Tissue Charring Research Articles

Comparison of transseptal puncture using a dedicated RF wire versus a mechanical needle with and without electrification in an animal model.

Mechanical force to achieve transseptal puncture (TSP) using a standard needle may lead to overshooting and injury, and can potentially be avoided using a radiofrequency (RF)-powered needle or wire. Applying electrocautery to needles and guidewires as an alternative to purpose-built RF systems has been associated with safety risks, such as tissue coring and thermal damage. The commercially available AcQCross needle-dilator system (Medtronic) features a sharp open-ended needle for mechanical puncture, as well as a built-in connector to enable energy delivery for RF puncture. This investigation compares the safety and efficacy of the AcQCross needle to the dedicated VersaCross RF wire system and generator (Baylis Medical/Boston Scientific). In an ex vivo porcine model, VersaCross wire punctures were performed using 1 s, constant mode (approx. 10 W) with maximum two attempts. AcQCross punctures were performed by applying energy for 2 s using a standard electrosurgical generator at 10 W (max. five attempts), 20 W (max. two attempts), and 30 W (max. two attempts). Efficacy was assessed in terms of puncture success and a number of energy applications required for TSP. Safety was assessed quantitatively as force required for TSP, energy required to puncture, and incidence of tissue coring, as well as by qualitative assessment of puncture sites. Additional qualitative observation of tissue cores and debris were obtained from TSP performed in live swine. RF TSP was 100% successful using the VersaCross wire with 1.0 ± 0.0 attempts. When power was used with the AcQCross needle, it failed to puncture at low (10 and 20 W) power settings; TSP was achieved with 30 W of energy with 91% success using 1.53 ± 0.51 attempts (p < .05 vs. VC) with greater variability (F1,33 = 9223.5, p < .0001). Compared to RF puncture using the VersaCross system, mechanical puncture, alone, using the AcQcross needle required six times more force (8 mm additional forward device displacement) to perforate the septum. Qualitative assessment of puncture sites revealed larger defects and more tissue charring with the AcQCross needle at 30 W compared to punctures with VersaCross wire. Tissue coring with the open-ended AcQCross needle was observed in vivo and measured to occur in 57% of punctures using the ex vivo model; no coring was observed with the closed-tip VersaCross wire. The AcQCross needle frequently required higher energy of 30 W to achieve RF TSP and was associated with tissue coring and charring, which have been, previously, reported when electrifying a standard open-ended mechanical needle or guidewire. These findings may limit safety and effectiveness compared to the VersaCross system.

Role of Platelet Rich Fibrin Matrix in Management of Electric Burns

Electric burns injury is a problem which is still found now a days. The wound ranges from mild blistering to full thickness charring of tissues, when the wound goes into the healing phase there is difficulty due to the nature of the burns and the large area it involves. Any problem with the edge of the wound can be detrimental to healing and may cause delay in wound healing. In this article, we share our experience of using Platelet Rich Fibrin (PRF) for wound bed preparation in electric burns wound healing.

Machine Learning Approach in Optimal Localization of Tumor Using a Novel SIW-Based Antenna for Improvement of Ablation Zone in Hepatocellular Carcinoma

In recent years, hepatocellular carcinoma has been the leading cause of cancer-related mortality and thermal ablation procedures such as MWA (microwave ablation) and RFA (Radiofrequency ablation) provide a viable alternative to radiation and surgical excision. Due to uneven ablation and tissue charring in RFA, MWA offers faster and uniform heating as a result of its higher operating frequency. In MWA, the antenna probe heats the tissue to the point of cell necrosis using electromagnetic heating. In this aspect, a substrate-integrated waveguide (SIW) antenna is designed to work at 2.45 GHz. Further, a finite element method (FEM) is employed to model the probe and the liver tissue environment. Within 10 minutes of application time, a maximum ablation diameter of 32 mm (transversal-T) and 25 mm (axial-A) is achieved at 20W of power. Since the position of the applicator probe is of utmost importance, the relationship between the percentage of ablation, probe tip position, and tumor diameter is evaluated using ML- algorithm to estimate the ideal probe location for maximal tumor ablation and thus may improve clinical outcome.

