Patch Material Research Articles

A Review of Advanced Abdominal Wall Hernia Patch Materials.

Tension-free abdominal wall hernia patch materials (AWHPMs) play an important role in the repair of abdominal wall defects (AWDs), which have a recurrence rate of <1%. Nevertheless, there are still significant challenges in the development of tailored, biomimetic, and extracellular matrix (ECM)-like AWHPMs that satisfy the clinical demands of abdominal wall repair (AWR) while effectively handling post-operative complications associated with abdominal hernias, such as intra-abdominal visceral adhesion and abnormal healing. This extensive review presents a comprehensive guide to the high-end fabrication and the precise selection of these advanced AWHPMs. The review begins by briefly introducing the structures, sources, and properties of AWHPMs, and critically evaluates the advantages and disadvantages of different types of AWHPMs for AWR applications. The review subsequently summarizes and elaborates upon state-of-the-art AWHPM fabrication methods and their key characteristics (e.g., mechanical, physicochemical, and biological properties in vitro/vivo). This review uses compelling examples to demonstrate that advanced AWHPMs with multiple functionalities (e.g., anti-deformation, anti-inflammation, anti-adhesion, pro-healing properties, etc.) can meet the fundamental clinical demands required to successfully repair AWDs. In particular, there have been several developments in the enhancement of biomimetic AWHPMs with multiple properties, and additional breakthroughs are expected in the near future.

Itaconate and citrate releasing polymer attenuates foreign body response in biofabricated cardiac patches

Application of cardiac patches to the heart surface can be undertaken to provide support and facilitate regeneration of the damaged cardiac tissue following ischemic injury. Biomaterial composition is an important consideration in the design of cardiac patch materials as it governs host response to ultimately prevent the undesirable fibrotic response. Here, we investigate a novel patch material, poly (itaconate-co-citrate-co-octanediol) (PICO), in the context of cardiac implantation. Citric acid (CA) and itaconic acid (ITA), the molecular components of PICO, provided a level of protection for cardiac cells during ischemic reperfusion injury in vitro. Biofabricated PICO patches were shown to degrade in accelerated and hydrolytic conditions, with CA and ITA being released upon degradation. Furthermore, the host response to PICO patches after implantation on rat epicardium in vivo was explored and compared to two biocompatible cardiac patch materials, poly (octamethylene (anhydride) citrate) (POMaC) and poly (ethylene glycol) diacrylate (PEGDA). PICO patches resulted in less macrophage infiltration and lower foreign body giant cell reaction compared to the other materials, with corresponding reduction in smooth muscle actin-positive vessel infiltration into the implant region. Overall, this work demonstrates that PICO patches release CA and ITA upon degradation, both of which demonstrate cardioprotective effects on cardiac cells after ischemic injury, and that PICO patches generate a reduced inflammatory response upon implantation to the heart compared to other materials, signifying promise for use in cardiac patch applications.

Mid-term results following pulmonary artery patch augmentation in congenital heart disease.

