Valve Malfunction Research Articles

Status Monitoring System of Reciprocating Hydrogen Compressor Based on Hilbert−Huang Transform

ABSTRACTA reciprocating hydrogen compressor status monitoring system for predictive maintenance is developed based on HHT (Hilbert−Huang Transform) with multiple functions, strong applicability, and high accuracy to address the problem of difficulty in identifying fault signals and failure to provide advance warning before faults occur in the reciprocating hydrogen compressor state monitoring system. Design framework of monitoring system is confirmed, and function modules are designed based on LabView platform. HHT is applied to monitor the status of reciprocating hydrogen compressor based on LabView platform. A reciprocating hydrogen compressor is selected as research object, status monitoring analysis is carried out. Five working states of reciprocating hydrogen compressor are collected, which conclude normal state, filler malfunction, cross‐head malfunction, air valve malfunction, and piston rod malfunction. HHT is carried out for five signals, and results show that HHT marginal spectrum of five signals has different characteristics. Based on comparison results, precision of HHT ranges from 0.757 to 0.784, recall of HHT ranges from 0.738 to 0.766, F1‐score of HHT ranges from to 0.788 to 0.804, HHT has better performance than other two methods. Proposed monitoring system designed in this study provides a comprehensive and efficient online monitoring and data analysis solution for reciprocating hydrogen compressors, which can achieve fault prediction of reciprocating hydrogen compressor, reduce failure rate, and effectively improve the reliability of the compressor oil injection system.

Tackling the tubes of refractory Sturge–Weber syndrome with secondary glaucoma: A surgeon’s nightmare!

Hypotony with shallow anterior chamber (AC) post glaucoma surgery in Sturge–Weber syndrome (SWS) patients is commonly due to choroidal effusions. We report two cases of SWS patients having hypotony and shallow AC after Ahmed Glaucoma valve (AGV) implantation with no wound leak or choroidal effusion. Case 1 had persistent shallow AC, which was diagnosis of exclusion, as valve malfunction, a rare occurrence in AGV. Case 2 resolved after AC reformation with 1.8% sodium hyaluronate. Two cases describe the clinical approach and surgical management in patients of hypotony with shallow AC after AGV implantation in SWS patients.

Contributions of mechanical loading and hormonal changes to eccentric hypertrophy during volume overload: a Bayesian analysis using logic-based network models.

Primary mitral regurgitation (MR) is a pathology that alters mechanical loading on the left ventricle and induces a distinctive ventricular remodeling response known as eccentric hypertrophy. Drug therapies may alleviate symptoms, but only mitral valve repair can provide significant recovery of cardiac function and dimensions. However, 20% of patients still develop systolic dysfunction post-operatively despite being treated according to the current guidelines. Thus, better understanding of the hypertrophic process in the setting of ventricular volume overload (VO) is needed to improve and better personalize the management of MR. To address this knowledge gap, we employ a Bayesian approach to combine data from 70 studies on experimental volume overload in dogs and rats and use it to calibrate a logic-based network model of hypertrophic signaling in myocytes. The calibrated model suggests that growth in experimental VO is mostly driven by the neurohormonal response, with an initial increase in myocardial tissue stretch being compensated by subsequent remodeling fairly early in the time course of VO. This observation contrasts with a common perception that volume-overload hypertrophy is driven primarily by increased myocyte strain. The model suggests that Endothelin1 receptor activity plays a central role in driving hypertrophic responses and the activation of the fetal gene program. The model reproduces a number of responses to drug therapy not used in its calibration, and predicts that a combination of endothelin receptor antagonist and angiotensin receptor blockers would have the greatest potential to dampen cardiomyocyte hypertrophy and dysfunction in VO.

Outcomes after Endovascular Arch Repair in Patients with a Mechanical Aortic Valve: Results from a Multicentre Study

