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A delayed wound healing process can lead to detrimental complications in chronic wound patients such as tissue necrosis and systemic infections. Application of immunonutrition (IN) in experimental animal models and chronic wound patients has shown promising and improved wound healing processes. IN restores the supply of essential nutrients that are critical for cell growth and tissue repair in the wounded subjects. Several commonly found nutrients in IN formulations include polyunsaturated fatty acids (PUFAs), essential amino acids, trace elements such as zinc and vitamins. Recently, some studies suggested the use of traditionally used herbs like curcumin in IN recipes due to its efficient wound healing properties. The roles and functions of IN in wound healing encompass recruitment of white blood cells, platelets and fibroblasts into the wounded area during the coagulation and inflammation phases, enhancement of fibroblast proliferation, collagen synthesis and neovascularization in the proliferation phase; and lastly, regulation of tissue re-epithelization for wound closure and recovery. In this review, the roles and functions of individual nutrients were deliberately discussed alongside their mechanisms of action in wound healing. This aims to provide a more holistic insight into the potentials of those nutrients when used as part of IN for major wound patients. Despite its remarkable effects in wound healing, several criteria should be considered in an IN formulation: the type and severity of wounds, administration timing and mode of administration, and concoction of immune-boosting nutrients in order to ensure the optimal wound healing effects. Keywords: Wound healing; immunonutrition; PUFAs; amino acids; vitamins

Purpose Formal structured leadership training is increasingly incorporated as a regular fixture in developed nations to produce competent leaders to ensure the provision of quality patient care. However, most low- and middle-income countries (LMICs) rely on one-off external training opportunities for selected individuals as they lack the necessary resources to implement long-term training for a wider pool of potential health care leaders. This case study shares the establishment process of the Talent Grooming Programme for technical health care professionals (TGP), a three-year in-house leadership training programme specially targeted at potential health care leaders in Malaysia. Design/methodology/approach This case study aims to share a comprehensive overview of the ideation, conceptualisation and implementation of TGP. The authors also outlined its impact from the individual and organisational perspectives, besides highlighting the lessons learned and recommendations for the way forward. Findings TGP set out to deliver experiential learning focusing on formal training, workplace experiences, practical reflection and mentoring by supervisors and other esteemed leaders to fulfil the five competency domains of leadership, organisational governance, communication and relationship, professional values and personal values. The successes and challenges in TGP programme delivery, post-training assessment, outcome evaluation and programme sustainability were outlined. Practical implications The authors’ experience in setting up TGP provided valuable learning points for other leadership development programme providers. As for any development programme, a continuous evaluation is vital to ensure its relevance and sustainability. Originality/value Certain aspects of TGP establishment can be referenced and modified to adapt to country-specific settings for others to develop similar leadership programme, especially those in LMICs.

In 2016, the Ministry of Health (MOH) Malaysia has introduced a new programme to prevent and reduce the occurrence of non-communicable diseases (NCDs) as well as related risk factors in the work place environment known as KOSPEN Plus. This study aims to evaluate the awareness and perception of KOSPEN Plus programme after 3 years of implementation in MOH health facilities, government and private agencies in Malaysia. A cross sectional study design was employed in the study. All health facilities, government and private agencies which had implemented KOSPEN Plus programme between 2016 and 31 December 2018 in all states in Malaysia were invited to participate in the study. The computer assisted self-interview (CASI) using the pre-tested self-administered questionnaire in the electronic form was used. A total of 362 health facilities, government and private agencies which had implemented KOSPEN Plus programme was involved in this study. Overall, more than 80% of facilities/agencies in this study implemented six out of the eight scopes of KOSPEN Plus. The survey was planned with the goal of obtaining data to support the Ministry of Health in reviewing the present health activities related to workers health in Malaysia and make necessary improvement to the programme.

