Application Of Radiofrequency Energy Research Articles

Abstract P2101: Time Dependence Of Esophageal Injury With And Without Proactive Cooling During High-power Short-duration Radiofrequency Ablation

Background: Recent data suggest that luminal esophageal temperature (LET) monitoring during high-power short-duration (HPSD) ablation may be inadequate to prevent esophageal thermal injury during radiofrequency (RF) ablation. This is due in part to delayed responses to thermal latency and the continued temperature rise that occurs in tissues even after the cessation of RF energy with HPSD settings. Proactive esophageal cooling has been shown to reduce severe esophageal thermal injury during medium-power medium-duration RF ablation, but less is known about the effects in HPSD ablation. Objective: We aimed to quantify the time course of esophageal damage in scenarios with and without proactive esophageal cooling, hypothesizing a reduction in the resulting tissue damage with proactive esophageal cooling. Methods: Using a computer model of RF ablation in the left atrium adjacent to the esophagus, we calculated temperature over time using ablation power of 50 W for 10 s and 90 W for 4 s. We then determined the fraction of resulting damage to esophageal tissue via the Arrhenius equation and by the percentage of tissue above lethal isotherm temperature of 50°C. Transmurality of injury was then plotted over time, and results were compared between ablation with and without proactive esophageal cooling. Results: Esophageal damage increased even after the cessation of RF energy, suggesting significant thermal latency effects under HPSD ablation. Lesion growth continued for >10 s after cessation of 50 W ablation energy, and for >12 s after cessation of 90 W ablation energy without cooling. With proactive cooling, lesion growth after cessation of ablation energy was essentially halted. Without esophageal cooling, maximum injury transmurality reached 79% with 50 W, and 58% with 90 W. With esophageal cooling, injury transmurality remained below 20% with 50 W, and 10% with 90 W, representing reductions of 75% and 83%, respectively. Conclusions: RF ablation using HPSD settings demonstrates significant latency of effect, with tissue damage and lesion growth continuing beyond the cessation of application of RF energy. Proactive esophageal cooling significantly dampens this effect, reducing esophageal injury by up to 83%.

Inferior Vena Cava as a Trigger for Paroxysmal Atrial Fibrillation: Incidence, Characteristics, and Implications.

Identifying nonpulmonary vein triggers during atrial fibrillation (AF) ablation is of great importance. Currently, there are limited data on AF triggered by the inferior vena cava (IVC). This study was performed to investigate the incidence, characteristics, and implications of IVC triggers for AF. A total of 661 patients who underwent initial paroxysmal AF ablation were included. After pulmonary vein isolation, ectopic beats that triggered AF were further studied. Activation mapping and angiography were performed to confirm the location of ectopic origin. Electrocardiographic analysis of the ectopic P-wave (P'-wave) was performed. Six patients (0.91%) with AF triggered by the IVC were confirmed. The mean distance from the earliest activation site to the IVC ostium was 6.8 ± 2.5mm (5.2 to 11.2mm). Furthermore, the arrhythmogenic foci within the IVCwere all located at the apical hemisphere of the IVC (3 at the septal side and 3 at the anterior side). A total of 2.3±0.5 applications of radiofrequency energy were delivered to eliminate IVC triggers. The mean duration of the P'wave was 91.2 ± 11.2 milliseconds (81 to 108 milliseconds), which was narrower than that of the sinus P-wave (115.2±19.3 milliseconds [87 to 139 milliseconds]; P = 0.002). Moreover, the configuration of all P' waves in the inferior leads was negative. During a mean follow-up period of 25.5 ± 7.3months, all 6 patients remained arrhythmia free without antiarrhythmic drugs. IVC trigger, a rare but latent source of paroxysmal AF, could be identified and safely eliminated by focal radiofrequency ablation. Ectopic beats originating from the IVC presented with narrow P'-wave duration and negative P'waves in all inferior leads.

Use of Minimally Invasive Radiofrequency-Assisted Lipolysis as a Novel Treatment of Grade 2 and Grade 3 Cellulite.