A Novel Laser Energy Ablation Catheter for Endocardial Cavo-Tricuspid Isthmus Ablation and Epicardial Ventricular Lesion Formation: An in vivo Proof-of-Concept Study.

AimThis proof-of-concept study aimed to investigate atrial and ventricular lesion formation by a 20-mm linear laser ablation catheter, regarding lesion depth and tissue damage.MethodsIn total, 6 female swines underwent standard femoral vein access to introduce a novel 20-mm linear laser ablation catheter in the right atrium to perform endocardial cavotricuspid isthmus (CTI) ablations. The navigation took place under fluoroscopy with additional visualization by intracardiac echocardiograph. Via a sternotomy, epicardial ablations were performed on the surface of the left ventricle (LV), right ventricle (RV), and right atrial appendage (RAA). Procedural safety was assessed by registration of intraprocedural adverse events and by macroscopic examination of the excised hearts for the presence of charring or tissue disruption at the lesion site.ResultsAltogether 39 lesions were created, including 8 endocardial CTI (mean lesion length 20.6 ± 1.65 mm), 26 epicardial ventricle (mean lesion length LV: 25.3 ± 1.35 mm, RV: 24.9 ± 2.40 mm), and 5 epicardial appendage ablations (mean lesion length RAA: 26.0 ± 3.16 mm). Transmurality was achieved in all CTI and atrial appendage ablations, in 62% of the RV ablations and in none of the LV ablations. No perforation or steam pop occurred, and no animal died during the procedure.ConclusionIn this porcine study, the 20-mm linear laser ablation catheter has shown excellent results for endocardial cavotricuspid isthmus ablation, and it resulted in acceptable lesion depth during atrial and ventricular epicardial ablation. The absence of tissue charring, steam pops, or microbubbles under the experimental conditions suggests a high degree of procedural safety.

Comparing the safety and effectiveness of dedicated radiofrequency transseptal wires to electrified metal guidewires.

BackgroundApplication of electrocautery to a metal guidewire is used by some operators to perform transseptal puncture (TSP). Commercially available dedicated radiofrequency (RF) guidewires may represent a better alternative. This study compares the safety and effectiveness of electrified guidewires to a dedicated RF wire.MethodsTSP was performed on freshly excised porcine hearts using an electrified 0.014″ or 0.032″ guidewire under various power settings and was compared to TSP using a dedicated RF wire with 5 W power (0.035″ VersaCross RF System, Baylis Medical). The primary endpoint was the number of attempts required to achieve TSP. Secondary endpoints included the rate of TSP failure, TSP consistency, the effect of the distance between the tip of the guidewire and the tip of the dilator, and effect of RF power output level. Qualitative secondary endpoints included tissue puncture defect appearance, thermal damage to the TSP guidewire or dilator, and tissue temperature using thermal imaging.ResultsThe RF wire required on average 1.10 ± 0.47 attempts to cross the septum. The 0.014″ electrified guidewire required an overall mean of 2.17 ± 2.36 attempts (2.0 times as many as the RF wire; p < .01), and the 0.032″ electrified guidewire required an overall mean of 3.90 ± 2.93 attempts (3.5 times as many as the RF wire; p < .01). Electrified guidewires had a higher rate of TSP failure, and caused larger defects and more tissue charring than the RF wire. Thermal analysis showed higher temperatures and a larger area of tissue heating with electrified guidewires than the RF wire.ConclusionFewer RF applications were required to achieve TSP using a dedicated RF wire compared to an electrified guidewire. Smaller defects and lower tissue temperatures were also observed using the RF wire. Electrified guidewires required greater energy delivery and were associated with equipment damage and tissue charring, which may present a risk of thrombus, thermal injury, or scarring.

Liver Parenchymal Transection Through Radiofrequency Ablation Using a Radial Probe: Technical Report of a New Modality.

