Imaging of pannus formation in patients with mechanical heart valves

Patient-prosthesis mismatch(PPM) should be recognized in patients with elevated transprosthetic gradients but without leaflet immobility, since the treatment strategy may differ in either etiology. However, thrombus and/or pannus formation should be excluded before a diagnosis of PPM is made. Particularly, pannus formation may not be diagnosed with 2-dimensional transesophageal echocardiography. Electrocardiographically gated 64-section multidetector computed tomography(MDCT) may be a promising tool in diagnosing or excluding pannus formation. Our report underlines the utility of MDCT in this regard and also emphasizes the importance of recognition of PPM as a differential diagnosis in such patients.

Univariate Risk Factors for Prolonged Mechanical Ventilation in Patients Undergoing Prosthetic Heart Valves Replacement Surgery

Data from 736 patients undergoing prosthetic heart valve replacement surgery and concomitant surgery （combined surgery） from January 1998 to January 2004 at Union Hospital were retrospectively reviewed. Univariate logistic regression analyses were conducted to identity risk factors for prolonged mechanical ventilation. The results showed that prolonged cardiopulmonary bypass duration, prolonged aortic cross clamp time and low ejection fraction less than 50 percent （50 %） were found to be independent predictors for prolonged mechanical ventilation. Meanwhile age, weight, and preoperative hospital stay （days） were not found to be associated with prolonged mechanical ventilation. It was concluded that. for age and weight, this might be due to the lower number of old age patients （70 years and above） included in our study and genetic body structure of majority Chinese population that favor them to be in normal weight, respectively.

VALVE REPLACEMENT WITH BILEAFLET HEART VALVE PROSTHESIS: FOLLOW-UP OF 170 CASES

From Feb. 1989 to May 1996, 170 patients underwent valve replacement with bileaflet heart valve prosthesis. There were 13 early deaths (mortality of 7-65% ), and 6 late deaths. The Preoperative cardiac function (NYHA) was grade Ⅱ in 96 cases, Ⅳ in 35 cases and Ⅲ to Ⅳ in 77. 1%.Follow-up of the survivors from 3 to 87 (average 39) months showed that most of them could do light and moderate physical labor, and cardiac function was restored to grade Ⅰ～ Ⅱ in 96. 4%. Anti-coagulating bleeding is a common complicaion. However, severe embolism and valve dysfunction had not been found- The authors analysed the causes of death and follow-up data, then emphasized that it was necessary that valve replacement be performed as early as possible, and bileaflet heart valve substitute was the best choice. Furthermore, therapy of little dose anti-coagulating drug(warfarin 1.5～3- 0mg/d) is safe and dependable to most of the patients.

Low-intensity anticoagulation therapy in the pregnant women with mechanical heart valves:a report with 56 cases

Objective To evaluate the method of low-intensity anticoagulation therapy in the pregnant women who had received mechanical heart valve replacemant,and the effects of warfarin on the pregnant women and their fetus. Methods This retrospective study involved 56 pregnant women (61 pregnancies) who had received mechanical heart valve replacement. Their pregnant status,delivery, and anticoagulation therapy were observed

A comprehensive review of cavitation in valves:mechanical heart valves and control valves

Valves are widely used in various working conditions for their flow control functions,and the cavitation inside valves has been investigated owing to its harm to the valve itself and the connecting downstream parts.This paper presents a comprehensive review of the progress that has been achieved in the past years about cavitation in valves including both mechanical heart valves and control valves.The review is divided in the following parts,namely the location where there is a high possibility of the occurrence of cavitation,the parameters that affect cavitation intensity,and the methods to minimize cavitation intensity.It should be noticed that although simulation has been widely used,advanced experiments are still needed in order to obtain accurate analysis of cavitation in valves and the cavitation model still needs to be improved.

Management dilemmas in patients with mechanical heart valves and warfarin-induced major bleeding

Management of warfarin-induced major bleeding in patients with mechanical heart valves is challenging. There is vast controversy and confusion in the type of treatment required to reverse anticoagulation and stop bleeding as well as the ideal time to restart warfarin therapy safely without recurrence of bleeding and/or thromboembolism. Presently, the treatments available to reverse warfarin-induced bleeding are vitamin K, fresh frozen plasma, prothrombin complex concentrates and recombinant activated factor VIIa. Currently, vitamin K and fresh frozen plasma are the recommended treatments in patients with mechanical heart valves and warfarin-induced major bleeding. The safe use of prothrombin complex concentrates and recombinant activated factor VIIa in patients with mechanical heart valves is controversial and needs well-designed clinical studies. With regard to restarting anticoagulation in patients with warfarin-induced major bleeding and mechanical heart valves, the safe period varies from 7-14 d after the onset of bleeding for patients with intracranial bleed and 48-72 h for patients with extra-cranial bleed. In this review article, we present relevant literature about these controversies and suggest recommendations for management of patients with warfarin-induced bleeding and a mechanical heart valve. Furthermore, there is an urgent need for separate specific guidelines from major associations/ professional societies with regard to mechanical heart valves and warfarin-induced bleeding.

