Patch Repair Research Articles

Tetralogy of Fallot transannular patch repair with or without monocusp valve reconstruction

Tetralogy of Fallot transannular patch repair with or without monocusp valve reconstruction

Spall Repair Patch Health Monitoring System Using BIM and IoT

Spall Repair Patch Health Monitoring System Using BIM and IoT

Repair of damaged composite materials after patching experimental investigation of influencing factors

In this study, an experimental study was conducted on the reuse of composite materials after they were damaged. Since composite materials are difficult to recycle and reuse, their presence as waste in the environment is an ecological problem. Therefore, it is more convenient and economical to disassemble the damaged parts and make repairs instead of using new materials. In addition, due to the high cost of these materials, their repairs are preferred. For this study, after glass and carbon fiber-reinforced layer composite plates/sheets were produced, damage in the form of a 10 mm round hole was created. These damaged areas were made ready for repair by applying mechanical processes around them. For repair procedures, different adhesives and patches were applied under appropriate laboratory conditions, and the damaged samples were repaired. Various factors were taken into consideration during the repairs. These factors included the W/D ratio, adhesive thickness, adhesive type, fiber reinforcement angle change in the patch and base material (0, 15, 30, 45), patch thickness, and patch geometry. As a result, different destructive tests were applied to these repaired samples and thus the damage loads of each repair were determined. The results of these damage loads obtained for different factors were compared with the results of the current study in the literature and displayed in plots.

Comparative Study of Collagen Density, Fibroblast, and Neovascularization in Tracheal Defect Reconstruction with Primary Repair and External Oblique Muscle Aponeurosis Patch (A Novel Study with New Zealand Rabbit)

Background: The lack of ideal materials and the high incidence of complications make tracheal defect reconstruction challenging. The use of aponeurosis as a surgical patch and flap in reconstruction is not uncommon, but no studies had been conducted to analyse its use in tracheal defect reconstruction, though its effectivity in wound healing was significant in reconstruction of other organs. Objective: This study aims to compare collagen density, fibroblast expression, and neovascularization in tracheal defect reconstruction using primary suture and using external oblique muscle aponeurosis patch. Methods: This randomized control trial is a laboratory experimental study using male New Zealand white rabbits. Randomization was carried out with permuted block randomization into a control group (primary suture) and a treatment group (reconstruction with external oblique muscle aponeurosis patch). Mascroscopic and histopathological assessments were carried out 14 days after surgery. Results: We got homogeneous samples in both groups (9 samples each) in terms of age (p = 0.763), weight before procedure (p = 0.347), and weight after procedure (p = 0.536). Macroscopically, no wound dehiscence, pus, or inflammation at the surgical site in either the control or treatment groups. Histopathological analysis showed that there were no differences in collagen density (p = 1.00), fibroblast expression (p = 0.414), and neovascularization (p = 0.558) between the two groups. Conclusion: It can be concluded that there are no differences in collagen density, fibroblast expression, and neovascularization in New Zealand rabbits with tracheal defect using primary suture and using external oblique muscle aponeurosis patch

Optimization of Composite Material Repair Patch Shape Based on Strength Analysis

With the increasing use of composite materials in aircraft structures and the extension of their service life, the selection of repair patch shapes for composite material damage repair has become a significant engineering concern. The ultimate strength of the repaired structure is among the main evaluation criteria for selecting optimal patch shapes. In this study, strength analysis is conducted along with the use of the Digital Image Correlation (DIC) method to assess the quality of the repaired components, making the evaluation method more rational. Early studies often focused on simplified models, which diverged significantly from the practicalities of maintenance engineering in civil aviation. Therefore, it is essential to research full-scale composite material repair patches, as this will provide a more reliable basis for the optimal selection of patch shapes in composite material maintenance engineering for civil aircraft.

Self-reported respiratory and gastrointestinal outcomes in children with isolated congenital diaphragmatic hernia: A prospective multicentre study.

