Polymeric heart valves for surgical implantation, catheter-based technologies and heart assist devices

Emergence of graphene as a novel nanomaterial for cardiovascular applications

Cardiovascular diseases (CDs) are the foremost cause of death worldwide. Several promising therapeutic methods have been developed for this approach, including pharmacological, surgical intervention, cell therapy, or biomaterial implantation since heart tissue is incapable of regenerating and healing on its own. The best treatment for heart failure to date is heart transplantation and invasive surgical intervention, despite their invasiveness, donor limitations, and the possibility of being rejected by the patient's immune system. To address these challenges, research is being conducted on less invasive and efficient methods. Consequently, graphene-based materials (GBMs) have attracted a great deal of interest in the last decade because of their exceptional mechanical, electrical, chemical, antibacterial, and biocompatibility properties. An overview of GBMs' applications in the cardiovascular system has been presented in this article. Following a brief explanation of graphene and its derivatives' properties, the potential of GBMs to improve and restore cardiovascular system function by using them as cardiac tissue engineering, stents, vascular bypass grafts,and heart valve has been discussed.

Comparison study of surface-initiated hydrogel coatings with distinct side-chains for improving biocompatibility of polymeric heart valves

Polymeric heart valves (PHVs) present a promising alternative for treating valvular heart diseases with satisfactory hydrodynamics and durability against structural degeneration. However, the cascaded coagulation, inflammatory responses, and calcification in the dynamic blood environment pose significant challenges to the surface design of current PHVs. In this study, we employed a surface-initiated polymerization method to modify polystyrene-block-isobutylene-block-styrene (SIBS) by creating three hydrogel coatings: poly(2-methacryloyloxy ethyl phosphorylcholine) (pMPC), poly(2-acrylamido-2-methylpropanesulfonic acid) (pAMPS), and poly(2-hydroxyethyl methacrylate) (pHEMA). These hydrogel coatings dramatically promoted SIBS's hydrophilicity and blood compatibility at the initial state. Notably, the pMPC and pAMPS coatings maintained a considerable platelet resistance performance after 12 h of sonication and 10 000 cycles of stretching and bending. However, the sonication process induced visible damage to the pHEMA coating and attenuated the anti-coagulation property. Furthermore, the in vivo subcutaneous implantation studies demonstrated that the amphiphilic pMPC coating showed superior anti-inflammatory and anti-calcification properties. Considering the remarkable stability and optimal biocompatibility, the amphiphilic pMPC coating constructed by surface-initiated polymerization holds promising potential for modifying PHVs.

Aortic Valve Engineering Advancements: Precision Tuning with Laser Sintering Additive Manufacturing of TPU/TPE Submillimeter Membranes

Synthetic biomaterials play a crucial role in developing tissue-engineered heart valves (TEHVs) due to their versatile mechanical properties. Achieving the right balance between mechanical strength and manufacturability is essential. Thermoplastic polyurethanes (TPUs) and elastomers (TPEs) garner significant attention for TEHV applications due to their notable stability, fatigue resistance, and customizable properties such as shear strength and elasticity. This study explores the additive manufacturing technique of selective laser sintering (SLS) for TPUs and TPEs to optimize process parameters to balance flexibility and strength, mimicking aortic valve tissue properties. Additionally, it aims to assess the feasibility of printing aortic valve models with submillimeter membranes. The results demonstrate that the SLS-TPU/TPE technique can produce micrometric valve structures with soft shape memory properties, resembling aortic tissue in strength, flexibility, and fineness. These models show promise for surgical training and manipulation, display intriguing echogenicity properties, and can potentially be personalized to shape biocompatible valve substitutes.

Early Feasibility Study of a Hybrid Tissue-Engineered Mitral Valve in an Ovine Model

Tissue engineering aims to overcome the current limitations of heart valves by providing a viable alternative using living tissue. Nevertheless, the valves constructed from either decellularized xenogeneic or purely biologic scaffolds are unable to withstand the hemodynamic loads, particularly in the left ventricle. To address this, we have been developing a hybrid tissue-engineered heart valve (H-TEHV) concept consisting of a nondegradable elastomeric scaffold enclosed in a valve-like living tissue constructed from autologous cells. We developed a 21 mm mitral valve scaffold for implantation in an ovine model. Smooth muscle cells/fibroblasts and endothelial cells were extracted, isolated, and expanded from the animal's jugular vein. Next, the scaffold underwent a sequential coating with the sorted cells mixed with collagen type I. The resulting H-TEHV was then implanted into the mitral position of the same sheep through open-heart surgery. Echocardiography scans following the procedure revealed an acceptable valve performance, with no signs of regurgitation. The valve orifice area, measured by planimetry, was 2.9 cm2, the ejection fraction reached 67%, and the mean transmitral pressure gradient was measured at 8.39 mmHg. The animal successfully recovered from anesthesia and was transferred to the vivarium. Upon autopsy, the examination confirmed the integrity of the H-TEHV, with no evidence of tissue dehiscence. The preliminary results from the animal implantation suggest the feasibility of the H-TEHV.

Mechanical valve replacement for patients with rheumatic heart disease: the reality of INR control in Africa and beyond

The majority of patients requiring heart valve replacement in low- to middle-income countries (LMICs) need it for rheumatic heart disease (RHD). While the young age of such patients largely prescribes replacement with mechanical prostheses, reliable anticoagulation management is often unattainable under the prevailing socioeconomic circumstances. Cases of patients with clotted valves presenting for emergency surgery as a consequence of poor adherence to anticoagulation control are frequent. The operative mortality rates of reoperations for thrombosed mechanical valves are several times higher than those for tissue valves, and long-term results are also disappointing. Under-anticoagulation prevails in these regions that has clearly been linked to poor international normalised ratio (INR) monitoring. In industrialised countries, safe anticoagulation is defined as >60%-70% of the time in the therapeutic range (TTR). In LMICs, the TTR has been found to be in the range of twenty to forty percent. In this study, we analysed >20,000 INR test results of 552 consecutive patients receiving a mechanical valve for RHD. Only 27% of these test results were in the therapeutic range, with the vast majority (61%) being sub-therapeutic. Interestingly, the post-operative frequency of INR tests of one every 3-4 weeks in year 1 had dropped to less than 1 per year by year 7. LMICs need to use clinical judgement and assess the probability of insufficient INR monitoring prior to uncritically applying Western guidelines predominantly based on chronological age. The process of identification of high-risk subgroups in terms of non-adherence to anticoagulation control should take into account both the adherence history of >50% of patients with RHD who were in chronic atrial fibrillation prior to surgery as well as geographic and socioeconomic circumstances.

