99th percentile = 14 ng/L) measured with hs assays. Left ventricular ejection fraction (LVEF) and mass were assessed by echocardiography, and coronary artery calcification (CAC) was determined by computed tomography. Renal function was estimated by eGFR and urine albumin/creatinine ratio (UACR).

RESULTS

The median (interquartile range) concentrations of cTnI and cTnT were 6.3 (3.4–14.4) ng/L and 17.0 (11.2–31.4) ng/L, respectively; 38% and 68% of patients had a cTnI and cTnT above the 99th percentile, respectively. The median CAC score was 80.8 (0.7–308.6), LV mass index was 85 (73–99) g/m2, and LVEF was 58% (57%–61%). The prevalences of prior coronary disease events, CAC score, and LV mass index were higher with increasing concentrations from both hs cardiac troponin assays (P &lt; 0.05 for all). After adjustment for demographics and risk factors, neither cardiac troponin assay was associated with CAC, but both remained associated with LV mass index as well as eGFR and UACR.

CONCLUSIONS

Increased hs cTnI and cTnT concentrations are common in outpatients with stable CKD and are influenced by both underlying cardiac and renal disease.

Target organ cross talk in cardiorenal syndrome: animal models

The combination of chronic kidney disease (CKD) and heart failure (HF) is associated with an adverse prognosis. Although clinical studies hint at a specific bidirectional interaction between HF and CKD, insight into the pathogenesis of cardiorenal syndrome (CRS) remains limited. We review available evidence on cardiorenal interactions from animal models of CKD and HF and discuss several studies that employed a "double-hit" model to research organ cross talk between the heart and kidneys. Regarding cardiac changes in CKD models, parameters of cardiac remodeling are equivocal and cardiac systolic function generally remains preserved. Structural changes include hypertrophy, fibrosis, and microvasculopathy. In models of HF, data on renal pathology are mostly limited to functional hemodynamic changes. Most double-hit models were unable to show that combined renal and cardiac injury induces additive damage to both organs, perhaps because of the short study duration or absence of organ failure. Because of this lack of "dual-failure" models, we have developed two rat models of combined CKD and HF in which renal dysfunction induced by a subtotal nephrectomy preceded cardiac dysfunction. Cardiac dysfunction was induced either functionally by nitric oxide depletion or structurally by myocardial infarction. In both models, we found that cardiac remodeling and failure were worse in CKD rats compared with controls undergoing the same cardiac insult. Variables of renal damage, like glomerulosclerosis and proteinuria, were also further worsened by combined cardiorenal injury. These studies show that target organ cross talk does occur in CRS. These models may be useful for interventional studies in rats.

Left ventricular periostin gene expression is associated with fibrogenesis in experimental renal insufficiency

BACKGROUND

Cardiovascular diseases are the most important cause of death in patients with impaired kidney function. Left ventricular hypertrophy (LVH), cardiac interstitial fibrosis and cardiovascular calcifications are characteristic of chronic renal insufficiency (CRI). Periostin is a fibrogenesis- and calcification-related matricellular protein re-expressed in adult tissues undergoing remodelling in response to pathological stimuli. The role of periostin in CRI-induced LVH is unknown.

METHODS

Rats were 5/6-nephrectomized (NX), and after 15 weeks of disease progression high-calcium, high-phosphate or paricalcitol treatment was given for 12 weeks. Cardiac tissue and blood samples were taken to study periostin gene expression and to determine factors contributing to its reactivation, respectively. Left ventricular (LV) periostin expression was also examined in response to angiotensin II or arginine(8)-vasopressin (AVP)-induced pressure overload and in spontaneously hypertensive rats.

RESULTS

CRI resulted in a 6.5-fold increase in LV periostin messenger RNA (mRNA) levels. Positive extracellular immunostaining for periostin was detected in areas of infiltrated inflammatory cells and fibrotic lesions. There was a significant correlation between LV periostin mRNA levels and plasma biomarkers of impaired kidney function, LVH, fibrogenesis-related proteins osteopontin and osteoactivin, and anti-calcific matrix Gla protein. Moreover, LV periostin gene expression in CRI correlated positively with systolic blood pressure (BP) and was activated rapidly in response to angiotensin II or AVP infusions.

