Echocardiographic manifestations in end-stage renal disease

End-stage renal disease (ESRD) is a common but profound clinical condition, and it is associated with extremely increased morbidity and mortality. ESRD can represent four major echocardiographic findings-myocardial hypertrophy, heart failure, valvular calcification, and pericardial effusion. Multiple factors interplay leading to these abnormalities, including pressure/volume overload, oxidative stress, and neurohormonal imbalances. Uremic cardiomyopathy is characterized by left ventricular (LV) hypertrophy and marked diastolic dysfunction. In ESRD patients on hemodialysis, LV geometry is changeable bidirectionally between concentric and eccentric hypertrophy, depending upon changes in corporal fluid volume and arterial pressure, which eventually results in a characteristic of LV systolic dysfunction. Speckle tracking echocardiography enabling to detect subclinical disease might help prevent future advancement to heart failure. Heart valve calcification also is common in ESRD, keeping in mind which progresses faster than expected. In a modern era, pericardial effusion observed in ESRD patients tends to result from volume overload, rather than pericarditis. In this review, we introduce and discuss those four echocardiography-assessed findings of ESRD, with which known and conceivable pathophysiologies for each are incorporated.

A novel mouse model of calcific aortic valve stenosis

BACKGROUND

Calcific aortic valve stenosis (CAVS) is one of the most challenging heart diseases in clinical with rapidly increasing prevalence. However, study of the mechanism and treatment of CAVS is hampered by the lack of suitable, robust and efficient models that develop hemodynamically significant stenosis and typical calcium deposition. Here, we aim to establish a mouse model to mimic the development and features of CAVS.

METHODS

The model was established via aortic valve wire injury (AVWI) combined with vitamin D subcutaneous injected in wild type C57/BL6 mice. Serial transthoracic echocardiography was applied to evaluate aortic jet peak velocity and mean gradient. Histopathological specimens were collected and examined in respect of valve thickening, calcium deposition, collagen accumulation, osteogenic differentiation and inflammation.

RESULTS

Serial transthoracic echocardiography revealed that aortic jet peak velocity and mean gradient increased from 7 days post model establishment in a time dependent manner and tended to be stable at 28 days. Compared with the sham group, simple AVWI or the vitamin D group, the hybrid model group showed typical pathological features of CAVS, including hemodynamic alterations, increased aortic valve thickening, calcium deposition, collagen accumulation at 28 days. In addition, osteogenic differentiation, fibrosis and inflammation, which play critical roles in the development of CAVS, were observed in the hybrid model.

CONCLUSIONS

We established a novel mouse model of CAVS that could be induced efficiently, robustly and economically, and without genetic intervention. It provides a fast track to explore the underlying mechanisms of CAVS and to identify more effective pharmacological targets.

Decreased expression of RPL15 and RPL18 exacerbated the calcification of valve interstitial cells during aortic valve calcification

Calcific aortic valve disease (CAVD) is the most common valvular heart disease, with an increasing prevalence due to an aging population. The pathobiology of CAVD is a multifaceted and actively regulated process, but the detailed mechanisms have not been elucidated. The present study aims to identify the differentially expressed genes (DEGs) in calcified aortic valve tissues, and to analyze the correlation between DEGs and clinical features in CAVD patients. The DEGs were screened by microarray in normal and CAVD groups (n = 2 for each group), and confirmed by quantitative real-time polymerase chain reaction in normal (n = 12) and calcified aortic valve tissues (n = 34). A total of 1048 DEGs were identified in calcified aortic valve tissues, including 227 upregulated mRNAs and 821 downregulated mRNAs. Based on multiple bioinformatic analyses, three 60S ribosomal subunit components (RPL15, RPL18, and RPL18A), and two 40S ribosomal subunit components (RPS15 and RPS21) were identified as the top 5 hub genes in the protein-protein interaction network of DEGs. The expression of RPL15 and RPL18 was also found significantly decreased in calcified aortic valve tissues (both p < .01), and negatively correlated with the osteogenic differentiation marker OPN in CAVD patients (both p < .01). Moreover, inhibition of RPL15 or RPL18 exacerbated the calcification of valve interstitial cells under osteogenic induction conditions. The present study proved that decreased expression of RPL15 and RPL18 was closely associated with aortic valve calcification, which provided valuable clues to find therapeutic targets for CAVD.