Three-dimensional fluid-structure interaction simulation of the Wheatley aortic valve

Valvular heart diseases (such as stenosis and regurgitation) are recognized as a rapidly growing cause of global deaths and major contributors to disability. The most effective treatment for these pathologies is the replacement of the natural valve with a prosthetic one. Our work considers an innovative design for prosthetic aortic valves that combines the reliability and durability of artificial valves with the flexibility of tissue valves. It consists of a rigid support and three polymer leaflets which can be cut from an extruded flat sheet, and is referred to hereafter as the Wheatley aortic valve (WAV). As a first step towards the understanding of the mechanical behavior of the WAV, we report here on the implementation of a numerical model built with the ICFD multi-physics solver of the LS-DYNA software. The model is calibrated and validated using data from a basic pulsatile-flow experiment in a water-filled straight tube. Sensitivity to model parameters (contact parameters, mesh size, etc.) and to design parameters (height, material constants) is studied. The numerical data allow us to describe the leaflet motion and the liquid flow in great detail, and to investigate the possible failure modes in cases of unfavorable operational conditions (in particular, if the leaflet height is inadequate). In future work the numerical model developed here will be used to assess the thrombogenic properties of the valve under physiological conditions.

Tailoring of Silicone Urethane Methacrylate Resin for Vat Photopolymerization-Based 3D Printing of Shape Memory Polymers

Polydimethylsiloxane (PDMS) or silicone elastomers have garnered considerable attention in the field of medical device applications due to their superior thermal stability. However, conventional manufacturing techniques for silicone elastomers suffer from drawbacks such as cost, lengthy production time, and inherent difficulties in fabricating complex structures. To address these limitations, photosensitive polydimethylsiloxane urethane methacrylate (PDMSUMA) oligomers were synthesized, and their curing behaviors were specifically investigated for vat photopolymerization 3D printing applications. The study focused on exploring the impact of weight ratios between poly(ethylene glycol) dimethacrylate (PEGDMA) and 2-hydroxyethyl methacrylate (HEMA) in the PDMSUMA resin formulation. The addition of PEGDMA as a reactive diluent was found to enhance the printability of the PDMSUMA resin and decrease its viscosity. Thermal, mechanical, and shape memory properties of the 3D-printed specimens were examined. Our findings demonstrate the potential of PDMSUMA resins for developing customizable shape memory materials with tailored properties.

In vitro hemodynamics of fabric composite membrane for cardiac valve prosthesis replacement

This study aimed to investigate the hemodynamics of a novel fabric composite that can be used as a substitute for bovine pericardium. The structure is composed of ultrahigh molecular weight polyethylene (UHMWPE) fabric coated with thermoplastic polyurethane (TPU) membranes on both sides. In vitro experiments were carried out on two composite valve samples with different specifications and a bovine pericardial one with the same dimension and structure. Hemodynamic properties including the effective orifice area (EOA) and regurgitant fraction (RF) were obtained and compared through pulsatile-flow testing in a pulse duplicator. Using the particle image velocimetry (PIV) technique, frames of the downstream velocity field in the aortic valve chamber were captured during cardiac cycles. Then, the field of Reynolds shear stress (RSS), viscous shear stress (VSS), and turbulent kinetic energy (TKE) at peak systole were calculated. A fluid-structure interaction (FSI) model has also been used to verify the pulsatile-flow testing. Compared with the bovine pericardial valve, composite valves have nosuperiority regarding EOA and RF due to their slightly higher rigidity. However, shear stresses of composite valves were lower than those of the bovine pericardial valve indicating more stable blood flows, which means that composite leaflets have the potential to reduce the risks of thrombosis and hemolysis induced by the mechanical contact between the blood flow and leaflets of valve prostheses.

Structural study of a polymeric aortic valve prosthesis. Analysis for a hyperelastic material

This work presents a structural computational simulation of a polymeric aortic valve prosthesis, made with a hyperelastic material (Styrene-Ethylene/Propylene-Styrene). The valve has a suture ring, three pillars placed at 120° and three leaflets. The analysis is based on a modification over previous designs consisting in a fillet concave surface to avoid stress concentration at the junctions between leaflets and pillars. Three shapes were simulated. The first one was used to validate the computational method by comparison of the results with a recent paper. The second shape was designed to show that a fillet or "rounding" can be beneficial to the stress leaflet reduction. The third shape was also designed to show that the reduction of leaflet thickness and intercommissural distance between leaflets at the pillar junctions improves the valve opening and closure. The use of fillet with a 0.5 mm radius, reduced 26.5% the maximum Von Mises stresses for the second shape and 33.9% for the third shape. Additionally, for the latter, the opening area was not affected for the high stiffness due to fillet. The results -mainly for the third shape-are promising and give rise to future studies: further shape optimization, analysis for other materials and valve simulation under pathological loads.

Evaluation of pliable bioresorbable, elastomeric aortic valve prostheses in sheep during 12 months post implantation

Pliable microfibrous, bioresorbable elastomeric heart valve prostheses are investigated in search of sustainable heart valve replacement. These cell-free implants recruit cells and trigger tissue formation on the valves in situ. Our aim is to investigate the behaviour of these heart valve prostheses when exposed to the high-pressure circulation. We conducted a 12-month follow-up study in sheep to evaluate the in vivo functionality and neo-tissue formation of these valves in the aortic position. All valves remained free from endocarditis, thrombotic complications and macroscopic calcifications. Cell colonisation in the leaflets was mainly restricted to the hinge area, while resorption of synthetic fibers was limited. Most valves were pliable and structurally intact (10/15), however, other valves (5/15) showed cusp thickening, retraction or holes in the leaflets. Further research is needed to assess whether in-situ heart valve tissue engineering in the aortic position is possible or whether non-resorbable synthetic pliable prostheses are preferred.