Introduction: Exposure to traumatic events in the form of harassment, aggression, litigation, medication error, mass disaster and life-threatening incident at workplace may lead to poor psychological wellbeing and burnout among healthcare workers. This study looked at the occurrence of debriefing session following traumatic events experienced by the AMO and its effect on their level of burnout. Results: 1839 AMO responded to the questionnaire and 602 reported to have experienced traumatic event at workplace. Nearly half of the AMO with history of traumatic event (n=297, 47.4%) suffered fromburnout. Only a quarter (n=154, 25.5 %) of the AMO received some form of debriefing and psychological support following the traumatic event. The result also showed that AMO who have been debriefed after traumatic event are 1.53 times less likely to experience burnout as compared to those who did not receive any support. Discussion/Conclusion: Debriefing session is imperative in mitigating the psychological impact of stress, anxiety, and fear among personnel involved in traumatic events. Left unattended, these symptoms may progress to burnout and post-traumatic stress disorder (PTSD). Support like counselling, peer support and debriefing training are measures that can be implemented for HCW experiencing traumatic events. &nbsp

Physician burnout has been recognized as a public health crisis. However, there is a paucity of burnout studies in the context of medical internship. We assessed the prevalence and relationship between various training characteristics, personal variables, resilience, and coping with burnout in a cross-sectional study involving 837 interns from ten hospitals across Malaysian healthcare system. The instrument package included demographic questions, the Connor–Davidson Resilience Scale, Brief COPE and the Copenhagen Burnout Inventory. A total of 754 (90.1%) interns completed the inventories. We found a high prevalence of personal-related (73.3%), work-related (69.1%), and patient-related (43.4%) burnout among Malaysian interns. Multivariable analysis showed female gender (odds ratio (OR):1.50, 95% confidence interval (CI): 1.02–2.20), prior work experience (OR: 1.56, 95% CI: 1.05–2.30), and irregular spirituality routines (OR: 1.97, 95% CI: 1.30–2.99) were associated with increased odds of personal-related burnout. Irregular spirituality routines (OR: 2.24, 95% CI: 1.49–3.37) were associated with work-related burnout, while living with other people (OR: 1.77, 95% CI: 1.15–2.73) was associated with patient-related burnout. Lower resilience levels and avoidant copings were associated with personal-, work-, and patient-related burnout. Burnout prevalence among interns is high. The findings support the value of individual-targeted alongside organizational-targeted intervention in burnout reduction. As burnout is prevalent in both years of internship training, ongoing burnout prevention and wellbeing measures are deemed necessary.

Strengthening the health systems through gaps identification is necessary to ensure sustainable improvements especially in facing a debilitating outbreak such as COVID-19. This study aims to explore public perspective on health systems’ response towards COVID-19, and to identify gaps for health systems strengthening by leveraging on WHO health systems’ building blocks. A qualitative study was conducted using open-ended questions survey among public followed by in-depth interviews with key informants. Opinions on Malaysia’s health systems response towards COVID-19 were gathered. Data were exported to NVIVO version 12 and analysed using content analysis approach. The study identified various issues on health systems’ response towards COVID-19, which were then mapped into health systems’ building blocks. The study showed the gaps were embedded among complex interactions between the health systems building blocks. The leadership and governance building block had cross-cutting effects, and all building blocks influenced service deliveries. Understanding the complexities in fostering whole-systems strengthening through a holistic measure in facing an outbreak was paramount. Applying systems thinking in addressing gaps could help addressing the complexity at a macro level, including consideration of how an action implicates other building blocks and approaching the governance effort in a more adaptive manner to develop resilient systems.

