Pathway Ablation Research Articles

Effect of Transforming Growth Factor-β Inhibition on Ureteral and Renal Scarring in a Rat Model of Upper Urinary Tract Ablation with Irreversible Electroporation

Effect of Transforming Growth Factor-β Inhibition on Ureteral and Renal Scarring in a Rat Model of Upper Urinary Tract Ablation with Irreversible Electroporation

In-vivo mapping of human polymorphic ventricular tachycardia in Brugada syndrome

Abstract Background/introduction Brugada syndrome (BrS) is associated with ventricular fibrillation (VF) and polymorphic ventricular tachycardia (PMVT). Different mechanisms have been described for human PMVT, including epicardial drifting of rotational activity before stabilization on the apex. Purpose The aim of this study is mapping human PMVT mechanisms in BrS with ECG imaging (ECGI) in-vivo. Methods All BrS patients, were prospectively enrolled between 1992 and 2022. Inclusion criteria for the study were: 1) BrS diagnosis; 2) PMVT mapped with ECGI during thoracoscopic epicardial right ventricle outflow tract ablation. PMVT was adjudicated if a changing QRS pattern was present. Phase mapping was performed for each PMVT. All maps were imported on a dedicated software and analyzed offline. Left anterior descending coronary artery was added, based on CT scan reconstruction as a reference for the interventricular septum (in grey in Figure 1). Phase maps were performed using the Hilbert transform on detrended signals and the phases of wavefront propagation were color-coded. Rotational activity was defined as a continuous progression of phase from -π to +π around a phase singularity point. Focal activity was defined as a wavefront that appears de novo, without arising from another wavefront and spreading from its origin. Results A total of 21 BrS patients with VF were analyzed and 2 patients (9.5%) were found with PMVT. A total of 2 episodes of PMVT were mapped (one for each BrS patient) with a duration of 2.9 s and 1.3 s, respectively. Both PMVT had spontaneous initiation and termination. The mean number of rotational activities was 2.45 ± 0.07, with a mean of 2.9 ± 0.71 rotations on the apex and 0.8 ± 1.13 rotations on the septum. No other rotational activity was observed. There were 2 and 1 focal activities on the septum, respectively. No other focal activity was observed. The phase mapping of both PMVT episodes was consistent with the mechanism shown in Figure 1. In the first phase of PMVT (negative QRS) a stable rotor (white arrow) is found over ventricular apex (Figure 1, Panels A-D). In Figure 1, Panel E a septal activity appears (yellow arrow). The reduction of QRS voltage is secondary to a fusion between septal (yellow arrow) and apical (white arrow) rotational activities (Figure 1, Panels F-G). In the second phase of PMVT (positive QRS) a stable focal activity (yellow arrow) is found over the ventricular septum (Figure 1, Panels H-J). Conclusion In patients with BrS, change in the QRS pattern during PMVT is secondary to a fusion between rotational septal and apical activities.Figure 1

Experience of left ventricular outflow tract arrhythmia ablation in paediatric patients using limited fluoroscopy and three-dimensional mapping technique.

The left ventricular outflow tract is an important source of ventricular arrhythmias. Up to one-third of all idiopathic ventricular arrhythmias in patients with structurally normal hearts may arise from this region. We would like to share the results of our left ventricular outflow tract ablation using three-dimensional mapping and limited fluoroscopy. This is a single-centre retrospective cohort study. Forty-six consecutive patients who underwent left ventricular outflow tract ablation procedures between January 2015 and June 2023 were included in the study. The EnSite Precision System (Abbott, St. Paul, MN, USA) was used to facilitate mapping and to reduce or eliminate the need for fluoroscopy. The study group comprised 29 males and 17 females, with a mean age of 13.4 ± 4.5 years. The most common location for arrhythmias was the left coronary cusp (n : 21). Other locations, in sequence, included the junction of the right and left coronary commissure (n : 10), right coronary cusp (n : 10), left ventricular outflow tract endocardium (n:4), aorto-mitral junction (n : 1), and great cardiac vein (n : 1). Nine of these patients had previously undergone unsuccessful right ventricular outflow tract ablation at another centre. Cryoablation was performed in three patients, irrigated radiofrequency ablation in three patients, and conventional radiofrequency ablation in the remaining patients. The acute success rate was 100%, and no recurrences were observed. The mean follow-up period was 49.6 ± 24.4 months. All patients were asymptomatic and were being followed without antiarrhythmic medication. Although left ventricular outflow tract ablations pose a risk for coronary artery and heart valve complications, they can be performed successfully and safely with the guidance of three-dimensional mapping.