Pathogenic Mineralization of Calcium Phosphate on Human Heart Valves

When calcium phosphate forms in soft tissues such as blood vessels and heart valves, it causes disease. The abnormal formation of calcium phosphate is called pathogenic mineralization or pathogenic calcification. Cases of rheumatic heart disease （RHD） always occur with fibrotic and calcified tissue of heart valve. In this article, samples taken from calcified human heart wdves were studied. The characterization was performend by scanning electronic microscope, X-ray Diffraction and transmission electron microscopy with selective diffraction patterns. It is found for the first time that calcium phosphate grains existing in the calcified human heart valves contain octacalcium phosphate （ OCP ）.

Self-Care Practice of Patients with Mechanical Heart Valve Prosthesis Accompanied in Nursing Consultation

The objective was to evaluate the practice of self-care of patients with mechanical heart valve prosthesis. A descriptive, cross-sectional study developed in two outpatient valvopathies of teaching hospitals of Fortaleza/CE, from October 2013 to January 2014. The sample consisted of 127 patients with mechanical heart valve prosthesis. It was held an interview using instrument based on the Theory of Orem’s Self-Care and Brazilian Guidelines for Valvular Heart Diseases. The data were presented in tables and charts. Results: Universal self-care practices of larger adhesion: body hygiene (97.6% washed-haired, daily-bath 92.1%);oral hygiene (brushing teeth before sleeping, 87.4%);fluid intake (drinking-water 95.2%);food intake (salt intake ≤ 2 g/day, 92.1%, fruit and vegetable consumption 79.5%);intestinal eliminations (without blood or mucus—96%, non-parasitic 94.4%);urinary elimination (no blood nor pus-96.8%, urination 4 to 6 times a day, 96%). As self-care developmental requirements predominated: never used illegal drugs, tobacco, alcohol, or stopped at the discovery of the disease (70%). As self-care health deviation requirements we have: making use of certain medication at the right dose (95.2%);attending medical appointments (cardiologist—92.1%;nursing—84.2%);INR control (identifies signs of bleeding— 85.8%). We conclude that patients did not perform all recommended self-care practices, being necessary to establish strategies to reduce the self-care deficit.

In vitro calcification studies on bioprosthetic and decellularized heart valves under quasi-physiological flow conditions

The lifespan of biological heart valve prostheses available in the market is limited due to structural alterations caused by calcium phosphate deposits formed from blood plasma in contact with the tissues.The objective of this work is to present a comparative methodology for the investigation of the formation of calcium phosphate deposits on bioprosthetic and tissue-engineered scaffolds in vitro and the influence of mechanical forces on tissue mineralization.Based on earlier investigations on biological mineralization at constant supersaturation,a circulatory loop simulating dynamic blood flow and physiological pressure conditions was developed.The system was appropriately adapted to evaluate the calcification potential of decellularized(DCV)and glutaraldehyde-fixed(GAV)porcine aortic valves.Results indicated that DCV calcified at higher,statistically nonsignificant,rates in comparison with GAV.This difference was attributed to the tissue surface modifications and cell debris leftovers from the decellularization process.Morphological analysis of the solids deposited after 20 h by scanning electron microscopy in combination with chemical microanalysis electron-dispersive spectroscopy identified the solid formed as octacalcium phosphate(Ca8(PO4)6H2·5H2O,OCP).OCP crystallites were preferentially deposited in high mechanical stress areas of the test tissues.Moreover,GAV tissues developed a significant transvalvular pressure gradient increase past 36 h with a calcium deposition distribution similar to the one found in explanted prostheses.In conclusion,the presented in vitro circulatory model serves as a valuable prescreening methodology for the investigation of the calcification process of bioprosthetic and tissue-engineered valves under physiological mechanical load.