Treatment of pulmonary artery (PA) stenosis in congenital heart disease is associated with adverse outcomes. The aim of this retrospective cohort study was to compare outcomes after surgical patch augmentation of PA stenosis in patients with biventricular congenital heart disease using different patch materials. We identified all patients from our institutional congenital heart disease database who underwent patch augmentation for PA stenosis on the main pulmonary artery (MPA) or PA branches between 2012 and 2018. Patch materials used were glutaraldehyde fixated autologous pericardium (AP), expanded polytetrafluoroethylene (ePTFE), equine pericardium (EP), and bovine pericardium (BP). The primary study endpoint was the composite of catheter-based re-intervention or re-operation to relieve recurrent stenosis at the site of prior implanted patch material. A total of 156 patients (median age, 5 months, range, 0-85 months; median weight, 6.2 kg, range, 2.8-15.0 kg) underwent patch augmentation using 163 patches (ePTFE =99, 61%; EP =34, 21%; AP =25, 15%; BP =5, 3%). Overall, 131 (84%) patients underwent patch augmentation at the MPA, and 25 (16%) patients underwent patch augmentation at one or both PA branches. Over a mean follow-up period of 4±2 years, 30 patients (19%) reached the study endpoint. Freedom from primary endpoint was 92%±3% for the MPA and 25%±9% for PA branches at 5 years, respectively (P<0.001). Comparison of patch materials revealed similar re-intervention rates between ePTFE, AP, and EP. In contrast, outcomes were significantly decreased following the usage of BP when compared to other materials (ePTFE vs. BP, P=0.01; EP vs. BP, P=0.005). In the multivariable analysis, lower weight at index operation, patch augmentation of PA branches, and usage of BP were independently associated with re-intervention. Patch augmentation of the MPA was associated with acceptable outcomes, while patch augmentation of PA branch stenosis remained independently associated with re-intervention. None of the used patch materials demonstrated superiority; however, BP had a higher rate of re-interventions.

An in vitro characterization of a PCL-fibrin scaffold for myocardial repair

Each year in the United States approximately 10,000 babies are born with a complex congenital heart defect (CHD) requiring surgery in the first year of after birth. Several of these operations require the implantation of a full-thickness heart patch; however, the current patch materials available to pediatric heart surgeons are exclusively non-living and non-degradable, which do not grow with the patient and are prone to fail due to an inability to integrate with the heart. In this work, the goal was to develop a full-thickness, tissue engineered myocardial patch (TEMP) that is made from biodegradable components, strong enough to withstand the mechanical forces of the heart wall, and able to integrate with the heart and drive neotissue formation. Here, a thick and porous electrospun PCL scaffold filled with high-salt PEGylated fibrin was developed. The scaffold was found to be mechanically sufficient for heart wall repair. Vascular cells were able to infiltrate more than halfway through the scaffold in static culture within three weeks. The scaffold maintained pluripotent stem cells for at least four days, supports viable iPSC-derived cardiomyocytes, and fostered tissue thickening in vitro. The TEMP developed here and tested in vitro is promising for the repair of structural CHD and will next be assessed in situ.

Use of glutaraldehyde-treated autologous pericardial patch in complete atrioventricular septal defect repair.

Synthetic patch materials, such as polytetrafluoroethylene and knitted polyester, are commonly used for the repair of complete atrioventricular septal defects using the double-patch technique. In our study, we investigated the impact of glutaraldehyde-treated autologous pericardial patch on postoperative atrioventricular valve function. In this retrospective study, patients who underwent repair of complete atrioventricular septal defects using the double-patch technique between January 1, 2018, and May 15, 2023, at our pediatric cardiac center were included in the study. Patients were divided into two groups based on the type of patch used for the repair of the ventricular component of the atrioventricular septal defect: autologous pericardial patch (group 1) and polytetrafluoroethylene patch (group 2). Postoperative data of the patients were retrospectively analyzed. Thirty-four patients (57.6%) were female, and 25 (42.4%) were male, with a median age of 7 (5-18) months. The median body weight at the time of surgery was 5.5 (4.1-10) kilograms. Down syndrome was present in 45 (76.3%) patients. The autologous pericardium was used for ventricular septal defect closure in 44 (74.6%) patients (Group 1), while polytetrafluoroethylene was used in 15 (25.4%) patients (Group 2). Permanent cardiac pacemaker placement was required in 4 (6.8%) patients due to postoperative atrioventricular block. Hospital mortality was 11.9% (n=7). Among these cases, 4 (6.8%) patients died from low cardiac output syndrome, and 3 (5.1%) patients died from sepsis. Postoperative echocardiographic evaluation revealed insignificant residual ventricular septal defects in 17 (28.8%) patients. No significant differences were observed between the groups in terms of mortality and postoperative atrioventricular valve insufficiency. The median follow-up duration for discharged patients was 5 months (7 days to 3.9 years). Throughout the follow-up period, there were no reoperations due to valve insufficiency or left ventricular outflow tract obstruction. Glutaraldehyde-treated autologous pericardium is a safe material that can be confidently used for the repair of the ventricular component of complete atrioventricular septal defects. This patch material does not adversely affect atrioventricular valve function and allows for the successful closure of ventricular septal defects.

