Suchergebnisse

Radiofrequency (RF) catheter ablation is a minimally invasive medical procedure used to thermally destroy the focus of cardiac arrhythmias. Novel optical techniques are now being integrated into RF catheters in order to detect the changes in tissue properties. Loss of birefringence due to fiber denaturation at around 70ºC is related to changes in accumulated phase retardation and can be measured by polarization-sensitive optical coherence reflectometry (PS-OCR). Since irreversible thermal lesions are produced when the tissue reaches 50ºC, our goal was to seek the mathematical relationship between both isotherms. ; This work was partially supported by the Spanish Government under the "Plan Estatal de Investigación,Desarrollo e Innovación Orientada a los Retos de la Sociedad" Grant "TEC2014-52383-C3 (TEC2014-52383-C3-1-R)". A. González-Suárez has a Postdoctoral Grant"Juan de la Cierva-formación" (FJCI-2015-27202) sup-ported by the Spanish Ministerio de Economía, Industria yCompetitividad. This study was partially presented at the 2017 Annual Meeting of the American Society for LaserMedicine and Surgery. A. González-Suárez received atravel grant from the United States Air Force Office of Scientific Research.

10 pages, 8 figures, 2 tables and 1 additional file. ; [Background] Efficient and safe transection of biological tissue in liver surgery is strongly dependent on the ability to address both parenchymal division and hemostasis simultaneously. In addition to the conventional clamp crushing or finger fracture methods other techniques based on radiofrequency (RF) currents have been extensively employed to reduce intraoperative blood loss. In this paper we present our broad research plan for a new RF-assisted device for bloodless, rapid resection of the liver. ; [Methods] Our research plan includes computer modeling and in vivo studies. Computer modeling was based on the Finite Element Method (FEM) and allowed us to estimate the distribution of electrical power deposited in the tissue, along with assessing the effect of the characteristics of the device on the temperature profiles. Studies based on in vivo pig liver models provided a comparison of the performance of the new device with other techniques (saline-linked technology) currently employed in clinical practice. Finally, the plan includes a pilot clinical trial, in which both the new device and the accessory equipment are seen to comply with all safety requirements. ; [Results] The FEM results showed a high electrical gradient around the tip of the blade, responsible for the maximal increase of temperature at that point, where temperature reached 100°C in only 3.85 s. Other hot points with lower temperatures were located at the proximal edge of the device. Additional simulations with an electrically insulated blade produced more uniform and larger lesions (assessed as the 55°C isotherm) than the electrically conducting blade. The in vivo study, in turn, showed greater transection speed (3 ± 0 and 3 ± 1 cm2/min for the new device in the open and laparoscopic approaches respectively) and also lower blood loss (70 ± 74 and 26 ± 34 mL) during transection of the liver, as compared to saline-linked technology (2 ± 1 cm2/min with P = 0.002, and 527 ± 273 mL with P = 0.001). ; This work was partially supported by a medical research grant from the Spanish Government (PETRI 2005/0353), from the "Programa de Promoción de la Investigación Biomédica y en Ciencias de la Salud del Ministerio de Sanidad y Consumo" of Spain (PI052498), and by the "Spanish Plan Nacional de I+D+I del Ministerio de Ciencia e Innovación" (TEC2008-01369/TEC). Finally, the publication cost were provided by the "Programa de Apoyo a la Investigación y el Desarrollo" of the Universidad Politécnica de Valencia. ; Peer reviewed

Metastases in the liver frequently grow as scattered tumor nodules which neither can be removed by surgical resection nor focally ablated. Previously, we have proposed a novel technique based on irreversible electroporation which may be able to simultaneously treat all nodules in the liver while sparing healthy tissue. The proposed technique requires increasing the electrical conductivity of healthy liver by injecting a hypersaline solution through the portal vein. Aiming to assess the capability of increasing the global conductivity of the liver by means of hypersaline fluids, here it is presented a mathematical model which estimates the NaCl distribution within the liver and the resulting conductivity change. The model fuses wellestablished compartmental pharmacokinetic models of the organ with saline injection models employed for resuscitation treatments and it considers changes in sinusoidal blood viscosity due to the hypertonicity of the solution. Here it is also described a pilot experimental study in pigs in which different volumes of NaCl 20% (from 100 to 200 ml) were injected through the portal vein at different flow rates (from 53 to 171 ml/min). The in vivo conductivity results fit those obtained by the model, both quantitatively and qualitatively, being able to predict the maximum conductivity with a 14.6% average relative error. The maximum conductivity value was 0.44 S/m which corresponds to increasing four times the mean basal conductivity (0.11 S/m). The results suggest that the presented model is well suited for predicting on liver conductivity changes during hypertonic saline injection. ; Spanish Government; contract/grant number: TEC2014-52383-C3-1-R, TEC2014-52383-C3-2-R and TEC2014-52383-C3-3-R