Understanding the role of the left atrial appendage on the flow in the atrium.

BACKGROUND: The exclusion/occlusion of the left atrial appendage (LAA) is a treatment option for atrial fibrillation (AF) patients who are at high risk of stroke and high risk of bleeding. As the role of the LAA is not well understood or explored, this study aims to assess its role on flow dynamics in the left atrium. METHODS: Computational fluid dynamics (CFD) simulations were carried out for nine AF patients before and after LAA exclusion. The flow parameters investigated included the LA velocities, Time Averaged Wall Shear Stress (TAWSS), Oscillatory Shear Index (OSI), Relative Residence Time (RRT), and Pressure in the LA. RESULTS: This study shows that, on average, a decrease in TAWSS (1.82 ± 1.85 Pa to 1.27 ± 0.96 Pa, p < 0.05) and a slight increase in OSI (0.16 ± 0.10 to 0.17 ± 0.10, p < 0.05), RRT (1.87 ± 1.84 Pa-1 to 2.11 ± 1.78 Pa-1, p < 0.05), and pressure (-19.2 ± 6.8 mmHg to -15.3 ± 8.3 mmHg, p < 0.05) were observed in the LA after the exclusion of the LAA, with a decrease in low-magnitude velocities. CONCLUSION: The exclusion of the LAA seems to be associated with changes in LA flow dynamics. Further studies are needed to elucidate the clinical implications of these changes.

Integrating Cardiovascular Engineering and Biofluid Mechanics in High School Science, Technology, Engineering, and Mathematics Education: An Experiential Approach.

Science, technology, engineering, and mathematics (STEM) education workshops and programs play a key role in promoting early exposure to scientific applications and questions. Such early engagement leads to growing not only passion and interest in science, but it also leads to skill development through hands-on learning and critical thinking activities. Integrating physiology and engineering together is necessary especially to promote health technology awareness and introduce the young generation to areas where innovation is needed and where there is no separation between health-related matters and engineering methods and applications. To achieve this, we created a workshop aimed at K-12 (grades 9-11) students as part of the Summer Youth Programs at Michigan Technological University. The aim of this workshop was to expose students to how engineering concepts and methods translate into health- and medicine-related applications and cases. The program consisted of a total of 15 h and was divided into three sections over a period of 2 weeks. It involved a combination of theoretical and hands-on guided activities that we developed. At the end of the workshop, the students were provided a lesson or activity-specific assessment sheet and a whole workshop-specific assessment sheet to complete. They rated the programs along a 1-5 Likert scale and provided comments and feedback on what can be improved in the future. Students rated hands-on activities the highest in comparison with case studies and individual independent research. Conclusively, this STEM summer-youth program was a successful experience with many opportunities that will contribute to the continued improvement of the workshop in the future.

Impact of blood pressure on coronary perfusion and valvular hemodynamics after aortic valve replacement.

OBJECTIVE: Our objective was to evaluate the impact of various blood pressures (BPs) on coronary perfusion and valvular hemodynamics following aortic valve replacement (AVR). BACKGROUND: Lower systolic and diastolic (SBP/DBP) pressures from the recommended optimal target range of SBP < 120-130 mmHg and DBP < 80 mmHg after AVR have been independently associated with increased cardiovascular and all-cause mortality. METHODS: The hemodynamic assessment of a 26 mm SAPIEN 3 transcatheter aortic valve (TAV), 29 mm Evolut R TAV, and 25 mm Magna Ease surgical aortic valve (SAV) was performed in a pulsed left heart simulator with varying SBP, DBP, and heart rate (HR) conditions (60 and 120 bpm) at 5 L/min cardiac output (CO). Average coronary flow (CF), effective orifice areas (EOAs), and valvulo-arterial impedance (Zva) were calculated. RESULTS: At HR of 60 bpm, at SBP < 120 mmHg and DBP < 60 mmHg, CF decreased below the physiological lower limit with several different valves. Zva and EOA were found to increase and decrease respectively with increasing SBP and DBP. The same results were found with an HR of 120 bpm. The trends of CF variation with BP were similar in all valves however the drop below the lower physiological CF limit was valve dependent. CONCLUSION: In a controlled in vitro system, with different aortic valve prostheses in place, CF decreased below the physiologic minimum when SBP and DBP were in the range targeted by blood pressure guidelines. Combined with recent observations from patients treated with AVR, these findings underscore the need for additional studies to identify the optimal BP in patients treated with AVR for AS.