CONCLUSIONS

Periostin is involved in fibrotic cardiac remodelling in CRI. The re-expression of periostin is localized to the fibrotic and inflammatory lesions and is most likely the consequence of elevated BP.

Chronic kidney disease elicits excessive increase in left ventricular mass growth in patients at increased risk for cardiovascular events

BACKGROUND

The hemodynamic alterations induced by the impairment of renal function explain only in part the development of left ventricular hypertrophy in patients with chronic kidney disease (CKD), who are theoretically exposed to an inappropriate high growth of left ventricular mass (iLVM) due to the activation of neuro-hormonal stressors. Few data are available on the relations between iLVM and renal function.

STUDY DESIGN AND MEASUREMENTS

Three hundred and forty individuals at increased risk for cardiovascular events underwent assessment of renal function by the estimation of glomerular filtration rate (eGFR) and echocardiography: 227 patients had stages 1-2 CKD (eGFR ≥60 ml/min per 1.73 m), and 113 stages 3-5 (eGFR <60 ml/min per 1.73 m). LVM was predicted in each patient from height, sex and stroke work using a validated equation. iLVM was defined as LVM more than 28% of the predicted value. Sixty-eight healthy individuals served as controls.

RESULTS

iLVM was detected in seven controls (10%) and in 146 study patients (43%). There was an inverse relation between observed/predicted LVM ratio and eGFR (r 0.54, P < 0.001). In linear regression analysis, iLVM was related to eGFR (β 0.40), relative wall thickness (β 0.29), diabetes (β 0.14), and maximal left atrial volume (β 0.25) (all P < 0.001). Prevalence of iLVM was 10% in patients in stage-1 CKD, 31% in stage 2, 67% in stage 3, and 100% in stages 4 and 5.

CONCLUSION

In patients at increased risk for cardiovascular events, iLVM is strongly related to the presence and magnitude of CKD. Further longitudinal studies are needed to evaluate the prognostic value of the coexistence of iLVM and CKD.

High-dose enalapril treatment reverses myocardial fibrosis in experimental uremic cardiomyopathy

AIMS

Patients with renal failure develop cardiovascular alterations which contribute to the higher rate of cardiac death. Blockade of the renin angiotensin system ameliorates the development of such changes. It is unclear, however, to what extent ACE-inhibitors can also reverse existing cardiovascular alterations. Therefore, we investigated the effect of high dose enalapril treatment on these alterations.

METHODS

Male Sprague Dawley rats underwent subtotal nephrectomy (SNX, n = 34) or sham operation (sham, n = 39). Eight weeks after surgery, rats were sacrificed or allocated to treatment with either high-dose enalapril, combination of furosemide/dihydralazine or solvent for 4 weeks. Heart and aorta were evaluated using morphometry, stereological techniques and TaqMan PCR.

RESULTS

After 8 and 12 weeks systolic blood pressure, albumin excretion, and left ventricular weight were significantly higher in untreated SNX compared to sham. Twelve weeks after SNX a significantly higher volume density of cardiac interstitial tissue (2.57±0.43% in SNX vs 1.50±0.43% in sham, p<0.05) and a significantly lower capillary length density (4532±355 mm/mm(3) in SNX vs 5023±624 mm/mm(3) in sham, p<0.05) were found. Treatment of SNX with enalapril from week 8-12 significantly improved myocardial fibrosis (1.63±0.25%, p<0.05), but not capillary reduction (3908±486 mm/mm(3)) or increased intercapillary distance. In contrast, alternative antihypertensive treatment showed no such effect. Significantly increased media thickness together with decreased vascular smooth muscles cell number and a disarray of elastic fibres were found in the aorta of SNX animals compared to sham. Both antihypertensive treatments failed to cause complete regression of these alterations.

CONCLUSIONS

The study indicates that high dose ACE-I treatment causes partial, but not complete, reversal of cardiovascular changes in SNX.