The deteriorating nature of severe functional tricuspid regurgitation (FTR) has led to the heightened interest in this pathology. However, therapies are heterogeneous and an ideal technique is uncertain. The hemodynamic impact on the cardiac chamber following therapeutic repairs has not been well studied, while its analysis could be used to predict the treatment success. In this study, the hemodynamics of the right ventricle (RV) after 1) clover edge-to-edge tricuspid repair, and 2) double orifice tricuspid repair was evaluated in three right heart models using an ex vivo pulsatile platform emulating severe FTR with the aid of stereoscopic particle image velocimetry. Although all repairs substantially reduced tricuspid regurgitant area, they resulted in a more than 50% reduction in diastolic tricuspid valve (TV) opening area. Splitting the TV orifice into multiple smaller orifices by both repairs eliminated the ring-shaped vortical structure inside the RV observed in FTR cases. Postrepair RV domain was mostly occupied with irregular vortical features and isolated vortex residuals. Moreover, vortical features varied among repair samples, indicating enhanced sensitivity of RV flow to postrepair TV morphology. Compared with clover repair, double orifice subjected the RV to enhanced swirling motions and exposed more regions to vortical motions, potentially indicating better rinsing and lower risk of mural thrombus formation. Double orifice repair increased the levels of RV mean kinetic energy and viscous energy loss than those observed in clover repair, although the impact of these on the cardiac efficiency remains unclear. These preliminary insights could be used to improve future treatment design and planning. NEW & NOTEWORTHY While clover and double orifice tricuspid repairs markedly improved leaflet coaptation, they substantially reduced diastolic tricuspid opening area. Postrepair right ventricle (RV) exhibited specific hemodynamic traits, including the loss of ring-shaped vortical structure and the enhanced sensitivity of RV flow to postrepair tricuspid valve morphology. Compared with clover technique, double orifice repair led to higher swirling motions in the RV domain, which could indicate lower risk of mural thrombus formation.

There has been a resurgence of interest in the treatment of severe functional tricuspid regurgitation (FTR) due to the awareness of its poor outcomes and potential percutaneous therapies. Kay bicuspidization has been adapted in percutaneous therapies but its clinical outcome remains uncertain. The present study evaluates the efficacy of Kay repair in a novel ex vivo pulsatile system. Porcine tricuspid valve (TV) (n = 3) was extracted and incorporated into a patient-specific silicon right ventricle (RV) emulating severe FTR, on which Kay repair was subsequently performed. TV area metrics and RV hemodynamic assessment by means of stereo-scopic particle image velocimetry were quantified in both FTR and post-repair conditions. Bicuspidization led to significant increase in cardiac output although the overall increment due to this approach alone was generally small, possibly due to existence of residual TR and the large reduction in TV opening area. Kinetic energy and viscous loss levels were increased post-repair, especially during diastolic filling. Main vortex structures generally maintained post-procedural. However, there was enhanced swirling motion in larger RV domain. Although this might reduce mural-thrombus risk, the relatively more complex vortex phenomenon likely resulted in elevated viscous loss observed and may potentially impact long-term adaptation. The RV hemodynamic alteration after tricuspid repair could be used to predict the success of these future transcatheter solutions.

Despite modern medicine, there is an increasing trend for cases of the bacterial infection leptospirosis, and this has led to the exploration of alternative medicines from various sources including plants. The aim of this study was to investigate the in vitro anti-leptospiral activity of Phyllanthus amarus extracts alone and combined with penicillin G, ceftriaxone, and doxycycline. Antimicrobial susceptibility testing was performed using the microdilution broth technique upon methanol extract (ME), aqueous extract (AE), and antibiotics against the Leptospira interrogans serovars Australis, Bataviae, Canicola, and Javanica, to determine minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs). The results were analyzed using an ELISA microplate reader combined with microscopic analysis. Synergy testing using a checkerboard assay was performed to determine the fractional inhibitory concentration index values of extracts combined with antibiotics against leptospires. Scanning electron microscopy (SEM) was used to investigate morphological changes of leptospires caused by potential anti-leptospiral agents alone and combined with antibiotics. The MICs and MBCs for P. amarus extracts ranged from 100 to 400 µg/mL for AEs and from 400 to 800 µg/mL for MEs. Penicillin G was the most effective anti-leptospiral drug, with MICs and MBCs ranging from