Hypoxia-inducible factor activation promotes osteogenic transition of valve interstitial cells and accelerates aortic valve calcification in a mice model of chronic kidney disease

Introduction

Valve calcification (VC) is a widespread complication in chronic kidney disease (CKD) patients. VC is an active process with the involvement of in situ osteogenic transition of valve interstitial cells (VICs). VC is accompanied by the activation of hypoxia inducible factor (HIF) pathway, but the role of HIF activation in the calcification process remains undiscovered.

Methods and result

Using in vitro and in vivo approaches we addressed the role of HIF activation in osteogenic transition of VICs and CKD-associated VC. Elevation of osteogenic (Runx2, Sox9) and HIF activation markers (HIF-1α and HIF-2α) and VC occurred in adenine-induced CKD mice. High phosphate (Pi) induced upregulation of osteogenic (Runx2, alkaline-phosphatase, Sox9, osteocalcin) and hypoxia markers (HIF-1α, HIF-2α, Glut-1), and calcification in VICs. Down-regulation of HIF-1α and HIF-2α inhibited, whereas further activation of HIF pathway by hypoxic exposure (1% O₂) or hypoxia mimetics [desferrioxamine, CoCl₂, Daprodustat (DPD)] promoted Pi-induced calcification of VICs. Pi augmented the formation of reactive oxygen species (ROS) and decreased viability of VICs, whose effects were further exacerbated by hypoxia. N-acetyl cysteine inhibited Pi-induced ROS production, cell death and calcification under both normoxic and hypoxic conditions. DPD treatment corrected anemia but promoted aortic VC in the CKD mice model.

Discussion

HIF activation plays a fundamental role in Pi-induced osteogenic transition of VICs and CKD-induced VC. The cellular mechanism involves stabilization of HIF-1α and HIF-2α, increased ROS production and cell death. Targeting the HIF pathways may thus be investigated as a therapeutic approach to attenuate aortic VC.

The first taxonomic and functional characterization of human CAVD-associated microbiota

Introduction

Calcific aortic valve disease (CAVD) is the most common heart valve disorder, defined by a remodeling multistep process: namely, valve fibrosis with its area narrowing, impaired blood flow, and final calcification phase. Nowadays, the only treatment is the surgical valve replacement. As for other cardiovascular diseases, growing evidence suggest an active role of the immune system in the calcification process that could be modulated by the microbiota. To address this point, we aimed to investigate and characterize, for the first time, the presence of a valve microbiota and associated immune response in human CAVD.

Method

Calcified aortic valve (CAV) samples from twenty patients (11 from Germany and 9 from Italy) with diagnosis of severe symptomatic CAVD were used to assess the presence of infiltrating T cells, by cloning approach, and to characterize the valve microbiota, by 16S rRNA gene sequencing (NGS).

Results

We documented the presence of infiltrating T lymphocytes, especially the T helper subset, in CAV samples. Moreover, we found a tissue-associated microbiota in freshly collected CAV samples, which was significantly different in Italian and German patients, suggesting potential correlation with other cardiovascular risk factors.

Conclusion

The presence of microbiota in inflamed CAV samples represents the right trigger point to explain the valve calcification process, encouraging further studies to explore the potential link between bacteria and adaptive immune response and to define the critical role of local microbiota-immunity axis on CAVD development.

Tri-Layered and Gel-Like Nanofibrous Scaffolds with Anisotropic Features for Engineering Heart Valve Leaflets

3D heterogeneous and anisotropic scaffolds that approximate native heart valve tissues are indispensable for the successful construction of tissue engineered heart valves (TEHVs). In this study, novel tri-layered and gel-like nanofibrous scaffolds, consisting of poly(lactic-co-glycolic) acid (PLGA) and poly(aspartic acid) (PASP), are fabricated by a combination of positive/negative conjugate electrospinning and bioactive hydrogel post-processing. The nanofibrous PLGA-PASP scaffolds present tri-layered structures, resulting in anisotropic mechanical properties that are comparable with native heart valve leaflets. Biological tests show that nanofibrous PLGA-PASP scaffolds with high PASP ratios significantly promote the proliferation and collagen and glycosaminoglycans (GAGs) secretions of human aortic valvular interstitial cells (HAVICs), compared to PLGA scaffolds. Importantly, the nanofibrous PLGA-PASP scaffolds are found to effectively inhibit the osteogenic differentiation of HAVICs. Two types of porcine VICs, from young and adult age groups, are further seeded onto the PLGA-PASP scaffolds. The adult VICs secrete higher amounts of collagens and GAGs and undergo a significantly higher level of osteogenic differentiation than young VICs. RNA sequencing analysis indicates that age has a pivotal effect on the VIC behaviors. This study provides important guidance and a reference for the design and development of 3D tri-layered, gel-like nanofibrous PLGA-PASP scaffolds for TEHV applications.