Cellulite is a common condition, and laxity in the superficial fascial system contributes significantly to its appearance in the thigh and buttock areas. Components of the superficial fascial system such as the fibrous septae and adipose tissue are targets for an effective treatment to improve the appearance of cellulite. This preliminary report demonstrates the use of radiofrequency-assisted lipolysis as a novel treatment approach to improve the appearance of cellulite by tightening the superficial fascial system. Ten female patients with grade 2 and grade 3 cellulite of the thighs or buttocks were included in this study. Minimally invasive application of bipolar radiofrequency energy to the affected areas was performed. Predetermined internal thermal endpoints at multiple tissue levels and different directions were reached in the treated tissues. Aspiration of the coagulated adipose tissue was performed using a small-diameter cannula to minimize damage to the connective tissues. Pretreatment and 6-month postoperative photographs of 70 different body areas were randomized and scored by five blinded evaluators. Using the Photonumeric Cellulite Severity Scale, scoring of preoperative and postoperative photographs revealed statistically significant differences in all body area comparisons. The magnitudes of the differences in all scored body areas were considered large, and mean differences were all positive, indicating an improvement across time. Grade 2 and grade 3 cellulite of the thighs and buttocks can be effectively treated using radiofrequency-assisted lipolysis technology to decrease the laxity of the superficial fascial system.

A novel technique of pulmonary artery banding by means of radiofrequency ablation: An experimental study in rabbits.

Background The aim of this study was to evaluate the efficacy and feasibility of a novel method of narrowing pulmonary arteries with catheter angiography using radiofrequency energy in rabbits. Methods A total of nine New Zealand white rabbits weighing 3.0 to 4.2 kg each were utilized in this experimental study. After the location of pulmonary artery was confirmed by echocardiography and angiography, radiofrequency energy was applied by starting with 5 W energy for the first time and increasing by 5 W, if there was no rupture to a maximum of 20 W. Multiple applications of radiofrequency energy with different durations were performed at different levels of the pulmonary artery. Eight weeks later, surviving rabbits were sacrificed. The pulmonary arteries were removed for histological investigation. Results Five rabbits remained alive after the experiment. There was a significant correlation between radiofrequency power and the degree of vessel thickness change in the pulmonary artery. The endothelial integrity of the tunica intima was impaired in all groups and the diameter of vessel was thickened by an average of 3.5 times. Conclusion The narrowing of the pulmonary artery using radiofrequency energy was successfully performed in a small sample size of experimental animals in this study.

Endoskopická léčba refluxní nemoci jícnu pomocí radiofrekvenční energie (Stretta procedura) – ošetření prvních pacientů v České republice

Gastroesophageal reflux disease (GERD) is the most common disease of the gastrointestinal tract, affecting approximately a quarter of the European population with an increasing incidence. Some patients with GERD do not get full relief with conservative approach with proton pump inhibitors (PPI), while surgical solution is burdened with a significant percentage of complications and its effectiveness decreases over time. Endoscopic therapy of GERD currently includes five different methods, none of which have, to the knowledge of the authors, been more widely available and performed in the Czech Republic. The methods of electrical oesophageal stimulation, endoscopic fundoplication and Stretta have the potential to be used in practice. The latter method consists in the application of a low-frequency radiofrequency energy to the oesophagogastric junction (EGJ). According to the data published so far, it is probably a less effective alternative to laparoscopic fundoplication for patients with hiatal hernia ≤ 2 cm and failed conservative treatment, but its favourable safety profile, absence of EGJ anatomy alteration, repeatability and long-time effect in most patients are its undeniable advantages. On the other hand, the need to select suitable patients for the procedure and higher costs are among its disadvantages. Despite its limitations, Stretta offers an alternative option in the future for selected patients who would like to avoid the risks associated with long-term PPIs and are concerned about the risks of laparoscopic fundoplication. Keywords gastroesophageal reflux disease, endoscopic therapy, radiofrequency energy, Stretta