Introduction The spread of COVID-19 rapidly brought unprecedented strains on health systems. The establishment of an effective and real-time surveillance system is critical to facilitate timely planning and outbreakmanagement. Objective To identify areas for improvements in Malaysia’s health surveillance system during outbreak. MethodUsing the COVID-19 Strategic Preparedness and Response Plan document, an online survey consistingof open-ended questions were sent out to the publicand identified key informants between late March and mid-April 2020. The responses were exported to NVIVO-12 software and using content analysis, issues related to Malaysia’s health system response to COVID-19 were identified. Issues on surveillance were deductively grouped based on the surveillance domains identified (System Structure, Core Function, Surveillance Quality & Support Function) in World Health Organization document. ResultsThe survey captured responses from 16 key informants and 60 public respondents. We identified areas for improvement related to the four surveillance domains. Areas requiringimmediateversuslong-termattentionwerealso highlighted. For example, mobilisation of healthcare personnel to highly affected districts to facilitate sampling process, contact tracing and data analysis required urgent action. Conversely, the development of competency in the surveillance processes needed continuous regular training over time. ConclusionHealth system issues for an outbreak need to be prioritised and addressed. Learning from past experiences is imperative to strengthen our health system including surveillance activities to better manage future outbreaks.

Introduction The prevalence of psychological distress is increasing worldwide. Stressful working environments and high expectations in medical practice put doctors at high risk of depression, anxiety, and stress, especially among medical interns. Effective coping strategies may reduce psychological distress in the clinical setting. This study aimed to determine the prevalence of psychological distress and its association with coping strategies among medical interns in Malaysia. Method A total of 431 medical interns at 26 Malaysian Ministry of Health hospitals participated in this cross‐sectional study in 2017. Self‐administered questionnaires consisting of sociodemographic characteristics, items from DASS and BRIEF COPE were used. Descriptive analysis was done followed by further analysis with chi‐square and Spearman correlation tests. Results The prevalence of stress, anxiety, and depression was 29.7%, 39.9%, and 26.2%, with a significantly higher prevalence among female and younger interns. Three‐quarters of them (73.1%) applied problem‐focused strategies as the main coping mechanism. Emotion‐focused coping strategies showed a significant but weak correlation with anxiety and stress whereas avoidance‐based coping strategies were significantly correlated with depression, anxiety, and stress. Discussion Medical internship is a highly grueling period. Besides emphasizing clinical competency, internship training should also impart the practice of healthy coping mechanisms. The vulnerable groups of females and younger interns should be taught positive coping skills so that they are empowered to handle any stressors on their personal and professional lives. Optimum psychological wellbeing of the medical interns can improve the overall work performance and quality of care for patients.

The concept of heterotopic implantation of transcatheter tricuspid valve is new and has shown promising results thus far. While the Reynolds shear stress values measured in the vicinity of this valve are relatively low, the values at some time points are higher than the threshold of platelet activation. Hence, in this study, we aim to reduce these values with an innovative stent design. It was shown that the Reynolds shear stress values measured were lower than those of valves made of generic stent design and the maximum Reynolds shear stress values in the vicinity of the valves was very low (∼10 dynes/cm2 ). The results also depicted the interesting flow phenomenon of this non-physiological treatment approach. Thus, this study has shown that bicaval valves could potentially be considered as a minimally invasive option to treat tricuspid regurgitation and valve design improvements could reduce the flow disturbances that were observed.

The increased understanding of right heart diseases has led to more aggressive interventions to manage functional tricuspid regurgitation (FTR). In some cases of FTR, prosthetic valve replacement is typically considered when concomitant organic components or significant geometrical distortions are involved in the pathology of the tricuspid valve. However, little is known of the performance of current devices in the right heart circulation. In this study, a novel in vitro mock circulatory system that incorporated a realistic tricuspid valve apparatus in a patient-specific silicon right ventricle (RV) was designed and fabricated. The system was calibrated to emulate severe FTR, enabling the investigation of RV hemodynamics in pre- and post-implantation of tri-leaflet tissue implant and bi-leaflet mechanical implant. 2D particle imaging velocimetry was performed to visualize flow and quantify relevant hemodynamic parameters. While our results showed all prosthetic implants improved cardiac output, these implants also subjected the RV to increased turbulence level. Our study also revealed that the implants did not create the optimal behavior of fluid transfer in the RV as we expected. Among the implants tested, tissue implant created the most dominant vortices, which persisted throughout diastole; its observed strong negative vortex could lead to increase energy expenditure due to undesired fluid direction. In contrast, both native valve and mechanical implant had both weaker vortex formation as well as more significant vortex dissipation. Interestingly, the vortex dissipation of native valve was associated with streamlined flow pattern that tended towards the pulmonary outlet, while the mechanical implant generated more regions of flow stagnation within the RV. These findings heighten the imperative to improve designs of current heart valves to be used in the right circulation.