Monitoring the macrophage response towards biomaterial implants using label-free imaging

Understanding the immune system's foreign body response (FBR) is essential when developing and validating a biomaterial. Macrophage activation and proliferation are critical events in FBR that can determine the material's biocompatibility and fate in vivo. In this study, two different macro-encapsulation pouches intended for pancreatic islet transplantation were implanted into streptozotocin-induced diabetes rat models for 15 days. Post-explantation, the fibrotic capsules were analyzed by standard immunohistochemistry as well as non-invasive Raman microspectroscopy to determine the degree of FBR induced by both materials. The potential of Raman microspectroscopy to discern different processes of FBR was investigated and it was shown that Raman microspectroscopy is capable of targeting ECM components of the fibrotic capsule as well as pro and anti-inflammatory macrophage activation states, in a molecular-sensitive and marker-independent manner. In combination with multivariate analysis, spectral shifts reflecting conformational differences in Col I were identified and allowed to discriminate fibrotic and native interstitial connective tissue fibers. Moreover, spectral signatures retrieved from nuclei demonstrated changes in methylation states of nucleic acids in M1 and M2 phenotypes, relevant as indicator for fibrosis progression. This study could successfully implement Raman microspectroscopy as complementary tool to study in vivo immune-compatibility providing insightful information of FBR of biomaterials and medical devices, post-implantation.

Research Progress on Stimulus-Responsive Polymer Nanocarriers for Cancer Treatment

As drug carriers for cancer treatment, stimulus-responsive polymer nanomaterials are a major research focus. These nanocarriers respond to specific stimulus signals (e.g., pH, redox, hypoxia, enzymes, temperature, and light) to precisely control drug release, thereby improving drug uptake rates in cancer cells and reducing drug damage to normal cells. Therefore, we reviewed the research progress in the past 6 years and the mechanisms underpinning single and multiple stimulus-responsive polymer nanocarriers in tumour therapy. The advantages and disadvantages of various stimulus-responsive polymeric nanomaterials are summarised, and the future outlook is provided to provide a scientific and theoretical rationale for further research, development, and utilisation of stimulus-responsive nanocarriers.

In Vitro Proof of Concept of a First-Generation Growth-Accommodating Heart Valved Conduit for Pediatric Use

Currently available heart valve prostheses have no growth potential, requiring children with heart valve diseases to endure multiple valve replacement surgeries with compounding risks. This study demonstrates the in vitro proof of concept of a biostable polymeric trileaflet valved conduit designed for surgical implantation and subsequent expansion via transcatheter balloon dilation to accommodate the growth of pediatric patients and delay or avoid repeated open-heart surgeries. The valved conduit is formed via dip molding using a polydimethylsiloxane-based polyurethane, a biocompatible material shown here to be capable of permanent stretching under mechanical loading. The valve leaflets are designed with an increased coaptation area to preserve valve competence at expanded diameters. Four 22 mm diameter valved conduits are tested in vitro for hydrodynamics, balloon dilated to new permanent diameters of 23.26 ± 0.38 mm, and then tested again. Upon further dilation, two valved conduits sustain leaflet tears, while the two surviving devices reach final diameters of 24.38 ± 0.19 mm. After each successful dilation, the valved conduits show increased effective orifice areas and decreased transvalvular pressure differentials while maintaining low regurgitation. These results demonstrate concept feasibility and motivate further development of a polymeric balloon-expandable device to replace valves in children and avoid reoperations.

Mechanical behaviors of high-strength fabric composite membrane designed for cardiac valve prosthesis replacement

Bovine pericardium has been commonly used as leaflets in cardiac valve prosthesis replacement for decades because of its good short-term hemocompatibility and hemodynamic performance. However, fatigue, abrasion, permanent deformation, calcification, and many other failure modes have been reported as well. The degradation of the performance will have a serious impact on the function of valve prostheses, posing a risk to the patient's health. This study aimed to introduce a flexible fabric composite with better mechanical performance such that it can be employed as a substitute material for bioprosthetic valve leaflets. This composite has a multilayered thin film structure made of ultrahigh molecular weight polyethylene (UHMWPE) fabric and thermoplastic polyurethane (TPU) membranes. The mechanical properties of three specifications with different design parameters were tested. The tensile strength, shear behavior, tear resistance, and bending stiffness of the composites were characterized and compared to those of bovine pericardium. A constitutive model was also established to describe the composites' mechanical behaviors and predict their strength. According to the results of the tests, the composite could maintain a flexible bending stiffness with high in-plane tensile strength and tear strength. Therefore, bioprosthetic valve made of this substitute material can withstand harsher loads in the blood flow environment than those made of bovine pericardium. Moreover, all these test results and constitutive models can be used in future research to evaluate hemodynamic performance and clinical applications of fabric composite valve prostheses.

Polymeric prosthetic heart valves: A review of current technologies and future directions

Valvular heart disease is an important source of cardiovascular morbidity and mortality. Current prosthetic valve replacement options, such as bioprosthetic and mechanical heart valves are limited by structural valve degeneration requiring reoperation or the need for lifelong anticoagulation. Several new polymer technologies have been developed in recent years in the hope of creating an ideal polymeric heart valve substitute that overcomes these limitations. These compounds and valve devices are in various stages of research and development and have unique strengths and limitations inherent to their properties. This review summarizes the current literature available for the latest polymer heart valve technologies and compares important characteristics necessary for a successful valve replacement therapy, including hydrodynamic performance, thrombogenicity, hemocompatibility, long-term durability, calcification, and transcatheter application. The latter portion of this review summarizes the currently available clinical outcomes data regarding polymeric heart valves and discusses future directions of research.

Flaw-insensitive fatigue resistance of chemically fixed collagenous soft tissues

Bovine pericardium (BP) has been used as leaflets of prosthetic heart valves. The leaflets are sutured on metallic stents and can survive 400 million flaps (~10-year life span), unaffected by the suture holes. This flaw-insensitive fatigue resistance is unmatched by synthetic leaflets. We show that the endurance strength of BP under cyclic stretch is insensitive to cuts as long as 1 centimeter, about two orders of magnitude longer than that of a thermoplastic polyurethane (TPU). The flaw-insensitive fatigue resistance of BP results from the high strength of collagen fibers and soft matrix between them. When BP is stretched, the soft matrix enables a collagen fiber to transmit tension over a long length. The energy in the long length dissipates when the fiber breaks. We demonstrate that a BP leaflet greatly outperforms a TPU leaflet. It is hoped that these findings will aid the development of soft materials for flaw-insensitive fatigue resistance.

