Aortic Valve Hemodynamics Research Articles

Fluid-structure interaction simulation of the three-leaflet aortic valve using COMSOL

The simulation of the aortic valve (AV) remains challenging due to its geometric complexity and the multi-physics nature of the problem. In this study, we utilized COMSOL to establish a three-dimensional, three-leaflet AV fluid-structure interaction model and investigated the influence of material properties on the valve's mechanical behavior in a healthy state. The results indicated that variations in the aortic wall material model had a minor impact on AV hemodynamics. Additionally, while the linear elastic properties of the leaflets limit valve opening and closing, this material model allows for rapid assessment of AV performance within the range of material deformation.

Early outcomes with a fully retrievable SinoCrown transcatheter heart valve in patients with severe aortic stenosis.

This study summarizes and analyzes data from patients suffering from symptomatic aortic stenosis who successfully underwent transcatheter aortic valve implantation (TAVI) using a novel, completely retrievable transcatheter heart valve. We included patients who underwent a TAVI procedure with SinoCrown valves at our center between December 2021 and September 2022. We collected 1-year follow-up data on survival, complications, echocardiographic results, New York Heart Association functional class in heart failure, and patient-reported health-related quality of life outcomes. Eight successive patients (73.3 ± 4.3 years) were included in the study, with a median Society of Thoracic Surgery risk score of 4.26%. The procedure had a 100% success rate. Median postoperative discharge time was 7 days, with no 30-day hospital readmissions. Postoperative aortic valve hemodynamics improved, indicated by decreased transvalvular flow velocity compared with preoperative values (1.9 ± 0.2 vs. 4.9 ± 0.2 m/s, p < 0.0001). The median and maximum follow-up times were 8 and 12 months, respectively. During the follow-up period, there were no serious complications such as death, stroke, valve embolization, or high-grade atrioventricular block. The results from eight initial TAVI cases performed with the SinoCrown valve demonstrated promising safety and efficacy.

Nature of aortic annulus: Influence of annulus dynamic on the aortic valve hemodynamics

Accurate imaging reports of the aortic valve indicate that the diameter of the aortic annulus changes regularly during a cardiac cycle. Most of these studies aim to demonstrate the proper method for estimating the aortic annulus diameter before performing TAVR surgery, revealing that the aortic annulus is dynamic and not constant throughout the cardiac cycle. This raises the question of how fixing the aortic annulus might affect valve function, which is a question that still needs to be addressed. Therefore, the present study seeks to address this question and elucidate the dynamic impact of the aortic annulus on aortic valve hemodynamics.Two computational models based on this hypothesis were created and solved, and then their results were compared. Both models are identical, except for the intrinsic dynamic nature of the aortic annulus. One model consists of the dynamic behavior, and the other simulates a fixed annulus, resembling the effect of a TAVR operation, SAVR, or any phenomenon that eliminates the dynamic nature of the annulus.Our research findings indicate that the dynamic nature of the annulus enhances blood flow (+2.7 %), increases mean velocity (+11.9) and kinetic energy density (+34 %), prolongs momentum retention during systole, stabilizes the flow jet at the end of systole, reduces the required pressure to keep the leaflets open (−40.9 % at 0.3s), and sustains ventricular pressure superiority (+9.4 %) over the aorta for a longer duration (+17.7 % of systole), a crucial factor in preventing backflow during aortic valve closure. Based on these results, more attention should be paid to the dynamic nature of the annulus.

Non-Invasive Ultrasound Therapy for Severe Aortic Stenosis: Early Effects on the Valve, Ventricle, and Cardiac Biomarkers (A Case Series).