Experimental models of renal disease and the cardiovascular system

Cardiovascular disease is a leading cause of death among patients with end stage renal failure. Animal models have played a crucial role in teasing apart the complex pathological processes involved. This review discusses the principles of using animal models, the history of their use in the study of renal hypertension, the controversies arising from experimental models of non-hypertensive uraemic cardiomyopathy and the lessons learned from these models, and highlights important areas of future research in this field, including de novo cardiomyopathy secondary to renal transplantation.

A prospective echocardiographic evaluation of pulmonary hypertension in chronic hemodialysis patients in the United States: prevalence and clinical significance

BACKGROUND

Pulmonary hypertension (PH), a disease which carries substantial morbidity and mortality, has been reported to occur in 25%-45% of dialysis patients. No prospective evaluation of the prevalence or clinical significance of PH in chronic dialysis patients in the United States (US) has been undertaken.

METHODS

Echocardiograms were performed prospectively in chronic hemodialysis patients prior to dialysis at a single dialysis center. PH was defined as a tricuspid regurgitant jet ≥2.5 m/s and "more severe PH" as ≥3.0 m/s. Clinical outcomes recovered were all-cause hospitalizations and death at 12 months.

RESULTS

In a cohort of 90 patients, 42 patients (47%) met the definition of PH. Of those, 18 patients (20%) met the definition of more severe PH. At 12 months, mortality was significantly higher in patients with PH (26%) compared with patients without PH (6%). All-cause hospitalizations were similar in patients with PH and without PH. Echocardiographic findings suggesting impaired left ventricular function and elevated pulmonary capillary wedge pressure were significantly associated with PH.

CONCLUSION

This prospective cross-sectional study of a single dialysis unit suggests that PH may be present in nearly half of US dialysis patients and when present is associated with increased mortality. Echocardiographic findings demonstrate an association between elevated filling pressures, elevated pulmonary artery pressures, and higher mortality, suggesting that the PH may be secondary to diastolic dysfunction and compounded by volume overload.

Left ventricular mechanical dyssynchrony by phase analysis of gated single photon emission computed tomography in end-stage renal disease

The presence and degree of left ventricular (LV) dyssynchrony in patients with end-stage renal disease (ESRD) has not been well studied. We hypothesized that these patients would be more likely to have mechanical dyssynchrony than a control cohort. The indexes of LV mechanical dyssynchrony were measured by automated analysis of gated single photon emission computed tomography myocardial perfusion imaging in 290 patients with ESRD and 109 control patients. Only patients with normal myocardial perfusion imaging findings and a narrow QRS duration were included. The following variables were derived: LV ejection fraction (EF), volume, mass, and 2 indexes of dyssynchrony, the standard deviation and bandwidth. The standard deviation and bandwidth were significantly greater in those with ESRD (23° ± 13° vs 15° ± 6° and 65° ± 40° vs 42° ± 14°, respectively, p <0.001 for each). The LV volumes and LV mass were significantly lower and LVEF significantly greater in the control group than in the patients with ESRD (p <0.001 for each). The subgroup of 217 patients with ESRD and normal LVEF also had a significantly greater standard deviation and bandwidth than did the control group (21° ± 12° and 57° ± 35°, p <0.001 for each). However, their values were lower than those of the 73 patients with ESRD and a LVEF <50% (30° ± 13° and 90° ± 45°, p <0.001 for each). Finally, 25 patients (9%) with ESRD and none of the control group had a standard deviation >43° (p = 0.01). In conclusion, patients with ESRD had significantly more mechanical dyssynchrony than did the control group, even in absence of electrical dyssynchrony and abnormal LV perfusion or function.

Cellular basis of uraemic cardiomyopathy: a role for erythropoietin?

The use of erythropoietin (EPO) has revolutionized the treatment of anaemia associated with many conditions including chronic kidney disease (CKD). However, little is known of the cellular impact of EPO on the uraemic heart. The discovery that the EPO receptor (EPOR) is also expressed on non-haematopoietic cells including cardiomyocytes highlights a role of EPO beyond haematopoiesis. Animal models of heart failure have shown EPO can potentially reverse cardiac remodelling and improve myocardial function. Damage to the kidney, during uraemia, results in a decreased EPO production, which may render the uraemic heart more susceptible to damage and heart failure. Here we review current data on the cellular actions of EPO in models of left ventricular hypertrophy and heart failure and highlight parallels with the uraemic heart.