Tailoring crystallinity for hemocompatible and durable PEEK cardiovascular implants

Polymers have the potential to replace metallic or bioprosthetic heart valve components due to superior durability and inertness while allowing for native tissue-like flexibility. Despite these appealing properties, certain polymers such as polyetheretherketone (PEEK) have issues with hemocompatibility, which have previously been addressed through assorted complex processes. In this paper, we explore the enhancement of PEEK hemocompatibility with polymer crystallinity. Amorphous, semi-crystalline and crystalline PEEK are investigated in addition to a highly crystalline carbon fiber (CF)/PEEK composite material (CFPEEK). The functional group density of the PEEK samples is determined, showing that higher crystallinity results in increased amount of surface carbonyl functional groups. The increase of crystallinity (and negatively charged groups) appears to cause significant reductions in platelet adhesion (33 vs. 1.5 % surface coverage), hemolysis (1.55 vs. 0.75 %∙cm^-2), and thrombin generation rate (4840 vs. 1585 mU/mL/min/cm²). In combination with the hemocompatibility study, mechanical characterization demonstrates that tailoring crystallinity is a simple and effective method to control both hemocompatibility and mechanical performance of PEEK. Furthermore, the results display that CFPEEK composite performed very well in all categories due to its enhanced crystallinity and complete carbon encapsulation, allowing the unique properties of CFPEEK to empower new concepts in cardiovascular device design.

Synthesis of High-Molecular-Weight and Strength Polyisobutylene-Based Polyurethane and Its Use for the Development of a Synthetic Heart Valve

Under optimized synthesis conditions, for the first time, polyisobutylene-based polyurethane (PIB-PU) is prepared with 70% PIB soft segment (i.e., a bioinert and calcification-resistant PU) with M_n > 100 000 Da, 32 MPa ultimate strength, and 630% elongation. The key parameters for this achievement are a) the precise stoichiometry of the polyurethane forming reaction, specifically the use of highly purified di-isocyanate (4,4'-methylene-bis (phenyl isocyanate), MDI), and b) the increased solid content of the synthesis solution to the limit beyond which increased viscosity prevents stirring. The shape of the stress-strain trace of PIB-PU indicates a two-step failure starting with a reversible elastic (Hookean) region up to ≈50% yield, followed by a slower linearly increasing high-modulus-deformation region suggesting the strengthening of PIB soft segments by entanglement/catenation, and the hard segments by progressively ordering urethane domains. This PIB-PU is a candidate for a fully synthetic bioprosthetic heart valve since preliminary studies show that PIB-PU has impressive fatigue life.

What's New with TAVR? An Update on Device Technology

Over the last 20 years, transcatheter aortic valve replacement (TAVR) has revolutionized the management of aortic stenosis and has become the standard of care across the entire spectrum of surgical risk. Expansion of TAVR in treating younger, lower-risk patients with longer life expectancies, and treating earlier in the disease process, has seen a continuous evolution in device technology, with several next-generation transcatheter heart valves developed to minimize procedural complications and improve patient outcomes. This review provides an update on the latest advances in transcatheter delivery systems, devices, and leaflet technology.

Single-cell RNA sequencing reveals the diversity and biology of valve cells in cardiac valve disease

From highly aligned extracellular fibrils to the cells, a multilevel ordered hierarchy in valve leaflets is crucial for their biological function. Cardiac valve pathology most frequently involves a disruption in normal structure-function correlations through abnormal and complex interaction of cells, extracellular matrix, and their environment. At present, effective treatment for valve disease is limited and frequently ends with surgical repair or replacement with a mechanical or artificial biological cardiac valve, which comes with insuperable complications for many high-risk patients including aged and pediatric populations. Therefore, there is a critical need to fully appreciate the pathobiology of valve disease in order to develop better, alternative therapies. To date, the majority of studies have focused on delineating valve disease mechanisms at the cellular level. However, the cellular heterogeneity and function is still unclear. In this review, we summarize the body of work on valve cells, with a particular focus on the discoveries about valve cells heterogeneity and functions using single-cell RNA sequencing. We conclude by discussing state-of-the-art strategies for deciphering heterogeneity of these complex cell types, and argue this knowledge could translate into the improved personalized treatment of cardiac valve disease.

Construction of vascularized tissue-engineered breast with dual angiogenic and adipogenic micro-tissues

Hydrogel-based micro-tissue engineering technique, a bottom-up approach, is promising in constructing soft tissue of large size with homogeneous spatial distribution and superior regeneration capacity compared to the top-down approach. However, most of the studies employed micro-tissues with simple mesenchymal stem cells, which could hardly meet the growth of matrix and vessels. Therefore, we recommend a dual micro-tissues assembly strategy to construct vascularized tissue-engineered breast grafts (TEBGs). Adipose micro-tissues (AMs) and vessel micro-tissues (VMs) were fabricated by seeding adipose-derived stem cells (ADSCs) and human umbilical vein endothelial cells (HUVECs) on collagen microgels (COLs) with a uniform diameter of ∼250 ​μm, respectively. TEBGs were constructed by injecting the dual micro-tissues into 3D printed breast-like Thermoplastic Urethane (TPU) scaffolds, then implanted into the subcutaneous pockets on the back of nude mice. After 3 months of implantation, TEBGs based on dual micro-tissues performed larger volume of adipose tissue regeneration and neo-vessel formation compared to TEBGs based on single AMs. This study extends the application of micro-tissue engineering technique for the construction of soft grafts, and is expected to be useful for creating heterogeneous tissue constructs in the future.

Development of Innovative Biomaterials and Devices for the Treatment of Cardiovascular Diseases

Cardiovascular diseases have become the leading cause of death worldwide. The increasing burden of cardiovascular diseases has become a major public health problem and how to carry out efficient and reliable treatment of cardiovascular diseases has become an urgent global problem to be solved. Recently, implantable biomaterials and devices, especially minimally invasive interventional ones, such as vascular stents, artificial heart valves, bioprosthetic cardiac occluders, artificial graft cardiac patches, atrial shunts, and injectable hydrogels against heart failure, have become the most effective means in the treatment of cardiovascular diseases. Herein, an overview of the challenges and research frontier of innovative biomaterials and devices for the treatment of cardiovascular diseases is provided, and their future development directions are discussed.

Adhesive and Self-Healing Polyurethanes with Tunable Multifunctionality

Many polyurethanes (PUs) are blood-contacting materials due to their good mechanical properties, fatigue resistance, cytocompatibility, biosafety, and relatively good hemocompatibility. Further functionalization of the PUs using chemical synthetic methods is especially attractive for expanding their applications. Herein, a series of catechol functionalized PU (C-PU-PTMEG) elastomers containing variable molecular weight of polytetramethylene ether glycol (PTMEG) soft segment are reported by stepwise polymerization and further introduction of catechol. Tailoring the molecular weight of PTMEG fragment enables a regulable catechol content, mobility of the chain segment, hydrogen bond and microphase separation of the C-PU-PTMEG elastomers, thus offering tunability of mechanical strength (such as breaking strength from 1.3 MPa to 5.7 MPa), adhesion, self-healing efficiency (from 14.9% to 96.7% within 2 hours), anticoagulant, antioxidation, anti-inflammatory properties and cellular growth behavior. As cardiovascular stent coatings, the C-PU-PTMEGs demonstrate enough flexibility to withstand deformation during the balloon dilation procedure. Of special importance is that the C-PU-PTMEG-coated surfaces show the ability to rapidly scavenge free radicals to maintain normal growth of endothelial cells, inhibit smooth muscle cell proliferation, mediate inflammatory response, and reduce thrombus formation. With the universality of surface adhesion and tunable multifunctionality, these novel C-PU-PTMEG elastomers should find potential usage in artificial heart valves and surface engineering of stents.