To evaluate medium-term self-reported respiratory and gastrointestinal (GI) outcomes in children with congenital diaphragmatic hernia (CDH). Self-reported respiratory and GI outcomes correlated with prenatal severity indicators. Prospective study at three fetal medicine units. Families of children prenatally diagnosed with isolated, left-sided CDH surviving for >1 year. Families received validated questionnaires for GI outcomes (Infant Gastroesophageal Reflux Questionnaire Revised, I-GERQ-R, for infants aged <2 years, or Paediatric Gastro-oesophageal Symptom and Quality of Life Questionnaire, PGSQ, for children aged aged 2-8 years or >9 years) and respiratory outcomes (preschool respiratory outcome questionnaire, for children aged ≤5 years, or the International Study of Asthma and Allergies in Childhood asthma questionnaire, for children aged 6-8 years or ≥9 years). Prenatal data collected from the medical records included lung size (percentage observed/expected lung-to-head ratio, O/E LHR %), liver position, fetal endoluminal tracheal occlusion (FETO) gestational age (GA) at delivery, and perinatal data included birthweight, location, patch repair and respiratory support. The GI and respiratory scores were correlated with O/E LHR using linear and logistic regression models. Univariate analysis was used to evaluate associations with perinatal variables. We obtained 142 responses from 342 families (representing a response rate of 45%). The baseline characteristics of participants and non-participants were comparable. No correlations between perinatal variables and respiratory or GI scores were identified. Children aged ≤5 years with lower O/E LHR values reported higher respiratory scores (P = 0.0175); this finding was not reported in older children. Overall, the children who underwent FETO (n = 51) had GI (P = 0.290) and respiratory (P = 0.052) scores that were comparable with those of children who were expectantly managed. Families and children with prenatally diagnosed CDH reported fewer respiratory symptoms with increasing age. There was no correlation between O/E LHR or the use of FETO and self-reported outcomes.

Posterior Skirt Technique with Mitral Valve Replacement for Mitral Annular Calcification

AbstractSevere mitral annular calcification (MAC) presents a surgical challenge due to the complexity of disease and the risk of valve replacement. There have been a variety of techniques to combat this risk including edge-to-edge repair, collar-enforced prosthesis, and pericardial patch techniques. This report highlights a case in which a novel reproducible surgical technique was used to prevent perivalvular leak with mitral valve replacement. This technique may add to surgeons' repertoire in addressing patients with MAC concentrated on the posterior annulus.

Machine Learning Quantification of Pulmonary Regurgitation Fraction from Echocardiography.

Assessment of pulmonary regurgitation (PR) guides treatment for patients with congenital heart disease. Quantitative assessment of PR fraction (PRF) by echocardiography is limited. Cardiac MRI (cMRI) is the reference-standard for PRF quantification. We created an algorithm to predict cMRI-quantified PRF from echocardiography using machine learning (ML). We retrospectively performed echocardiographic measurements paired to cMRI within 3months in patients with ≥ mild PR from 2009 to 2022. Model inputs were vena contracta ratio, PR index, PR pressure half-time, main and branch pulmonary artery diastolic flow reversal (BPAFR), and transannular patch repair. A gradient boosted trees ML algorithm was trained using k-fold cross-validation to predict cMRI PRF by phase contrast imaging as a continuous number and at > mild (PRF ≥ 20%) and severe (PRF ≥ 40%) thresholds. Regression performance was evaluated with mean absolute error (MAE), and at clinical thresholds with area-under-the-receiver-operating-characteristic curve (AUROC). Prediction accuracy was compared to historical clinician accuracy. We externally validated prior reported studies for comparison. We included 243 subjects (median age 21years, 58% repaired tetralogy of Fallot). The regression MAE = 7.0%. For prediction of > mild PR, AUROC = 0.96, but BPAFR alone outperformed the ML model (sensitivity 94%, specificity 97%). The ML model detection of severe PR had AUROC = 0.86, but in the subgroup with BPAFR, performance dropped (AUROC = 0.73). Accuracy between clinicians and the ML model was similar (70% vs. 69%). There was decrement in performance of prior reported algorithms on external validation in our dataset. A novel ML model for echocardiographic quantification of PRF outperforms prior studies and has comparable overall accuracy to clinicians. BPAFR is an excellent marker for > mild PRF, and has moderate capacity to detect severe PR, but more work is required to distinguish moderate from severe PR. Poor external validation of prior works highlights reproducibility challenges.

