Bioprosthetic Valve Size Selection to Optimize Aortic Valve ReplacementSurgical Outcome: A Fluid-Structure Interaction Modeling Study

Aortic valve replacement(AVR)remains a major treatment option for patients with severe aortic valve disease.Clinical outcome of AVR is strongly dependent on implanted prosthetic valve size.Fluid-structure interaction(FSI)aortic root models were constructed to investigate the effect of valve size on hemodynamics of the implanted bioprosthetic valve and optimize the outcome of AVR surgery.FSI models with 4 sizes of bioprosthetic valves(19(No.19),21(No.21),23(No.23)and 25 mm(No.25))were constructed.Left ventricle outflow track flow data from one patient was collected and used as model flow conditions.Anisotropic Mooney–Rivlin models were used to describe mechanical properties of aortic valve leaflets.Blood flow pressure,velocity,systolic valve orifice pressure gradient(SVOPG),systolic cross-valve pressure difference(SCVPD),geometric orifice area,and flow shear stresses from the four valve models were compared.Our results indicated that larger valves led to lower transvalvular pressure gradient,which is linked to better post AVR outcome.Peak SVOPG,mean SCVPD and maximum velocity for Valve No.25 were 48.17%,49.3%,and 44.60%lower than that from Valve No.19,respectively.Geometric orifice area from Valve No.25 was 52.03%higher than that from Valve No.19(1.87 cm2 vs.1.23 cm2).Implantation of larger valves can significantly reduce mean flow shear stress on valve leaflets.Our initial results suggested that larger valve size may lead to improved hemodynamic performance and valve cardiac function post AVR.More patient studies are needed to validate our findings.

Redoing a bioprosthetic tricuspid valve replacement with pacemaker wire through the ruined bioprosthetic valve orifice

Severe tricuspid regurgitation with permanent pacemaker wire passing through the orifice of bioprosthetic tricuspid valve is extremely rare. We present a case of such kind of patient and redid bioprosthetic tricuspid valve replacement. A hawk mouth forceps for bone surgery was used to cut off the mental ring of ruined bioprosthetic tricuspid valve and the ruined valve was removed. A new bioprosthetic tricuspid valve was implanted and the wire of permanent pacemaker was left outside the ring of bioprosthetic tricuspid valve. This method may be helpful for such kind of patient.

Is it the time to reconsider the choice of valves for cardiac surgery： mechanical or bioprosthetic？

Valvular heart disease is a pathologic process involving one or more of the four valves(aortic,pulmonary,mitral and tricuspid)of the heart typified by stenosis or regurgitation and leading to patient symptoms.The most common causes are tissue degeneration,rheumatic fever and congenital heart diseases.Aortic valve replacement(AVR)using either mechanical or bioprosthetic(tissue)valves via open-heart surgical

Comparison of the early curative effect in patients undergoing mechanical vs. bioprosthetic aortic valve replacement with concomitant annuloplasty by the Nicks procedure

Background The probability of prosthesis-patient mismatch(PPM)is high in aortic valve replacement surgery for small aortic valve annulus,which increases the postoperative prosthetic valve transvalvular pressure gradient.Concurrent aortic annuloplasty is a commonly applied surgical procedure,but there is currently no uniform standard or guideline on the type of prosthetic valve that should be used during surgery.Therefore,this study aimed to analyze whether there was any difference in the short-term prognosis between the choice of mechanical valves and bioprosthetic valves during aortic valve replacement surgery with concomitant aortic annuloplasty by the Nicks procedure.Methods A retrospective analysis was conducted based on the clinical data from 55 patients undergoing aortic valve replacement surgery with concomitant annuloplasty by the Nicks procedure at the Cardiac Surgery Department of Guangdong Provincial People’s Hospital from November 2021 to December 2023.In this study,all patients received aortic annuloplasty by the Nicks procedure.Among these patients,30 were in the mechanical valve group,while the other 25 were in the bioprosthetic valve group.Data including left ventricular end-diastolic/endsystolic diameters,left ventricular ejection fraction,interventricular septal thickness,left ventricular posterior wall thickness,transvalvular pressure gradient,left ventricular fractional shortening,and left ventricular mass index were collected 1 week preoperatively and 1 week and 3 months postoperatively.Information on gender,age,body surface area,types of perioperative complications,operation time,complication rates,and outcomes was also collected.Results Among the 55 patients enrolled in this study,4 died.The main causes of death included postoperative low cardiac output syndrome,severe pulmonary infection,and multi-organ dysfunction.Meanwhile,there was a statistically significant difference in left ventricular end-diastolic diameter between the mechanical valve group and the biological valve group 1 week after surgery.However,differences in other indicators such as aortic crossclamp duration,cardiopulmonary bypass duration,postoperative ventilator support duration,postoperative intensive care unit(ICU)stay,total postoperative hospital stay,and echocardiography results 1 week and 3 months postoperatively were not significant between the two groups.Conclusions For patients undergoing aortic annuloplasty by the Nicks procedure in the aortic valve replacement surgery,the postoperative recovery time is not significantly different between the bioprosthetic and mechanical valve groups.Additionally,there is no notable difference in the improvement of left ventricular function or the reduction of PPM incidence between the two types of valves.[S Chin J Cardiol 2024;25(1):29-37].

