Multiple Tissue Layers Research Articles

Highly protective and functional strengthening strategies for 3D printed continuous carbon fiber reinforced polymer composites: Manufacturing and properties

Carbon fiber-reinforced polymer (CFRP) composites have gradually emerged as a crucial material in the aerospace industry. However, inadequate impact resistance and thermal stability limit survival in extreme environments. Inspired by the specific functions of multiple layers of tissue, from bird feathers to the musculoskeletal system. We propose low-cost composite strengthening strategies and efficient novel three-dimensional graphene aerogel manufacturing methods. A novel graphene aerogel/carbon fiber reinforced polymer (GAC) composite prepared by in-situ laser-induced graphene (LIG) layers on the surface of 3D-printed CFRP. GAC composites enhance CFRP's impact protection, thermal insulation, and electromagnetic shielding capabilities. For protection, GAC composites reduce low-velocity impact damage by 26.2 %. The graphene layer can increase the thermal buffering capacity of the material four times, and the long-term service temperature can be increased by 40 % compared to traditional CFRP. For functionality, the composites enable electromagnetic interference (EMI) shielding effectiveness of up to 50.2 dB. Furthermore, it can achieve surface heating above 400 °C and rapid de-icing through electrothermal effects. The simple and efficient processing method of GAC composites and tunable functionalities holds promise for the development of highly protective and intelligent aircraft skins.

Enhancing EEG data quality and precision for cloud-based clinical applications: an evaluation of the SLOG framework

Automation is revamping our preprocessing pipelines, and accelerating the delivery of personalized digital medicine. It improves efficiency, reduces costs, and allows clinicians to treat patients without significant delays. However, the influx of multimodal data highlights the need to protect sensitive information, such as clinical data, and safeguard data fidelity. One of the neuroimaging modalities that produces large amounts of time-series data is Electroencephalography (EEG). It captures the neural dynamics in a task or resting brain state with high temporal resolution. EEG electrodes placed on the scalp acquire electrical activity from the brain. These electrical potentials attenuate as they cross multiple layers of brain tissue and fluid yielding relatively weaker signals than noise-low signal-to-noise ratio. EEG signals are further distorted by internal physiological artifacts, such as eye movements (EOG) or heartbeat (ECG), and external noise, such as line noise (50 Hz). EOG artifacts, due to their proximity to the frontal brain regions, are particularly challenging to eliminate. Therefore, a widely used EOG rejection method, independent component analysis (ICA), demands manual inspection of the marked EOG components before they are rejected from the EEG data. We underscore the inaccuracy of automatized ICA rejection and provide an auxiliary algorithm-Second Layer Inspection for EOG (SLOG) in the clinical environment. SLOG based on spatial and temporal patterns of eye movements, re-examines the already marked EOG artifacts and confirms no EEG-related activity is mistakenly eliminated in this artifact rejection step. SLOG achieved a 99% precision rate on the simulated dataset while 85% precision on the real EEG dataset. One of the primary considerations for cloud-based applications is operational costs, including computing power. Algorithms like SLOG allow us to maintain data fidelity and precision without overloading the cloud platforms and maxing out our budgets.

A Prospective Randomized Controlled Study of Stratafix versus Standard-of-Care for Deep Tissue Closure in Orthopedic Surgery.

