Radiofrequency Ablation Protocol Research Articles

Posterior wall isolation in patients with persistent atrial fibrillation: a single center comparative study between ablation index and very high power short duration radiofrequency ablation protocol

Abstract Background Circumferential pulmonary veins ablation (CPVA) with posterior wall isolation (PWI) using radiofrequency catheter ablation (RFCA) is gaining increasing interest in terms of safety and efficacy. Purpose To compare procedural data and efficacy between two radiofrequency ablation protocols for the treatment of persistent atrial fibrillation (PersAF): very high power-short duration (vHPSD) ablation using a novel temperature-controlled ablation catheter and Ablation Index (AI) guided RFCA using traditional contact-force catheter. Methods This single center prospective study enrolled 75 consecutive patients (Group 1) with symptomatic PersAF undergoing RFCA using a novel contact-force catheter optimized for temperature-controlled ablation with microelectrodes and 6 thermocouples for real-time temperature monitoring during ablation. The vHPSD algorithm modulates power to maintain target temperature during these lesions (90 Watts, 4 s) in the posterior wall. RF delivery in anterior regions was performed in a temperature guided setting (1-45W, 45°C) to achieve a 500-550 AI. These patients were compared to 75 propensity matched patients (Group 2) undergoing PersAF ablation with traditional AI-guided ablation. Procedural data were compared between the two groups (Table 1). Procedural outcome was considered as loop recorder documented atrial arrhythmias recurrences and compared between the two groups. Results Seventy-five patients (69% male, 63.1±11.2 years old) underwent ablation with vHPSD protocol (Group 1). CPVA and PWI was achieved in all patients with total procedure and fluoroscopy times of 67.5±28.8 min and 4.5±2.8 min, respectively. After 12-month median follow-up, 57/75 patients (76%) were free from AF. Seventy-five propensity matched patients (69% male, 60.7±9.9 years old) have undergone ablation with standard contact-force catheter. CPVA and PWI was achieved in all patients with total procedure and fluoroscopy times of 81.99±20.5 min and 5.7±2.1 min, respectively. After 12-month median follow-up, 55/75 patients (73%) were free from AF. Procedural and fluoroscopy times were significantly lower in in Group 1 than in Group 2 (Table 1). AF recurrencies were comparable between the two groups as assessed with survival analysis (Figure 1, log-rank 0.509). There were no deaths or other severe periprocedural complications. Conclusions PWI on top of CPVA is effective in limiting arrhythmic recurrences following RFCA of PersAF. Compared to standard AI guided ablation, vHPSD protocol significantly reduces procedural time and fluoroscopy exposure. Clinical outcomes between the two protocols are similar.Figure 1

Shoulder terminal sensory articular nerve radiofrequency ablation for nonsurgical refractory shoulder pain due to rotator cuff pathology and osteoarthritis: a technical note.

Given the high prevalence of chronic shoulder pain and encouraging early results of terminal sensory articular branch radiofrequency ablation to treat shoulder pain, research is warranted to refine the procedural technique on the basis of updated neuroanatomic knowledge with the goal of further improving patient outcomes. We describe an updated radiofrequency ablation protocol that accounts for varied locations of the terminal sensory articular branches of the suprascapular, axillary, subscapular, and lateral pectoral nerves within individual patients. Technical note. Cadaveric studies delineating the sensory innervation of the shoulder joint were reviewed, and a more comprehensive radiofrequency ablation protocol is proposed relative to historical descriptions. The proposed radiofrequency ablation protocol, which is based on neuroanatomic dissections of the shoulder joint, will provide a safe means of more complete sensory denervation and potentially improve clinical outcomes compared with historical descriptions, the efficacy of the new protocol must be confirmed in prospective studies.

Treatment of Cystic-Solid Thyroid Nodules with Ultrasound-Guided Radiofrequency Ablation and Enhancement of Thyroid Function.