Background: Transcatheter aortic valve replacement (TAVR) was developed for inoperable patients with severe aortic stenosis. However, despite TAVR advancements, some patients remain untreated due to complex comorbidities, necessitating less-invasive approaches. Non-invasive ultrasound therapy (NIUT), a new treatment modality, has the potential to address this treatment gap, delivering short ultrasound pulses that create cavitation bubble clouds, aimed at softening embedded calcification in stiffened valve tissue. Methods: In the prospective Valvosoft® Serbian first-in-human study, we assessed the safety and efficacy of NIUT and its impact on aortic valve hemodynamics, on the left ventricle, and on systemic inflammation in patients with severe symptomatic aortic stenosis not eligible for TAVR or surgery. Results: Ten patients were included. Significant improvements were observed in hemodynamic parameters from baseline to one month, including a 39% increase in the aortic valve area (from 0.5 cm2 to 0.7 cm2, p = 0.001) and a 23% decrease in the mean transvalvular gradient (from 54 mmHg to 38 mmHg, p = 0.01). Additionally, left ventricular global longitudinal strain significantly rose, while global wasted work significantly declined at one month. A dose-response relationship was observed between treatment parameters (peak acoustic power, intensity spatial-peak pulse-average, and mean acoustic energy) and hemodynamic outcomes. NIUT was safely applied, with no clinically relevant changes in high-sensitivity troponin T or C-reactive protein and with a numerical, but not statistically significant, reduction in brain natriuretic peptide (from 471 pg/mL at baseline to 251 pg/mL at one month). Conclusions: This first-in-human study demonstrates that NIUT is safe and confers statistically significant hemodynamic benefits both on the valve and ventricle.

Patient-specific bicuspid aortic valve hemodynamics study based on computer simulation and in vitro experiment

Patient-specific bicuspid aortic valve hemodynamics study based on computer simulation and in vitro experiment

Patient-specific analysis of bicuspid aortic valve hemodynamics using a fully coupled fluid-structure interaction model

Bicuspid aortic valve (BAV), the most common congenital heart disease, is prone to develop significant valvular dysfunction and aortic wall abnormalities such as ascending aortic aneurysm. Growing evidence has suggested that abnormal BAV hemodynamics could contribute to disease progression. In order to investigate BAV hemodynamics, we performed 3D patient-specific fluid-structure interaction (FSI) simulations with fully coupled blood flow dynamics and valve motion throughout the cardiac cycle. Results showed that the hemodynamics during systole can be characterized by a systolic jet and two counter-rotating recirculation vortices. At peak systole, the jet was usually eccentric, with asymmetric recirculation vortices and helical flow motion in the ascending aorta. The flow structure at peak systole was quantified using the vorticity, flow rate reversal ratio and local normalized helicity (LNH) at four locations from the aortic root to the ascending aorta. The systolic jet was evaluated with the peak velocity, normalized flow displacement, and jet angle. It was found that peak velocity and normalized flow displacement (rather than jet angle) gave a strong correlation with the vorticity and LNH in the ascending aorta, which suggests that these two metrics could be used for clinical noninvasive evaluation of abnormal blood flow patterns in BAV patients.

Surgical aortic valve replacement etiologies, hemodynamics, and outcomes in 1346 patients from the Malaysian heart centre

BackgroundThis study examined the characteristics and outcomes of surgical aortic valve replacement (SAVR) both isolated and in combination with other cardiac surgery in Malaysia from 2015 to 2021.MethodsThis was a retrospective study of 1346 patients analyzed on the basis of medical records, echocardiograms and surgical reports. The overall sample was both considered as a whole and divided into aortic stenosis (AS)/aortic regurgitation (AR)-predominant and similar-severity subgroups.ResultsThe most common diagnosis was severe AS (34.6%), with the 3 most common etiologies being bicuspid valve degeneration (45.3%), trileaflet valve degeneration (36.3%) and rheumatic valve disease (12.2%). The second most common diagnosis was severe AR (25.5%), with the most common etiologies being root dilatation (21.0%), infective endocarditis (IE) (16.6%) and fused prolapse (12.2%). Rheumatic valve disease was the most common mixed disease. A total of 54.5% had AS-predominant pathology (3 most common etiologies: bicuspid valve degeneration valve, degenerative trileaflet valve and rheumatic valve disease), 36.9% had AR-predominant pathology (top etiologies: root dilatation, rheumatic valve disease and IE), and 8.6% had similar severity of AS and AR. Overall, 62.9% of patients had trileaflet valve morphology, 33.3% bicuspid, 0.6% unicuspid and 0.3% quadricuspid. For AS, the majority were high-gradient severe AS (49.9%), followed by normal-flow low-gradient (LG) severe AS (10.0%), paradoxical low-flow (LF)-LG severe AS (6.4%) and classical LF-LG severe AS (6.1%). The overall in-hospital and total 1-year mortality rates were 6.4% and 14.8%, respectively. Pure severe AS had the highest mortality. For AS-predominant pathology, the etiology with the highest mortality was trileaflet valve degeneration; for AR-predominant pathology, it was dissection. The overall survival probability at 5 years was 79.5% in all patients, 75.7% in the AS-predominant subgroup, 83.3% in the AR-predominant subgroup, and 87.3% in the similar-severity subgroup.ConclusionsThe 3 most common causes of AS- predominant patients undergoing SAVR is bicuspid valve degeneration, degenerative trileaflet valve and rheumatic and for AR-predominant is root dilatation, rheumatic and IE. Rheumatic valve disease is an important etiology in our SAVR patients especially in mixed aortic valve disease.Study registration IJNREC/562/2022.