Orthopedic deep surgical incisions require the approximation of 1 or multiple tissue layers. This prospective randomized controlled study aimed to assess the usefulness and effectiveness of a barbed suture technique (Stratafix symmetric PDS plus) versus the conventional interrupted knotted suture technique for deep tissue closure in orthopedic surgery by comparing deep fascia suture time, relative cost, and wound-related complications. A total of 254 patients with deep surgical incisions who underwent orthopedic surgery between October 1, 2020, and June 30, 2021, were recruited. Their general characteristics (age, sex, weight, height, body mass index, American Society of Anesthesiologists physical status score, total operation time, and length of deep incision) and factors related to deep incision wounds (suture type and number, wound closure time, and operation site outcomes) were collected. The general characteristics did not differ between the Stratafix and conventional groups. There were no between-group differences observed in total operation time or total anesthesia time. The wound suture times differed significantly. In the conventional group, the suture time per unit length was lower in the group with the length of deep incision under 20 cm but did not differ significantly for each wound size. In the Stratafix group, the suture time per unit length was lower in the group under 15 cm, with the shortest time observed for 10-14.9 cm, followed by 5.0-9.9 cm and the group under 5 cm. The conventional group developed 4 cases of superficial wound infection or surgical wound necrosis. One case of protruded suture tap occurred in the Stratafix group. The average suture time per unit length increased for lengths under 5 cm as barbed sutures required more time from the start of the first suture to finish of the last suture. There was no significant benefit for very short suture length. One barbed suture material allows a suture of approximately 10-12 cm; sutures beyond that require more time because the surgeon has to start again. The Stratafix group used less suture material than the conventional group.

Optical Transmission in Single-Layer Brain Tissues under Different Optical Source Types: Modelling and Simulation.

The human brain is a complex organ controlling daily activity. Present technique models have mostly focused on multi-layer brain tissues, which lack understanding of the propagation characteristics of various single brain tissues. To better understand the influence of different optical source types on individual brain tissues, we constructed single-layer brain models and simulated optical propagation using the Monte Carlo method. Based on the optical simulation results, sixteen optical source types had different optical energy distributions, and the distribution in cerebrospinal fluid had obvious characteristics. Five brain tissues (scalp, skull, cerebrospinal fluid, gray matter, and blood vessel) had the same set of the first three optical source types with maximum depth, while white matter had a different set of the first three optical source types with maximum depth. Each brain tissue had different optical source types with the maximum and minimum full width at half maximum. The study on single-layer brain tissues under different optical source types lays the foundation for constructing complex brain models with multiple tissue layers. It provides a theoretical reference for optimizing the selection of optical source devices for brain imaging.

Stomach tissue classification using autofluorescence spectroscopy and machine learning.

Determination of stomach tumor location and invasion depth requires delineation of gastric histological structure, which has hitherto been widely accomplished by histochemical staining. In recent years, alternative histochemical evaluation methods have been pursued to accelerate intraoperative diagnosis, often by bypassing the time-consuming step of dyeing. Owing to strong endogenous signals from coenzymes, metabolites, and proteins, autofluorescence spectroscopy is a favorable candidate technique to achieve this aim. We investigated stomach tissue slices and block specimens using a fast fluorescence imaging scanner. To obtain histological information from broad and structureless fluorescence spectra, we analyzed tens of thousands of spectra with multiple machine-learning algorithms and built a tissue classification model trained with dissected gastric tissues. A machine-learning-based spectro-histological model was built based on the autofluorescence spectra measured from stomach tissue samples with delineated and validated histological structures. The scores from a principal components analysis were employed as input features, and prediction accuracy was confirmed to be 92.0%, 90.1%, and 91.4% for mucosa, submucosa, and muscularis propria, respectively. We investigated the tissue samples in both sliced and block forms using a fast fluorescence imaging scanner. We successfully demonstrated differentiation of multiple tissue layers of well-defined specimens with the guidance of a histologist. Our spectro-histology classification model is applicable to histological prediction for both tissue blocks and slices, even though only sliced samples were trained.

