In-vivo Porcine Model Research Articles

Change in renal blood flow in response to intrarenal pressure alterations induced by ureteroscopy in an in-vivo porcine model.

High irrigation rates are commonly used during ureteroscopy and can increase intrarenal pressure (IRP) substantially. Concerns have been raised that elevated IRP may diminish renal blood flow (RBF) and perfusion of the kidney. Our objective was to investigate the real-time changes in RBF while increasing IRP during Ureteroscopy (URS) in an in-vivo porcine model. Four renal units in two porcine subjects were used in this study, three experimental units and one control. For the experimental units, RBF was measured by placing an ultrasonic flow cuff around the renal artery, while performing ureteroscopy in the same kidney using a prototype ureteroscope with a pressure sensor at its tip. Irrigation was cycled between two rates to achieve targeted IRPs of 30mmHg and 100mmHg. A control data set was obtained by placing the ultrasonic flow cuff on the contralateral renal artery while performing ipsilateral URS. At high IRP, RBF was reduced in all three experimental trials by 10-20% but not in the control trial. The percentage change in RBF due to alteration in IRP was internally consistent in each porcine renal unit and independent of slower systemic variation in RBF encountered in both the experimental and control units. RBF decreased 10-20% when IRP was increased from 30 to 100mmHg during ureteroscopy in an in-vivo porcine model. While this reduction in RBF is unlikely to have an appreciable effect on tissue oxygenation, it may impact heat-sink capacity in vulnerable regions of the kidney.

MP68-04 IN-VIVO PORCINE INTRARENAL PRESSURE-IRRIGATION FLOW CHARACTERIZATION AT VARIOUS OUTLET RESISTANCES

You have accessJournal of UrologyCME1 Apr 2023MP68-04 IN-VIVO PORCINE INTRARENAL PRESSURE-IRRIGATION FLOW CHARACTERIZATION AT VARIOUS OUTLET RESISTANCES Ron Marom, Julie J. Dau, Marne M. Louters, Khurshid R. Ghani, Timothy L. Hall, and William W. Roberts Ron MaromRon Marom More articles by this author , Julie J. DauJulie J. Dau More articles by this author , Marne M. LoutersMarne M. Louters More articles by this author , Khurshid R. GhaniKhurshid R. Ghani More articles by this author , Timothy L. HallTimothy L. Hall More articles by this author , and William W. RobertsWilliam W. Roberts More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003331.04AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Modern ureteroscopy techniques sometimes necessitate rapid irrigation rates to manage visualization and mitigate temperature elevation during laser lithotripsy. However, faster irrigation rates can elevate intrarenal pressure (IRP) which might in turn cause pressure induced adverse effects (e.g., sepsis). In this study we sought to assess IRP as a function of irrigation rate at different outlet resistances in an in-vivo porcine model. METHODS: Ureteroscopy was performed in a porcine model with a prototype ureteroscope containing a pressure sensor at its tip. A modified Ureteral Access Sheath (mUAS) was configured to accommodate the ureteroscope and adjust outflow resistance. Four different resistant values from low to very high were utilized to simulate a range of outflow scenarios. These resistances were subsequently calculated to be 2.59, 3.78, 5.61, 10.34 (cmH2O/(ml/min)). The distal end of the ureteroscope was fixed inside the renal collecting system. For each outlet resistance steady state IRP was measured across a range of irrigation rates. Using MATLAB, the pressure/flow relationship was plotted, and a linear regression was calculated from the linear portion of the curve. RESULTS: Similar trends were seen with all four outflow resistances scenarios. At lower irrigation rates the pressure change in response to increased irrigation was gradual and nonlinear, likely reflecting a “compliant” phase of the renal collecting system. Once IRP reached ∼15 cmH2O, pressure increased in a linear fashion with irrigation rate, suggesting that the distensibility of the collecting system had become saturated. CONCLUSIONS: The relationship between outlet resistance and IRP is an important concept to understand when considering safe parameters to use in ureteroscopy. Knowledge of outflow resistance and the IRP response to increased irrigation rates may aid decision making regarding placement of a ureteral access sheath. Furthermore, the mUAS is an important tool for controlling outlet resistance in experimental biologic systems and ureteroscopic studies. Source of Funding: Boston Scientific © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e953 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Ron Marom More articles by this author Julie J. Dau More articles by this author Marne M. Louters More articles by this author Khurshid R. Ghani More articles by this author Timothy L. Hall More articles by this author William W. Roberts More articles by this author Expand All Advertisement PDF downloadLoading ...