The aim of this study was to investigate outcomes after endovascular aortic arch repair in patients with a mechanical aortic valve where the valve needs to be crossed. An international, multicentre, retrospective observational study was undertaken including all consecutive patients who underwent endovascular arch repair with mechanical aortic valve crossing. From March 2020 to August 2023, 12 patients were included in the study (median age 55 years, interquartile range 45, 67 years; 58% male). Five patients (42%) had a genetically confirmed connective tissue disorder (CTD) and three more had a high clinical suspicion of CTD. Most patients had a bileaflet valve (11/12; 92%) and one patient had a monoleaflet one. All patients had previously undergone surgical ascending aortic repair. Technical success was 100% with successful completion of the procedure with no valve damage. Two deaths (17%) were observed in the first 30 days post-operatively with no signs of valve malfunction: one patient died of major stroke due to excessive wire and sheath manipulation in the arch; and another due to cardiac arrest of unknown cause, with no valve damage being detected in the autopsy. No intra-operative technical difficulties regarding valve cannulation were observed. During a median follow up of eight months, one patient died fifteen months after the procedure owing to non-aortic related causes, and four endoleaks were present on the latest computed tomography angiography, none type I or III. Endovascular aortic arch repair in a selected group of patients with a mechanical aortic valve treated in experienced, high volume aortic centres seems technically feasible and reasonably safe. These preliminary results underline the complexity of the procedure and should be validated by larger cohort studies. With careful patient selection and adequate physician experience, the presence of a mechanical aortic valve could potentially no longer pose a major contraindication for endovascular arch repair in the future.

Malposition of Central Venous Pressure Catheter as a Rare Cause of Tricuspid Valve Prosthesis Malfunction: A Case Report

Prosthetic valve malfunction is a hazardous clinical entity that needs early diagnosis and management. Hereby, we present a case of tricuspid valve (TV) malfunction due to interaction of central venous pressure (CVP) catheter with TV leaflets. Our case was a 38-year-old male who referred to our center with the diagnosis of TV malfunction. Confirming the diagnosis of TV malfunction, intravenous Heparin was initiated. Anticoagulation therapy was discontinued early due to the development of significant headache in the setting of subarachnoid hemorrhage. Due to contraindication of anticoagulation therapy, he underwent redo TV. On the 4th post-operative day, echocardiography examination illustrated significant increase in gradients of TV prosthesis. At this time, fluoroscopy depicted interaction of CVP catheter with TV leaflets due to its cardiac advancement resulted in fixed TV leaflets in semi-open position. By extraction of CVP catheter the TV gradients improved immediately. Malposition of CVP catheter or large CVP catheter could be considered as one of the rare causes of TV malfunction. Repositioning of CVP catheter brings dramatic improvement in this case.

Research and application of self-diagnosis and automatic intervention functions for turbine regulating valve malfunctions in nuclear power plants

Abstract The inlet regulating valve of the turbine is very important to the control of the turbine. If the control is abnormal, it will create some uncontrollable safety risks, which may cause the turbine to trip, even to over-speed. The study of the structure and control mode of the turbine regulating valve shows some defects in the design of the turbine regulating valve in a nuclear power plant. In this paper, through the analysis of the fault mode, the method of fault self-diagnosis is studied, verified, and improved so that it has perfect self-diagnosis and intervention means, improves the reliability of turbine valve control, and eliminates the hidden danger of tripping.

Extrinsic Positive End-Expiratory Pressure due to Failure of the Positive-Pressure Relief Valve Within the Scavenging System: A Case Report.

The anesthesia gas scavenging system (AGSS) removes waste gases from the anesthesia machine. Within the AGSS, safety features prevent excessive pressures from affecting ventilation. Although the literature contains reports describing failures of the AGSS, we found no reports of positive-pressure relief valve (PPRV) malfunctions. We encountered 2 cases of extrinsic positive end-expiratory pressure (PEEP) resulting from a malfunctioning PPRV. Both cases suffered delayed identification intraoperatively but patients did not experience postoperative complications. These cases highlight the importance of daily scavenger system prechecks, the potential physiologic implications of AGSS malfunctions, and the importance of preplanned contingencies for machine failure.

A data-driven online approach for detection and localization of forced oscillation in wind turbine integrated power system

This article introduces an innovative approach for online detection and localization of forced oscillation (FO) in power systems with significant integration of wind turbine generation (WTG). The synergistic combination of Multichannel Prony analysis with Periodogram and dissipating energy flow (DEF) approach is proposed in this paper to overcome the challenges inherent in detecting FO amidst the complexities introduced by WTG integration. An adaptive version of multichannel Prony analysis is proposed in this paper that dynamically estimates Prony’s system order via the recursive process. It estimates the frequency and damping ratio of all oscillatory modes, which is used to identify low damping modes that are potentially attributed to FO. Leveraging this information, the proposed method enhances both FO detection and source localization capabilities. The proposed method is verified on measurements taken from IEEE benchmark 4-machine, 11-bus system and 10-machine, 39-bus system with high wind energy penetration. Comprehensive testing demonstrates the proposed approach’s effectiveness across various FO scenarios, including governor valve malfunction, exciter malfunction, and cyclic loads. Furthermore, the methodology is evaluated under resonant conditions and scenarios involving the simultaneous identification of multiple disturbances.

