Objective: To study early results of hand made fresh (autologous/homologous) pericardial valved conduit in achieving right ventricle to pulmonary artery continuity. Method: Between November 2014 and September 2015, 19...Objective: To study early results of hand made fresh (autologous/homologous) pericardial valved conduit in achieving right ventricle to pulmonary artery continuity. Method: Between November 2014 and September 2015, 19 cases, with diagnosis of Tetralogy of Fallot with Pulmonary stenosis (PS) or Pulmonary atresia (PA) underwent intracardiac repair and Right Ventricular Outflow Tract (RVOT) reconstruction with hand made fresh [autologous (n = 2)/ homologous (n = 17)] pericardial valved conduit. Mean age of the patients at time of surgery was 6.37 years (range 3 months to 18 years), mean weight was 18.52 kilograms (range 6 kg to 40 kg) and mean size of the conduit was 20.7 mm (range 16 mm to 24 mm). Results: All patients had a smooth post-operative course, with mean ICU (Intensive Care Unit) stay of 3.6 days (range 3 days to 6 days) and mean post-operative hospital stay 8.5 days (range 7 days to 16 days). Intra-operative and Post-operative echocardiography revealed moderate Pulmonary regurgitation (PR) in one patient, mild PR in 5 patients and no or trace PR in 13 patients. No patient has developed conduit stenosis or calcification till now. Conclusion: Autologous or homologous pericardial valved conduit provides good early results and is especially suitable for developing world because of zero cost. Long term usefulness of such option remains to be confirmed in terms of dilation, calcification and freedom from intervention.展开更多
Background Percutaneous aortic valve replacement is a promising strategy in the treatment of patients with aortic valve stenosis. And many kinds of valved stents have been implanted in selected patients worldwide. How...Background Percutaneous aortic valve replacement is a promising strategy in the treatment of patients with aortic valve stenosis. And many kinds of valved stents have been implanted in selected patients worldwide. However, the clinical experience is still limited. We developed a W-model valved stent and evaluated the feasibility and safety of percutaneous implantation of the device in the native aortic valve position.Methods A self expanding nitinol stent with W-model, containing porcine pericardium valves in its proximal part, was implanted in six sheep by means of a 14 French catheter through the right common iliac artery under guidance of fluoroscopy. During stent deployment the original aortic valve was pushed against the aortic wall by the self expanding force of the stent while the new valve was expanded. These sheep were followed up shortly after procedure with supra-aortic angiogram and left ventriculography. Additionally, one sheep was sacrificed after the procedure for anatomic evaluation.Results It was possible to replace the aortic valve in the beating heart in four sheep. The procedure failed in two sheep due to coronary orifice occlusion in one case and severe aortic valve regurgitation in the other case. One sheep was killed one hour after percutaneous aortic valve replacement for anatomic evaluation. There were no signs of damage of the aortic JntJma, or of obstruction of the coronary orifice,Conclusions Percutaneous aortic valve replacement with a W-model valved stent in the beating heart is possible. Further studies are mandatory to assess safety and efficacy of this kind of valved stent in larger sample size and by longer follow-up period.展开更多
Background The prognosis of tetralogy of Fallot with absent pulmonary valve (TOF/APV) without operation is poor. We evaluated the surgical outcome of TOF/APV in a single center. Methods Twenty-two TOF/APV patients und...Background The prognosis of tetralogy of Fallot with absent pulmonary valve (TOF/APV) without operation is poor. We evaluated the surgical outcome of TOF/APV in a single center. Methods Twenty-two TOF/APV patients underwent complete surgical correction in our hospital. Right ventricular outflow tract reconstruction was performed using bovine jugular vein (BJV)-valved conduit implantation (n=10), homograft-valved conduit implantation (n=2), or monocusp-valve patch (n=10). Health-related quality of life (QOL) was evaluated during follow-up. Results The overall survival at 5 and 10 years was 86.4±7.3% (confidence interval 69.4–97.2%). The survival rates were significantly different between patients with and without bronchial stenosis (40 and 100%, P=0.0003, log-rank test). The survival of patients aged>6 months was higher than those≤6 months (100 vs. 40%, P=0.0003, log-rank test). Patients with BJV-valved conduits had higher systolic gradients from the right ventricle to the pulmonary artery (RV–PA) compared to those with monocusp-valve patches. BJV-valved conduit implantation was a risk factor for post-operative pulmonary-valve stenosis. The QOL score for patients with BJV-valved conduits was lower than those with monocusp-valve patches (P<0.05). No reoperation was performed during follow-up. Conclusions Bronchial stenosis and lower age (≤6 months) were the main factors influencing post-operative survival. The use of a BJV-valved conduit was a main reason for RV–PA restenosis;thus, the use of a BJV-valved conduit may increase the need for repeat intervention and decrease the post-operative quality of life.展开更多
Background The application of pulmonary valved conduit to reconstruct the continuity between right ventricles and pulmonary artery is one of the major surgeries.This study aimed to establish an in vivo model of in sit...Background The application of pulmonary valved conduit to reconstruct the continuity between right ventricles and pulmonary artery is one of the major surgeries.This study aimed to establish an in vivo model of in situ implantation using pulmonary valved conduit in large animals under off-pump condition to validate the long-term effects of artificial pulmonary valved conduit.Methods Domesticate juvenile male sheep and tissue-engineered poorine pulmonary valved conduit were used for the experiment：30 sheep,weighing （15±3） kg （range 13 to 17 kg） were randomly divided into two groups which were all operated under general anesthesia by off-pump surgery （group 1） and left thoracotomy （group 2）.Two different off-pump surgical methods were used to perform cannulation in sheep pulmonary artery to replace part of sheep pulmonary artery with pulmonary valved conduit which will work together with sheep pulmonary artery and valves.During the experiments,animal survival,complication rates,operating time and blood loss were recorded to compare the results between groups and to establish a surgical method with minimal invasion,simplicity,safety,and high success rates.Results In group 1,a total of 15 cases of surgeries were performed,in which two sheep died; the operative mortality was 13.3％ （2/15）.In group 2,a total of 15 cases of surgeries were performed,and the surgical mortality rate was 0 （0/15）.The operation time and blood loss in group 2 was significantly better than that in group 1.The postoperative echocardiograms showed that,after the surgeries by these two methods,the blood flows were normal,and the valves can open and close freely.Autopsy after 6 months showed that the inner wall and the valves of pulmonary valved conduit were smooth with no thrombus formation.Conclusion These two off-pump methods are feasible and safe with fewer traumas; but the second method is better and particularly suitable for the establishment of a juvenile animal model.展开更多
High Speed on/off Valve(HSV)is an essential component in Aerospace Digital Hydraulic Systems(ADHS),which impose stringent requirements on the dynamic performance and reliability of HSV due to the extreme application e...High Speed on/off Valve(HSV)is an essential component in Aerospace Digital Hydraulic Systems(ADHS),which impose stringent requirements on the dynamic performance and reliability of HSV due to the extreme application environments.However,the faster dynamic leads to increased impact between the spool and valve body,causing severe vibration and wear,which creates a conflict between rapid dynamic and high reliability.To address this problem,a Pre-Excitation Soft Switching Control(PESSC)with both pre-excitation and reverse deceleration functionalities is proposed.The initial current is optimized through pre-excitation to accelerate the opening time,while the application of reverse voltage hastens the decline of electromagnetic force,thereby reducing the spool velocity.The PESSC simultaneously achieves both faster dynamic performance and smaller impact velocity.Moreover,the optimal deceleration voltage parameters are obtained through multi-objective optimization.Experimental results demonstrate that the optimized PESSC shortens the opening time from 2.22 ms to 1.65 ms,reduces the impact velocity by 58.3%,and lowers wear by 55.4%.These findings underline the huge potential of PESSC in enhancing the dynamic performance and reliability of HSVs,offering promising applications in aerospace.展开更多