MP68-17 IN-VIVO THERMAL SAFETY VALIDATION OF URETEROSCOPY LASER POWER – IRRIGATION RATE PARAMETER PAIRS

You have accessJournal of UrologyCME1 Apr 2023MP68-17 IN-VIVO THERMAL SAFETY VALIDATION OF URETEROSCOPY LASER POWER – IRRIGATION RATE PARAMETER PAIRS Ron Marom, Julie J. Dau, Khurshid R. Ghani, Timothy L. Hall, and William W. Roberts Ron MaromRon Marom More articles by this author , Julie J. DauJulie J. Dau More articles by this author , Khurshid R. GhaniKhurshid R. Ghani More articles by this author , Timothy L. HallTimothy L. Hall More articles by this author , and William W. RobertsWilliam W. Roberts More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003331.17AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: High-power laser lithotripsy settings improve stone ablation rate and treatment efficiency but also can induce elevated fluid temperatures to a point of toxic thermal dose. Previous in-vitro work mapped out safety boundaries based on laser power/irrigation rate pairs. Our objective in this study was to assess the thermal safety of a range of laser power settings at different irrigation rates in an in-vivo model. METHODS: Ureteroscopy was performed in an anesthetized in-vivo porcine model with a novel prototype ureteroscope containing a thermocouple sensor at its tip. The distal end of the ureteroscope was positioned in the middle of a small calyx and maintained there for the entire experiment. Three trials of 60 seconds laser activation were carried out at each selected power setting and irrigation rate. Using MATLAB, thermal dose was calculated from the time-temperature curves for each trial using the Sapareto and Dewey formula. The threshold of thermal tissue injury was considered to be 120 equivalent minutes. Laser power-irrigation rate parameter pairs were categorized based on number of trials that exceeded thermal dose and designated in the figure as red (Unsafe) – all trials exceeded threshold, yellow – some trials exceeded threshold, green (Safe) – no trials exceeded threshold. RESULTS: The collecting fluid temperature was increased with greater laser power and slower irrigation rate. The calculated thermal dose was above threshold for the power setting of 17.5 Watts and irrigation flow rate of 9 ml/min. With irrigation flow rates greater than 24 ml/min, none of the tested laser power settings (up to 48 Watts) exceeded the thermal dose threshold from 60 seconds of continuous laser activation. CONCLUSIONS: This study demonstrates a method to assess thermal safety of laser power-irrigation rate parameter pairs in an in-vivo porcine model. Building upon this foundation, other variables such as operator duty cycle and pedal activation time can be incorporated to more accurately replicate real-world patterns of clinical laser user. Additionally, the impact of mitigation strategies (higher irrigation flow rates, control of laser operator duty-cycle, limiting pedal activation time and use of chilled irrigation fluid) can be assessed with these standardized methods. Source of Funding: Boston Scientific © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e960 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Ron Marom More articles by this author Julie J. Dau More articles by this author Khurshid R. Ghani More articles by this author Timothy L. Hall More articles by this author William W. Roberts More articles by this author Expand All Advertisement PDF downloadLoading ...

Histotripsy of Subcutaneous Fat in a Live Porcine Model.

