Comparison of In Vivo Tissue Temperature Profile and Lesion Geometry for Radiofrequency Ablation With a Saline-Irrigated Electrode Versus Temperature Control in a Canine Thigh Muscle Preparation

Circulation ◽  
1995 ◽  
Vol 91 (8) ◽  
pp. 2264-2273 ◽  
Author(s):  
Hiroshi Nakagawa ◽  
William S. Yamanashi ◽  
Jan V. Pitha ◽  
Mauricio Arruda ◽  
Xanzhung Wang ◽  
...  
Keyword(s):  
Radiofrequency Ablation ◽  
Temperature Profile ◽  
Temperature Control ◽  
Tissue Temperature ◽  
Thigh Muscle ◽  
Muscle Preparation ◽  
Irrigated Electrode

scholarly journals Comparison of In Vivo Tissue Temperature Profile and Lesion Geometry for Radiofrequency Ablation with High Power-Short Duration and Moderate Power-Moderate Duration: Effects of Thermal Latency and Contact Force on Lesion Formation

2021 ◽  
Author(s):  
Hiroshi Nakagawa ◽  
Atsushi Ikeda ◽  
Tushar Sharma ◽  
Assaf Govari ◽  
John Ashton ◽  
...  
Keyword(s):  
Temperature Profile ◽  
High Power ◽  
Lesion Size ◽  
Tissue Temperature ◽  
Thigh Muscle ◽  
Muscle Preparation ◽  
Tissue Heating ◽  
Moderate Power ◽  
Rf Applications

Background - With short radiofrequency (RF) applications, tissue temperature continues to rise after RF-termination ("thermal latency"), which may result in lesion growth after RF-termination. The purpose was to compare in-vivo tissue temperature profile (thermal latency), lesion size and the incidence of steam pop and thrombus between RF-ablation with very-high-power-very-short-RF(90W/4s), high-power-short-RF(50W/10s) and moderate-power-moderate-RF(30W/30s) in a canine thigh muscle preparation and beating heart. Methods - In the thigh muscle preparation (5dogs), a 3.5mm ablation-electrode with 66 or 56 small irrigation holes (QDOT-Micro or ThermoCoolSmartTouch-SF, respectively) was held perpendicular or parallel to the muscle at 10 or 30g contact force (CF). Total of 120RFs were delivered at 90W/4s(QDOT-catheter), 50W/10s or 30W/30s(SF-catheter). Electrode temperature, electrode-tissue-interface temperature and tissue temperatures at 3mm and 7mm-depths were measured. In 6 closed-chest dogs, total of 72RFs were delivered in the ventricle at 90W/4s, 50W/10s or 30W/30s. Results - In the thigh muscle preparation, tissue temperatures and lesion size (depth, diameter and volume) were lowest/smallest for RFs at 90W/4s, followed by 50W/10s and greatest for 30W/30s. Thermal latency (Δtemperature and duration) was greatest for RFs at 90W/4s, followed by 50W/10s and smallest for 30W/30s ( p <0.01). Effective tissue heating (area under curve≥50°C at 3mm-depth) was observed after RF-termination in 88.0±7.6% with 90W/4s, 57.7±14.6% with 50W/10s, and only 31.9±8.5% with 30W/30s ( p <0.01). In beating hearts, lesion size was also smallest with 90W/4s and greatest with 30W/30s RFs. Increasing CF significantly increased lesion depth in all three groups. There was no significant difference in the incidence of steam pop or thrombus between three groups. Conclusions - Tissue temperatures and lesion size (depth, diameter and volume) were lowest/smallest for RF-applications at 90W/4s, followed by 50W/10s and greatest for 30W/30s. The greater thermal latency for 90W/4s RF-applications suggests that a significant portion of lesion is created after RF-termination due to conductive tissue heating.

A multicouple probe for temperature gradient measurements in biological materials

1988 ◽  
Vol 65 (5) ◽  
pp. 2337-2342 ◽  
Author(s):  
M. B. Ducharme ◽  
J. Frim
Keyword(s):  
Temperature Profile ◽  
Tissue Temperature ◽  
Profile Measurement ◽  
Thermal Gradients ◽  
Polyethylene Tube ◽  
Wide Range ◽  
Gradient Measurements ◽  
The Individual ◽  
Constantan Wire

An easy-to-make, sensitive, thin, flexible, multisensor probe for in vivo tissue temperature profile measurement is described. It is essentially a multijunction thermocouple (i.e., a multicouple) of type-T composition. Enamel-insulated copper wires (38 gauge) were soldered 5 mm apart to one common uninsulated constantan wire (36 gauge) and introduced into a polyethylene tube sealed at one end. The total outside diameter of the multicouple probe is less than 1 mm, and the maximum number of junctions using the specified wire sizes is approximately 16. This design permits the instantaneous measurement of a tissue temperature profile at 5-mm intervals over a distance of approximately 8 cm. An extensive calibration for the thermal conductivity effect (k effect) along the multicouple wires by means of a limb model is presented. The results show that the temperature readings of the individual junctions are significantly affected by the k effect when a thermal gradient exists along the multicouple, as is usually the case during tissue temperature measurements. However, calibration of the multicouple for the k effect yields a measurement accuracy of +/- 0.1 degree C under a wide range of gradients. This probe can be implanted in tissues to measure thermal gradients under different physiological conditions.

