Aortic valve stenosis: an active atheroinflammatory process

PURPOSE OF REVIEW: To summarize the current understanding of the pathobiology of aortic valve stenosis and portray the major advances in this field. RECENT FINDINGS: Stenotic aortic valves are characterized by atherosclerosis-like lesions, consisting of activated inflammatory cells, including T lymphocytes, macrophages, and mast cells, and of lipid deposits, calcific nodules, and bone tissue. Active mediators of calcification and cells with osteoblast-like activity are present in diseased valves. Extracellular matrix remodeling, including collagen synthesis and elastin degradation by matrix metalloproteinases and cathepsins, contributes to leaflet stiffening. In experimental animals, hypercholesterolemia induces calcification and bone formation in aortic valves, which can be inhibited by statin treatment. The potential of statins to retard progression of aortic valve stenosis has also been recognized in clinical studies; however, further prospective trials are needed. Angiotensin II-forming enzymes are upregulated in stenotic valves. Angiotensin II may participate in profibrotic progression of aortic valve stenosis and may serve as a possible therapeutic target. SUMMARY: Recent findings regarding the interaction of inflammatory cells, lipids, mediators of calcification, and renin-angiotensin system in stenotic valves support the current opinion of aortic valve stenosis being an actively regulated disease, potentially amenable to targeted molecular therapy. Evidence from prospective clinical studies is eagerly awaited.     

Modified Lipoprotein-Derived Lipid Particles Accumulate in Human Stenotic Aortic Valves

In aortic stenosis plasma lipoprotein-derived lipids accumulate in aortic valves. Here, we first compared the lipid compositions of stenotic aortic valves and atherosclerotic plaque cores. Both pathological tissues were found to be enriched in cholesteryl linoleate, a marker of extracellularly accumulated lipoproteins. In addition, a large proportion of the phospholipids were found to contain arachidonic acid, the common precursor of a number of proinflammatory lipid mediators. Next, we isolated and characterized extracellular lipid particles from human stenotic and non-stenotic control valves, and compared them to plasma lipoproteins from the same subjects. The extracellular valvular lipid particles were isolated from 15 stenotic and 14 non-stenotic aortic valves. Significantly more apoB-100-containing lipid particles were found in the stenotic than in the non-stenotic valves. The majority of the lipid particles isolated from the non-stenotic valves had sizes (23±6.2 nm in diameter) similar to those of plasma low density lipoprotein (LDL) (22±1.5 nm), while the lipid particles from stenotic valves were not of uniform size, their sizes ranging from 18 to more than 500 nm. The lipid particles showed signs of oxidative modifications, and when compared to isolated plasma LDL particles, the lipid particles isolated from the stenotic valves had a higher sphingomyelin/phosphatidylcholine –ratio, and also higher contents of lysophosphatidylcholine and unesterified cholesterol. The findings of the present study reveal, for the first time, that in stenotic human aortic valves, infiltrated plasma lipoproteins have undergone oxidative and lipolytic modifications, and become fused and aggregated. The generated large lipid particles may contribute to the pathogenesis of human aortic stenosis.     

Hyperlipidaemia and aortic valve disease

PURPOSE OF REVIEW: Degenerative aortic valve stenosis is a common disease in the elderly, and traditional risk factors for atherosclerotic disease including hyperlipidaemia have been associated with the condition in several studies. This review addresses the role of the various risk factors and the potential for intervention. RECENT FINDINGS: The association of lipid abnormalities such as high lipoprotein(a) levels and the presence of the apolipoprotein E4 allele with aortic stenosis, as well as the presence of several inflammatory markers both in plasma and in surgically excised valves, suggest that the stenotic process is driven by many of the same factors behind atherosclerosis. The aortic valves of animals fed a cholesterol-rich diet exhibit many characteristics in common with the early stages of aortic stenosis. This opens up the potential of retarding the process through intervention strategies. SUMMARY: Hyperlipidaemia is associated with degenerative aortic valve stenosis, and the disease resembles the inflammatory process of atherosclerosis. Randomized controlled clinical trials will be needed to demonstrate the role of lipid intervention in patients with this condition.     