Echocardiographic parameters associated with less reverse left ventricular remodeling after transcatheter aortic valve implant in subjects with prosthesis patient mismatch.

Transaortic valve implant (TAVI) is the treatment of choice for severe aortic stenosis (AS). Some patients develop prosthesis patient mismatch (PPM) after TAVI. It is challenging to determine which patients are at risk for clinical deterioration. We retrospectively measured echocardiographic parameters of left ventricular (LV) morphology and function, prosthetic aortic valve effective orifice area (iEOA) and hemodynamics in 313 patients before and 1year after TAVI. Our objective was to compare the change in echocardiographic parameters associated with left ventricular reverse modeling in subjects with and without PPM. Our secondary objective was to evaluate echo parameters associated with PPM and the relationship to patient functional status and survival post-TAVI. We found that 82 (26.2%) of subjects had moderate and 37 (11.8%) had severe PPM post-TAVI. There was less relative improvement in LVEF with PPM (1.9±21.3% vs. 8.2+30.1%, p=.045). LV GLS also exhibited less relative improvement in those with PPM (13.4+34.1% vs. 30.9+73.3%, p=.012). NYHA functional class improved in 84.3% of subjects by one grade or more. Echocardiographic markers of PPM were worse in those without improvement in NYHA class (mean AT/ET was .29 vs. .27, p=.05; DVI was .46 vs. .51, p=.021; and iEOA was .8cm/m2 vs. .9cm/m2 , p=.025). There was no association with PPM and survival. There was no improvement in LVEF and less improvement in LV GLS in those with PPM post-TAVI. Echocardiographic markers of PPM were present in those with lack of improvement in NYHA functional class.

Impact of pre-procedural bioprosthetic leaflet calcification on hemodynamic and hlinical outcomes after aortic valve-in-valve procedure