Mechanical failure analysis of patch materials used in aortic arch reconstruction: implications for clinical practice.

Thick-patch pulmonary homograft, autologous pericardium and CardioCel Neo are common patch materials for aortic arch reconstruction. Insufficient data exist on sutured patch strength and limits of use. We evaluated failure strength of these materials to develop a failure prediction model for clinical guidance. Patch failure strength was evaluated via sutured uniaxial and burst pressure testing. In sutured uniaxial testing, patches were sutured to aortic or Dacron tabs and pulled to failure. In burst pressure testing, patches were sewn into porcine aortas or Dacron grafts and pressurized to failure. Failure membrane tension was calculated. A prediction model of membrane tension versus vessel diameter was generated to guide clinical patch selection. Combining sutured uniaxial and burst pressure test data, pulmonary homograft failure strength {0.61 [interquartile range (IQR): 0.44, 0.78] N/mm, n = 21} was less than half that of autologous pericardium [2.22 (IQR: 1.65, 2.78) N/mm, n = 15] and CardioCel Neo [1.31 (IQR: 1.20, 1.42) N/mm, n = 20]. Pulmonary homograft burst pressure [245 (IQR: 202, 343) mmHg, n = 7] was significantly lower than autologous pericardium [863 (IQR: 802, 919) mmHg, n = 6] and CardioCel Neo [766 (IQR: 721, 833) mmHg, n = 6]. Our model predicts failure limits for each patch material and outlines safety margins for combinations of aortic diameter and pressure. Sutured failure strength of thick-patch pulmonary homograft was significantly lower than autologous pericardium and CardioCel Neo. Patient selection (predicted postoperative arch diameter and haemodynamics) and blood pressure management must be considered when choosing patch material for arch reconstruction. In older children and adolescents, autologous or bovine pericardium may be more suitable materials for aortic patch augmentation to minimize the risk of postoperative patch failure.

Spin Coated Multi‐Walled Carbon Nanotube Patch Antenna for Breast Cancer Detection

AbstractEarly detection of breast cancer can be a life‐saving measure for many patients. The inaccessibility of X‐rays, magnetic resonance imaging (MRI), and other medical facilities in many resource‐constrained areas hinders the early detection of breast cancer. In this paper, the use of a rectangular patch antenna for breast cancer detection is proposed by using multiwall carbon nanotubes (MWCNTs) as patch material. The proposed antenna is designed by CST software which is (30 × 40 × 1.66) mm in dimension. A breast model is designed including tumor and cancerous tumors by specific tissue properties for observing the antenna performance in different cases. In free space, the return loss of the designed antenna is observed at −33.414 dB. Moreover, the S11 is examined in a normal breast, a breast including a normal tumor, and a breast including a cancerous tumor is −32.641 dB, −34.94 dB, and −35.22 dB respectively. It can be utilized on a human body phantom model due to its adaptability and reduced radiation properties. The proposed antenna is miniature in size, cost‐effective, easily portable, and eco‐friendly. It can be used as a first screening tool for breast cancer patients, particularly in resource‐constrained regions.

Effect of four eggshell repair materials on weight loss during incubation of white leghorn chicken eggs.