To investigate the efficacy of ultrasound-guided radiofrequency ablation and its effect on thyroid function in patients with cystic-solid thyroid nodules. We enrolled 90 patients with cystic-solid thyroid nodules and randomly assigned to either a control group (n = 37) or an observation group (n = 53). Patients in the observation group underwent ultrasound-guided radiofrequency ablation, while those in the control group were treated with ultrasound-guided lauromacrogol. Thyroid function was monitored, and complications were recorded for both groups, while nodule reduction rates were compared across a range of volumes and time periods. One month after surgery, the observation group had a larger volume of nodules than the control group, while at 12 months, the volume of nodules in the observation group was smaller. (P < 0.05). Thyroid-stimulating hormone (TSH), free thyroxine 4 (FT4), and free triiodothyronine (FT3) levels were all within normal ranges after treatment in both groups and showed no significant differences from pre-treatment levels. (P > 0.05). There was no statistically significant difference between the total incidence of adverse reactions in the control group (8.11%) and the observation group (5.66%) (P > 0.05). With a low incidence of postoperative adverse reactions, the ultrasound-guided radiofrequency ablation protocol in the clinical treatment of patients with cystic-solid thyroid nodules can effectively reduce the volume of solid thyroid nodules without affecting the thyroid function of patients and can achieve more ideal treatment effectiveness, and is deserving of promotion.

Radiofrequency ablation as a method of choice for the treatment of lower extremity varicose veins disease

The aim of the work is to improve the radiofrequency ablation (RFA) protocol in order to minimize disease recurrence and to improve the life quality of patients with lower extremity varicose veins disease (LEVVD).&#x0D; Materials and methods. An open-label, prospective study of the effectiveness of a modified RFA protocol for the treatment of 210 consecutive patients with clinical grade C2-C6 of LEVVD was conducted. The effectiveness and safety of the procedure were evaluated by the anatomical success of vein obliteration, the dynamics of the severity of venous pathology according to the VCSS scale, quality of life indicators determined using the AVVQ-UA questionnaire, and development of postoperative complications.&#x0D; Results. Sonographic control was conducted in the first 48 hours, 7 days and 1 month after the RFA procedure and recorded 100 % occlusion of the great saphenous vein, obtaining the effect of “radiofrequency crossectomy” in the jugular area. After 6 months and 1 year of follow-up, 208 (99.1 %) patients experienced vein occlusion and 2 (0.9 %) patients had partial vein occlusion within 1 cm of the sapheno-femoral junction without pathological reflux. After 2 years the partial occlusion was diagnosed in 4 (1.9 %) patients.&#x0D; During the first 2 weeks after treatment, 64 (30.5 %) patients reported complications, which didn’t require treatment. However, in 2 (0.9 %) cases asymptomatic distal DVT and in 1 (0.5 %) EHIT II were diagnosed. Anticoagulant therapy was prescribed. Regression of clinical symptoms with a statistically significant difference in the VCSS score (p &lt; 0.001) was observed 6 months after RFA. The application of the proposed RFA protocol made it possible to statistically significantly improve the quality of life indicators 1 month after treatment by 3.36 ± 0.81 (р &lt; 0.001) with further positive dynamics.&#x0D; Conclusions. The application of the proposed RFA protocol in patients with LEVVD has a good safety profile, allows to minimize disease recurrences, performing the effect of “radiofrequency crossectomy”, and has a positive effect on the regression of clinical symptoms and quality of life indicators.

Radiofrequency ablation for liver tumors abutting complex blood vessel structures: treatment protocol optimization using response surface method and computer modeling

Objective To achieve a result of a large tumor ablation volume with minimal thermal damage to the surrounding blood vessels by designing a few clinically-adjustable operating parameters in radiofrequency ablation (RFA) for liver tumors abutting complex vascular structures. Methods Response surface method (RSM) was employed to correlate the ablated tumor volume () and thermal damage to blood vessels () based on RFA operating parameters: ablation time, electrode position, and insertion angle. A coupled electric-thermal-fluid RFA computer model was created as the testbed for RSM to simulate RFA process. Then, an optimal RFA protocol for the two conflicting goals, namely (1) large tumor ablation and (2) small thermal damage to the surrounding blood vessels, has been achieved under a specific ablation environment. Results Linear regression analysis confirmed that the RFA protocol significantly affected and (the adjusted coefficient of determination = 93.61% and 95.03%, respectively). For a proposed liver tumor scenario (liver tumor with a dimension of 432.9 cm3 abutting a complex vascular structure), an optimized RFA protocol was found based on the regression results in RSM. Compared with a reference RFA protocol, in which the electrode was centered in the tumor with a 12-min ablation time, the optimized RFA protocol has increased from 98.1% to 99.6% and decreased from 4.1% to 0.4%, achieving nearly the complete ablation of proposed liver tumor and ignorable thermal damages to vessels. Conclusion This work showed that it is possible to design a few clinically-adjustable operating parameters of RFA for achieving a large tumor ablation volume while minimizing thermal damage to the surrounding blood vessels.

