Radiofrequency Energy Ablation Research Articles

Posterior wall isolation with pulsed field ablation or radiofrequency ablation with vein of marshall ethanol ablation for the treatment of atrial fibrillation

Abstract Background In patients undergoing repeat catheter ablation for atrial fibrillation (AF) two ablation strategies beyond pulmonary vein isolation (PVI) have recently gained increased interest: posterior wall isolation (PWI) using pulsed field ablation (PFA) and Vein of Marshall (VoM) ethanol ablation combined with radiofrequency energy ablation (RFA). However, a direct comparison is lacking. Purpose To compare prospectively enrolled patients undergoing repeat catheter ablation for persistent AF using PVI and PWI with PFA (PFA group) vs. PVI and VoM ethanol ablation using RFA (VoM group) regarding procedural characteristics, safety, myocardial injury and outcomes. Methods Patients undergoing redo PFA-PVI with PWI and VoM ethanol ablation with RFA were included. Isolation and bidirectional block were checked using a multipolar mapping catheter. High-sensitivity cardiac troponin T (hs-cTnT) was measured after 24h of ablation. Results A total of 84 patients were included (age 69 [interquartile range (IQR) 63-75] years; ejection fraction 56% [IQR 48-60%]; left atrial size 42 [IQR 37-47] mm), baseline characteristics did not differ significantly between groups. Of these, 54 patients (64%) were in the PFA group and 30 (36%) in the VoM group. The procedure duration (65 [IQR 56-73] minutes vs 116 [IQR 103-142] minutes; p < .001) and fluoroscopic times (11 [IQR 8–14] minutes vs 14 [IQR 12-19] minutes; p < .001) were significantly shorter for the PFA group than for the VoM group. No major complications were observed except for a probable allergic reaction in the VoM group and a transient AV-block in the PFA group. High-sensitivity cardiac troponin levels post ablation were similar between the PFA group and the VoM group with 886 [IQR 627–1260] ng/L and 793 [IQR 543-1199] ng/L, p=0.28, respectively. During follow-up (median duration 230 [IQR 117-370] days), AF recurrence was observed in 15% in the PFA group and in 40% in the VOM group (p ≤ 0.01). Conclusion In patients undergoing repeat catheter ablation for AF, PVI and PWI using PFA is associated with shorter procedure and fluoroscopic times, similar high-sensitivity cardiac troponin levels and a reduced recurrence rate compared to PVI using RFA with additional VoM ethanol ablation.Central Illustration

Important parameters should be paid attention in PTMC radiofrequency ablation

In order to provide clinical references for the RFA procedure and to study the pivotal factors affecting the recovery time of radiofrequency ablation (RFA) in patients with papillary thyroid microcarcinoma (PTMC), 176 patients with low-risk intrathyroidal PTMC were included in this research. We randomly divided the whole cohort into training and test groups at a ratio of 7:3. The two-sample t-test was used to detect differences between the two groups. Least absolute shrinkage and selection operator (LASSO) regression was used to select the best predictor variables for predicting the status of RFA zone. Multiple test methods were used to ensure the scientific nature and accuracy of the Cox proportional hazards model. We tested the performance for the parameters and revealed the best cut-off value of each variable by the ROC curve and log-rank tests. The results showed patients aged above 49 years old, with RFA energy above 2800 J, the average diameter of the original tumour above 0.6 cm, or the average diameter of ablation zone at 1 month after RFA above 1.1 cm are risk factors for RFA zone delayed healing.

PO-03-042 A COOL DRINK OF WATER: CONVECTIVE ESOPHAGEAL COOLING PREVENTS THERMAL INJURY FROM RADIOFREQUENCY HEATING IN AN EX VIVO SWINE ESOPHAGUS MODEL