This study was designed to evaluate the feasibility and safety of histotripsy subcutaneous (SQ) fat treatment in an in-vivo porcine model, and evaluate evolution of the treated volume on MRI and pathology. 10 histotripsy SQ fat treatments were completed in 5 swine, divided into four groups based on pre-determined survival: day 0 (n = 4), day 7 (n = 2), day 28 (n = 2), and day 56 (n = 2). A 4.0 × 4.0x2.0cm ovoid treatment was created in the fat pad of the posterior thorax. MRI of survived animals were obtained on day 7 (n = 6), day 28 (n = 4), and day 56 (n = 2), and reviewed for size and imaging characteristics. Technical success was defined as the creation of a treatment zone in the targeted SQ fat. Skin firmness and indentation were qualitatively scored. Histotripsy had a 100% (10/10) technical success for creation of SQ fat treatments. Mean treatment time was 35.5min (range 35-36.5). The volume of treated SQ fat demonstrated 92% volume reduction over the study. Day 0 gross pathology treatment had a mean volume of 12.6 cm3 (± 2.1) (prescribed volume of 16.7cm3), which decreased to 8.3cm3 (± 2.8) by day 7 (34% overall decrease), 3.0cm3 (± 0.5) by day 28 (76% overall decrease), and 1.0cm3 (± 1.2) by day 56 (92% overall decrease). Mean firmness and indentation scores showed no change from baseline at all time points, with no overlying skin injury. Histotripsy safely and effectively treated SQ fat of an in-vivo porcine model, with volume reduction over time.

Abstract No. 330 Evaluation of reduced contrast dose reference vascular roadmaps in an in-vivo porcine model

Abstract No. 330 Evaluation of reduced contrast dose reference vascular roadmaps in an in-vivo porcine model

What is the impact of pulse modulation technology, laser settings and intraoperative irrigation conditions on the irrigation fluid temperature during flexible ureteroscopy? An in vivo experiment using artificial stones.

To investigate the effect of different combinations of laser power settings and irrigation conditions using the pulse modulation technology of Quanta™ on irrigation fluid temperature (IFT) during FURS (flexible ureteroscopy) on an in-vivo porcine model with artificial stones. A female pig was used. Following the insertion of artificial stones (Begostone™, BEGO USA, Lincoln, RI), a K-type thermocouple was fixed to the created percutaneous access tract. Real-time recordings of IFT during FURS were performed without UAS (ureteral access sheath), with 10/12 UAS, 12/14 UAS and 14/16 UAS. Stone fragmentation was achieved using Quanta Litho Cyber Ho 150W™ (Samarate, Italy). The IFT was recorded for 30s, during laser activation, with power settings of 20, 40, 60, 75 and 100W under both manual pump and gravity irrigation. The IFT rise above 54°C was recorded above a power of 40W when gravity irrigation was used. The use of UAS prolonged the time for IFT to reach high values, although high power settings increase IFT within seconds from the laser activation. Under pump irrigation, only the 100W power setting without the use of UAS resulted in dangerous IFT after approximately 10s. The high-power Ho:YAG laser can cause a damaging thermal effect to the kidney exceeding the threshold of 54°C, under gravity irrigation. Lower power settings (up to 40W) can be used with safety. According to our experiment, when using high power settings, the use of UAS and manual pump irrigation, is the safest combination regarding renal thermal damage.

In Vivo Porcine Aged Deep Vein Thrombosis Model for Testing Ultrasound-based Thrombolysis Techniques.

As blood clots age, many thrombolytic techniques become less effective. To fully evaluate these techniques for potential clinical use, a large animal aged-clot model is needed. Previous minimally invasive attempts to allow clots to age in an in vivo large animal model were unsuccessful because of the clot clearance associated with relatively high level of cardiac health of readily available research pigs. Prior models have thus subsequently used invasive surgical techniques with the associated morbidity, animal stress and cost. We propose a method for forming sub-acute venous blood clots in an in-vivo porcine model. The age of the clots can be controlled and varied. By using an intravenous scaffold to anchor the clot to the vessel wall during the aging process, we can show that sub-acute clots can consistently be formed with a minimally invasive, percutaneous approach. The clot formed in this study remained intact for at least 1 wk in all subjects. Therefore, we established a new minimally invasive, large animal aged-clot model for evaluation of thrombolytic techniques.