Heterotopic implantation of transcatheter tricuspid valve is a new treatment option for tricuspid regurgitation. Transcatheter tricuspid valves (inferior and superior) are implanted at the cavo-atrial junctions (CAJ) in order to avoid the challenging task of anchoring the valve in the complex tricuspid valve annulus. However, little is known about the complex loading that the valve stent can withstand at the cavo-atrial junction, which is critical for fatigue life prediction and device development. In this study, we developed a finite element based fatigue model taking into account the major fatigue loads that may be acting upon the two caval stents, after deployment. The simulation results showed that both stent designs had a fatigue safety factor (FSF) greater than 1 under these complex loading conditions. It was also observed from our simulation that leaflets loads contributed more towards the fatigue of valved stents compared to the other loads. The fatigue model presented in this study provides a simple, fast and cost-effective tool to quantitatively determine the fatigue resistance of caval valved stents subjected to cyclic loads. The simulated bench testing proposed here can be of great value to the design and development of new prosthetic cava stented valves.

Heterotopic implantation of transcatheter tricuspid valve is a new treatment option for tricuspid regurgitation. Transcatheter tricuspid valves are implanted onto the cavoatrial junction in order to avoid the challenging task of anchoring the valve onto the complex tricuspid valve annulus. However, little is known about optimum extent of oversizing of the valved stent in a vena cava. In this study, we implanted valves of the same diameter onto the larger sized inferior vena cava (IVC) and a smaller sized superior vena cava (SVC). The valve in the IVC was oversized by 10.7% while the valve in the SVC was oversized by 21.6%. Finite element analysis was performed (i) to assess the strain on the nitinol stent during manufacturing and deployment; (ii) the stents were deployed in a patient-specific vena cava model and the intramural stress of the vena cava was calculated computationally. These valves were fabricated and placed in a silicone model of a patient-specific right atrium which was part of a mock circulatory system that emulated the patho-physiological flow rate and pressure of a patient with tricuspid regurgitation. Flow measurements were conducted by particle image velocimetry (PIV). It was found that the maximum crimping strain on the nitinol stent was 6.85% which was lower than the critical threshold of 10%. The maximum stress on the vena cava was located at the spot where the hooks met the wall. The maximum stress on the IVC was 0.5098 MPa while the maximum stress on the SVC was 0.7 MPa. The maximum Reynolds shear stress (mRSS) in the vena cava was found to be higher in the IVC than SVC with the highest mRSS being 1741 dynes/cm(2) found in the region of high flow during the peak flow phase. The overtly oversized valve in the SVC did not cause flow disturbances and exhibited mostly laminar flows. The mRSS at the downstream of the vena cava valve and the middle of the atrium remained at low magnitudes. However, velocity fluctuations were high in the IVC in all the time points measured. In conclusion, oversizing the valve may assist anchorage; yet, careful consideration should be taken in choosing the extent of oversizing as it may lead to adverse effects.

Arterio-venous grafts (AVGs), the second best option as long-term vascular access for hemodialysis, face major issues of stenosis mainly due to development of intimal hyperplasia at the venous anastomosis which is linked to unfavorable hemodynamic conditions. We have investigated computationally the utility of a coupled sequential venous anastomotic design to replace conventional end-to-side (ETS) venous anastomosis, in order to improve the hemodynamic environment and consequently enhance the patency of AVGs. Two complete vascular access models with the conventional and the proposed venous anastomosis configurations were constructed. Three-dimensional, pulsatile blood flow through the models was simulated, and wall shear stress (WSS)-based hemodynamic parameters were calculated and compared between the two models. Simulation results demonstrated that the proposed anastomotic design provides: (i) a more uniform and smooth flow at the ETS anastomosis, without flow impingement and stagnation point on the artery bed and vortex formation in the heel region of the ETS anastomosis; (ii) more uniform distribution of WSS and substantially lower WSS gradients on the venous wall; and (iii) a spare route for the blood flow to the vein, to avoid re-operation in case of stenosis. The distinctive hemodynamic advantages observed in the proposed anastomotic design can enhance the patency of AVGs.

