Hemodynamic Analysis of Non-uniformly Calcified Aortic Valve Using a Partitioned Fluid-Structure Interaction Framework.

Received October 26, 2004; revision received January 13, 2005; accepted February 4, 2005. Calcific aortic valve disease is a slowly progressive disorder with a disease continuum that ranges from mild valve thickening without obstruction of blood flow, termed aortic sclerosis, to severe calcification with impaired leaflet motion, or aortic stenosis (Figure 1). In the past, this process was thought to be “degenerative” because of time-dependent wear-and-tear of the leaflets with passive calcium deposition. Now, there is compelling histopathologic and clinical data suggesting that calcific valve disease is an active disease process akin to atherosclerosis with lipoprotein deposition, chronic inflammation, and active leaflet calcification. The overlap in the clinical factors associated with calcific valve disease and atherosclerosis and the correlation between the severity of coronary artery and aortic valve calcification provide further support for a shared disease process. Figure 1. Gross specimen of minimally diseased aortic valve (left) and severely stenotic aortic valve (right). In the severely stenotic valve, there are prominent lipocalcific changes on aortic side of valve cusps (arrow), with sparing of commissures. ### Anatomy of Normal Aortic Valve The normal aortic valve comprises 3 layers. The ventricularis, on the ventricular side of the leaflet, is composed of elastin-rich fibers that are aligned in a radial direction, perpendicular to the leaflet margin. The fibrosa, on the aortic side of the leaflet, comprises primarily fibroblasts and collagen fibers arranged circumferentially, parallel to the leaflet margin. The spongiosa is a layer of loose connective tissue at the base of the leaflet, between the fibrosa and ventricularis, composed of fibroblasts, mesenchymal cells, and a mucopolysaccharide-rich matrix. These layers work in concert to provide tensile strength and pliability for decades of repetitive motion. ### Early Lesion of Aortic Sclerosis Histopathologic studies of aortic sclerosis show focal subendothelial plaquelike lesions on the aortic side of the leaflet that extend to the adjacent fibrosa layer. Similarities to …

Prosthesis–patient mismatch and clinical outcomes: The evidence continues to accumulate

035 Lipoprotein Lipase Expression is Associated With Calcific Aortic Valve Disease: Interaction With the Size of HDL

Transcatheter aortic valve replacement valve-in-valve: Future implications for the surgeon

Calcification and Thrombosis as Mediators of Bioprosthetic Valve Deterioration

Alterations in lipid metabolism and inflammatory processes are well established as potential risk factors in the development and progression of cardiovascular disease.1 However, with complications ranging from valve dysfunction to arrhythmia to myocardial infarction and stroke, the underlying mechanisms may be as varied as cardiovascular disease itself. On the other hand, the reoccurrence of common molecular and cellular pathways identified in the collective body of cardiovascular research could suggest shared initiators or mechanistic nodes between seemingly divergent processes, including lipid metabolism and inflammation. One area where this may hold true is cardiovascular calcification, in which dysregulated mineral metabolism in cardiovascular tissues leads to increased morbidity and mortality. Article see p 677 Calcification of soft tissues results from the deposition of calcium, largely in the form of hydroxyapatite, in the vascular wall or valve leaflets. Previously thought to be a passive degenerative process, it has become increasingly apparent that cardiovascular calcification is an active process initiated by many triggers. Recent studies have demonstrated variation in the LPA gene, which determines the plasma concentration of lipoprotein(a) [Lp(a); pronounced “L P little a”] to be associated with calcific aortic valve disease (CAVD).2,3 Lp(a) consists of a low-density lipoprotein (LDL)–like particle in which apolipoprotein(a) is covalently bound to apolipoprotein B. Additionally, Lp(a) is a genetic risk factor for atherosclerotic events.4 As in atherosclerosis, calcifications in CAVD localize to areas with lipoprotein accumulation and inflammatory cell infiltration, suggesting a shared disease process.5 However, some noticeable differences exist, including increased mechanical stresses and calcification-involved valve obstruction in CAVD as opposed to microcalcifications leading atherosclerosis plaque rupture.6 In this issue of Circulation , Bouchareb et al7 propose a highly plausible mechanistic pathway through which Lp(a) and valve interstitial cell (VIC)–derived autotaxin may induce valve calcification by regulating inflammation-induced bone …