Expression of matrix metalloproteinase-9 was effected by epoxy chloropropan on creating tissue engineered heart valves

Objectives To investigate the effects of epoxy chloropropan on the expression of matrix metalloproteinases-9 （MMP-9）in creating tissue engineered heart valves（TEHV）,on the tissue structures of TEHV,and to study the effects of epoxy chloropropan on the calcification of TEHV.Methods The porcine aortic valve leaflets were digested and decellularized by using detergent and trypsin.Those treated with 0.3% glutaraldehyde for 48 hours were the control group;those treated with 3% epoxy choloropropan for 24 hours were the experimental group.The cultured human bone marrow mesenchymal stem cells（hBMSCs）were seeded onto the decellularized scaffolds of TEHV.The histological studies were done with pathological sections and scanning electron microscopy and reverse transcriptase-polymerase chain reaction（RT-PCR）were used to detect the expression of MMP-9.Results In the experimental group.the histology showed that the BMSCs grew well into the pores and formed a confluent layer in decellularized scaffolds;RT-PCR indicated significantly attenuated expressions of MMP-9,compared with the control（P〈0.05）.Conclusion The decellularized porcine aortic valves treated with 3% epoxy chloropropan may inhibit the expression of MMP-9;therefore epoxy chloropropan may prevent the calcification of tissue engineered heart valves.

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.

Observations on Cardiac Output in Animal Experiments and Clinical Application of Jiuling Bileaflet Mechanical Valve Prosthesis

Objective： To observe the cardiac output （CO） in animals and patients undergone valve replacement with Jiuling bileaflet mechanical valve prosthesis. Methods： 1. Animal experiments： 6 sheep that subjected to mitral replacement with a 2 I-ram-valve prosthesis were measured by open cardiac catheterization intraoperatively. Echocardiographic and open cardiac catheterization under dobutamine stress were performed on 2 sheep survival for 30 months post-operation.2. Patient measurements： CO of 14 cases of aortic valve and 10 cases of mitral valve was measured by open cardiac catheterization,and after 12 months,it was measured by echocardiography. Results： 1. Animal experiments： The mean CO of 6 sheep was 2.5 L/min intraoperatively by catheterization, and that of 2 sheep survival for 30 months post-implant was 3.0 L/min by echocardiography and 2.9 L/min by catheterization, respectively. 2. Patient measurements： The mean cardiac index of 4 patients with 21 mm valve replacement was （2.55 ± 0.27） L/min/m^2by catheterization, and was （2.84 ± 0.13） L/min/m^2 by echocardiography after 12 months. Conclusion： This study demonstrates that cardiac function on animals and patients return to normal activity after undergone the valve replacement, and the newly valve prosthesis shows excellent hemodynamic performance.

Left Ventricular Pacing in a Patient with a Mechanical Tricuspid Prosthesis and High Surgical Risk

Transvenous endocardial pacemaker (PM) implantation is contraindicated in patients with a mechanical tricuspid prosthesis. These patients usually undergo epicardial lead implantation. This case shows the implant of left ventricular (LV) pacing lead through the coronary sinus (CS) in a patient with high surgical risk. A 77-year-old woman with slow atrial fibrillation, left anterior hemi-block and right bundle brunch block, who previously underwent surgical replacement of the mitral and tricuspid valves, was admitted for PM implantation. After 1 month, all the electric parameters were stable. To the best of our knowledge, this is the first Italian case reported of LV pacing in a patient with a mechanical tricuspid prosthesis. The use of LV pacing leads implanted through the CS provides a minimal invasive, safe and effective strategy of pacing in patients with a mechanical tricuspid prosthesis.

Risk Factors for Starr-Edwards Prosthetic Valve Dysfunction: New Insights into an Old Prosthesis

Background: Starr-Edwards prosthetic valves were used for valve replacement, but due to their high thrombogenic risk, they were withdrawn from market. Nevertheless, there are some cases of Starr-Edwards prosthetic valve carriers that have shown long-term survival reaching up to 50 years. The objective of this study was to determine survival in 12 patients with mechanical Starr-Edwards?prosthetic valve and risk factors for predicting valve dysfunction. Methods: Cross-sectional study of patients who had valve replacement with a Starr-Edwards prosthetic valve in a single center from 1968 to 1990. Socio-demographic data, valvular dysfunction variables and mortality were recorded. Logistic regression models to determine valvular dysfunction were constructed. Survival was analyzed with Cox regression and Kaplan-Meier survival curves. Results: A total of 12 patients were analyzed. The median age was 59 years (48.5 - 64). Eleven patients had normal right and left ventricular function. The most common cause of valve replacement was rheumatic valve disease (75%) and it was more frequently in mitral position (50%). Valvular dysfunction was detected in 3 patients (25%). Atrial fibrillation had the highest association with valvular dysfunction (P = 0.005). Stroke was seen in 25% of the population and the overall mortality was 33.3%. Conclusions: The survival of patients with Starr-Edwards prosthetic valve was 66.66% in the 50-year follow-up. Atrial fibrillation had the highest association with prosthetic valvular dysfunction.