Implications of hydrodynamic testing to guide sizing of self-expanding transcatheter heart valves for valve-in-valve procedures.

AIMS: The commonly used valve-in-valve (VIV) app recommends sizing based on dimensions of both the transcatheter heart valve (THV) and bioprosthetic surgical valve. The implications of hydrodynamic testing to guide VIV sizing are poorly understood. This bench study assessed the hydrodynamic performance of different sizes of self-expanding supra-annular THVs in three different surgical aortic bioprostheses at different implantation depths. METHODS: A small versus medium ACURATE neo (ACn), and a 26 mm versus 29 mm Evolut R were assessed after VIV implantation in 25 mm Mitroflow, Mosaic, and Magna Ease aortic surgical bioprostheses, at three implantation depths (+2 mm, -2 mm, and -6 mm). RESULTS: The medium-sized ACn had lower gradients compared to the small ACn when the THV was implanted high (+2 mm, or -2 mm). The 29 mm Evolut R had lower gradients compared to a 26 mm Evolut R for all implantation depths, except for a depth of -2 mm in the 25 mm Mitroflow. The medium ACn and 29 mm Evolut R had larger effective orifice areas compared to the small ACn and 26 mm Evolut R, respectively. Both Evolut R sizes had acceptable regurgitant fractions (<15%), while both ACn sizes were above the acceptable performance criteria (>15%), at all implantation depths. CONCLUSIONS: Use of a larger self-expanding THV was associated with superior hydrodynamic performance if the THV was implanted high. Hydrodynamic testing can provide additional information to the VIV app to help guide VIV sizing.

Effect of Blood Pressure Levels on Sinus Hemodynamics in Relation to Calcification After Bioprosthetic Aortic Valve Replacement.

Coexisting hypertension and aortic stenosis are common. Some studies showed that elevated blood pressures may be associated with progression of calcific aortic valve disease (CAVD) while others showed no correlation. Flow dynamics in the sinuses of Valsalva are considered key factors in the progression of CAVD. While the relationship between hemodynamics and CAVD is not yet fully understood, it has been demonstrated that they are tightly correlated. This study aims to investigate the effect of changing systolic and diastolic blood pressures (SBP and DBP, respectively) on sinus hemodynamics in relation to potential initiation or progression of CAVD after aortic valve replacement (AVR). Evolut R, SAPIEN 3 and Magna valves were deployed in an aortic root under pulsatile conditions. Using particle image velocimetry, the hemodynamics in the sinus were assessed. The velocity, vorticity, circulation ( Γ ) and shear stress were calculated. This study shows that under elevated SBP and DBP, velocity, vorticity, and shear stress nearby the leaflets increased. Additionally, larger fluctuations of Γ and area under the curve throughout the cardiac cycle were observed. Elevated blood pressures are associated with higher velocity, vorticity, and shear stress near the leaflets which may initiate or accelerate pro-calcific changes in the prosthetic leaflets leading to bioprosthetic valve degeneration.

Analysis of Energy and Pressure in the Sinus with Different Blood Pressures after Bioprosthetic Aortic Valve Replacement.