Simulation of Empirical Correlations Between Temperatures and Blood Perfusion During Heating Using a Temperature-Dependent Blood Perfusion Model

2004 ◽  
Author(s):  
Cuiye Chen ◽  
Robert B. Roemer
Keyword(s):  
Blood Flow ◽  
Blood Perfusion ◽  
Step Function ◽  
Human Muscle ◽  
Tissue Temperature ◽  
Thigh Muscle ◽  
Temperature Dependent ◽  
In Vivo Experiments ◽  
Perfusion Model

This study applies a recently developed temperature-dependent blood perfusion model (TDBPM) coupled with a modified, one-dimensional Pennes bioheat transfer equation to predict the blood perfusion and temperature responses to step function microwave heating applied in the in vivo experiments performed by Sekins’ et al. [1] on human thigh muscle. The TDBPM model links the perfusion increase to the tissue temperature elevation based on physiological mechanisms underlying this temperature-blood-perfusion change phenomenon, i.e., a pharmacokinetic compartmental model. This physiology-based model avoids using ad hoc time delays between blood perfusion increases and tissue temperature elevations as done in previous efforts. It also includes a mechanism that produces the threshold temperature for blood flow increases that has been observed in vivo. In our recent study [2], the TDBPM model was used to simulate both the constant temperature water bath heating used in the in vivo experiments on rat leg muscle performed by Song et al. [3], and the step function microwave heating applied in the in vivo experiments on canine thigh muscle performed by Roemer et al. [4]. The blood perfusion rates predicted by the model are compared with those in vivo experimental data obtained in rat muscle and human muscle and good agreement was obtained. The TDBPM provides a possible explanation to the biochemical and biophysical origins of the relationships between temperature and blood flow that observed in rat muscle and human muscle. The physiology-based TDBPM is a simple, generic model of muscle blood flow responses of different animals to different heating conditions, which provides the type of fundamental information needed for the design of methods to thermally control blood flow in medical applications.

scholarly journals Perivascular vital cells in the ablation center after multibipolar radiofrequency ablation in an in vivo porcine model

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
F. G. M. Poch ◽  
C. A. Neizert ◽  
B. Geyer ◽  
O. Gemeinhardt ◽  
S. M. Niehues ◽  
...  
Keyword(s):  
Radiofrequency Ablation ◽  
Early Stage ◽  
Pringle Maneuver ◽  
Vessel Diameter ◽  
Inflow Occlusion ◽  
White Zone ◽  
Cell Vitality ◽  
Internally Cooled ◽  
Hepatic Vessels

AbstractMultibipolar radiofrequency ablation (RFA) is an advanced ablation technique for early stage hepatocellular carcinoma and liver metastases. Vessel cooling in multibipolar RFA has not been systematically investigated. The objective of this study was to evaluate the presence of perivascular vital cells within the ablation zone after multibipolar RFA. Multibipolar RFA were performed in domestic pigs in vivo. Three internally cooled bipolar RFA applicators were used simultaneously. Three experimental settings were planned: (1) inter-applicator-distance: 15 mm; (2) inter-applicator-distance: 20 mm; (3) inter-applicator-distance: 20 mm with hepatic inflow occlusion (Pringle maneuver). A vitality staining was used to analyze liver cell vitality around all vessels in the ablation center with a diameter > 0.5 mm histologically. 771 vessels were identified. No vital tissue was seen around 423 out of 429 vessels (98.6%) situated within the central white zone. Vital cells could be observed around major hepatic vessels situated adjacent to the ablation center. Vessel diameter (> 3.0 mm; p < 0.05) and low vessel-to-ablation-center distance (< 0.2 mm; p < 0.05) were identified as risk factors for incomplete ablation adjacent to hepatic vessels. The vast majority of vessels, which were localized in the clinically relevant white zone, showed no vital perivascular cells, regardless of vessel diameter and vessel type. However, there was a risk of incomplete ablation around major hepatic vessels situated directly within the ablation center. A Pringle maneuver could avoid incomplete ablations.

scholarly journals Feasibility of balloon-based endobiliary radiofrequency ablation under cholangioscopy guidance in a swine model

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tadahisa Inoue ◽  
Hiromu Kutsumi ◽  
Mayu Ibusuki ◽  
Masashi Yoneda
Keyword(s):  
Radiofrequency Ablation ◽  
Adverse Events ◽  
Swine Model ◽  
Biliary Strictures ◽  
Tissue Samples ◽  
Ablation Area ◽  
Mucosal Changes ◽  
The Mean ◽  
Preliminary Study

AbstractAlthough endobiliary radiofrequency ablation (RFA) has demonstrated considerable potential for the treatment of biliary strictures, conventional catheter RFA has several limitations. This study aimed to evaluate the feasibility of a novel cholangioscopy (CS)-guided balloon-based RFA procedure in vivo using a swine model. CS-guided balloon-RFA was performed under endoscopic retrograde cholangiography guidance at target temperatures of 60 ℃ or 70 ℃, which were maintained for 60 s. We evaluated the technical feasibility, adverse events, and histological effects associated with the procedure. Twelve sites were ablated in seven miniature pigs. The CS-guided balloon-RFA procedure was technically successful in all cases without any hindrance. Mucosal changes could be detected during RFA, and the ablation area was identified on CS. Necropsy was performed in four pigs on the same day as the procedure: the tissue samples showed coagulative necrosis, and the entire internal circumference of the bile duct was uniformly ablated. The mean lengths of the ablation area in the samples ablated at 60 °C and 70 °C were 20.64 and 22.18 mm, respectively, while the mean depths were 3.46 and 5.07 mm, respectively. The other three pigs were reared and euthanized and autopsied 35 days after the procedure. The site to be ablated had replaced the granulation tissue and fibrotic changes. No adverse events were observed in any case. CS-guided balloon-RFA appears to be a promising option for treating biliary strictures. This preliminary study could pave the way for the evaluation of this procedure in future human clinical trials.

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