CATHETER-BASED RENAL DENERVATION – LONG TERM SAFETY AND BLOOD PRESSURE REDUCTION IN PATIENTS WITH RESISTANT HYPERTENSION

Objective: Recent sham-controlled andomised clinical trials have confirmed the safety and efficacy of catheter-based renal denervation (RDN) with clinically meaningful blood pressure (BP) reductions in hypertensive patients on or off antihypertensive medication. Longer-term safety and efficacy data have so far only been documented out to 3 years. Here we provide a first report on safety and efficacy outcomes in a cohort of patients with resistant hypertension beyond 5 years of follow up. Design and method: We recruited patients with resistant hypertension who were previously enrolled in various RDN trials applying radiofrequency energy to ablate the renal nerves using the Symplicity Flex® system. All participants had baseline assessments prior to RDN and repeat assessment at current long term follow up including medical history, automated office and ambulatory BP measurement, and routine blood and urine tests. Results: A total of 60 participants (age: 70.0 ± 10.3 years (mean ± SD), 76.3% male) have completed long-term follow up investigations with an average of 6.8 (range 6–10) years post-procedure. Ambulatory systolic BP was reduced by 12.0 ± 21.6mmHg (from 145.7mmHg to 132.8mmHg; p < 0.001) and diastolic BP by 8.3 ± 12.8mmHg (from 81.6 mmHg to 72.0 mmHg; p < 0.001). This BP reduction occurred despite participants being on less antihypertensive medication with a reduction in the average defined daily dose, the assumed average maintenance dose per day for a drug used for its main indication in adults, from 4.91 ± 0.37 to 4.02 ± 0.27 (p < 0.01). eGFR remained stable at long-term follow up with no statistically significant difference in participants with pre-existing CKD from baseline. Conclusions: Our investigation indicates a significant and robust reduction in ambulatory systolic and diastolic blood pressure, despite reduction in antihypertensive medications, in the long-term following catheter-based renal denervation without evidence of adverse consequences on renal function.

Influence of tissue thickness on thermal latency during high-power short-duration radiofrequency ablation with proactive esophageal cooling

Abstract Funding Acknowledgements Type of funding sources: None. Background Thermal latency, or delayed heating, is increasingly recognized as an important factor in the formation of both intentional and unintentional lesions during radiofrequency (RF) ablation for the treatment of atrial fibrillation (AF). High-power short-duration (HPSD) ablation appears to have greater thermal latency than low or medium power ablation. Proactive esophageal cooling (PEC) has been shown to reduce esophageal lesion formation under a variety of conditions by directly reducing the effects of thermal latency, but the influence of anatomic dimensions on the protective efficacy of cooling during HPSD ablation has not been investigated. Purpose Determine the impact of changes in pericardial tissue thickness on thermal latency in order to quantify the protective efficacy of PEC across a range of anatomic dimensions. Methods We created a mathematical model of the left atrium undergoing HPSD ablation, both with and without a PEC device in place, using a range of pericardial tissue thicknesses (0.5, 0.75, and 1 mm). HPSD ablation was set at 50 W for 10 s, or 90 W for 4 s. We then examined the temperature dynamics at a range of thickness, focusing on the layer of mostly fatty tissue between the atrial and esophageal walls by varying the thickness of this layer while quantifying the degree of esophageal damage using the Arrhenius equation to determine the fraction of damage after peak heating has occurred. Results Under control conditions, the growth of lesions from RF ablation at both 50 W and 90 W was found to continue for greater than 10 seconds beyond the cessation of RF energy application. Esophageal lesion formation ranged from 71% to 96% transmurality after 50 W ablation for 10 s, and from 50% to 72% transmurality after 90 W ablation for 4 s. With PEC in place, esophageal lesion transmurality was markedly reduced, with a maximum transmurality ranging from 12% to 32% with 50 W ablation, and from 2% to 20% with 90 W ablation (Figure). Increasing thickness of pericardial tissue (with simulations of 0.5, 0.75, and 1 mm) resulted in decreasing esophageal lesion transmurality (67%, 74%, and 83% at 50 W power, and 72%, 82%, and 96% at 90 W power, respectively, with the 0.5, 0.75, and 1 mm simulations). Conclusions Thermal latency with HPSD ablation contributes to lesion growth and can cause esophageal injury. Proactive esophageal cooling counteracts this effect across a range of pericardial tissue thicknesses, and reduces esophageal lesion transmurality by an average of 79%.