PURPOSE: To investigate the effect of changing systolic and diastolic blood pressures (SBP and DBP, respectively) on sinus flow and valvular and epicardial coronary flow dynamics after TAVR and SAVR. METHODS: SAPIEN 3 and Magna valves were deployed in an idealized aortic root model as part of a pulse duplicating left heart flow loop simulator. Different combinations of SBP and DBP were applied to the test setup and the resulting change in total coronary flow from baseline (120/60 mmHg), effective orifice area (EOA), and left ventricular (LV) workload, with each combination, was assessed. In addition, particle image velocimetry was used to assess the Laplacian of pressure ( ∇ 2 P ) in the sinus, coronary and main flow velocities, the energy dissipation rate (EDR) in the sinus and the LV workload. RESULTS: This study shows that under an elevated SBP, there is an increase in the total coronary flow, EOA, LV workload, peak velocities downstream of the valve, ∇ 2 P , and EDR. With an elevated DBP, there was an increase in the total coronary flow and ∇ 2 P . However, EOA and LV workload decreased with an increase in DBP, and EDR increased with a decrease in DBP. CONCLUSIONS: Blood pressure alters the hemodynamics in the sinus and downstream flow following aortic valve replacement, potentially influencing outcomes in some patients.

Differential Impact of Blood Pressure Control Targets on Epicardial Coronary Flow After Transcatheter Aortic Valve Replacement.

Background: The cause for the association between increased cardiovascular mortality rates and lower blood pressure (BP) after aortic valve replacement (AVR) is unclear. This study aims to assess how the epicardial coronary flow (ECF) after AVR varies as BP levels are changed in the presence of a right coronary lesion. Methods: The hemodynamics of a 3D printed aortic root model with a SAPIEN 3 26 deployed were evaluated in an in vitro left heart simulator under a range of varying systolic blood pressure (SBP) and diastolic blood pressure (DBP). ECF and the flow ratio index were calculated. Flow index value <0.8 was considered a threshold for ischemia. Results: As SBP decreased, the average ECF decreased below the physiological coronary minimum at 120 mmHg. As DBP decreased, the average ECF was still maintained above the physiological minimum. The flow ratio index was >0.9 for SBP ≥130 mmHg. However, at an SBP of 120 mmHg, the flow ratio was 0.63 (p ≤ 0.0055). With decreasing DBP, no BP condition yielded a flow ratio index that was less than 0.91. Conclusions: Reducing BP to the current recommended levels assigned for the general population after AVR in the presence of coronary artery disease may require reconsideration of levels and treatment priority. Additional studies are needed to fully understand the changes in ECF dynamics after AVR in the presence and absence of coronary artery disease.

Association of Bovine Arch Anatomy With Incident Stroke After Transcatheter Aortic Valve Replacement.

BACKGROUND: Acute ischemic stroke complicates 2% to 3% of transcatheter aortic valve replacements (TAVRs). This study aimed to identify the aortic anatomic correlates in patients after TAVR stroke. METHODS AND RESULTS: This is a single-center, retrospective study of patients who underwent TAVR at the Mayo Clinic between 2012 and 2022. The aortic arch morphology was determined via a manual review of the pre-TAVR computed tomography images. An "a priori" approach was used to select the covariates for the following: (1) the logistic regression model assessing the association between a bovine arch and periprocedural stroke (defined as stroke within 7 days after TAVR); and (2) the Cox proportional hazards regression model assessing the association between a bovine arch and long-term stroke after TAVR. A total of 2775 patients were included (59.6% men; 97.8% White race; mean±SD age, 79.3±8.4 years), of whom 495 (17.8%) had a bovine arch morphology. Fifty-seven patients (1.7%) experienced a periprocedural stroke. The incidence of acute stroke was significantly higher among patients with a bovine arch compared with those with a nonbovine arch (3.6% versus 1.7%; P=0.01). After adjustment, a bovine arch was independently associated with increased periprocedural strokes (adjusted odds ratio, 2.16 [95% CI, 1.22-3.83]). At a median follow-up of 2.7 years, the overall incidence of post-TAVR stroke was 6.0% and was significantly higher in patients with a bovine arch even after adjusting for potential confounders (10.5% versus 5.0%; adjusted hazard ratio, 2.11 [95% CI, 1.51-2.93]; P<0.001). CONCLUSIONS: A bovine arch anatomy is associated with a significantly higher risk of periprocedural and long-term stroke after TAVR.