Synergy between Sphingosine 1-Phosphate and Lipopolysaccharide Signaling Promotes an Inflammatory,Angiogenic and Osteogenic Response in Human Aortic Valve Interstitial Cells

Given that the bioactive lipid sphingosine 1-phosphate is involved in cardiovascular pathophysiology, and since lipid accumulation and inflammation are hallmarks of calcific aortic stenosis, the role of sphingosine 1-phosphate on the pro-inflammatory/pro-osteogenic pathways in human interstitial cells from aortic and pulmonary valves was investigated. Real-time PCR showed sphingosine 1-phosphate receptor expression in aortic valve interstitial cells. Exposure of cells to sphingosine 1-phosphate induced pro-inflammatory responses characterized by interleukin-6, interleukin-8, and cyclooxygenase-2 up-regulations, as observed by ELISA and Western blot. Strikingly, cell treatment with sphingosine 1-phosphate plus lipopolysaccharide resulted in the synergistic induction of cyclooxygenase-2, and intercellular adhesion molecule 1, as well as the secretion of prostaglandin E₂, the soluble form of the intercellular adhesion molecule 1, and the pro-angiogenic factor vascular endothelial growth factor-A. Remarkably, the synergistic effect was significantly higher in aortic valve interstitial cells from stenotic than control valves, and was drastically lower in cells from pulmonary valves, which rarely undergo stenosis. siRNA and pharmacological analysis revealed the involvement of sphingosine 1-phosphate receptors 1/3 and Toll-like receptor-4, and downstream signaling through p38/MAPK, protein kinase C, and NF-κB. As regards pro-osteogenic pathways, sphingosine 1-phosphate induced calcium deposition and the expression of the calcification markers bone morphogenetic protein-2 and alkaline phosphatase, and enhanced the effect of lipopolysaccharide, an effect that was partially blocked by inhibition of sphingosine 1-phosphate receptors 3/2 signaling. In conclusion, the interplay between sphingosine 1-phosphate receptors and Toll-like receptor 4 signaling leads to a cooperative up-regulation of inflammatory, angiogenic, and osteogenic pathways in aortic valve interstitial cells that seems relevant to the pathogenesis of aortic stenosis and may allow the inception of new therapeutic approaches.     

Angiogenic activation of valvular endothelial cells in aortic valve stenosis

Here, we demonstrate the angiogenic response of valvular endothelial cells to aortic valve (AV) stenosis using a new ex vivo model of aortic leaflets. Histological analysis revealed neovascularization within the cusps of stenotic but not of non-stenotic aortic valves. Correspondingly, the number of capillary-like outgrowth in 3D collagen gel was significantly higher in stenotic than in non-stenotic valves. Capillary-like sprouting was developed significantly faster in stenotic than in non-stenotic valves. New capillary sprouts from stenotic aortic valves exhibited the endothelial cell markers CD31, CD34 and von-Willebrand factor (vWF) as well as carcinoembryonic antigen cell adhesion molecule-1 (CEACAM1), Tie-2 and angiogenesis inhibitor endostatin. Western blot analyses revealed a significant increase of CEACAM1 and endostatin in stenotic aortic valve tissue. Electron microscopic examinations demonstrate that these capillary-like tubes are formed by endothelial cells containing Weibel-Palade bodies. Remarkably, inter-endothelial junctions are established and basement membrane material is partially deposited on the basal side of the endothelial tubes. Our data demonstrate the capillary-like sprout formation from aortic valves and suggest a role of angiogenesis in the pathogenesis of aortic valve stenosis. These data provide new insights into the mechanisms of valvular disorders and open new perspectives for prevention and early treatment of calcified aortic stenosis.     

Chondromodulin-I maintains cardiac valvular function by preventing angiogenesis

The avascularity of cardiac valves is abrogated in several valvular heart diseases (VHDs). This study investigated the molecular mechanisms underlying valvular avascularity and its correlation with VHD. Chondromodulin-I, an antiangiogenic factor isolated from cartilage, is abundantly expressed in cardiac valves. Gene targeting of chondromodulin-I resulted in enhanced Vegf-A expression, angiogenesis, lipid deposition and calcification in the cardiac valves of aged mice. Echocardiography showed aortic valve thickening, calcification and turbulent flow, indicative of early changes in aortic stenosis. Conditioned medium obtained from cultured valvular interstitial cells strongly inhibited tube formation and mobilization of endothelial cells and induced their apoptosis; these effects were partially inhibited by chondromodulin-I small interfering RNA. In human VHD, including cases associated with infective endocarditis, rheumatic heart disease and atherosclerosis, VEGF-A expression, neovascularization and calcification were observed in areas of chondromodulin-I downregulation. These findings provide evidence that chondromodulin-I has a pivotal role in maintaining valvular normal function by preventing angiogenesis that may lead to VHD.     

