In-vivo Porcine Model Research Articles

217 Comparison of the Histopathological Effects of Two Electrosurgical Currents in an In-Vivo Porcine Model of Esophageal Endoscopic Mucosal Resection

Stenosis is the main limitation of endoscopic resection (ER) in the esophagus. The optimal electrosurgical current (ESC) for ER in the esophagus and other gastrointestinal sites is presently unknown. There may be a relationship between the type of ESC used and the likelihood of post ER esophageal stricture (PERES) formation. Unlike low power coagulating current (LPCC), microprocessor controlled alternating short pulse cutting with coagulating current (MCC) avoids high peak voltages that are thought to result in deep thermal injury.

Sa1636 Electrosurgical Resection Currents and Their Histopathological Effects in an In-Vivo Porcine Model of Endoscopic Mucosal Resection.

Endoscopic Mucosal Resection (EMR) is now a well-established and effective method for the management of sessile polyps and laterally spreading tumours (LSTs). The majority of endoscopists use either a microprocessor controlled current, or a low power forced coagulation current to perform EMR. Microprocessor controlled currents limit voltage based on tissue resistance and fractionate cutting bursts. This is proposed to limit deep mural injury, whereas non-microprocessor controlled forced currents may be at higher risk of injury as the application of thermal energy is not limited or controlled.

Sa1580 Argon Plasma Coagulation Compared With snare Tip Soft Coagulation in an In-Vivo Porcine Model of Endoscopic Mucosal Resection

Endoscopic Mucosal Resection (EMR) is now a well-established and effective method for the management of sessile polyps and laterally spreading tumours (LSTs). There are few studies of adjunctive thermal therapies such as argon plasma coagulation (APC) and snare tip soft coagulation (STSC) for the ablation of marginal defect tissue. Small studies examining APC have shown that recurrence may be variably reduced, but criticisms of APC include that it is poorly controllable, that the ablation depth varies, and that it may leave patchy areas of residual mucosa explaining the recurrence that occurs despite treatment.

In-vivo waveguide cardiac magnetic resonance elastography

Background Myocardial stiffness (MS) is elevated in heart failure with preserved ejection fraction(HFPEF)[1]. In addition, stiffness elevation in HFPEF exhibits directional dependency [2]. Conventional determinants of MS such as pressurevolume relationship and mechanical testing are invasive and hence clinically inefficient. Therefore, there is a need to non-invasively estimate anisotropic MS to assist in diagnosis and prognosis of HFPEF. In this study we implement waveguide cardiac magnetic resonance elastography (CMRE)[3] to demonstrate the feasibility of estimating anisotropic MS non-invasively in an in-vivo porcine model.

Endoscopic band ligation for closure of GI perforations in a porcine animal model (with video)

GI perforations occur rarely during endoscopy but have life-threatening implications. To evaluate endoscopic band ligation (EBL) for closure of acute GI perforations by using a porcine model. Investigator-initiated interventional pilot study by using an invivo porcine model. Tertiary-care institution. Ten domestic pigs. Each animal underwent a single endoscopic procedure, with creation of a single GI lumen perforation. Perforations of 10 to 20mm were created in the esophagus, stomach, duodenum, and colon. EBL was used for closure. Fourteen days later, the pigs were killed, microbial cultures were obtained, and histologic review was done. Immediate and delayed endoscopic closure of the perforation site, evidence of clinical peritonitis during the 14-day follow-up. Ten pigs completed the protocol and survived without clinical peritonitis during the 14-day follow-up. Endoscopic closure of a 15-mm esophageal perforation failed, thus, no attempt was made to close a 20-mm esophageal perforation. Closure of all other perforations was successful. At necropsy, fibrinous peritonitis was suspected in one animal with a 10-mm duodenal perforation. Chronic inflammation and fibroplasia at the perforation sites were the most common histologic findings. The applicability of widespread use in humans remains unknown despite successful case reports in the medical literature. EBL can be used successfully to close 10 to 20mm perforations within normal stomach, duodenum, and colon and can prevent clinically relevant intra-abdominal infections. However, for esophageal perforations, closure may be limited to small (≤10mm), iatrogenic perforations.