The morbidity and death rates of calcified aortic valves|calcific aortic valve (CAV) disease (CAVD) remain high for its limited therapeutic choices. Here, we investigated the function, therapeutic potential, and putative mechanisms of Enoyl coenzyme A hydratase 1 (ECH1) in CAVD by various in vitro and in vivo experiments. Single-cell sequencing revealed that ECH1 was predominantly expressed in valve interstitial cells and was significantly reduced in CAVs. Overexpression of ECH1 reduced aortic valve calcification in ApoE-/- mice treated with high cholesterol diet, while ECH1 silencing had the reverse effect. We also identified Wnt5a, a noncanonical Wnt ligand, was also altered when ECH1 expression was modulated. Mechanistically, we found that ECH1 exerted anti-calcific actions through suppressing Wnt signaling, since CHIR99021, a Wnt agonist, may significantly lessen the protective impact of ECH1 overexpression on the development of valve calcification. ChIP and luciferase assays all showed that ECH1 overexpression prevented Runx2 binding to its downstream gene promoters (osteopontin and osteocalcin), while CHIR99021 neutralized this protective effect. Collectively, our findings reveal a previously unrecognized mechanism of ECH1-Wnt5a/Ca2+ regulation in CAVD, implying that targeting ECH1 may be a potential therapeutic strategy to prevent CAVD development.

The bicuspid aortic valve (BAV) is the most common congenital cardiac anomaly and is present in 2% of the population. While a normal tricuspid aortic valve (TAV) consists of three leaflets, a BAV is formed with only two as a result of the fusion of two leaflets into a larger one1. This defect is associated with serious complications such as calcific aortic valve disease (CAVD), a condition characterized by the accumulation of calcium on the leaflets which contributes to the obstruction of the left ventricular outflow and progressive heart failure. Although studies have suggested similarities in the pathogenesis of CAVD in the BAV and TAV, the calcification of the BAV is more severe and its progression more rapid. Previous studies in our laboratory have evidenced the sensitivity of valve leaflets to their hemodynamic environment and the ability of fluid stress alterations to trigger an inflammatory response on the aortic surface of porcine aortic valve leaflets2. Although a similar mechano-etiology could contribute to the rapid calcification of the BAV, it is not clear how the particular BAV anatomy impacts on its hemodynamic environment and whether the hemodynamic stresses experienced by BAV leaflets differ from those present in TAV leaflets. Therefore, the aim of this study was to characterize BAV hemodynamics and to quantify its degree of abnormality relative to a TAV. A fluid-structure interaction (FSI) approach validated with respect to particle-image velocimetry (PIV) measurements was implemented to quantify TAV and BAV hemodynamics in terms of flow velocity field, valvular effective orifice area (EOA) and leaflet wall-shear stress. The large degree of hemodynamic abnormality predicted in the BAV model may contribute to the rapid progression of CAVD in that anatomy. This work lays the foundation for future mechanobiological studies aimed at investigating the isolated effects of native BAV hemodynamic stresses on the development of CAVD.

Aortic valve (AV) stenosis is one of the most common valvular diseases and is the third most common cardiovascular disease in developed countries. It occurs in ≈2.8% of patients ≥75 years of age and can occur because of degenerative calcification and congenital valvular defects such as bicuspid AVs or rheumatic disease.1–3 Calcific aortic stenosis (AS) is associated with increased leaflet stiffness and a narrowed AV orifice, resulting in increased pressure gradients across the valve. The presence of a bicuspid AV significantly increases the risk of AS.4 The natural history of AS is a prolonged asymptomatic period, with progressive reduction of the AV orifice area due to sclerosis initially, culminating in calcific AS. This is accompanied by a corresponding increase in the transaortic pressure gradient (Δ P ) and myocardial pressure overload. Through the preload reserve, the left ventricle (LV) compensates for the increased workload until the sarcomeres stretch to their maximum diastolic length. Once the preload reserve is exhausted, increases in afterload are accompanied by a reduction in stroke volume (SV), resulting in afterload mismatch. Ultimately, this causes LV hypertrophy, associated with an enlargement of cardiac myocytes and increased LV wall thickness.5 Initial diagnosis of AS typically occurs during routine physical examination with the presence of a heart murmur, click, or other abnormal sounds, but undiagnosed patients may experience the onset of severe symptoms such as angina, syncope, and heart failure. Without intervention, patient mortality typically occurs within 5 years of the onset of symptoms.6–11 Multiple studies and reviews have focused on the clinical aspects of this disease, including disease progression, markers of disease severity, treatment guidelines, and outcomes.1–3,6,12–16 Very few reviews have focused on the hemodynamic principles underlying AS and on comparing data obtained across different …