Uremic cardiomyopathy and insulin resistance: a critical role for akt?

Uremic cardiomyopathy is a classic complication of chronic renal failure whose cause is unclear and treatment remains disappointing. Insulin resistance is an independent predictor of cardiovascular mortality in chronic renal failure. Underlying insulin resistance are defects in insulin signaling through the protein kinase, Akt. Akt acts as a nodal point in the control of both the metabolic and pleiotropic effects of insulin. Imbalance among these effects leads to cardiac hypertrophy, fibrosis, and apoptosis; less angiogenesis; metabolic remodeling; and altered calcium cycling, all key features of uremic cardiomyopathy. Here we consider the role of Akt in the development of uremic cardiomyopathy, drawing parallels from models of hypertrophic cardiac disease.

Transient nitric oxide reduction induces permanent cardiac systolic dysfunction and worsens kidney damage in rats with chronic kidney disease

Left ventricular systolic dysfunction (LVSD) in patients with chronic kidney disease (CKD) is associated with poorer prognosis. Because patients with CKD often exhibit progressively decreased nitric oxide (NO) availability and inhibition of NO production can reduce cardiac output, we hypothesized that loss of NO availability in CKD contributes to pathogenesis of LVSD. Subtotally nephrectomized (SNX) rats were treated with a low dose of the NO synthase inhibitor Nω-nitro-l-arginine (l-NNA; 20 mg/l water; SNX+l-NNA) and compared with relevant control groups. To study permanent changes separate from hemodynamic effects, l-NNA was stopped after week 8 and rats were followed up to week 15, until blood pressure was similar in SNX+l-NNA and SNX groups. To study effects of NO depletion alone, a control group with high-dose l-NNA (l-NNA-High: 100 mg/l) was included. Mild systolic dysfunction developed at week 13 after SNX. In SNX+l-NNA, systolic function decreased by almost 50% already from week 4 onward, together with markedly reduced whole body NO production and high mortality. In l-NNA-High, LVSD was not as severe as in SNX+l-NNA, and renal function was not affected. Both LVSD and NO depletion were reversible in l-NNA-High after l-NNA was stopped, but both were persistently low in SNX+l-NNA. Proteinuria increased compared with rats with SNX, and glomerulosclerosis and cardiac fibrosis were worsened. We conclude that SNX+l-NNA induced accelerated and permanent LVSD that was functionally and structurally different from CKD or NO depletion alone. Availability of NO appears to play a pivotal role in maintaining cardiac function in CKD.

Novel markers of left ventricular hypertrophy in uremia

AIMS

Left ventricular hypertrophy (LVH) is the most frequent cardiac complication in chronic renal disease. Previous studies implicate elevated serum phosphorus as a risk factor for LVH.

METHODS

We treated 5/6 nephrectomized rats with enalapril or enalapril + sevelamer carbonate for 4 months to determine if sevelamer carbonate had an additional beneficial effect on the development of LVH and uremia-induced left ventricle (LV) remodeling.

RESULTS

Uremia increased LV weight and cardiomyocyte size. Enalapril and enalapril + sevelamer blunted the increase in left ventricular weight. Only enalapril + sevelamer diminished the increase in cardiomyocyte size. Uremia increased cyclin D2 and PCNA and decreased p27 protein expression in the heart. Enalapril + sevelamer diminished the decrease in p27 expression caused by uremia. Uremia increased Ki67-positive and phosphohistone H(3)-positive interstitial cells. This was not seen in cardiomyocytes. Multivariable regression analysis showed that increased phosphorus was an independent risk factor for both increased LV weight and cardiomyocyte size.

CONCLUSIONS

These data suggest left ventricular remodeling consists of cardiomyocyte hypertrophy and interstitial cell proliferation, but not cardiomyocyte proliferation. p27 and cyclin D2 may play important roles in the development of LVH. In addition, phosphorus can be an independent risk factor for the development of LVH.