Rising temperatures and increased droughts caused by climate change significantly reduce crop yields.Halophytes with different photosynthetic metabolism types have specific mechanisms for resistance to climatic factor...Rising temperatures and increased droughts caused by climate change significantly reduce crop yields.Halophytes with different photosynthetic metabolism types have specific mechanisms for resistance to climatic factors.This study analyzed the morphophysiological,biochemical,and molecular-genetic mechanisms of tolerance and adaptation in halophytes,promising candidates for the restoration of salt affected lands in arid and semi-arid areas.Experiments under drought(D)and elevated temperature(eT),as well as their combined action(eT+D),were performed on Atriplex verrucifera M.Bied.(C_(3)plant)and Climacoptera crassa(M.Bieb.)Botsch.(C_(4)-NAD-ME plant)with different types of photosynthesis.The activity of photosystem I(PSI)and the efficiency of photosystem II(PSII)were measured,along with the expression of genes involved in the light(psaA,psaB,psbA,CAB,Fd1,PGR5,and ndhH)and dark(rbcL,Ppc2,and PPDK)reactions of photosynthesis.The content of key carboxylating enzymes ribulose-1,5-bisphosphate carboxylase/oxygenase(Rubisco)and phosphoenolpyruvate carboxylase(PEPC),as well as the photorespiration enzyme glycine decarboxylase(GDC),were assessed.Plant growth and water-salt balance parameters,and activity of enzymes in the malate dehydrogenase(MDH)system nicotinamide adenine dinucleotide(phosphate)(NAD(P))-MDH and NAD(P)-malic enzyme(ME)were also examined.A multivariate analysis of the experimental results revealed that A.verrucifera and C.crassa were both resistant to the effects of these climatic stressors.The tolerance mechanisms of both species were significantly influenced by a high level of photosynthetic plasticity.Nevertheless,differences were observed in the protective mechanisms underlying tolerance.In the C_(3)species,dissipative processes associated with non-photochemical quenching(NPQ)of PSII and MDH system enzymes(malate valves)were activated,particularly under osmotic stress.The negative effects in the C_(3)plants were caused by the combined action of eT+D,which was compensated by an increased expression of rbcL,psaA,CAB,and especially PGR5,i.e.,genes encoding Rubisco large subunit and PSI components:apoproteins A,chlorophyll a/b-associated protein(CAB)of light-harvesting complex,and proton gradient regulation 5(PGR5)protein of the main pathway of cyclic electron transport(CET)around PSI.In C_(4)species,the protective MDH complex was expressed to a lesser extent,but activation of the C_(4)carbon-concentrating mechanism(CCM)and upregulation of PGR5 expression were observed,particularly under the individual action of the factors.Under the combined stress of eT+D,C.crassa exhibited a synergistic effect,where the increase in NPQ level and NAD-ME activity,as well as decrease in NADP-ME activity was less pronounced compared with the effect of singular factors.Comparative physiological,biochemical,and molecular analyses of how C_(3)and C_(4)species response to individual and combined climatic factors provide new insights into sustainable plant adaptation strategies in the face of global climate change.Considering the high nutritional value of these two fodder species,a technological approach could be developed to improve the productivity of salt affected lands.展开更多
Background Cryopreserved conduit valved homografts （CVH） have been widely used in surgical treatment of cardiac disease. This study aimed to determine the extent of host cell ingrowth and the durability and immunoge...Background Cryopreserved conduit valved homografts （CVH） have been widely used in surgical treatment of cardiac disease. This study aimed to determine the extent of host cell ingrowth and the durability and immunogenicity of CVH,and to compare the performance of CVH stored at 4℃ and CVH cryopreserved in liquid nitrogen at -196℃.Methods Heterotopic transplants of canine CVH stored at 4℃ （n=14） and cryopreserved in liquid nitrogen （n=14） were made onto the abdominal aorta of recipient dogs. Animals were sacrificed at 7 and 15 days and at 1, 3, 6, 9, and 12months after transplantation to excise the implanted CVHs. Tissue DNA extraction and quantitative polymerase chain reaction （PCR） were performed to calculate the ratio of donor cells and host cells in the CVH. The tissue viability of CVH after implantation was analyzed by detecting alkaline fibroblast growth factor 2 （FGF-2） using immunohistochemical staining and by observation under transmission electron microscope and scanning electron microscope.Results All the animals survived and recovered well. There were few repopulating host cells （0.04-0.83%） in the implanted CVH at 7 or 15 days. The ratio of ingrowing host cells into the CVH continued rising after implantation and reached 40%-47% in the 12th month postoperation. Histology, transmission electron microscopy and FGF-2immunohistochemical staining indicated that fibroblasts and the host＇s endothelial cells were the main cellular elements invading the CVH. There were no significant differences in results between CVH stored at 4℃ and CVH cryopreserved in liquid nitrogen.Conclusions Host cells growing into CVH are very important for maintaining the long-term structure and function of the implanted CVH. There is no significant difference between CVH storing at 4℃ or in liquid nitrogen in regard to the ingrowth of host cells or of morphologic features after CVH allografting.展开更多
A high-temperature and high-pressure valve is the key equipment of a wind tunnel system;it controls the generation of high-temperature and high-pressure gas.To reduce the adverse impact of high-temperature and high-pr...A high-temperature and high-pressure valve is the key equipment of a wind tunnel system;it controls the generation of high-temperature and high-pressure gas.To reduce the adverse impact of high-temperature and high-pressure gas on the strength of the valve body,a cooling structure is set on the valve seat.This can significantly reduce the temperature of the valve body and valve seat.The effects of its structure on the cooling characteristics and stress of the valve seat are studied,and six main parameters that can completely describe the geometry of the cooling structure are proposed.The central composite design method is used to select sample points,and the multi-objective genetic algorithm(MOGA)method is used for optimal structural design.A modification method according to the main parameters for the valve seat is proposed.The results show that the cooling structure weakens the pressure-bearing capability of the valve seat.Among the six main parameters of the valve seat,the distance from the end face of the lower hole to the Z-axis and the distance from the axis of the lower hole to the origin of the coordinates have the most obvious effects on the average stress of the valve seat.An optimum design value is proposed.This work can provide a reference for the design of high-temperature and high-pressure valves.展开更多
BACKGROUND The management of severe symptomatic aortic stenosis has been revolutionized by transcatheter aortic valve replacement(TAVR),offering a minimally invasive alternative to surgical aortic valve replacement(SA...BACKGROUND The management of severe symptomatic aortic stenosis has been revolutionized by transcatheter aortic valve replacement(TAVR),offering a minimally invasive alternative to surgical aortic valve replacement(SAVR).However,the compara-tive safety and efficacy of these interventions remain subjects of ongoing investigation.AIM To compare the clinical outcomes and safety of TAVR vs SAVR in patients with severe symptomatic aortic stenosis.METHODS A systematic review and meta-analysis were conducted according to PRISMA guidelines.Randomized controlled trials(RCTs)comparing TAVR and SAVR were identified from databases including PubMed,Scopus,and Web of Science up to May 31,2024.Data were extracted on clinical outcomes,including mortality,procedural compli-cations,and post-procedure adverse events.Risk ratios(RRs)with 95%CIs were calculated using a random-effects model.RESULTS A total of 10 RCTs were included.TAVR demonstrated a significantly lower risk of acute kidney injury(RR:0.33;95%CI:0.25–0.44),major bleeding(RR:0.37;95%CI:0.30–0.46),and new-onset atrial fibrillation(RR:0.44;95%CI:0.34–0.57)compared to SAVR.However,TAVR was associated with higher risks of new permanent pacemaker implantation(RR:3.49;95%CI:2.77–4.39),major vascular complications(RR:2.47;95%CI:1.91–3.21),and paraval-vular leaks(RR:4.15;95%CI:3.14–5.48).Mortality at 30 days was comparable(RR:0.95;95%CI:0.78–1.15),but long-term mortality was slightly higher with TAVR in some analyses(RR:1.23;95%CI:1.01–1.49).Rates of stroke(RR:0.97;95%CI:0.81–1.17)and myocardial infarction(RR:0.91;95%CI:0.67–1.24)were similar between the groups.CONCLUSION TAVR offers a less invasive option with significant benefits in reducing acute kidney injury,major bleeding,and new-onset atrial fibrillation,making it particularly advantageous for high-risk surgical candidates.However,higher risks of permanent pacemaker implantation,vascular complications,and paravalvular leaks highlight the need for individualized patient selection and shared decision-making to optimize outcomes.展开更多