Effect of Beta Blockers on the Hemodynamics and Thrombotic Risk of Coronary Artery Aneurysms in Kawasaki Disease.

This study aims to simulate beta blockers' (BB) effects on coronary artery aneurysms' (CAA) hemodynamics and thrombotic risk in Kawasaki disease (KD). BB are recommended in cases of large aneurysms due to their anti-ischemic effect. Coronary blood flow (CBF) was simulated in KD patient-specific CAA models using computational fluid dynamics. Hemodynamic indices that correlate with thrombotic risk were calculated following two possible responses to BB: (1) preserved coronary flow (third BB generation) and (2) reduction in coronary flow (first and second BB generations) at reduced heart rate. Following CBF reduction scenario, mean TAWSS and HOLMES significantly decreased compared to normal conditions, leading to a potential increase in thrombotic risk. Preserved CBF at lower heart rates, mimicking the response to vasodilating BBs, does not significantly affect local CAA hemodynamics compared with baseline, while achieving the desired anti-ischemic effects. Different BB generations lead to different hemodynamic responses in CAA.

Effect of aortic curvature on bioprosthetic aortic valve performance.

Transvalvular pressure gradient (ΔP) after aortic valve replacement is an important surrogate of aortic bioprostheses performance. Invasive ΔP is often measured after transcatheter aortic valve replacement to exclude patient-prosthetic mismatch. However, invasive aortic pressures are usually recorded in the pressure recovery (PR) zone downstream of the valve, potentially resulting in ΔP underestimation compared to noninvasive measurements. PR was extensively studied in straight ascending aortas. However, the impact of various aortic arch configurations on ΔP has not been explored. PR was assessed in a pulse duplicating simulator at various cardiac conditions of cardiac output, heart rates and pressures. Three different aortic geometries with identical root dimensions but with different aortic arches were used: (1) curvature 1, (2) curvature 2, and (3) straight aortic models. Instantaneous pressure and peak ΔP measurements were recorded incrementally along the models for each cardiac condition. The models with aortic arches produced two distinct PR zones (after the valve and after the aortic arch), whereas the model without an aortic arch produced only one PR zone (after the valve). The trend of the pressure and ΔP curves for each model was independent of the cardiac condition used, but the individually measured pressure magnitudes did change with different conditions. In this study, we illustrated the differences in PR between distinct aortic curvatures and straight aorta. PR affects pressure and ΔP measurements. These effects are clear when recording aortic pressures by catheterization and echocardiography.

Device-Related Thrombus After Left Atrial Appendage Occlusion: Clinical Impact, Predictors, Classification, and Management.

Despite the unprecedented advances in the left atrial appendage occlusion field, device-related thrombus (DRT) remains an unresolved issue with the therapy. This paper aims to provide a state-of-the-art review of the literature on the incidence, clinical impact, predictors and management of DRT and propose a novel classification of DRT and hypoattenuated thickening.

Controlling the Flow Separation in Heart Valves Using Vortex Generators.

A comprehensive computational study is performed to investigate the effectiveness of vortex generators (VGs) applied to mechanical bi-leaflet heart valves. Co-rotating and counter-rotating VG configurations are compared to a control valve without VGs. Detailed flow fields are obtained and used to elucidate the underlying flow physics. It was found that VGs reduce flow separation over the leaflets and hence reduce the Reynolds shear stress (RSS) in the vicinity regions of heart valve. The co-rotating VG configuration demonstrates a better performance compared with the counter-rotating configuration in terms of the RSS, turbulent kinetic energy production and velocity distributions, especially in the peripheral jet flows. The fraction of blood damage in the co-rotating configuration shows a 4.7% reduction in comparison to the control case, while a 3.7% increase is observed in the counter-rotating configuration. The passive flow control technique of applying co-rotating VG illustrates a great potential to help mitigate the hemodynamic factors leading to potential blood damage risk.