Atrial fibrillation in hemodialysis patients: clinical features and associations with anticoagulant therapy

Using data from the international Dialysis Outcomes and Practice Patterns Study (DOPPS), we determined incidence, prevalence, and outcomes among hemodialysis patients with atrial fibrillation. Cox proportional hazards models, to identify associations with newly diagnosed atrial fibrillation and clinical outcomes, were stratified by country and study phase and adjusted for descriptive characteristics and comorbidities. Of 17,513 randomly sampled patients, 2188 had preexisting atrial fibrillation, with wide variation in prevalence across countries. Advanced age, non-black race, higher facility mean dialysate calcium, prosthetic heart valves, and valvular heart disease were associated with higher risk of new atrial fibrillation. Atrial fibrillation at study enrollment was positively associated with all-cause mortality and stroke. The CHADS2 score identified approximately equal-size groups of hemodialysis patients with atrial fibrillation with low (less than 2) and higher risk (more than 4) for subsequent strokes on a per 100 patient-year basis. Among patients with atrial fibrillation, warfarin use was associated with a significantly higher stroke risk, particularly in those over 75 years of age. Our study shows that atrial fibrillation is common and associated with elevated risk of adverse clinical outcomes, and this risk is even higher among elderly patients prescribed warfarin. The effectiveness and safety of warfarin in hemodialysis patients require additional investigation.

Fibroblast growth factor 23 and left ventricular hypertrophy in chronic kidney disease

BACKGROUND

Fibroblast growth factor 23 (FGF-23) is a phosphorus-regulating hormone. In chronic kidney disease (CKD), circulating FGF-23 levels are markedly elevated and independently associated with mortality. Left ventricular hypertrophy and coronary artery calcification are potent risk factors for mortality in CKD, and FGFs have been implicated in the pathogenesis of both myocardial hypertrophy and atherosclerosis. We conducted a cross-sectional study to test the hypothesis that elevated FGF-23 concentrations are associated with left ventricular hypertrophy and coronary artery calcification in patients with CKD.

METHODS AND RESULTS

In this study, 162 subjects with CKD underwent echocardiograms and computed tomography scans to assess left ventricular mass index and coronary artery calcification; echocardiograms also were obtained in 58 subjects without CKD. In multivariable-adjusted regression analyses in the overall sample, increased log FGF-23 concentrations were independently associated with increased left ventricular mass index (5% increase per 1-SD increase in log FGF-23; P=0.01) and risk of left ventricular hypertrophy (odds ratio per 1-SD increase in log FGF-23, 2.1; 95% confidence interval, 1.03 to 4.2). These associations strengthened in analyses restricted to the CKD subjects (11% increase in left ventricular mass index per 1-SD increase in log FGF-23; P=0.01; odds ratio of left ventricular hypertrophy per 1-SD increase in log FGF-23, 2.3; 95% confidence interval, 1.2 to 4.2). Although the highest tertile of FGF-23 was associated with a 2.4-fold increased risk of coronary artery calcification > or =100 versus <100 U compared with the lowest tertile (95% confidence interval, 1.1 to 5.5), the association was no longer significant after multivariable adjustment.

CONCLUSIONS

FGF-23 is independently associated with left ventricular mass index and left ventricular hypertrophy in patients with CKD. Whether increased FGF-23 is a marker or a potential mechanism of myocardial hypertrophy in CKD requires further study.

Fibroblast growth factor 23 and left ventricular hypertrophy in chronic kidney disease

BACKGROUND

Fibroblast growth factor 23 (FGF-23) is a phosphorus-regulating hormone. In chronic kidney disease (CKD), circulating FGF-23 levels are markedly elevated and independently associated with mortality. Left ventricular hypertrophy and coronary artery calcification are potent risk factors for mortality in CKD, and FGFs have been implicated in the pathogenesis of both myocardial hypertrophy and atherosclerosis. We conducted a cross-sectional study to test the hypothesis that elevated FGF-23 concentrations are associated with left ventricular hypertrophy and coronary artery calcification in patients with CKD.