BACKGROUND Valvular heart disease affects more than 100 million people worldwide and is associated with significant morbidity and mortality.The prevalence of at least moderate valvular heart disease is 2.5%across all ...BACKGROUND Valvular heart disease affects more than 100 million people worldwide and is associated with significant morbidity and mortality.The prevalence of at least moderate valvular heart disease is 2.5%across all age groups,but its prevalence increases with age.Mitral regurgitation and aortic stenosis are the most frequent types of valvular heart disease in the community and hospital context,res-pectively.Surgical valve replacement(or mitral valve repair)is the standard of care for treating heart valve disease.However,the replacement of a prosthetic heart valve can lead to complications,either in the peri-procedural phase or in the long-term follow-up period.CASE SUMMARY We present a case of a 71-year-old female patient with a history of mitral valve replacement and warfarin anti-coagulation therapy.She was admitted to the intensive care unit due to spontaneously reperfused ischemic stroke of probable cardioembolic etiology.A dysfunctional mitral prosthesis was identified due to malfunction of one of the fixed discs.Furthermore,a possible microthrombotic lesion was suspected.Therefore,systemic thrombolysis was performed with subsequent normalization of mitral disc opening and closing.CONCLUSION This case underscores the critical importance of a multidisciplinary approach for timely decision-making in critically ill patients with prosthetic valve complications.展开更多
Background There is scarce data about comparisons between geriatric assessment tools in patients with aortic stenosis(AS).We aimed to describe the geriatric profile of patients with AS undergoing transcatheter aortic ...Background There is scarce data about comparisons between geriatric assessment tools in patients with aortic stenosis(AS).We aimed to describe the geriatric profile of patients with AS undergoing transcatheter aortic valve implantation(TAVI)and to analyze the ability of different tools for predicting clinical outcomes in this context.Methods This was a single center retrospective registry including patients with AS undergoing TAVI and surviving to hospital discharge.The primary endpoint was all-cause mortality or need for urgent readmission one year after TAVI.Results A total of 377 patients were included(mean age of 80.4 years).Most patients were independent or mildly dependent,with an optimal cognitive status.The proportion of frailty ranged from 17.6%to 49.8%.A total of 20 patients(5.3%)died and 110/377 patients(29.2%)died or were readmitted during follow up.Overall,most components of the geriatric assessment showed an association with clinical outcomes.Disability for instrumental activities showed a significant association with mortality and a strong association with the rate of mortality or readmission.The association between frailty and clinical outcomes was higher for short physical performance battery(SPPB),essential frailty toolset(EFT)and the frailty index based on comprehensive geriatric assessment(IF-VIG)and lower for Fried criteria and FRAIL scale.Conclusions AS patients from this series presented a good physical performance,optimal cognitive status and a reasonably low prevalence of frailty.The best predictive ability was observed for disability for instrumental activities and frailty as measured by the EFT,SPPB and the IF-VIG.展开更多
Pump valve pipeline vibration brings serious safety hazards to the operation of the equipment,for the pump valve system in the process of variable flow,variable speed,variable openings lead to excessive pipeline vibra...Pump valve pipeline vibration brings serious safety hazards to the operation of the equipment,for the pump valve system in the process of variable flow,variable speed,variable openings lead to excessive pipeline vibration.An active damping device(ADD)is used to the vibration of the pump valve pipeline system to apply the control force,to achieve the active control of the pipeline vibration.A pump-valve pipeline vibration test bench was built to compare the control effect of active damping device on pipeline vibration under different pump valve working conditions,and the results show that applying ADD control could effectively suppress the vibration of the pump valve pipeline and enhance the stability of the equipment during operation.At different pump operating rotation frequencies,the vibration amplitude of the pump valve pipeline in working frequency and its multiple frequencies are also effectively suppressed,with the maximum amplitude reduction of more than 60%.For the valve vibration caused by different operating openings,the vibration of the highest reduction of 68%,and the centrifugal pump drive shaft vi-bration reduced by up to 73%,which provides a new idea for vibration control of pump valve pipeline system.展开更多
Gifford-McMahon-type pulse-tube cryocoolers(GM-PTCs)working at liquid helium temperatures are promising in quantum technology and cryogenic physics for their high reliability and minimal vibration.These features stem ...Gifford-McMahon-type pulse-tube cryocoolers(GM-PTCs)working at liquid helium temperatures are promising in quantum technology and cryogenic physics for their high reliability and minimal vibration.These features stem from the fact that there are no extra moving parts introduced into the system.The rotary valve is a key component in GM-PTCs that transfers the output exergy from the compressor to the cold head.Because a low Carnot efficiency of 1.58%is achieved at liquid helium temperatures,optimizing the rotary valve is crucial for improving the efficiency of GM-PTCs.In this regard,an exergy-loss analysis method is proposed in this paper to quantitatively obtain the leakage loss and viscosity loss of a rotary valve by experimental measurements.The results show that viscosity loss accounts for more than 97.5%of the total exergy loss in the rotary valve,and that it is possible to improve the structure of the rotary valve by expanding the flow area by 1.5 times.To verify the method,the cooling temperature and power of a remote two-stage GM-PTC were monitored,with original or optimized rotary valves installed.The experimental results show that compared to the original rotary valve,the optimized rotary valve can improve the cooling efficiency of a GM-PTC by 16.4%,with a cooling power of 0.78 W at 4.2 K.展开更多
Pediatric heart valve replacement(PHVR)remains a challenging procedure due to the uniqueanatomical and physiological characteristics of children,including growth and development,as well asthe long-term need for durabl...Pediatric heart valve replacement(PHVR)remains a challenging procedure due to the uniqueanatomical and physiological characteristics of children,including growth and development,as well asthe long-term need for durable valve function.This review provides an overview of both surgical andtranscatheter options for aortic,mitral,pulmonary,and tricuspid valve replacements in pediatric patients,highlighting the indications,outcomes,and advancements in technology and technique.Surgical valvereplacement traditionally involves the implantation of biological or mechanical prosthetic valves,withbiologicalvalves beingpreferred in children to reduce the need for lifelong anticoagulation therapy.However,the limitation ofbiological prostheses,nanely their inability to grow with the child,necessitates the frequentneed for reoperations.Recent innovations in valve engineering,such as the development of tissue engineeredand expandable valves,aim to address these issues.Transcatheter valve replacement(TVR)has emergedas a promising alternative,particularly for patients with complex anatomy or those who are high-risk fortraditional surgery.While the use of transcatheter devices in children remains limited due to the smallervascular size and limited long-termn data,several studies have demonstrated the feasibility and safety ofthe procedure in certain patient populations.Despite these advancements,challenges related to valvesize,durability,and the need for individualized treatment planning persist.The future of pediatric heartvalve replacemnent will likely involve a multidisciplinary approach combining surgical,transcatheter,andregenerative medicine strategies,aimed at optimizing outcomes,reducing the need for reinterventions,andimproving long-term quality of life for pediatric patients with valvularheart disease.This article discussesall options availab le for patients with valvular dysfunction,making it easy for parents/patients to go to as areference source of information.展开更多