A Pilot Study of an Expanded Genicular Nerve Radiofrequency Ablation Protocol for the Treatment of Chronic Knee Pain.

A Pilot Study of an Expanded Genicular Nerve Radiofrequency Ablation Protocol for the Treatment of Chronic Knee Pain.

Shorter interlesion distance is associated with a longer procedure time but not with poorer acute results of pulmonary vein isolation: results from a prospective ablation index registry

Abstract Funding Acknowledgements Type of funding sources: Other. Main funding source(s): This work was supported by the Ministry of Science and Higher Education grant (Russian Federation President Grant) #MD-2314.2020.7. Background/Introduction. Radiofrequency ablation (RFA) is the mainstay of invasive management of atrial fibrillation (AF). Amongst a variety of performance indicators, interlesion distance (ILD) has a potential to become a guiding one. Uptodate clinical AF RFA protocols suggest that ILD has to be less than 6 mm, however the research is still lacking in regard to its actual targeted value. Purpose. The aim of the research is to study a relationship between ILD and first-pass isolation (FPI) in ablation-index guided AF ablation procedures. Methods. This was a prospective observational multicenter study. Data were derived from the web-based system. Pulmonary veins (PV) isolation procedures were performed according to the local practice, and RFA settings depended on operators’ preferences. A total of 446 patients were enrolled, 407 of them underwent first-time AF ablation, data on ILD available in 322 subjects (177 (55%) males, mean age 62 ± 9 years old, 259 (80%) with paroxysmal AF). A mean ILD was calculated manually in each case as a sum of all ILDs divided by number of ablation tag points. FPI was considered in cases when no additional applications were required for bidirectional PV block following creation of a one circle around ipsilateral PVs and after a 20-min waiting period. Patients were divided into two groups according to ILD (Group 1 ILD≤ 4 mm, 163 patients and Group 2 ILD &amp;gt; 4m, 159 patients) post-procedurally. Results. The mean procedure time was 102 ± 52 min, the median fluoro time was 9 min [IQR 6; 15]. The following VisiTag parameters were used: the median target ablation index 400 [IQR 400; 500] on the left atrial anterior wall and 380 [IQR 380; 400] on the posterior segments, the median minimal contact force 3g [IQR 3; 4], median minimal time per a point - 4 sec [IQR 3; 15], mean catheter stability 3 mm (ranged between 2.5 and 3 mm). In 261 (81%) cases operators used 3 mm ablation tag size, and in 19% - 2 mm. The mean ILD was 4,1 ± 1,0 mm (3,2 ± 0,5 mm in Group 1 vs 4,6 ± 0,5 mm Group 2). FPI was achieved in 189 (59%) cases. In the "ILD ≤ 4 mm" group FPI was achieved in 93 (49,2%) cases and there were 96 (50,8%) cases of durable FPI in the "ILD &amp;gt;4 mm" group (χ2 = 2,4, p = 0,124). The mean procedure time was 111 ± 46 min and 100 ± 35 min in Group 1 and 2 (p = 0,01), respectively. The mean fluoro time was 13 ± 4 min and 11 ± 4 min in Group 1 and 2 (p = 0,08), respectively Conclusion(s). The results of our multicenter study suggest that shortening of the distance ≤4 mm has no effect on the achievement of first-pass PV isolation, but required more procedure and relatively more X-ray exposure time.

Lesion size and adjacent tissue damage assessment with high power and short duration radiofrequency ablation: comparison to conventional radiofrequency ablation power setting.