METHODS AND RESULTS

In this study, 162 subjects with CKD underwent echocardiograms and computed tomography scans to assess left ventricular mass index and coronary artery calcification; echocardiograms also were obtained in 58 subjects without CKD. In multivariable-adjusted regression analyses in the overall sample, increased log FGF-23 concentrations were independently associated with increased left ventricular mass index (5% increase per 1-SD increase in log FGF-23; P=0.01) and risk of left ventricular hypertrophy (odds ratio per 1-SD increase in log FGF-23, 2.1; 95% confidence interval, 1.03 to 4.2). These associations strengthened in analyses restricted to the CKD subjects (11% increase in left ventricular mass index per 1-SD increase in log FGF-23; P=0.01; odds ratio of left ventricular hypertrophy per 1-SD increase in log FGF-23, 2.3; 95% confidence interval, 1.2 to 4.2). Although the highest tertile of FGF-23 was associated with a 2.4-fold increased risk of coronary artery calcification > or =100 versus <100 U compared with the lowest tertile (95% confidence interval, 1.1 to 5.5), the association was no longer significant after multivariable adjustment.

CONCLUSIONS

FGF-23 is independently associated with left ventricular mass index and left ventricular hypertrophy in patients with CKD. Whether increased FGF-23 is a marker or a potential mechanism of myocardial hypertrophy in CKD requires further study.

Expression and tissue localization of beta-catenin, alpha-actinin and chondroitin sulfate proteoglycan 6 is modulated during rat and human left ventricular hypertrophy

Left ventricular hypertrophy (LVH) correlates with chronic renal failure and is one of the most important causes of cardiac mortality. The understanding of the molecular complexity of the disease will help to find biomarkers that open new perspectives about early diagnosis and therapy. This work describes the identification of mediators during pathogenesis relevant for structural remodeling processes of cardiac tissue in uremic LVH. An established rat model of chronic renal failure allowed whole-genome transcriptome analyses as well as the investigation of differential expressed proteins in uremic LVH. The localization of potential biomarkers encoded by candidate genes was done by immunohistochemical analyses of cardiac tissue of the animal model as well as cardiac sections of LVH diseased patients. In addition, the induction of human cardiac fibroblasts (HCF) and human umbilical vein endothelial cells (HUVEC) with the LVH mediator angiotensin II enabled us to investigate uremic LVH progression in vitro. These results point to alterations of myocardial intercellular and cell-matrix contacts in hypertrophic cardiac tissue. Obviously, structural changes of the extracellular matrix are significantly modulated by beta-catenin associated signaling pathways. Interestingly, intracellular translocation of beta-catenin, alpha-actinin and chondroitin sulfate proteoglycan 6 (CSPG6/SMC3) was observed in the animal model and in LVH patients. Our results show that the parallel investigation of rat and human cardiac tissue as well as human cellular models in vitro represents a promising strategy to identify reliable biomarkers of LVH.

Evidence of left ventricular systolic and diastolic dysfunction by color tissue Doppler imaging despite normal ejection fraction in patients on chronic hemodialysis program

BACKGROUND

Cardiovascular diseases are responsible for about half of deaths and are the major cause of mortality in hemodialysis patients. The aim of this study is to assess left ventricular (LV) longitudinal myocardial functions by color tissue Doppler imaging (TDI) in patients with chronic renal failure on a regular hemodialysis program.

METHODS

Thirty-one patients on a regular hemodialysis program (mean age 47 +/- 12 years; 17 males, 14 females) were included into the study. Twenty-three healthy subjects (mean age 44 +/- 8 years; 15 males, 8 females) were studied as a control group. The patients had been on maintenance hemodialysis for at least 1 month and hemodialysis sessions were three times per week. For color TDI, apical two- and four-chamber views of left ventricle were used. Sample volumes were placed on the mid-left ventricle in the inner half of the myocardium at the septum, lateral, inferior, and anterior walls. Peak LV strain, peak systolic strain rate, peak early diastolic strain rate, peak late diastolic strain rate, peak systolic tissue velocity, peak early diastolic tissue velocity, and peak late diastolic tissue velocity values were measured.