Valvular Heart Disease(VHD),including stenosis and regurgitation,is a significant contributor to global cardiovascular morbidity.Current prosthetic solutions mechanical and bioprosthetic heart valves each present majo...Valvular Heart Disease(VHD),including stenosis and regurgitation,is a significant contributor to global cardiovascular morbidity.Current prosthetic solutions mechanical and bioprosthetic heart valves each present major limitation.Mechanical valves require lifelong anticoagulation due to thrombogenicity,while bioprosthetic valves suffer from structural degeneration and limited durability.Polymeric Heart Valves(PHVs)have emerged as promising alternatives,aiming to integrate the mechanical resilience of synthetic materials with the biocompatibility and hemodynamic performance of natural valves.Recent studies have explored advanced polymers such as Polyhedral Oligomeric Silsesquioxane–Polycarbonate–Urea–Urethane(POSS-PCU),Silicone–Polyurethane Urea(SiPUU),and nanocomposites like Polyvinyl Alcohol(PVA)and SIBS for their enhanced thromboresistance,calcification resistance,and long-term mechanical durability.Complementary to material innovation,fabrication methods such as 3D printing,Melt Electrospinning Writing(MEW),and Focused Rotary Jet Spinning(FRJS)offer patient-specific designs and microstructural control.This review systematically compares traditional and next-generation prostheses,examines mechanical and biological performance,and discusses critical design challenges including porosity,thrombogenicity,and leaflet calcification.Finite Element Analysis(FEA)and Computational Fluid Dynamics(CFD)are highlighted for optimizing design and simulating physiological conditions.By presenting recent preclinical progress and manufacturing strategies,this review outlines a translational roadmap toward clinically viable,biomimetic polymeric heart valves capable of addressing the needs of both adult and pediatric patients.Compared to traditional bioprosthetic tissues,advanced polymers offer better resistance to calcification,reduced thrombogenicity,and tunable mechanical properties.展开更多
Background Transcatheter Aortic Valve Implantation(TAVI)has changed the treatment paradigm of the aortic stenosis(AS).It has become the treatment of choice in patients with symptomatic AS and surgical high risk,and a ...Background Transcatheter Aortic Valve Implantation(TAVI)has changed the treatment paradigm of the aortic stenosis(AS).It has become the treatment of choice in patients with symptomatic AS and surgical high risk,and a valid alternative to surgical aortic valve replacement in patients with low and medium surgical risk.Despite numerous evidence on clinical results,indications and benefits,only a few studies analyse it from patient's perspective and the impact of TAVI on them.The objective of this study is to evaluate the experience of patients undergoing TAVI.Methods Cross-sectional,descriptive observational study in two Spanish hospitals,with a establish Nurse TAVI program,with100 patients undergoing TAVI.A specific questionnaire was designed(VALVEX questionnaire)and a pilot study was conducted by a multidisciplinary team of doctors,nurses and patients.The questionnaire was given to patients at 30 days after TAVI procedure during the follow up at the TAVI nurse clinic.Results The study demonstrated a mean satisfaction of 9 for the TAVI program,with 96%of patients that would recommend TAVI to other patients.Patients scored a high satisfaction on the information received prior to the procedure.During the procedure and admission,the satisfaction was high in relation to the care received.During the follow up,satisfaction was high in relation to the role of the TAVI nurse,for the information and continuation of care during the procedure,in reducing anxiety,organising their admission and understanding the process.However,questions with less scores were related to hospital catering,delay between diagnosed and treatment,and patient decision-making process.Conclusion The evaluation of patient experience allows us to improve the information given to the patient during their TAVI process and it can also allow patients to be more relax,aware and prepared for the procedure.Continuous follow up enables monitoring of patient recovery and helps to discuss any doubts improving patient's satisfaction.The use of PREMs and PROMs associated to TAVI pathway combined with an active participation of the patient on the design of the questionnaire is essential for keeping the patient in the centre of the TAVI pathway.展开更多
Cardiac papillary fibroelastoma is a benign heart tumor that,despite its histologically benign nature,can have devastating clinical consequences.Advances in cardiac imaging have made papillary fibroelastoma the most c...Cardiac papillary fibroelastoma is a benign heart tumor that,despite its histologically benign nature,can have devastating clinical consequences.Advances in cardiac imaging have made papillary fibroelastoma the most common primary benign tumor,surpassing cardiac myxoma.These tumors predominantly occur on the surface of heart valves,with the aortic valve being the most frequently affected(44%),followed by the mitral valve(35%)and other locations.Aortic fibroelastomas are the second most common primary cardiac tumor,known for their risk of embolic complications.Surgical excision is recommended for symptomatic lesions,but the management of small and asymptomatic fibroelastomas remains uncertain,particularly in elderly patients with comorbidities.[1-3].展开更多
Aortic stenosis(AS)is the most common valvular heart disease,with a prevalence of over 4%among octogenarians.[1]The prevalence of autopsy-confirmed wild-type transthyretin cardiac amyloidosis(ATTRwt-CA)increases with ...Aortic stenosis(AS)is the most common valvular heart disease,with a prevalence of over 4%among octogenarians.[1]The prevalence of autopsy-confirmed wild-type transthyretin cardiac amyloidosis(ATTRwt-CA)increases with age,accounting for 25%of patients aged 85 years and older in Europe and 12%of patients older than 80 years in Japan.[2,3]Recent studies have reported that ATTRwt-CA coexists in 11%-16%of older patients with AS undergoing transcatheter aortic valve replacement(TAVR).[1,4,5]In a metaanalysis by Ho et al.,[6]the prevalence rates of cardiac amyloidosis,predominantly ATTRwt-CA,in patients with AS and those referred for TAVR or surgical aortic valve replacement(SAVR)were 14.4%and 15.2%,respectively.Conversely,the prevalence of AS in patients with cardiac amyloidosis is 8.7%.Owing to the high surgical risk in patients with both AS and ATTRwt-CA,TAVR may be preferred over SAVR.展开更多
Residual atrioventricular valve regurgitation after correction of complete atrioventricular septal defect(cAVSD)is still not ideal.As a modification of the double-patch method,our technique comprises a suture-bite-wid...Residual atrioventricular valve regurgitation after correction of complete atrioventricular septal defect(cAVSD)is still not ideal.As a modification of the double-patch method,our technique comprises a suture-bite-wide strip of a third patch that is incorporated to the upper margin of the left side of the ventricular septal defect(VSD)patch.This third patch counteracts not only the valvular tissue loss caused by the suture bites but also the rightward displacement of the VSD patch in a bulged fashion that occurs with increased left ventricular pressure after weaning from cardiopulmonary bypass.This unfavorable outcome was addressed with the current technique through augmentation of the left-sided bridging leaflets serving to prevent the separation of them from their corresponding mural leaflets.The concept was applied in two cases with Down syndrome aged 5 months and 6 months,respectively,as a rescue procedure in the same session just after a failed cAVSD repair.Since the immediate-and short-term outcomes of the atrioventricular valves in regard to regurgitation are satisfying,we believe that the technique proposed herein holds promise for the future in terms of tackling residual atrioventricular valve regurgitation.展开更多
A bicuspid aortic valve,from autologous tissue,with growth potential can be constructed using the simple,and reproducible telescoping arterial trunk technique.