Various techniques have been reported to reduce blood loss during a parenchymal transection, and the radiofrequency ablation (RFA) technique is one of them. Owing to the charring of the adjacent liver tissue and the inability to use the conventional RFA techniques near major vessels, this study used a radial fiber of RFA. This technical report thus describes a technique to perform parenchymal transection using a radial fiber as well as its advantages and disadvantages. A radial fiber dissipates the energy radially and it has the added advantage of placing along the same and perpendicular axis of the liver parenchyma; it has been used in three patients in this study. The total intraoperative blood loss was 30-50 ml during parenchymal transection, and the intraoperative duration was 120-170 min. Bile leak was noted in one patient, which was then managed using the conventional treatment. Through the present technique, the fiber can be used in the vicinity of major blood vessels and necrosis and charring can be prevented. Although radial fiber has some advantages, it remains in the preliminary stage and requires further validation.

Comparisons between impedance-based and time-based switching bipolar radiofrequency ablation for the treatment of liver cancer

Switching bipolar radiofrequency ablation (bRFA) is a cancer treatment technique that activates multiple pairs of electrodes alternately based on a predefined criterion. Various criteria can be used to trigger the switch, such as time (ablation duration) and tissue impedance. In a recent study on time-based switching bRFA, it was determined that a shorter switch interval could produce better treatment outcome than when a longer switch interval was used, which reduces tissue charring and roll-off induced cooling. In this study, it was hypothesized that a more efficacious bRFA treatment can be attained by employing impedance-based switching. This is because ablation per pair can be maximized since there will be no interruption to RF energy delivery until roll-off occurs. This was investigated using a two-compartment 3D computational model. Results showed that impedance-based switching bRFA outperformed time-based switching when the switch interval of the latter is 100 s or higher. When compared to the time-based switching with switch interval of 50 s, the impedance-based model is inferior. It remains to be investigated whether the impedance-based protocol is better than the time-based protocol for a switch interval of 50 s due to the inverse relationship between ablation and treatment efficacies. It was suggested that the choice of impedance-based or time-based switching could ultimately be patient-dependent.

Basic laser procedures in orthodontic practice

Adding a soft tissue laser to an orthodontist's technology toolbox permits performance of numerous procedures that reduce time in treatment, saves valuable chair time and improves results. It is critical to know both the abilities and limitations of the device in order to maximize benefits to both patient and practice, and realize an acceptable return on investment. Important considerations to understand when treatment planning for a laser procedure include the type of laser to use, levels of keratinized tissue, an understanding of biologic width and measurement of pocket depth. It is also critical to use the proper settings on the laser to reduce tissue charring, which could potentially result in delayed healing and postoperative discomfort. The most critical criterion when purchasing a laser may well be the amount and type of training that comes with the device. Within these parameters, a number of procedures may be safely and easily performed by orthodontists including gingivectomies, tooth exposures, frenotomies (labial and lingual), crestal fiberotomies and treatment of aphthous ulcers.

Comparison of tonsillectomy by coblation and tonsillectomy by conventional method

&lt;p class="abstract"&gt;&lt;strong&gt;Background:&lt;/strong&gt; Operations on tonsils and adenoids are performed since many years. Tonsillectomy produces an open wound that heals by secondary intention. Tonsillectomy is still a very common surgical procedure. There are various modalities to perform surgery (diathermy, laser, harmonic scalpel, radiofrequency cautery, cryosurgery and coblation). Among these, dissection and snare method are commonly done by ENT surgeons.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Methods:&lt;/strong&gt; We carried out the prospective cross-sectional study to compare intraoperative blood loss, time taken for the surgery, post-operative pain score, degree of slough formation and complications between these two methods. &lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Results:&lt;/strong&gt; Average time for surgery on coblation side was less (15.1 min) than conventional side (36.04 min). For haemostasis on conventional side, all patients required bipolar cauterization while on coblation side only 8 patients (16%) required hemostasis. Average blood loss on coblation side (left) was 3.40ml while on conventional side (right) 25.57 ml. In my study, mean pain score on 1st day, 2&lt;sup&gt;nd&lt;/sup&gt; day, 5&lt;sup&gt;th&lt;/sup&gt; and 10&lt;sup&gt;th&lt;/sup&gt; day of surgery was 6.18, 4.10, 2.30 and 1.64 on conventional side and 4.36, 3.00, 1 and 0 on coblation side. In my study, only one patient had Secondary haemorrhage on conventional side on 7&lt;sup&gt;th&lt;/sup&gt; day.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Conclusions:&lt;/strong&gt; The use of coblator reduces the time required for surgery, per-operative blood loss is very much less, chances of damage to surrounding structures are less, charring of tissue is less, post-operative severity of pain after 24 hours is very much less than that of dissection method. Slough formation was more on coblation side as compared to conventional side.&lt;/p&gt;