Preclinical Studies in Vascularized Composite Allotransplantation

Introduction: Since 1998, when the first hand transplant was performed, Vascularized Composite Allotransplantation (VCA) field represents a new dimension in reconstructive surgery, offering a viable treatment option for injuries and defects that involve multiple layers of functional tissue, impossible to repair using conventional surgical techniques. Worldwide experience includes allotransplantation of upper and lower extremities, face, trachea, larynx, abdominal wall, uterus and penis, with promising clinical results. The major challenge remains at the immunologic level, translational ongoing studies being focused to develop less toxic immunosuppressant drugs and possibly achieve donor-specific tolerance. Materials and Methods: We conducted a series of preclinical studies of vascularized composite allotransplantation in preparation for further translation to clinical applications of this field. Our experience includes experimental vascularized allotransplantation models in rats exploring technical particularities and also analyzing the role of microchimerism in immunomodulation and promoting of the immune tolerance. Also, we performed a cadaveric study in order to explore the surgical techniques required in abdominal wall allotransplantation and the use of iliac crest as a potential microsurgical model of vascularized bone marrow transplantation(VBMT). Results: Working on small animal models allows the familiarization with microsurgical techniques in experimental composite tissue allotransplantation and evaluation of important immunological aspects: rejection dynamics, immunosuppression protocol testing and induction of immunologic tolerance. The surgical procedures performed in cadaveric models shown the feasibility of the abdominal wall allotransplantation procedure which may be translated to future clinical practice in association with organ transplantation. It may be possible to develop an alternative approach for iliac crest microsurgical transplant as tolerogenic strategy in solid organs or vascularized composite allotransplantation. Conclusion: Preclinical experience represents a mandatory step in developing a vascularized composite allotransplantation program, translating the knowledge obtained from experimental animal research and cadaveric studies to further clinical practice, ensuring optimal results for patients with complex tissue defects.

GSDMD deficiency ameliorates hyperoxia-induced BPD and ROP in neonatal mice

Bronchopulmonary dysplasia (BPD) and retinopathy of prematurity (ROP) are among the most common morbidities affecting extremely premature infants who receive oxygen therapy. Many clinical studies indicate that BPD is associated with advanced ROP. However, the mechanistic link between hyperoxia, BPD, and ROP remains to be explored. Gasdermin D (GSDMD) is a key executor of inflammasome-induced pyroptosis and inflammation. Inhibition of GSDMD has been shown to attenuate hyperoxia-induced BPD and brain injury in neonatal mice. The objective of this study was to further define the mechanistic roles of GSDMD in the pathogenesis of hyperoxia-induced BPD and ROP in mouse models. Here we show that global GSDMD knockout (GSDMD-KO) protects against hyperoxia-induced BPD by reducing macrophage infiltration, improving alveolarization and vascular development, and decreasing cell death. In addition, GSDMD deficiency prevented hyperoxia-induced ROP by reducing vasoobliteration and neovascularization, improving thinning of multiple retinal tissue layers, and decreasing microglial activation. RNA sequencing analyses of lungs and retinas showed that similar genes, including those from inflammatory, cell death, tissue remodeling, and tissue and vascular developmental signaling pathways, were induced by hyperoxia and impacted by GSDMD-KO in both models. These data highlight the importance of GSDMD in the pathogenesis of BPD and ROP and suggest that targeting GSDMD may be beneficial in preventing and treating BPD and ROP in premature infants.

Layer thickness prediction and tissue classification in two-layered tissue structures using diffuse reflectance spectroscopy

During oncological surgery, it can be challenging to identify the tumor and establish adequate resection margins. This study proposes a new two-layer approach in which diffuse reflectance spectroscopy (DRS) is used to predict the top layer thickness and classify the layers in two-layered phantom and animal tissue. Using wavelet-based and peak-based DRS spectral features, the proposed method could predict the top layer thickness with an accuracy of up to 0.35 mm. In addition, the tissue types of the first and second layers were classified with an accuracy of 0.95 and 0.99. Distinguishing multiple tissue layers during spectral analyses results in a better understanding of more complex tissue structures encountered in surgical practice.

Lumbar Skin Lesion in a Term Infant.

Lumbar Skin Lesion in a Term Infant.