Accumulation of cholesterol precursors and plant sterols in human stenotic aortic valves

The pathogenesis of aortic valve stenosis (AS) is characterized by the accumulation of LDL-derived cholesterol in the diseased valves. Since LDL particles also contain plant sterols, we investigated whether plant sterols accumulate in aortic valve lesions. Serum samples were collected from 82 patients with severe AS and from 12 control subjects. Aortic valves were obtained from a subpopulation of 21 AS patients undergoing valve surgery and from 10 controls. Serum and valvular total cholesterol and noncholesterol sterols were measured by gas-liquid chromatography. Noncholesterol sterols, including both cholesterol precursors and sterols reflecting cholesterol absorption, were detected in serum samples and aortic valves. The higher the ratios to cholesterol of the cholesterol precursors and absorption markers in serum, the higher their ratios in the stenotic aortic valves (r=0.74, P<0.001 for lathosterol and r=0.88, P<0.001 for campesterol). The valvular ratio to cholesterol of lathosterol correlated negatively with the aortic valve area (r= -0.47, P=0.045), suggesting attenuation of cholesterol synthesis with increasing severity of AS. The higher the absorption of cholesterol, the higher the plant sterol contents in stenotic aortic valves. These findings suggest that local accumulation of plant sterols and cholesterol precursors may participate in the pathobiology of aortic valve disease.     

Detection and imaging of lipids of <Emphasis Type="Italic">Scenedesmus obliquus</Emphasis> based on confocal Raman microspectroscopy

In this study, confocal Raman microspectroscopy was used to detect lipids in microalgae rapidly and non-destructively. Microalgae cells were cultured under nitrogen deficiency. The accumulation of lipids in Scenedesmus obliquus was observed by Nile red staining, and the total amount of lipids accumulated in the cells was measured by gravimetric method. The signals from different microalgae cells were collected by confocal Raman microspectroscopy to establish a prediction model of intracellular lipid content, and surface scanning signals for drawing pseudo color images of lipids distribution. The images can show the location of pyrenoid and lipid accumulation in cells. Analyze Raman spectrum data and build PCA-LDA model using four different bands (full bands, pigments, lipids, and mixed features). Models of full bands or pigment characteristic bands were capable of identifying S. obliquus cells under different nitrogen stress culture time. The prediction accuracy of model of lipid characteristic bands is relatively low. The correlation between the fatty acid content measured by the gravimetric method and the integral Raman intensity of the oil characteristic peak (1445 cm^?1) measured by Raman spectroscopy was analyzed. There was significant correlation (R ² = 0.83), which means that Raman spectroscopy is applicable to semi-quantitative detection of microalgal lipid content.     

Numerical simulation of steady turbulent flow through trileaflet aortic heart valves—II. Results on five models

Turbulent flow simulations are run for five aortic trileaflet valve geometries, ranging from a valve leaflet orifice area of 1.1 cm² (Model A1—very stenotic) to 5.0 cm² (Model A5—natural valve). The simulated data compares well with experimental measurements made downstream of various aortic trileaflet valves by Woo (PhD Thesis, 1984). The location and approximate width and length of recirculation regions are correctly predicted. The less stenotic valve models reattach at the end of the aortic sinus region, 1.1 diameters downstream of the valve. The central jet exiting the less stenotic valve models is not significantly different from fully developed flow, and therefore recovers very quickly downstream of the reattachment point. The more stenotic valves disturb the flow to a greater degree, generating recirculation regions large enough to escape the sinuses and reattach further downstream. Peak turbulent shear stress values downstream of the aortic valve models which approximated prosthetic valves are 125 and 300 N m⁻², very near experimental observations of 150 to 350 N m⁻². The predicted Reynolds stress profiles also present the correct shape, a double peak profile, with the location of the peak occuring at the location of maximum velocity gradient, which occurs near the recirculation region. The pressure drop across model A2 (leaflet orifice area 1.6 cm²) is 20 mmHg at 1.6 diameters downstream. This compares well with values ranging from 19.5 to 26.2 mmHg for valves of similar orifice areas. The pressure drop decreases with decreasing valve stenosis, to a negligible value across the least stenotic valve model. Based on the good agreement between experimental measurements of velocity, shear stress and pressure drop, compared to the simulated data, the model has the potential to be a valuable tool in the analysis of heart valve designs.     