Esophageal heating and subsequent thermal injury are concerning adverse effects of radiofrequency (RF) energy ablation on the posterior wall of the left atrium. Active intraluminal esophageal cooling may provide thermal protection, allowing for effective delivery of RF energy to overlying myocardium without collateral damage to the underlying esophagus. To evaluate the impact of esophageal luminal cooling with a closed loop continuous flow irrigation on esophageal heating and thermal injury using an ex vivo model. A flexible tube was placed through the lumen of a swine esophagus and connected to a closed loop circuit consisting of a pump and water bath (Figure 1, panel A). The esophagus was submerged in a saline bath with a temperature of 36 °C and an impedance of 140 ohms. Ten non-contiguous RF lesions were delivered at 50 watts for 8 seconds directly on the outer esophageal wall with 4 mm irrigated RF ablation catheter. This was performed without irrigation (control), irrigation at 1.5 L/min with room temperature water (20 °C), and irrigation at 1.5 L/min with ice water (0 °C). Esophageal tissue samples were obtained from immunohistochemistry and the esophagus was cross sectioned and lesions were measured with digital calipers. Closed loop continuous flow esophageal irrigation with ice water yielded esophageal lesions with the smallest surface area (Figure 1, panel A), depth, and volume (Figure 1, panel B). Continuous esophageal irrigation with room temperature water resulted in the second smallest lesions. RF lesions without esophageal irrigation resulted in the largest and deepest lesion, as well as evidence of luminal esophageal injury (Figure 1, panel C & D). Histology showed preserved smooth muscle, glands, basement membrane and epithelium with cooled esophagus and transmural lesions with non-irrigated esophagus (Figure 1, panel C & D). Continuous endoluminal esophageal cooling reduced lesion size with RF energy delivery. There was no luminal injury with room temperature and ice water esophageal irrigation. Thus, both may be useful in prevention of endoluminal esophageal injury during poster wall RF ablation.

Clinical characteristics and electrophysiological features in patients with persistent atrial fibrillation undergoing radiofrequency energy ablation

Objective: To investigate the clinical and paraclinical characteristics and electrophysiological features after cardioversion in patients with persistent atrial fibrillation (AF). Subejct and method: This was a prospective study of 40 patients with persistent AF who underwent catheter ablation of AF using a three-dimensional (3D) system at the Vietnam Heart Institute, Bach Mai Hospital. Result: The mean age of the patients was 54.25 ± 12.54 years, and 80% of patients were male, the symptoms (according to EHRA) of patients ranged from grade IIb (67.5%) to grade III (32.5%). Hypertension (42.5%) and alcohol abuse (37.5%) were the most common risk factors. After cardioversion, patients with persistent AF exhibited longer sinus node recovery time (SNRT) (1445.11 ± 547.33ms) and corrected SNRT (667.03 ± 517.21ms) than healthy controls. Conclusion: Persistent AF is common in the elderly, especially men, with prevalent risk factors, such as hypertension and alcohol abuse. After cardioversion, patients with persistent AF have an SNRT longer than normal.

Safety and Feasibility of a Novel Externally Cooled Bronchoscopic Radiofrequency Ablation Catheter for Ablation of Peripheral Lung Tumours: A First-In-Human Dose Escalation Study

Background: Radiofrequency ablation (RFA) is an established modality for percutaneous ablation of non-small cell lung cancer (NSCLC) in medically inoperable patients but is underutilized clinically due to side effects. We have developed a novel, completely endobronchial RFA catheter with an externally cooled electrode. Objectives: The objective of this study was to establish the safety and feasibility of bronchoscopic RFA using a novel, externally cooled catheter for ablation of peripheral NSCLC. Methods: Patients with stage I biopsy-confirmed NSCLC underwent bronchoscopic RFA of tumour 7 days prior to lobectomy. The RFA catheter was delivered bronchoscopically to peripheral NSCLC lesions, guided by radial endobronchial ultrasound, with positioning confirmed using intra-procedural cone beam CT. Pre-operative CT chest and histologic examination of resected specimens were used to establish distribution/uniformity of ablation and efficacy of tumour ablation. Results: RFA in the first patient was complicated by dispersal of heated saline due to cough, resulting in ICU admission. The patient recovered fully and underwent uncomplicated lobectomy. Subsequently, the protocol was altered to mandate neuromuscular blockade with a pre-determined dose escalation, with algorithm-restricted energy (kJ) and irrigated saline volume (mL) constraints. A further 10 patients consented and seven underwent successful bronchoscopic RFA of peripheral NSCLC. No significant adverse events were noted. Ablation zone included tumour in all cases (proportion of tumour ablated ranged 8–72%), with uniform necrosis of tissue within ablation zones observed at higher energy levels. Ablation zone diameter correlated with RFA energy delivered (R² = 0.553), with maximum long axis diameter of ablation zone 3.1 cm (22.9 kJ). Conclusion: Bronchoscopic RFA using an externally cooled catheter is feasible, appears safe, and achieves uniform ablation within the treatment zone. Uncontrolled escape of heated saline poses a major safety risk but can be prevented procedurally through neuromuscular blockade and by limiting irrigation.

