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  • 1
    Language: English
    In: The Journal of Urology, 2006, Vol.175(3), pp.1122-1126
    Description: We investigated a newly developed bipolar and multipolar RF ablation system with an internally cooled electrode and resistance controlled power output in a standardized model of perfused ex vivo kidney tissue. RF energy was applied at different power levels (20, 30 and 60 W) for 1, 3, 5 and 9 minutes. Each treatment parameter was repeated 5 times. For the 20/30 W levels a bipolar electrode with an active conducting part of 20/30 mm was selected. At 60 W 2 bipolar electrodes with an active conducting part (30 mm each) were connected. Lesion volumes and shapes were calculated by measuring the maximum vertical, long axis and short axis diameters of the macroscopic lesion. Lesion volume increased significantly with the treatment time and generator power applied (p 〈0.0001). Lesion size in multipolar ablated zones was larger than that in bipolar ablated zones. A reliable dose-effect relationship existed between the generator power/applied treatment time and ablated tissue lesion size. All lesions were elliptical. Bipolar and multipolar RF ablation with an internally cooled electrode and tissue resistance control represent an interesting advance in RF technology. The development of lesion size and volume is predictable, while a uniform lesion shape can be achieved in perfused ex vivo kidney tissue. Further in vivo trials are required to test whether complete and reliable tumor tissue ablation is possible with this system.
    Keywords: Kidney ; Surgical Procedures ; Minimally Invasive ; Carcinoma ; Renal Cell ; Catheter Ablation ; Swine ; Medicine
    ISSN: 0022-5347
    E-ISSN: 1527-3792
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  • 2
    In: BJU International, April 2006, Vol.97(4), pp.822-828
    Description: To purchase or authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1464-410X.2006.06038.x Byline: AXEL HACKER, STEFAN VALLO, CHRISTEL WEISS (*), THOMAS STEIN ([dagger]), PETER ALKEN, THOMAS KNOLL, MAURICE STEPHAN MICHEL Keywords: surgical procedures; minimally invasive; carcinoma; electrodes; radiofrequency ablation Abstract: OBJECTIVE To investigate the technical characteristics of a newly developed device for bipolar and multipolar radiofrequency ablation (RFA) of kidney tissue with a resistance-controlled power output. MATERIALS AND METHODS The standardized model of the isolated perfused ex vivo porcine kidney was used. Two different applicators (20 and 30 mm active length) were selected for bipolar RFA, and one pair of applicators (2 x 30 mm active length) for multipolar RFA. RF energy was applied at different power levels (20, 30, 60 W) depending on the total active length of the electrodes. Treatment times were 1, 3, 5 and 9 min. The ablation cycles were recorded in continuous digital real-time and displayed on a monitor showing pre-set power, actual applied power, applied energy, tissue resistance, and impedance. Lesion sizes were measured macroscopically. A coagulation coefficient (coagulated tissue volume per applied energy unit) was calculated. RESULTS There was a dosage-effect relationship between the generator power/treatment time and the sizes of the lesions. With increasing treatment time, less tissue volume was coagulated per unit of applied energy. The actual applied energy was lower than that calculated theoretically. The resistance and impedance values for the 30-W applicator were lower than those of the 20-W applicator. CONCLUSIONS The technical features of this RFA device, with internally cooled bipolar and multipolar applicators and a resistance-controlled power output, represents an innovative improvement in RF technology. In vivo studies are needed to confirm the expected advantages and the suitability of this device for complete and reliable ablation of renal tumours. Author Affiliation: (*)Department of Biomathematics, University Hospital Mannheim, Ruprecht-Karls University of Heidelberg, and ([dagger])Celon AG Medical Instruments, Teltow, Germany Article History: Accepted for publication 31 October 2005 Article note: Axel Hacker, Department of Urology, University Hospital Mannheim, Theodor-Kutzer-Ufer 1-3 68135 Mannheim, Germany. e-mail: axel.haecker@chir.ma.uni-heidelberg.de
    Keywords: Surgical Procedures ; Minimally Invasive ; Carcinoma ; Electrodes ; Radiofrequency Ablation
    ISSN: 1464-4096
    E-ISSN: 1464-410X
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