On the correlations of biomechanical properties of super-imposed temporal tissue layers and their age-, sex-, side- and post-mortem interval dependence

Obtaining biomechanical properties of biological tissues for simulation purposes or graft developments is time and resource consuming. The number of samples required for biomechanical tests could be reduced if the load-deformation properties of a given tissue layer could be estimated from adjacent layers or if the biomechanical parameters were unaffected by age, bodyside, sex or post-mortem interval. This study investigates for the first time potential correlations of multiple super-imposed tissue layers using the temporal region of the human head as an area of broad interest in biomechanical modelling. Spearman correlations between biomechanical properties of the scalp, muscle fascia, muscle, bone and dura mater from up to 83 chemically unfixed cadavers were investigated. The association with age, sex and post-mortem interval was assessed. The results revealed sporadic correlations between the corresponding layers, such as the maximum force (r = 0.43) and ultimate tensile strength (r = 0.33) between scalp and muscle. Side- and age-dependence of the biomechanical properties were different between the tissue types. Strain at maximum force of fascia (r = -0.37) and elastic modulus of temporal muscle (r = 0.26) weakly correlated with post-mortem interval. Only strain at maximum force of scalp differed significantly between sexes. Uniaxial biomechanical properties of individual head tissue layers can thus not be estimated solely based on adjacent layers. Therefore, correlations between the tissues’ biomechanical properties, anthropometric data and post-mortem interval need to be established independently for each layer. Sex seems not to be a relevant influencing factor for the passive tissue mechanics of the here investigated temporal head tissue layers.

126 Lipidomic analysis of tissue layers in healthy skin

The skin consists of multiple tissue layers harboring distinct compartments of lipid metabolism. Because of limitations in separating and homogenizing skin tissue layers and given technological advances in mass spectrometry, there is a need for precise dissection of the microanatomy of skin combined with quantitative assessment of lipid distribution by employing state of the art technology. The aim of this project is to analyze lipid profiles by Liquid Chromatography - Mass Spectrometry (LC-MS) to detect lipid alterations in healthy skin.

Dispersion profile of a needle-free jet injection depends on the interfacial property of the medium.

Injections into or through the skin are common drug or vaccine administration routes, which can be achieved with conventional needles, microneedles, or needle-free jet injections (NFJI). Understanding the transport mechanism of these injected fluids is critical for the development of effective drug administration devices. NFJI devices are distinct from traditional injection techniques by their route and time scale, which relies on a propelled microjet with sufficient energy to penetrate the skin surface and deliver the drug into the targeted region. The injected fluid interacts with multiple skin tissue layers and interfaces, which implies that the corresponding injection profile is dependent on their mechanical properties. In this study, we address the lack of fundamental knowledge on the impact of these interfaces on the injection profiles of NFJI devices.

Multiphysics modelling of photon, mass and heat transfer in coral microenvironments.

Coral reefs are constructed by calcifying coral animals that engage in a symbiosis with dinoflagellate microalgae harboured in their tissue. The symbiosis takes place in the presence of steep and dynamic gradients of light, temperature and chemical species that are affected by the structural and optical properties of the coral and their interaction with incident irradiance and water flow. Microenvironmental analyses have enabled quantification of such gradients and bulk coral tissue and skeleton optical properties, but the multi-layered nature of corals and its implications for the optical, thermal and chemical microenvironment remains to be studied in more detail. Here, we present a multiphysics modelling approach, where three-dimensional Monte Carlo simulations of the light field in a simple coral slab morphology with multiple tissue layers were used as input for modelling the heat dissipation and photosynthetic oxygen production driven by photon absorption. By coupling photon, heat and mass transfer, the model predicts light, temperature and O2 gradients in the coral tissue and skeleton, under environmental conditions simulating, for example, tissue contraction/expansion, symbiont loss via coral bleaching or different distributions of coral host pigments. The model reveals basic structure–function mechanisms that shape the microenvironment and ecophysiology of the coral symbiosis in response to environmental change.

Skin Quality - A Holistic 360° View: Consensus Results.

