Laser ablation for preventing coronary obstruction and maintaining coronary access in redo-TAVR: A proof of concept.

Background: Redo-transcatheter aortic valve replacement (TAVR) is a promising treatment for transcatheter aortic valve degeneration, becoming increasingly relevant with an aging population. In redo-TAVR, the leaflets of the initial (index) transcatheter aortic valve (TAV) are displaced vertically when the second TAV is implanted, creating a cylindrical cage that can impair coronary cannulation and flow. Preventing coronary obstruction and maintaining coronary access is essential, especially in young and low-risk patients undergoing TAVR.

The Measurement of Bovine Pericardium Density and Its Implications on Leaflet Stress Distribution in Bioprosthetic Heart Valves.

Purpose: Bioprosthetic Heart Valves (BHVs) are widely used in clinical practice, showing promising outcomes. Computational modeling offers a valuable tool for quantitatively characterizing BHVs. To ensure the accuracy of computational models, it is crucial to consider precise leaflet properties, including mechanical properties and density.

On the Three-dimensionality of Flow in the Neo-sinus and its Implications for Subclinical Leaflet Thrombosis.

Objectives: Subclinical leaflet thrombosis is a silent phenomenon commonly observed following transcatheter aortic valve implantation (TAVI). Leaflet thrombosis is associated with ischaemic complications and structural valve deterioration. Prior studies have shown that blood stasis in neo-sinus contributes to the initiation and growth of subclinical leaflet thrombosis.

Subclinical Leaflet Thrombosis in Supra-annular Transcatheter Aortic Valves: the Role of Leaflet Design.

Subclinical leaflet thrombosis has been increasingly observed in patients undergoing transcatheter aortic valve replacement. Intra-annular transcatheter aortic valves (TAVs) have a larger neo-sinus volume than supra-annular devices and are potentially at a higher risk of hypoattenuated leaflet thickening (HALT). However, clinical data from randomized clinical trials have shown that approximately one-third of patients undergoing TAVR with intra- or supra-annular devices develop HALT in 1 year.

Structural analysis of regional transcatheter aortic valve underexpansion and its implications for subclinical leaflet thrombosis.

Subclinical leaflet thrombosis has been increasingly recognized following transcatheter aortic valve replacement (TAVR). Determining the risk factors is vital in preventing clinical leaflet thrombosis and ensuring long-term value durability. Clinical data have indicated that regional stent under-expansion of transcatheter aortic valves (TAVs), particularly self-expanding devices, may be associated with an increased risk of subclinical leaflet thrombosis.

Transcatheter aortic valve replacement in bicuspid valves: The synergistic effects of eccentric and incomplete stent deployment.

Bicuspid aortic valve is a congenital cardiac anomaly and common etiology of aortic stenosis. Given the positive outcomes of transcatheter aortic valve replacement (TAVR) in low-risk patients, TAVR will become more prevalent in the future in the treatment of severe bicuspid valve stenosis. However, asymmetrical bicuspid valve anatomy and calcification can prevent the circular and complete expansion of transcatheter aortic valves (TAVs).

Incomplete expansion of transcatheter aortic valves is associated with propensity for valve thrombosis.

Objectives: Clinical and subclinical leaflet thromboses are increasingly recognized complications following transcatheter aortic valve replacement. Identification of the risk factors is important to mitigate the occurrence of leaflet thrombosis in transcatheter aortic valves (TAVs) and ensure their long-term function. The goal of this study was to determine the effect of incomplete expansion of TAVs on the likelihood of leaflet thrombosis following transcatheter aortic valve replacement.

A geometry optimization framework for transcatheter heart valve leaflet design.

Transcatheter aortic valve replacement (TAVR) is an established treatment for patients with severe symptomatic aortic stenosis. It is known and recognized that leaflet geometry has a key role in structural and hemodynamic performance of bioprosthetic heart valves. Excessive mechanical stress on the leaflets will lead to accelerated tissue degeneration and diminished long-term valve durability.

Clinical Valve Thrombosis After Transcatheter Aortic Valve-in-Valve Implantation.

Background Limited data exist on clinical valve thrombosis after transcatheter aortic valve-in-valve (ViV) implantation. Our objective was to determine the incidence, timing, clinical characteristics, and treatment outcomes of patients diagnosed with clinical ViV thrombosis. Methods and Results Centers participating in the Valve-in-Valve International Data Registry were surveyed for thrombosis cases, and clinical valve thrombosis was defined based on a combination of the presence of new valve dysfunction and an imaging evidence of leaflet thrombosis.

A Non-Invasive Material Characterization Framework for Bioprosthetic Heart Valves.

Computational modeling and simulation has become more common in design and development of bioprosthetic heart valves. To have a reliable computational model, considering accurate mechanical properties of biological soft tissue is one of the most important steps. The goal of this study was to present a non-invasive material characterization framework to determine mechanical propertied of soft tissue employed in bioprosthetic heart valves.

Fluid Dynamic Characterization of Transcatheter Aortic Valves Using Particle Image Velocimetry.

Transcatheter aortic valves provide superior systolic hemodynamic performance in terms of valvular pressure gradient and effective orifice area compared with equivalent size surgical bioprostheses. However, in depth investigation of the flow field structures is of interest to examine the flow field characteristics and provide experimental evidence necessary for validation of computational models. The goal of this study was to compare flow field characteristics of the three most commonly used transcatheter and surgical valves using phase-locked particle image velocimetry (PIV).

High resolution three-dimensional strain mapping of bioprosthetic heart valves using digital image correlation.