Pilot study on high-resolution radiological methods for the analysis of cerebrospinal fluid (CSF) shunt valves

ObjectivesDespite their life-saving capabilities, cerebrospinal fluid (CSF) shunts exhibit high failure rates, with a large fraction of failures attributed to the regulating valve. Due to a lack of methods for the detailed analysis of valve malfunctions, failure mechanisms are not well understood, and valves often have to be surgically explanted on the mere suspicion of malfunction.The presented pilot study aims to demonstrate radiological methods for comprehensive analysis of CSF shunt valves, considering both the potential for failure analysis in design optimization, and for future clinical in-vivo application to reduce the number of required shunt revision surgeries. The proposed method could also be utilized to develop and support in situ repair methods (e.g. by lysis or ultrasound) of malfunctioning CSF shunt valves. Materials and methodsThe primary methods described are contrast-enhanced radiographic time series of CSF shunt valves, taken in a favorable projection geometry at low radiation dose, and the machine-learning-based diagnosis of CSF shunt valve obstructions. Complimentarily, we investigate CT-based methods capable of providing accurate ground truth for the training of such diagnostic tools. Using simulated test and training data, the performance of the machine-learning diagnostics in identifying and localizing obstructions within a shunt valve is evaluated regarding per-pixel sensitivity and specificity, the Dice similarity coefficient, and the false positive rate in the case of obstruction free test samples. ResultsContrast enhanced subtraction radiography allows high-resolution, time-resolved, low-dose analysis of fluid transport in CSF shunt valves. Complementarily, photon-counting micro-CT allows to investigate valve obstruction mechanisms in detail, and to generate valid ground truth for machine learning-based diagnostics.Machine-learning-based detection of valve obstructions in simulated radiographies shows promising results, with a per-pixel sensitivity >70%, per-pixel specificity >90%, a median Dice coefficient >0.8 and <10% false positives at a detection threshold of 0.5. ConclusionsThis ex-vivo study demonstrates obstruction detection in cerebro-spinal fluid shunt valves, combining radiological methods with machine learning under conditions compatible to future in-vivo application.Results indicate that high-resolution contrast-enhanced subtraction radiography, possibly including time-series data, combined with machine-learning image analysis, has the potential to strongly improve the diagnostics of CSF shunt valve failures. The presented method is in principle suitable for in-vivo application, considering both measurement geometry and radiological dose. Further research is needed to validate these results on real-world data and to refine the employed methods.In combination, the presented methods enable comprehensive analysis of valve failure mechanisms, paving the way for improved product development and clinical diagnostics of CSF shunt valves.

Risk assessment of solid desiccant dehydration package system using safety integrity level‐based safety instrumented system design approach

AbstractThe dehydration package system plays an important role in the stable process operation and production of high‐quality liquefied natural gas by removing water, which is essential for natural gas production. However, as this system operates under various conditions with chemicals, there are threats to safety from potential hazards within the system. Therefore, ensuring system safety can significantly impact the reliable operation of process plants. This study aims to assess the risk of the dehydration package system through the safety integrity level (SIL)‐based safety instrumented system (SIS) design approach as suggested in the International Electrotechnical Commission (IEC) 61,508/61511 standards. Fourteen major hazards requiring recommendations were identified for improving safety through the hazard and operability study (HAZOP). The three major hazards were valve malfunction and gas heater/cooler control failure. Twenty‐one safety instrumented functions (SIFs) in all study nodes were suggested as recommendations to improve safety. Using layers of protection analysis (LOPA), the SIL allocation of the 21 SIFs was performed reasonably with process risks and safeguards. The PDS method was adopted for SIS design and verification, with SIL analysis performed for all the SISs. The results showed that SISs of the dehydration package system satisfied the required SILs.