Validated Nomogram Predicting Clinical Outcome after Radiofrequency Ablation in the Treatment of Papillary Thyroid Microcarcinoma

Objective To establish a prediction model for the short-term efficacy of percutaneous ultrasound-guided radiofrequency ablation(RFA)in the treatment of papillary thyroid microcarcinoma(PTMC). Methods We retrospectively analyzed the preoperative and follow-up data of 159 patients with PTMC who underwent percutaneous ultrasound-guided RFA treatment in the Department of Ultrasound,the First Medical Center of Chinese PLA General Hospital from January to December in 2018.The association with 12-month tumor status(end event)was evaluated by multivariate logistic regression model.A nomogram was built to predict the risk of tumors which did not disappear completely within 12 months after RFA. Results We found that gender(P=0.017),age(P=0.047),and calcification(P=0.049)were the strongest predictors for establishing the model.The tumor maximum diameter and RFA energy were the secondary relevant factors for establishing the model.The constructed model showed good performance in both training cohort(AUC=0.762)and validation cohort(AUC=0.740). Conclusion A quantitative model was established for predicting the tumor status within one year after treatment of PTMC by RFA,which can accurately predict the short-term efficacy of RFA and provide a clinical basis for explaining the recovery results of patients.

Transcervical Radiofrequency Ablation of Uterine Fibroids Global Registry (SAGE): Study Protocol and Preliminary Results.

BackgroundTranscervical fibroid ablation (TFA) is a minimally invasive, effective treatment of symptomatic uterine fibroids that utilizes intrauterine ultrasound for imaging and radiofrequency energy for ablation. Outcomes reported with TFA have been positive, with significant reductions in fibroid volume, improvements in symptom severity and health-related quality of life, and low complication and surgical reintervention rates. The SAGE registry characterizes the long-term (5-year) outcomes of TFA when used to treat symptomatic uterine fibroids in real-world usage.Methods/DesignSAGE is an ongoing postmarket global registry involving up to 50 sites and up to 500 women who select TFA with the Sonata system for treatment of symptomatic uterine fibroids. Patients are followed for 5 years. Main outcomes include symptom severity score and health-related quality of life subscales of the UFS-QoL, general health status on the EQ-5D, perceived treatment benefit, treatment satisfaction, work and activity patterns, overall patient treatment outcome, adverse events, pregnancy incidence and outcomes, and surgical reinterventions for heavy menstrual bleeding.DiscussionThe SAGE registry represents the largest known study of TFA for uterine fibroids and will generate up to 2500 patient-years of outcome data. Preliminary results from the first 160 treated women suggest broad applicability of TFA to a wide range of fibroid types and sizes and an excellent safety profile, with a device-related adverse event rate of 0.6% and a serious procedure-related adverse event rate of 0.6%. Of the 241 fibroids treated, 10% were submucous, 52% transmural, 28% intramural, and 10% subserous. Ablated fibroid diameters ranged from <1 cm to >10 cm, with 27% of fibroids having maximum diameters >5 cm. The real-world experience from SAGE will strengthen the existing evidence on the durability of TFA in providing meaningful relief from uterine fibroid symptoms and will have important clinical and economic implications for patients, physicians, and healthcare payers.Trial Registrationhttps://clinicaltrials.gov, NCT03118037. Registered on 18 April 2017.

Endoscopic ultrasound-guided radiofrequency ablation of unresectable pancreatic cancer with low ablation power and multiple applications: a preliminary study of 11 patients.