IntroductionSkin quality is an important component of human attractiveness. To date, there are no standardized criteria for good skin quality. To establish a consensus for good skin quality parameters and measurement and treatment options, a virtual skin quality advisory board consisting of a global panel of highly experienced aesthetic dermatologists/aesthetic physicians was convened.MethodsA total of 10 dermatologists/aesthetic physicians served on the advisory board. A modified version of the Delphi method was used to arrive at consensus. Members accessed an online platform to review statements on skin quality criteria from their peers, including treatment and measurement options, and voted to indicate whether they agreed or disagreed. Statements that did not have agreement were modified and the members voted again. Consensus was defined as: strong consensus = greater than 95% agreement; consensus = 75% to 95% agreement; majority consent = 50% to 75% agreement; no consensus = less than 50% agreement.ResultsThere was strong consensus that good skin quality is defined as healthy, youthful in appearance (appearing younger than a person’s chronological age), undamaged skin and that skin quality can be described across all ethnicities by four emergent perceptual categories (EPCs): skin tone evenness, skin surface evenness, skin firmness, and skin glow. The EPCs can be affected by multiple tissue layers (ie, skin surface quality can stem from and be impacted by deep structures or tissues). This means that topical approaches may not be sufficient. Instead, improving skin quality EPCs can require a multilayer treatment strategy.ConclusionThis global advisory board established strong consensus that skin quality can be described by four EPCs, which can help clinicians determine the appropriate treatment option(s) and the tissue or skin layer(s) to address. Skin quality is important to human health and wellbeing and patients’ perception for the need for aesthetic treatment.

An x-ray microanalytical method for measuring in vivo element and water concentrations, relating to osmoregulation, in cells and tissues of the posterior eye.

Osmoregulation is critical for cell and tissue survival yet there are relatively few methods available to determine osmotic gradients from water and elemental concentration either in single cells or across multiple cellular layers of tissue. X-ray microanalysis of frozen-hydrated preparations in a scanning electron microscope is one such powerful, sensitive, nondestructive technique. Here we use x-ray microanalysis to quantitatively analyse intracellular element concentrations and oxygen concentrations, as a proxy for water concentrations, in selected individual cells of the posterior eye. Using frozen-hydrated preparations of the retinal complex of chicken eyes, it is shown that structural preservation is sufficient to identify cell layers and individual cells. The quantitative analysis of selected areas in the photoreceptor layer, inner nuclear layer and ganglion cell layer, where specific cell types were known to be present, provided measurements of intracellular element concentrations comparable with the analysis of individual cells. It is also shown that in the cells of the retinal pigment epithelium and outer photoreceptor segments elemental analyses were reasonably consistent at the cellular level in different depth levels of the same sample. Comparison of oxygen concentrations, as a proxy for water concentration, at two accelerating voltages (15 and 5 kV) indicated that at 15 kV oxygen concentration was largely derived from intracellular water. Water concentrations could be calculated and concentrations of diffusible elements (Na, K) could be defined in mmol/L. From the latter it is possible to calculate osmotic concentrations of individual cells and osmotic gradients across the tissue. LAY DESCRIPTION: Understanding many cellular processes, in both healthy and diseased states, depends on knowing how the water content of cells and their surrounding fluids is controlled. The transport of water is generally down its concentration gradient or against the osmotic concentration gradient defined by solutes such as sodium, potassium and chloride dissolved in the water. We have refined a microanalytical method, that detects the x-rays emitted from specific elements when they are bombarded by electrons in a scanning electron microscope, to apply it to the analysis of the retina of the eye. The method facilitates the measurement of the elemental composition, water and osmotic concentration gradients of cells and tissues in the eye, that may be involved in the development of myopia, or short sightedness, a condition that afflicts many people including some 80 - 90% of children in Asia.