Transcatheter aortic valve replacement (TAVR) is a safe and effective treatment option for patients deemed at high and intermediate risk for surgical aortic valve replacement. Similar to surgical aortic valves (SAVs), transcatheter aortic valves (TAVs) undergo calcification and mechanical wear over time. However, to date, there have been limited publications on the long-term durability of TAV devices.

Stress Analysis of Transcatheter Aortic Valve Leaflets Under Dynamic Loading: Effect of Reduced Tissue Thickness.

Background And Aim Of The Study: In order to accommodate transcatheter valves to miniaturized catheters, the leaflet thickness must be reduced to a value which is typically less than that of surgical bioprostheses. The study aim was to use finite-element simulations to determine the impact of the thickness reduction on stress and strain distribution.

Methods: A 23 mm transcatheter aortic valve (TAV) was modelled based on the Edwards SAPIEN XT (Edwards Lifesciences, Irvine, CA, USA).

Supra-annular Valve-in-Valve implantation reduces blood stasis on the transcatheter aortic valve leaflets.

Leaflet thrombosis following transcatheter aortic valve replacement (TAVR) and Valve-in-Valve (ViV) procedures has been increasingly recognized. This study aimed to investigate the effect of positioning of the transcatheter aortic valve (TAV) in ViV setting on the flow dynamics aspect of post-ViV thrombosis by quantifying the blood stasis in the intra-annular and supra-annular settings. To that end, two idealized computational models, representing ViV intra-annular and supra-annular positioning of a TAV were developed in a patient-specific geometry.

Effect of reduced cardiac output on blood stasis on transcatheter aortic valve leaflets: implications for valve thrombosis.

Aims: There is an increasing awareness of leaflet thrombosis following transcatheter aortic valve implantation (TAVI) and valve-in-valve (ViV) procedures. Nevertheless, the predisposing factors affecting transcatheter aortic valve (TAV) thrombosis have remained unclear. This study aimed to quantify the effects of reduced cardiac output (CO) on blood stasis on the TAV leaflets as a permissive factor for valve thrombosis.

Blood Stasis on Transcatheter Valve Leaflets and Implications for Valve-in-Valve Leaflet Thrombosis.

Background: Leaflet thrombosis after valve-in-valve (ViV) procedure has been increasingly recognized. This study aimed to investigate the flow dynamics aspect of leaflet thrombosis by quantifying the blood stasis on the noncoronary and coronary leaflets of a surgical aortic valve (SAV) and a transcatheter aortic valve (TAV) in a ViV setting.

Methods: Two computational models, representing a SAV and a TAV in ViV setting, were developed in a patient-specific geometry.

Effect of transcatheter aortic valve size and position on valve-in-valve hemodynamics: An in vitro study.

Objective: Transcatheter heart valve implantation in failed aortic bioprostheses (valve-in-valve [ViV]) is an increasingly used therapeutic option for high-risk patients. However, high postprocedural gradients are a significant limitation of aortic ViV. Our objective was to evaluate Medtronic CoreValve Evolut R ViV hemodynamics in relation to the degree of device oversizing and depth of implantation.

Valve thrombosis following transcatheter aortic valve replacement: significance of blood stasis on the leaflets.

Objectives: Leaflet thrombosis following transcatheter aortic valve replacement (TAVR) and valve-in-valve (ViV) procedures has been increasingly recognized. However, the factors affecting the post-TAVR/ViV thrombosis are not fully understood. This study aimed to investigate the effect of the geometric confinement of transcatheter aortic valve (TAV) on blood residence time (BRT) on the TAV leaflets and in turn on the post-TAVR valve thrombosis.

Biomechanical Properties and Microstructure of Heart Chambers: A Paired Comparison Study in an Ovine Model.

Mechanical properties of the cardiac tissue play an important role in normal heart function. The goal of this study was to determine the passive mechanical properties of all heart chambers through a paired comparison study in an ovine model. Ovine heart was used due its physiological and anatomical similarities to human heart.

In vitro evaluation of implantation depth in valve-in-valve using different transcatheter heart valves.

Aims: Transcatheter heart valve (THV) implantation in failed bioprosthetic valves (valve-in-valve [ViV]) offers an alternative therapy for high-risk patients. Elevated post-procedural gradients are a significant limitation of aortic ViV. Our objective was to assess the relationship between depth of implantation and haemodynamics.

Characterization of three-dimensional anisotropic heart valve tissue mechanical properties using inverse finite element analysis.

Computational modeling has an important role in design and assessment of medical devices. In computational simulations, considering accurate constitutive models is of the utmost importance to capture mechanical response of soft tissue and biomedical materials under physiological loading conditions. Lack of comprehensive three-dimensional constitutive models for soft tissue limits the effectiveness of computational modeling in research and development of medical devices.

Surgical Trauma Caused by Different Abdominal Access Routes-Comparison of Open Surgical, Laparoscopic, and NOTES Transgastric Techniques in a Porcine Model.

Background: Investigations indicate that natural orifice translumenal endoscopic surgery (NOTES) procedures induce a less pronounced postoperative inflammatory response than open or laparoscopic surgery, inflicting less trauma. In NOTES procedures, no skin incision is performed. We compare the inflammatory response added by the type of incision by measuring C-reactive protein (CRP) and tumors necrosis factor-alfa (TNF-α).

Flow-Induced Damage to Blood Cells in Aortic Valve Stenosis.

Valvular hemolysis and thrombosis are common complications associated with stenotic heart valves. This study aims to determine the extent to which hemodynamics induce such traumatic events. The viscous shear stress downstream of a severely calcified bioprosthetic valve was evaluated via in vitro 2D particle image velocimetry measurements.