Kai S Lehmann1, Franz G M Poch1, Christian Rieder2, Andrea Schenk2, Andrea Stroux3, Bernd B Frericks4, Ole Gemeinhardt1, Christoph Holmer1, Martin E Kreis1, Jörg P Ritz5, Urte Zurbuchen1. 1. Department of General and Vascular Surgery, Charité - Universitätsmedizin Berlin, Berlin, Germany. 2. Fraunhofer Institute for Medical Image Computing MEVIS, Bremen, Germany. 3. Institute for Biometry and Clinical Epidemiology, Charité - Universitätsmedizin Berlin, Berlin, Germany. 4. Department of Diagnostic and Interventional Radiology, DRK Kliniken Berlin Westend, Berlin, Germany. 5. Department of General and Visceral Surgery, HELIOS Kliniken Schwerin, Schwerin, Germany.
Abstract
BACKGROUND: The present paper aims to assess the lower threshold of vascular flow rate on the heat sink effect in bipolar radiofrequency ablation (RFA) ex vivo. METHODS: Glass tubes (vessels) of 3.4 mm inner diameter were introduced in parallel to bipolar RFA applicators into porcine liver ex vivo. Vessels were perfused with flow rates of 0 to 1,500 ml/min. RFA (30 W power, 15 kJ energy input) was carried out at room temperature and 37°C. Heat sink effects were assessed in RFA cross sections by the decrease in ablation radius, area and by a high-resolution sector planimetry. RESULTS: Flow rates of 1 ml/min already caused a significant cooling effect (P ≤ 0.001). The heat sink effect reached a maximum at 10 ml/min (18.4 mm/s) and remained stable for flow rates up to 1,500 ml/min. CONCLUSIONS: Minimal vascular flows of ≥1 ml/min cause a significant heat sink effect in hepatic RFA ex vivo. A lower limit for volumetric flow rate was not found. The maximum of the heat sink effect was reached at a flow rate of 10 ml/min and remained stable for flow rates up to 1,500 ml/min. Hepatic inflow occlusion should be considered in RFA close to hepatic vessels.
BACKGROUND: The present paper aims to assess the lower threshold of vascular flow rate on the heat sink effect in bipolar radiofrequency ablation (RFA) ex vivo. METHODS: Glass tubes (vessels) of 3.4 mm inner diameter were introduced in parallel to bipolar RFA applicators into porcine liver ex vivo. Vessels were perfused with flow rates of 0 to 1,500 ml/min. RFA (30 W power, 15 kJ energy input) was carried out at room temperature and 37°C. Heat sink effects were assessed in RFA cross sections by the decrease in ablation radius, area and by a high-resolution sector planimetry. RESULTS: Flow rates of 1 ml/min already caused a significant cooling effect (P ≤ 0.001). The heat sink effect reached a maximum at 10 ml/min (18.4 mm/s) and remained stable for flow rates up to 1,500 ml/min. CONCLUSIONS: Minimal vascular flows of ≥1 ml/min cause a significant heat sink effect in hepatic RFA ex vivo. A lower limit for volumetric flow rate was not found. The maximum of the heat sink effect was reached at a flow rate of 10 ml/min and remained stable for flow rates up to 1,500 ml/min. Hepatic inflow occlusion should be considered in RFA close to hepatic vessels.
Authors: Franz G M Poch; Christina A Neizert; Ole Gemeinhardt; Beatrice Geyer; Katharina Eminger; Christian Rieder; Stefan M Niehues; Janis Vahldiek; Stefan F Thieme; Kai S Lehmann Journal: Innov Surg Sci Date: 2018-05-11
Authors: C A Neizert; H N C Do; M Zibell; C Rieder; D Sinden; S M Niehues; J L Vahldiek; K S Lehmann; F G M Poch Journal: Sci Rep Date: 2022-10-12 Impact factor: 4.996
Authors: F G M Poch; C A Neizert; B Geyer; O Gemeinhardt; S M Niehues; J L Vahldiek; K K Bressem; K S Lehmann Journal: Sci Rep Date: 2021-07-06 Impact factor: 4.379