Developing an in-vivo physiological porcine model of inducing acute atraumatic compartment syndrome towards a non-invasive diagnosis using shear wave elastography

Compartment syndrome (CS) is a pathological event caused by elevated intracompartmental pressure (ICP); however, changes from the onset of inducing atraumatic CS remained unclear. The study aimed to investigate the physiological changes in a newly developed in vivo porcine acute atraumatic CS model. CS was induced by ischemia–reperfusion injury in the left hind leg of fourteen pigs divided into an echogenicity group (EG) and a shear wave elastography group (SEG). Echogenicity was measured in EG, and shear elastic modulus (SEM) was measured in SEG seven times before, at the onset of inducing CS, and every 30 min after the onset over eight hours. Simultaneously, ICP, blood pressure, and muscle perfusion pressure (MPP) were also measured in both groups. Our results indicate that SEM of the experimental leg in SEG significantly increased as CS developed compared to the control leg (p = 0.027), but no statistical difference in the echogenicity in EG was found between the experimental leg and control leg. There were also significant correlations between SEM and ICP (p < 0.001) and ICP and MPP (p < 0.001). Our method and findings can be a basis to develop a non-invasive diagnostic tool using a shear wave elastography for atraumatic CS.

V02-01 NEW TECHNOLOGIES IN ROBOT-ASSISTED KIDNEY TRANSPLANTATION: IMPROVING SURGICAL PERFORMANCES, EXPANDING THE INDICATION

V02-01 NEW TECHNOLOGIES IN ROBOT-ASSISTED KIDNEY TRANSPLANTATION: IMPROVING SURGICAL PERFORMANCES, EXPANDING THE INDICATION

Obsidian ASG® Autologous Platelet-Rich Fibrin Matrix and Colorectal Anastomotic Healing: A Preliminary Study

Introduction: Anastomotic leakage (AL) following colorectal resection is a devastating complication affecting morbidity, mortality, and quality of life of patients in the long term. Different tissue sealants and biologic glues were tested showing conflicting results regarding their influence on anastomotic healing and leak prevention. Application of autologous platelet-rich fibrin (Vivostat A/S, Alleroed, Denmark), which acts as a source of angiogenic growth factors and cytokines, showed promising results in an in-vivo porcine model. Herein, we present the first human study of stapled colorectal anastomoses supplemented with an autologous-derived platelet-rich fibrin matrix (Obsidian ASG®, Rivolution GmbH, Rosenheim, Germany and Vivostat A/S, Alleroed, Denmark). Materials and Methods: A retrospective analysis of prospectively accumulated data was performed in two colorectal centers (Linz, Vienna) on patients undergoing left-sided colorectal or coloanal stapled anastomosis between October 2018 and December 2019. The Obsidian ASG® Matrix was applied to the rectal stump, and after closure with the circular stapling device, at the circumference of anastomosis in every single case. Anastomoses were supplemented with intra- and extra-anastomotic application (IAA—intra-anastomotic application developed by Rivolution GmbH, Rosenheim, Germany) of Obsidian ASG® Matrix. The primary endpoints were incidence of perioperative complications and anastomotic leak rate. Results: Two-hundred-sixty-one (138 female) patients underwent left-sided colonic (n=177) or rectal resection (n=84). In 253 (96.9%) cases, a laparoscopic or robotic-assisted approach was used. There were no complications attributable to the intraoperative application of the Obsidian ASG® Matrix. All intraoperative leak tests were negative. Overall, anastomotic leak rate accounted for 2.3% (6/261). AL following colonic and rectal resection was seen in 2.3% (4/177) and 2.4% (2/84), respectively. Complication and leak rate was similar in the two participating centers. Postoperative fever and elevated CRP levels were significantly correlated to AL. There was no significant risk factor for AL on multivariate analysis. Conclusion: Application of an autologous-derived platelet-rich fibrin matrix (Obsidian ASG®) at anastomotic site following colorectal resection is safe and associated with a low rate of anastomotic leakage.