Effect of bondline thickness on the mechanical performance of CFRP laminate with asymmetric damage repaired by double-sided adhesive patch

As a common CFRP repair method, double-sided adhesive patch has been widely used in the automotive and aeronautic industry. More specific research is thus needed to help better understanding the effect of repairing parameters on the mechanical performance of CFRP structures after patch bonding. In this paper, experimental and Finite Element Modelling (FEM) efforts were made on the adhesive repaired CFRP laminate with different bondline thicknesses. Artificial damage was prefabricated in the centre of the CFRP laminate, which was then repaired through double-sided adhesive patch. Quasi-static tensile tests were conducted on the repaired specimen up to failure, to obtain the load-displacement curves. With a bondline thickness of 0.5 mm, the repaired CFRP structure reached its maximum peak load, increased by 25.3% and 26.4% compared to 0.2 mm and 1.0 mm bondline thicknesses, respectively. SEM observations were used to analyse the influence of adhesive thickness on the fracture modes. Combined with Cohesive Zone Model (CZM) for the adhesive layer and Hashin damage criterion for the CFRP, the FE model of the CFRP laminate repaired with double-sided adhesive patch subjected to tensile loading was established. Finally, the damage evolution as well as the failure modes in the parent laminate and adhesive layer with different bondline thicknesses were compared and analysed. It was revealed that bondline thickness can effectively affect the mechanical performance of CFRP laminate after adhesive patch repair.

May 2024 Medical Image of the Month: Hereditary Hemorrhagic Telangiectasia in a Patient on Veno-Arterial Extra-Corporeal Membrane Oxygenation

No abstract available. Manuscript truncated after 150 words. A 54-year-old man with a complex cardiac history, including Tetralogy of Fallot requiring Blalock-Taussig shunt in infancy, infundibular patch repair at age 7, and bioprosthetic tricuspid valve replacement at age 52, had ongoing frequent hospitalizations with decompensated right ventricular heart failure secondary to native pulmonary valve mixed stenosis plus regurgitation and left pulmonary artery stenosis. His case was further complicated by his history of hereditary hemorrhagic telangiectasia (HHT) with recurrent epistaxis and recent GI bleeds with multiple angiodysplastic lesions throughout the stomach, duodenum, and descending colon which were previously treated with argon plasma coagulation. The patient was admitted to our hospital in NYHA class IV heart failure receiving a continuous dopamine infusion and aggressive diuresis. Upon admission, a right heart catheterization demonstrated severe pulmonary valve regurgitation, left pulmonary artery stenosis, and systemic hypoxemia suggestive of an intrapulmonary shunt. Admission transthoracic echocardiogram demonstrated normal left ventricular ejection fraction of 55-60%, a …

Experimental and numerical studies on compressive failure behaviors of stepped-scarf repaired composite stiffened panels

Composite materials have been widely used in aerospace and other fields due to their superior mechanical properties. The repair of composite structures has received increasing attention in recent decades. In this work, the compressive failure behaviors of intact, defective and stepped-scarf repaired composite stiffened panels are analyzed experimentally and numerically. The evaluation of repair schemes of composite stiffened panels based on finite element (FE) analysis is investigated by comparison with experimental results. The maximum absolute value of error in load-carrying capacity between the numerical and experimental results does not exceed 3.65%. Progressive failure analysis model and cohesive zone model are utilized to reveal the damage evolution of multilayered composites and adhesive film. The failure modes obtained from FE analysis are in good agreement with the experimental observations. Moreover, the influence of the stepped-scarf ratio and repair patch angle deviation on the compressive strength is investigated to determine optimum repair parameters based on the established FE models. On the basis of the conducted studies, the results provide valuable insights into the evaluation and validation of repair schemes for composite stiffened panels with high accuracy and cost-effectiveness.

Improving the bonding performance of new and old cement pastes by high-temperature treatment on the surface of old cement pastes

In concrete structure repair projects, patch repair is one of the most commonly used methods. However, the bonding interface is often the weakest part of the overall repaired structure, and its performance affects the safety of the entire structure. In this study, different groups of cement specimens with similar exposed surface were prepared by splitting the cement paste samples with water–cement ratio of 0.4 and 0.2 into two halves from the middle point. The exposed/split surfaces were then activated in an oven at 600 °C, 700 °C and 800 °C (heating time 30 min and holding time 5 min) respectively, and the new cement pastes were poured on the treated surface of the old cement paste samples after the treated samples were cooled down to room temperature. The interface bonding strengths of different groups of samples were tested through a three-point bending test, and the interface microstructure and composition were analyzed through micro indentation, scanning electron microscopy, and X-ray diffraction tests. Among them, the interface bonding effect was the best with treatment temperature of 800 °C with an increase of more than 80 %. With this activation method, the old base cement can undergo rehydration reaction with the water in newly covered cement paste, thereby improving the bonding performance of the interface. However, high temperature can also cause microcracks on the surface of the old cement block, and it is necessary to control the activation temperature to achieve the required performance improvement. Combining mechanical tests, interface microstructure tests, and mechanism analysis, this study proposed and verified a method to improve the bonding interface strength between new and old cement pastes by high-temperature treatment on the surface of the old cement paste. Engineering applications were also discussed and explored.