Evaluation of Risk Factors and Outcomes of Isolated Tricuspid Valve Replacement with a Conventional Surgical Approach: A Retrospective Cohort Study

Introduction. Tricuspid valve (TV) disease is substantially less common than mitral or aortic valve disease, and it is commonly missed due to the tolerability of stenosis or regurgitation. Adults seldom have primary tricuspid valve regurgitation, which is linked to rheumatic heart disease, infectious endocarditis, myxomatous valve disease, congenital heart disease, carcinoid syndrome, and/or infiltrative valvopathy. Materials and Methods. The authors examined the Valve Surgery Data Bank retrospectively to identify all patients who underwent TV replacement without concomitant surgeries between 2004 and 2014. In addition, the exclusion criteria suggested that all instances involving solitary valve repair were eliminated. Through visits or phone interviews, long-term follow-up was collected through the end of June 2022 in order to gather information on postoperative occurrences among the patients. The average follow-up time was 10.7 + 2.1 (5–15) years. Results. The overall survival rate was 90.9%. Survival rate was not significantly different between bioprostheses and mechanical ones (log rank <math xmlns="http://www.w3.org/1998/Math/MathML" id="M1"> <mi>p</mi> <mo>=</mo> <mn>0.05</mn> </math> ). The incidence of endocarditis and valvar thrombosis in short-term was higher in the mechanical group than in the biological group, but the frequency of valve malfunction and redo surgery was higher in the replacement group. We found a higher incidence of valvular thrombosis, GI bleeding, and myocardial infarction rate in mechanical valve complications compared to the bioprosthetic group regarding late complications.

Heart Failure Prediction using Gaussian Naïve Bayes Algorithm

Heart failure affects a minimum of 26 million individuals and its occurrence has been increasing day-by-day. Heart failure occurs when the heart cannot pump enough blood to meet the body's needs. This is caused due to various reasons such as coronary heart disease, heart valve malfunctioning, diabetes, anaemia etc. So, it is important to predict heart failure in its early stage to reduce the mortality rate. Cardiovascular disease is the major contributing factor for the prediction of heart failure. This research uses Gaussian Naïve Bayes technique which comes under supervised learning algorithm to predict heart failure. Gaussian Naïve Bayes algorithm treats each feature to be independent and each feature has equal importance in predicting heart failure. For the purpose of predicting heart failure, the mean and standard deviation of each column in a dataset is used. Different datasets are used for the implementation of heart failure prediction, and performance metrics are identified for each dataset. The findings of this study suggest that the Gaussian Naive Bayes algorithm can be a useful algorithm in predicting heart failure, and it has the potential to improve patient outcomes by facilitating early detection of heart failure. There are various metrics used for the performance analysis of the system such as, accuracy, recall, precision, confusion matrix and ROC curve. Finally, this study concludes by presenting the implementation of heart failure using Gaussian Naïve Bayes.

Acoustic monitoring of an aircraft auxiliary power unit

In this paper, the development and implementation of a novel approach for fault detection of an aircraft auxiliary power unit (APU) has been demonstrated. The developed approach aims to target the proactive identification of faults, in order to streamline the required maintenance and maximize the aircraft’s operational availability. The existing techniques rely heavily on the installation of multiple types of intrusive sensors throughout the APU and therefore present a limited potential for deployment on an actual aircraft due to space constraints, accessibility issues as well as associated development and certification requirements. To overcome these challenges, an innovative approach based on non-intrusive sensors i.e., microphones in conjunction with appropriate feature extraction, classification, and regression techniques, has been successfully demonstrated for online fault detection of an APU. The overall approach has been implemented and validated based on the experimental test data acquired from Cranfield University’s Boeing 737-400 aircraft, including the quantification of sensor location sensitivities on the efficacy of the acquired models. The findings of the overall analysis suggest that the acoustic-based models can accurately enable near real-time detection of faulty conditions i.e., Inlet Guide Vane malfunction, reduced mass flows through the Load Compressor and Bleed Valve malfunction, using only two microphones installed in the periphery of the APU. This study constitutes an enabling technology for robust, cost-effective, and efficient in-situ monitoring of an aircraft APU and potentially other associated thermal systems i.e., environmental control system, fuel system, and engines.