文摘Objective: To study early results of hand made fresh (autologous/homologous) pericardial valved conduit in achieving right ventricle to pulmonary artery continuity. Method: Between November 2014 and September 2015, 19 cases, with diagnosis of Tetralogy of Fallot with Pulmonary stenosis (PS) or Pulmonary atresia (PA) underwent intracardiac repair and Right Ventricular Outflow Tract (RVOT) reconstruction with hand made fresh [autologous (n = 2)/ homologous (n = 17)] pericardial valved conduit. Mean age of the patients at time of surgery was 6.37 years (range 3 months to 18 years), mean weight was 18.52 kilograms (range 6 kg to 40 kg) and mean size of the conduit was 20.7 mm (range 16 mm to 24 mm). Results: All patients had a smooth post-operative course, with mean ICU (Intensive Care Unit) stay of 3.6 days (range 3 days to 6 days) and mean post-operative hospital stay 8.5 days (range 7 days to 16 days). Intra-operative and Post-operative echocardiography revealed moderate Pulmonary regurgitation (PR) in one patient, mild PR in 5 patients and no or trace PR in 13 patients. No patient has developed conduit stenosis or calcification till now. Conclusion: Autologous or homologous pericardial valved conduit provides good early results and is especially suitable for developing world because of zero cost. Long term usefulness of such option remains to be confirmed in terms of dilation, calcification and freedom from intervention.
文摘Background Percutaneous aortic valve replacement is a promising strategy in the treatment of patients with aortic valve stenosis. And many kinds of valved stents have been implanted in selected patients worldwide. However, the clinical experience is still limited. We developed a W-model valved stent and evaluated the feasibility and safety of percutaneous implantation of the device in the native aortic valve position.Methods A self expanding nitinol stent with W-model, containing porcine pericardium valves in its proximal part, was implanted in six sheep by means of a 14 French catheter through the right common iliac artery under guidance of fluoroscopy. During stent deployment the original aortic valve was pushed against the aortic wall by the self expanding force of the stent while the new valve was expanded. These sheep were followed up shortly after procedure with supra-aortic angiogram and left ventriculography. Additionally, one sheep was sacrificed after the procedure for anatomic evaluation.Results It was possible to replace the aortic valve in the beating heart in four sheep. The procedure failed in two sheep due to coronary orifice occlusion in one case and severe aortic valve regurgitation in the other case. One sheep was killed one hour after percutaneous aortic valve replacement for anatomic evaluation. There were no signs of damage of the aortic JntJma, or of obstruction of the coronary orifice,Conclusions Percutaneous aortic valve replacement with a W-model valved stent in the beating heart is possible. Further studies are mandatory to assess safety and efficacy of this kind of valved stent in larger sample size and by longer follow-up period.
基金The study was supported by the National Natural Science Foundation of China(81400242 and 81525002)from ESW and HZ,and Program for Distinguished Professor in PUMC from HZ.
文摘Background The prognosis of tetralogy of Fallot with absent pulmonary valve (TOF/APV) without operation is poor. We evaluated the surgical outcome of TOF/APV in a single center. Methods Twenty-two TOF/APV patients underwent complete surgical correction in our hospital. Right ventricular outflow tract reconstruction was performed using bovine jugular vein (BJV)-valved conduit implantation (n=10), homograft-valved conduit implantation (n=2), or monocusp-valve patch (n=10). Health-related quality of life (QOL) was evaluated during follow-up. Results The overall survival at 5 and 10 years was 86.4±7.3% (confidence interval 69.4–97.2%). The survival rates were significantly different between patients with and without bronchial stenosis (40 and 100%, P=0.0003, log-rank test). The survival of patients aged>6 months was higher than those≤6 months (100 vs. 40%, P=0.0003, log-rank test). Patients with BJV-valved conduits had higher systolic gradients from the right ventricle to the pulmonary artery (RV–PA) compared to those with monocusp-valve patches. BJV-valved conduit implantation was a risk factor for post-operative pulmonary-valve stenosis. The QOL score for patients with BJV-valved conduits was lower than those with monocusp-valve patches (P<0.05). No reoperation was performed during follow-up. Conclusions Bronchial stenosis and lower age (≤6 months) were the main factors influencing post-operative survival. The use of a BJV-valved conduit was a main reason for RV–PA restenosis;thus, the use of a BJV-valved conduit may increase the need for repeat intervention and decrease the post-operative quality of life.
基金This work was supported by grants from＇the National Natural Science Foundation of China （No. 81070077 and No. 81270217）, the Beijing High-level Health Expert Foundation （No. 2009-3-44）, and the Capital Medical University Basic and Clinic Cooperative Foundation （No. 11JL09）.
文摘Background The application of pulmonary valved conduit to reconstruct the continuity between right ventricles and pulmonary artery is one of the major surgeries.This study aimed to establish an in vivo model of in situ implantation using pulmonary valved conduit in large animals under off-pump condition to validate the long-term effects of artificial pulmonary valved conduit.Methods Domesticate juvenile male sheep and tissue-engineered poorine pulmonary valved conduit were used for the experiment：30 sheep,weighing （15±3） kg （range 13 to 17 kg） were randomly divided into two groups which were all operated under general anesthesia by off-pump surgery （group 1） and left thoracotomy （group 2）.Two different off-pump surgical methods were used to perform cannulation in sheep pulmonary artery to replace part of sheep pulmonary artery with pulmonary valved conduit which will work together with sheep pulmonary artery and valves.During the experiments,animal survival,complication rates,operating time and blood loss were recorded to compare the results between groups and to establish a surgical method with minimal invasion,simplicity,safety,and high success rates.Results In group 1,a total of 15 cases of surgeries were performed,in which two sheep died; the operative mortality was 13.3％ （2/15）.In group 2,a total of 15 cases of surgeries were performed,and the surgical mortality rate was 0 （0/15）.The operation time and blood loss in group 2 was significantly better than that in group 1.The postoperative echocardiograms showed that,after the surgeries by these two methods,the blood flows were normal,and the valves can open and close freely.Autopsy after 6 months showed that the inner wall and the valves of pulmonary valved conduit were smooth with no thrombus formation.Conclusion These two off-pump methods are feasible and safe with fewer traumas; but the second method is better and particularly suitable for the establishment of a juvenile animal model.