Egg weight loss during incubation is a key indicator used to monitor successful egg development and is closely related to hatchability and chick survival. Artificial incubation is one of the most important captive breeding techniques used in conservation efforts to bolster avian populations. To repair damage to the eggshell and ensure embryonic viability during incubation, a variety of repair coverings can be applied. This study tested the impact of four repair materials (nail polish, synthetic glue, medical dressing, and molten wax film) on egg weight loss during incubation. We found no impact on weight loss for coverings smaller than 35% of the eggshell surface, nor did we find any differences between covering types. The average egg weight loss decreased as the coverage area increased, and the weight loss did not differ when blunt versus sharp-end coverings were compared. Given the relative insensitivity of egg weight loss and survival to the type of patch material used, we concluded that the selection of material for the purpose of weight loss management could be based on practical considerations, such as ease of application and availability.

Development of Procaine Loaded Transdermal Patches Based on Biopolymer Pectin, Castor Oil, and Polyethylene Glycol for Controllable Drug Release Studies and Their Characterizations

AbstractTransdermal drug delivery systems have considerable attention in clinical and point‐of‐care applications due to their superior advantages such as non‐invasive properties and keeping drug efficiency. To overcome the skin barrier, penetration enhancers are employed in the patch design. Chemical penetration enhancers are the most frequently applied way to improve drug diffusion through the barrier. Transdermal patches are designed as a drug‐loaded thin‐film hydrogel. Since the patch material must be biocompatible and eco‐friendly, in this study, pectin‐based transdermal patches are designed, and procaine, a painkiller drug is chosen as a model drug. Benzyl alcohol, polyethylene glycol, and castor oil are selected as chemical penetration enhancers. Drug diffusion experiments are carried out by using Franz diffusion cells at 37 °C. Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) are used to characterize the chemical structure and thermal properties of the patches. The patches are evaluated by the contact angle measurement and the swelling test in terms of their hydrophilicity and water uptake. Regarding in vitro drug release experiments by Franz diffusion cells, drug‐loaded patches were examined (CxPy‐PC; C‐castor oil, P‐PEG, x‐y amounts (mg)). It is found that the most promising results come from C10‐P5‐PC (12.7 mg drug/g film) and C30‐P5‐PC (11.4 mg drug/ g film) which can be attributed to the synergetic and optimum amount of polyethylene glycol and castor oil.

An Ex Vivo Porcine Model for Hydrodynamic Testing of Experimental Aortic Valve Procedures and Novel Medical Devices.

The options for testing new cardiac procedures and investigative medical devices prior to use in an animal model are limited. In this study, we present a method for mounting a porcine aortic valve in a pulse duplicator to evaluate its hydrodynamic properties. These properties can then be evaluated before and after the procedure under investigation is performed and/or the investigative medical device is applied. Securing the inflow segment presents some difficulty owing to the lack of circumferential myocardium in the left ventricular outflow tract. This method addresses that issue by securing the inflow segment using the anterior leaflet of the mitral valve and then suturing the left ventricular free wall around the inflow fixture. The outflow segment is secured simply by inserting the fixture into an incision in the superior aspect of the aortic arch. We found that specimens had significantly different hydrodynamic properties before and after tissue fixation. This finding induced us to use fresh specimens in our testing and should be considered when using this method. In our work, we used this method to test novel intracardiac patch materials for use in the valvular position by performing an aortic valve neocuspidization procedure (Ozaki procedure) on the mounted porcine aortic valves. These valves were tested before and after the procedure to assess the change in hydrodynamic properties in comparison to the native valve. Herein, we report a platform for hydrodynamic testing of experimental aortic valve procedures that enables comparison with the native valve and between different devices and techniques used for the procedure under investigation.