Bioinspired polymeric heart valves derived from polyurethane and natural cellulose fibers

In this work,bioinspired anisotropic polymeric heart valves were fabricated using composite materials from polyurethane(PU)and natural cellulose fiber bundles.Cellulose fibers with good alignment were obtained from balsa wood by a top-down process,which were then distributed in polyurethane to pre-pare cellulose fiber bundles reinforced polyurethane(CPU)by hot pressing.The storage modulus of the CPU along the direction parallel to the fiber alignment was 16.70±0.80 MPa,whereas that along the direction perpendicular to the fiber alignment was 8.41±0.94 MPa by dynamic mechanical analysis(DMA)tests at 1 Hz,comparable to aortic valve leaflets.Moreover,2-methacryloyloxyethyl phosphoryl-choline(MPC)was grafted onto the CPU surface(CPU-MPC)to improve hemocompatibility.With MPC modification,the water contact angle decreased significantly from 54.58°±2.98°to 26.42°±3.50°,and the platelet adhesion was reduced by 92%,compared to the original CPU.In vitro cell culture proved that both CPU and CPU-MPC samples did not show any cytotoxicity.Furthermore,the CPU composites were used to fabricate polymeric heart valves,which showed excellent hydrodynamic performance with a large orifice area(1.70 cm 2)and low regurgitation fraction(0.7%),meeting the requirements of ISO 5840-2 standard.

The Application Effect of Predictive Nursing on Cardiopulmonary Rehabilitation of Patients Undergoing Heart Valve Surgery with Extracorporeal Circulation

Objective:To evaluate the application effect of predictive nursing on patients undergoing heart valve surgery with extracorporeal circulation(ECC).Methods:92 ECC patients admitted to the hospital between July 2021 and July 2023 were selected and grouped by random number table method;the observation group practiced predictive nursing,while the reference group practiced conventional nursing.The cardiopulmonary rehabilitation and other indexes were compared between the groups.Results:The postoperative rehabilitation time of the observation group was shorter than that of the reference group,the treatment compliance was higher than that of the reference group,the cardiopulmonary function indexes were all better than that of the reference group,and the complication rate was lower than that of the reference group(P<0.05).Conclusion:The implementation of predictive nursing for ECC patients can promote postoperative rehabilitation,improve patients’treatment compliance,and enhance the cardiopulmonary rehabilitation effect,and nursing safety is high.

Low standard oral anticoagulation therapy for Chinese patients with St.Jude mechanical heart valves

Objective To study the efficacy of the low standard oral anticoagulation therapy following St Jude Medical (SJM) valve implantation for Chinese patients.Methods Totally 805 patients with a mean age of 42.70±11.09 years,enrolled into this study. Among them,230 underwent aortic valve replacements (AVR),381 mitral valve replacements (MVR),189 double valve replacements (DVR) and 5 tricuspid valve replacememts (TVR). All patients received postoperative oral anticoagulation therapy based on a low standard of international normalized ratio (INR,2.0-2.5). Of the 805 patients,710 were followed up for 0.25-13 years (a median,4.15 years). Results Postoperatively,17 adverse events occurred. Operative mortality was 2.11%. The most frequent cause of operative mortality was a low cardiac output. During follow-up,there were 47 anticoagulant-induced hemorrhages [1.59%/patient-year (pt-yr)],10 cases of thromboembolism (0.34%/pt-yr),and 3 mechanical valve thromboses (0.19%/pt-yr). There were 44 late deaths and the linearized late mortality rates were 0.51%pt-yr. Estimates of actuarial survival for all patients at 5 and 10 years was 97.45% (0.70%) and 77.96% (17.44%),respectively.Conclusions A low target INR range of 2.0-2.5 is preferable for Chinese patients so as to reduce the severe bleeding complications in those with conventionally higher levels of INR. The long-term results were satisfactory in terms of the numbers of those who suffered thrombosis,embolism and bleeding.