Endoscopic ultrasound (EUS)-guided radiofrequency ablation (RFA) is a novel modality in the treatment of solid tumours. The aim of the study is to evaluate the technical feasibility, safety and efficacy of multiple-round EUS-RFA with low ablation power for unresectable pancreatic cancer. We conducted a retrospective analysis of eleven cases with unresectable pancreatic cancer who underwent EUS-RFA between November 2013 and November 2018. For each lesion, RITA 1500X radiofrequency generator was used to deliver 5-10 watts ablation power for 90 seconds, repeatedly. Eight cases underwent the same procedure one week later. Additionally, one patient with the lesion size of 29.7 mm underwent 8 total sessions of RFA every other week. The procedure was successful in all cases and no major adverse events were observed. The post procedure imaging studies and serum CA19-9 level were performed 1 month after procedure, showing two patients had decreased lesion sizes and five patients had decreased serum CA19-9 level. Follow-up duration ranged 2 to 12 months. The patient who underwent 8 total sessions of RFA survived 12 months after followup and showed increased tumour apparent diffusion coefficient (ADC) value and 20% ablated area inside the tumour. A multiple-round ablation with optimal RFA energy could be a technically feasible, safe and short-term efficacy option for those patients with unresectable pancreatic cancer.

Nomogram prediction for the involution of the ablation zone after radiofrequency ablation treatment in patients with low-risk papillary thyroid carcinoma

Objectives To construct a prognostic nomogram to predict the involution of the ablation zone for patients with low-risk papillary thyroid carcinoma (PTC) who underwent radiofrequency ablation (RFA) treatment. Methods Data from 204 patients with low-risk PTC without extrathyroidal extension or cervical lymph node or distant metastasis who underwent RFA treatment were collected from January 2018 to January 2019. Clinicopathological and imaging characteristics were analyzed. The prognostic factors associated with the involution of the ablation zone within 12 months after RFA were identified by logistic analysis, and the nomogram was established. Calibration curve and decision curve analysis were used to evaluate the nomogram performance. Results Of the 204 patients included in this study, the ablation zone in 78 (38%) patients did not completely disappear in the 12 months after RFA. Four variables, including sex (odds ratio [OR], 3.303; 95% confidence interval [CI], 1.418–8.418; p = 0.008), age (OR, 1.045; 95% CI, 1.012–1.081; p = 0.009), calcification size (OR, 1.666; 95% CI, 1.041–2.701; p = 0.035), and RFA energy (OR, 2.902; 95% CI, 1.333–6.683; p = 0.009), were found to be closely associated with ablation zone non-disappearance at 12 months after RFA by multivariate analysis. A nomogram model was constructed, and its accuracy was well validated (C-index = 0.787). Conclusions This study constructed and validated a risk model that could accurately predict the involution of the ablation zone after RFA for patients with PTC. This could provide clinicians with useful resource to guide patient counseling regarding tumor prognosis after RFA.

Inappropriate sinus tachycardia: a review.

Inappropriate sinus tachycardia (IST) has been defined as a resting heart rate of >100 beats per minute and an average 24-hour heart rate >90 bpm with distressing symptoms resulting from the persistent tachycardia. IST is prevalent in 1% of the middle-aged population, mostly females. Rarely can elderly patients also present with IST. Possible mechanisms of IST include intrinsic sinus node abnormality, beta-adrenergic receptor stimulating autoantibody, beta-adrenergic receptor supersensitivity, muscarinic receptor autoantibody, or hyposensitivity, impaired baroreflex control, depressed efferent parasympathetic/vagal function, nociceptive stimulation, central autonomic overactivity, aberrant neurohumoral modulation, etc. Symptoms associated with IST are palpitations, chest pain, fatigue, shortness of breath, presyncope, and syncope. Despite these distressing symptoms, IST has not been associated with tachycardia-associated cardiomyopathy or increased major cardiovascular events. Various treatment options for patients with IST are ivabradine, beta-adrenergic blockers, calcium channel blockers, psychiatric evaluation, and exercise training. Although, endocardial radiofrequency ablation targeting the sinus node has been used as a treatment modality for otherwise treatment-refractory IST, the results have been dismal. The other modalities used for refractory IST treatment are endocardial modification of the sinus node using radiofrequency energy, combined endo and epicardial ablation of the sinus node, thoracoscopic epicardial ablation of the sinus node, sinus node sparing thoracoscopic and endocardial hybrid ablation. The goal of this review is to provide the readership with the pathophysiological basis of IST and its management options.