There is increased interest in creating high-power short duration (HPSD) ablation lesions in the field of atrial fibrillation (AF) radiofrequency ablation (RFA). We evaluated the lesion characteristics and collateral damage using two separate RFA protocols setting (HPSD: 50W and 7s vs control: 25W and 30s) in vitro model. Sixteen freshly killed porcine hearts were obtained, and the atrium and ventricle slabs were harvested for ablation. The each slabs were placed in a tissue bath with circulating 0.9% NaCl at maintained temperature 37°C. RFA was performed with 4mm tip irrigated force sensing catheter. All lesions were ablated under recording the electrical parameters using with Ensite Navx system (St. Jude Medical, St. Paul, Minnesota). After RFA, lesion characteristics were assessed for each lesion. Thirty-five lesions were made for each ablation protocol (total 70 lesions for analysis). Ablation parameters were similar between two groups (HPSD vs control; impedance drop (Ω): 34.2 ± 13.1 vs 36.1 ± 8.65 P = 0.49, contact force (g): 13.9 ± 4.37 vs 14.6 ± 5.09, P = 0.51, lesion size index: 4.8 ± 0.52 vs 4.73 ± 0.59, P = 0.62). Although the lesion volume was similar, the HPSD ablation creates wider but more shallower lesions compared to control group (HPSD vs control; lesion volume: 29.6 ± 18.1mm3 vs 35.5 ± 17.1mm3 P = 0.16, lesion diameter: 4.98 ± 0.91mm vs 4.45 ± 0.74mm P = 0.0095, lesion depth: 2.2 ± 0.76mm vs 2.8 ± 1.56mm P = 0.046). Of these, 38 lesions were assessed for adjacent tissue damage and adjacent tissue damages were more frequent seen in control group (HPSD vs control; 1/19 (5.26%) vs 6/19 (31.5%), P = 0.036). Effective lesions were made with HPSD, thereby reducing RFA procedure time. Although the lesion volume was similar between two groups, collateral damage was less seen in HPSD group attributed by lesion characteristics.

Standard versus simplified radiofrequency ablation protocol for Barrett’s esophagus: comparative analysis of the whole treatment pathway

Background and study aims The standard radiofrequency ablation (RFA) protocol for Barrett’s esophagus (BE) encompasses an intermediary cleaning phase between two ablation sessions. A simplified protocol omitting the cleaning phase is less labor-intensive but equally effective in studies based on single ablation procedures. The aim of this study was to compare efficacy and safety of the standard and simplified RFA protocols for the whole treatment pathway for BE, including both circumferential and focal devices. Patients and methods We performed a retrospective analysis of prospectively collected data on patients receiving RFA between January 2007 and August 2017 at two institutions. Outcomes assessed were: 1) complete remission of dysplasia (CR-D) and intestinal metaplasia (CR-IM) at 18 months; and 2) rate of esophageal strictures. Results One hundred forty-five patients were included of whom 73 patients received the standard and 72 patients received the simplified protocol. CR-D was achieved in 94.5 % and 95.8 % of patients receiving the standard and simplified protocol, respectively ( P = 0.71). CR-IM was achieved in 84.9 % and 77.8 % of patients treated with the standard and simplified protocol, respectively ( P = 0.27). Strictures were significantly more common among patients who received the simplified protocol (12.5 %) compared to the standard protocol (1.4 %; P = 0.008). The median number of esophageal dilations was one. Conclusion The simplified RFA protocol is as effective as the standard protocol in eradicating BE but carries a higher risk of strictures. This needs to be taken into account, particularly in patients with higher pretreatment risk of strictures, such as those with esophageal narrowing from previous endoscopic mucosal resection (EMR).

Evaluation of suprascapular nerve radiofrequency ablation protocols: 3D cadaveric needle placement study

Background and objectivesImage-guided intervention of the suprascapular nerve is a reported treatment to manage chronic shoulder joint pain. The suprascapular nerve is conventionally targeted at the suprascapular notch; however, targeting...

A Novel Technical Protocol for Improved Capture of the Genicular Nerves by Radiofrequency Ablation.

Fluoroscopically guided cooled genicular nerve radiofrequency ablation (RFA) is an increasingly performed procedure for chronic, refractory knee pain due to osteoarthritis. Traditionally, partial sensory denervation has been accomplished through ablation of the superomedial, superolateral, and inferomedial genicular nerves. However, recent cadaveric studies have demonstrated additional sensory nerves and significant anatomic variation that impact current protocols. We describe an updated cooled genicular nerve radiofrequency ablation protocol that accounts for varied nerve location of the superomedial, superolateral, and inferomedial genicular nerves, as well as capture of the terminal articular branches of the nerves to the vastus intermedius, vastus lateralis, and vastus medialis. Furthermore, we describe an adjusted technique for inferomedial genicular nerve capture that mitigates the risk of pes anserine tendon injury. Technical report and brief literature review. Cadaveric studies relating to the sensory innervation of the anterior knee joint were reviewed, and a more accurate and comprehensive cooled genicular nerve radiofrequency ablation (CRFA) protocol is proposed. Based on recent, rigorous anatomic dissections of the knee, the proposed genicular nerve CRFA protocol will provide more complete sensory denervation and potentially improve clinical outcomes. Prospective studies will be needed to confirm the hypothesis that this protocol will result in improved effectiveness and safety of genicular nerve RFA.