Determination of the effects of nanoparticle reinforcements on mechanical and composite surface fractures in joints bonded with epoxy adhesives

Various studies are carried out to increase the strength of the joints made with adhesives. One of these studies is to investigate the use of nanoparticles as reinforcement elements in adhesives. In this study, the tensile strength of the bonding joints made by adhesives DP410, DP460 and DP490 epoxy adhesives at the rates of 0.1, 0.2, 0.3 and 0.4% wt. of the graphene nanoparticles (GNP) were investigated. AA5754 aluminum alloys and glass fiber reinforced composites were used as adherent and patches, respectively. Tensile tests were carried out to determine the effect of reinforcement ratios on adhesive bonds. After the tensile tests, macro and scanning electron microscopy (SEM) images were taken to examine the adhesion damage between nanoparticle, adhesive and adherent surfaces. In the results of the tensile test experiments, the tensile strength of all the joints in which the reinforcement element is used was higher than the non-reinforced bonding. The highest tensile strength in GNP-reinforced joints using DP410 and DP490 adhesives was obtained as 5674.4 and 4837.4 MPa, respectively, at 0.2% wt. reinforcement rate. However, the highest tensile strength of all experiments was obtained as 6154.4 MPa in DP460 adhesive, where 0.3% wt. reinforcement ratio was used. In the damage analyses made after the tensile tests, it was observed that there were fiber breaks in the glass fiber composite used as the patch material in the bonding joints, where homogeneity was formed between the surfaces of the GNP and the epoxy adhesive. Especially, this situation occurred in the joints where 0.2% wt. in DP410 adhesive and 0.2% wt. and 0.3% wt. of reinforcement ratios of DP460 adhesive joints were used. Finally, in the fatigue tests, the GNP particle reinforcement increased the fatigue life of the adhesive joints.

Validation of a laser projection platform for the preparation of surgical patches used in paediatric cardiac surgery.

Reconstruction of cardiovascular anatomy with patch material is integral to the repair of congenital heart disease. We present validation of a laser projection platform for the preparation of surgical patches as a proof-of-concept for intraoperative use in patient-specific planning of paediatric cardiac surgery reconstructions. The MicroLASERGUIDE, a compact laser projection system that displays computer-aided designs onto 2D/3D surfaces, serves as an alternative to physical templates. A non-inferiority comparison of dimensional measurements was conducted between laser projection ('laser') and OZAKI AVNeo Template ('template') methods in creation of 51 (each group) size 13 valve leaflets from unfixed bovine pericardium. A digital version of the OZAKI AVNeo Template dimensions served as control. Feasibility testing was performed with other common patch materials (fixed bovine pericardium, PTFE and porcine main pulmonary artery as a substitute for pulmonary homograft) and sizes (13, 23) (n = 3 each group). Compared to control (height 21.5, length 21.0 mm), template height and length were smaller (height and length differences of -0.3 [-0.5 to 0.0] and -0.4 [-0.8 to -0.1] mm, P < 0.01 each); whereas, both laser height and length were relatively similar (height and length differences of height 0.0 [-0.2 to 0.2], P = 0.804, and 0.2 [-0.1 to 0.4] mm, P = 0.029). Template percent error for height and length was -1.5 (-2.3 to 0.0)% and -1.9 (-3.7 to -0.6)% vs 0.2 (-1.0 to 1.1)% and 1.0 (-0.5 to 1.8)% for the laser. Similar results were found with other materials and sizes. Overall, laser sample dimensions differed by a maximum of 5% (∼1 mm) from the control. The laser projection platform has demonstrated promise as an alternative methodology for the preparation of surgical patches for use in cardiac surgery. This technology has potential to revolutionize preoperative surgical planning for numerous congenital anomalies that require patient-specific patch-augmented repair.

Shallow suture at ventricular septal defect may safely reduce right bundle branch block.