Abstract Background Transcatheter aortic valve replacement (TAVR) is a recognized option to treat patients with aortic bioprosthetic failure, but preprocedural factors associated with poor hemodynamic and clinical outcomes after valve-in-valve (ViV) TAVR remain unclear. In TAVR performed in native aortic valve, higher degrees of aortic valve calcification (AVC) have been associated with poorer outcome, but the association of bioprosthetic AVC and outcomes after ViV TAVR remains unknown. We hypothesize that a high amount of pre-procedural bioprosthetic AVC may result in a higher risk of patient-prosthesis mismatch (PPM) or post-procedural intervalvular regurgitation, and increased mid-term mortality. Purpose To assess the association of pre-procedural surgical bioprosthetic AVC and short- and mid-term hemodynamic and clinical outcomes after aortic ViV procedure. Methods All consecutive patients who underwent aortic ViV procedure for surgical aortic bioprosthetic failure at our institution between 2009-2022 with available pre-procedural CT were included, patients with TAVR-in-TAVR were excluded. We measured AVC with non-contrast CT, and this amount was divided by LVOT area (measured on echocardiography) to obtain AVC density (AVCD). Pre and post-procedural transthoracic echocardiograms were analyzed for aortic valve hemodynamics. Multivariate Cox-regression was performed to assess the determinants of mid-term all-cause mortality. Results A total of 186 patients were included. An AVCD score above the median was associated with younger age, diabetes, lower indexed aortic valve area and higher preprocedural mean gradient (figure 1). Preprocedural AVCD was not significantly different in patients with: 1) postprocedural severe PPM (n=81, 45%) vs no-moderate PPM (n=100, 55%) (207 [68-335] vs 209 [54-352] Agatston units (AU)/cm2, p=0.80); 2) ≥moderate intervalvular regurgitation (n=10, 5%) vs no-mild regurgitation (n=174, 90%) (198 [57-350] vs 251 [210-352] AU/cm2, p=0.22). Higher AVCD was not associated with 30-day mortality, stroke, or implantation of a new pacemaker (all p&amp;gt;0.05). During 38 [21-65] months of follow-up, multivariate factors associated with all-cause mortality were older age, diabetes, and chronic obstructive pulmonary disease, while AVCD was associated with a lower mortality (HR 0.77 (0.63-0.94) per 100 AU/cm2 increase, p=0.01). Conclusion High pre-procedural bioprosthetic ACVD is not associated with a poorer hemodynamic and clinical after Aortic ViV procedure for surgical bioprosthetic failure.Baseline tableSurvival curve

Risk factors and clinical effects of subclinical leaflet thrombosis after transcatheter aortic valve replacement.

The number of trans-catheter aortic valve replacement (TAVR) procedure is increasing; However, the incidence of leaflet thrombosis is higher in TAVR than in surgical aortic valve replacement (SAVR). In this study, the risk factors for leaflet thrombosis after TAVR and its effects on hemodynamics and clinical course were investigated. Multidetector computed tomography (MDCT) was performed at 1year after TAVR in 94 patients from January 2015 to October 2020 at Samsung Medical Center in South Korea. Among the 94 patients, subclinical leaflet thrombosis occurred in 20 patients, and risk factors were analyzed. In addition, the difference in aortic valve (AV) hemodynamics between the two groups was examined and clinical outcomes compared. Indexed mean sinus of Valsalva (SOV) diameter, AV calcium volume, and post-procedure effective orifice area (EOA) were predictive of subclinical leaflet thrombosis with the area under the curve (AUC) value of 0.670 (P-value = 0.020), 0.695 (P-value = 0.013), and 0.665 (P-value = 0.031), respectively. In echocardiography performed at the time of follow-up CT, the value of AV max velocity and AV mean pressure gradient were higher in the thrombosis group and the EOA and Doppler velocity index values were lower in the thrombosis group than in the no thrombosis group. Clinical outcome was not significantly different between the two groups (log-rank P-value = 0.26). Larger indexed SOV diameter, higher AV calcium volume, and smaller post-procedure AV EOA were risk factors for subclinical leaflet thrombosis after TAVR. Subclinical leaflet thrombosis has a benign course when properly managed.

Sex Differences in LV Remodeling and Hemodynamics in Aortic Stenosis: Sex-Specific Criteria for Severe Stenosis?