P4 LEFT ATRIAL APPENDAGE ANATOMICAL CHANGES FOLLOWING RADIOFREQUENCY–BASED OSTIAL ISOLATION

Abstract Background Left atrial appendage (LAA) electrical isolation (ei) may be achieved via radiofrequency (RF) energy applications at the level of the appendage ostium targeting the sites of earliest activation recorded by a mapping catheter. Notably, RF has long been used in vascular, orthopedic, and aesthetic surgery to promote thermal–induced collagen matrix contraction, fibrosis, and tissue retraction. LAA anatomical changes associated to RF–induced tissue retraction have never been reported. Objective To quantify the anatomical changes of the LAA ostium following RF–based LAAei. Methods Thirty–four consecutive patients requiring AF ablation with LAAei underwent transesophageal echocardiography (TEE) within 7 days before (baseline TEE) and >6 months after (follow–up TEE) ablation. The diameter of LAA orifice and landing zone were measured at 4 different views (0°, 45°, 90°, 135°). Measurements were performed by two independent reviewers blinded to the patient’s identity. Results Among 34 AF patients (68±7yrs, 73.5% males), the LAA morphology was classified as chicken wing in 15 (44%) patients, windsock in 10 (29%), cactus in 6 (18%), and cauliflower in 3 (9%). At baseline TEE, the mean maximum and mean minimum ostial diameters were 25±4mm and 22±4mm, respectively. The mean maximum and mean minimum diameters of the landing zone were 26±4mm and 23±3mm, respectively. On average, LAAei was achieved after 16±7 minutes of RF at a power of 45–47W. Follow–up TEE was performed 257±148 days after LAAei. The median LAA contraction velocity was 0.1 m/s (IQR: 0.04–0.18) and was significantly impaired in all patients. At follow–up TEE, the mean maximum and mean minimum ostial diameters were 19±4mm and 17±3mm, respectively. The mean maximum and mean minimum diameters of the landing zone were 20±4mm and 18±4mm, respectively. The mean relative reduction of the ostium and the landing zone were –24.4% and –22.5%, respectively. Box–Whisker plots of the maximum and minimum ostial diameters before and after LAAei are reported in Fig. 1. Conclusion RF led to a > 20% reduction of the diameters of the ostium and the landing zone. These changes may have important implications for a successful percutaneous occlusion procedure and justify a staged approach of isolation and occlusion.

PO-696-07 LEFT ATRIAL APPENDAGE ANATOMICAL CHANGES FOLLOWING RADIOFREQUENCY-BASED OSTIAL ISOLATION

Left atrial appendage (LAA) electrical isolation (ei) may be achieved via radiofrequency (RF) energy applications at the level of the appendage ostium targeting the sites of earliest activation recorded by a mapping catheter. Notably, RF has long been used in vascular, orthopedic, and aesthetic surgery to promote thermal-induced collagen matrix contraction, fibrosis, and tissue retraction. LAA anatomical changes associated to RF-induced tissue retraction have never been reported. To quantify the anatomical changes of the LAA ostium following RF-based LAAei. Thirty-four consecutive patients requiring AF ablation with LAAei underwent transesophageal echocardiography (TEE) within 7 days before (baseline TEE) and >6 months after (follow-up TEE) ablation. The diameter of LAA orifice and landing zone were measured at 4 different views (0°, 45°, 90°, 135°). Measurements were performed by two independent reviewers blinded to the patient’s identity. Among 34 AF patients (68±7yrs, 73.5% males), the LAA morphology was classified as chicken wing in 15 (44%) patients, windsock in 10 (29%), cactus in 6 (18%), and cauliflower in 3 (9%). At baseline TEE, the mean maximum and mean minimum ostial diameters were 25±4mm and 22±4mm, respectively. The mean maximum and mean minimum diameters of the landing zone were 26±4mm and 23±3mm, respectively. On average, LAAei was achieved after 16±7 minutes of RF at a power of 45-47W. Follow-up TEE was performed 257±148 days after LAAei. The median LAA contraction velocity was 0.1 m/s (IQR: 0.04-0.18) and was significantly impaired in all patients. At follow-up TEE, the mean maximum and mean minimum ostial diameters were 19±4mm and 17±3mm, respectively. The mean maximum and mean minimum diameters of the landing zone were 20±4mm and 18±4mm, respectively. The mean relative reduction of the ostium and the landing zone was -24.4% and -22.5%, respectively. Box-Whisker plots of the maximum and minimum ostial diameters before and after LAAei are reported in Fig.1. RF led to a >20% reduction of the diameters of the ostium and the landing zone. These changes may have important implications for a successful percutaneous occlusion procedure and justify a staged approach of isolation and occlusion.

Evaluation of Pilot-Scale Radio Frequency Heating Uniformity for Beef Sausage Pasteurization Process.

Radio frequency (RF) heating has the advantages of a much faster heating rate as well as the great potential for sterilization of food compared to traditional thermal sterilization. A new kettle was designed for sterilization experiments applying RF energy (27.12 MHz, 6 kW). In this research, beef sausages were pasteurized by RF heating alone, the dielectric properties (DPs) of which were determined, and heating uniformity and heating rate were evaluated under different conditions. The results indicate that the DPs of samples were significantly influenced (p < 0.01) by the temperature and frequency. The electrode gap, sample height and NaCl content had significant effects (p < 0.01) on the heating uniformity when using RF energy alone. The best heating uniformity was obtained under an electrode gap of 180 mm, a sample height of 80 mm and NaCl content of 3%. The cold points and hot spots were located at the edge of the upper section and geometric center of the sample, respectively. This study reveals the great potential in solid food for pasteurization using RF energy alone. Future studies should focus on sterilization applying RF energy and SW simultaneously using the newly designed kettle.