268 Smart polymer implants as an emerging technology for treating airway collapse in OSA: a proof of concept study

Abstract Introduction Implantable 3D printed ‘smart’ polymers are an emerging technology with potential applications in treating collapse in adult obstructive sleep apnea through mechanical airway manipulation. There is a paucity of devices that are commercially available or in research and development stage. Limited studies have investigated the use of implantable smart polymers in reversing the collapsibility of the pharyngeal airway by creating counter forces during sleep. This paper describes an application of implantable magnetic polymer technology in an in-vivo porcine model. Study Objectives: To assess the use of a novel magnetic polymer implant in reversing airway collapse and identifying potential anatomical targets for airway implant surgery in an in-vivo porcine model. Methods Target sites of airway collapse were genioglossus muscle, hyoid bone and middle constrictor. Magnetic polymer implants were sutured to these sites and external magnetic forces, through magnets with pull forces rated at 102kg and 294kg, were applied at the skin. The resultant airway movement was assessed via nasendoscopy. Pharyngeal plexus branches to the middle constrictor muscle were stimulated at 0.5mA, 1.0mA and 2.0mA and airway movement assessed via nasendoscopy. Results At the genioglossus muscles large magnetic forces were required to produce airway movement. At the hyoid bone, anterior movement of the airway was noted when using a 294kg rated magnet. At the middle constrictor muscle, an anterolateral (or rotatory) pattern of airway movement was noted when using the same magnet. Stimulation of pharyngeal plexus branches to the middle constrictor revealed contraction and increasing rigidity of the lateral walls of the airway as stimulation amplitude increased. The resultant effect was prevention of collapse, a previously unidentified pattern of airway movement. Conclusion Surgically implanted smart polymers are an emerging technology showing promise in the treatment of airway collapse in obstructive sleep apnea. Future research should investigate their biomechanical role as an adjunct to treatment of airway collapse through nerve stimulation. Support (if any) Garnett-Passe and Rodney Williams Memorial Foundation, Conjoint Grant, 2016-18.

Myocardial perfusion assessment in the infarct core and penumbra zones in an in-vivo porcine model of the acute, sub-acute, and chronic infarction.

To assess the longitudinal changes of microvascular function in different myocardial regions after myocardial infarction (MI) using myocardial blood flow derived by dynamic CT perfusion (CTP-MBF), and compare CTP-MBF with the results of cardiac magnetic resonance (CMR) and histopathology. The CTP scanning was performed in a MI porcine model 1 day (n = 15), 7 days (n = 10), and 3 months (n = 5) following induction surgery. CTP-MBF was measured in the infarcted myocardium, penumbra, and remote myocardium, respectively. CMR perfusion and histopathology were performed for validation. From baseline to follow-up scans, CTP-MBF presented a stepwise increase in the infarcted myocardium (68.51 ± 11.04 vs. 86.73 ± 13.32 vs. 109.53 ± 26.64 ml/100 ml/min, p = 0.001) and the penumbra (104.92 ± 29.29 vs. 120.32 ± 24.74 vs. 183.01 ± 57.98 ml/100 ml/min, p = 0.008), but not in the remote myocardium (150.05 ± 35.70 vs. 166.66 ± 38.17 vs. 195.36 ± 49.64 ml/100 ml/min, p = 0.120). The CTP-MBF correlated with max slope (r = 0.584, p < 0.001), max signal intensity (r = 0.357, p < 0.001), and time to max (r = - 0.378, p < 0.001) by CMR perfusion. Moreover, CTP-MBF defined the infarcted myocardium on triphenyl tetrazolium chloride staining (AUC: 0.810, p < 0.001) and correlated with microvascular density on CD31 staining (r = 0.561, p = 0.002). CTP-MBF could quantify the longitudinal changes of microvascular function in different regions of the post-MI myocardium, which demonstrates good agreement with contemporary CMR and histopathological findings. • The CT perfusion-based myocardial blood flow (CTP-MBF) could quantify the microvascular impairment in different myocardial regions after myocardial infarction (MI) and track its recovery over time. • The assessment of CTP-MBF is in good agreement with contemporary cardiac MRI and histopathological findings, which potentially facilitates a rapid approach for pathophysiological insights following MI.