A calcified polymeric valve for valve-in-valve applications

The prevalence of aortic valve stenosis (AS) is increasing in the aging society. More recently, novel treatments and devices for AS, especially transcatheter aortic valve replacement (TAVR) have significantly changed the therapeutic approach to this disease. Research and development related to TAVR require testing these devices in the calcified heart valves that closely mimic a native calcific valve. However, no animal model of AS has yet been available. Alternatively, animals with normal aortic valve that are currently used for TAVR experiments do not closely replicate the aortic valve pathology required for proper testing of these devices. To solve this limitation, for the first time, we developed a novel polymeric valve whose leaflets possess calcium hydroxyapatite inclusions immersed in them. This study reports the characteristics and feasibility of these valves. Two types of the polymeric valve, i.e., moderate and severe calcified AS models were developed and tested by deploying a transcatheter valve in those and measuring the related hemodynamics. The valves were tested in a heart flow simulator, and were studied using echocardiography. Our results showed high echogenicity of the polymeric valve, that was correlated to the severity of the calcification. Aortic valve area of the polymeric valves was measured, and the severity of stenosis was defined according to the clinical guidelines. Accordingly, we showed that these novel polymeric valves closely mimic AS, and can be a desired cost-saving solution for testing the performance of the transcatheter aortic valve systems in vitro.     

Raloxifene attenuates Gas6 and apoptosis in experimental aortic valve disease in renal failure

Renal failure is associated with aortic valve calcification. Using our rat model of uremia-induced reversible aortic valve calcification, we assessed the role of apoptosis and survival pathways in that disease. We also explored the effects of raloxifene, an estrogen receptor modulator, on valvular calcification. Gene array analysis was performed in aortic valves obtained from three groups of rats (n = 7 rats/group): calcified valves obtained from rats fed with uremic diet, valves after calcification resolution following diet cessation, and control. In addition, four groups of rats (n = 10 rats/group) were used to evaluate the effect of raloxifene in aortic valve calcification: three groups as mentioned above and a fourth group fed with the uremic diet that also received daily raloxifene. Evaluation included imaging, histology, and antigen expression analysis. Gene array results showed that the majority of the altered expressed genes were in diet group valves. Most apoptosis-related genes were changed in a proapoptotic direction in calcified valves. Apoptosis and decreases in several survival pathways were confirmed in calcified valves. Resolution of aortic valve calcification was accompanied by decreased apoptosis and upregulation of survival pathways. Imaging and histology demonstrated that raloxifene significantly decreased aortic valve calcification. In conclusion, downregulation of several survival pathways and apoptosis are involved in the pathogenesis of aortic valve calcification. The beneficial effect of raloxifene in valve calcification is related to apoptosis modulation. This novel observation is important for developing remedies for aortic valve calcification in patients with renal failure.     

Osteopontin controls endothelial cell migration in vitro and in excised human valvular tissue from patients with calcific aortic stenosis and controls

Calcific aortic stenosis (CAS) is a pathological condition of the aortic valve characterized by dystrophic calcification of the valve leaflets. Despite the high prevalence and mortality associated with CAS, little is known about its pathogenetic mechanisms. Characterized by progressive dystrophic calcification of the valve leaflets, the early stages of aortic valve degeneration are similar to the active inflammatory process of atherosclerosis including endothelial disruption, inflammatory cell infiltration, lipid deposition, neo-vascularization and calcification. In the vascular system, the endothelium is an important regulator of physiological and pathological conditions; however, the contribution of endothelial dysfunction to valvular degeneration at the cellular and molecular level has received little attention. Endothelial cell (EC) activation and neo-vascularization of the cusps characterizes all stages of aortic valvular degeneration from aortic sclerosis to aortic stenosis. Here we reported the role of osteopontin (OPN) in the regulation of EC activation in vitro and in excised tissue from CAS patients and controls. OPN is an important pro-angiogenic factor in several pathologies. High levels of OPN have been demonstrated in both tissue and plasma of patients with aortic valve sclerosis and stenosis. The characterization of valvular ECs as a cellular target for OPN will help us uncover the pathogenesis of aortic valve degeneration and stenosis, opening new perspectives for the prevention and therapy of this prevalent disease.     