Design of a Novel Electrode of Radiofrequency Ablation for Large Tumors: In Vitro Validation and Evaluation.

In a prior study, we proposed a novel monopolar expandable electrode (MEE) for use in radiofrequency ablation (RFA). The purpose of our work was to now validate and evaluate this electrode using on in vitro experimental model and computer simulation. Two commercially available RF electrodes (conventional electrode (CE) and umbrella electrode (UE)) were used to compare the ablation results with the novel MEE using an in vitro egg white model and in vivo liver tumor model to verify the efficacy of MEE in the large tumor ablation, respectively. The sharp increase in impedance during RFA procedures was taken as the termination of RFA protocols. In the in vitro egg white experiment, the ablation volume of MEE, CE, and UE was 75.3 ± 1.6 cm3, 2.7 ± 0.4 cm3, and 12.4±1.8 cm3 (P < 0.001), respectively. Correspondingly, the sphericity was 88.1±0.9%, 12.9±1.3%, and 62.0 ± 3.0% (P < 0.001), respectively. A similar result was obtained in the in vitro egg white computer simulation. In the liver tumor computer simulation, the volume and sphericity of ablation zone generated by MEE, CE, and UE were 36.6 cm3 and 93.6%, 3.82 cm3 and 16.9%, and 13.5 cm3 and 56.7%, respectively. In summary, MEE has the potential to achieve complete ablation in the treatment of large tumors (>3 cm in diameter) compared to CE and UE due to the larger electrode-tissue interface and more round shape of hooks.

Radiofrequency-induced thermotherapy (RFiTT) in a porcine liver model and ex vivo great saphenous vein

Aims: To investigate the thermal spread achieved in porcine liver when using an optimised radiofrequency ablation protocol and correlate findings with the effects seen in ex vivo great saphenous vein (GSV), in order to justify clinical use with the new treatment protocol.Material and methods: Porcine liver and GSV sections were treated with radiofrequency-induced thermotherapy (RFiTT) using the following settings: 20 W at 1 s/cm (linear endovenous energy density; LEED 20 J/cm), 18 W at 1 s/cm (LEED 18 J/cm), 18 W at 3 s/cm (LEED 54 J/cm), 6 W interrupted pull-back 6 s stationary every 0.5 cm (LEED 72 J/cm). Thermal spread in the liver was measured via digital imaging. GSV sections were sent to an independent laboratory for histological analysis. Previous work suggests a thermal spread of >0.65 mm in liver correlates with transmural thermoablation of a GSV.Results: Parameters giving a LEED of 72 J/cm produced the best results, with a clear transmural effect in the GSV and maximal thermal spread of 1.65 mm, without excessive thermal damage or carbonisation in the ablation tract.Conclusions: Our porcine liver model correlated well with histological findings and was representative of the thermoablative effects observed in the GSV wall treated with RFiTT. Clinical investigations are now being carried out to investigate the efficacy of this protocol in the clinical setting.

Tu1150 Comparative Efficacy and Safety of Simplified (non-cleaning) and Standard Radiofrequency Ablation Protocols in Barrett’s Esophagus

A simplified radiofrequency ablation (RFA) protocol which eliminates the cleaning step between applications has been reported to be non-inferior and more efficient compared to the standard protocol in a small randomized trial in short BE segments. Data on long term outcomes in a larger cohort with longer BE segments are lacking. We aimed to compare the efficacy and safety of the simplified RFA protocol to the standard RFA protocol.

