Early Prosthetic Valve Endocarditis with Mycobacterium Tuberculosis after Mitral Valve Replacement: A Case Report

Background: Tuberculous endocarditis is a rare but serious complication of heart valve replacement surgery. We report the case of a 24-year-old patient, who presented with tuberculous endocarditis after mechanical mitral valve replacement, with a favorable clinical course following anti-tuberculosis treatment. Case Presentation: We report a 24-year-old male patient, admitted to the cardiac surgery department of the Fann Hospital (Dakar, Senegal), for the management of severe mixed (rheumatic and endocarditic) mitral insufficiency with associated tricuspid insufficiency. He had a history of recurrent angina and polyarthralgia in childhood, was hospitalized several times for refractory global cardiac decompensation, and for a suspected infective endocarditis a month before his admission. On admission, the clinical examination revealed signs suggestive of mitral and tricuspid insufficiency. Transthoracic echocardiography revealed severe post-endocarditic mitral insufficiency with A3 amputation, highly mobile 15 mm vegetations on the free edge of the large valve, moderate tricuspid insufficiency, and severe pulmonary artery hypertension. Mechanical mitral valve replacement and tricuspid valve annuloplasty using autologous pericardial strip were performed via median sternotomy. After ten days, the patient presented with global cardiac decompensation associated with a clinico-biological infectious syndrome, and tans-oesophageal echography revealed an abscess at the sinotubular junction, communicating with the aorta. A thoraco-abdomino-pelvic CT scan was done, which revealed a bilateral alveolar-interstitial syndrome with mediastinal lymphadenopathy. Anti-tuberculosis treatment with RHZE was initiated for 06 months. The clinical course was favorable. Conclusion: Tuberculous endocarditis in prostheses is a serious complication of heart valve replacement surgery, which may evolve favorably under medical treatment.

Native and prosthetic septic arthritis in a university hospital in Saudi Arabia:A retrospective study

BACKGROUND Septic arthritis,whether native or prosthetic,poses a significant challenge in clinical practice due to its potentially devastating consequences.Despite its clinical importance,there remains a dearth of comprehensive studies and standardized diagnostic criteria,particularly in the Kingdom of Saudi Arabia.AIM To investigate the epidemiology,microbiological profiles,and clinical characteristics of native and prosthetic septic joints in the Saudi Arabian population.METHODS Medical records of patients diagnosed with septic arthritis between January 1,2015,and December 31,2022,were retrospectively reviewed.Data regarding patient demographics,clinical presentation,microbiological cultures,treatment modalities,and outcomes were analyzed.RESULTS In a retrospective review of 52 cases of septic arthritis,a balanced gender distribution was observed(1:1 ratio),with the knee being the most commonly affected joint(80.8%).Methicillin-resistant Staphylococcus aureus predominated in native joints(24.2%),while Brucella spp.was more prevalent in prosthetic joints(21.1%).Joint preservation was achieved in most cases(84.6%),with no significant difference in clinical features between native and prosthetic joints.However,certain comorbidities were more common in native joint cases,including renal impairment(P=0.002),hemodialysis(P=0.004),heart disease(P=0.013),and chronic liver disease(P=0.048).At the same time,osteoarthritis was more prevalent in prosthetic joint cases(P=0.013).Vancomycin was the most frequently used antibiotic(26.9%),and most patients received antibiotics before joint aspiration(57.7%).Surgical intervention,predominantly arthrotomy,was required in most cases(32.7%).Notably,a significant association was found between joint type and mortality(odds ratio=0.587,P=0.048),as well as the Charlson comorbidity index and mortality(P=0.001).CONCLUSION This study highlighted distinctive microbiological profiles and etiological factors in septic arthritis cases in the Saudi Arabian population.