Safety and effectiveness of a novel generator algorithm for bipolar vessel sealing: a randomised controlled chronic animal study

BackgroundElectrosurgical vessel sealers are gradually replacing conventional techniques such as ligation and clipping. Algorithms that control electrosurgical units (ESU), known as modes, are important for applications in different surgical disciplines. This chronic porcine animal study aimed to evaluate the safety and effectiveness of the novel thermoSEAL electrosurgical vessel sealing mode (TSM). The BiClamp® mode (BCM) of the renowned VIO® 300 D ESU served as control. BCM has been widely available since 2002 and has since been successfully used in many surgical disciplines. The TSM, for the novel VIO® 3 ESU, was developed to reduce sealing time and/or thermal lateral spread adjacent to the seal while maintaining clinical success rates. The primary aim of this study was to investigate the long-term and intraoperative seal quality of TSM.MethodsThe BiCision® device was used for vessel sealing with TSM and BCM in ten German Landrace pigs which underwent splenectomy and unilateral nephrectomy during the first intervention of the study. The seals were cut with the BiCision® knife. Ninety-nine arteries, veins and vascular bundles were chronically sealed for 5 or 21 days. Thereafter, during the second and terminal intervention of the study, 97 additional arteries and veins were sealed. The carotid arteries were used for histological evaluation of thermal spread.ResultsAfter each survival period, no long-term complications occurred with either mode. The intraoperative seal failure rates, i.e. vessel leaking or residual blood flow after the first sealing activation, were 2% with TSM versus 6% with BCM (p = 0.28). The sealing time was significantly shorter with TSM (3.5 ± 0.69 s vs. 7.3 ± 1.3 s, p < 0.0001). The thermal spread and burst pressure of arteries sealed with both modes were similar (p = 0.18 and p = 0.61) and corresponded to the histological evaluation. The measured tissue sticking parameter was rare with both modes (p = 0.33). Tissue charring did not occur. Regarding the cut quality, 97% of the seals were severed in the first and 3% in the second attempt (both with TSM and BCM).ConclusionsThe novel TSM seals blood vessels twice as fast as the BCM while maintaining excellent tissue effect and clinical success rates.Trial registrationNot applicable.

Feasibility and Acute Safety Study of Radiofrequency Energy Delivery to the Vena Caval Wall via an IVC Filter in Swine.

Retrievable inferior vena cava (IVC) filters are self-expanding metallic devices implanted in the IVC to prevent migration of thrombi from the deep veins of the legs and pelvis to the lungs. The risk of complications from the filters increases with duration of implantation, but retrieval may be difficult due to intimal hyperplasia around the components of the filter. In this study, the potential for delivery of radiofrequency (RF) energy to the IVC wall via the filter was investigated. IVC filters were deployed in 4 swine while attached to a snare connected to a 480 kHz RF generator. Energy ranging from 0 to 48 kJ was applied via the filter followed by re-sheathing and withdrawal of the filter while connected to a force measurement device. Resheathing forces for the 0-energy cohort and pooled data from the 6-24 kJ cohorts were 4.50±0.70 N and 4.50±0.75 N, respectively. Petechial hemorrhages and variable non-occlusive thrombi were noted in some cohorts including the 0-energy cohort, consistent with delivery and acute retrieval of an IVC filter. Histologically, the extent of RF-induced injury was subtle at 6 kJ with focal areas of homogenized collagen while the 12 kJ cohort showed segmental tissue charring with coagulation necrosis which was more extensive for the 24 kJ cohort. The 48 kJ energy caused more extensive and non-target organ damage. The study demonstrated feasibility of delivery of RF to the IVC wall via a deployed filter, supporting further study of the ability of local RF heating of the IVC wall to inhibit the neointimal hyperplasia or as an aid in retrieval.