Calcium-Dependent Cytosolic Phospholipase A2α as Key Factor in Calcification of Subdermally Implanted Aortic Valve Leaflets

Calcium-dependent cytosolic phospholipase A2α (cPLA2α) had been previously found to be overexpressed by aortic valve interstitial cells (AVICs) subjected to in vitro calcific induction. Here, cPLA2α expression was immunohistochemically assayed in porcine aortic valve leaflets (iAVLs) that had undergone accelerated calcification subsequent to 2- to 28-day-long implantation in rat subcutis. A time-dependent increase in cPLA2α-positive AVICs paralleled mineralization progression depending on dramatic cell membrane degeneration with the release of hydroxyapatite-nucleating acidic lipid material, as revealed by immunogold particles decorating organelle membranes in 2d-iAVLs, as well as membrane-derived lipid byproducts in 7d- to 28d-iAVLs. Additional positivity was detected for (i) pro-inflammatory IL-6, mostly exhibited by rat peri-implant cells surrounding 14d- and 28d-iAVLs; (ii) calcium-binding osteopontin, with time-dependent increase and no ossification occurrence; (iii) anti-calcific fetuin-A, mostly restricted to blood plasma within vessels irrorating the connective envelopes of 28d-iAVLs; (iv) early apoptosis marker annexin-V, limited to sporadic AVICs in all iAVLs. No positivity was found for either apoptosis executioner cleaved caspase-3 or autophagy marker MAP1. In conclusion, cPLA2α appears to be a factor characterizing AVL calcification concurrently with a distinct still uncoded cell death form also in an animal model, as well as a putative target for the prevention and treatment of calcific valve diseases.

Morphological study of the spectrum of lesions encountered in the heart and coronaries on autopsy

BACKGROUND AND OBJECTIVES

This research study has been carried out to study the various morphological changes in the heart in medicolegal autopsies and to compile data for the frequency of heart diseases found in autopsy cases.

METHODS

The present study comprised 430 medicolegal autopsy cases. Details of the cases were entered in a proforma prepared for the study. The heart was fixed in 10% formalin, and then, opened along the flow of blood. The findings were based on gross and microscopic examinations.

RESULTS

Out of 430 adult hearts, 211 (49.0%) cases showed 253 cardiac lesions; 35 (8.1%) cases of coronary atherosclerosis and 196 (45.5%) aortic atherosclerosis were noted; 7 cases of ischemic lesions (1.6%) were identified; 12 (2.7%) cases of hypertrophy; 2 cases of valve calcification; and 1 of cardiomyopathy were noted.

CONCLUSION

In the present study, among medicolegal autopsies, atherosclerotic disease was the most frequently encountered lesion followed by hypertrophy. The incidence of atherosclerosis was found to be 47.6%. This study shows the high prevalence of atherosclerosis in the population.

Heme-Mediated Activation of the Nrf2/HO-1 Axis Attenuates Calcification of Valve Interstitial Cells

Calcific aortic valve stenosis (CAVS) is a heart disease characterized by the progressive fibro-calcific remodeling of the aortic valves, an actively regulated process with the involvement of the reactive oxygen species-mediated differentiation of valvular interstitial cells (VICs) into osteoblast-like cells. Nuclear factor erythroid 2-related factor 2 (Nrf2) regulates the expression of a variety of antioxidant genes, and plays a protective role in valve calcification. Heme oxygenase-1 (HO-1), an Nrf2-target gene, is upregulated in human calcified aortic valves. Therefore, we investigated the effect of Nrf2/HO-1 axis in VIC calcification. We induced osteogenic differentiation of human VICs with elevated phosphate and calcium-containing osteogenic medium (OM) in the presence of heme. Heme inhibited Ca deposition and OM-induced increase in alkaline phosphatase and osteocalcin (OCN) expression. Heme induced Nrf2 and HO-1 expression in VICs. Heme lost its anti-calcification potential when we blocked transcriptional activity Nrf2 or enzyme activity of HO-1. The heme catabolism products bilirubin, carbon monoxide, and iron, and also ferritin inhibited OM-induced Ca deposition and OCN expression in VICs. This study suggests that heme-mediated activation of the Nrf2/HO-1 pathway inhibits the calcification of VICs. The anti-calcification effect of heme is attributed to the end products of HO-1-catalyzed heme degradation and ferritin.