Dynamic Analysis and Performance Verification of a Novel Hip Prosthetic Mechanism

To assist an amputee in regaining his or her daily quality of life,based on analysis of the motion characteristics of the human hip,a 2-UPR/URR parallel mechanism with a passive limb was designed.The inverse kinematics of this mechanism was analyzed based on a closed-loop vector method.The constrained Jacobian matrix and kinematic Jacobian matrix of each limb were then analyzed,and a 6×6 fully Jacobian matrix was constructed.Based on this,kinematic performances were analyzed and summarized.Finally,the dynamic model of the mechanism was constructed based on the virtual work principle,and its theoretical solution was compared with the numerical results,which were obtained in a simulation environment.Results showed that the prosthetic mechanism had a larger rotating workspace and better mechanical performance,which accorded a range of motion and bearing capacity similar to that of the human hip in multiple gait modes.Moreover,the validity of the dynamic model and inverse kinematics were verified by comparing the theoretical and simulation results.Furthermore,with flexion and extension,the torque change in the hip prosthetic mechanism was similar to that of the human hip,which demonstrated the feasibility of the hip prosthetic mechanism and its good dynamic performance.

Obstructive shock secondary to fungal prosthetic aortic valve endocarditis

Dear editor,Fungal endocarditis is a rare disease with a poor prognosis,suboptimal diagnostic tools responsible for long diagnostic delays in most cases,and poorly defined activity of most antifungal agents in endocarditis.^([1])The burden of diagnosis still lies with clinicians:they need a

Left atrial thrombosis in an anticoagulated patient after bioprosthetic valve replacement:Report of a case

We present the case of a 74 year old woman suffering from severe mitral valve incompetence and rapid atrial fibrillation. After an appropriate vitamin K antagonist(VKA) therapy, the patient underwent mitral valve replacement by bioprosthesis. Then, the patient was rehospitalized for jaundice. Suspecting hepatotoxicity, VKA was discontinued and fondaparinux was started. During this treatment, the patient developed a symptomatic atrial thrombus. After exclusion of a hepatic disease, VKA was re-established with hemodynamic and liver enzymes normalization and atrial thrombus resolution. Caution has to be used when considering fondaparinux as an alternative strategy to VKA in patients with multiple thrombotic risk factors.

Molecularly specific detection of bacterial lipoteichoic acid for diagnosis of prosthetic joint infection of the bone

Discriminating sterile inflammation from infection, especially in cases of aseptic loosening versus an actual prosthetic joint infection, is challenging and has significant treatment implications. Our goal was to evaluate a novel human monoclonal antibody（mAb） probe directed against the Gram-positive bacterial surface molecule lipoteichoic acid（LTA）. Specificity and affinity were assessed in vitro. We then radiolabeled the anti-LTA mAb and evaluated its effectiveness as a diagnostic imaging tool for detecting infection via immuno PET imaging in an in vivo mouse model of prosthetic joint infection（PJI）. In vitro and ex vivo binding of the anti-LTA mAb to pathogenic bacteria was measured with Octet, ELISA, and flow cytometry. The in vivo PJI mouse model was assessed using traditional imaging modalities, including positron emission tomography（PET） with [^（18）F]FDG and [^（18）F]Na F as well as X-ray computed tomography（CT）, before being evaluated with the zirconium-89-labeled antibody specific for LTA（[^（89）Zr]SAC55）.The anti-LTA mAb exhibited specific binding in vitro to LTA-expressing bacteria. Results from imaging showed that our model could reliably simulate infection at the surgical site by bioluminescent imaging, conventional PET tracer imaging, and bone morphological changes by CT. One day following injection of both the radiolabeled anti-LTA and isotype control antibodies, the anti-LTA antibody demonstrated significantly greater（P 〈 0.05） uptake at S. aureus-infected prosthesis sites over either the same antibody at sterile prosthesis sites or of control non-specific antibody at infected prosthesis sites. Taken together, the radiolabeled anti-LTA mAb, [^（89）Zr]SAC55, may serve as a valuable diagnostic molecular imaging probe to help distinguish between sterile inflammation and infection in the setting of PJI. Future studies are needed to determine whether these findings will translate to human PJI.