Predicting hemodynamic indices in coronary artery aneurysms using response surface method: An application in Kawasaki disease.

BACKGROUND AND OBJECTIVES: Coronary artery aneurysms (CAA), such as those in Kawasaki Disease (KD), induce hemodynamic alterations associated with thrombosis and atherosclerosis. Current clinical routines assess the risk level of the CAA cases based on the Z-Score, which considers the body surface area (BSA) and the CAA's diameter. A full geometric characterization and impact on hemodynamic metrics and their correlation with thrombotic risks have not been systematically investigated. The goal of this study was to investigate the effect of CAA shape indices on local hemodynamics using the response surface method (RSM) through considering KD applications. METHODS: Transient computational fluid dynamics (CFD) simulations have been performed on idealized CAA geometries defined by geometrical ratios combining neck diameter, CAA diameter and CAA length. The results were used to develop full quadratic regression models of the indices using the response surface method (RSM). Validation using patient-specific KD models was performed. RESULTS: The results indicated that the aneurysm diameter is the main determining factor in the thrombotic risk of CAA patients, which is consistent with clinical guidelines. Furthermore, it was observed that in most CAA cases having the same diameter, the one with the shorter length experiences higher RRT values, indicating flow stagnation and circulation. CONCLUSIONS: The developed regression models can be used to ultimately assess the thrombotic risk of CAA cases from the hemodynamic perspective. The applicability of these models was tested on 2 KD patient specific models, with close values achieved between the models and the patient-specific results.

Effects of MitraClip Therapy on Mitral Flow Patterns and Vortex Formation: An In Vitro Study.

MitraClip transcatheter edge-to-edge repair is used to treat mitral regurgitation (MR). While MR is reduced, diastolic left ventricular flows are altered. An in vitro left heart simulator was used to assess a porcine mitral valve in the native, MR, and MR plus MitraClip cases. Velocity, vorticity, and Reynolds shear stress (RSS) were quantified by particle image velocimetry. Peak velocity increased from 1.20 m/s for native to 1.30 m/s with MR. With MitraClip, two divergent jets of 1.18 and 0.61 m/s emerged. Higher vorticity was observed with MR than native and lessened with MitraClip. MitraClip resulted in shear layer formation and downstream vortex formation. Native RSS decreased from 33 Pa in acceleration to 29 Pa at peak flow, then increased to 31 Pa with deceleration. MR RSS increased from 27 Pa in acceleration to 40 Pa at peak flow to 59 Pa during deceleration. MitraClip RSS increased from 79 Pa in acceleration to 162 Pa during peak flow, then decreased to 45 Pa during deceleration. After MitraClip, two divergent jets of reduced velocity emerged, accompanied by shear layers and recirculation. Chaotic flow developed, resulting in elevated RSS magnitude and coverage. Findings help understand consequences of MitraClip on left ventricular flow dynamics.

Flow dynamics of surgical and transcatheter aortic valves: Past to present.