Robotic Assisted MRI-Guided Interventional Interstitial MR-Guided Focused Ultrasound Ablation in a Swine Model.

Ablative lesions are current treatments for epilepsy and brain tumors. Interstitial magnetic resonance (MR) guided focused ultrasound (iMRgFUS) may be an alternate ablation technique which limits thermal tissue charring as compared to laser therapy (LITT) and can produce larger ablation patterns nearer the surface than transcranial MR guided focused ultrasound (tcMRgFUS). To describe our experience with interstitial focused ultrasound (iFUS) ablations in swine, using MR-guided robotically assisted (MRgRA) delivery. In an initial 3 animals, we optimized the workflow of the robot in the MR suite and made modifications to the robotic arm to allow range of motion. Then, 6 farm pigs (4 acute, 2 survival) underwent 7 iMRgFUS ablations using MRgRA. We altered dosing to explore differences between thermal dosing in brain as compared to other tissues. Imaging was compared to gross examination. Our work culminated in adjustments to the MRgRA, iMRgFUS probes, and dosing, culminating in 2 survival surgeries; swine had ablations with no neurological sequelae at 2 wk postprocedure. Immediately following iMRgFUS therapy, diffusion-weighted imaging, and T1 weighted MR were accurate reflections of the ablation volume. T2 and fluid-attenuated inversion-recovery (FLAIR) images were accurate reflections of ablation volume 1-wk postprocedure. We successfully performed MRgRA iFUS ablation in swine and found intraoperative and postoperative imaging to correlate with histological examination. These data are useful to validate our system and to guide imaging follow-up for thermal ablation lesions in brain tissue from our therapy, tcMRgFUS, and LITT.

Monitoring of tissue optical properties during thermal coagulation of ex vivo tissues.

Real-time monitoring of tissue status during thermal ablation of tumors is critical to ensure complete destruction of tumor mass, while avoiding tissue charring and excessive damage to normal tissues. Currently, magnetic resonance thermometry (MRT), along with magnetic resonance imaging (MRI), is the most commonly used technique for monitoring and assessing thermal ablation process in soft tissues. MRT/MRI is very expensive, bulky, and often subject to motion artifacts. On the other hand, light propagation within tissue is sensitive to changes in tissue microstructure and physiology which could be used to directly quantify the extent of tissue damage. Furthermore, optical monitoring can be a portable, and cost-effective alternative for monitoring a thermal ablation process. The main objective of this study, is to establish a correlation between changes in tissue optical properties and the status of tissue coagulation/damage during heating of ex vivo tissues. A portable diffuse reflectance spectroscopy system and a side-firing fiber-optic probe were developed to study the absorption (μa (λ)), and reduced scattering coefficients (μ's (λ)) of native and coagulated ex vivo porcine, and chicken breast tissues. In the first experiment, both porcine and chicken breast tissues were heated at discrete temperature points between 24 and 140°C for 2 minutes. Diffuse reflectance spectra (430-630 nm) of native and coagulated tissues were recorded prior to, and post heating. In a second experiment, porcine tissue samples were heated at 70°C and diffuse reflectance spectra were recorded continuously during heating. The μa (λ) and μ's (λ) of the tissues were extracted from the measured diffuse reflectance spectra using an inverse Monte-Carlo model of diffuse reflectance. Tissue heating was stopped when the wavelength-averaged scattering plateaued. The wavelength-averaged optical properties, <μ's (λ)> and <μa (λ)>, for native porcine tissues (n = 66) at room temperature, were 5.4 ± 0.3 cm(-1) and 0.780 ± 0.008 cm(-1) (SD), respectively. The <μ's (λ)> and <μa (λ)> for native chicken breast tissues (n = 66) at room temperature, were 2.69 ± 0.08 cm(-1) and 0.29 ± 0.01 cm(-1) (SD), respectively. In the first experiment, the <μ's (λ)> of coagulated porcine and chicken breast tissue rose to 56.4 ± 3.6 cm(-1) at 68.7 ± 1.7°C (SD), and 52.8 ± 1 cm(-1) at 57.1 ± 1.5°C (SD), respectively. Correspondingly, the <μa (λ)> of coagulated porcine (140.6°C), and chicken breast tissues (130°C) were 0.75 ± 0.05 cm(-1) and 0.263 ± 0.004 cm(-1) (SD). For both tissues, charring was observed at temperatures above 80°C. During continuous monitoring of porcine tissue (with connective tissues) heating, the <μ's (λ)> started to rise rapidly from 13.7 ± 1.5 minutes and plateaued at 19 ± 2.5 (SD) minutes. The <μ's (λ)> plateaued at 11.7 ± 3 (SD) minutes for porcine tissue devoid of connective tissue between probe and tissue surface. No charring was observed during continuous monitoring of thermal ablation process. The changes in optical absorption and scattering properties can be continuously quantified, which could be used as a diagnostic biomarker for assessing tissue coagulation/damage during thermal ablation. Lasers Surg. Med. 48:686-694, 2016. © 2016 Wiley Periodicals, Inc.