基金supported in part by the‘‘Pioneer”and‘‘Leading Goose”R&D Program of Zhejiang Province(Nos.2022C01132 and 2022C01122)the National Natural Science Foundation of China(No.52005441)+3 种基金the Young Elite Scientist Sponsorship Program by CAST(No.20222024QNRC001)the State Key Laboratory of Mechanical System and Vibration,China(No.MSV202316)the Fundamental Research Funds for the Provincial Universities of Zhejiang,China(RF-A2023007)the Research Project of ZJUT,China(No.GYY-ZH-2023075)。
文摘High Speed on/off Valve(HSV)is an essential component in Aerospace Digital Hydraulic Systems(ADHS),which impose stringent requirements on the dynamic performance and reliability of HSV due to the extreme application environments.However,the faster dynamic leads to increased impact between the spool and valve body,causing severe vibration and wear,which creates a conflict between rapid dynamic and high reliability.To address this problem,a Pre-Excitation Soft Switching Control(PESSC)with both pre-excitation and reverse deceleration functionalities is proposed.The initial current is optimized through pre-excitation to accelerate the opening time,while the application of reverse voltage hastens the decline of electromagnetic force,thereby reducing the spool velocity.The PESSC simultaneously achieves both faster dynamic performance and smaller impact velocity.Moreover,the optimal deceleration voltage parameters are obtained through multi-objective optimization.Experimental results demonstrate that the optimized PESSC shortens the opening time from 2.22 ms to 1.65 ms,reduces the impact velocity by 58.3%,and lowers wear by 55.4%.These findings underline the huge potential of PESSC in enhancing the dynamic performance and reliability of HSVs,offering promising applications in aerospace.
基金supported by the state assignment of Ministry of Science and Higher Education of the Russian Federation(122042700044-6)the Science and Technology Research Partnership for Sustainable Development(SATREPS)project(JPMJSA2001).
文摘Rising temperatures and increased droughts caused by climate change significantly reduce crop yields.Halophytes with different photosynthetic metabolism types have specific mechanisms for resistance to climatic factors.This study analyzed the morphophysiological,biochemical,and molecular-genetic mechanisms of tolerance and adaptation in halophytes,promising candidates for the restoration of salt affected lands in arid and semi-arid areas.Experiments under drought(D)and elevated temperature(eT),as well as their combined action(eT+D),were performed on Atriplex verrucifera M.Bied.(C_(3)plant)and Climacoptera crassa(M.Bieb.)Botsch.(C_(4)-NAD-ME plant)with different types of photosynthesis.The activity of photosystem I(PSI)and the efficiency of photosystem II(PSII)were measured,along with the expression of genes involved in the light(psaA,psaB,psbA,CAB,Fd1,PGR5,and ndhH)and dark(rbcL,Ppc2,and PPDK)reactions of photosynthesis.The content of key carboxylating enzymes ribulose-1,5-bisphosphate carboxylase/oxygenase(Rubisco)and phosphoenolpyruvate carboxylase(PEPC),as well as the photorespiration enzyme glycine decarboxylase(GDC),were assessed.Plant growth and water-salt balance parameters,and activity of enzymes in the malate dehydrogenase(MDH)system nicotinamide adenine dinucleotide(phosphate)(NAD(P))-MDH and NAD(P)-malic enzyme(ME)were also examined.A multivariate analysis of the experimental results revealed that A.verrucifera and C.crassa were both resistant to the effects of these climatic stressors.The tolerance mechanisms of both species were significantly influenced by a high level of photosynthetic plasticity.Nevertheless,differences were observed in the protective mechanisms underlying tolerance.In the C_(3)species,dissipative processes associated with non-photochemical quenching(NPQ)of PSII and MDH system enzymes(malate valves)were activated,particularly under osmotic stress.The negative effects in the C_(3)plants were caused by the combined action of eT+D,which was compensated by an increased expression of rbcL,psaA,CAB,and especially PGR5,i.e.,genes encoding Rubisco large subunit and PSI components:apoproteins A,chlorophyll a/b-associated protein(CAB)of light-harvesting complex,and proton gradient regulation 5(PGR5)protein of the main pathway of cyclic electron transport(CET)around PSI.In C_(4)species,the protective MDH complex was expressed to a lesser extent,but activation of the C_(4)carbon-concentrating mechanism(CCM)and upregulation of PGR5 expression were observed,particularly under the individual action of the factors.Under the combined stress of eT+D,C.crassa exhibited a synergistic effect,where the increase in NPQ level and NAD-ME activity,as well as decrease in NADP-ME activity was less pronounced compared with the effect of singular factors.Comparative physiological,biochemical,and molecular analyses of how C_(3)and C_(4)species response to individual and combined climatic factors provide new insights into sustainable plant adaptation strategies in the face of global climate change.Considering the high nutritional value of these two fodder species,a technological approach could be developed to improve the productivity of salt affected lands.
文摘Background Cryopreserved conduit valved homografts （CVH） have been widely used in surgical treatment of cardiac disease. This study aimed to determine the extent of host cell ingrowth and the durability and immunogenicity of CVH,and to compare the performance of CVH stored at 4℃ and CVH cryopreserved in liquid nitrogen at -196℃.Methods Heterotopic transplants of canine CVH stored at 4℃ （n=14） and cryopreserved in liquid nitrogen （n=14） were made onto the abdominal aorta of recipient dogs. Animals were sacrificed at 7 and 15 days and at 1, 3, 6, 9, and 12months after transplantation to excise the implanted CVHs. Tissue DNA extraction and quantitative polymerase chain reaction （PCR） were performed to calculate the ratio of donor cells and host cells in the CVH. The tissue viability of CVH after implantation was analyzed by detecting alkaline fibroblast growth factor 2 （FGF-2） using immunohistochemical staining and by observation under transmission electron microscope and scanning electron microscope.Results All the animals survived and recovered well. There were few repopulating host cells （0.04-0.83%） in the implanted CVH at 7 or 15 days. The ratio of ingrowing host cells into the CVH continued rising after implantation and reached 40%-47% in the 12th month postoperation. Histology, transmission electron microscopy and FGF-2immunohistochemical staining indicated that fibroblasts and the host＇s endothelial cells were the main cellular elements invading the CVH. There were no significant differences in results between CVH stored at 4℃ and CVH cryopreserved in liquid nitrogen.Conclusions Host cells growing into CVH are very important for maintaining the long-term structure and function of the implanted CVH. There is no significant difference between CVH storing at 4℃ or in liquid nitrogen in regard to the ingrowth of host cells or of morphologic features after CVH allografting.
基金supported by the National Natural Science Foundation of China(No.52175067)the Zhejiang Key Research&Development Project(No.2021C01021)+1 种基金the Natural Science Foundation of Zhejiang Province(No.LY20E050016)the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(CPSF)(No.GZC20241478)。
文摘A high-temperature and high-pressure valve is the key equipment of a wind tunnel system;it controls the generation of high-temperature and high-pressure gas.To reduce the adverse impact of high-temperature and high-pressure gas on the strength of the valve body,a cooling structure is set on the valve seat.This can significantly reduce the temperature of the valve body and valve seat.The effects of its structure on the cooling characteristics and stress of the valve seat are studied,and six main parameters that can completely describe the geometry of the cooling structure are proposed.The central composite design method is used to select sample points,and the multi-objective genetic algorithm(MOGA)method is used for optimal structural design.A modification method according to the main parameters for the valve seat is proposed.The results show that the cooling structure weakens the pressure-bearing capability of the valve seat.Among the six main parameters of the valve seat,the distance from the end face of the lower hole to the Z-axis and the distance from the axis of the lower hole to the origin of the coordinates have the most obvious effects on the average stress of the valve seat.An optimum design value is proposed.This work can provide a reference for the design of high-temperature and high-pressure valves.