Potential of Magnetic Resonance-guided Focused Ultrasound for Intracranial Hemorrhage: An In Vivo Feasibility Study

Because of the paucity of effective treatments for intracranial hemorrhage (ICH), the mortality rate remains at 40%-60%. A novel application of magnetic resonance-guided focused ultrasound (MRgFUS) for ICH may offer an alternative noninvasive treatment through the precise delivery of FUS under real-time MR imaging (MRI) guidance. The purpose of the present study was to optimize the parameters for rapid, effective, and safe trans-skull large clot liquefaction using invivo porcine and exvivo human skull models to provide a clinically relevant proof of concept. The transcranial effectiveness of MRgFUS was tested exvivo by introducing a porcine blood clot into a human skull, without introducing tissue plasminogen activator (tPA). We used an experimental human head device to deliver pulsed FUS sonications at an acoustic power of 600-900W for 5-10seconds. A 3-mL clot was also introduced in a porcine brain and sonicated invivo with one 5-second pulse of 700W through a bone window or with 3000W when treated through an exvivo human skull. Treatment targeting was guided by MRI, and the tissue temperature was monitored online. Liquefied volumes were measured as hyperintense regions on T2-weighted MR images. In both invivo porcine blood clot through a craniectomy model and the porcine clot in an exvivo human skull model targeted clot liquefaction was achieved, with only marginal increase in temperature in the surrounding tissue. Our results demonstrate the feasibility of fast, efficient, and safe thrombolysis in an invivo porcine model of ICH and in 2 exvivo models using a human skull, without introducing tPA. Future studies will further optimize parameters and assess the nature of sonication-mediated versus natural clot lysis, the risk of rebleeding, the potential effect on the adjacent parenchyma, and the chemical and toxicity profiles of resulting lysate particles.

PD37-02 THE USE OF A REVERSE THERMOSENSITIVE POLYMER FOR URETEROSCOPY WITH LASER LITHOTRIPSY IN AN IN-VIVO PORCINE MODEL: ARE THERE ADVANTAGES BEYOND PREVENTION OF STONE RETROPULSION?

You have accessJournal of UrologyStone Disease: New Technology II1 Apr 2014PD37-02 THE USE OF A REVERSE THERMOSENSITIVE POLYMER FOR URETEROSCOPY WITH LASER LITHOTRIPSY IN AN IN-VIVO PORCINE MODEL: ARE THERE ADVANTAGES BEYOND PREVENTION OF STONE RETROPULSION? Jonathan Mobley, Goutham Vemana, Marshall Strother, R. Sherburne Figenshau, Jeff Larson, and Brian Benway Jonathan MobleyJonathan Mobley More articles by this author , Goutham VemanaGoutham Vemana More articles by this author , Marshall StrotherMarshall Strother More articles by this author , R. Sherburne FigenshauR. Sherburne Figenshau More articles by this author , Jeff LarsonJeff Larson More articles by this author , and Brian BenwayBrian Benway More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2014.02.2020AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES To evaluate the effects of a reverse thermosensitive polymer (RTP) during ureteroscopy with laser lithotripsy (URSL) in an in-vivo porcine model. METHODS Six pigs underwent general anesthesia followed by bilateral URSL of stone phantoms while measuring intrapelvic renal pressures through bilateral nephrostomy tubes. The procedures were performed in one ureter with the RTP and in the contralateral, control ureter without the RTP. Stone migration lengths, operative times, laser times, laser energy usage, intrapelvic pressures, and post-necropsy histological examinations of the ureters were compared between the two groups. RESULTS Bilateral URSL was successfully performed in 5/6 pigs. In one pig, only the unilateral control was performed, because the ureter was too narrow to complete the contralateral side. The mean laser time was 12.8 minutes shorter with the use of the RTP group than in the controls (p=0.021). The procedure time, laser energy usage, and retropulsion length was shorter in the RTP group, but did not reach significance. Between the two groups, there was no difference in mean renal pelvic pressures, peak renal pelvic pressures, or post-procedure histological examinations of the ureters. CONCLUSIONS The use of a RTP during URSL may have greater advantages beyond preventing stone retropulsion. Here, the use of a RTP during URSL resulted in a significant decrease in laser times. Further clinical investigations could further delineate the advantages of using a RTP during URSL. Table 1. Effects of RTP on Ureteroscopy with Laser Lithotripsy Procedures Control RTP p value Procedure Time (min) 29.0 ± 3.86 24.8 ± 3.15 0.421 Laser Time (min) 28.0 ± 3.84 15.2 ± 2.18 0.021 RTP Time (min) N/A 9.6 ± 2.25 N/A Laser Energy (KJ) 2.95 ± 0.35 2.20 ± 0.28 0.134 Retropulsion Length (cm) 4.17 ± 1.25 1.8 ± 0.66 0.136 Baseline RP Pressure (mmHg) 15.4 ± 2.45 13.2 ± 1.58 0.474 Average RP Pressure (mmHg) 21.0 ± 2.33 18.0 ± 2.58 0.410 Peak RP Pressure (mmHg) 41.2 ± 4.33 35.0 ± 5.91 0.425 Abbreviations: RTP, reverse themosensitive polymer; KJ, Kilojoule; RP, renal pelvic, N/A, Not applicable © 2014FiguresReferencesRelatedDetails Volume 191Issue 4SApril 2014Page: e946 Advertisement Copyright & Permissions© 2014MetricsAuthor Information Jonathan Mobley More articles by this author Goutham Vemana More articles by this author Marshall Strother More articles by this author R. Sherburne Figenshau More articles by this author Jeff Larson More articles by this author Brian Benway More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Sa1542 Evolving Role of Endoscopic Ultrasound Before Surgery After Medical Down-Staging of Pancreaticobiliary Cancers