Abstract 12271: Radiofrequency Ablation With Electrode in Contact With Circular Mapping Catheter: Coagulation, Char, and Pop Ocurrence Comparison With Two Types of Irrigated Ablation Catheters

Introduction: A circular mapping catheter (CMC, Biosense Webster Lasso® Catheter) is frequently used in radiofrequency (RF) ablation treatment of atrial fibrillation to aid in determining ablation targets, such as the pulmonary vein ostia. During RF delivery, the ablation electrode is often in close proximity and may sometimes be in contact with one of the electrodes of the CMC. In this study, we compare coagulation, tissue char, and pop occurrence for ablations in contact with a CMC electrode versus ablations without a CMC. Ablations were performed with open-irrigation ablation electrodes of the Biosense Webster ThermoCool® Catheter (6 hole) and ThermoCool® SF Catheter (56 hole). Hypothesis: There will be more coagulation formation when there is contact with CMC. Methods: The thigh muscles of 4 anesthetized pigs were exposed and a skin cradle created. A 6 hole or 56 hole catheter was placed on the muscle with 10g of force in perpendicular orientation. Some ablations were performed with the ablation catheter alone, while others were performed with a CMC resting on the thigh muscle and the ablation electrode contacting one of the CMC electrodes on top or on the side. Heparinized autologous blood (activated clotting time &gt; 350s) at 37°C was circulated in the thigh cradle at 275-300ml/min while ablations were performed at 50W for 60s with 30ml/min irrigation for 6 hole and 15ml/min for 56 hole. Pops during ablation were noted. After the ablation, the blood pool was removed while keeping the catheters in position, the ablation site was examined, and coagulation and tissue char was noted Results: See Table Conclusions: When comparing ablations with a CMC versus no CMC, there was more coagulation with a CMC. When comparing a 6 hole catheter with a CMC versus a 56 hole catheter with a CMC, there was more coagulation with the 6 hole ablation catheter. There was no significant difference in pop and tissue char in any comparison

Preparation of carbon-coated iron nanofluid and its application in radiofrequency ablation.

Carbon-coated iron nanoparticles (Fe@C CCINs) were synthesized by carbon arc discharge method and were studied via X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results showed that CCINs have good core-shell structure and are in size of 40-50 nm. Also, carbon-coated iron nanofluid (CCINs-nanofluid) was prepared via two-step method by dispersing as-prepared CCINs and polyvinylpyrrolidone (PVP) into physiological saline. Its dispersion stability and thermal conductivity were detected by gravity sedimentation method and Hotdisk thermal constant analyzer respectively. The results indicated that CCINs-nanofluid possesses good dispersity and stability. Moreover, CCINs-nanofluid showed enhanced thermal conductivity compared with its base fluid physiological saline. The enhancement of thermal conductivity even reaches 41%. Additionally, CCINs-nanofluid injection aided radiofrequency ablation (RFA) was carried out. The relation between tissue temperature and ablation time revealed that by injecting CCINs-nanofluid into pork livers during RFA, target tissue temperatures were less than 100°C. Dissected pork livers showed that there was little or no tissue charring around the ablation probe. Results of ablation area calculation showed that the ablation area of CCINs-nanofluid injection aided RFA was 67% larger than that of saline injection aided RFA, indicating that a larger-volume tumor tissue necrosis at a single session can be achieved by CCINs-nanofluid injection aided RFA.