Impact of the mechanical properties of penetrated media on the injection characteristics of needle-free jet injection

Needle-free jet injection systems are characterized by the increased drug delivery efficacy over conventional needle-based injection systems and have become a viable alternative. The majority of previous studies have investigated underlying mechanisms of needle-free jet injection systems with an emphasis on the fluid dynamics of the propelled microjet without considering the influence of an injected medium on the penetration and dispersion of the microjet. Unlike the injected fluid introduced directly into a target region of the skin tissue through a hollow needle, the fluid microjet produced by a needle-free injector has to work through multiple skin tissue layers and interfaces having different mechanical properties. Here we evaluated injection characteristics in two hydrogel media having similar stiffness controlled precisely but different pore size and hence different fracture toughness. High-speed imaging data showed that the fracture toughness of the medium influenced the penetration mechanism of the injected microjet, whereas viscoelastic and poroelastic characteristics of the medium determined the final attainable injection profiles. The injection profiles were also dependent on the type and depth of the interface between the layers of two media, where tight and loose interfaces can have different effects on the distribution of injected drug as the injected fluid prefers the path having the least resistance. Our findings would improve the present understanding of needle-free jet injection systems and could help to develop more effective drug delivery systems.

Benthic cyanobacteria of the genus Nostoc are a source of microcystins in Greenlandic lakes and ponds

Abstract Benthic primary producers are recognised for their important role in contributing to ecosystem productivity and nutrient cycling in lake and stream ecosystems, particularly in polar environments. In Arctic lakes, benthic producers often comprise mats or colonies of cyanobacteria capable of producing cyanotoxins. However, the extent to which benthic communities contribute cyanotoxins in polar regions remains poorly described. We evaluated the potential for benthic colonies of the cyanobacterium Nostoc pruniforme from lakes in Kangerlussuaq, Greenland, to contribute microcystins (MCs) to lake water using three approaches. First, we dissected field‐collected Nostoc colonies and measured MCs within multiple layers of fresh colony tissue. Second, we conducted a laboratory experiment to evaluate the temporal dynamics of MC release by incubated, intact colonies. Finally, we quantified whether MC concentrations in water and sediment samples in the field were higher in and above dense bands of benthic Nostoc as compared to bare sediment. Field‐collected Nostoc colonies contained MCs throughout the colony tissue, suggesting that damage to colonies from grazers or physical disturbance could facilitate the release of toxins into the water. Undamaged Nostoc colonies incubated in high‐nutrient conditions in the laboratory leaked MCs into the surrounding water at a steady mass‐specific rate over the course of 7 days. Microcystin concentrations in water and sediment from two Greenlandic lakes were highly variable, but slightly higher in lake water immediately above dense bands of Nostoc than in water immediately above bare sediments, suggesting that benthic Nostoc colonies contribute cyanotoxins to lake water and that MCs vary at very fine, 1–2 m spatial scales. Benthic cyanobacteria may be important in releasing MCs into aquatic ecosystems, especially in systems where benthic producers dominate, such as polar environments.

Polycaprolactone-based dermal filler complications: A retrospective study of 1111 treatments.

BackgroundAging signs can be corrected through volume restoration in multiple soft tissue layers and in the supraperiosteal plane using hyaluronic acid (HA) or nonhyaluronic acid (non‐HA) fillers. The non‐HA bioresorbable polycaprolactone (PCL)‐based filler with collagen‐stimulating properties has a proven safety profile, but rare potential complications such as nodules and granuloma can occur. Furthermore, PCL‐based fillers cannot be immediately removed by injection of an enzyme. These potential drawbacks have yet to be described in the literature.AimsThe author performed 1111 treatments between 2015 and 2018. This study aims to review and analyze these treatments to ascertain the complication rates of the PCL‐based filler. Suggestions for complication prevention and management are also discussed.Methods780 patients treated with the PCL‐based filler were reviewed by the physician between April 2015 and May 2018. During this period, 5595 syringes were used in 1111 treatments. All complication data were acquired by phone interviews, reports by patients, or observation at follow‐up visits. Complications were subdivided into early‐onset (occurring up to 2 weeks after treatment) and late‐onset events (occurring more than 2 weeks to years after treatment).ResultsAmong the 1111 treatments, there were 50 cases (4.5%) of edema that lasted longer than 2 weeks, 30 cases (2.7%) of bruising, 8 cases (0.72%) of malar edema, 5 cases (0.45%) of temporarily palpable lumps and 2 cases (0.18%) of discoloration. There were no cases of intravascular injection, nodules/granulomas, or infection.ConclusionThe complication rate of the PCL‐based filler was found to be low, and there were no cases of intravascular injection, nodules, and/or granulomas during the 3‐year observation. Longer‐lasting edema was associated with a higher injection volume and malar edema was related to lymphatic compression.