Recent progress in functional modification and crosslinking of bioprosthetic heart valves

Valvular heart disease(VHD),clinically manifested as stenosis and regurgitation of native heart valve,is one of the most prevalent cardiovascular diseases with high mortality.Heart valve replacement surgery has been recognized as golden standard for the treatment of VHD.Owing to the clinical application of transcatheter heart valve replacement technic and the excellent hemodynamic performance of bioprosthetic heart valves(BHVs),implantation of BHVs has been increasing over recent years and gradually became the preferred choice for the treatment of VHD.However,BHVs might fail within 10-15 years due to structural valvular degeneration(SVD),which was greatly associated with drawbacks of glutaraldehyde crosslinked BHVs,including cytotoxicity,calcification,component degradation,mechanical failure,thrombosis and immune response.To prolong the service life of BHVs,much effort has been devoted to overcoming the drawbacks of BHVs and reducing the risk of SVD.In this review,we summarized and analyzed the research and progress on:(i)modification strategies based on glutaraldehyde crosslinked BHVs and(ii)nonglutaraldehyde crosslinking strategies for BHVs.

A strategy for mechanically integrating robust hydrogeltissue hybrid to promote the anti-calcification and endothelialization of bioprosthetic heart valve

Bioprosthetic heart valve(BHV)replacement has been the predo-minant treatment for severe heart valve diseases over decades.Most clinically available BHVs are crosslinked by glutaraldehyde(GLUT),while the high toxicity of residual GLUT could initiate calcification,severe thrombosis,and delayed endothelializa-tion.Here,we construed a mechanically integrating robust hydrogel-tissue hybrid to improve the performance of BHVs.In particular,recombinant humanized coilagen type Ⅲ(rhCOLⅢ),which was precisely customized with anti-coagulant and pro-endothelialization bioactivity,was first incorporated into the polyvinyl alcohol(PVA)-based hydrogel via hydrogen bond interactions.Then,tannic acid was introduced to enhance the mechanicalperfo of PVA-based hvdrogel and interfacial bonding between the hydrogel layer and bio-derived tissue due to the strong affinity for a wide range of substrates.In vitro and in vivo experimental results confirmed that the GLUT-crosslinked BHVs modified by the robust PVA-based hydrogel embedded rhCOLII and TA possessed long-term anti-coagulant,accelerated endothelialization,mild inflammatory response and anti-calcification properties.Therefore,our mechanically integrating robust hydrogel-tissue hybrid strategy showed the potential to enhance the service function and prolong the service life of the BHVs after implantation.

Reintervention with Transcatheter and Surgical Aortic Valves: A Systematic Review and Meta-Analysis

Background: Despite expanding indications, data regarding the long-term durability of transcatheter heart valves (THV) are limited. Methods: We performed a systematic review and meta-analysis of all published studies with ≥5years of follow-up reporting aortic valve reintervention rates of transcatheter (TAVR) and surgical aortic valve replacement (SAVR). Randomized controlled trials (n = 4) and propensity-matched observational studies (n = 1) involving all surgical risk categories were included. The primary endpoint was the composite of aortic valve reintervention and death. Results: The meta- analysis included 4145 patients: 2101 underwent TAVR (mean age 81.7 ± 6.7 years, 54% male) and 2044 SAVR (mean age 81.8 ± 6.6 years, 54% male). All TAVR procedures were performed with early generations of THV. At a median follow-up of 5 years (range 5 - 6 years), TAVR had higher reintervention rates (odds ratio (OR) 3.33;95% CI: [1.78, 6.24], p < 0.001, I2 = 0%), all-cause mortality (OR 1.45;95% CI: [1.22, 1.75], p < 0.001, I2 = 44%) and the composite of reintervention and death (OR 1.47;95% CI: [1.14, 1.91], p < 0.001, I2 = 64%). Rates of myocardial infarction, transient ischemic attack, stroke, endocarditis, and the composite of endocarditis and thrombosis were similar between the groups. Conclusion: Despite comparable short and medium-term results, TAVR with early-generation THV has higher rates of reintervention and the composite of reintervention and death. Further studies employing newer definitions of structural valve deterioration and bioprosthetic valve failure are needed to assess whether technological enhancements in THV technology will improve long-term outcomes.

