Radiofrequency Thermal Ablation Heat Energy Transfer in an Ex-Vivo Model

2017 ◽  
Vol 83 (12) ◽  
pp. 1373-1380 ◽  
Author(s):  
Shivani Thakur ◽  
Sandi Lavito ◽  
Elizabeth Grobner ◽  
Mark Grobner

Little work has been done to consider the temperature changes and energy transfer that occur in the tissue outside the vein with ultrasound-guided vein ablation therapy. In this experiment, a ex-vivo model of the human calf was used to analyze heat transfer and energy degradation in tissue surrounding the vein during endovascular radiofrequency ablation (RFA). A clinical vein ablation protocol was used to determine the tissue temperature distribution in 10 per cent agar gel. Heat energy from the radiofrequency catheter was measured for 140 seconds at fixed points by four thermometer probes placed equidistant radially at 0.0025, 0.005, and 0.01 m away from the RFA catheter. The temperature rose 1.5°C at 0.0025 m, 0.6°C at 0.005 m, and 0.0°C at 0.01 m from the RFA catheter. There was a clinically insignificant heat transfer at the distances evaluated, 1.4 ± 0.2 J/s at 0.0025 m, 0.7 ± 0.3 J/s at 0.0050 m, and 0.3 ± 0.0 J/s at 0.01 m. Heat degradation occurred rapidly: 4.5 ± 0.5 J (at 0.0025 m), 4.0 ± 1.6 J (at 0.0050 m), and 3.9 ± 3.6 J (at 0.01 m). Tumescent anesthesia injected one centimeter around the vein would act as a heat sink to absorb the energy transferred outside the vein to minimize tissue and nerve damage and will help phlebologists strategize options for minimizing damage.

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Michael G Paulus ◽  
Kathrin Renner ◽  
Steffen Pabel ◽  
Gabriela Pietrzyk ◽  
Andreas Luchner ◽  
...  

Introduction: Clinical significance of tachycardiomyopathy (TCM) increased with trials on catheter ablation therapy. Myocardial biopsies from patients show disturbed mitochondrial architecture. Hypothesis: TCM involves mitochondrial dysfunction. Methods: First, TCM was investigated in an animal model: pacemaker implantation in 7 rabbits was followed by tachypacing for 30 days (TCM), 7 animals served as sham-operated controls (SHAM). Second, results of the animal study were evaluated for their translational perspective for human disease using a novel model of induced pluripotent stem cell-derived cardiomyocytes (iPS-CM), derived from 4 healthy donors. IPS-CM were paced with 120 bpm (TACH) or 60 bpm (CTRL) for 7 days in vitro. Targeted transcriptomics, high-resolution respirometry and flow cytometry (MitoSOX Red) were performed. To account for variations between cell differentiations, experiments on iPS-CM were carried out in a paired design. Results: TCM showed LV dilatation and dysfunction (ΔLVEDD +5.3±0.2mm; ΔFS -19±8%; TCM-SHAM; p<0.001). Histological findings resembled human disease entailing cardiomyocyte hypertrophy (CSA 519±32μm 2 vs. 413±21μm 2 , p<0.01) without fibrosis (hydroxyproline content, p=0.52). Mitochondrial transcriptome of TCM was characterized by downregulation of 10 antioxidative enzymes (e.g. GPX3, fold change (FC) 0.4; TCM/SHAM; p<0.05) as well as mitochondrial carriers, including ADP/ATP- and NADH-shuttling (SLC25A4, FC 0.7; SLC25A12, FC 0.8; p<0.01). As transcriptomics implied impaired substrate import, respirometry was performed in whole tissue. In support of our findings on the transcriptome level, mitochondrial oxidative phosphorylation capacity decreased in TCM (133±13 vs. 170±16 pmol·O 2 ·s -1 ·mg -1 ·tissue, p<0.05). Similarly, oxidative phosphorylation was reduced in iPS-CM (995±738 vs. 1838±901 pmolO 2 ·s -1 ·IU -1 citrate synthase activity, TACH vs. CTRL, p<0.01). Concurrently, tachypacing increased mitochondrial superoxide emission in iPS-CM (MFI 491±206 vs. 301±119, p<0.05). Conclusions: Persistent tachycardia alters two mitochondrial key functions in an animal and a novel human ex vivo model: oxidative phosphorylation capacity is reduced, while superoxide emission increases.


Author(s):  
C. Bachmann ◽  
I. Sautkin ◽  
G. Nadiradze ◽  
R. Archid ◽  
F. J. Weinreich ◽  
...  

Abstract Background Optimized drug delivery systems are needed for intraperitoneal chemotherapy. The aim of this study was to develop a technology for applying pressurized intraperitoneal aerosol chemotherapy (PIPAC) under hyperthermic conditions (hPIPAC). Methods This is an ex-vivo study in an inverted bovine urinary bladder (IBUB). Hyperthermia was established using a modified industry-standard device (Humigard). Two entry and one exit ports were placed. Warm-humid CO2 was insufflated in the IBUB placed in a normothermic bath to simulate body thermal inertia. The temperature of the aerosol, tissue, and water bath was measured in real-time. Results Therapeutic hyperthermia (target tissue temperature 41–43 °C) could be established and maintained over 30 min. In the first phase (insufflation phase), tissue hyperthermia was created by insufflating continuously warm-humid CO2. In the second phase (aerosolization phase), chemotherapeutic drugs were heated up and aerosolized into the IBUB. In a third phase (application phase), hyperthermia was maintained within the therapeutic range using an endoscopic infrared heating device. In a fourth phase, the toxic aerosol was discarded using a closed aerosol waste system (CAWS). Discussion We introduce a simple and effective technology for hPIPAC. hPIPAC is feasible in an ex-vivo model by using a combination of industry-standard medical devices after modification. Potential pharmacological and biological advantages of hPIPAC over PIPAC should now be evaluated.