Design consideration of a novel polymeric transcatheter heart valve through computational modeling

Transcatheter heart valve replacement is becoming a more routine procedure, and this is further supported by positive outcomes from studies involving low-risk patients. Nevertheless, the lack of long-term transcatheter heart valve (TAV) durability is still one of the primary concerns. As a result, more research has been focused on improving durability through various methods such as valve design, computational modeling, and material selection. Recent advancements in polymeric valve fabrication showed that linear low-density polyethylene (LLDPE) could be used as leaflet material for transcatheter heart valves. In this paper, a parametric study of computational simulations showed stress distribution on the leaflets of LLDPE-TAV under diastolic load, and the results were used to improve the stent design. The in silico experiment also tested the effect of shock absorbers in terms of valve durability. The results demonstrated that altering specific stent angles can significantly lower peak stress on the leaflets (13.8 vs. 6.07 MPa). Implementing two layers of shock absorbers further reduces the stress value to 4.28 MPa. The pinwheeling index was assessed, which seems to correlate with peak stress. Overall, the parametric study and the computational method can be used to analyze and improve valve durability.

Evaluating patients’ satisfaction level after using 3D printed PEEK facial implants in repairing maxillofacial deformities

Background

it is generally the case in any traumatic accident where a loss in hard tissue occurs to preform restorative plastic surgery, as there are many materials and approaches used to restore the loss, this research sheds the light on the use of one such material and approach being 3D printed facial implants manufactured from PolyEther Ether Ketone (PEEK) and to evaluate the level of patients’ satisfaction following the use of said method in repairing maxillofacial deformities.

Materials and methods

a research sample consisting of 10 patients with facial deformities underwent maxillofacial reconstructive surgery between 2020 and 2021 in the Department of Oral and Maxillofacial Surgery in the Tishreen University Hospital - Latakia - Syria. All patients underwent Computed Tomography (CT) scans, then the design of the required facial implant was carried out, the final form of the facial implant was printed from PolyEther Ether Ketone (PEEK), and then surgical work was performed, a check-up after 3 months of the surgical procedure was carried out to evaluate the level of satisfaction on a scale of 1–5.

Results

The results from the 10 patients showed a good level of satisfaction except in one case where the facial implant had to be removed due to recurrent infection where the patient showed no signs of response to medicinal treatment following the surgery.

Conclusions

this research suggests that the use of 3D printed PEEK facial implants to be very agreeable in terms of functionality and aesthetics in treating various facial deformities.

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3D Printed PEEK PSIs implants are used for repairing facial injuries.

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PEEK implants are very good means to achieve acceptable aesthetic results.

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The use of the method is very convenient and saves time and effort.

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After surgery results were mostly pleasing.

Visions of TAVR Future: Development and Optimization of a Second Generation Novel Polymeric TAVR

Tissue-based transcatheter aortic valve (AV) replacement (TAVR) devices have been a breakthrough approach for treating aortic valve stenosis. However, with the expansion of TAVR to younger and lower risk patients, issues of long-term durability and thrombosis persist. Recent advances in polymeric valve technology facilitate designing more durable valves with minimal in vivo adverse reactions. We introduce our second-generation polymeric transcatheter aortic valve (TAV) device, designed and optimized to address these issues. We present the optimization process of the device, wherein each aspect of device deployment and functionality was optimized for performance, including unique considerations of polymeric technologies for reducing the volume of the polymer material for lower crimped delivery profiles. The stent frame was optimized to generate larger radial forces with lower material volumes, securing robust deployment and anchoring. The leaflet shape, combined with varying leaflets thickness, was optimized for reducing the flexural cyclic stresses and the valve's hydrodynamics. Our first-generation polymeric device already demonstrated that its hydrodynamic performance meets and exceeds tissue devices for both ISO standard and patient-specific in vitro scenarios. The valve already reached 900 × 106 cycles of accelerated durability testing, equivalent to over 20 years in a patient. The optimization framework and technology led to the second generation of polymeric TAV design- currently undergoing in vitro hydrodynamic testing and following in vivo animal trials. As TAVR use is rapidly expanding, our rigorous bio-engineering optimization methodology and advanced polymer technology serve to establish polymeric TAV technology as a viable alternative to the challenges facing existing tissue-based TAV technology.

Engineering Efforts to Refine Compatibility and Duration of Aortic Valve Replacements: An Overview of Previous Expectations and New Promises

The absence of pharmacological treatments to reduce or retard the progression of cardiac valve diseases makes replacement with artificial prostheses (mechanical or bio-prosthetic) essential. Given the increasing incidence of cardiac valve pathologies, there is always a more stringent need for valve replacements that offer enhanced performance and durability. Unfortunately, surgical valve replacement with mechanical or biological substitutes still leads to disadvantages over time. In fact, mechanical valves require a lifetime anticoagulation therapy that leads to a rise in thromboembolic complications, while biological valves are still manufactured with non-living tissue, consisting of aldehyde-treated xenograft material (e.g., bovine pericardium) whose integration into the host fails in the mid- to long-term due to unresolved issues regarding immune-compatibility. While various solutions to these shortcomings are currently under scrutiny, the possibility to implant fully biologically compatible valve replacements remains elusive, at least for large-scale deployment. In this regard, the failure in translation of most of the designed tissue engineered heart valves (TEHVs) to a viable clinical solution has played a major role. In this review, we present a comprehensive overview of the TEHVs developed until now, and critically analyze their strengths and limitations emerging from basic research and clinical trials. Starting from these aspects, we will also discuss strategies currently under investigation to produce valve replacements endowed with a true ability to self-repair, remodel and regenerate. We will discuss these new developments not only considering the scientific/technical framework inherent to the design of novel valve prostheses, but also economical and regulatory aspects, which may be crucial for the success of these novel designs.

