Minimal vascular flows cause strong heat sink effects in hepatic radiofrequency ablation ex vivo

Lehmann, Kai S.; Poch, Franz; Rieder, Christian; Schenk, Andrea; Stroux, Andrea; Frericks, Bernd; Gemeinhardt, Ole; Holmer, Christoph; Kreis, Martin E.; Ritz, JP; Zurbuchen, Urte

doi:10.1002/jhbp.370

Cited by 27 publications

(34 citation statements)

References 33 publications

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“…Of note, RFA still exhibits some limitations in the treatment of liver cancer, and the most important limitation is the heat sink effect, in which the lower temperature is not sufficient to inactivate tumor cells and may cause incomplete ablation. [ 50 ] Lehmann et al [ 51 ] used in vitro experiments to confirm that a minimum vascular flow of 1 mL/min could cause an obvious heat sink effect during the RFA of isolated liver. A single-center retrospective study by Lin et al [ 52 ] found that the heat sink effect caused by blood vessels was an important factor of the recurrence of liver malignant tumors after RFA.…”

Section: Discussionmentioning

confidence: 99%

Radiofrequency ablation versus microwave ablation for early stage hepatocellular carcinoma

Han

Yong-sheng²,

Wang³

2020

Medicine

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Background: Several randomized control trials (RCTs) were conducted to compare microwave ablation (MWA) and radiofrequency ablation (RFA) in the treatment of hepatocellular carcinoma (HCC) over the years. The purpose of this study was to compare the efficacy of RFA and MWA for early stage HCC. Methods: Studies were systematically searched on Emabse, Ovid Medline, PubMed, and Cochrane Library until March 20, 2020. Continuous variables and dichotomous variables were compared using weighted mean difference (WMD) and odds ratio (OR), respectively. For the comparison of overall survival (OS) and disease-free survival (DFS), the hazard ratio (HR) and 95% confidence interval (CI) were extracted from univariate analysis or survival plots. Results: A total of 26 studies (5 RCTs and 21 cohorts) with 4396 patients (2393 patients in RFA and 2003 patients in MWA) were included in our study. Of these patients, 47% received treatment under general anesthesia in the MWA group and 84% in the RFA group (OR = 0.529, P < .001). The median ablation time was reduced in the MWA group (12 minutes) compared with RFA group (29 minutes) (WMD = –15.674, P < .001). In total, 17.6% patients exhibited progression during follow-up in the MWA group compared with 19.5% in the RFA group (OR = 0.877, P = .225). No statistically significant differences were observed between MWA and RFA groups in terms of OS and DFS (HR = 0.891 and 1.014, P = .222 and .852, respectively). Conclusions: MWA exhibited similar therapeutic effects as RFA in the treatment of early stage HCC. Given the shorter ablation time, MWA can be performed under local anesthesia.

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Section: Discussionmentioning

confidence: 99%

Radiofrequency ablation versus microwave ablation for early stage hepatocellular carcinoma

Han

Yong-sheng²,

Wang³

2020

Medicine

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“…The ablation effect of the metastasis near great vessels is not satisfactory. This may be due to the heat sink effect; that is, the blood vessels in the liver take away some of the heat from the thermal ablation zone, which will cause local cooling and prevent complete ablation[ 38 , 39 ]. Existing studies have suggested that ablation treatment can effectively treat CLM, especially when the metastasis is ≤ 3 cm; however, when the lesion is larger than 5 cm, it is difficult to achieve complete necrosis using ablation treatment.…”

Section: Discussionmentioning

confidence: 99%

Prognostic factors and therapeutic effects of different treatment modalities for colorectal cancer liver metastases