RESULTS

Mean peak LV strain, mean peak systolic strain rate, and mean peak systolic tissue velocity values were all lower in the hemodialysis group. Although mean peak late diastolic strain rate and mean peak late diastolic tissue velocity values were similar between the groups, mean peak early diastolic strain rate and mean peak early diastolic tissue velocity values were lower in the hemodialysis group.

CONCLUSION

Patients with chronic renal failure on regular hemodialysis program show significant alterations at LV longitudinal myocardial function parameters assessed by color TDI.

Hypertrophy and fibrosis in the cardiomyopathy of uremia--beyond coronary heart disease

Cardiac disease is the leading cause of death in uremic patients. In contrast to previous opinion, coronary events account for a relatively small proportion of cardiac deaths, the most common causes being sudden death and heart failure. Against this background the current text will discuss noncoronary cardiac pathology, specifically the pathogenesis and the morphological findings caused by (pathological) cardiac hypertrophy, cardiac interstitial fibrosis and microvascular disease.

Mineralocorticoid receptor antagonism attenuates cardiac hypertrophy and prevents oxidative stress in uremic rats

Chronic renal failure causes left ventricular hypertrophy, but the molecular mechanisms involved remain unknown. We, therefore, investigated whether the mineralocorticoid receptor is implicated in the cardiac hypertrophy observed in uremic rats and whether mineralocorticoid receptor blockade could be protective in chronic renal failure. Experimental groups were: control rats, uremic rats (NPX) with 5/6 nephrectomy (5 weeks), and NPX rats fed with spironolactone for 5 weeks. Systolic blood pressure was increased in both NPX rats and NPX rats fed with spironolactone for 5 weeks. Echocardiography revealed concentric left ventricular hypertrophy in uremia, which was attenuated by spironolactone. Enlarged cardiomyocyte size was observed in both left and right ventricles of NPX rats, an effect that was prevented by spironolactone. Mineralocorticoid receptor antagonism attenuated the increase of ventricular brain natriuretic peptide mRNA levels induced by nephrectomy. Left ventricular gene expressions of aldosterone synthase, mineralocorticoid receptor, and hydroxysteroid dehydrogenase type 2 were the same in the 3 groups, whereas gene expression of the glucocorticoid receptor was significantly diminished in chronic renal failure rats. No significant differences in cardiac aldosterone were observed between control rats and NPX rats, although NPX rats fed with spironolactone for 5 weeks showed increased plasma aldosterone levels. However, a significant increase in serum and glucocorticoid-inducible kinase-1 mRNA expression and protein was present in the NPX group; spironolactone treatment significantly reduced serum and glucocorticoid-inducible kinase-1 mRNA and protein in the left ventricle. Uremic rats exhibited a significant increase of superoxide production and reduced nicotinamide-adenine dinucleotide phosphate oxidase subunits expression (NOX-2, NOX-4, and p47(phox)) in the left ventricle, which was prevented by the mineralocorticoid receptor antagonist. Our findings provide evidence of the beneficial effects of spironolactone in cardiac hypertrophy and cardiac oxidative stress in chronic renal failure.

A single session of haemodialysis improves left ventricular synchronicity in patients with end-stage renal disease: a pilot tissue synchronization imaging study

BACKGROUND

Mechanical left ventricular (LV) dyssynchrony impairs cardiac function in patients with heart failure and LV hypertrophy (LVH) and may be a factor contributing to the high incidence of cardiac deaths in patients with end-stage renal disease (ESRD). Objectives. To evaluate the possible presence of LV dyssynchrony in ESRD patients, and acute effect of haemodialysis (HD) on LV synchronicity using a tailored echocardiographic modality, tissue synchronization imaging (TSI).

METHODS

In 13 clinically stable ESRD patients (7 men; 65 +/- 10 years) with LVH, echocardiography data were acquired before and after a single HD session for subsequent off-line TSI analysis enabling the retrieval of regional intraventricular systolic delay data. Six basal and six midventricular LV segments were evaluated. Dyssynchrony was defined as a regional difference in time to peak systolic velocity >105 ms.