Prosthetic heart valve thrombosis - a headache for the heart team: A case report

Introduction. Prosthetic valve thrombosis is usually a subacute or chronic condition, although it may also present with a fresh thrombus. It occurs in two forms: obstructive and non-obstructive thrombosis. Case Report. We present a case of a female patient who underwent mitral valve replacement with mechanical prosthesis due to severe mitral stenosis. The postoperative course was uneventful and the patient was discharged on vitamin K antagonist therapy with international normalized ratio target 3.0. Five months later, the patient was admitted with severe shortness of breath and signs of acute heart failure. International normalized ratio at that moment was 2.3. Transthoracic echocardiography indicated severely raised gradient across the prosthetic valve and mechanical valve malfunction was suspected. Cinefluoroscopy showed that one of the prosthetic valve leaflets was completely immobile. Transesophageal echocardiography definitely confirmed thrombosis of the prosthetic valve with large multiple thrombi that completely fixed one leaflet in closed position, and partially limited the motion amplitude of the other leaflet. There were thrombi floating between the left ventricle and left atrium. Thrombectomy of the prosthetic valve was performed, which was sufficient for the complete restoration of the mechanical valve function. The vitamin K antagonist dosage was carefully up-titrated in order to reach and maintain the target international normalized ratio of 3.0. Conclusion. Prosthetic valve thrombosis is a serious and life-threatening condition that requires urgent management. Coordination and cooperation of the whole heart team is necessary for optimal choice of treatment, which primarily includes surgery or fibrinolysis.

OGC P49 Case report: Ivor Lewis oesophagectomy requiring one lung ventilation in a patient with a previous laryngectomy

Abstract Background A 68 year old patient with squamous cell carcinoma (SCC) of lower oesophagus (T3N0M0) presented for Ivor Lewis oesopphagectomy (ILO) following neoadjuvant chemoradiotherapy. Four years previously the patient had undergone total laryngectomy, radical right neck dissection with right pectoralis major flap and bilateral adjuvant radiotherapy for hypopharyngeal SCC (pT3N2bM0). A tracheal stoma was present with speaking valve in-situ. An ILO was planned requiring one lung ventilation (OLV) to facilitate surgical access. In our institution, OLV is routinely achieved via double lumen endotracheal tube (DLT), although endobronchial blocker through single lumen endotracheal tube or laryngeal mask airway and endobronchial intubation with a single lumen tube are potential options. Post laryngectomy the method used for lung isolation is limited and care must be taken not to traumatise the stoma site or surrounding tissue. Additionally, the angulation formed by the trachea and stoma mean a DLT is often not suitable while specific double lumen tracheostomy tubes may have too great a diameter for a small stoma. Surgically, close relations of the tumour to gastro-oesophageal junction, left diaphragmatic crus and descending thoracic aorta made suitability for resection uncertain, despite two negative staging laparoscopies. We describe the anaesthetic and surgical management of this interesting case. Methods General anaesthesia was delivered via an intravenous induction and maintenance was with sevoflurane. Airway management included bag mask ventilation with a neonatal facemask followed by placement of an 8mm reinforced endotracheal tube through the tracheal stoma. Prior to right thoracotomy a right sided 9Fr VivaSight endobronchial blocker (Ambu) was placed under direct vision using a single use Ambu aScope™ 4 Broncho Slim fibreoptic bronchoscope. OLV was successful using this method; SpO2 ≥96% (FiO2 0.6) and peak inspiratory pressure 18–20cmH2O-1. Analgesia comprised intrathecal morphine, right erector spinae plane local anaesthetic block and infusion catheter and morphine PCA. Abdominal phase was undertaken laparoscopically. The hiatus was noted to be fibrotic following chemoradiotherapy and a small capsular breach of the left lobe of liver occurred, controlled with Surgiflo (Ethicon). A right thoracotomy was performed through the 6th intercostal space. Right lung was deflated and surgical access was adequate. OrVil (Covidien – Medtronic) anastomosis was attempted but the anvil was unable to pass through the pharynx, therefore a purse string applicator was applied and OrVil staple used. The left pleura was also breached during dissection. One left and two right chest drains were placed. Results Postoperatively, analgesia was adequate and the patient did not require any cardiovascular or respiratory support. However, on first postoperative day it was noted that the speaking valve was not functioning causing significantly hoarse voice. A valve leak was detected and though hard to know the precise cause, it was assumed that it had become dislodged via either anaesthetic procedures, surgical handling or a combination. Despite some improvement in the symptoms over the first post-operative week, the patient also experienced airway soiling on commencing oral intake and after review by ENT a new valve was successfully sited and all symptoms resolved. Although a minor and easily rectifiable complication, the ‘loss of voice’ was very distressing for the patient. The patient had an otherwise uneventful postoperative course and was discharged home on day-11. Clinic review at six weeks revealed the patient had made a complete recovery and had resumed all normal activities. Histology showed scattered small foci of moderately differentiated SCC infiltrating the muscularis propria (stage ypT2). Longitudinal margins were clear of both dysplasia and malignancy. There was no evidence of lymphatic, venous or perineural invasion. One of 12 lymph nodes showed metastatic SCC. Adjuvant course of Nivolumab immunotherapy is currently planned. Conclusions We have presented an unusual case of previous laryngectomy plus requirement for OLV for ILO. The use of an endobronchial blocker via a reinforced endotracheal tube has been shown to be a successful airway management strategy. Speaking valve displacement and/or malfunction is a potential complication in such cases and should form part of preoperative counselling. Close liaison between surgical, anaesthetic and ENT teams is essential in the management of complex and unusual cases and, as we have demonstrated, strong teamwork leads to successful outcomes for patients.