To avoid rhythm disturbance, sutures for ventricular septal defect closure have been traditionally placed 2∼5 mm or more away from the edge of the ventricular septal defect. However, the traditional suturing method appears to induce right bundle branch block and tricuspid valve regurgitation after ventricular septal defect closure more than our alternative technique, shallow suturing just at the edge of the ventricular septal defect (shallower bites at the postero-inferior margin). We aimed to verify our clinical experience of perimembranous ventricular septal defect repair. The alternative shallow suturing method has been applied since 2003 at our institution. We retrospectively reviewed the clinical data of 556 isolated perimembranous ventricular septal defect patients who underwent surgical closure from 2000 to 2019. We investigated the postoperative occurrence of right bundle branch block or progression of tricuspid regurgitation and analysed risk factors for right bundle branch block and tricuspid regurgitation. Traditional suturing method (Group T) was used in 374 cases (66.8%), and alternative suturing method (Group A) was used in 186 cases (33.2%). The right bundle branch block occurred more frequently in Group T (39.6%) than in Group A (14.9%). In multivariable logistic regression analysis, Group T and patch material were significant risk factors for late right bundle branch block. More patients with progression of tricuspid regurgitation were found in Group T. Shallow suturing just at the edge of the ventricular septal defect may reduce the rate of right bundle branch block occurrence and tricuspid regurgitation progression without other complications.

Human Adipose-Derived Mesenchymal Stem Cell-Secreted Extracellular Matrix Coating on a Woven Nanotextile Vascular Patch for Improved Endothelial Cell Response.

Biomedical implants possessing the structural and functional characteristics of extracellular matrix (ECM) are pivotal for vascular applications. This study investigated the potential of recreating a natural ECM-like structural and functional environment on the surface of biodegradable polymeric nanotextiles for vascular implants. Human adipose-derived mesenchymal stem cells (MSCs) were grown on a suitably engineered polycaprolactone (PCL) nanofibrous textile and were allowed to modify its surface through the deposition of MSC-specific ECM. This surface-modified nanotextile showed mechanical characteristics and functionality appropriate for vascular patch material. The uniformity of ECM coating significantly improved the viability, proliferation, and migration of human endothelial cells compared to bare and xenogeneic collagen-coated PCL nanotextile patches. Thus, a polymeric nanotextile, which is surface modified using MSC-driven ECM, provided a rapid and improved endothelialization, thereby suggesting its potential for vascular patch applications.

The aortic uncrossing procedure

ObjectiveCross-sectional imaging allows identification of rare patients with a vascular ring and circumflex aorta. The key diagnostic feature is crossing of the transverse aortic arch from right to left posterior to the trachea and superior to the carina in a patient with a right aortic arch. We evaluated our patients who received an aortic uncrossing procedure. MethodsWe reviewed all patients who underwent aortic uncrossing from 2002 to 2022. All patients received preoperative computed tomography imaging and bronchoscopy. ResultsEleven patients ranging in age from 1.5 to 10 years (median 4 years) underwent aortic uncrossing. Two patients had prior left ligamentum division, and 3 patients had prior left aortic arch division. All had significant clinical symptoms. Eight patients had deep hypothermic circulatory arrest (mean 34 minutes), and 3 patients had antegrade cerebral perfusion (median, 28 minutes). Patch material was not used for aortic augmentation, and no patient underwent a posterior tracheopexy or rotational esophagoplasty. Postoperative length of stay ranged from 4 to 31 days (median, 5 days). One patient required a temporary tracheostomy for bilateral recurrent laryngeal nerve paresis, which recovered. One patient required an aortic extension graft to alleviate esophageal compression from an unusual ectatic esophageal course. All patients had relief of airway symptoms and dysphagia. ConclusionsIn properly selected patients with a right aortic arch and circumflex aorta, aortic uncrossing is a safe and effective therapy to treat airway and esophageal compression. The procedure can be conducted with deep hypothermic circulatory arrest or antegrade cerebral perfusion. Careful attention to the location of the esophagus and recurrent laryngeal nerves is required.