Non-albicans Candida prosthetic joint infections: A systematic review of treatment

BACKGROUND Non-albicans Candida prosthetic joint infections (PJIs) are rare. Optimal treatment involves a two-stage revision surgery in combination with an antifungal agent. However, no clear guidelines have been developed regarding the agent or treatment duration. Hence, a broad range of antifungal and surgical treatments have been reported so far. AIM To clarify treatment of non-albicans Candida PJIs. METHODS A literature review of all existing non-albicans Candida PJIs cases through April 2018 was conducted. Information was extracted about demographics, comorbidities, responsible species, duration and type of antifungal treatment, type of surgical treatment, time between initial arthroplasty and symptom onset, time between symptom onset and definite diagnosis, outcome of the infection and follow-up. RESULTS A total of 83 cases, with a mean age of 66.3 years, were located. The causative yeast isolated in most cases was C. parapsilosis (45 cases;54.2%), followed by C. glabrata (18 cases;21.7%). The mean Charlson comorbidity index was 4.4 ± 1.5. The mean time from arthropalsty to symptom onset was 27.2 ± 43 mo, while the mean time from symptom onset to culture-confirmed diagnosis was 7.5 ± 12.5 mo. A two stage revision arthroplasty (TSRA), when compared to one stage revision arthroplasty, had a higher success rate (96% vs 73%, P = 0.023). Fluconazole was the preferred antifungal agent (59;71%), followed by amphotericin B (41;49.4%). CONCLUSION The combination of TSRA and administration of prolonged antifungal therapy after initial resection arthroplasty is suggested on the basis of limited data.

A novel grasping force control strategy for multi-fingered prosthetic hand

A grasping force control strategy is proposed in order to complete various free manipulations by using anthropomorphic prosthetic hand. The position-based impedance control and force-tracking impedance control are used in free and constraint spaces, respectively. The fuzzy observer is adopted in transition in order to switch control mode. Two control modes use one position-based impedance controller. In order to achieve grasping force track, reference force is added to the impedance controller in the constraint space. Trajectory tracking in free space and torque tracking in constrained space are realized, and reliability of mode switch and stability of system are achieved. An adaptive sliding mode friction compensation method is proposed. This method makes use of terminal sliding mode idea to design sliding mode function, which makes the tracking error converge to zero in finite time and avoids the problem of conventional sliding surface that tracking error cannot converge to zero. Based on the characteristic of the exponential form friction, the sliding mode control law including the estimation of friction parameter is obtained through terminal sliding mode idea, and the online parameter update laws are obtained based on Lyapunov stability theorem. The experiments on the HIT Prosthetic Hand IV are carried out to evaluate the grasping force control strategy, and the experiment results verify the effectiveness of this control strategy.

HIT prosthetic hand based on tendon-driven mechanism

An underactuated finger structure actuated by tendon-driven system is presented.Kinematics and static analysis of the finger is done,and the results indicate that the prosthetic finger structure is effective and feasible.Based on the design of finger,a prosthetic hand is designed.The hand is composed of 5 independent fingers and it looks more like humanoid.Its size is about 85% of an adult's hand and weights about 350 g.Except the thumb finger,each finger is actuated by one DC motor,gear head and a tendon,and has three curling/extension joints.The thumb finger which is different from other existing prostheses is a novel design scheme.The thumb finger has four joints including three curling/extension joints and a joint which is used to realize the motion of the thumb related to the palm,and these joints are also driven by one DC motor,harmonic drive and a tendon.The underactuation and adaptive curling/extension motion of the finger are realized by joint torsion springs.A high-powered chip of digital signal processing(DSP)is the main part of the electrical system which is used for the motors control,data collection,communication with external controlling source,and so on.To improve the reliability of the hand,structures and sensors are designed and made as simply as possible.The hand has strong manipulation capabilities that have been verified by finger motion and grasping tests and it can satisfy the daily operational needs and psychological needs of deformities.