Functional non-glutaraldehyde treated porcine pericardium for anti-coagulation,anti-calcification,and endothelial proliferation bioprosthetic heart valves

In the last decade,the number of transcatheter heart valve replacement for severe heart valve disease has increased exponentially.Although the bioprosthetic artificial heart valve(BHV)has similar fluid dynamics performance to the original heart valve compared with mechanical heart valve so that there is no need to take long-term anticoagulant drugs to prevent thromboembolism,transcatheter BHV replacement are still at risk for thrombosis during the first few months according to the clinical data.However,the use of antithrombotic drugs can also increase the risk of bleeding.Therefore,it is particularly important to improve the anticoagulant properties for the BHV itself.In this work,a kind of non-glutaraldehyde cross-linked BHV material with excellent antithrombotic ability has been prepared from carboxylated oxazolidine treated porcine pericardium(consisting of collagen,elastin and glycoprotein)with the further graft of the anticoagulant heparin sodium via hydrophilic modified chitosan.Along with the similar mechanical properties and collagen stability comparable to the glutaraldehyde cross-linked porcine pericardium(PP),these functional non-glutaraldehyde cross-linked PPs exhibit better biocompatibility,promoted endothelial proliferation and superior anti-calcification ability.More importantly,excellent anticoagulant activity can be observed in the hematological experiments in vivo and in vitro.In summary,these excellent performances make these functional non-glutaraldehyde cross-linked PPs great potentialities in the BHV applications.

A NEW TYPE OF BIOPROSTHETIC HEART VALVE

Jin Lei,a professor at Fu Wai Hospital,Chinese Academy of Medical Sciences,invented a new method of chemical

Crosslinking of Bovine Pericardia Using Procyanidins

The aim of this study was to evaluate the crosslinking effect of a naturally crosslinking reagent-procyanidins （PA）-on the materials of bioprosthetic heart valves. After fixing bovine pericardial tissues by procyanidins, crosslikng characteristics, mechanical properties, in vitro enzymatic degradation resistance, the hydrophilicity and hemolysis tests were examined. The results showed that the fixation of biological tissue with glutaraldehyde （GA） or procyanidins increased its denaturation temperature, the surface hydrophilieity and mechanical properties as well as in vitro enzymatic degradation resistance. There were no significant differences in denaturation temperature, mechanical properties, the hydrophilicity and the in vitro enzymatic degradation between the glutaraldehyde and procyanidins fixed tissues. However, the ultimate tensile strength of the procyanidins fixed tissues was significantly superior to the glutaraldehyde fixed tissues. The hemolysis tests showed that hemolysis rate of the proeyanidins fixed tissues was lower than that of the glutaraldehyde fixed tissues. This study shows that procyanidins can crosslink which bovine pericardiaa effectively without toxicity. Our results suggest that this method might be a useful approach for the preparation of bioprosthetic heart valve.

Polyphenol based hybrid nano-aggregates modified collagen fibers of biological valve leaflets to achieve enhanced mechanical,anticoagulation and anti-calcification properties

Glutaraldehyde(Glut)-crosslinked porcine pericardium and bovine pericardium are mainly consisted of collagen and widely used for the preparation of heterogenous bioprosthetic heart valves(BHV),which play an important role in the replacement therapy of severe valvular heart disease,while their durability is limited by degeneration due to calcification,thrombus,endothelialization difficulty and prosthetic valve endocarditis.Herein,we develop a novel BHV,namely,TPly-BP,based on natural tannic acid and polylysine to improve the durability of Glut crosslinked bovine pericardium(Glut-BP).Impressively,tannic acid and polylysine could form nanoaggregates via multiple hydrogen bonds and covalent bonds,and the introduction of nanoaggregates not only improved the mechanical properties and collagen stability but also endowed TPIy-BP with good biocompatibility and hemocompatibility.Compared to Glut-BP,TPIy-BP showed significantly reduced cytotoxicity,improved endothelial cell adhesion,a low hemolysis ratio and obviously reduced platelet adhesion.Importantly,TPly-BP exhibited great antibacterial and in vivo anti-calcification ability,which was expected to improve the in vivo durability of BHVs.These results suggested that TPly-BP would be a potential candidate for BHV.

Polyphenol based hybrid nano-aggregates modified collagen fibers of biological valve leaflets to achieve enhanced mechanical,anticoagulation and anti-calcification properties

Glutaraldehyde(Glut)-crosslinked porcine pericardium and bovine pericardium are mainly consisted of collagen and widely used for the preparation of heterogenous bioprosthetic heart valves(BHV),which play an important role in the replacement therapy of severe valvular heart disease,while their durability is limited by degeneration due to calcification,thrombus,endothelialization difficulty and prosthetic valve endocarditis.Herein,we develop a novel BHV,namely,TPly-BP,based on natural tannic acid and polylysine to improve the durability of Glut crosslinked bovine pericardium(Glut-BP).Impressively,tannic acid and polylysine could form nanoaggregates via multiple hydrogen bonds and covalent bonds,and the introduction of nanoaggregates not only improved the mechanical properties and collagen stability but also endowed TPly-BP with good biocompatibility and hemocompatibility.Compared to Glut-BP,TPly-BP showed significantly reduced cytotoxicity,improved endothelial cell adhesion,a low hemolysis ratio and obviously reduced platelet adhesion.Importantly,TPly-BP exhibited great antibacterial and in vivo anti-calcification ability,which was expected to improve the in vivo durability of BHVs.These results suggested that TPly-BP would be a potential candidate for BHV.