An in vitro model quantifying the effect of calcification on the tissue–stent interaction in a stenosed aortic root

Transcatheter Aortic Valves rely on the tissue-stent interaction to ensure that the valve is secured within the aortic root. Aortic stenosis presents with heavily calcified leaflets and it has been proposed that this calcification also acts to secure the valve, but this has never been quantified. In this study, we developed an in vitro calcified aortic root model to quantify the role of calcification on the tissue-stent interaction. The in vitro model incorporated artificial calcifications affixed to the leaflets of porcine aortic heart valves. A self-expanding nitinol braided stent was deployed into non-calcified and artificially calcified porcine aortic roots and imaged by micro computed tomography. Mechanical tests were then conducted to dislodge the stent from the aortic root and it was found that, in the presence of calcification, there was a significant increase in pullout force (8.59 ± 3.68 N vs. 2.84 ± 1.55 N p = 0.045), stent eccentricity (0.05 ± 0.01 vs. 0.02 ± 0.01, p = 0.049), and coefficient of friction between the stent and aortic root (0.36 ± 0.12 vs. 0.09 ± 0.05, p = 0.018), when compared to non-calcified roots. This study quantifies for the first time the impact of calcification on the friction between the aortic tissue and transcatheter aortic valve stent, showing the role of calcification in anchoring the valve stent in the aortic root.     

Circulating activated and effector memory T cells are associated with calcification and clonal expansions in bicuspid and tricuspid valves of calcific aortic stenosis

We sought to delineate further the immunological significance of T lymphocytes infiltrating the valve leaflets in calcific aortic stenosis (CAS) and determine whether there were associated alterations in circulating T cells. Using clonotypic TCR β-chain length and sequence analysis we confirmed that the repertoire of tricuspid CAS valves contains numerous expanded T cell clones with varying degrees of additional polyclonality, which was greatest in cases with severe calcification. We now report a similar proportion of clonal expansions in the much younger bicuspid valve CAS cases. Peripheral blood flow cytometry revealed elevations in HLA-DR(+) activated CD8 cells and in the CD8(+)CD28(null)CD57(+) memory-effector subset that were significantly greater in both bicuspid and tricuspid CAS cases with more severe valve calcification. Lesser increases of CD4(+)CD28(null) T cells were identified, principally in cases with concurrent atherosclerotic disease. Upon immunostaining the CD8 T cells in all valves were mainly CD28(null), and CD8 T cell percentages were greatest in valves with oligoclonal repertoires. T cell clones identified by their clonotypic sequence as expanded in the valve were also found expanded in the circulating blood CD28(null)CD8(+) T cells and to a lesser degree in the CD8(+)CD28(+) subset, directly supporting the relationship between immunologic events in the blood and the valve. The results suggest that an ongoing systemic adaptive immune response is occurring in cases with bicuspid and tricuspid CAS, involving circulating CD8 T cell activation, clonal expansion, and differentiation to a memory-effector phenotype, with trafficking of T cells in expanded clones between blood and the valve.     

Bicuspid stenotic aortic valves: clinical characteristics and morphological assessment using MRI and echocardiography

Background

Bicuspid aortic valve (BAV) is one of the most common congenital heart defects with a population prevalence of 0.5% to 1.3%. Identifying patients with BAV is clinically relevant because BAV is associated with aortic stenosis, endocarditis and ascending aorta pathology.

Methods and Results

Patients with severe aortic stenosis necessitating aortic valve replacement surgery were included in this study. All dissected aortic valves were stored in the biobank of the University Medical Centre Utrecht. Additionally to the morphological assessment of the aortic valve by the surgeon and pathologist, echocardiographic and magnetic resonance imaging (MRI) images were evaluated. A total of 80 patients were included of whom 32 (40%) were diagnosed with BAV by the surgeon (gold standard). Patients with BAV were significantly younger (55 vs 71 years) and were more frequently male. Notably, a significant difference was found between the surgeon and pathologist in determining valve morphology. MRI was performed in 33% of patients. MRI could assess valve morphology in 96% vs 73% with echocardiography. The sensitivity of MRI for BAV in a population of patients with severe aortic stenosis was higher than echocardiography (75% vs 55%), whereas specificity was better with the latter (91% vs 79%). Typically, the ascending aorta was larger in patients with BAV.