文摘BACKGROUND The management of severe symptomatic aortic stenosis has been revolutionized by transcatheter aortic valve replacement(TAVR),offering a minimally invasive alternative to surgical aortic valve replacement(SAVR).However,the compara-tive safety and efficacy of these interventions remain subjects of ongoing investigation.AIM To compare the clinical outcomes and safety of TAVR vs SAVR in patients with severe symptomatic aortic stenosis.METHODS A systematic review and meta-analysis were conducted according to PRISMA guidelines.Randomized controlled trials(RCTs)comparing TAVR and SAVR were identified from databases including PubMed,Scopus,and Web of Science up to May 31,2024.Data were extracted on clinical outcomes,including mortality,procedural compli-cations,and post-procedure adverse events.Risk ratios(RRs)with 95%CIs were calculated using a random-effects model.RESULTS A total of 10 RCTs were included.TAVR demonstrated a significantly lower risk of acute kidney injury(RR:0.33;95%CI:0.25–0.44),major bleeding(RR:0.37;95%CI:0.30–0.46),and new-onset atrial fibrillation(RR:0.44;95%CI:0.34–0.57)compared to SAVR.However,TAVR was associated with higher risks of new permanent pacemaker implantation(RR:3.49;95%CI:2.77–4.39),major vascular complications(RR:2.47;95%CI:1.91–3.21),and paraval-vular leaks(RR:4.15;95%CI:3.14–5.48).Mortality at 30 days was comparable(RR:0.95;95%CI:0.78–1.15),but long-term mortality was slightly higher with TAVR in some analyses(RR:1.23;95%CI:1.01–1.49).Rates of stroke(RR:0.97;95%CI:0.81–1.17)and myocardial infarction(RR:0.91;95%CI:0.67–1.24)were similar between the groups.CONCLUSION TAVR offers a less invasive option with significant benefits in reducing acute kidney injury,major bleeding,and new-onset atrial fibrillation,making it particularly advantageous for high-risk surgical candidates.However,higher risks of permanent pacemaker implantation,vascular complications,and paravalvular leaks highlight the need for individualized patient selection and shared decision-making to optimize outcomes.
文摘BACKGROUND Valvular heart disease affects more than 100 million people worldwide and is associated with significant morbidity and mortality.The prevalence of at least moderate valvular heart disease is 2.5%across all age groups,but its prevalence increases with age.Mitral regurgitation and aortic stenosis are the most frequent types of valvular heart disease in the community and hospital context,res-pectively.Surgical valve replacement(or mitral valve repair)is the standard of care for treating heart valve disease.However,the replacement of a prosthetic heart valve can lead to complications,either in the peri-procedural phase or in the long-term follow-up period.CASE SUMMARY We present a case of a 71-year-old female patient with a history of mitral valve replacement and warfarin anti-coagulation therapy.She was admitted to the intensive care unit due to spontaneously reperfused ischemic stroke of probable cardioembolic etiology.A dysfunctional mitral prosthesis was identified due to malfunction of one of the fixed discs.Furthermore,a possible microthrombotic lesion was suspected.Therefore,systemic thrombolysis was performed with subsequent normalization of mitral disc opening and closing.CONCLUSION This case underscores the critical importance of a multidisciplinary approach for timely decision-making in critically ill patients with prosthetic valve complications.
文摘Background There is scarce data about comparisons between geriatric assessment tools in patients with aortic stenosis(AS).We aimed to describe the geriatric profile of patients with AS undergoing transcatheter aortic valve implantation(TAVI)and to analyze the ability of different tools for predicting clinical outcomes in this context.Methods This was a single center retrospective registry including patients with AS undergoing TAVI and surviving to hospital discharge.The primary endpoint was all-cause mortality or need for urgent readmission one year after TAVI.Results A total of 377 patients were included(mean age of 80.4 years).Most patients were independent or mildly dependent,with an optimal cognitive status.The proportion of frailty ranged from 17.6%to 49.8%.A total of 20 patients(5.3%)died and 110/377 patients(29.2%)died or were readmitted during follow up.Overall,most components of the geriatric assessment showed an association with clinical outcomes.Disability for instrumental activities showed a significant association with mortality and a strong association with the rate of mortality or readmission.The association between frailty and clinical outcomes was higher for short physical performance battery(SPPB),essential frailty toolset(EFT)and the frailty index based on comprehensive geriatric assessment(IF-VIG)and lower for Fried criteria and FRAIL scale.Conclusions AS patients from this series presented a good physical performance,optimal cognitive status and a reasonably low prevalence of frailty.The best predictive ability was observed for disability for instrumental activities and frailty as measured by the EFT,SPPB and the IF-VIG.
基金The Fundamental Research Funds for the Central Universities(JD2423)。
文摘Pump valve pipeline vibration brings serious safety hazards to the operation of the equipment,for the pump valve system in the process of variable flow,variable speed,variable openings lead to excessive pipeline vibration.An active damping device(ADD)is used to the vibration of the pump valve pipeline system to apply the control force,to achieve the active control of the pipeline vibration.A pump-valve pipeline vibration test bench was built to compare the control effect of active damping device on pipeline vibration under different pump valve working conditions,and the results show that applying ADD control could effectively suppress the vibration of the pump valve pipeline and enhance the stability of the equipment during operation.At different pump operating rotation frequencies,the vibration amplitude of the pump valve pipeline in working frequency and its multiple frequencies are also effectively suppressed,with the maximum amplitude reduction of more than 60%.For the valve vibration caused by different operating openings,the vibration of the highest reduction of 68%,and the centrifugal pump drive shaft vi-bration reduced by up to 73%,which provides a new idea for vibration control of pump valve pipeline system.
基金supported by the National Key Research&Development Program of China(No.2023YFF0721304)the Key Research&Development Program of Jiangsu Province(No.2021015-4),China。
文摘Gifford-McMahon-type pulse-tube cryocoolers(GM-PTCs)working at liquid helium temperatures are promising in quantum technology and cryogenic physics for their high reliability and minimal vibration.These features stem from the fact that there are no extra moving parts introduced into the system.The rotary valve is a key component in GM-PTCs that transfers the output exergy from the compressor to the cold head.Because a low Carnot efficiency of 1.58%is achieved at liquid helium temperatures,optimizing the rotary valve is crucial for improving the efficiency of GM-PTCs.In this regard,an exergy-loss analysis method is proposed in this paper to quantitatively obtain the leakage loss and viscosity loss of a rotary valve by experimental measurements.The results show that viscosity loss accounts for more than 97.5%of the total exergy loss in the rotary valve,and that it is possible to improve the structure of the rotary valve by expanding the flow area by 1.5 times.To verify the method,the cooling temperature and power of a remote two-stage GM-PTC were monitored,with original or optimized rotary valves installed.The experimental results show that compared to the original rotary valve,the optimized rotary valve can improve the cooling efficiency of a GM-PTC by 16.4%,with a cooling power of 0.78 W at 4.2 K.