Analysis of Osteopontin Levels for the Identification of Asymptomatic Patients With Calcific Aortic Valve Disease

Sex-differences in echocardiographic assessment of aortic valve in young adult LDLr-/-/ApoB100/100/IGF-II+/- mice.

Calcific aortic valve disease (CAVD) is common in people over the age of 65. Progressive valvular calcification is a characteristic of CAVD and due to chronic inflammation in aortic valve interstitial cells (AVICs) resulting in CAVD progression. IL-38 is a naturally occurring anti-inflammatory cytokine; here, we report lower levels of endogenous IL-38 in AVICs isolated from patients' CAVD valves compared to AVICs from non-CAVD valves. Recombinant IL-38 suppressed spontaneous inflammatory activity and calcium deposition in cultured AVICs. In mice, knockdown of IL-38 enhanced the production of inflammatory mediators in murine AVICs exposed to the proinflammatory stimulant matrilin-2. We also observed that in cultured AVICs matrilin-2 stimulation activated the NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome with procaspase-1 cleavage into active caspase-1. The addition of IL-38 to matrilin-2-treated AVICs suppressed caspase-1 activation and reduced the expression of intercellular adhesion molecule-1, vascular cell adhesion molecule-1, runt-related transcription factor 2, and alkaline phosphatase. Aged IL-38-deficient mice fed a high-fat diet exhibited aortic valve lesions compared to aged wild-type mice fed the same diet. The interleukin-1 receptor 9 (IL-1R9) is the putative receptor mediating the anti-inflammatory properties of IL-38; we observed that IL-1R9-deficient mice exhibited spontaneous aortic valve thickening and greater calcium deposition in AVICs compared to wild-type mice. These data demonstrate that IL-38 suppresses spontaneous and stimulated osteogenic activity in aortic valve via inhibition of the NLRP3 inflammasome and caspase-1. The findings of this study suggest that IL-38 has therapeutic potential for prevention of CAVD progression.

Calcific Aortic Valve Disease (CAVD) affects >2% of the population over the age of 65, for whom the current standard of care is valve replacement surgery. To date, there are no pharmacologic-based therapies that prevent the progression or inhibit the development of CAVD, thus highlighting the necessity for new therapeutic approaches. Despite its clinical significance, the pathogenic mechanisms that drive the development of CAVD, and that could serve as potential therapeutic targets, remain unknown. We have recently identified Klotho-deficient mice, an established model of premature aging, as a novel model of CAVD that exhibit aortic valve calcification on the fibrosa side of the hinge region, closely mimicking human CAVD pathology. Unlike previous models, calcification occurs independent of inflammation and valve thickening in these mice, supporting a distinct mechanism of age-related calcification common in elderly patients. In bone, BMP-mediated osteogenic gene induction is essential for the process of calcification. Notably, pSmad1/5/8 activation, indicative of active BMP signaling, is observed prior to the onset of calcification and later is localized with calcific nodule formation in klotho-deficient mice with CAVD. Our hypothesis is that activation of BMP-pSmad1/5/8 signaling pathway promotes osteogenic gene induction and aortic valve mineralization in CAVD. Osteogenic factors, Runx2 and Osteopontin, are significantly increased in the aortic valves of klotho-deficient mice, suggesting an osteogenic-like mechanism of disease. Likewise, pSmad1/5/8 activation precedes osteogenic gene induction in these mice. Moreover, increased BMP2/4 ligand expression is detected prior to the onset of disease, as well as during calcific nodule formation, thus supporting an active role for the BMP-pSmad1/5/8 signaling cascade during aortic valve calcification. Our ongoing work includes BMP pathway inhibition studies to determine if this is an effective therapeutic strategy for the treatment of CAVD in the klotho-deficient mice. Altogether our data support a role for the BMP-pSmad1/5/8 signaling cascade as a critical mechanism in the initial onset and progression of aortic valve calcification in a novel mouse model of CAVD.