Tricuspid valve repair for infective endocarditis.

The progressive increase in the use of implantable electronic devices, vascular access for dialysis and the increased life expectancy of patients with congenital heart diseases has led in recent years to a considerable number of right-side infective endocarditis, especially of the tricuspid valve (TV). Although current guidelines recommend TV repair for native tricuspid valve endocarditis (TVE), the percentage of valve replacements remains very high in numerous studies. The aim of our study is to analyse our experience in the treatment of TVE with a reparative approach. This case series includes all the patients who underwent surgery for acute or healed infective endocarditis on the native TV, at the Cliniques Universitaires Saint-Luc (Bruxelles, Belgium) between February 2001 and December 2020. Thirty-one patients were included in the study. Twenty-eight (90.3%) underwent TV repair and 3 (9.7%) had a TV replacement with a mitral homograft. The repair group was divided into 2 subgroups, according to whether a patch was used during surgery or not. Hospital mortality was 33.3% (n = 1) for the replacement group and 7.1% (n = 2) for repair (P = 0.25). Overall survival at 10 years was 75.6% [95% confidence interval (CI): 52-89%]. Further, freedom from reoperation on the TV at 10 years was 59.3% (95% CI: 7.6-89%) vs 93.7% (95% CI: 63-99%) (P = 0.4) for patch repair and no patch use respectively. Freedom from recurrent endocarditis at 10 years was 87% (95% CI: 51-97%). Considering that TVE is more common in young patients, a repair-oriented approach should be considered as the first choice. In the case of extremely damaged valves, the use of pericardial patch is a valid option. If repair is not feasible, the use of a mitral homograft is an additional useful solution to reduce the prosthetic material.

Surgical techniques using an attached patch for large left ventricular pseudoaneurysm after inferior acute myocardial infarction.

We report a case of large left ventricular pseudoaneurysm after inferior acute myocardial infarction. Patch repair is commonly performed; however, only a few studies have described specific surgical techniques for left ventricular pseudoaneurysm repair of the inferior left ventricular wall. As an optimal repair technique for left ventricular pseudoaneurysm of the inferior left ventricular wall is lacking, we believe our technique is safe and effective in repairing this pathology.

An experimental investigation of tensile residual strength of repaired composite laminates after low velocity impact

Low Velocity Impact (LVI) of Carbon Fibre Reinforced Polymer (CFRP) components are common during the manufacture and in-service life of aerostructures. However, the resulting effect on structural mechanical properties has not been extensively studied when the damage occurs on repaired components, which are already compromised to some degree. This research considers the relative mechanical performance of CFRP parts that are (1) pristine, (2) repaired using the stepped scarf method, and (3) repaired then impact damaged (low velocity impact at 5 J energy). For each case, subsurface damage was visually investigated and detailed measurements taken including impact load–time/energy–time behaviour, and post-impact tensile maximum force, stress and strain (and homogenised Young's modulus) before fracture. Further, three different repair patch sizes were considered. The experiments show that negligible surface impact damage was present in all repair cases but that delamination and debonding occurred for all but large repairs. For small and medium repair patches, 71% and 83% of the static strength of pristine samples were observed, with nearly full recovery for large repairs. After LVI, the strength of small repairs did not decrease whereas that of medium repairs declined to 77%. Interestingly, LVI did not have any impact on load bearing capability of large repairs. Stiffness measurements increased with repair size, even exceeding the value for pristine samples in some cases. The maximum stresses sustained were 67%, 77% and 85% that of a pristine sample for small, medium, and large repairs respectively.