The Mei mini-maze procedure.

Atrial fibrillation is a common clinical arrhythmia with high morbidity and a risk of stroke. The Cox-maze IV procedure that uses radiofrequency energy for ablation is established as an effective way to eliminate atrial fibrillation. Compared to the Cox-maze IV procedure, the video-assisted Wolf mini-maze procedure is associated with reduced surgical trauma, but still requires bilateral thoracotomies, and the ablation line connecting the right and left pulmonary vein isolations cannot be created with a bipolar ablation clamp. We have developed a novel video-assisted mini-maze technique that uses a unilateral (left chest) thoracoscopic approach (the Mei mini-maze procedure).

Abstract No. 505 Image-guided radiofrequency ablation of benign thyroid nodules: a literature review

The purpose of the study is to evaluate the efficacy, safety and utility of radiofrequency ablation (RFA) in the treatment of benign thyroid nodules (TNs). Four health databases were screened using a search strategy including MeSH terms from 2000-2018: PUBMED, EMBASE, WEB OF SCIENCE, and COCHRANE. Reference lists were manually reviewed. Studies identified were screened in duplicate in three stages: title review, abstract review and full-text review to determine eligibility. In 28 studies including 2639 patients, the ability of RFA treatment to reduce the volume of benign TNs ranged from 49.7% after 6 months to 93.5% after 48 months. Initial nodule volume was not predictive of RFA efficacy as it did not appear to correlate with volume reduction, while lower percent of solidarity in nodules was. With regards to number of RFA treatment sessions, RFA energy delivered per nodule volume, and training of RFA operators, there were many differences in the studies with no consensus or significant superiority being demonstrated. Regrowth of incompletely treated TNs poses a disadvantage to RFA treatment, occurring in up to 5.6% of some studies. There were no reports of life-threatening events; however, minor side effects of pain and a sensation of heat as well as infrequent complications of voice change, hematoma, vomiting, and skin burns did occur. This is in contrast to surgery, the traditional treatment of RFA, which has significantly more complications. RFA is an efficacious treatment of TNs with study results showing tremendous promise. Although some of the literature suggests treating smaller and cystic TNs with short and powerful sessions of RFA for greater efficacy, the effect of these factors still remains controversial. Further studies, with longer follow-up periods, are needed to continue elucidating the efficacy, safety, and techniques of RFA as well as the characteristics of TNs which would respond best to treatment. RFA might not necessarily replace surgery as of yet, although it would be a promising candidate. Instead, it can be an effective complementary or alternative treatment in TN management.

382 Esophageal Mucosal Impedance Measurement During Endoscopy: A New Approach to Diagnosis and Confirmation of Complete Remission of Intestinal Metaplasia Following Radiofrequency Ablation in Barrett’s Esophagus