P16.04.B Palliative CSF diversion in symptomatic leptomeningeal metastasis: a feasibility analysis of risks and benefits

Abstract Background Leptomeningeal metastasis (LM) represents a terminal condition in a subset of patients with primary extra-cranial malignancies. With improved survival rates under novel systemic therapies for extra-cranial primary tumors, the role of cerebrospinal fluid (CSF) diversion via ventriculo-peritoneal shunts (VP-shunt) for symptom control of hydrocephalic LM is becoming increasingly important. This study hence aimed to describe this patient cohort and weigh out benefits against adverse events of palliative VP-shunt placement. Material and Methods A single-center retrospective analysis of all consecutive adult patients with VP-shunt placement over a period of six years was performed and clinical data (primary disease, clinical presentation, CSF diagnostics, previous therapies) in addition to surgical data (shunt devices, surgeries, and complications) and survival data were collected. Results were compared to a ‘non-oncological’ shunt cohort and statistical analyses was performed. Results 38 patients with a median age of 53 (18-78) years (13 males, 25 females) underwent VP-Shunt placement. The most common underlying oncological conditions were breast cancer (n=21, 55%) and non-small cell lung cancer (NSCLC, n=11, 29%). The median time between primary tumor and LM diagnosis was 23 months (0 to 180 months). 14 patients (37%) presented with end-stage disease at primary tumor diagnosis, 25 (66%) patients had cranial metastases. Most patients presented with classical symptoms of intracranial hypertension and 11 patients (38%) had already received intrathecal treatment or radiotherapy before shunting. After shunting, symptom relief was achieved in 30 patients (79%) and 24 patients (63%) were eventually discharged home after surgery. Subsequently, 63% of the shunted patients underwent systemic or radiotherapy and 55% received intrathecal therapy. Revision surgery was performed for valve malfunctions and infections (n=3, 8% for either) or distal catheter malposition (n=2, 5%) but comparison with a ‘non-oncological’ shunt cohort showed no differences in complication rates. Median survival from shunting was 2.1 months (95% CI 0.5 to 3 months). Conclusion VP-shunt placement could relieve symptoms of intracranial hypertension secondary to LM of primary solid tumors without a higher risk of shunt complications compared to non-oncological patients, with many LM patients persuing further oncologic therapy. However, decision-making regarding VP-shunt placement in LM patients still retains a palliative nature.

Lessons Learned From Intermittent Dysfunction of Mechanical Heart Valve.

Background:Intermittent malfunction is a rare but potentially serious complication of prosthetic heart valve replacement. This study aimed to describe the clinical features and etiologic causes of patients with intermittent mechanical prosthetic heart valve dysfunction.Methods:Between 2010 and 2021, 16 patients who were evaluated in the echocardiography laboratory of Koşuyolu Training and Research Hospital with the diagnosis of intermittent malfunction of prosthetic valves were included in the study.Results:The evaluated patients consisted of 12 bi-leaflet mitral valve replacements and 2 mono-leaflet mitral valve replacements. The underlying causes of intermittent malfunction were classified as follows: residual chord (n = 4), obstructive thrombus (n = 2), non-obstructive thrombus (n = 2), vegetation (n = 2), pannus and obstructive thrombus coexistence (n = 1), and solely pannus (n = 1). One of the patients with mono-leaflet mitral valve replacements had pannus and obstructive thrombus. In the other patient with mono-leaflet mitral valve replacement, a stuck valve was observed in 1 of 12 beats secondary to arrhythmia. There were also 2 patients with aortic valve replacements. One patient had moderate aortic regurgitation due to prominent calcification and the other had moderate obstruction due to pannus. In the patient with pannus, a stuck leaflet was observed in 1 of 6 beats and moderate aortic regurgitation arose in 1 of 2 beats in the patient with calcification.Conclusions:The intermittent stuck valve may have catastrophic outcomes. When making a treatment decision in these patients, assessing the degree of regurgitation or stenosis is essential. In particular, the frequency of entrapment should be taken into consideration when deciding the optimal therapy for intermittent prosthetic heart valve dysfunction.