The Technological Basis of a Balloon-Expandable TAVR System: Non-occlusive Deployment, Anchorage in the Absence of Calcification and Polymer Leaflets

Leaflet durability and costs restrict contemporary trans-catheter aortic valve replacement (TAVR) largely to elderly patients in affluent countries. TAVR that are easily deployable, avoid secondary procedures and are also suitable for younger patients and non-calcific aortic regurgitation (AR) would significantly expand their global reach. Recognizing the reduced need for post-implantation pacemakers in balloon-expandable (BE) TAVR and the recent advances with potentially superior leaflet materials, a trans-catheter BE-system was developed that allows tactile, non-occlusive deployment without rapid pacing, direct attachment of both bioprosthetic and polymer leaflets onto a shape-stabilized scallop and anchorage achieved by plastic deformation even in the absence of calcification. Three sizes were developed from nickel-cobalt-chromium MP35N alloy tubes: Small/23 mm, Medium/26 mm and Large/29 mm. Crimp-diameters of valves with both bioprosthetic (sandwich-crosslinked decellularized pericardium) and polymer leaflets (triblock polyurethane combining siloxane and carbonate segments) match those of modern clinically used BE TAVR. Balloon expansion favors the wing-structures of the stent thereby creating supra-annular anchors whose diameter exceeds the outer diameter at the waist level by a quarter. In the pulse duplicator, polymer and bioprosthetic TAVR showed equivalent fluid dynamics with excellent EOA, pressure gradients and regurgitation volumes. Post-deployment fatigue resistance surpassed ISO requirements. The radial force of the helical deployment balloon at different filling pressures resulted in a fully developed anchorage profile of the valves from two thirds of their maximum deployment diameter onwards. By combining a unique balloon-expandable TAVR system that also caters for non-calcific AR with polymer leaflets, a powerful, potentially disruptive technology for heart valve disease has been incorporated into a TAVR that addresses global needs. While fulfilling key prerequisites for expanding the scope of TAVR to the vast number of patients of low- to middle income countries living with rheumatic heart disease the system may eventually also bring hope to patients of high-income countries presently excluded from TAVR for being too young.

Anisotropic elastic behavior of a hydrogel-coated electrospun polyurethane: Suitability for heart valve leaflets

Although xenograft biomaterials have been used for decades in replacement heart valves, they continue to face multiple limitations, including limited durability, mineralization, and restricted design space due to their biological origins. These issues necessitate the need for novel replacement heart valve biomaterials that are durable, non-thrombogenic, and compatible with transcatheter aortic valve replacement devices. In this study, we explored the suitability of an electrospun poly(carbonate urethane) (ES-PCU) mesh coated with a poly(ethylene glycol) diacrylate (PEGDA) hydrogel as a synthetic biomaterial for replacement heart valve leaflets. In this material design, the mesh provides the mechanical support, while the hydrogel provides the required surface hemocompatibility. We conducted a comprehensive study to characterize the structural and mechanical properties of the uncoated mesh as well as the hydrogel-coated mesh (composite biomaterial) over the estimated operational range. We found that the composite biomaterial was functionally robust with reproducible stress-strain behavior within and beyond the functional ranges for replacement heart valves, and was able to withstand the rigors of mechanical evaluation without any observable damage. In addition, the composite biomaterial displayed a wide range of mechanical anisotropic responses, which were governed by fiber orientation of the mesh, which in turn, was controlled with the fabrication process. Finally, we developed a novel constitutive modeling approach to predict the mechanical behavior of the composite biomaterial under in-plane extension and shear deformation modes. This model identified the existence of fiber-fiber mechanical interactions in the mesh that have not previously been reported. Interestingly, there was no evidence of fiber-hydrogel mechanical interactions. This important finding suggests that the hydrogel coating can be optimized for hemocompatibility independent of the structural mechanical responses required by the leaflet. This initial study indicated that the composite biomaterial has mechanical properties well-suited for replacement heart valve applications and that the electrospun mesh microarchitecture and hydrogel biological properties can be optimized independently. It also reveals that the structural mechanisms contributing to the mechanical response are more complicated than what was previously established and paves the pathway for more detailed future studies.

Anti-Biofouling Polymers with Special Surface Wettability for Biomedical Applications

The use of anti-biofouling polymers has widespread potential for counteracting marine, medical, and industrial biofouling. The anti-biofouling action is usually related to the degree of surface wettability. This review is focusing on anti-biofouling polymers with special surface wettability, and it will provide a new perspective to promote the development of anti-biofouling polymers for biomedical applications. Firstly, current anti-biofouling strategies are discussed followed by a comprehensive review of anti-biofouling polymers with specific types of surface wettability, including superhydrophilicity, hydrophilicity, and hydrophobicity. We then summarize the applications of anti-biofouling polymers with specific surface wettability in typical biomedical fields both in vivo and in vitro, such as cardiology, ophthalmology, and nephrology. Finally, the challenges and directions of the development of anti-biofouling polymers with special surface wettability are discussed. It is helpful for future researchers to choose suitable anti-biofouling polymers with special surface wettability for specific biomedical applications.

A hydrophobic antifouling surface coating on bioprosthetic heart valves for enhanced antithrombogenicity

Thrombosis is an important factor that causes the failure of artificial biological valves in addition to calcification and immune rejection. A hydrophobic antifouling surface can improve blood compatibility by reducing the absorption of protein. In this study, porcine pericardium was cross-linked with glycidyl methacrylate, and carbon-carbon double bonds were introduced. Then, fluoride monomer was added so that the pericardial surface would become hydrophobic and antifouling. Fluoride modification changed the hydrophilicity of the pericardium surface, and the surface water contact angle increased from 84° to 143°. Compared with unmodified pericardium, the adsorption of bovine serum albumin and fibrinogen decreased by 93.1% and 85%, respectively, and the anti-thrombogenicity was greatly enhanced.