INTRODUCTION: Mucosal impedance (MI), measured with a specialized balloon catheter at the time of upper endoscopy reveals a distinct pattern within the esophagus in patients with eosinophilic esophagitis and GERD. This novel technology may also be able to identify a unique profile in Barrett’s esophagus (BE) and confirm Endoscopic Complete Remission of Intestinal Metaplasia (ECRIM) following Radiofrequency energy ablation (RFA). AIM: Explore utility of MI in identification of BE and confirmation of ECRIM following RFA. METHODS: Patients (pts) with endoscopic and biopsy proven BE, most dysplasia undergoing RFA were prospectively enrolled. All were maintained on BID PPI. EGD noted top of gastric folds, SCJ, Prague criteria, hernia size and presence of nodules. Pts with nodular disease were excluded. RFA was performed per standard protocol and repeated until ECRIM achieved. Measurements were obtained with an MI balloon (Diversatek Healthcare, CO) 10 cm x 5 mm with two axial arrays of 10 sensors, throughout the entire BE segment and 5 cm above at pre-ablation EGD and following achieving ECRIM. At ECRIM endoscopic surveillance biopsies (q 1 cm; 4 quadrant) and WATS brushings were obtained to confirm CRIM. RESULTS: 16 pts 11M/5F, ages 26-71 years, all Caucasian were enrolled. BE length from 1-15 cm. (adenoca 1, LGD 5, HGD 5, indefinite1, Non dysplastic 4. To date, 7 pts have been studied prior to the initial RFA ablation and at ECRIM. 2 pts were studied only at end of RFA with ECRIM. 7 are in active treatment. MI measured within the BE segment ranged from 350-980 ohms pre RFA. (Normal &gt;2500, EoE, GERD &gt;1000). Post RFA MI measurements ranged from 1800- &gt;5000 ohms. 5/7 pts that achieved ECRIM had normalization of the MI pattern visualized (all values &gt;2500). The 2 pts that did not achieve normalization of the MI pattern demonstrated MI values consistent with inflammation in squamous tissue but no values suggestive of BE. Pathology confirmed absence of IM in all 9 pts. CONCLUSION/SUMMARY: 1) BE exhibits MI consistently &lt; 500 ohms and always below 1000 ohms, a unique MI profile not evident in GERD or EoE. 2) In pts who achieved ECRIM and biopsy and WATS proven CRIM following RFA ablation, the neosquamous esophageal mucosa exhibits a MI pattern similar to normal native squamous epithelium. Balloon catheter MI measurements can reliably identify BE epithelium and may be a valuable tool in assessment of post-RFA reversion to neosquamous epithielium and therefore successful BE ablation.

HRS 40th Anniversary Viewpoints: Historical aspects of the use of radiofrequency energy vs DC ablation to treat arrhythmias

HRS 40th Anniversary Viewpoints: Historical aspects of the use of radiofrequency energy vs DC ablation to treat arrhythmias

Treating Hypertension Using Renal Artery Denervation: Problems and Progress.

Early reports of renal denervation as a therapy for hypertension generated intense interest in this approach to management of elevated blood pressures despite ongoing treatment. The publication of the large, sham-controlled randomized clinical trial of renal denervation, Symplicity HTN-3, failed to show superiority of renal denervation by radiofrequency energy ablation compared with a sham procedure similar to the procedure used for denervation but without the application of energy to the renal artery. This prompted consideration of confounding factors and rethinking about the protocol and the procedure itself. This review describes these confounders and the progress made to improve trial design in the field of renal artery denervation.

His-Bundle Pacing for Identifying Optimal Ablation Sites in Patients Undergoing Atrioventricular Junction Ablation: Teaching an Old Dog a New Trick.

Atrioventricular (AV) junction (AVJ) ablation is conventionally performed by localizing the His-bundle electrogram (HBE). Identification of HBE in the presence of atrial fibrillation (AF) can be difficult, and can make this simple procedure challenging. In this study, we describe our experience with an alternative approach to localize optimal ablation sites using His-bundle pacing (HBP). Between 1/1/2014 and 12/31/2015, we performed 13 AVJ ablations using the standard electrogram-guided approach and 11 ablations using HBP. All cases utilized a long femoral guiding sheath and an 8-mm-tip electrode radiofrequency (RF) energy ablation catheter. Pacing was performed at high output (10 mA at 2 ms) to initially achieve right bundle branch capture. The catheter was withdrawn until a narrow QRS morphology and increased stim-to-QRS time were observed. HBP was confirmed when paced and native QRS were identical in morphology. RF energy was applied at the site of HBP capture until AV block was observed. Baseline characteristics of patients in each arm were not significantly different. Compared with the standard approach, HBP was associated with trends toward lower RF applications (3 vs. 2, P = 0.16) and shorter mean RF time (208 seconds vs. 128 seconds, P = 0.19). HBP is an effective technique to identify optimal ablation sites during AVJ ablation and may shorten procedure time. HBP can be used to identify the AV node during AF without recording the His potential. Future studies with larger sample size are needed to better characterize the utility of this technique.