Feasibility of a Low-Power Radiofrequency Ablation Protocol to Delay Steam Popping

PurposeSteam popping frequently occurs during conventional high-power radiofrequency (RF) ablation, increasing the risk of tumor spread. The aim of this study was to evaluate the effect of a low-power RF ablation protocol on the intensity and timing of steam popping in ex vivo bovine liver. Materials and MethodsHigh-power (maximum 200 W; group 1) and low-power (maximum 70 W; group 2) RF ablation protocols were established. In the first phase, RF ablation was conducted for 12 min. Ablation volume, intensity, and timing of maximal popping sounds and total energy generated for RF ablation were compared between groups 1 and 2. In the second phase, RF ablation was conducted until maximal popping occurred, and ablation zones on histologic specimens were compared. ResultsRelative to group 1, maximal popping occurred at significantly delayed timing in group 2 (50 s ± 11 vs 397 s ± 117; P < .001), but without a difference in intensity (ratios vs reference sound of 0.70 ± 0.18 vs 0.83 ± 0.26; P = .138). The ablation volume after 12 min of RF ablation did not differ between groups 1 and 2 (18.46 cm3 ± 1.35 vs 15.78 cm3 ± 0.64; P = .086). However, in the histologic specimens obtained when maximal popping occurred, the area of complete coagulative necrosis was significantly larger in group 2 (P < .05). ConclusionsLow-power RF ablation delays steam popping while providing comparable therapeutic effects to high-power RF ablation. Delaying maximal popping may prevent tumor cell dispersion because maximal popping occurs after an adequate ablation zone has been achieved.

Safety and feasibility of endoscopic biliary radiofrequency ablation treatment of extrahepatic cholangiocarcinoma.

Biliary bipolar radiofrequency ablation (RFA) is a new treatment for extrahepatic cholangiocarcinoma (CCA) currently under evaluation. The purpose of this study was to evaluate the safety, particularly biliary fistula occurrence, and the feasibility of biliary RFA in a homogeneous group of patients treated using the same RFA protocol. Twelve patients with inoperable or unresectable CCA were included in a bicentric case series study. After removal of biliary plastic stents, a radiofrequency treatment with a new bipolar probe (Habib™ EndoHBP) was applied. The energy was delivered by a RFA generator (VIO 200 D), supplying electrical energy at 350 kHz and 10 W for 90 s. At the end of the procedure, one or more biliary stents were left in place. Adverse events were assessed per-procedure and during follow-up visits. CCA was confirmed in all patients by histology (66%), locoregional evolution or metastatic evolution. The types of CCA were Bismuth I stage (N = 4), Bismuth II stage (N = 3), Bismuth III stage (N = 2) and Bismuth IV stage (N = 3). No serious adverse events occurred within 30 days following endoscopic treatment: One patient had a sepsis due to bacterial translocation on day 1 and another had an acute cholangitis on day 12 due to early stent migration. No immediate or delayed biliary fistula was reported. The ergonomics of the probe made treatment easy in 100 % of cases. Mean survival was 12.3 months. Endoscopic radiofrequency treatment of inoperable CCA appears without major risks and is feasible. No major adverse events or biliary fistula were identified.

Study of the relationship between the target tissue necrosis volume and the target tissue size in liver tumours using two-compartment finite element RFA modelling

Purpose: The aim of this study was to investigate the relationship between the target tissue necrosis volume and the target tissue size during the radiofrequency ablation (RFA) procedure.Materials and methods: The target tissues with four different sizes (dxy = 20, 25, 30 and 35 mm) were modelled using a two-compartment radiofrequency ablation model. Different voltages were applied to seek the maximum target tissue necrosis volume for each target tissue size. The first roll-off occurrence or the standard ablation time (12 min) was taken as the sign for the termination of the RFA procedure.Results: Four different maximum voltages without the roll-off occurrence were found for the four different sizes of target tissues (dxy = 20, 25, 30 and 35 mm), and they were 36.6, 35.4, 33.9 and 32.5 V, respectively. The target tissues with diameters of 20, 25 mm can be cleanly ablated at their own maximum voltages applied (MVA) but the same finding was not found for the 35-mm target tissue. For the target tissue with diameter of 30 mm, the 50 °C isothermal contour (IT50) result showed that the target tissue can be cleanly ablated, but the same result did not show in the Arrhenius damage model result. Furthermore, two optimal RFA protocols with a minimal thermal damage to the healthy tissues were found for the target tissues with diameters of 20 and 25 mm, respectively.Conclusions: The study suggests that target tissues of different sizes should be treated with different RFA protocols. The maximum target tissue volume was achieved with the MVA without the roll-off occurrence for each target tissue size when a constant RF power supply was used.