3D-Mapping Challenges in Hybrid Video-Assisted Thoracoscopic Surgical Ablation of Brugada Syndrome.

Brugada syndrome (BrS) is a life-threatening disease with an arrhythmogenic substrate located in the epicardium of right ventricle outflow tract (RVOT). Therefore, the correct region identification is crucial for a successful ablation procedure. Various mapping techniques can be adopted to elaborate this issue, but they were all initially developed for endovascular use. In this study we analyzed 21 consecutive hybrid video-assisted thoracoscopic (VATS) ablation of BrS, performed using different mapping systems to identify the ablation target and confirm the elimination of arrhythmogenic substrate; 35 maps have been analyzed. Acute success of epicardial RVOT ablation has been achieved in 100% of procedures, no periprocedural complications have been observed; HD Grid catheter showed higher area identification speed and faster fractionated potentials visualization; Rhythmia system has demonstrated the best map density; Carto3 system showed a significant advantage in patient preparation time, but mapping speed was reduced due to focal catheter use only. All tested electro anatomical mapping systems can be used for hybrid VATS ablation with same clinical success; however, accuracy and efficacy of mapping systems are heterogenous and highly dependent on proper patient preparation, mapping system and physician skills.

Analysis of the influencing factors associated with dyssynchrony and cardiac dysfunction in children with ventricular pre-excitation.

To investigate the correlation between ventricular pre-excitation-related dyssynchrony, on cardiac dysfunction, and recovery. This study included 76 children (39 boys and 37 girls) with a median age of 5.25 (2.67-10.75) years. The patients with pre-excitation-related cardiac dysfunction (cardiac dysfunction group, n = 34) had a longer standard deviation of the time-to-peak systolic strain of the left ventricle and larger difference between the maximum and minimum times-to-peak systolic strain than those with a normal cardiac function (normal function group, n = 42) (51.77 ± 24.70 ms versus 33.29 ± 9.48 ms, p < 0.05; 185.82 ± 92.51 ms versus 111.93 ± 34.27 ms, p < 0.05, respectively). The cardiac dysfunction group had a maximum time-to-peak systolic strain at the basal segments of the anterior and posterior septa and the normal function group at the basal segments of anterolateral and posterolateral walls. The prevalence of ventricular septal dyssynchrony in the cardiac dysfunction group was significantly higher than that in the normal function group (94.1% (32/34) versus 7.7% (3/42), p < 0.05). The patients with ventricular septal dyssynchrony (n = 35) had a significantly higher prevalence of intra-left ventricular systolic dyssynchrony than those with ventricular septal synchrony (n = 41) (57.1% (20/35) versus 14.6% (6/41), p < 0.05). During follow-up after pathway ablation, the patients who recovered from intra-left ventricular dyssynchrony (n = 29) had a shorter left ventricular ejection fraction recovery time than those who did not (n = 5) (χ2 = 5.94, p < 0.05). Among the patients who recovered, 93.1% (27/29) had a normalised standard deviation of the time-to-peak systolic strain and difference between the maximum and minimum times-to-peak systolic strain within 1 month after ablation. Ventricular pre-excitation may cause ventricular septal dyssynchrony; thus, attention must be paid to intra-left ventricular dyssynchrony and cardiac dysfunction. Whether intra-left ventricular systolic dyssynchrony can resolve within 1 month may be a new early predictor of patient prognosis.