has been already applied as a minimally invasive, palliative therapy in hepatic and thyroid lesions. In a previous study we assessed the feasibility of EUS Nd: YAG LA on normal pancreatic tissue performed in-vivo in a porcine model. Aims: to confirm the feasibility and to evaluate the safety and the efficacy of EUS Nd:YAG LA on normal pancreatic tissue of in-vivo porcine model. Material and Methods: Six healthy farm swines, weighted 40-50 Kg, underwent pancreas LA under EUS control during general anaesthesia. Pancreatic gland was punctured with a 19-gauge needle through transgastric approach. A 1.064-nm wavelenght Nd:YAG laser was used. Output power of 2 and 3 W with a total delivered energy of 1000 J was supplied in continuous mode, as used in our previous pilot study. Serum levels of amylase, lipase and transaminase were obtained at baseline, after three hours of the endoscopic treatment, and before the euthanizing of the animals. After the endoscopic treatment the animals were observed for clinical signs of pancreatitis (loss of appetite, altered consciousness and irritability). After 1 month the animals were sedated and then euthanized by i.v. injection of pento-barbital (100mg/Kg). The EUS-LA target organ was excised and placed in formalin. Histological examination of the specimens was performed by a single pathologist. Results: All pancreatic specimens showed histological signs of coagulative necrosis. The ablation volume ranged from a mean of 357 to 590 mm3. No histochemical signs of pancreatitis were found at pathologic examination. All the pigs survived at 1 month. During the follow-up no pigs showed clinical signs of pancreatitis and biochemical parameters were normal. No other complications were detected at necropsy. Conclusions: EUSguided Nd:YAG LA of pancreas performed in vivo in a porcine model is feasible and safe. Nd:YAG laser creates a time-dependent ablation volume. Furthermore other studies are needed to apply this mini-invasive approach to human pancreatic lesions.

OC.04.2 DIAGNOSTIC ACCURACY OF RECTAL ENDOSCOPIC ULTRASONOGRAPHY TO DIAGNOSE DEEP PELVIC ENDOMETRIOSIS: EXPERIENCE FROM TWO REFERRAL GASTROENTEROLOGY UNITS