Conclusion

Among unselected patients with severe aortic valve stenosis, a high percentage of patients with BAV were found. Imaging and assessment of the aortic valve morphology when stenotic is challenging.     

Ultrasonic Decalcification of Calcified Cardiac Valves and Annuli

Heavily calcified annuli increase the incidence of complications after prosthetic valve replacement—heart block, separation of the aorta or the atrium from the ventricle, late aneurysm formation, paravalvular leak, and haemolysis. An ultrasonic calculus-disintegrator has been developed to remove calcific deposits. The instrument is portable, robust, easily sterilized, inexpensive, and provides nebulized water at the ultrasonic tip which keeps the tissues cool, helps to break up the calculus by cavitation, and washes the calcific debris into the sucker. Preliminary trial on excised calcific valves showed the ultrasound instrument to be capable of removing most forms of calcification. In clinical prosthetic replacement of valves it enabled good clearance of the annulus to be performed in six out of seven cases, in one of which earlier operation had been unsuccessful because of calcification. Two elderly patients with pure calcific aortic stenosis were successfully treated by debridement of the aortic valve with ultrasound.     

Deficient signaling via Alk2 (Acvr1) leads to bicuspid aortic valve development

Bicuspid aortic valve (BAV) is the most common congenital cardiac anomaly in humans. Despite recent advances, the molecular basis of BAV development is poorly understood. Previously it has been shown that mutations in the Notch1 gene lead to BAV and valve calcification both in human and mice, and mice deficient in Gata5 or its downstream target Nos3 have been shown to display BAVs. Here we show that tissue-specific deletion of the gene encoding Activin Receptor Type I (Alk2 or Acvr1) in the cushion mesenchyme results in formation of aortic valve defects including BAV. These defects are largely due to a failure of normal development of the embryonic aortic valve leaflet precursor cushions in the outflow tract resulting in either a fused right- and non-coronary leaflet, or the presence of only a very small, rudimentary non-coronary leaflet. The surviving adult mutant mice display aortic stenosis with high frequency and occasional aortic valve insufficiency. The thickened aortic valve leaflets in such animals do not show changes in Bmp signaling activity, while Map kinase pathways are activated. Although dysfunction correlated with some pro-osteogenic differences in gene expression, neither calcification nor inflammation were detected in aortic valves of Alk2 mutants with stenosis. We conclude that signaling via Alk2 is required for appropriate aortic valve development in utero, and that defects in this process lead to indirect secondary complications later in life.     

Aortic valve stenosis: persistence of infective agents or noninfective inflammatory process?]

The probable risk factors leading to aortic valve calcification are not clearly defined. The cross-sectional study of 85 patients with vascular and valvular calcification was performed. Correlations between the immune tests and aortic stenosis severity were investigated. The predictors of aortic valve calcification were probably C-reactive protein and interleukin-6. The predictors of aortic stenosis progression were interleukin-8, antibodies of Chlamydia pneumoniae and cytomegalovirus, and dysregulation of complement's components. Implication of immune reactivity could influence aortic valve calcification.     

A correlation between long-term in vitro dynamic calcification and abnormal flow patterns past bioprosthetic heart valves

In this paper, a long-term in vitro dynamic calcification of three porcine aortic heart valves was investigated using a combined approach that involved accelerated wear testing of the valves in the rapid calcification solution, hydrodynamic assessment of the progressive change of effective orifice area (EOA) along with the transaortic pressure gradient, and quantitative visualization of the flow. The motivation for this study was developing a standardized, economical, and feasible in vitro testing methodology for bioprosthetic heart valve calcification, which would address both the hydrodynamic performance of the valves as well as the subsequent changes in the flow field. The results revealed the failure of the test valves at 40 million cycles mark, associated with the critical decrease in the EOA, followed by the increase in the maximum value of viscous shear stress of up to 52%, compared to the values measured at the beginning of the study. The decrease in the EOA was subsequently followed by the rapid increase in the maximum streamwise velocity of the central orifice jet up to the value of about 2.8 m/s, compared to the initial value of 2 m/s, and to the value of 2.2 m/s in the case of a control valve along with progressive narrowing of the velocity profile for two test valves. The significance of the current work is in demonstrating a correlation between calcification of the aortic valve and spatial as well as the temporal development of abnormal flow features.