Repair of a fistula between the aorta and right ventricular outflow tract secondary to infective endocarditis of a unicuspid aortic valve and previously repaired ventricular septal defect

BackgroundInfective endocarditis of the aortic valve can result in a wide range of destructive pathology beyond the valve leaflets and annulus which require careful surgical planning to provide appropriate debridement and reconstruction. Failure to do so can result in a failure of surgical treatment, recurrent infection and cardiac failure with concomitant high morbidity and mortality.Case reportWe describe the case of a 45-year-old male with previous patch repair of a ventricular septal defect, who was diagnosed with sub-acute bacterial endocarditis of the native aortic valve and developed a new fistula from the aorta to the right ventricular outflow tract which. This was managed surgically.ConclusionThis unique case highlights another spectrum of infective endocarditis with a unique approach to repair and management.

Optimize design of composite laminate scarf patch repair by numerical analysis and experiments

Optimize design of composite laminate scarf patch repair by numerical analysis and experiments

Optimization of Alkali Activator on the Strength Properties of Fly Ash Based Geopolymer Repair Materials

Flexible and rigid road pavement deteriorates over time and needs high-performance patching repair materials. Cold mix asphalt patching is an easy and inexpensive repair material to repair potholes and other damaged roads. However, the repaired road pavement fails because it doesn’t have adequate compressive and bonding strength to the substrate. Thus, this research uses high-performance geopolymer repair materials to patch against road pavement potholes substrate. Geopolymer repair materials could improve the bonding strength, making them suitable for road repair purposes. For making geopolymer repair materials, the main materials used were high calcium aluminosilicate source materials such as fly ash, sodium hydroxide, sodium silicate, and water. This study tested the compressive and bonding strength of geopolymer repair materials after 1, 7, 14, and 28 days. This study found that the compressive strength of 90 g of alkali activator was the highest, at 37.0 MPa. The bonding strength improved gradually from day 1 to day 14, and then considerably on day 28. The compressive strength and bonding strength both increase in direct proportion to the amount of alkali activator present. Alkali activator is optimal at 90 grams for compressive strength and bonding strength of geopolymer repair materials.

Comparative validation of corrosion simulation accuracy in patch-repaired reinforced concrete structures

ABSTRACT The evaluation of patch-repaired concrete’s performance, along with the development of a practical design guideline, necessitates considering multiple factors such as the quality of the existing concrete and the types of repair concrete used. The numerical model presented herein offers insights into the distribution of corrosion potential and corrosion rate in reinforcing steel, thereby assisting in monitoring the performance of the patch-repaired system. This model is constructed based on an analysis of the polarization behavior of steel across different concrete mixtures, with its validity confirmed through comparison with empirical results. Particularly, the model accounts for imperfect bonding between the patch and the substrate, a critical factor in repair effectiveness. The numerical outputs demonstrate consistent potential profiles, with minimal differences observed between empirical and simulated results. The incorporation of additional layers at the interface can significantly impact potential measurements, highlighting the discontinuity between the patch and substrate. Visual inspections further validate the numerical predictions by evidencing the corrosion rate distribution on steel surfaces under various patch repair scenarios.

Asymmetric porous composite hydrogel patch for microenvironment-adapted repair of contaminated abdominal wall defects

Effective antibacterial property and long-term mechanical support are essential for the repair of complex abdominal wall defects associated with infection. However, clinically available repair materials often fail to meet these requirements, resulting in high surgical failure rate and complications. In this study, an asymmetric porous composite hydrogel patch (cCS/PVA@BAC) with antibacterial, anti-adhesion, pro-healing, and durable mechanical support properties is designed for the efficient repair of contaminated abdominal wall defects. By stepwise phase-conversion and soaking method, robust and stable polyvinyl alcohol hydrogel (PVAH) is integrated with the biocompatible multicomponent hydrogel made of chitosan and carboxymethyl chitosan (cCS), and benzalkonium chloride (BAC) is loaded to enhance the antibacterial property. The cCS layer of cCS/PVA@BAC has an extracellular matrix-like porous structure, which can promote fibroblasts adhesion and wound healing. In contrast, the PVAH layer on the other side with a smooth and dense structure, which can reduce fibroblasts adhesion and prevent visceral adhesion. In addition, the composite hydrogel patch has good anti-swelling and anti-deformation properties as well as stable mechanical strength, thus can withstand high intraperitoneal pressure in the wet internal microenvironment. The loaded BAC can efficiently kill bacteria and improve the local inflammatory microenvironment. With these advantages, cCS/PVA@BAC can significantly reduce inflammation, promote tissue remodeling, and accelerate the healing of contaminated abdominal wall defects in the rat model. These findings suggest a potential use of multifunctional hydrogel patch as an ideal material for effective repair of contaminated soft tissue defects.