Inhaled nitric oxide has pulmonary vasodilator efficacy both in the immediate and prolonged phase of acute pulmonary embolism.

Inhaled nitric oxide (iNO) effectively reduces right ventricular afterload when administered in the immediate phase of acute pulmonary embolism (PE) in preclinical animal models. In a porcine model of intermediate-risk PE, we aimed to investigate whether iNO has pulmonary vasodilator efficacy both in the immediate and prolonged phase of acute PE. Anesthetized pigs (n = 18) were randomized into three subgroups. An acute PE iNO-group (n = 6) received iNO at 40 ppm at one, three, six, nine and 12 hours after onset of PE. Vehicle animals (n = 6) received PE, but no active treatment. A third group of sham animals (n = 6) received neither PE nor treatment. Animals were evaluated using intravascular pressures, respiratory parameters, biochemistry and intracardiac pressure-volume measurements. The administration of PE increased mean pulmonary artery pressure (mPAP) (vehicle vs sham; 33.3 vs 17.7 mmHg, p < 0.0001), pulmonary vascular resistance (vehicle vs sham; 847.5 vs 82.0 dynes, p < 0.0001) and right ventricular arterial elastance (vehicle vs sham; 1.2 vs 0.2 mmHg/ml, p < 0.0001). Significant mPAP reduction by iNO was preserved at 12 hours after the onset of acute PE (vehicle vs iNO; 0.5 vs -3.5 mmHg, p < 0.0001). However, this response was attenuated over time (p = 0.0313). iNO did not affect the systemic circulation. iNO is a safe and effective pulmonary vasodilator both in the immediate and prolonged phase of acute PE in an in-vivo porcine model of intermediate-risk PE.

Right ventricular adaptation in the critical phase after acute intermediate-risk pulmonary embolism.

The haemodynamic response following acute, intermediate-risk pulmonary embolism is not well described. We aimed to describe the cardiovascular changes in the initial, critical phase 0-12 hours after acute pulmonary embolism in an in-vivo porcine model. Pigs were randomly allocated to pulmonary embolism (n = 6) or sham (n = 6). Pulmonary embolism was administered as autologous blood clots (20 × 1 cm) until doubling of mean pulmonary arterial pressure or mean pulmonary arterial pressure was greater than 34 mmHg. Sham animals received saline. Cardiopulmonary changes were evaluated for 12 hours after intervention by biventricular pressure-volume loop recordings, invasive pressure measurements, arterial and central venous blood gas analyses. Mean pulmonary arterial pressure increased (P < 0.0001) and stayed elevated for 12 hours in the pulmonary embolism group compared to sham. Pulmonary vascular resistance and right ventricular arterial elastance (right ventricular afterload) were increased in the first 11 and 6 hours, respectively, after pulmonary embolism (P < 0.01 for both) compared to sham. Right ventricular ejection fraction was reduced (P < 0.01) for 8 hours, whereas a near-significant reduction in right ventricular stroke volume was observed (P = 0.06) for 4 hours in the pulmonary embolism group compared to sham. Right ventricular ventriculo-arterial coupling was reduced (P < 0.05) for 6 hours following acute pulmonary embolism despite increased right ventricular mechanical work in the pulmonary embolism group (P < 0.01) suggesting right ventricular failure. In a porcine model of intermediate-risk pulmonary embolism, the increased right ventricular afterload caused initial right ventricular ventriculo-arterial uncoupling and dysfunction. After approximately 6 hours, the right ventricular afterload returned to pre-pulmonary embolism values and right ventricular function improved despite a sustained high pulmonary arterial pressure. These results suggest an initial critical and vulnerable phase of acute pulmonary embolism before haemodynamic adaptation.