Technetium-99m-labeled annexin V imaging for detecting prosthetic joint infection in a rabbit model

Accurate and timely diagnosis of prosthetic joint infection is essential to initiate early treatment and achieve a favorable outcome. In this study, we used a rabbit model to assess the feasibility of technetium-99m-labeled annexin V for detecting prosthetic joint infection. Right knee arthroplasty was performed on 24 New Zealand rabbits. After surgery, methicillin-susceptible Staphylococcus aureus was intra-articularly injected to create a model of prosthetic joint infection （the infected group, n = 12）. Rabbits in the control group were injected with sterile saline （n= 12）. Seven and 21 days after surgery, technetium-99m-labeled annexin V imaging was per- formed in 6 rabbits of each group. Images were acquired 1 and 4 hours after injection of technetium-99m- labeled annexin V （150 MBq）. The operated-to-normal-knee activity ratios were calculated for quantitative ana- lysis. Seven days after surgery, increased technetium-99m-labeled annexin V uptake was observed in all cases. However, at 21 days a notable decrease was found in the control group, but not in the infected group. The operated-to-normal-knee activity ratios of the infected group were 1.84 ±0.29 in the early phase and 2.19 ±0.34 in the delay phase, both of which were significantly higher than those of the control group （P=0.03 and P=0.02）. The receiver operator characteristic curve analysis showed that the operated-to-normal-knee activity ratios of the delay phase at 21 days was the best indicator, with an accuracy of 80%. In conclusion, technetium- 99m-labeled annexin V imaging could effectively distinguish an infected prosthetic joint from an uninfected prosthetic joint in a rabbit model.

Horseshoe thrombus in a patient with mechanical prosthetic mitral valve: A case report and review of literature

Patients with prosthetic cardiac valves are at high risk for thromboembolic complications and need life long anticoagulation with warfarin, which can be associated with variable dose requirements and fluctuating level of systemic anticoagulation and may predispose to thromboembolic and or hemorrhagic complications. Prosthetic cardiac valve thrombosis is associated with high morbidity and mortality. A high index of suspicion is essential for prompt diagnosis. Transthoracic echocardiography, and if required transesophageal echocardiography are the main diagnostic imaging modalities. Medically stable patients can be managed with thrombolytic therapy and anticoagulation, while some patients may require surgical thrombectomy or valve replacement. We present a case report of a patient with prosthetic mitral valve and an unusually large left atrial thrombus with both thromboembolic and hemorrhagic complications.

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

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

Development of an underactuated prosthetic hand with the step motor

We present the development of a novel prosthetic hand based on the underactuated mechanism. The aim is focused on increasing its dexterity while keeping the same dimension and weight of a traditional prosthetic device. The hybrid step motor is used as the actuator, which enables the finger to keep enough high contact torque on the grasped object with less energy consumption provided by the holding torque. The grasping force of the finger is estimated from the base joint torque, and the adoption of impedance control has provided compliance in the grasping. Also a parallel observer is used to switch over between the impedance control and the torque holding mode. The experimental results show the effectiveness of the design and control strategy.

INFLUENCE OF MIMIC CARDIAC RATE ON HYDRODYNAMICS OF DIFFERENT MECHANICAL PROSTHETIC CARDIAC VALVES IN VITRO

Objective To assess the influence of mimic cardiac rate on hydrodynamics of different mechanical prosthetic cardiac valves. Methods US-made CarboMedics bileaflet valve, China-made Jiuling bileaflet valve and C-L tilting disc valve were tested via a pulsatile flow simulator in the aortic position. Testing conditions were set at mimic cardiac rates of 55 bpm, 75 bpm, 100 bpm with a constant mimic cardiac output of 4 L/min. The mean pressure differences (ΔP), leakage volumes (LEV) and closing volumes (CLV) across each valve, and effective orifice areas (EOA) were analyzed. Results Within physiological range, ΔP, LEV, and CLV decreased as mimic cardiac rate increased, with a large extent of variance. EOA increased along with an increase in mimic cardiac rate. It was a different response in terms of cardiac rate alteration for different types of mechanical prosthetic cardiac valves. Conclusion Mimic cardiac rate change affects hydrodynamics of mechanical prosthetic cardiac valves. Within physiological range, the hydrodynamic of prosthetic bileaflet valve is better than that of tilting disc valve.