BackgroundThe current criteria for aortic stenosis (AS) severity have not incorporated sex-related differences. ObjectivesThe authors investigated sex-related serial changes in left ventricular (LV) structure/function and hemodynamics in AS. MethodsSerial echocardiograms of patients with severe AS (time 0; aortic valve area [AVA] ≤1 cm2) and ≥1 previous echocardiogram were compared between sexes. ResultsOf 927 patients (time 0: AVA 0.87 ± 0.11 cm2, peak velocity 4.03 ± 0.65 m/s, mean Doppler systolic pressure gradient [MG] 40.6 ± 13.1 mm Hg), 393 (42%) were women. Women had smaller body surface area (BSA) (1.77 ± 0.22 m2 vs 2.03 ± 0.20 m2; P < 0.001), lower stroke volume (SV) (81.1 ± 17.2 mL vs 88.3 ± 18.6 mL; P < 0.001), and more frequent low-gradient severe AS (n = 196 [50%] vs n = 181 [34%]; P < 0.001). Women consistently had smaller AVA, indexed AVA (AVAi), peak velocity, and MG than men. The difference in aortic valve gradient lessened when AVAi ≤0.6 cm2/m2 was applied as severe AS (n = 694, women 43%, AVA 0.95 ± 0.17 cm2, AVAi 0.50 ± 0.07 cm2/m2). Peak velocity (3.83 ± 0.66 m/s) and MG (36.5 ± 13.2 mm Hg) were lower based on AVAi severity criteria compared to those based on AVA. Men had a lower left ventricular ejection fraction (LVEF) (55.8% ± 14.8% vs 61.1% ± 11.7%; P < 0.001) and greater reduction in SV (−13.3 ± 19.6 mL vs −7.4 ± 16.4 mL; P < 0.001) as AS progressed from moderate to severe. Concentric LV hypertrophy was more common and E/eʹ higher in women (21.2 ± 10.9 vs 18.8 ± 9.1; P < 0.001). SV, LVEF, AVA, peak velocity, and MG became precipitously worse when AVA reached 1.2 cm2 in both sexes. ConclusionsSmaller BSA in women yields lower SV, resulting in lower aortic valve gradient than men. Indexed parameters by BSA are thus important in sex-related differences of aortic valve hemodynamics, but AVAi ≤0.6 cm2/m2 includes individuals with moderate AS. Elevated filling pressure is more common in women. Men experience a larger reduction in SV and LVEF as AS progresses. The definition of AS severity may require different criteria between sexes.

Bicuspid aortic valve morphology and hemodynamics by same-day echocardiography and cardiac MRI.

This study investigated the impact of bicuspid aortic valve (BAV) on valve morphology and motion as well as proximal and aortic hemodynamics using a same-day echocardiography and cardiac MRI. Transthoracic echocardiography, two-dimensional cine MRI of the aortic valve, and aortic 4D flow MRI were performed on the same day in 9 normofunctional BAV patients (age = 41 ± 12, 3 female), 4 BAV with moderate to severe aortic stenosis (AS) (age = 63 ± 5, 1 female), and 36 healthy tricuspid aortic valve controls (age = 52 ± 10, 21 female). Valve opening and closing timings and transvalvular peak velocity were measured using B-mode and Doppler echocardiogram, respectively. Valve orifice morphology at a fully-opened state was characterized using cine MRI. Ascending aortic (AAo) wall shear stress (WSS) was measured using 4D flow MRI data. Valve motion timings were similar between BAV and controls. BAV was associated with an increased orifice aspect ratio (1.44 ± 0.11 vs. 1.10 ± 0.13, P < 0.001), transvalvular peak velocity (1.5 ± 0.3 vs. 1.2 ± 0.2m/s, P < 0.001) and maximum AAo WSS (1.62 ± 0.31 vs. 0.91 ± 0.24Pa, P < 0.001). The increased orifice aspect ratio was associated with the increase in transvalvular peak velocity (r = 0.80, P < 0.0001) and maximum AAo WSS (r = 0.83, P < 0.0001). Transvalvular peak velocity was also positively correlated with maximum AAo WSS (r = 0.83, P < 0.0001). A same-day echo and MRI imaging allows for a comprehensive assessment of the impact of aortic valve disease on valve function and hemodynamics. In this pilot application to BAV, we found increased orifice aspect ratio may be responsible for increased transvalvular peak velocity and maximum AAo WSS.

Propensity-matched comparison of balloon-expandable and self-expanding valves for transcatheter aortic valve replacement in a Chinese population.