Objective: To perform an in vitro characterization of surgical aortic valves (SAVs) and transcatheter aortic valves (TAVs) to highlight the development of the flow dynamics depending on the type of valve implanted and assess the basic differences in the light of flow turbulence and its effect on blood damage likelihood and hemodynamic parameters that shed light on valve performance. Methods: A Starr-Edwards ball and cage valve of internal diameter 22 mm, a 23-mm Medtronic Hancock II SAV, a 23-mm St Jude Trifecta SAV, a 23-mm St Jude SJM (mechanical valve) SAV, a 26-mm Medtronic Evolut TAV, and a 26-mm Edwards SAPIEN 3 TAV were assessed in a pulse duplicator under physiological conditions. Particle image velocimetry was performed for each valve. Pressure gradient and effective orifice area (EOA) along with velocity flow field, Reynolds shear stress (RSS), and viscous shear stress (VSS) were calculated. Results: The SJM mechanical valve exhibited the greatest EOA (1.96 ± 0.02 cm2), showing superiority of efficiency compared with the same-size Trifecta (1.87 ± 0.07 cm2) and Hancock II (1.05 ± 0.01 cm2) (P < .0001). The TAVs show close EOAs (2.10 ± 0.06 cm2 with Evolut and 2.06 ± 0.03 cm2 with SAPIEN 3; P < .0001). The flow characteristics and behavior downstream of the valves differed depending on the valve type, design, and size. The greater the RSS and VSS the more turbulent the downstream flow. Hancock II displays the greatest range of RSS and VSS magnitudes compared with the same-size Trifecta and SJM. The Evolut displays the greatest range of RSS and VSS compared with the SAPIEN 3. Conclusions: The results of this study shed light on numerous advancements in the design of aortic valve replacement prosthesis and the subsequent hemodynamic variations. Future surgical and transcatheter valve designs should aim at not only concentrating on hemodynamic parameters but also at optimizing downstream flow properties.

Multiple MitraClips: The balancing act between pressure gradient and regurgitation.

OBJECTIVE: Transcatheter mitral valve repair with the MitraClip is used for the symptomatic management of mitral regurgitation (MR). The challenge is reducing MR while avoiding an elevated mitral valve gradient (MVG). This study assesses how multiple MitraClips used to treat MR can affect valve performance. METHODS: Six porcine mitral valves were assessed using an in vitro left heart simulator in the native, moderate-to-severe MR, and severe MR cases. MR cases were tested in the no-MitraClip, 1-MitraClip, and 2-MitraClip configurations. Mitral regurgitant fraction (MRF), MVG, and effective orifice area (EOA) were quantified. RESULTS: Native MRF, MVG, and EOA were 14.22%, 2.59 mm Hg, and 1.64 cm2, respectively. For moderate-to-severe MR, MRF, MVG, and EOA were 34.07%, 3.31 mm Hg, and 2.22 cm2, respectively. Compared with the no-MitraClip case, 1 MitraClip decreased MRF to 18.57% (P < .0001) and EOA to 1.50 cm2 (P = .0002). MVG remained statistically unchanged (3.44 mm Hg). Two MitraClips decreased MRF to 14.26% (P < .0001) and EOA to 1.36 cm2 (P = .0001). MVG remained unchanged (3.29 mm Hg). For severe MR, MRF, MVG, and EOA were 59.79%, 4.98 mm Hg, and 2.73 cm2, respectively. Compared with the no-MitraClip case, 1 MitraClip decreased MRF to 30.72% (P < .0001) and EOA to 1.82 cm2 (P < .0001); MVG remained unchanged (4.03 mm Hg). MVG remained statistically unchanged. Two MitraClips decreased MRF to 23.10% (P < .0001) and EOA to 1.58 cm2 (P < .0001); MVG remained statistically unchanged (3.82 mm Hg). Both MR models yielded no statistical difference between 1 and 2 MitraClips. CONCLUSIONS: There is limited concern regarding elevation of MVG when reducing MR using 1 or 2 MitraClips, although 2 MitraClips did not significantly continue to reduce MRF.

Flow dynamics in the sinus and downstream of third and fourth generation balloon expandable transcatheter aortic valves.