Predictors of antihypertensive efficiency of renal denervation. (Literature review)

Hypertension remains the leading cause of preventable cardiovascular disease and the main problem of overall mortality globally and also in Europe. Despite pharmacological advances, the control rates of blood pressure remain low worldwide and are far from being satisfactory in Europe. The renal sympathetic denervation is an innovative method, conceived 10 years ago, that involves the disruption of afferent and efferent renal sympathetic fibers by applying radiofrequency energy, thus reducing sympathetic activity and at the same time decreasing the blood pressure. Therefore, renal denervation expands the therapeutic options as being the first goal of hypertension treatment, which means the effective reduction of blood pressure values by achieving therapeutic targets.

Applying radiofrequency energy to the penis in the treatment of erectile dysfunction

Erectile Dysfunction is a major health concern with a deleterious effect on both men and partner. In the past decade a new concept of treating Erectile Dysfunction by applying energy to the penile tissue has been introduced and the recurrent use of low intensity shockwave therapy is used as an optional treatment for Erectile Dysfunction. Such a treatment results in penile micro-anatomical and physiological changes with relatively promising positive results on erectile function. Considering the significant role of the cavernosal tissue and the surrounding tunica albuginea in the erectile mechanism, we hypothesized that application of Radio Frequency to the penile tissue - a different form of low-energy, with its deep tissue warming effect and its established effect on restoration of collagen, will mainly cause both tunical and cavernosal changes via collagenesis and angiogenesis, and will potentially activate factors that facilitate erection (NO, VEGF etc.). Herein we describe how the application of a series of treatment sessions of RF energy on the penis may have a beneficial effect on recovery of erectile dysfunction and renewal of normal and satisfactory erections. Our hypothesis justifies the continuation of large-scale, double-blind, placebo-controlled clinical trials.

Recent developments in pasteurising seeds and their products using radio frequency heating: a review

AbstractFood‐borne or plant diseases mainly rely on the spread of seeds with pathogens. It is vital to eliminate food/seed‐borne pathogens of seeds and their products before commercial import/export or circulation. Radio frequency (RF) heating is identified as an effective method with lack of chemical residues, rapid or volumetric heating and large penetration depth, and also validated as a potential physical method to eliminate pests or pathogens in agricultural products or foods. Although, many reviews have summarised the applications of RF treatment during the process of foods, little comprehensive review has been focused on seeds and their products pasteurised by the RF energy. Comprehensive summary about principles and main applications of RF energy for pasteurising seeds and their products was reported in this review. This review also introduced some typical RF heating systems, thermal death kinetics of pathogens, influences of RF heating on germination rate of seeds and some ways for improving uniformity of RF heating. Furthermore, this review recommended the future research directions about treatment of seeds and their products using RF energy, especially for seed industry to control the pathogens in seeds without reducing their quality after RF treatments.

Radiofrequency Energy Applications Targeting Significant Residual Leaks After Watchman Implantation: A Prospective, Multicenter Experience.

The aim of this study was to evaluate the efficacy of radiofrequency (RF) energy applications targeting the atrial side of a significant residual leak in patients with acute and chronic evidence of incomplete percutaneous left atrial appendage (LAA) occlusion. RF applications have been proved to prevent recanalization of intracranial aneurysms after coil embolization, thereby favoring complete sealing. From a mechanistic standpoint, invitro and invivo experiments have demonstrated that RF promotes collagen deposition and tissue retraction. Forty-three patients (mean age 75 ± 7 years mean CHA2DS2-VASc score 4.6 ± 1.4, mean HAS-BLED score 4.0 ± 1.1) with residual leaks≥4mm after Watchman implantation were enrolled. Procedural success was defined as complete LAA occlusion or presence of a mild or minimal (1- to 2-mm) peridevice leak on follow-up transesophageal echocardiography (TEE), which was performed approximately 45days after the procedure. RF-based leak closure was performed acutely after Watchman implantation in 19 patients (44.2%) or scheduled after evidence of significant leaks on follow-up TEE in 24 others (55.8%). The median leak size was 5mm (range: 4-7mm). On average, 18 ± 7 RF applications per patient (mean maximum contact force 16 ± 3 g, mean power 44 ± 2 W, mean RF time 5.1 ± 2.5minutes) were performed targeting the atrial edge of the leak. Post-RF median leak size was 0mm (range: 0-1mm). A very low rate (2.3% [n=1]) of major periprocedural complications was observed. Follow-up TEE revealed complete LAA sealing in 23 patients (53.5%) and negligible residual leaks in 15 (34.9%). RF applications targeting the atrial edge of a significant peri-Watchman leak may promote LAA sealing via tissue remodeling, without increasing complications. (RF Applications for Residual LAA Leaks [REACT]; NCT04726943).