BackgroundBalloon-expandable valves (BEV) and self-expanding valves (SEV) for transcatheter aortic valve replacement (TAVR) have shown promising results in Western populations. Herein, we comparatively evaluated their hemodynamics and early clinical outcomes in a Chinese population.MethodsOne hundred seventy-eight patients with symptomatic aortic stenosis who had undergone transfemoral TAVR using SEV (n=153; Venus-A, 97; VitaFlow, 56) or BEV (n=25; Sapien3) from September 2020 to April 2021 were retrospectively enrolled, and 25 pairs were propensity-score matched for 10 baseline variables. The primary study outcomes were aortic valve hemodynamics and postoperative complications at discharge and 3-month follow-up.ResultsTAVR was successful in all patients. Compared with SEV group, the BEV group had similarly distributed baseline characteristics, procedural time, hospital stay, new pacemaker implantation, and paravalvular regurgitation grade. We also observed that the BEV group had lower rates of balloon pre-dilation (60% vs. 92%, P=0.018), post-dilation (0 vs. 20%, P=0.050) and second valve implantation (0 vs. 24%, P=0.022); higher mean transaortic gradient (14.3±6.1 vs. 10.8±4.9, P=0.030) and proportion of patients with elevated gradients (20% vs. 0, P=0.050) at discharge; and similar rehospitalization, mean transaortic gradient, new pacemaker implantation, and paravalvular regurgitation grade than the SEV group at the 3-month follow-up. There were no deaths in either group. However, the proportion of patients with elevated gradients in SEV group was higher at 3 months than before discharge (24% vs. 0, P=0.022).ConclusionsBEV and SEV for transfemoral TAVR appear comparably safe and effective, with high device success and favorable 3-month clinical outcomes. However, the transaortic gradient and new pacemaker implantation in the SEV group increased during follow-up, warranting larger studies with longer-term follow-up.

An AI Based Detection System of “At Risk” Aortic Stenosis

Aortic Stenosis (AS) causes abnormal aortic valve haemodynamics and changes in cardiac structure (“AS Phenotype”), is associated with high mortality, and has prompted calls for echocardiography report automation. We explored whether Artificial Intelligence (AI) could meet this need by automatically detecting the AS phenotype.

Changes in aortic valve hemodynamics and ventricular functional measurements in patients undergoing transcatheter and surgical aortic valve replacement: a head-to-head comparison

Abstract Introduction Both surgical and transcatheter aortic valve replacement are effective interventions for treatment of patients with severe aortic stenosis. Data from landmark randomized trials have shown comparable improvement in aortic valve hemodynamics and left ventricular remodeling. Whether similar patterns will be observed in real-world practice has not been completely investigated. Purpose To compare the impact of transcatheter aortic valve replacement (TAVR) and surgical aortic valve replacement (SAVR) on short- and intermediate-term changes in aortic valve hemodynamics and left ventricular reverse-remodeling. Methods A total of 213 patients with severe AS were referred for TAVR (n=137) or SAVR (n=76) at a single center (August/ 2015-Feb/ 2021). Patient demographics and echocardiographic parameters of aortic valve stenosis severity were collected retrospectively. Changes over-time in aortic valve area, mean gradient, dimensionless index, left ventricular ejection fraction (EF), and ventricular septal thickness were examined using linear mixed models. Results Patients undergoing TAVR were older with higher STS risk scores and a greater burden of comorbidities (Table). Over a median follow-up of 13 months (IQR 4–31), both groups experienced a significant reduction in aortic valve mean gradient (25.7 mmHg with TAVR and 18.8 mmHg with SAVR), with no significant between-group difference (P=0.15). Aortic valve dimensionless index significantly increased in TAVR and SAVR groups (0.23 and 0.13, respectively) and was more pronounced in the TAVR group (P=0.01). Similarly, aortic valve area increased significantly in both groups (0.66 cm2 and 0.42 cm2, respectively) without a significant across-group difference (P=0.07). On the other hand, left ventricular ejection fraction did not change significantly over time (−0.61 and 1.15 EF points, respectively) with no significant between-group difference at 12 months (P=0.06). Ventricular septal thickness was significantly reduced in both groups, with no significant between group difference (P=0.4; Figure). Conclusion In this real-world experience, both TAVR and SAVR were associated with significant improvement in aortic valve hemodynamic parameters and modest reverse left ventricular remodeling. Furthermore, these changes were comparable with both modalities, adding to available evidence from randomized clinical trials on beneficial effects of both TAVR and SAVR. Funding Acknowledgement Type of funding sources: None. Table 1Figure 1

Comparison of transvalvular flow rate in aortic stenosis subtypes.