RESULTS

Before HD, all patients had at least one dyssynchronous LV segment. The percentage of delayed segments correlated positively to LV end-diastolic diameter (r = 0.68, P < 0.05). HD induced a substantial decrease in the percentage of delayed segments from 36 +/- 25% to 19 +/- 14% (P < 0.01), reduced average maximal mechanical systolic LV delay from 300 +/- 89 to 225 +/- 116 ms (P < 0.05) and completely normalized LV synchronicity in three patients (23%).

CONCLUSIONS

LV dyssynchrony appears to be present frequently in ESRD patients with LVH. The severity of LV dyssynchrony correlates with LV end-diastolic diameter and decreases after a single session of HD suggesting a mechanistic relevance of volume overload and possibly other toxins accumulating in HD patients.

Myocardial infarction does not further impair renal damage in 5/6 nephrectomized rats

BACKGROUND

Recent observational studies show that reduced renal function is an independent risk factor for the development of cardiovascular disease. Previously, we reported that myocardial infarction (MI) indeed enhanced mild renal function decline in rats after unilateral nephrectomy (NX) and that RAAS intervention inhibited this decline. The effects of an MI on pre-existing severe renal function loss and the effects of RAAS intervention interrupting this hypothesized cardiorenal interaction are however unknown and clinically even more relevant.

METHODS

Male Wistar rats underwent MI, sham MI, 5/6NX, or 5/6NX and MI. Six weeks later, the NX rats were treated with an angiotensin-converting enzyme inhibitor (ACEi) or vehicle for 6 weeks.

RESULTS

An MI did not significantly induce more proteinuria (303 +/- 46 versus 265 +/- 24 mg/24 h) and glomerulosclerosis (40 +/- 11 versus 28 +/- 4 arbitrary units) in 5/6NX+MI compared to 5/6NX, and ACEi therapy was equally effective in reducing renal damage in these groups. In the 5/6NX+MI group, decreased renal blood flow and creatinine clearance were observed compared to 5/6NX (2.2 +/- 0.6 versus 3.6 +/- 0.4 ml/min/kg and 2.1 +/- 0.3 versus 2.9 +/- 0.3 ml/min/kg), which both increased after ACEi to levels comparable found in the group that underwent 5/6NX alone.

CONCLUSIONS

MI does not further deteriorate structural renal damage induced by 5/6NX compared with 5/6NX alone. Furthermore, renal haemodynamic impairment occurs after MI, which can be improved applying ACEi therapy. Therefore, we conclude that treatment with ACEi should be optimized in patients with chronic kidney disease after MI to improve renal function.

The effectiveness of renal transplantation as a treatment for recurrent uremic cardiomyopathy

Congestive heart failure is more prevalent in patients with end-stage renal disease than in the general population. Although optimal treatment has yet to be defined, these patients are considered to be at high risk for renal transplantation. The present report of a 27-year-old man describes a full recovery from uremic cardiomyopathy following a renal transplant. Despite the patient developing recurrent cardiac dysfunction following graft failure, a second transplant was successful, which, again, resulted in complete resolution of the cardiomyopathy. Patients with recurrent uremic cardiomyopathy following failed kidney transplantation should be considered for a second kidney transplant.

[Kidney insufficiency and cardiovascular disease]

Cardiovascular disease (CVD) is the leading cause of mortality and morbidity in patients with chronic renal disease. Severe cardiac and arterial disorders such as left ventricular hypertrophy, coronary artery disease, and arteriosclerosis of the large vessels are already evident in early renal disease, even in young patients. Despite major advances in dialysis therapy and treatment options for acute coronary syndromes, mortality remains high--up to 10-30 times higher than in the general population. The increased risk for cardiovascular disorders results from the additive effect of traditional risk factors, volume overload, and endocrine and metabolic abnormalities in uremia. During the course of the renal disease, the progression of CVD disease manifestations significantly influences outcome. Thus, preventive measures and optimal treatment are mandatory and should be among the main targets of early management of patients with chronic renal disease.