OBJECTIVE: The early success of transcatheter aortic valve (TAV) replacement (TAVR) has fueled further innovations in the field leading to the emergence multiple iterations of TAV designs. Whether these newer designs are associated with similar hemodynamic outcomes remains unknown. Recently, the SAPIEN 3 Ultra valve received FDA approval for use in patients with published clinical outcomes. The aim of this study is (1) to evaluate and compare the flow dynamics downstream of the SAPIEN 3 Ultra and a SAPIEN 3 (2) and to evaluate and compare the resulting sinus hemodynamics and washout characteristics for a complete hemodynamic characterization. METHODS: The hemodynamic assessment was performed in a pulse duplicating system and particle image velocimetry was used to assess the flow dynamics. Pressure gradient (ΔP), effective orifice area (EOA), leakage fraction (LF), velocity in the flow downstream and the sinus, viscous shear stress (VSS) downstream and adjacent to the leaflet in the sinus, and sinus washout were calculated. RESULTS: EOA for the SAPIEN 3 Ultra was 1.81 ± 0.05 cm2 and 1.86 ± 0.05 cm2 with the SAPIEN 3, ΔP with the SAPIEN 3 Ultra was 10.56 ± 0.62 mmHg and 14.73 ± 0.79 mmHg with the SAPIEN 3, and LF with the SAPIEN 3 Ultra was 10.4 ± 0.5% and 9.7 ± 0.4% with the SAPIEN 3 (p<0.05). The instantaneous VSS for both valves ≤15 Pa, which is not sufficient to induce hemolysis, but may lead to platelet activation. RSS - an indicator of blood damage - exceeded 100 Pa at peak systole with both TAVs. The sinus velocity at peak systole was 0.24 ± 0.08 m/s with the SAPIEN 3 Ultra and 0.22 ± 0.10 m/s with the SAPIEN 3. VSS range reached 3.9 Pa with the SAPIEN 3 Ultra and 4.0 Pa with the SAPIEN 3. Complete sinus washout was achieved in ∼1.5 and ∼2.4 cardiac cycles for the SAPIEN 3 Ultra and SAPIEN 3, respectively. CONCLUSION: Compared to its predecessor, the hemodynamic performance and sinus hemodynamics of SAPIEN 3 Ultra are comparable.

Effect of catheter ablation on the hemodynamics of the left atrium : Hemodynamics of ablation.

BACKGROUND: This study aims to evaluate the impact of catheter ablation for atrial fibrillation (AF) on left atrial (LA) flow dynamics and geometrical changes. METHODS: This exploratory study included computational flow simulations from 10 patients who underwent catheter ablation for AF. Complete cardiac cycle dataset was simulated before and after ablation using computational fluid dynamics. The study main endpoints were the changes in LA volume, LA velocity, LA wall shear stress (WSS), circulation (Γ), vorticity, pulmonary vein (PV) ostia area, and LA vortices before and after ablation. RESULTS: There was an average decrease in LA volume (11.58 ± 15.17%) and PV ostia area (16.6 ± 21.41%) after ablation. A non-uniform trend of velocity and WSS changes were observed after ablation. Compared with pre-ablation, 4 patients exhibited lower velocities, WSS distributions, and a decreased Γ (> 8.5%), while 6 developed higher velocities and WSS distributions. These geometrical changes dictated different flow mixing in the LA and distinct vortex patterns, characterized by different spinning velocities, vorticities, and rotational directions. Regions with q-criterion > 0 were found to be dominant in the LA, indicating prevalent rotational vortex structures. CONCLUSION: Catheter ablation for AF induced different geometrical changes on the LA and the PVs, therefore influencing flow mixing and vortex patterns in the LA, in addition to overall velocity and WSS distribution. Further exploration of the impact of catheter ablation on intracardiac flow dynamics is warranted to discern patterns that may correlate with clinical outcomes.

Impact of calcific aortic valve disease on valve mechanics.

The aortic valve is a highly dynamic structure characterized by a transvalvular flow that is unsteady, pulsatile, and characterized by episodes of forward and reverse flow patterns. Calcific aortic valve disease (CAVD) resulting in compromised valve function and increased pressure overload on the ventricle potentially leading to heart failure if untreated, is the most predominant valve disease. CAVD is a multi-factorial disease involving molecular, tissue and mechanical interactions. In this review, we aim at recapitulating the biomechanical loads on the aortic valve, summarizing the current and most recent research in the field in vitro, in-silico, and in vivo, and offering a clinical perspective on current strategies adopted to mitigate or approach CAVD.