Evaluate ET and TVFR in normal patients, PLFLGAS, LGLFAS, and classic pre and post TAVR. Severe aortic stenosis (AS) is defined echocardiographically. Generating a pressure gradient to meet diagnostic criteria is dependent on left ventricular contractility, stroke volume, and ejection time. Abnormalities in these decrease the mean pressure gradient across the valve creating pathology termed low flow, low gradient AS. This occurs in two subtypes, low ejection fraction LFLGAS and paradoxical LFLGAS (PLFLGAS), in which EF is normal but stroke volume is<35ml/m2 . Paradoxical LFLGAS is difficult to diagnose and does not have a confirmatory echocardiographic parameter. Transvalvular flow rate (TVFR), which is defined as stroke volume divided by the ejection time, provides a direct measure of flow across the aortic valve. A retrospective study of patients who underwent transcatheter aortic valve replacement (TAVR) at the University of Cincinnati Medical Center between 2016 and 2019 was performed. Patients were classified by AS subtype. ET and TVFR were measured pre and post TAVR and statistically compared using SPSS statistics software and ANOVA analysis. Pre TAVR TVFR in the normal population, severe AS population, and LFLGAS were not significantly different. The pre TAVR TVFR in paradoxical LFLGAS patients was significantly lower than other groups. TVFR improved to the greatest degree post TAVR in PLFLGAS but did not meet statistical significance. The significantly lower TVFR demonstrated in PLFLGAS provides a comprehensive, direct measurement of aortic valve hemodynamics and PLFLGAS pathology and can aid in diagnosis.

Computational Analysis of Wall Shear Stress Patterns on Calcified and Bicuspid Aortic Valves: Focus on Radial and Coaptation Patterns

Calcification and bicuspid valve formation are important aortic valve disorders that disturb the hemodynamics and the valve function. The detailed analysis of aortic valve hemodynamics would lead to a better understanding of the disease’s etiology. We computationally modeled the aortic valve using simplified three-dimensional geometry and inlet velocity conditions obtained via echocardiography. We examined various calcification severities and bicuspid valve formation. Fluid-structure interaction (FSI) analyses were adapted using ANSYS Workbench to incorporate both flow dynamics and leaflet deformation accurately. Simulation results were validated by comparing leaflet movements in B-mode echo recordings. Results indicate that the biomechanical environment is significantly changed for calcified and bicuspid valves. High flow jet velocities are observed in the calcified valves which results in high transvalvular pressure difference (TPG). Wall shear stresses (WSS) increased with the calcification on both fibrosa (aorta side) and ventricularis (left ventricle side) surfaces of the leaflet. The WSS distribution is regular on the ventricularis, as the WSS values proportionally increase from the base to the tip of the leaflet. However, WSS patterns are spatially complex on the fibrosa side. Low WSS levels and spatially complex WSS patterns on the fibrosa side are considered as promoting factors for further calcification and valvular diseases.

Usefulness of velocity ratio in patients with moderate aortic stenosis and reduced left ventricular ejection fraction

Background. Moderate aortic stenosis (AS) increases left ventricular afterload and results in unfavorable outcomes in patients with reduced left ventricular ejection fraction (LVEF). Velocity ratio (VR) may be appropriate for the evaluation of aortic valve (AV) hemodynamics because of the low dependence on flow. Therefore, this study investigated the usefulness of VR on the clinical outcomes of such patients. Method. Clinical data of patients with moderate AS (AV area, 0.60–0.85 cm2/m2; peak AV velocity, 2.0–4.0 m/s) and reduced LVEF (LVEF 20–50%) were analyzed during 2010–2018. VR was calculated as peak left ventricular outflow tract velocity/peak AV velocity. The primary endpoint included all-cause death, heart failure hospitalization, and AV replacement. Results. In total, 104 patients (mean age, 75.9 ± 7.0 years; 62.5% men) were included. LVEF was 39.5% ± 7.8%. The AV area was 0.72 ± 0.08 cm2/m2, peak AV velocity was 2.59 ± 0.40 m/s, and VR was 0.30 ± 0.07. The follow-up period was 1.7 (0.5–3.5) years. Kaplan–Meier estimates for the endpoint were 59.9% at 3 years. Multivariable analysis revealed that VR (hazard ratio, 0.947; 95% confidence interval, 0.905–0.990; p = .018) was significantly related to this endpoint. Patients with a VR <0.25 had significantly higher incidence rates of the endpoint than those with a VR ≥0.25 (85.6% versus 47.8% at 3 years; p < .001). Conclusions. Patients with moderate AS and reduced LVEF have unfavorable clinical outcomes, particularly those with low VR.