Commentary on: Noninvasive Induction of Muscle Fiber Hypertrophy and Hyperplasia: Effects of High-Intensity Focused Electromagnetic Field Evaluated in an In-Vivo Porcine Model: A Pilot Study.

Commentary on: Noninvasive Induction of Muscle Fiber Hypertrophy and Hyperplasia: Effects of High-Intensity Focused Electromagnetic Field Evaluated in an In-Vivo Porcine Model: A Pilot Study.

Noninvasive Induction of Muscle Fiber Hypertrophy and Hyperplasia: Effects of High-Intensity Focused Electromagnetic Field Evaluated in an In-Vivo Porcine Model: A Pilot Study.

BackgroundHigh-intensity focused electromagnetic (HIFEM) field technology has been reported to increase muscle thickness and hypertrophy. However, this process has not yet been confirmed on a histologic level.ObjectivesThe aim of this study was to evaluate in-vivo structural changes in striated porcine muscle tissue following HIFEM treatment.MethodsThree Yorkshire pigs received four 30-minute HIFEM treatments applied to the biceps femoris muscle on 1 side only. The fourth pig served as a control subject. At baseline and 2 weeks after the last treatment, biopsy specimens of the muscle tissue were collected from the treatment site. The control pig underwent muscle biopsy from a similar but untreated site. Twenty-five histology slides were evaluated from each pig. A certified histopathologist analyzed sliced biopsy samples for structural changes in the tissue.ResultsHistologic analysis showed hypertrophic changes 2 weeks posttreatment. The muscle mass density increased by 20.56% (to a mean of 17,053.4 [5617.9] µm2) compared with baseline. Similarly, muscle fiber density (hyperplasia) increased: the average change in the number of fibers in a slice area of 136,533.3 µm2 was +8.0%. The mean size of an individual muscle fiber increased by 12.15% (to 332.23 [280.2] µm2) 2 weeks posttreatment. Control samples did not show any significant change in fiber density or hyperplasia.ConclusionsHistopathologic quantification showed significant structural muscle changes through a combination of fiber hypertrophy and hyperplasia. Control biopsies showed a lack of similar changes. The data correlate with findings of other HIFEM research and suggest that HIFEM could be used for noninvasive induction of muscle growth.

Su1341 USEFULNESS OF THE FLEXIBLE TRACTION METHOD IN GASTRIC ENDOSCOPIC SUBMUCOSAL DISSECTION: AN IN-VIVO ANIMAL STUDY

Endoscopic submucosal dissection (ESD) is considered to be useful as a minimally-invasive endoluminal surgery for possible node-negative early cancers, although it is technically demanding and time-consuming. Various tips to overcome difficulties in submucosal dissection have been proposed. Particularly, an appropriate traction of the target lesion is a key for a safe and secure procedure. We proposed the flexible traction (F-trac) method which provided an optimal traction using an endoscopic hand suturing (EHS) technique. In this study, we investigated usefulness of the F-trac method in gastric ESD in an in-vivo porcine model.