文摘Pediatric heart valve replacement(PHVR)remains a challenging procedure due to the uniqueanatomical and physiological characteristics of children,including growth and development,as well asthe long-term need for durable valve function.This review provides an overview of both surgical andtranscatheter options for aortic,mitral,pulmonary,and tricuspid valve replacements in pediatric patients,highlighting the indications,outcomes,and advancements in technology and technique.Surgical valvereplacement traditionally involves the implantation of biological or mechanical prosthetic valves,withbiologicalvalves beingpreferred in children to reduce the need for lifelong anticoagulation therapy.However,the limitation ofbiological prostheses,nanely their inability to grow with the child,necessitates the frequentneed for reoperations.Recent innovations in valve engineering,such as the development of tissue engineeredand expandable valves,aim to address these issues.Transcatheter valve replacement(TVR)has emergedas a promising alternative,particularly for patients with complex anatomy or those who are high-risk fortraditional surgery.While the use of transcatheter devices in children remains limited due to the smallervascular size and limited long-termn data,several studies have demonstrated the feasibility and safety ofthe procedure in certain patient populations.Despite these advancements,challenges related to valvesize,durability,and the need for individualized treatment planning persist.The future of pediatric heartvalve replacemnent will likely involve a multidisciplinary approach combining surgical,transcatheter,andregenerative medicine strategies,aimed at optimizing outcomes,reducing the need for reinterventions,andimproving long-term quality of life for pediatric patients with valvularheart disease.This article discussesall options availab le for patients with valvular dysfunction,making it easy for parents/patients to go to as areference source of information.
文摘Valvular Heart Disease(VHD),including stenosis and regurgitation,is a significant contributor to global cardiovascular morbidity.Current prosthetic solutions mechanical and bioprosthetic heart valves each present major limitation.Mechanical valves require lifelong anticoagulation due to thrombogenicity,while bioprosthetic valves suffer from structural degeneration and limited durability.Polymeric Heart Valves(PHVs)have emerged as promising alternatives,aiming to integrate the mechanical resilience of synthetic materials with the biocompatibility and hemodynamic performance of natural valves.Recent studies have explored advanced polymers such as Polyhedral Oligomeric Silsesquioxane–Polycarbonate–Urea–Urethane(POSS-PCU),Silicone–Polyurethane Urea(SiPUU),and nanocomposites like Polyvinyl Alcohol(PVA)and SIBS for their enhanced thromboresistance,calcification resistance,and long-term mechanical durability.Complementary to material innovation,fabrication methods such as 3D printing,Melt Electrospinning Writing(MEW),and Focused Rotary Jet Spinning(FRJS)offer patient-specific designs and microstructural control.This review systematically compares traditional and next-generation prostheses,examines mechanical and biological performance,and discusses critical design challenges including porosity,thrombogenicity,and leaflet calcification.Finite Element Analysis(FEA)and Computational Fluid Dynamics(CFD)are highlighted for optimizing design and simulating physiological conditions.By presenting recent preclinical progress and manufacturing strategies,this review outlines a translational roadmap toward clinically viable,biomimetic polymeric heart valves capable of addressing the needs of both adult and pediatric patients.Compared to traditional bioprosthetic tissues,advanced polymers offer better resistance to calcification,reduced thrombogenicity,and tunable mechanical properties.
基金funded by a IBYE23_0002 grant supported by Instituto de investigación biom-édica de Salamanca IBSAL,Castilla y León (Spain) and by a GRS 2860/A1/2023 by Gerencia Regional de Salud o f Castilla y León (Spain)。
文摘Background Transcatheter Aortic Valve Implantation(TAVI)has changed the treatment paradigm of the aortic stenosis(AS).It has become the treatment of choice in patients with symptomatic AS and surgical high risk,and a valid alternative to surgical aortic valve replacement in patients with low and medium surgical risk.Despite numerous evidence on clinical results,indications and benefits,only a few studies analyse it from patient's perspective and the impact of TAVI on them.The objective of this study is to evaluate the experience of patients undergoing TAVI.Methods Cross-sectional,descriptive observational study in two Spanish hospitals,with a establish Nurse TAVI program,with100 patients undergoing TAVI.A specific questionnaire was designed(VALVEX questionnaire)and a pilot study was conducted by a multidisciplinary team of doctors,nurses and patients.The questionnaire was given to patients at 30 days after TAVI procedure during the follow up at the TAVI nurse clinic.Results The study demonstrated a mean satisfaction of 9 for the TAVI program,with 96%of patients that would recommend TAVI to other patients.Patients scored a high satisfaction on the information received prior to the procedure.During the procedure and admission,the satisfaction was high in relation to the care received.During the follow up,satisfaction was high in relation to the role of the TAVI nurse,for the information and continuation of care during the procedure,in reducing anxiety,organising their admission and understanding the process.However,questions with less scores were related to hospital catering,delay between diagnosed and treatment,and patient decision-making process.Conclusion The evaluation of patient experience allows us to improve the information given to the patient during their TAVI process and it can also allow patients to be more relax,aware and prepared for the procedure.Continuous follow up enables monitoring of patient recovery and helps to discuss any doubts improving patient's satisfaction.The use of PREMs and PROMs associated to TAVI pathway combined with an active participation of the patient on the design of the questionnaire is essential for keeping the patient in the centre of the TAVI pathway.
文摘Cardiac papillary fibroelastoma is a benign heart tumor that,despite its histologically benign nature,can have devastating clinical consequences.Advances in cardiac imaging have made papillary fibroelastoma the most common primary benign tumor,surpassing cardiac myxoma.These tumors predominantly occur on the surface of heart valves,with the aortic valve being the most frequently affected(44%),followed by the mitral valve(35%)and other locations.Aortic fibroelastomas are the second most common primary cardiac tumor,known for their risk of embolic complications.Surgical excision is recommended for symptomatic lesions,but the management of small and asymptomatic fibroelastomas remains uncertain,particularly in elderly patients with comorbidities.[1-3].
文摘Aortic stenosis(AS)is the most common valvular heart disease,with a prevalence of over 4%among octogenarians.[1]The prevalence of autopsy-confirmed wild-type transthyretin cardiac amyloidosis(ATTRwt-CA)increases with age,accounting for 25%of patients aged 85 years and older in Europe and 12%of patients older than 80 years in Japan.[2,3]Recent studies have reported that ATTRwt-CA coexists in 11%-16%of older patients with AS undergoing transcatheter aortic valve replacement(TAVR).[1,4,5]In a metaanalysis by Ho et al.,[6]the prevalence rates of cardiac amyloidosis,predominantly ATTRwt-CA,in patients with AS and those referred for TAVR or surgical aortic valve replacement(SAVR)were 14.4%and 15.2%,respectively.Conversely,the prevalence of AS in patients with cardiac amyloidosis is 8.7%.Owing to the high surgical risk in patients with both AS and ATTRwt-CA,TAVR may be preferred over SAVR.
文摘Residual atrioventricular valve regurgitation after correction of complete atrioventricular septal defect(cAVSD)is still not ideal.As a modification of the double-patch method,our technique comprises a suture-bite-wide strip of a third patch that is incorporated to the upper margin of the left side of the ventricular septal defect(VSD)patch.This third patch counteracts not only the valvular tissue loss caused by the suture bites but also the rightward displacement of the VSD patch in a bulged fashion that occurs with increased left ventricular pressure after weaning from cardiopulmonary bypass.This unfavorable outcome was addressed with the current technique through augmentation of the left-sided bridging leaflets serving to prevent the separation of them from their corresponding mural leaflets.The concept was applied in two cases with Down syndrome aged 5 months and 6 months,respectively,as a rescue procedure in the same session just after a failed cAVSD repair.Since the immediate-and short-term outcomes of the atrioventricular valves in regard to regurgitation are satisfying,we believe that the technique proposed herein holds promise for the future in terms of tackling residual atrioventricular valve regurgitation.
基金funded by internal grants from the Ward Family Heart Center.
文摘A bicuspid aortic valve,from autologous tissue,with growth potential can be constructed using the simple,and reproducible telescoping arterial trunk technique.