Long-Term Stability and Biocompatibility of Pericardial Bioprosthetic Heart Valves

The use of bioprostheses for heart valve therapy has gradually evolved over several decades and both surgical and transcatheter devices are now highly successful. The rapid expansion of the transcatheter concept has clearly placed a significant onus on the need for improved production methods, particularly the pre-treatment of bovine pericardium. Two of the difficulties associated with the biocompatibility of bioprosthetic valves are the possibilities of immune responses and calcification, which have led to either catastrophic failure or slow dystrophic changes. These have been addressed by evolutionary trends in cross-linking and decellularization techniques and, over the last two decades, the improvements have resulted in somewhat greater durability. However, as the need to consider the use of bioprosthetic valves in younger patients has become an important clinical and sociological issue, the requirement for even greater longevity and safety is now paramount. This is especially true with respect to potential therapies for young people who are afflicted by rheumatic heart disease, mostly in low- to middle-income countries, for whom no clinically acceptable and cost-effective treatments currently exist. To extend longevity to this new level, it has been necessary to evaluate the mechanisms of pericardium biocompatibility, with special emphasis on the interplay between cross-linking, decellularization and anti-immunogenicity processes. These mechanisms are reviewed in this paper. On the basis of a better understanding of these mechanisms, a few alternative treatment protocols have been developed in the last few years. The most promising protocol here is based on a carefully designed combination of phases of tissue-protective decellularization with a finely-titrated cross-linking sequence. Such refined protocols offer considerable potential in the progress toward superior longevity of pericardial heart valves and introduce a scientific dimension beyond the largely disappointing 'anti-calcification' treatments of past decades.

Ulvan mediated VE cadherin antibody and REDV peptide co-modification to improve endothelialization potential of bioprosthetic heart valves

An aging population and a rapid increase in the incidence of degenerative valve diseases have led to greater use of bioprosthetic heart valves (BHVs). The durability of glutaraldehyde cross-linked bioprostheses currently available for clinical use is poor due to calcification, coagulation, and degradation. Decellularization can partially reduce calcification by removal of xenogenic cells, but can also lead to thrombosis, which can be addressed by further surface modification. The natural sulfated polysaccharide ulvan possesses antithrombotic and anti-inflammatory properties, and can behave as a heparinoid to immobilize proteins through their heparin binding sites. VE-cadherin antibody and the Arg-Glu-Asp-Val (REDV) peptide can facilitate selective endothelial cell attachment, adhesion and proliferation. In this study, we functionalized decellularized porcine pericardium (DPP) with ulvan, REDV, and VE-cadherin antibody (U-R-VE). Ulvan was covalently modified to act as a protective coating and spacer for VE-cadherin antibody, and to immobilize REDV. In in vitro tests, we found that functionalization significantly and selectively promoted adhesion and growth of endothelial cells while reducing platelet adhesion, inflammation, and in vitro calcification of DPPs. In an in vivo subdermal implantation model, U-R-VE modified DPP exhibited greater endothelialization potential and biocompatibility compared with unmodified pericardium. Thus, U-R-VE modification provides a promising solution to the problem of preparing BHVs with enhanced endothelialization potential.

Transcatheter Heart Valves: A Biomaterials Perspective

Heart valve disease is prevalent throughout the world, and the number of heart valve replacements is expected to increase rapidly in the coming years. Transcatheter heart valve replacement (THVR) provides a safe and minimally invasive means for heart valve replacement in high-risk patients. The latest clinical data demonstrates that THVR is a practical solution for low-risk patients. Despite these promising results, there is no long-term (>20 years) durability data on transcatheter heart valves (THVs), raising concerns about material degeneration and long-term performance. This review presents a detailed account of the materials development for THVRs. It provides a brief overview of THVR, the native valve properties, the criteria for an ideal THV, and how these devices are tested. A comprehensive review of materials and their applications in THVR, including how these materials are fabricated, prepared, and assembled into THVs is presented, followed by a discussion of current and future THVR biomaterial trends. The field of THVR is proliferating, and this review serves as a guide for understanding the development of THVs from a materials science and engineering perspective.

Self-healing polyurethane-elastomer with mechanical tunability for multiple biomedical applications in vivo

The unique properties of self-healing materials hold great potential in the field of biomedical engineering. Although previous studies have focused on the design and synthesis of self-healing materials, their application in in vivo settings remains limited. Here, we design a series of biodegradable and biocompatible self-healing elastomers (SHEs) with tunable mechanical properties, and apply them to various disease models in vivo, in order to test their reparative potential in multiple tissues and at physiological conditions. We validate the effectiveness of SHEs as promising therapies for aortic aneurysm, nerve coaptation and bone immobilization in three animal models. The data presented here support the translation potential of SHEs in diverse settings, and pave the way for the development of self-healing materials in clinical contexts.

Increased utilization of bioprosthetic aortic valve technology:Trends, drivers, controversies and future directions

Introduction: Bioprosthetic valves (BPV) implanted surgically or by transcatheter valve implantation (TAVI) comprise an overwhelming majority of substitute aortic valves implanted worldwide.Areas Covered: Prominent drivers of this trend are: 1) BPV patients have generally better outcomes than those with a mechanical valve, and remain largely free of anticoagulation and its consequences; 2) BPV durability has improved over the years; and 3) the expanding use of TAVI and valve-in-valve (VIV) procedures permitting interventional management of structural valve degeneration (SVD). Nevertheless, key controversies exist: 1) optimal anticoagulation regimens for surgical and TAVI BPVs; 2) the incidence, mechanisms and mitigation strategies for SVD; 3) the use of VIV for treatment of SVD, and 4) valve selection recommendations for difficult cohorts, (e.g. patients 50-70 years, patients <50, childbearing age women). This communication reviews trends in and drivers of BPV utilization, current controversies, and future directions affecting BPV use.Expert Opinion: Long-term data are needed in several areas related to aortic BPV use, including anticoagulation/antiplatelet therapy, especially following TAVI. TAVI and especially VIV durability and optimal use warrant will benefit greatly from long-term data. Certain populations may benefit from such high-quality data on multi-year outcomes, particularly younger patients.

Improved in vivo stability of silicon-containing polyurethane by fluorocarbon side chain modulation of the surface structure

As a class of widely used biomedical materials, polyurethanes suffer from their insufficient stability in vivo. Although the commercialized silicone-polyetherurethanes (SiPEUs) have demonstrated excellent biostability compared with polyetherurethanes (PEUs) for long-term implantation, the usage of polydimethylsiloxane (PDMS) inevitably decreased the mechanical properties and unexpected breaches were observed. In this study, we introduced a fluorinated diol (FDO) into SiPEU to modulate the molecular interactions and micro-separated morphology. The fluorinated silicon-containing polyurethane (FSiPEU) was achieved with desirable silicone- and fluorine-enriched surfaces and mechanical properties at a low silicon content. As evidenced by in vitro culture of macrophages and in vivo hematoxylin-eosin (H&E) staining, FSiPEU demonstrated a minimized inflammatory response. After implantation in mice for 6 months, the material was devoid of significant surface degradation and had the least chain cleavage of soft segments. The results indicate that FSiPEU could be promising candidates for long-term implantation considering the combination of biostability, biocompatibility and mechanical performances.