OP-020 Meta-Analysis of Trials Comparing Cryothermal Energy and Radio Frequency Energy for Ablation of Isthmus Dependent Atrial Flutter

OP-020 Meta-Analysis of Trials Comparing Cryothermal Energy and Radio Frequency Energy for Ablation of Isthmus Dependent Atrial Flutter

Pulmonary Hemorrhage After Cryoballoon Ablation for Pulmonary Vein Isolation in the Treatment of Atrial Fibrillation

Pulmonary vein isolation has evolved over the past years as an alternative for the treatment of symptomatic recurrences of atrial fibrillation refractory to antiarrhythmic drug treatment. Both radiofrequency energy and cryoballoon ablation have proven useful in this setting. We present the case of a 55-year-old male patient undergoing cryoballoon ablation complicated with pulmonary hemorrhage. The cause of this rare complication may be found in the damage of vascular venous structures near the ablation zone or, alternatively, in hemorrhagic damage of the pulmonary vein surrounding tissue (or less probably to direct injury of the lingular bronchus). The extremely low temperatures achieved in this case (which are often associated with deep balloon position inside the veins) are alarming and should alert the physician about the possibility of an excessively intrapulmonary vein deployment of the cryoablation balloon.

Monopolar Radiofrequency Ablation Using a Dual-Switching System and a Separable Clustered Electrode: Evaluation of theIn VivoEfficiency

ObjectiveTo determine the in vivo efficiency of monopolar radiofrequency ablation (RFA) using a dual-switching (DS) system and a separable clustered (SC) electrode to create coagulation in swine liver.Materials and MethodsThirty-three ablation zones were created in nine pigs using a DS system and an SC electrode in the switching monopolar mode. The pigs were divided into two groups for two experiments: 1) preliminary experiments (n = 3) to identify the optimal inter-electrode distances (IEDs) for dual-switching monopolar (DSM)-RFA, and 2) main experiments (n = 6) to compare the in vivo efficiency of DSM-RFA with that of a single-switching monopolar (SSM)-RFA. RF energy was alternatively applied to one of the three electrodes (SSM-RFA) or concurrently applied to a pair of electrodes (DSM-RFA) for 12 minutes in in vivo porcine livers. The delivered RFA energy and the shapes and dimensions of the coagulation areas were compared between the two groups.ResultsNo pig died during RFA. The ideal IEDs for creating round or oval coagulation area using the DSM-RFA were 2.0 and 2.5 cm. DSM-RFA allowed more efficient RF energy delivery than SSM-RFA at the given time (23.0 ± 4.0 kcal vs. 16.92 ± 2.0 kcal, respectively; p = 0.0005). DSM-RFA created a significantly larger coagulation volume than SSM-RFA (40.4 ± 16.4 cm3 vs. 20.8 ± 10.7 cm3; p < 0.001). Both groups showed similar circularity of the ablation zones (p = 0.29).ConclusionDual-switching monopolar-radiofrequency ablation using an SC electrode is feasible and can create larger ablation zones than SSM-RFA as it allows more RF energy delivery at a given time.

Pulmonary vein isolation in patients with Brugada syndrome and atrial fibrillation: a 2-year follow-up

Pharmacological treatment of atrial fibrillation (AF) in the setting of Brugada syndrome (BS) might be challenging as many antiarrhythmic drugs (AADs) with sodium channel blocking properties might expose the patients to the development of ventricular arrhythmias. Moreover, patients with BS and implantable cardioverter-defibrillator (ICD) might experience inappropriate shocks because of AF with rapid ventricular response. The role of pulmonary vein isolation (PVI) in patients with BS and recurrent episodes of AF has not been established yet. In this study, we analysed the outcome of PVI using radiofrequency energy or cryoballoon (CB) ablation at 2 years follow-up. Consecutive patients with BS having undergone PVI for drug-resistant paroxysmal AF were eligible for this study. Nine patients (three males; mean age: 52 ± 26 years) were included. Six patients (67%) had an ICD implanted of whom three had inappropriate shocks because of rapid AF. At a mean 22.1 ± 6.4 months follow-up, six patients (67%) were free of AF without AADs. None of the three patients who had experienced inappropriate ICD interventions for AF had further ICD shocks after ablation. In our study PVI can be an effective and safe procedure to treat patients with BS and recurrent episodes of paroxysmal AF.