Partial nephrectomy using radiofrequency incremental bipolar generator with multi electrode probe: experimental study in bench pig kidneys

BackgroundThe aim of this research project was the realization of an incremental bipolar radiofrequency generator with inline 4-electrode probe for partial renal resection without clamping of the vessels.MethodsThe experimentation was carried out across two phases: the preliminary realization of a specific generator and an inline multielectrode probe for open surgery (Phase 1); system testing on 27 bench kidneys for a total of 47 partial resection (Phase 2).The parameters evaluated were: power level, generator automatisms, parenchymal coagulation times, needle caliber, thickness of the coagulated tissue “slice”, charring, ergonomy, feasibility of the application of “bolster” stitches.ResultsThe analysis of the results referred to the homogeneity and thickness of coagulation, energy supply times with reference to the power level and caliber of the needles. The optimal results were obtained by using needles of 1.5 mm caliber at power level 5, and with coagulation times of 54 seconds for the first insertion and 30 seconds for the second.ConclusionsThe experimentation demonstrated that the apparatus, consisting of a generator named “LaparoNewPro” and fitted with a dedicated probe for open surgery, is able to carry out a coagulation of the line of resection of the renal parenchyma in a homogeneous manner, in short times, without tissue charring, and with the possibility of stitching both on coagulated tissue and the caliceal system.The generator automatism based on the flow of the current supplied by each electrode is reliable, and the cessation of energy supply coincides with optimal coagulation.

Radiofrequency lesioning through deep brain stimulation electrodes: A pilot study of lesion geometry and temperature characteristics

Deep brain stimulation (DBS) electrodes have been used effectively to perform radiofrequency lesions in the brain. This study aimed to characterize lesion geometry and peak tissue temperature achieved when lesioning through DBS electrodes. Fresh bovine liver was chosen for a medium as the tissue reliably changes color between 45 and 50°C. Medtronic 3387 DBS electrodes (Medtronic Sofamor Danek, Inc., Memphis, TN, USA) and the Cosman G4 Radiofrequency Generator (Cosman Medical, Inc., Burlington, MA, USA) were used for lesioning. Bipolar lesions were created at currents between 25mA and 100mA for 60–120seconds. Peak tissue temperature was monitored with Cosman disposable cordotomy electrode (LCED; Cosman Medical Inc.) and recorded. Photographic analysis of the lesions was performed. Tissue impedance ranged between 800–900Ohms, and tissue temperature was maintained at 20°C. With lesions at 25mA for up to 120seconds, maximal tissue temperature achieved was 36°C. This correlated with no visible lesions. At 50mA, maximal tissue temperature exceeded 100°C, which was associated with tissue charring. Lesions created at 35mA and 40mA led to an increase in tissue temperature of 63°C and 75°C, respectively. Lesion size was highly reproducible, increasing from 4.5mm×7mm at 35mA, to 6mm×7.5mm at 50mA. Preliminary analysis suggests that caution should be exerted in using lesion amplitudes exceeding 40mA (at 800Ohms), as peak tissue temperatures in vivo could exceed 100°C. Further in vivo experiments with imaging correlates are needed to further test the safety of this technique.

${\rm He}\hbox{-}{\rm H}_{2}{\rm O}_{2}$ Plasma Jet Irradiation of Tissue Surfaces: Study of Dominant Pathways For Plasma Chemical Tissue Removal