Severe tricuspid regurgitation (TR) is life-threatening but is often undertreated. Many patients with severe TR are denied heart valve replacement surgery because their old age or comorbidities predispose them to a higher risk of surgical complications associated with open-heart surgery. With the advent of transcatheter technology, it is now possible to deliver the valve to the desired location without the need for open-heart surgery. However, presently, there is no commercially available transcatheter tricuspid valve. This may be due to the complex tricuspid valve anatomy, which lacks an anchorage zone for the percutaneous valves. In view of this drawback, we have recently developed and tested two percutaneous caval heart valves that are designed to deploy at the vena cava and atrium junction. The hemodynamic characteristics of these valves are tested in a mock circulatory system with patient-specific silicone atrium and vena cava, which emulates the physiological pressure and flow conditions at the right side of the human heart. Particle imaging velocimetry results showed that flow velocity and the associated Reynolds shear stress (RSS) and the turbulent kinetic energy (TKE) downstream of the valves increased after the implantation of the valves. A maximum flow velocity of 0.94 m/s was observed at the region downstream of the percutaneous valve at the superior vena cava (SVC). Maximum RSS value of 2076.1 dynes/cm(2) was observed downstream of the valve at the inferior vena cava during the deceleration phase while maximum TKE measured was 572.6 J/m(3) at the upstream of the valve in the SVC during the peak flow phase. While these values appear high, they are significantly lower than those reported in prosthetic mitral and aortic valves. Hence, caval stented valves can be potentially considered as a minimally invasive option to treat TR.

Intra-ventricular flow dynamics has recently emerged as an important evaluation and diagnosis tool in different cardiovascular conditions. The formation of vortex pattern during the cardiac cycle has been suggested to play important epigenetic and energy-modulation roles in cardiac remodelling, adaptations and mal-adaptations. In this new perspective, flow alterations due to different cardiovascular procedures can affect the long-term outcome of those procedures. Especially, repairs and replacements performed on atrioventricular valves are likely to exert direct impact on intra-ventricular flow pattern. In this review, current consensus around the roles of vortex dynamics in cardiac function is discussed. An overview of physiological vortex patterns found in healthy left and right ventricles as well as post-operative ventricular flow phenomenon owing to different atrioventricular valvular procedures are reviewed, followed by the summary of different vortex identification schemes used to characterise intraventricular flow. This paper also emphasises on future research directions towards a comprehensive understanding of intra-cardiac flow and its clinical relevance. The knowledge could encourage more effective pre-operative planning and better outcomes for current clinical practices.

The concept of heterotopic implantation of transcatheter tricuspid valve is new and has shown promising results thus far. While the Reynolds shear stress values measured in the vicinity of this valve are relatively low, the values at some time points are higher than the threshold of platelet activation. Hence, in this study, we aim to reduce these values with an innovative stent design. It was shown that the Reynolds shear stress values measured were lower than those of valves made of generic stent design and the maximum Reynolds shear stress values in the vicinity of the valves was very low (∼10 dynes/cm