Prosthetic joint infections-a clinico-microbiological perspective: Review article

Prosthetic joint infections(PJIs),although not very common,currently pose a very significant threat since they are associated with severe complications,high morbidity rates and substantial costs.PJIs are most commonly caused by Staphylococcus aureus and coagulase-negative staphylococci.The diagnosis of implant-associated infections is very challenging since no single routinely used laboratory or clinical test has been shown to demonstrate adequate results with respect to sensitivity,specificity and accuracy.In most cases,a sum of clinical signs and symptoms,histopathology,blood tests,radiography,bone scans and microbiological testing is considered to arrive at an accurate diagnosis.Treatment of PJIs is also very difficult since most of the infections are caused by biofilm-producing microorganisms which are significantly more resistant to the hosts natural defense mechanisms and antibiotic treatment.For successful management,a combination of both antibiotic and surgical treatment is most often required,and early diagnosis is of the utmost importance.Thus,a multidisciplinary approach is potentially the best option in dealing with PJI,and should include the involvement of microbiologists,orthopedic specialists,clinicians,pathologists and radiologists in order to improve decision-making processes and ensure overall success.The following review aims at briefly outlining the microbiology,diagnostic and treatment options,and preventive measures associated with such infections.

Risk of methicillin-resistant staphylococcus aureus prosthetic joint infection in elective total hip and knee arthroplasty following eradication therapy

BACKGROUND Prosthetic joint infection(PJI)is a devastating complication requiring prolonged treatment and multiple operations,leading to significant morbidity for the patient.Patients are routinely tested for methicillin-resistant staphylococcus aureus(MRSA)colonisation.MRSA positive patients are given eradication therapy.We hypothesise that patients who are MRSA positive pre-operatively,have increased risk of developing PJI.AIM To identify deep wound infection(PJI)rates in patients who are colonised MRSA positive compared with those who are not colonised;and long term clinical and radiological outcomes.METHODS All patients who underwent total hip and knee replacements(THR/TKR)between December 2009 and December 2019 were identified.Patients who were also identified as being MRSA positive at pre-operative assessment were then selected.Confirmation of prescribing eradication treatment was recorded.Patient records,including consultation letters,operation notes and microbiology results were reviewed retrospectively.Comparison of outcomes for each MRSA positive patient was made with 2 MRSA negative patients undergoing the same operation of a similar age by the same consultant.RESULTS Screening identified 42 knee and 32 hip arthroplasty patients as MRSA positive,84 MRSA negative knee and 64 hip patients were reviewed.Patients were matched with medical co-morbidities in each group.Mean follow up was 5 years.PJI was identified in 4/32(12.5%)of THR MRSA positive and 3/42(7%)of TKR patients.All patients had PJI within one year of surgery.CONCLUSION MRSA positive patients are given eradication therapy routinely.However,no confirmation of eradication is sought.Patients who have MRSA colonisation preoperatively,in our study had a significantly increased risk of PJI,when compared to negative patients.We would recommend establishing true eradication after treatment prior to arthroplasty.

Status of Oral Prosthetic Rehabilitation of Edentulism at the University Clinics of Kinshasa (CUK), DR Congo