Abstract 9423: Virtual Reality (VR) Guided Telerobotic Cardiac Catheter Ablation is Feasible Over Low Bandwidth Network Connection

Introduction: Telerobotic operation in which a remote surgeon performs an operation over distance has long held the promise of providing a more equitable distribution of healthcare in rural and underserved regions of the world. One of the technological limitations that has hampered the adoption of telerobotic surgery is the need for a broadband connection to transmit high-resolution video of the operative field. Hypothesis: We hypothesized that we could develop a low-bandwidth system for telerobotic cardiac catheter ablation that deploys a virtual reality (VR)-based surgical guidance system to allow remote operation without the need for high-resolution video transmission. Methods: We assembled a portable pre-clinical telerobotic catheter ablation system from commercial-grade components by 3 rd party vendors. Raw sensor data from the catheter ablation system requiring a bitrate of less than 100kb/sec was streamed in real-time over distance using a standard internet connection. We used a proprietary service (DOPL Technologies, Seattle, WA) and an Oculus Quest (Oculus, Inc. Menlo Park, CA) to generate a shared, virtual operative field and operating room environment. No video data was transmitted. The Institutional Animal Care and Use Committee of the University of Washington (Seattle, WA) approved the study performed on a 14-week (27 kg) Yorkshire pig. The operator was located 6 miles from the OR at the time of the operation. Results: A successful proof of concept telerobotic cardiac catheter ablation in an animal model was performed without video transmission. The remote surgeon applied radiofrequency energy lesions in the animal’s cavotricuspid isthmus region. The visual depiction of the operative environment was successfully constructed in virtual reality from sensor data generated from the animal subject and surgical instruments. The remote operator conducted the ablation while interacting in a shared virtual OR environment with members of the surgical team present in the physical operating room and three remote observers. Conclusions: Telerobotic cardiac catheter ablation is feasible without video transmission. This approach could reduce network bandwidth requirements for telerobotic operations in rural areas.

Predictors of atrial fibrillation recurrence after surgical ablation of long-standing persistent AF with concomitant coronary artery bypass grafting

Abstract Background A long-standing persistent form of atrial fibrillation (AF) in anamnesis, requiring surgical ablation together with coronary artery bypass surgery (CABG), significantly increases the risk of reccurence in the postoperative period. Before operation should consider the predictors of AF for long-term preservation of rhythm after surgery. Purpose To evaluate the predictors of AF recurrence on 3rd day and at discharge in patients after CABG with concomitant surgical ablation of long-standing persistent AF. Methods A prospective randomized single-center analysis was performed on patients with long-standing persistent AF, undergoing CABG with concomitant left atrial ablation (LAA) or biatrial ablation (BA) between 2016 and 2019. 116 patients were randomized into two groups: 58 in LAA+CABG, 58 in BA+CABG. The median age of the patients was 65 (IQR, 61 to 67.75) years in gr. BA and 62 (IQR, 58 to 66) in gr. LAA (Mann-Whitney U-test, p=0.050), 83% of men were in gr. BA (Fisher test, p&amp;gt;0.999). Predictors of AF development on day 3 were identified using multivariable logistic regression from the following baseline characteristics: myocardial infarction in anamnesis, time of artificial circulation, time of application of radiofrequency energy, the size of the left and right atrium, funcrional class of cardiac angina and heart failure, gender, age, acute cerebrovascular accident (CVA), additional intervention on the heart (operations for aortic aneurysm, mitral, aortic and tricuspid valves replacement), concomitant cardiovascular, respiratory, digestive and urogenital diseases. Results Using a multivariate model of logistic regression, the following significant predictors of arrhythmias on the 3rd day in gr. BA were included: additional intervention on the heart valves (OR 63.13, p=0.001); an increase in the functional class (FC) of chronic heart failure (CHF) NYHA by 1 (OR 40.06, p=0.018); a history of CVA (OR 9.13, p=0.026). The following significant predictors of AF reccurence on the 3rd day in gr.LAA were identified: an increase in the long axis of the right atrium by 1 cm (OR 3.05, p=0.006); an increase of the FC of cardiac angina by 1 (OR 7.11, p=0.011); in women (OR 7.14, p=0.017). In BA significant predictors of AF reccurence at discharge were: an increase in the long axis of the left atrium by 1 cm (OR4.86, p=0.015); reccurence of AF on the 3rd day (OR 17.45, p=0.005); 1 year increase in age (OR 1.24, p=0.023); the presence of diabetes (OR 47.67, p=0.002). In gr. LAA the predictors at discharge were: reccurence of AF on 3rd day (OR 38.35, p=0.001); a history of CVA increases the chances of arrhythmia (OR 210.83, p=0.032). Conclusion Number of clinical and functional characteristics of a patient may be predictors of AF. We examined the predictors of reccurence of AF after surgical ablation of long-standing persistent AF with concomitant CABG. Taking them into account when choosing the optimal strategy of treatment is important. Funding Acknowledgement Type of funding sources: None.