How heterogeneous wettability enhances boiling

For super-heated water on a substrate with hydrophobic patches immersed in a hydrophilic matrix, one can choose the temperature so that micro-bubbles will form, grow and merge on the hydrophobic patches and not on the hydrophilic matrix. Until covering a patch, making a pinned macro-bubble, a bubble has a contact angle π−θ2, where θ2 is the receding contact angle of water on the patch material. This pinned macro-bubble serves as the initial condition of a quasi-static growth process, leading to detachment through the formation of a neck, so long as depinning and dewetting of the hydrophilic matrix was avoided during the growth of the pinned bubble: the bubble contact angle should not exceed π−θ1, where θ1 is the receding contact angle of water on the matrix material. The boiling process may then enter a cycle of macro-bubbles forming and detaching on the patches; the radii of these patches can be optimized for maximizing the heat transfer for a given substrate area. For this analysis to become quantitative, we revisit the Young–Laplace quasi-static evolution of key physical quantities, such as bubble energy, as functions of bubble growing volume, when gravity is either significative or negligible: this concerns both pinned bubbles on a fixed circular footprint (Dirichlet boundary conditions) and free un-pinned bubbles with a fixed contact angle (Neumann boundary conditions).

Fabrication of Patchy Silica Microspheres with Tailor-Made Patch Functionality using Photo-Iniferter Reversible-Addition-Fragmentation Chain-Transfer (PI-RAFT) Polymerization.

Their inherent directional information renders patchy particles interesting building blocks for advanced applications in materials science. In this study, a feasible method to fabricate patchy silicon dioxide microspheres is demonstrated, which they are able to equip with tailor-made polymeric materials as patches. Their fabrication method relies on a solid-state supported microcontact printing (µCP) routine optimized for the transfer of functional groups to capillary-active substrates, which is used to introduce amino functionalities as patches to a monolayer of particles. Acting as anchor groups for polymerization, photo-iniferter reversible addition-fragmentation chain-transfer (RAFT) is used to graft polymer from the patch areas. Accordingly, particles with poly(N-acryloyl morpholine), poly(N-isopropyl acrylamide), and poly(n-butyl acrylate) are prepared as representative acrylic acid-derived functional patch materials. To facilitate their handling in water, a passivation strategy of the particles for aqueous systems is introduced. The protocol introduced here, therefore, promises a vast degree of freedom in engineering the surface properties of highly functional patchy particles. This feature is unmatched by other techniques to fabricate anisotropic colloids. The method, thus, can be considered a platform technology, culminating in the fabrication of particles that possess locally precisely formed patches on particles at a low µm scale with a high material functionality.

Efficacy of patch technique for dural tear repair using hydrogel sealant: a pilot study

BACKGROUND CONTEXTDural tear is one of the common complications of lumbar spine surgery. Suture repair is often difficult due to the requirement of meticulous suture technique in limited space. Dural tear repair is particularly challenging in minimally invasive spine surgery. The patch technique, applying patch material and glue without suture, is an alternative method for dural tear repair. PURPOSETo verify the efficacy of patch technique for dural tear repair using polyethylene glycol hydrogel sealant and to compare patch materials. STUDY DESIGN/SETTINGBasic research. METHODSThere were three study groups: Group 1 (control group, n=4) had hydrogel sealant alone, Group 2 (n=8) had collagen sheet patch and hydrogel sealant, Group 3 (n=8) had mesh sheet patch and hydrogel sealant. A 4-mm durotomy was made in a piece of bovine dura using an arterial punch. Patch material (collagen or mesh sheet) was placed over the dural tear with 2 mm margin and then sprayed with hydrogel sealant. The pressure in the system was increased by 10 mm Hg and monitored. When the leakage occurred, the pressure threshold was measured. RESULTSThe mean pressure threshold for leakage was 32.5 (Standard deviation=15.0), 66.3 (37.0), and 88.8 (27.5) mm Hg for Group 1, 2 and 3, respectively. The mean pressure threshold for leakage for Group 3 was significantly higher than that for Group 1 (p<.05). There was no significant difference in the mean pressure threshold for leakage between Groups 1 and 2, and Groups 2 and 3. CONCLUSIONSPatch technique using mesh sheet and hydrogel sealant demonstrated significantly higher mean pressure threshold for leakage compared with hydrogel sealant alone. CLINICAL SIGNIFICANCEPatch technique using mesh sheet and hydrogel sealant without suture is potentially a reasonable option for dural tear repair in lumbar spine surgery.