Rebamipide solution: a novel submucosal injection material to promote healing speed and healing quality of ulcers induced by endoscopic submucosal dissection

Rebamipide is administered perorally to protect the gastric mucosa. We assessed the efficacy and safety of a novel rebamipide solution as a submucosal injection material for endoscopic submucosal dissection (ESD) using an invivo porcine model. An endoscopist blinded to the test agents performed ESDs of hypothetical 30mm lesions using a 2% rebamipide solution at 2 sites (rebamipide group) and a saline solution at 2 other sites (control group) in the stomachs of 8 pigs. The technical outcomes were compared between the 2 groups. The gastric ulcer stages were evaluated by endoscopy once weekly for 4 weeks after the ESD to determine the healing score (1-6). The pigs were killed at 1 week (n= 2), 2 weeks (n= 2), and 4 weeks (n= 4) after the ESD for pathologic evaluation of ESD-induced ulcers and scarring. There were no significant differences in any of the technical outcomes between the 2 groups, and no adverse events related to the ESD in any of the animals. The healing score was significantly higher in the rebamipide group than in the control group at 2 weeks (P= .027), 3 weeks (P= .034), and 4 weeks (P= .012). In the histopathologic assessment, fibrosis was significantly less extensive in the rebamipide group than in the control group at 2 weeks (P= .02) and 4 weeks (P= .04). The rebamipide solution appeared to promote both the speed and quality of healing of ESD-induced ulcers by suppressing fibrosis.

In Vivo Porcine Model of Venous Air Embolism During Pars Plana Vitrectomy

Venous air embolism (VAE) during pars plana vitrectomy (PPV) can occur owing to improper positioning of the infusion cannula in the suprachoroidal space and may lead to sudden compromise of cardiac circulation and death. This was an invivo demonstration of fatal VAE during PPV to show that air can travel from the suprachoroidal space into the central circulation. Experimental invivo surgical study on porcine eyes. Experimental PPV under general anesthesia was performed on porcine eyes (Yorkshire species) at a University Surgical Training & Education Center. Infusion cannulas were placed into the suprachoroidal space and fluid-air exchange (FAE) was started with sequential increases in infusion air pressure. Vital signs of porcine animals were continuously monitored and recorded in real time during the PPV, including end-tidal carbon dioxide (ETCO2), oxygen saturation (SaO2), intra-arterial blood pressure, electrocardiography (EKG), and transesophageal echocardiography (TEE). Intracardiac air was detected on TEE less than 30 seconds after increasing air infusion pressure to 60mm Hg. ETCO2 declined precipitously, followed by hypotension and EKG changes. Oxygen desaturation was a late phenomenon. The animal died within 7minutes of VAE. During autopsy, the heart was open under water and air escaped from the right ventricle. This invivo porcine model confirms that during the FAE in PPV, pressurized air from an infusion cannula malpositioned in the suprachoroidal space can transit through the eye to the central circulation, resulting in fatal VAE.

Preliminary Evidence Suggests Periureteral Botulinum Toxin Type A Injection Improves Ureteral Stone Passage in the Porcine Model.

We evaluated the use of periureteral injection of botulinum toxin type A (Botox(®), BTX-A) to facilitate passage of ureteral stones in a porcine model. We believe that reducing detrusor muscle tone around the intramural ureter may facilitate passage of ureteral stones through the ureterovesical junction. With complete Institutional Animal Care and Use Committee approval, artificial stones (BegoStone plus) were placed by retrograde ureteroscopy into the proximal ureter using fluoroscopic guidance using an in-vivo porcine model. Six animals underwent periureteral BTX-A injection 30 U/mL to three locations around the ureteral orifice, and six animals were in the control group undergoing periureteral injection of physiologic saline. There was a significant decrease in time to stone passage in the BTX-A group compared with the control group, 2.6 ± 1.3 vs 6.8 ± 2.9 days, respectively (p = 0.018). None of the animals had evidence of vesicoureteral reflux postprocedure (N = 0/12). Preliminary results suggest that periureteral injection of BTX-A facilitates ureteral stone passage in this model. BTX-A may provide a simple, office-based endoscopic treatment option for ureteral stones. Further studies would be necessary to evaluate its efficacy in humans compared with traditional medical expulsive therapy.