Bio-inspired anisotropic polymeric heart valves exhibiting valve-like mechanical and hemodynamic behavior

Native heart valve leaflets with layered fibrous structures show anisotropic characteristics,allowing them to withstand complex mechanical loading for long-term cardiac cycles.Herein,two types of silk fibroin(SF)fiber membranes with anisotropic(ASF)and isotropic(ISF)properties were prepared by electrospinning,and were further combined with poly(ethylene glycol)diacrylate(PEGDA)hydrogels to serve as polymeric heart valve(PHV)substitutes(PEGDA-ASF and PEGDA-ISF).The uniaxial tensile tests showed obvious anisotropy of PEGDA-ASF with elastic moduli of 10.95±1.09 and3.55±0.32 MPa,respectively,along the directions parallel and perpendicular to the fiber alignment,while PEGDA-ISF possessed isotropic property with elastic moduli of 4.54±0.43 MPa.The PHVs from both PEGDA-ASF and PEGDA-ISF presented appropriate hydrodynamic properties from pulse duplicator tests according to the ISO 5840-3 standard.However,finite element analysis(FEA)revealed the anisotropic PEGDA-ASF valve showed a lower maximum principle stress value(2.20 MPa)in commissures during diastole compared with that from the isotropic PEGDA-ISF valve(2.37 MPa).In the fully open state,the bending area of the PEGDA-ASF valve appeared in the belly portion and near the attachment line like native valves,however,which was close to free edges for the PEGDA-ISF valve.The Gauss curvature analysis also indicated that the anisotropic PEGDA-ASF valve can produce appropriate surface morphology by dynamically adjusting the movement of bending area during the opening process.Hence,anisotropy of PHVs with bio-inspired layered fibrous struc-tures played important roles in mechanical and hydrodynamic behavior mimicking native heart valves.

Immunological and functional features of decellularized xenogeneic heart valves after transplantation into GGTA1-KO pigs

Decellularization of xenogeneic heart valves might lead to excellent regenerative implants,from which many patients could benefit.However,this material carries various xenogeneic epitopes and thus bears a considerable inherent immunological risk.Here,we investigated the regenerative and immunogenic potential of xenogeneic decellularized heart valve implants using pigs deficient for the galactosyltransferase gene(GGTA1-KO)as novel large animal model.Decellularized aortic and pulmonary heart valves obtained from sheep,wild-type pigs or GGTA1-KO pigs were implanted into GGTA1-KO pigs for 3,or 6 months,respectively.Explants were analyzed histologically,immunhistologically(CD3,CD21 and CD172a)and anti-aGal antibody serum titers were determined by ELISA.Xenogeneic sheep derived implants exhibited a strong immune reaction upon implantation into GGTA1-KO pigs,characterized by massive inflammatory cells infiltrates,presence of foreign body giant cells,a dramatic increase of anti-aGal antibody titers and ultimately destruction of the graft,whereas wild-type porcine grafts induced only a mild reaction in GGTA1-KO pigs.Allogeneic implants,wild-type/wild-type and GGTA1-KO/GGTA1-KO valves did not induce a measurable immune reaction.Thus,GGTA1-KO pigs developed a‘human-like’immune response toward decellularized xenogeneic implants showing that immunogenicity of xenogeneic implants is not sufficiently reduced by decellularization,which detracts from their regenerative potential.

Mechanical versus biological prosthetic heart valves in pregnant women with valvular heart disease

Background The pregnant women with a prosthetic heart valve(PHV)are considered to have a higher risk of cardiovascular,obstetric and fetal/neonatal complications when they underwent anticoagulation therapy in all 3 trimesters.This report evaluated the comparative results of pregnant women wearing mechanical and biological PHV.Methods The outcomes of different types of PHV were assessed retrospectively in pregnant women in Guangdong Provincial People’s Hospital from January 2008 to May 2021.A total of 243 women(319 pregnancies)were enrolled and divided into mechanical PHV group and biological PHV group according to the types of PHV implanted.The baseline data of all pregnancies were studied.Cardiovascular,obstetric and fetal/neonatal complications in 201 completed pregnancies of 165 women with different PHV were analyzed.Results 319 pregnancies occurred,of which 201 pregnancies(165 women)≥20 weeks duration,including 159 pregnancies with mechanical PHV and 42 pregnancies with biological PHV.Miscarriages were more common in women with mechanical PHV[40 pregnancies(14.65%),≤20 weeks],while only one case was noted in women with biological PHV(P<0.05).The induced abortion rate of women with mechanical PHV(27.11%vs.6.52%,P<0.05)was significantly higher compared with that in women with biological PHV.The incidence of cardiovascular,obstetric and fetal/neonatal complications was equally frequent in both groups after 20 weeks of gestation.Conclusions Pregnant women with mechanical PHV were more likely to have a complication of miscarriages than those with biological PHV,mainly due to the anticoagulation therapy.On the other hand,more women with mechanical PHV may choose not to become pregnant than women with biological PHV after counseling the risks of pregnancy.There was no significant difference in other aspects of maternal and fetal complications after 20 weeks of gestation.Women who cannot maintain therapeutic anticoagulation and frequent monitoring of mechanical PHV may consider biological PHV.