Background: Calcific aortic valve disease (CAVD) is the most common valvular heart disease in the aging population, resulting in a significant health and economic burden worldwide, but its underlying diagnostic biomarkers and pathophysiological mechanisms are not fully understood. Methods: Three publicly available gene expression profiles (GSE12644, GSE51472, and GSE77287) from human Calcific aortic valve disease (CAVD) and normal aortic valve samples were downloaded from the Gene Expression Omnibus database for combined analysis. R software was used to identify differentially expressed genes (DEGs) and conduct functional investigations. Two machine learning algorithms, least absolute shrinkage and selection operator (LASSO) and support vector machine-recursive feature elimination (SVM-RFE), were applied to identify key feature genes as potential biomarkers for Calcific aortic valve disease (CAVD). Receiver operating characteristic (ROC) curves were used to evaluate the discriminatory ability of key genes. The CIBERSORT deconvolution algorithm was used to determine differential immune cell infiltration and the relationship between key genes and immune cell types. Finally, the Expression level and diagnostic ability of the identified biomarkers were further validated in an external dataset (GSE83453), a single-cell sequencing dataset (SRP222100), and immunohistochemical staining of human clinical tissue samples, respectively. Results: In total, 34 identified DEGs included 21 upregulated and 13 downregulated genes. DEGs were mainly involved in immune-related pathways such as leukocyte migration, granulocyte chemotaxis, cytokine activity, and IL-17 signaling. The machine learning algorithm identified SCG2 and CCL19 as key feature genes [area under the ROC curve (AUC) = 0.940 and 0.913, respectively; validation AUC = 0.917 and 0.903, respectively]. CIBERSORT analysis indicated that the proportion of immune cells in Calcific aortic valve disease (CAVD) was different from that in normal aortic valve tissues, specifically M2 and M0 macrophages. Key genes SCG2 and CCL19 were significantly positively correlated with M0 macrophages. Single-cell sequencing analysis and immunohistochemical staining of human aortic valve tissue samples showed that SCG2 and CCL19 were increased in Calcific aortic valve disease (CAVD) valves. Conclusion: SCG2 and CCL19 are potential novel biomarkers of Calcific aortic valve disease (CAVD) and may play important roles in the biological process of Calcific aortic valve disease (CAVD). Our findings advance understanding of the underlying mechanisms of Calcific aortic valve disease (CAVD) pathogenesis and provide valuable information for future research into novel diagnostic and immunotherapeutic targets for Calcific aortic valve disease (CAVD).

Calcific aortic valve disease (CAVD) is the result of maladaptive fibrocalcific processes leading to a progressive thickening and stiffening of aortic valve (AV) leaflets. CAVD is the most common cause of aortic stenosis (AS). At present, there is no effective pharmacotherapy in reducing CAVD progression; when CAVD becomes symptomatic it can only be treated with valve replacement. Inflammation has a key role in AV pathological remodeling; hence, anti-inflammatory therapy has been proposed as a strategy to prevent CAVD. Cyclooxygenase 2 (COX-2) is a key mediator of the inflammation and it is the target of widely used anti-inflammatory drugs. COX-2-inhibitor celecoxib was initially shown to reduce AV calcification in a murine model. However, in contrast to these findings, a recent retrospective clinical analysis found an association between AS and celecoxib use. In the present study, we investigated whether variations in COX-2 expression levels in human AVs may be linked to CAVD. We extracted total RNA from surgically explanted AVs from patients without CAVD or with CAVD. We found that COX-2 mRNA was higher in non-calcific AVs compared to calcific AVs (0.013 ± 0.002 vs. 0.006 ± 0.0004; p < 0.0001). Moreover, we isolated human aortic valve interstitial cells (AVICs) from AVs and found that COX-2 expression is decreased in AVICs from calcific valves compared to AVICs from non-calcific AVs. Furthermore, we observed that COX-2 inhibition with celecoxib induces AVICs trans-differentiation towards a myofibroblast phenotype, and increases the levels of TGF-β-induced apoptosis, both processes able to promote the formation of calcific nodules. We conclude that reduced COX-2 expression is a characteristic of human AVICs prone to calcification and that COX-2 inhibition may promote aortic valve calcification. Our findings support the notion that celecoxib may facilitate CAVD progression.