Biogenic polymer-based patches for congenital cardiac surgery: a feasibility study.

Currently used patch materials in congenital cardiac surgery do not grow, renew, or remodel. Patch calcification occurs more rapidly in pediatric patients eventually leading to reoperations. Bacterial cellulose (BC) as a biogenic polymer offers high tensile strength, biocompatibility, and hemocompatibility. Thus, we further investigated the biomechanical properties of BC for use as patch material. The BC-producing bacteria Acetobacter xylinum were cultured in different environments to investigate optimal culturing conditions. For mechanical characterization, an established method of inflation for biaxial testing was used. The applied static pressure and deflection height of the BC patch were measured. Furthermore, a displacement and strain distribution analysis was performed and compared to a standard xenograft pericardial patch. The examination of the culturing conditions revealed that the BC became homogenous and stable when cultivated at 29°C, 60% oxygen concentration, and culturing medium exchange every third day for a total culturing period of 12 days. The estimated elastic modulus of the BC patches ranged from 200 to 530 MPa compared to 230 MPa for the pericardial patch. The strain distributions, calculated from preloaded (2 mmHg) to 80 mmHg inflation, show BC patch strains ranging between 0.6% and 4%, which was comparable to the pericardial patch. However, the pressure at rupture and peak deflection height varied greatly, ranging from 67 to around 200 mmHg and 0.96 to 5.28 mm, respectively. The same patch thickness does not automatically result in the same material properties indicating that the manufacturing conditions have a significant impact on durability. BC patches can achieve comparable results to pericardial patches in terms of strain behavior as well as in the maximum applied pressure that can be withstood without rupture. Bacterial cellulose patches could be a promising material worth further research.

Evaluation and comparison of patch materials used for pulmonary arterioplasty in pediatric congenital heart surgery

ObjectiveTo evaluate the long-term performance of the patch materials we have used to augment the pulmonary arterial tree across a wide spectrum of diagnoses and anatomical locations. MethodsRetrospective, single-center review of 217 consecutive pediatric patients at a tertiary referral center from 1993 to 2020 who underwent patch arterioplasty of the pulmonary arterial tree from the pulmonary bifurcation to the distal pulmonary arterial branches. Reintervention data were collected and analyzed. Lesion-specific anatomy and other variables were analyzed as risk factors for reintervention. ResultsThere were 280 total operations performed (217 initial operations and 63 reoperations) and 313 patches used. The patches used were autologous pericardium (166, 53.0%), pulmonary homograft (126, 40.3%), and a heterogeneous group of other materials (21, 6.7%). Overall patient survival was 86.2%, freedom from reoperation was 81.0% and freedom from reintervention (FFR) was 70.6%, with a median follow-up of 13.8 years (interquartile range, 6.3-17.9 years). For all patches, 10-, 20-, and 27-year FFR was 76.6%, 70.6%, and 70.6%, respectively. FFR was similar among all 3 patch type groups (P = .29). Multivariable Cox regression analysis showed that diagnoses of pulmonary atresia with ventricular septal defect and major aortopulmonary collateral arteries and hypoplastic left heart syndrome, patches placed at initial cardiac operation, and increasing number of cardiac operations were risk factors for reintervention. ConclusionsAutologous pericardium and pulmonary homograft patches performed similarly. Although patch type conferred no difference in need for reintervention, other risk factors did exist. Namely, diagnoses of pulmonary atresia with ventricular septal defect and major aortopulmonary collateral arteries and hypoplastic left heart syndrome, patch placement at a patient's first cardiac operation, and increasing number of cardiac operations were risk factors for reintervention.