Collagen networks within 3D PEG hydrogels support valvular interstitial cell matrix mineralization

Enzymatically degradable hydrogels were designed for the 3D culture of valvular interstitial cells (VICs), and through the incorporation of various functionalities, we aimed to investigate the role of the tissue microenvironment in promoting the osteogenic properties of VICs and matrix mineralization. Specifically, porcine VICs were encapsulated in a poly(ethylene glycol) hydrogel crosslinked with a matrix metalloproteinase (MMP)-degradable crosslinker (KCGPQG↓IWGQCK) and formed via a thiol-ene photoclick reaction in the presence or absence of collagen type I to promote matrix mineralization. VIC-laden hydrogels were treated with osteogenic medium for up to 15 days, and the osteogenic response was characterized by the expression of RUNX2 as an early marker of an osteoblast-like phenotype, osteocalcin (OCN) as a marker of a mature osteoblast-like phenotype, and vimentin (VIM) as a marker of the fibroblast phenotype. In addition, matrix mineralization was characterized histologically with Von Kossa stain for calcium phosphate. Osteogenic response was further characterized biochemically with calcium assays, and physically via optical density measurements. When the osteogenic medium was supplemented with calcium chloride, OCN expression was upregulated and mineralization was discernable at 12 days of culture. Finally, this platform was used to screen various drug therapeutics that were assessed for their efficacy in preventing mineralization using optical density as a higher throughput readout. Collectively, these results suggest that matrix composition has a key role in supporting mineralization deposition within diseased valve tissue.

The relationship between plasma vitamin D level and heart valves calcification in acute coronary syndrome and non acute coronary syndrome patients

Background

There is conflicting data regarding the association between low levels of plasma vitamin D and ischemic heart disease. We aimed to investigate the relationship between plasma vitamin D levels and heart valve calcification in hospitalized patients with ischemic heart disease versus non-ischemic heart disease controls.

Methods

A prospective case-control study comprising two age and gender-matched groups. The study group included consecutive patients hospitalized due to acute coronary syndrome; the control group included consecutive non-ischemic heart disease patients hospitalized for noncardiac causes. Blood samples for 25-hydroxyvitamin D level were drawn. An echocardiogram was performed during the first 3 days of hospitalization and reviewed for presence and degree of valvular calcification.

Results

Forty patients with acute coronary syndrome and 40 controls (age 58 ± 11 years, 64% male in both groups) were included. Mean plasma 25-hydroxyvitamin D vitamin level in the entire cohort was 24.5 ± 8 ng/ml. Valve calcification rates were similar in acute coronary syndrome versus non-acute coronary syndrome group (28 vs. 21 had valvular calcification; 18 vs. 12 had aortic valve calcification; 21 vs. 14 had mitral valve calcification, respectively; P = NS for all). We found no significant relationship between vitamin D level and valvular calcification, aortic valve calcification, or mitral valve calcification rate or degree in the entire cohort and in each group alone (P = NS for all). There was a negative correlation between 25-hydroxyvitamin D levels and age in the acute coronary syndrome group (r = -0.399, P = 0.012).

Conclusions

We did not find a significant relationship between plasma vitamin D levels and the rate or degree of calcification of either aortic/mitral/both valves in hospitalized patients with or without ischemic heart disease.

Inflammation and Mechanical Stress Stimulate Osteogenic Differentiation of Human Aortic Valve Interstitial Cells