The low acute effectiveness of a high-power short duration radiofrequency current application technique in pulmonary vein isolation for atrial fibrillation.

Application of high power radiofrequency (RF) energy for a short duration (HPSD) to isolate pulmonary vein (PV) is an emerging technique. But power and duration settings are very different across different centers. Moreover, despite encouraging preclinical and clinical data, studies measuring acute effectiveness of various HPSD settings are limited. Twenty-five consecutive patients with symptomatic atrial fibrillation (AF) were treated with pulmonary vein isolation (PVI) using HPSD. PVI was performed with a contact force catheter (Thermocool SF Smart-Touch) and Carto 3 System. The following parameters were used: energy output 50 W, target temperature 43°C, irrigation 15 mL/min, targeted contact force of > 10 g. RF energy was applied for 6-10 s. Required minimal interlesion distance was 4 mm. Twenty minutes after each successful PVI adenosine provocation test (APT) was performed by administrating 18 mg adenosine to unmask dormant PV conduction. All PVs (100 PVs) were successfully isolated. RF lesions needed per patient were 131 ± 41, the average duration for each RF application was 8.1 ± 1.7 s. Procedure time was 138 ± 21 min and average of total RF energy duration was 16.3 ± 5.2 min and average amount of RF energy was 48209 ± 12808 W. APT application time after PVI was 31.1 ± 8.3 min for the left sided PVs and 22.2 ± 4.6 min (p = 0.005) for the right sided PVs. APT was transiently positive in 18 PVs (18%) in 8 (32%) patients. Pulmonary vein isolation with high power for 6-10 s is feasible and shortens the procedure and ablation duration. However, acute effectiveness of the HPSD seems to be lower than expected. Further studies combining other ablation parameters are needed to improve this promising technique.

B-AB17-04 ELECTROPHYSIOLOGICAL FINDINGS IN PATIENTS UNDERGOING LEFT ATRIAL APPENDAGE OCCLUSION FOLLOWING PREVIOUS ELECTRICAL ISOLATION

Left atrial appendage electrical isolation (LAA) is an important adjunctive ablation strategy in patients with nonparoxysmal atrial fibrillation. If impaired mechanical function following isolation is observed, long-term oral anticoagulation (OAC) or, as an alternative, LAA occlusion are required. Although focal electrical potentials from the LAA do not result in normalization of appendage mechanical function, they may potentially be a source of arrhythmogenic triggers. Those focal areas might be challenging to ablate after Watchman implantation. We sought to report the incidence of focal electrical potentials in patients with a previously isolated LAA and transesophageal echocardiography (TEE) evidence of severely impaired LAA mechanical function undergoing Watchman implantation. In 97 patients undergoing Watchman 2.5 and Watchman FLX implantation following LAA isolation, a circular mapping catheter (CMC) was used before occlusion to document any residual LAA electrical activity. All patients had a severely impaired LAA mechanical function at pre-procedural TEE. Of 97 patients (mean age: 71±7 years; 61.9% males), 55 (56.7%) did not display any evidence of residual LAA electrical activity. In the remaining 42 (43.3%) patients, residual electrical potentials resulting in LAA reconnection were recorded on the CMC positioned into the appendage. On average, 4.6±1.2 radiofrequency energy applications (45W, mean duration of each RFA: 14.2±3.4s) were required to re-achieve complete isolation. Subsequent Watchman implantation was successful in all patients. Focal electrical activity from the LAA was documented in more than 1/3 of our patients. Although focal electrical potentials do not result in normalization of LAA mechanical function, they may potentially act as arrhythmogenic triggers. Since it may be challenging after device implantation, assessment and ablation of those areas should be considered before Watchman deployment.