Percutaneous ablation of functioning adrenal adenoma: a report on 11 cases and a review of the literature

Percutaneous ablation of functioning adrenal adenomas has been an alternative to videolaparoscopic treatment. This study aimed to evaluate the feasibility, safety and efficacy of radiofrequency ablation (RFA) in the treatment of functioning adrenal tumors using a computed tomography (CT)-guided percutaneous technique as demonstrated by our experience and the literature. Eleven adult patients (mean age 46 years) with a diagnosis of functioning adrenal adenoma underwent CT-guided RFA between October 2011 and August 2012. All RFA procedures were performed using a needle electrode with a single lateral filament and the RITA(®) 1500X radiofrequency generator. The RFA protocol consisted of two cycles of 5 min each with 1-min interval, with no additional ablation cycles. Contrast-enhanced CT scans were obtained and analyzed for immediate treatment success and possible complications. Maximum tumor dimension ranged from 1.2 to 3.4 cm. The mean procedure time was 74 min, and length of hospital stay ranged from 0.9 to 3.2 days (mean 1.8 days). One patient had residual pneumothorax and one patient had neuritis involving the T10 dermatome. Of 11 patients, 10 recovered from their condition. Only one patient remained with hyperaldosteronism, but with reduced anti-hypertensive medication. CT-guided percutaneous RFA was a safe and effective treatment for functioning adrenal adenomas, with short hospital length of stay and low complication rate.

Managing Barrett's esophagus with radiofrequency ablation.

Barrett's esophagus (BE) is a well-established pre-malignant lesion for esophageal adenocarcinoma, a condition that carries a dismal five-year overall survival rate of less than 15%. Among several available methods to eliminate BE, radiofrequency ablation (RFA) provides the most efficient modality, since it has been demonstrated to successfully eradicate BE with or without dysplasia with acceptable safety, efficacy and durability profiles. In conjunction with proton pump therapy, this new technology has quickly become the standard care for patients with dysplastic BE. However, several technical questions remain about how to deploy RFA therapy for maximum effectiveness and long-term favorable outcomes for all stages of the disease. These include how to select patient for therapy, what the best protocol for RFA is, when to use other modalities, such as endoscopic mucosal resection, and what should be considered for refractory BE. This review addresses these questions with the perspective of the best available evidence matched with the authors' experience with the technology.

Evaluation of theIn VivoEfficiency and Safety of Hepatic Radiofrequency Ablation Using a 15-G Octopus® in Pig Liver

ObjectiveTo determine in vivo efficacy of radiofrequency ablation (RFA) in porcine liver by using 15-gauge Octopus® (15-G Octopus®) electrodes to create a large coagulation.Materials and MethodsA total of 18 coagulations were created by using a 180-W generator and 15-G Octopus® electrodes during laparotomy, performed in 14 pigs. Coagulation necrosis was created in the pig livers by the use of one of three RFA protocols: 1) group A, monopolar RFA using a 15-G Octopus® electrode with a 5-mm inter-electrode distance (n = 4); 2) group B, monopolar RFA using a 15-G Octopus® electrode with a 10-mm inter-electrode distance (n = 6); and 3) group C, switching monopolar RFA using two 15-G Octopus® electrodes (n = 8). The energy efficiency, shape, maximum and minimum diameters (Dmx and Dmi), and the volume of the coagulation volume were measured in each group. The Summary statistics were obtained and Mann-Whitney test was were performed.ResultsThe mean ablated volume of each group was 49.23 cm3 in A, 64.11 cm3 in B, and 72.35 cm3 in C. The mean Dmx and Dmi values were 5.68 cm and 4.58 cm in A and 5.97 cm and 4.97 cm in B, respectively. In group C, the mean diameters of Dmx and Dmi were 6.80 cm and 5.11 cm, respectively. The mean ratios of Dmi/Dmx were 1.25, 1.20, and 1.35 in groups A, B, and C, respectively. There was one animal death during the RFA procedure, the cause of which could not be subsequently determined. However, there were no other significant, procedure-related complications during the seven-hour-delayed CT scans.ConclusionRFA procedures using 15-G Octopus® electrodes are useful and safe for creating a large ablation in a single electrode model as well as in the multiple electrodes model.