Wang

Wei

et al. 2020

WJGO

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BACKGROUND Colorectal cancer (CRC) is one of the most common malignant tumors in China, and the liver is the most common metastatic site in patients with advanced CRC. Hepatectomy is the gold standard treatment for colorectal liver metastases. For patients who cannot undergo radical resection of liver metastases for various reasons, ablation therapy, interventional therapy, and systemic chemotherapy can be used to improve their quality of life and prolong their survival time. AIM To explore the prognostic factors and treatments of liver metastases of CRC. METHODS A retrospective analysis was conducted on 87 patients with liver metastases from CRC treated at the Liaoning Cancer Hospital and Institute between January 2005 and March 2011. According to different treatments, the patients were divided into the following four groups: Surgical resection group (36 patients); ablation group (23 patients); intervention group (15 patients); and drug group (13 patients). The clinicopathological data and postoperative survival of the four groups were analyzed. The Kaplan-Meier method was used for survival analysis, and the Cox proportional hazards regression model was used for multivariate analysis. RESULTS The median survival time of the 87 patients was 38.747 ± 3.062 mo, and the 1- and 3-year survival rates were 87.5% and 53.1%, respectively. The Cox proportional hazards model showed that the following factors were independent factors affecting prognosis: The degree of tumor differentiation, the number of metastases, the size of metastases, and whether the metastases are close to great vessels. The results of treatment factor analysis showed that the effect of surgical treatment was better than that of drugs, intervention, or ablation alone, and the median survival time was 48.83 ± 4.36 mo. The drug group had the worst prognosis, with a median survival time of only 13.5 ± 0.7 mo ( P < 0.05). For patients with liver metastases of CRC near the great vessels, the median survival time (27.3 mo) of patients undergoing surgical resection was better than that of patients using other treatments (20.6 mo) ( P < 0.05). CONCLUSION Patients with a low degree of primary tumor differentiation, multiple liver metastases (number of tumors > 4), and maximum diameter of liver metastases > 5 cm have a poor prognosis. Among drug therapy, intervention, ablation, and surgical treatment options, surgical treatment is the first choice for liver metastases. When liver metastases are close to great vessels, surgical treatment is significantly better than drug therapy, intervention, and ablation alone.

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“…Therefore, the study was performed with a glass tube that simulated a liver vessel to achieve a standardized setup. The isolating properties of the glass tube can be neglected, as it was situated outside of the electrical field of the applicators [9], [11], [12], [26]. Energy transmission took place at the position of the glass tube by direct temperature transfer.…”

Section: Discussionmentioning

confidence: 99%

“…Stopping the peristaltic pump simulated a Pringle maneuver. The test settings, which are specified above, corresponded to parameters that were established within our research group [9], [11], [12].…”

Section: Methodsmentioning

confidence: 99%

Intermittent Pringle maneuver may be beneficial for radiofrequency ablations in situations with tumor-vessel proximity

Poch

Neizert

Gemeinhardt

et al. 2018

Innovative Surgical Sciences

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BackgroundRadiofrequency ablation (RFA) represents a treatment option for non-resectable liver malignancies. Larger ablations can be achieved with a temporary hepatic inflow occlusion (Pringle maneuver – PM). However, a PM can induce dehydration and carbonization of the target tissue. The objective of this study was to evaluate the impact of an intermittent PM on the ablation size.MethodsTwenty-five multipolar RFAs were performed in porcine livers ex vivo. A perfused glass tube was used to simulate a natural vessel. The following five test series (each n=5) were conducted: (1) continuous PM, (2–4) intermittent PM, and (5) no PM. Ablations were cut into half. Ablation area, minimal radius, and maximal radius were compared.ResultsNo change in complete ablation size could be measured between the test series (p>0.05). A small rim of native liver tissue was observed around the glass tube in the test series without PM. A significant increase of ablation area could be measured on the margin of the ablations with an intermittent PM, starting without hepatic inflow occlusion (p<0.05).ConclusionAn intermittent PM did not lead to smaller ablations compared to a continuous or no PM ex vivo. Furthermore, an intermittent PM can increase the ablation area when initial hepatic inflow is succeeded by a PM.

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Minimal vascular flows cause strong heat sink effects in hepatic radiofrequency ablation ex vivo

Cited by 27 publications

References 33 publications

Radiofrequency ablation versus microwave ablation for early stage hepatocellular carcinoma

Radiofrequency ablation versus microwave ablation for early stage hepatocellular carcinoma

Prognostic factors and therapeutic effects of different treatment modalities for colorectal cancer liver metastases

Intermittent Pringle maneuver may be beneficial for radiofrequency ablations in situations with tumor-vessel proximity

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