Effects of physical exercise to treat ulcerated and non-ulcerated chronic venous insufficiency: systematic review

The chronic venous insufficiency (CVI) is defined as alteration on the venous flow, caused by malfunction of the venous valves, obstruction of vases and weakness of the sural triceps muscle. The physical exercise is being studied as a form of treatment of this disease to be considered of low cost and easy access. Objective: The aim was to analyze the effects of different types of physical exercise in the venous hemodynamics, muscular function and in the quality of life of individuals with CVI ulcerated and non-ulcerated. Method: The articles were obtained by a research on six data bases. were included articles in which the exercise was a form of intervention in patients with CVI. Results: Were founded 2.297 clinical trials randomized and non-randomized, nine were included. These studies applied different protocols of exercise, that were an association of mobility, strength, force, and aerobic exercises. This association showed improvement in the different clinical conditions of the CVI, and a positive impact their quality of life. Conclusion: The physical exercise is benefic to patients with CVI, being able to reduce symptoms, increase quality of life and prevent the progression of the diseases, could reduce the cost to the health systems.

Determination of lower break-out of the boom on wells equipped plunger pump

Development of fields at a late or final stage of exploitation of the Ural-Volga region is carried out mainly with the use of downhole sucker rod pumping units. The most typical failures for these installations are rods breaks and breaks and pump valve malfunctions. Methods for eliminating these accidents vary significantly: a break or a breakaway of the rods involves lifting the downhole equipment, and the "sticking" of the shut-off element of the pump valve assembly is eliminated by the "resuscitation" of the downhole equipment (flushing with water, hot oil or solvent). An error in recognizing a malfunction leads to incorrect planning of work to restore the operability of downhole equipment, and, as a result, to economic losses.The cause of the downhole equipment malfunctions of the sucker rod pumping units is usually determined by analyzing the dynamogram. However, in many cases dynamometer charts don't distinguish between the bottom flap of the rods and the failure of the sucker rod pump valves. In the article, a method of prompt determination of rod breakage and breakaway in a well is considered, which consists in creating an electrical circuit "rod string - tubing string" and monitoring its integrity. To determine the type of malfunction, the synchronization unit via the electromagnetic channel measures the resistance of the system on the dielectric insert. In case of break-off of rods, the electrical resistance of the "tubing-pump-rod string" circuit will be much higher (more than 2 ohms) than in the absence of this failure (0...2 ohms).

Introduction of a Novel, Continuous, Noninvasive Estimation of Intracranial Pressure and Cerebral Perfusion Pressure Based on Tympanic Membrane Temperature

Hydrocephalus is a common but potentially life-threatening condition. However, valve malfunction makes further diagnosis difficult. Thus, we tried to develop a noninvasive method to detect the hydrocephalus intracranial pressure (ICP) during routine follow-up. In group I, the patient was recruited because a spinal tap test was necessary for either disease diagnosis or treatment. In group II, patients were diagnosed with high ICP hydrocephalus and received shunt surgery. The tympanic membrane temperatures (TMTs) were recorded and plotted against the spinal tap pressure (STP) and shunt valve pressures. All patients in group I showed an above-normal STP (from 180 to 400 mm H2O). The STP presents with an inverted U-shaped curve when it is plotted against TMT (R2= 0.9). When the STP was 286.1 mm H2O, the TMT approached its peak value, which was 38.61°C (101.5°F). However, when ICP was in the normal range (50-200 mm H2O), the TMT correlated with ICP in a linear regression model (R2= 0.69; P < 0.001). In addition, the cerebral perfusion pressure (CPP) was calculated and plotted against TMT. The TMT-CPP was also shown as a parabola (R2= 0.74). Based on the TMT-ICP algorithm, we invented a noninvasive ICP monitor system, which performs in a manner comparable to the Codman ICP Transducer (R2= 0.9; P < 0.01). Both Y-Jiang TMT-ICP and TMT-CPP algorithms are useful to monitor the shunt outcomes and identify potential shunt failure. More importantly, these algorithms open the possibility for the rational acquisition of ICP and CPP noninvasively.