B-AB04-03 RADIOFREQUENCY ENERGY APPLICATIONS TO TREAT INCOMPLETE LEFT ATRIAL APPENDAGE CLOSURE IN WATCHMAN PATIENTS WITH PERI- OR POST-PROCEDURAL EVIDENCE OF A SIGNIFICANT RESIDUAL LEAK

Incomplete left atrial appendage closure (LAA) due to significant residual leaks may be observed either acutely and/or chronically after Watchman implantation. Endothelial denudation by means of radiofrequency energy (RF) applications has been proven to prevent recanalization of intracranial aneurysms after coil embolization, thereby favoring complete sealing. In vitro and in vivo experiments have demonstrated that endothelial denudation promotes collagen deposition and tissue retraction. To evaluate the safety and efficacy of RF delivery targeting the atrial side of a significant residual leak in patients with acute and chronic evidence of incomplete percutaneous LAA occlusion. Forty-three patients (mean age: 75±7 yrs; CHA2DS2-VASc: 4.6±1.4; HAS-BLED: 4.0±1.1) with a significant residual LAA leak after Watchman implantation were enrolled. All had transesophageal echocardiographic (TEE) evidence of a leak ≥ 4mm after Watchman deployment and received multiple RFAs targeting the atrial side of the leak. Peri-Watchman ablation was performed under TEE/ICE guidance using a 3.5mm open irrigated-tip ablation catheter. Follow-up TEE was performed approximately 45 days after the procedure. Incomplete LAA occlusion was documented acutely after Watchman deployment in 19 (44.2%) patients, 4 (9.3%) of whom had a Watchman FLX implanted. In the remaining 24 (55.8%) patients, a significant residual leak was documented at the time of a routine follow-up TEE. The median leak size was 5mm (range: 4-7). On average, 18±7 RF applications per patient (mean max contact force: 16±3g, mean power: 44±2W, RF time: 5.1±2.5min) were performed targeting the atrial edge of the leak. Post-RF median leak size was 0 mm [0-2]. No peri-procedural complications were observed. Follow-up TEE revealed complete LAA sealing in 23 (53.5%) cases and a negligible residual leak (1-2mm) in 15 (34.9%). No device dislodgments or thromboses were documented. RF applications targeting the atrial edge of a significant peri-Watchman leak may promote LAA sealing via tissue remodeling, without increasing complications.

The impact of additional margin coagulation with radiofrequency in liver resections with subcentimetric margin: can we improve the oncological results? A propensity score matching study

BackgroundWhereas the usefulness of radiofrequency (RF) energy as haemostatic method in liver surgery has become well established in the last decades, its intentional application on resection margins with the aim of reducing local recurrence is still debatable. Our goal was to compare the impact of an additional application of RF energy on the top of the resection surface, namely additional margin coagulation (AMC), on local recurrence (LR) when subjected to a subcentimeter margin. MethodsWe retrospectively analyzed 185 patients out of a whole cohort of 283 patients who underwent radical hepatic resection with subcentimetric margin. After propensity score adjustment, patients were classified into two balanced groups according to whether RF was applied or not. ResultsNo significant differences were observed within groups in baseline characteristics after PSM adjustment. The LR rate was significantly higher in the Control than AMC Group: 12 patients (14.5%) vs. 4 patients (4.8%) (p = 0.039). The estimated 1, 3, and 5-year LR-free survival rates of patients in the Control and AMC Group were: 93.5%, 86.0%, 81.0% and 98.8%, 97.2%, 91.9%, respectively (p = 0.049). Univariate Cox analyses indicated that the use of the RF applicator was significantly associated with lower LR (HR = 0.29, 95% confidence interval 0.093–0.906, p = 0.033). The Control Group showed smaller coagulation widths than the AMC group (p < 0.001). ConclusionsAn additional application of RF on the top of the resection surface is associated with less local hepatic recurrence than the use of conventional techniques.