CE-542-04 EASY-WPW: A NOVEL ECG-ALGORITHM FOR EASY AND RELIABLE LOCALIZATION OF MANIFEST ACCESSORY PATHWAYS IN CHILDREN AND ADULTS

Accessory pathway (AP) ablation is a standard procedure for the treatment of Wolff-Parkinson-White syndrome (WPW). 12-lead electrocardiogram (ECG) based delta wave analysis is essential for predicting ablation sites. Previous algorithms have shown to be complex, time-consuming and often unprecise because of variable anatomical heart axis especially in children. Our study aimed to retrospectively develop and prospectively validate a new, simple ECG-based algorithm considering the patients’ heart axis allowing an exact localization of APs in patients undergoing ablation for WPW. Our study included 109 patients undergoing ablation of a single manifest AP due to WPW between 2013 and 2021. For the exact determination of delta wave axis profound analyses of 12-lead ECGs were performed. The new algorithm (EASY WPW) includes a 2-step (left side) and 3-step-identification (right side) of the AP region, respectively. First we validated our algorithm comparing its efficacy to two established ones (Pambrun and Arruda). Then the new algorithm was tested also prospectively focusing on the accuracy of pathway region prediction. In all patients (29±18 years old, 45% female) pathway ablation was performed successfully. 12-lead ECG-based prediction of accurate AP localization using EASY-WPW was correct in 102 patients (94%) (sensitivity 93%, specificity 99%, PPV 97%, NPV 99%). Our algorithm was particularly useful in correctly localizing antero-septal/-lateral (sensitivity and specificity 100%) and posteroseptal (sensitivity 100%, specificity 91%) AP in proximity to the tricuspid valve. The accuracy (percentage of patients with an exact prediction of AP localization) of EASY-WPW was superior compared to the Pambrun (94% vs. 84%, p=0.049*) and the Arruda algorithm (94% vs. 75%, p<0.001*). A subgroup analysis of children (n=40, 11±4 years old, 45% female) revealed significant superiority to the Arruda algorithm (p=0.004*). Our novel 12-lead ECG-based algorithm enables reliable and accurate pre-interventional ablation site determination in WPW patients. Only two steps are necessary to locate left-sided AP and three steps to determine right-sided AP. This can be done with the help of a simple flow chart or, in the future, with the help of an app.

Comparison of PiLAT procedure and Crystallized Phenol Application in Pilonidal Sinus Surgery

Background: Pilonidal sinus disease (PSD) is an infectious, chronic and benign disorder of the sacrococcygeal area, predominantly encountered in young men. The surgical treatment of PSD has a wide range from minimally invasive interventions to complex flap techniques, however there is no agreement on the surgical approach. Minimally invasive procedures such as crystallized phenol (CP) application, sinusectomy, and pilonidal sinus tract ablation with laser (PiLAT) are easily applied, need a short hospital stay, cause less postoperative pain and minimal tissue loss, and have good cosmetic results. In this study, we aimed to compare the data of PSD patients treated with minimally invasive methods, namely CP and PiLAT. Material and Methods: The files of 245 PSD patients who were treated with the CP or PiLAT in our clinic between January 2016 and January 2020 were retrospectively reviewed. The patients were divided into two groups: 120 patients in the CP group and 125 patients in the PiLAT group. Both group were analyzed for age, gender, the number of sinuses, duration of surgery, severity of postoperative pain and need for analgesics, duration of antibiotic use, postoperative complications (infection, hematoma, seroma, cosmetic), time to return to daily activities, satisfaction for procedure, body mass index (BMI) and recurrence rates. Results: The patients in the PiLAT group were discharged the next day after the procedure, while the patients in the CP group discharged on the same day (p&lt;0.001). The mean number of sinuses was 2.2 ± 0.25 in the CP group and 3.6 ± 0.81 in the PiLAT group, and the difference was statistically significant (p&lt;0.001). The mean dressing time was 3.1 ± 0.4 days in the PiLAT group, while it was longer, 9.5 ± 2.1 days, in the CP group (p &lt;0.001). Conclusion: CP and PiLAT procedures are minimally invasive methods that can be safely used in the treatment of PSD. Keywords: Crystallized phenol, Minimally invasive, PiLAT, Pilonidal sinüs disease, Surgery

Administration of Adenosine Triphosphate Provides Additional Value Over Programmed Electrophysiologic Study in Confirmation of Successful Ablation of Atrioventricular Accessory Pathways.