Polyphenols as a versatile component in tissue engineering

The fabrication of functional tissue or organs substitutes has always been the pursuit of goals in the field of tissue engineering. But even biocompatible tissue-engineered scaffolds still suffer from immune rejection, subsequent long-term oxidative stress and inflammation, which can delay normal tissue repair and regeneration. As a well-known natural antioxidant, polyphenols have been widely used in tissue engineering in recent years. The introduced polyphenols not only reduce the damage of oxidative stress to normal tissues, but show specific affinity to functional molecules, such as receptors, enzyme, transcription and transduction factors, etc. Therefore, polyphenols can promote the recovery process of damaged tissues by both regulating tissue microenvironment and participating in cell events, which embody specifically in antioxidant, anti-inflammatory, antibacterial and growth-promoting properties. In addition, based on its hydrophilic and hydrophobic moieties, polyphenols have been widely used to improve the mechanical properties and anti-degradation properties of tissue engineering scaffolds. In this review, the research advances of tissue engineering scaffolds containing polyphenols is discussed systematically from the aspects of action mechanism, introduction method and regulation effect of polyphenols, in order to provide references for the rational design of polyphenol-related functional scaffolds.

Cross-Linking Porcine Pericardium by 3,4-Dihydroxybenzaldehyde: A Novel Method to Improve the Biocompatibility of Bioprosthetic Valve

Heart valve replacement is an effective therapy for patients with moderate to severe valvular stenosis or regurgitation. Most bioprosthetic heart valves applied clinically are based on cross-linking with glutaraldehyde (GLUT), but they have some drawbacks like high cytotoxicity, severe calcification, and poor hemocompatibility. In this study, we focused on enhancing the properties of bioprosthetic heart valves by cross-linking with 3,4-dihydroxybenzaldehyde (DHBA). The experiment results revealed that compared with GLUT cross-linked porcine pericardium (PP), the relative amount of platelets absorbed on the surface of DHBA cross-linked PP decreased from 0.294 ± 0.034 to 0.176 ± 0.028, and the activated partial thromboplastin time (APTT) increased from 9.9 ± 0.1 to 15.2 ± 0.1 s, indicating improved hemocompatibility. Moreover, anticalcification performance and cytocompatibility were greatly enhanced by DHBA cross-linking. In conclusion, the properties of bioprosthetic valves could be effectively improved by processing valves with a DHBA-based cross-linking method.

Fabrication and in-vitro characterization of a polymeric aortic valve for minimally invasive valve replacement

The valve replacement therapy is the standard treatment for severe heart valve diseases. Nowadays, two types of commercial prosthesis are available: mechanical and biological, but both of them have severe limitations. Moreover, alternative therapeutic approach for valve replacement, based on minimally invasive techniques (MIAVR), motivates the search for new valve materials. In this study a polyurethane-based self-expandable tri-leaflets heart valve compatible with MIAVR procedure is proposed. The device is based on the development, fabrication and characterization of three different elements: the leaflets, the polymeric stent for supporting the leaflets, and the external metallic stent for anchoring the valve to the native aortic root. The polymeric stent and the valve leaflets were fabricated using a thermoplastic silicone-polycarbonate-urethane using 3D printing and spray technology while the external metallic stent was made in nickel titanium (Nitinol) to obtain a self-expandable valve after the crimping process. The three elements were assembled in the completed device and tested by crimping, fatigue and fluid-dynamic test. The novel polymeric valve proposed showed promising results about valve crimping capabilities, durability and fluid dynamic performances. This approach could offer advantages such as low cost and to produce a tailor-made device basing on patient's imaging data. Moreover, the selected biomaterial offers the potential to have a device that could need of permanent anticoagulation and lack of calcification.

Extracellular matrix coating improves the biocompatibility of polymeric heart valves

Prosthetic heart valve replacement is an effective therapy for patients with valvular heart disease. New-type polymer materials provide potential choices of material for preparing prosthetic heart valves. In this study, we focused on enhancing the biocompatibility of polystyrene-block-isobutylene-block-styrene (SIBS) by surface modification with an extracellular matrix (ECM). Experimental results demonstrated that the ECM coating increased the adsorption resistance against protein and platelets. SIBS coated with an ECM adsorbed much less bovine serum albumin and fibrinogen (5.38 μg cm-2 and 31.53 μg cm-2, respectively) than the original material (90.84 μg cm-2 and 132.38 μg cm-2, respectively). The relative platelet adsorption of the ECM-modified SIBS was lower than that of SIBS (0.04 versus 0.10). Moreover, the surface coating could also reduce endothelial cytotoxicity, suppress the immune response, and potentially induce tissue regeneration. In conclusion, ECM coating improved the biocompatibility of SIBS effectively.

In Vitro Durability and Stability Testing of a Novel Polymeric Transcatheter Aortic Valve

Transcatheter aortic valve replacement (TAVR) has emerged as an effective therapy for the unmet clinical need of inoperable patients with severe aortic stenosis (AS). Current clinically used tissue TAVR valves suffer from limited durability that hampers TAVR's rapid expansion to younger, lower risk patients. Polymeric TAVR valves optimized for hemodynamic performance, hemocompatibility, extended durability, and resistance to calcific degeneration offer a viable solution to this challenge. We present extensive in vitro durability and stability testing of a novel polymeric TAVR valve (PolyNova valve) using 1) accelerated wear testing (AWT, ISO 5840); 2) calcification susceptibility (in the AWT)-compared with clinically used tissue valves; and 3) extended crimping stability (valves crimped to 16 Fr for 8 days). Hydrodynamic testing was performed every 50M cycles. The valves were also evaluated visually for structural integrity and by scanning electron microscopy for evaluation of surface damage in the micro-scale. Calcium and phosphorus deposition was evaluated using micro-computed tomography (μCT) and inductive coupled plasma spectroscopy. The valves passed 400M cycles in the AWT without failure. The effective orifice area kept stable at 1.8 cm with a desired gradual decrease in transvalvular pressure gradient and regurgitation (10.4 mm Hg and 6.9%, respectively). Calcium and phosphorus deposition was significantly lower in the polymeric valve: down by a factor of 85 and 16, respectively-as compared to a tissue valve. Following the extended crimping testing, no tears nor surface damage were evident. The results of this study demonstrate the potential of a polymeric TAVR valve to be a viable alternative to tissue-based TAVR valves.