Objective: The present work aimed to identify the most common edentulousness and prosthesis type (prosthetic treatment), to improve the management in oral prosthetic rehabilitation in DR Congo. Material and Methods: It was a documentary, longitudinal, and retrospective study of the medical records of edentulous patients admitted to the prosthetic service of the Dental Department/Kinshasa University from January 1983 to December 2020. Age, sex, cause of teeth loss, and prosthetic treatment (partial removable prosthesis, complete removable prosthesis) were evaluated. The Chare square test was performed to compare significant differences between the variables and the P-value < 0.05 was set as significant. Results: One thousand six hundred and ninety patients in that 901 were men (47 ± 16 years) and 789 women (42 ± 15 years) had undergone prosthetic treatment. One thousand eight hundred and forty-four edentulous teeth were viewed according to the Kennedy classification. Kennedy class 1 was the most predominant (61.4%) followed by Kennedy class 3 (24.8%). Two thousand one hundred and ninety-one prostheses were performed. The removable partial prosthesis with plate (acrylic resin) was the most performed (78.8%;n = 1727) and followed by the joint (17.4%;n = 384). Dental caries (52.6%) and periodontitis (36.4%) were the main causes of these edentulous teeth. Conclusion: The present study showed that edentulism is becoming a concern for the implementation of a real oral health policy.

A five-fingered underactuated prosthetic hand:hardware and its control scheme

A five-fingered underactuated prosthetic hand controlled by surface EMG (electromyographic) signals is presented in this paper. The prosthetic hand was designed with simplicity, lightweight and dexterity on the requirement of anthropomorphic hands. Underactuated self-adaptive theory was adopted to decrease the number of motors and weight. The control part of the prosthetic hand was based on a surface EMG motion pattern classifier which combines LM-based (Levenberg-Marquardt) neural network with the parametric AR (autoregressive) model. This motion pattern classifier can successfully identify the flexions of the thumb, the index finger and the middle finger by measuring the surface EMG signals through two electrodes mounted on the flexor digitorum profundus and flexor pollicis longus. Furthermore, via continuously controlling a single finger's motion, the five-fingered underactuated prosthetic hand can achieve more prehensile postures such as power grasp, centralized grip, fingertip grasp, cylindrical grasp, etc. The experimental results show that the classifier has a great potential application to the control of bionic man-machine systems because of its fast learning speed, high recognition capability and strong robustness.

Development of Multi-Fingered Prosthetic Hand Using Shape Memory Alloy Type Artificial Muscle

A new prosthetic hand with a fixed thumb and four fingers actuated by Shape Memory Alloy （SMA） type artificial muscle has been developed in this paper. Different from typical geared motor, SMA actuator is lightweight and silent, however shows a little short stroke and small attracting force per each unit. In order to achieve enough output force and motion range of each finger, multiple SMA type artificial muscles with special device which facilitates enough length are equipped in the hand. The fundamental properties of the SMA type artificial muscle including output force and electrical response were determined experimentally and considered for the design of hand mechanism. Besides, the structure of each finger and whole system has been designed based on observation of human hand. The electrical hardware to control multiple shape memory alloy type artificial muscles has been also developed. Finally, the usefulness of the prosthetic hand has been investigated through experiments for grasping several types of objects.

Multimodality imaging in the diagnosis and management of prosthetic valve endocarditis:A contemporary narrative review

Infective endocarditis is one of the leading life-threatening infections around the world.With the exponential growth in the field of transcatheter interventions and advances in specialized surgical techniques,the number of prosthetic valves and cardiac implantable devices has significantly increased.This has led to a steep rise in the number of cases of prosthetic valve endocarditis(PVE)comprising up to 30%of all cases.Clinical guidelines rely on the use of the modified Duke criteria;however,the diagnostic sensitivity of the modified Duke criteria is reduced in the context of PVE.This is in part attributed to prosthesis related artifact which greatly affects the ability of echocardiography to detect early infective changes related to PVE in certain cases.There has been increasing recognition of the roles of complementary imaging modalities and updates in international society recommendations.Prompt diagnosis and treatment can prevent the devastating consequences of this condition.Imaging modalities such as cardiac computed tomography and 18-fluorodeoxyglucose positron emission tomography/computed tomography are diagnostic tools that provide a complementary role to echocardiography in aiding diagnosis,pre-operative planning,and treatment decisionmaking process in these challenging cases.Understanding the strengths and limitations of these adjuvant imaging modalities is crucial for the implementation of appropriate imaging modalities in clinical practice.