Background and aim: Intraoperatory radiofrequency ablation (RFA) of pancreas cancer has <8% complication rate.The ultrasound (EUS)-guided laser ablation might reduce risk because it is less invasive and able to discriminate the intervening vessels. Laser ablation (LA) performed with a neodymium:yttrium-aluminum garnet (Nd:YAG) laser can achieve a high rate of complete tissue necrosis and has been applied as a minimally invasive, palliative therapy in hepatic and thyroid lesions. In a previous study we assessed the feasibility of EUS Nd:YAG LA on normal pancreatic tissue performed in-vivo in a porcine model. Aims is to confirm the feasibility and to evaluate the safety and the efficacy of EUS Nd:YAG LA on normal pancreatic tissue of in-vivo porcine model. Material and methods: Six healthy farm swines, weighted 40-50 kg, underwent pancreas LA under EUS control during general anaesthesia. Pancreatic gland was punctured with a 19-gauge needle through transgastric approach. A 1.064-nm wavelenght Nd:YAG laser was used. Output power of 2 and 3 W with a total delivered energy of 1000 J was supplied in continuous mode, as used in our previous pilot study. Serum levels of amylase, lipase and transaminase were obtained at baseline, after three hours of the endoscopic treatment, and before the euthanizing of the animals. After the endoscopic treatment the animals were observed for clinical signs of pancreatitis (loss of appetite, altered consciousness and irritability). After 1 month the animals were sedated and then euthanized. The EUS-LA target organ was excised and placed in formalin. Histological examination of the specimens was performed by a single pathologist. Results: All pancreatic specimens showed histological signs of coagulative necrosis. The ablation volume ranged from a mean of 357 to 590 mm3. No histochemical signs of pancreatitis were found at pathologic examination. All the pigs survived at 1 month. During the follow-up no pigs showed clinical signs of pancreatitis and biochemical parameters were normal. No other complications were detected at necropsy. Conclusions: EUS-guided Nd:YAG LA of pancreas performed in vivo in a porcine model is feasible and safe. Nd:YAG laser creates a time-dependent ablation volume. Furthermore other studies are needed to apply this mini-invasive approach to human pancreatic lesions. OC.04.2

Non-invasive vesicoureteral reflux detection: Heating risk studies for a new device

Objective To investigate a novel non-invasive device developed to warm bladder urine and to measure kidney temperature to detect vesicoureteral reflux. Materials and methods Microwave antennas focused energy within the bladder. Phantom experiments measured the results. The heating protocol was optimized in an in-vivo porcine model, and then tested once, twice and three times consecutively in three pigs followed by pathologic examinations. Results Computer simulations showed a dual concentric conductor square slot antenna to be the best. Phantom studies revealed that this antenna easily heated a bladder phantom without over heating intervening layers. In-vivo a bladder heating protocol of 3 min with 30 W each to two adjacent antennas 45 s on 15 s off followed by 15 min of 15 s on and 45 s off was sufficient. When pigs were heated once, twice and three times with this heating protocol, pathologic examination of all tissues in the heated area showed no thermal changes. More intensive heating in the animal may have resulted in damage to muscle fibers in the anterior abdominal wall. Conclusions Selective warming of bladder urine was successfully demonstrated in phantom and animals. Localized heating for this novel vesicoureteral reflux device requires low-power levels and should be safe for humans.

Can Tasers® directly cause ventricular fibrillation?

Tasers are battery powered electrical devices used by law enforcement personnel to temporarily incapacitate suspects. This study is part of a larger study to determine the probability of a Taser (X26 and M26) causing ventricular fibrillation (VF) in humans. We determined the distance between a Taser dart and the ventricle (dart-to-heart distance) necessary to trigger VF in an in-vivo porcine model, using 6 anesthetized pigs. All experiments were approved by the appropriate IUCUC and adhere to all applicable laws and standards of the NIH and USDA as well as the policies of the APS. To more accurately represent the dart-to-heart distances found in a human, we reflected the skin, subcutaneous fat and muscle over the sternum and placed a thoracic dart into the third intercostal space over the right ventricle. Current flowed to a second dart 54 cm away on the abdomen. We determined that the distance between the darts makes no significant difference in the current. We confirmed dart location post mortem. In 6 pigs, VF was triggered at a mean dart-to-heart distance of 15 mm (0 – 20). We will combine these data with echocardiographic human anatomic data, police-provided dart landing distribution data, and a finite element method (FEM) model of current density in the human torso to yield a probability of a Taser causing VF in a human. This project was supported by Grant No. 2004-IJ-CX-K036 awarded by the National Institute of Justice, Office of Justice Programs, US Department of Justice. Points of view in this document are those of the authors and do not necessarily represent the official position or policies of the US Department of Justice.