Extracellular single-unit recordings from peripheral nerve axons in vitro by a novel multichannel microelectrode array

The peripheral nervous system (PNS) is an attractive target for modulation of afferent input (e.g., nociceptive input signaling tissue damage) to the central nervous system. To advance mechanistic understanding of PNS neural encoding and modulation requires single-unit recordings from individual peripheral neurons or axons. This is challenged by multiple connective tissue layers surrounding peripheral nerve fibers that prevent electrical recordings by existing electrodes or electrode arrays. In this study, we developed a novel microelectrode array (MEA) via silicon-based microfabrication that consists of 5 parallel hydrophilic gold electrodes surrounded by silanized hydrophobic surfaces. This novel hydrophilic/hydrophobic surface pattern guides the peripheral nerve filaments to self-align towards the hydrophilic electrodes, which dramatically reduces the technical challenges in conducting single-unit recordings. We validated our MEA by recording simultaneous single-unit action potentials from individual axons in mouse sciatic nerves, including both myelinated A-fibers and unmyelinated C-fibers. We confirmed that our recordings were single units from individual axons by increasing nerve trunk electrical stimulus intensity, which did not alter the spike shape or amplitude. By reducing the technical challenges, our novel MEA will likely allow peripheral single-unit recordings to be adopted by a larger research community and thus expedite our mechanistic understanding of peripheral neural encoding and modulation.

Pulsed Field Ablation Versus Radiofrequency Ablation: Esophageal Injury in a Novel Porcine Model.

Pulsed field ablation (PFA) can be myocardium selective, potentially sparing the esophagus during left atrial ablation. In an in vivo porcine esophageal injury model, we compared the effects of newer biphasic PFA with radiofrequency ablation (RFA). In 10 animals, under general anesthesia, the lower esophagus was deflected toward the inferior vena cava using an esophageal deviation balloon, and ablation was performed from within the inferior vena cava at areas of esophageal contact. Four discrete esophageal sites were targeted in each animal: 6 animals received 8 PFA applications/site (2 kV, multispline catheter), and 4 animals received 6 clusters of irrigated RFA applications (30 W×30 seconds, 3.5 mm catheter). All animals were survived to 25 days, sacrificed, and the esophagus submitted for pathological examination, including 10 discrete histological sections/esophagus. The animals weight increased by 13.7±6.2% and 6.8±6.3% (P=0.343) in the PFA and RFA cohorts, respectively. No PFA animals (0 of 6, 0%) developed abnormal in-life observations, but 1 of 4 RFA animals (25%) developed fever and dyspnea. On necropsy, no PFA animals (0 of 6, 0%) demonstrated esophageal lesions. In contrast, esophageal injury occurred in all RFA animals (4 of 4, 100%; P=0.005): a mean of 1.5 mucosal lesions/animal (length, -21.8±8.9 mm; width, -4.9±1.4 mm) were observed, including one esophago-pulmonary fistula and deep esophageal ulcers in the other animals. Histological examination demonstrated tissue necrosis surrounded by acute and chronic inflammation and fibrosis. The necrotic RFA lesions involved multiple esophageal tissue layers with evidence of arteriolar medial thickening and fibrosis of periesophageal nerves. Abscess formation and full-thickness esophageal wall disruptions were seen in areas of perforation/fistula. In this novel porcine model of esophageal injury, biphasic PFA induced no chronic histopathologic esophageal changes, while RFA demonstrated a spectrum of esophageal lesions including fistula and deep esophageal ulcers and abscesses.