2020 ◽  
Vol 50 (4) ◽  
pp. 137-141
Author(s):  
Josef Skopalík ◽  
Jiří Sekora ◽  
Martin Pešl ◽  
Markéta Bébarová ◽  
Olga Švecová ◽  
...  

Biological experiments involving isolated organs and tissues demand precise temperature monitoring and regulation. An automatic temperature control system was proposed and optimised on real isolated swine hearts and the prototype is described in this work. The traditional Langendorff apparatus consists of a heart holder, a reservoir of perfusion solution flowing to aortic cannula and a heating bath allowing passive heat transfer to the reservoir of perfusion solution. The commercial infrared camera FLIR T62101 was added to this basic set-up and used for very precise monitoring of the temperature kinetic of the organ and connected with an electronic feedback loop, which allowed real-time and precise regulation of heat transfer from the heating bath to the perfusion solution and in turn indirectly to the heart tissue. This provides real time control and active regulation of the myocardial tissue temperature. The infrared camera was tested in several modes and several variants of detection were optimised for ideal measurement of the region of interest of the ex vivo organ. The kinetics of the temperature changes and temperature stability of the tissue were recorded and calibrated by external electronic thermometers (type Pt100, inserted in tissue). The time lapse from the hang-up of the hypo termed organ (30 °C) until optimal warming (37 °C) was less than eight minutes in the final instrument prototype. The final stability of the 37 °C tissue temperature was approved; the temperature fluctuation of left ventricle tissue was characterised as 36.8 ± 0.5 °C. This upgraded traditional instrument could be used in specific preclinical and clinical transplantation and analytical projects in future.


Author(s):  
M. Erol Ulucakli

Heat transfer in radiofrequency ablation therapy of liver tumors is discussed. Temporal and spatial temperature changes around a single needle and multi-prong ablation probes in monopolar and bipolar configurations based on a two-dimensional finite elements method are presented. The temperature changes and related heat transfer in the tissue model help to visualize the shape and size of the ablated region. The visualization of the tissue temperatures and their progression could be useful in clinical applications of ablation therapy. Finite-element based numerical simulation, while providing useful visualizations of the temperature changes in and around the tumor, underestimates the lesion size. The perfusion in the tissue and the possible presence of large blood vessels in or near the ablated domain, and the temperature dependency of the thermal and electrical properties of the tissue are significant complicating factors in modeling and clinical applications.


2008 ◽  
Vol 19 (6) ◽  
pp. 629-633 ◽  
Author(s):  
Osnat Feuerstein ◽  
Kobi Zeichner ◽  
Chen Imbari ◽  
Zeev Ormianer ◽  
Nachum Samet ◽  
...  

2007 ◽  
Vol 177 (4S) ◽  
pp. 614-614 ◽  
Author(s):  
Gunnar Wendt-Nordahl ◽  
Stefanie Huckele ◽  
Patrick Honeck ◽  
Peter Aiken ◽  
Thomas Knoll ◽  
...  

2017 ◽  
Author(s):  
J Houriet ◽  
YE Arnold ◽  
C Petit ◽  
YN Kalia ◽  
JL Wolfender

1995 ◽  
Vol 73 (02) ◽  
pp. 219-222 ◽  
Author(s):  
Manuel Monreal ◽  
Luis Monreal ◽  
Rafael Ruiz de Gopegui ◽  
Yvonne Espada ◽  
Ana Maria Angles ◽  
...  

SummaryThe APTT has been considered the most suitable candidate to monitor the anticoagulant activity of hirudin. However, its use is hampered by problems of standardization, which make the results heavily dependent on the responsiveness of the reagent used. Our aim was to investigate if this different responsiveness of different reagents when added in vitro is to be confirmed in an ex vivo study.Two different doses of r-hirudin (CGP 39393), 0.3 mg/kg and 1 mg/kg, were administered subcutaneously to 20 New Zealand male rabbits, and the differences in prolongation of APTT 2 and 12 h later were compared, using 8 widely used commercial reagents. All groups exhibited a significant prolongation of APTT 2 h after sc administration of hirudin, both at low and high doses. But this prolongation persisted 12 h later only when the PTTa reagent (Boehringer Mannheim) was used. In general, hirudin prolonged the APTT most with the silica- based reagents.In a further study, we compared the same APTT reagents in an in vitro study in which normal pooled plasma was mixed with increasing amount of hirudin. We failed to confirm a higher sensitivity for silica- containing reagents. Thus, we conclude that subcutaneous administration of hirudin prolongs the APTT most with the silica-based reagents, but this effect is exclusive for the ex vivo model.


2019 ◽  
Author(s):  
RF Knoop ◽  
E Wedi ◽  
V Ellenrieder ◽  
A Neesse ◽  
S Kunsch
Keyword(s):  
Ex Vivo ◽  

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