Objectives: To study the benefit of adenosine triphosphate (ATP) in evaluating ablation endpoints of accessory pathways (AP) and subsequent long-term prognosis.Methods: We reviewed consecutive patients with supraventricular tachycardias due to APs that underwent radiofrequency catheter ablation (RFCA) from January 2016 to September 2018 in our center. The patients were divided into two groups: the ATP group (who had passed both the ATP test and PES after ablation as the endpoint) and the non-ATP group (who had passed PES only after ablation as the endpoint). We reviewed the patients' intra-cardiac electrograms and analyzed their long-term outcomes.Results: In total, 1,343 patients underwent successful RFCA. There were 215 patients in the ATP group with one lost to follow-up. There were 1,128 patients in the non-ATP group with 39 lost to follow-up. Twenty-three patients in the ATP group demonstrated additional electrophysiological entities due to ATP administration, including reappearance of the ablated APs in 16 patients, discovery of PES-undetected APs in 5, induction of atrial fibrillation in 5, premature atrial contractions in 1, and premature ventricular contractions in another. During the 7 to 39 months (average 24.4 ± 9.5 months) follow-up, the recurrence rate was 8.41% (18/214) in the ATP group and 6.80% (74/1,084) in the non-ATP group. In subjects with recurrence, 14 patients (14/18 = 77.8%) in the ATP group and 50 patients (50/74 = 67.6%) in the non-ATP group accepted redo ablations. Among the ATP-group, all the 14 redo APs were the old ones as before. Among the non-ATP-group, redo ablations confirmed that 39 APs were the old ones, while 20 APs were newly detected ones which had been missed previously. The difference in recurrent AP locations confirmed by redo procedures between the two groups was significant (p = 0.008). In the non-ATP group, 20 (40%) of redo cases were proven to have multiple APs, while 33 (3.3%) cases who did not suffer from recurrence had multiple APs. Existences of multiple APs in recurred cases were significantly higher than that in non-recurred ones in the non-ATP group (p < 0.001), while there was no such difference in the ATP group (p = 0.114).Conclusions: The existence of multiple APs was more common in recurrent cases if ATP was not used for confirmation of ablation endpoints. ATP probably has additional value over PES alone by detecting weak AP conductions. ATP can evoke atrial and ventricular arrhythmias.

Abstract 11186: A Case for Exercise-Induced Arrhythmogenic Right Ventricular Cardiomyopathy

Introduction: Sudden cardiac arrest has been documented in athletes, often secondary to left ventricular (LV) hypertrophy or previously undetected genetic conditions. Some athletes, however, experience these events without evidence of either LV or genetic disease. A hypothetical exercise-induced arrhythmogenic right ventricular cardiomyopathy (ARVC) has been previously described by La Gerche and colleagues, acquired through repeated, intense endurance exercise and associated cardiac remodeling rather than genetic inheritance. We present a case report of an endurance athlete presenting with ventricular tachycardia (VT), suspected to be secondary to exercise-induced ARVC. Results: A 40 year-old male endurance athlete was brought to the emergency department when he collapsed following a race in 2006. Upon arrival, he was in sustained wide-complex tachycardia at a rate of 200-220 BPM. Following conversion with IV amiodarone, left heart catheterization was performed, showing no significant coronary disease and LV ejection fraction (EF) measured 30-35%. He then underwent right ventricular outflow tract ablation. Cardiac MRI was inconclusive for ARVC. Biopsy was performed, negative for amyloidosis but with “focal mild to moderate chronic interstitial inflammatory infiltrates associated with focal muscle fiber necrosis.” Genetic testing was negative for pathologic variants or mutations associated with ARVC. Echocardiogram from 2020 showed EF 40-44% with significant RV enlargement and dysfunction. He required repeat VT ablation in 2010, 2014, and 2017. Arrhythmogenic scar was identified by electrophysiology mapping to be located at the sub-tricuspid RV. In combination with the prior RV outflow tract ablation, this is suggestive of the theoretical exercise-induced ARVC. Conclusions: There is still debate regarding right ventricular remodeling in endurance athletes. Increased volume and pressure in response to demand for cardiac output associated with this intense exercise has been proposed as a possible etiology of RV cardiomyopathy in athletes without identifiable genetic predisposition. Our case report supports this hypothesis.