Background: Aortic valve calcification is an active proliferative process, where interstitial cells of the valve transform into either myofibroblasts or osteoblast-like cells causing valve deformation, thickening of cusps and finally stenosis. This process may be triggered by several factors including inflammation, mechanical stress or interaction of cells with certain components of extracellular matrix. The matrix is different on the two sides of the valve leaflets. We hypothesize that inflammation and mechanical stress stimulate osteogenic differentiation of human aortic valve interstitial cells (VICs) and this may depend on the side of the leaflet. Methods: Interstitial cells isolated from healthy and calcified human aortic valves were cultured on collagen or elastin coated plates with flexible bottoms, simulating the matrix on the aortic and ventricular side of the valve leaflets, respectively. The cells were subjected to 10% stretch at 1 Hz (FlexCell bioreactor) or treated with 0.1 μg/ml lipopolysaccharide, or both during 24 h. Gene expression of myofibroblast- and osteoblast-specific genes was analyzed by qPCR. VICs cultured in presence of osteogenic medium together with lipopolysaccharide, 10% stretch or both for 14 days were stained for calcification using Alizarin Red. Results: Treatment with lipopolysaccharide increased expression of osteogenic gene bone morphogenetic protein 2 (BMP2) (5-fold increase from control; p = 0.02) and decreased expression of mRNA of myofibroblastic markers: α-smooth muscle actin (ACTA2) (50% reduction from control; p = 0.0006) and calponin (CNN1) (80% reduction from control; p = 0.0001) when cells from calcified valves were cultured on collagen, but not on elastin. Mechanical stretch of VICs cultured on collagen augmented the effect of lipopolysaccharide. Expression of periostin (POSTN) was inhibited in cells from calcified donors after treatment with lipopolysaccharide on collagen (70% reduction from control, p = 0.001), but not on elastin. Lipopolysaccharide and stretch both enhanced the pro-calcific effect of osteogenic medium, further increasing the effect when combined for cells cultured on collagen, but not on elastin. Conclusion: Inflammation and mechanical stress trigger expression of osteogenic genes in VICs in a side-specific manner, while inhibiting the myofibroblastic pathway. Stretch and lipopolysaccharide synergistically increase calcification.

Associations of Mitral and Aortic Valve Calcifications with Complex Aortic Atheroma in Patients with Embolic Stroke of Undetermined Source

BACKGROUND

This study investigated the associations of mitral and aortic valve calcification with complex aortic atheroma among patients with embolic stroke of undetermined source.

METHODS

We included 52 consecutive patients (mean age 58.1 years; 75.0% male) with embolic stroke of undetermined source. Mitral annular calcification, aortic annular calcification, and aortic valve sclerosis were assessed by transthoracic echocardiography. Complex aortic atheroma was assessed by transesophageal echocardiography and was defined as plaque protruding greater than or equal to 4 mm into the lumen or with ulcerated or mobile components.

RESULTS

Ten patients (19.2%) had complex aortic atheroma. Patients with and without complex aortic atheroma showed significant differences in terms of hypertension (80.0% versus 38.1%, P = .017), dyslipidemia (90.0% versus 31.0%, P <.01), chronic kidney disease (60.0% versus 14.3%, P <.01), previous coronary artery disease (30.0% versus 4.8%, P = .013), prior stroke (40.0% versus 7.1%, P <.01), left atrial dimension (4.0 cm versus 3.6 cm, P = .023), aortic valve sclerosis (80.0% versus 26.2%, P <.01), aortic valve calcification (aortic annular calcification or aortic valve sclerosis) (80.0% versus 26.0%, P <.01), and left-sided valve calcification (mitral annular calcification or aortic annular calcification or aortic valve sclerosis) (80.0% versus 28.6%, P <.01). In multivariate analysis, left-sided valve calcification was independently associated with complex aortic atheroma (odds ratio 4.1, 95% confidence interval 1.3-26.1, P = .049).

CONCLUSIONS

Mitral or aortic valve calcification detected by transthoracic echocardiography can be a useful marker for predicting complex aortic atheroma in patients with embolic stroke of undetermined source.

Classification of Aortic Stenosis by Flow and Gradient Patterns Provides Insights into the Pathophysiology of Disease

Different patterns of flow and valve gradients can lead to diagnostic uncertainty about the severity of aortic stenosis (AS). Consecutive patients with severe AS (valve area <1 cm(2)) underwent echocardiography and computed tomography. Patients were classified into 4 groups (high-gradient/normal flow [HGNF], high-gradient/low flow [HGLF], low-gradient/normal flow [LGNF], and low-gradient/low flow [LGLF]). Low flow was defined as stroke volume index <35 mL/m(2) and low gradient as a mean aortic gradient <40 mm Hg. Aortic valve calcification (AVC) was calculated using the Agatston score. Of 181 patients, 56, 30, 46, and 49 had HGNF, HGLF, LGNF and LGLF with median AVC of 2048, 2015, 1366, and 1178 AU/m(2) (P < .0001) and valvuloarterial impedance of 4.5, 6.4, 4.2, and 5.9, respectively (P < .0001). Among those with LGLF, AVC was lower in patients with preserved compared to reduced left ventricular ejection fraction (1018 vs 2550 AU/m(2); P < .0001), but valvuloarterial impedance was similar (P = .33). The LGLF AS with preserved ejection fraction is associated with lower AVC and may identify patients with less severe AS in association with an adaptive ventricular response to high afterload.