Surface tissue-removal mechanisms, resulting from atmospheric He-H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> plasma jet fluxes impinging on tissue surfaces, were investigated. We employed primarily optical emission for cataloging relative concentrations of reactive plasma radicals versus plasma-jet conditions. The reactive radicals were then correlated with measured tissue-removal rates, under varying experimental conditions to determine the dominant role of OH radicals in the tissue removal. Fourier transform infrared (FTIR) molecular spectroscopy was employed to track molecular bond alterations at tissue surfaces, following the plasma irradiation of tissue surfaces. We studied three types of samples: 1) volatilized tissue fragments, filtered out of the effluent; 2) remaining solid-phase tissue samples in the incision region; and 3) nonprocessed contiguous tissue-surface regions. All surface bondings were compared and contrasted by FTIR analysis. In parallel, both the pure electro surgery (ES) with no added plasma radical fluxes and plasma-assisted ES were used as a dual baseline. This three-part study provides evidence that OH radicals drive the observed changes on tissue surfaces both within, and in bordering tissue regions in a He-H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> atmospheric plasma jet. Moreover, plasma-assisted ES as compared to pure ES reduces buildup of tissue char on the ES device electrodes, which is a practical advantage in ES surgery. FTIR measurement of the surgical margins (surrounding the removed tissue) is possible in pure plasma-jet tissue removal, via measuring changes in amide A bonds, which are indicators of the level of thermal damage to surrounding tissue, and may be a possible control means to achieve minimum collateral damage.

Transurethral Resection of Bladder Cancer: A Simple and Diffusely-Performed Technique but with Controversial Outcomes

Nowadays TUR is considered the golden standard for the diagnosis and treatment of NMIBC. However, TUR should be adequate: all bladder lesions should be resected and muscle must be present in the specimen in order to correctly stage the tumor. No bladder perforation should be performed and CIS diagnosed. Bimanual palpation pre- and post-TUR should be encouraged, especially in teaching institutions. Urethroscopy should always precede the visualization of the bladder. All the visible tumors should be resected preferably with bipolar resectoscope, to avoid tissue charring and to facilitate the pathological diagnosis. The exophytic part of the tumor should be first resected and the fragment collected in a separate bottle. Tumor base must be biopsied with cold cup. Muscle must be present in the specimen. Fulguration of the tumor base and 1-2 cm around is of paramount importance. One of the most important parameters for evaluating the quality of TUR is tumor recurrence after 3 months. The EORTC GU Group showed that the 3-month recurrence varied from 0 to 46% between the European institutions participating in randomized prospective EORTC studies. This variability was not explained by the tumor characteristics nor by the adjuvant therapy administered, but by the poor quality of the TUR. The surgeon’s performance and poor TUR quality were therefore suggested as being responsible for the results. A second EORTC study confirmed in fact that using a bladder diagram at the moment of diagnosis (signing the areas where the lesions are) and the presence of an experienced surgeon performing TUR were the two significant factors that could reduce the recurrence after 3 months. A complete, adequate first TUR is of paramount importance for the outcome of patients with NMIBC. It could be more important than any further adjuvant therapy administered.

Histopathologic Changes After Bipolar Resection of the Prostate: Depth of Penetration of Bipolar Thermal Injury

While the power needed to initiate bipolar vaporization is higher than conventional monopolar resection, the energy needed to maintain bipolar vaporization is significantly lower and may result in less thermal tissue injury. This may have implications for hemostasis, scarring, and perioperative morbidity. The objective of this study is to assess histopathologic changes in prostatic tissue after bipolar transurethral vaporization of the prostate. Male patients older than 40 years with a diagnosis of benign prostatic hyperplasia (BPH) who elected to undergo bipolar transurethral vaporization of the prostate were included in this study. Patients were excluded if they had a previous transurethral resection of the prostate (TURP) or prostate radiation therapy. An Olympus button vaporization electrode was used to vaporize prostate tissue. A loop electrode was then used to obtain a deep resection specimen. The vaporized and loop resection surfaces were inked and sent for pathologic analysis to determine the presence of gross histologic changes and the depth of penetration of the bipolar vaporization current. A total of 12 men underwent bipolar TURP at standard settings of 290 W cutting and 145 W coagulation current. Mean patient age was 70±10.2 years (range 56-88 years). Mean surgical time was 48.7±20.2 minutes (range 30-89 min). Mean depth of thermal injury was 2.4±0.84 mm (range 0.3-3.5 mm). Histopathologic evaluation demonstrated thermal injury in all specimens, but no gross char was encountered. In bipolar systems, resection takes place at much lower peak voltages and temperatures compared with monopolar systems. Theoretically, this leads to less collateral thermal damage and tissue char. Our tissue study illustrates that the button vaporization electrode achieves a much larger depth of penetration than previous studies of bipolar TURP. This may be because thermal injury represents a gradual continuum of histologic changes.