Parametric Computational Assessment of Valvular Dysfunction in Discrete Subaortic Stenosis and Aortoseptal Angle Abnormalities

Objective: Discrete subaortic stenosis (DSS) is a left-ventricular outflow tract (LVOT) obstruction caused by a membranous lesion. DSS is commonly associated with steep aortoseptal angles (AoSAs) and is a major risk factor for aortic regurgitation (AR). However, the etiology of AR secondary to DSS remains poorly understood. This study aimed at quantifying computationally the mechanistic impact of AoSA steepening and DSS on aortic valve (AV) hemodynamics and AR development. Methods: A 2D LV geometry reconstructed from cine-MRI data was connected to an AV geometry to generate a unified 2D LV-AV model (Figure 1A). Six geometrical variants were considered: unobstructed (CTRL) and DSS-obstructed LVOT (DSS), each reflecting three AoSA variations (110°, 120°, 130°). (Figure 1B). Fluid-structure interaction simulations were run to compute LV blood flow, AV leaflet dynamics, and regurgitant fraction (RF). Results: AoSA steepening and DSS generated vortex dynamics alterations and stenotic flow conditions (Figure 1D). While the CTRL-110° generated the highest degree of leaflet opening asymmetry, DSS preferentially altered superior leaflet kinematics, and caused leaflet-dependent alterations in systolic fluttering. LVOT steepening and DSS subjected the leaflets to increasing WSS overloads (up to 94% increase in temporal shear magnitude), while DSS also increased WSS bidirectionality on the inferior leaflet belly (+0.30-point in oscillatory shear index) (Figure 1E). Although AoSA steepening and DSS increased diastolic transvalvular backflow, regurgitant fractions (RF<7%) remained below the threshold defining clinical mild AR. Conclusions: The mechanical interactions between AV leaflets and LVOT steepening/DSS hemodynamic derangements do not cause AR. However, the leaflet WSS abnormalities predicted in those anatomies provide new support to a mechanobiological etiology of AR secondary to DSS. Figure 1. Unified 2D LV-AV FSI simulations in unobstructed (CTRL) and obstructed (DSS) LVOT anatomies: A) schematic showing the LV-AV assembly, B) LVOT geometries in considered in this study, C) AV geometry with WSS characterization sites, D) snapshots of velocity vector and vorticity contour fields taken at peak systole, E) 3D surface plots regional showing time-averaged WSS characteristics for all models

A computational study of the hemodynamics of bioprosthetic aortic valves with reduced leaflet motion

We employ a reduced degree-of-freedom aortic valve model to investigate the flow physics associated with early-stage reduced leaflet motion in bioprosthetic aortic valves. The model is coupled with a sharp-interface immersed boundary based incompressible flow solver to efficiently simulate the fluid–structure interaction. A total of 19 cases of flow through aortic valves with varying degrees of reduced leaflet motion (RLM) are considered. The characteristics of the aortic jet and the consequent aorta wall loading patterns are analyzed. Our results show that asymmetric RLM tilts the aortic jet and leads to large reverse and recirculating flow regions downstream from leaflets with restricted mobility. The changes in flow patterns increase wall pressure and shear stress fluctuations, and result in asymmetric oscillating shear on the aorta wall. These findings have implications for auscultation based diagnosis of this condition as well as the health of the aorta.