There has not been much progress in the development of transcatheter tricuspid valves to treat tricuspid regurgitation because of the difficulty in anchoring a stented valve onto the complex tricuspid annulus. Hence, the concept of heterotopic implantation of the transcatheter tricuspid valve onto the cavo-atrial junction was proposed. However, to date there has been no detailed in vitro investigation of the hemodynamic performance of this new device. The study utilises both 2-D and 3-D particle image velocimetry (PIV) to interrogate the flow patterns in the vicinity of the extra-cardiac tricuspid valves in an in vitro physiological flow loop, specifically at four measurement locations in the cavo-atrial anatomy. Comparison of the 2-D and 3-D PIV results revealed that accuracy of 2-D PIV would be acceptable at time point and at measurement locations where the velocity was mostly planar with minimal or low out-of-plane flow such as at the outlet of the superior vena cava valve at the point of valve closure. The results also showed that the RSS in the vicinity of the valves were relatively low (∼150 dynes/cm 2 ) with the exception of that in the leakage jet at the upstream of the valve. The leakage in the leaflets could be a result of the use of aortic valve leaflets which was more suited for the higher pressured environment of the left side of the heart. The stent design could also be customised for implantation in the vena cava. In summary, these issues could be eradicated with improvements to the leaflet and stent design which would enhance the haemodynamics of the post-implantation flow performance.

The expanded polytetrafluoroethylene (ePTFE) heart valve can serve as a viable option for prosthetic aortic valve. In this study, an ePTFE bi-leaflet valve design for aortic valve replacement (AVR) is presented, and the performance of the proposed valve was assessed numerically and experimentally. The valve was designed using CAE software. The dynamic behavior of the newly designed bi-leaflet valve under time-varying physiological pressure loading was first investigated by using commercial finite element code. Then, in-vitro tests were performed to validate the simulation and to assess the hemodynamic performance of the proposed design. A tri-leaflet ePTFE valve was tested in-vitro under the same conditions as a reference. The maximum leaflet coaptation area of the bi-leaflet valve during diastole was 216.3 mm2. When fully closed, no leakage gap was observed and the free edges of the molded valve formed S-shaped lines. The maximum Von Mises stress during a full cardiac cycle was 4.20 MPa. The dynamic performance of the bi-leaflet valve was validated by the in-vitro test under physiological aortic pressure pulse. The effective orifice area (EOA), mean pressure gradient, regurgitant volume, leakage volume and energy loss of the proposed valve were 3.14 cm2, 8.74 mmHg, 5.93 ml/beat, 1.55 ml/beat and 98.99 mJ, respectively. This study reports a novel bi-leaflet valve design for AVR. The performance of the proposed valve was numerically and experimentally assessed. Compared with the reference valve, the proposed design exhibited better structural and hemodynamic performances, which improved valve competency. Moreover, the performance of the bi-leaflet design is comparable to commercialized valves available on the market. The results of the present study provide a viable option for the future clinical applications. NMRC (Natl Medical Research Council, S’pore) Published version

Severe tricuspid regurgitation (TR) is life-threatening but is often undertreated. Many patients with severe TR are denied heart valve replacement surgery because their old age or comorbidities predispose them to a higher risk of surgical complications associated with open-heart surgery. With the advent of transcatheter technology, it is now possible to deliver the valve to the desired location without the need for open-heart surgery. However, presently, there is no commercially available transcatheter tricuspid valve. This may be due to the complex tricuspid valve anatomy, which lacks an anchorage zone for the percutaneous valves. In view of this drawback, we have recently developed and tested two percutaneous caval heart valves that are designed to deploy at the vena cava and atrium junction. The hemodynamic characteristics of these valves are tested in a mock circulatory system with patient-specific silicone atrium and vena cava, which emulates the physiological pressure and flow conditions at the right side of the human heart. Particle imaging velocimetry results showed that flow velocity and the associated Reynolds shear stress (RSS) and the turbulent kinetic energy (TKE) downstream of the valves increased after the implantation of the valves. A maximum flow velocity of 0.94 m/s was observed at the region downstream of the percutaneous valve at the superior vena cava (SVC). Maximum RSS value of 2076.1 dynes/cm(2) was observed downstream of the valve at the inferior vena cava during the deceleration phase while maximum TKE measured was 572.6 J/m(3) at the upstream of the valve in the SVC during the peak flow phase. While these values appear high, they are significantly lower than those reported in prosthetic mitral and aortic valves. Hence, caval stented valves can be potentially considered as a minimally invasive option to treat TR.