Management and outcomes of atrial fibrillation in 241 healthy children and young adults: Revisiting "lone" atrial fibrillation-A multi-institutional PACES collaborative study.

Atrial fibrillation (AF) in healthy children and young adults is rare. Risk of recurrence and treatment efficacy are not well defined. The purpose of this study was to assess recurrence patterns and treatment efficacy in AF. A retrospective multicenter cohort study including 13 congenital heart centers was facilitated by the Pediatric & Congenital Electrophysiology Society (PACES). Patients ≤21 years of age with documented AF from January 2004 to December 2018 were included. Demographics, family and clinical history, medications, electrophysiological study parameters, and outcomes related to the treatment of AF were recorded and analyzed. Patients with contributory diseases were excluded. In 241 subjects (83% male; mean age at onset 16 years), AF recurred in 94 patients (39%) during 2.1 ± 2.6 years of follow-up. In multivariable analysis, predictors of AF recurrence were family history in a first-degree relative <50 years of age (odds ratio [OR] 1.9; P= .047) and longer PR interval in sinus rhythm (OR 1.1 per 10 ms; P= .037). AF recurrence was similar whether patients began no treatment (39/125 [31%]), began daily antiarrhythmic therapy (24/63 [38%]), or had an ablation at any time (14/53 [26%]; P = .39). Ablating non-AF substrate with supraventricular tachycardia improved freedom from AF recurrence (P = .013). Recurrence of AF in the pediatric population is common, and the incidence of recurrence was not impacted by "no treatment," "medication only," or "ablation" treatment strategy. Ablation of pathways and other reentrant targets was the only intervention that decreased AF recurrence in children and young adults.

Ablating Aspiration Needle Tract Prior to Microwave Ablation Can Improve Therapeutic Outcomes for Predominantly Cystic Thyroid Nodules.

PurposeTo investigate whether ablating the aspiration needle tract could improve the safety and efficacy of ultrasound-guided microwave ablation (MWA) for predominantly cystic thyroid nodules.Materials and MethodsThis retrospective study evaluated 41 predominantly cystic thyroid nodules that underwent MWA between June 2017 and August 2019. The nodules were stratified by different procedures into two groups: the aspiration needle tract was ablated before cyst fluid aspiration and MWA when treating 26 nodules in Group A, while the other 15 nodules in Group B underwent MWA directly after cyst fluid aspiration. Baseline characteristics, intervention time, hospital stays, nodules with intraoperative intracystic hemorrhage, and postoperative complications were compared between the two groups. Volume, volume reduction rate (VRR), compressive score (CS), and aesthetic score (AS) were evaluated during follow-up.ResultsBoth groups achieved decreases in volume, CS, and AS, as well as an increase in VRR. The volumes and VRRs in Group A at 1, 3, 6, and 12 months were significantly smaller and greater than those in Group B (p < 0.001). The incidence of intraoperative intracystic hemorrhage in Group A was significantly lower than that in Group B (p=0.035). Compared to Group B, hospital stays were much shorter in Group A (p=0.040). There were no significant differences in intervention time, cystic fluid volume or postoperative complications.ConclusionAspiration needle tract ablation dramatically reduces the incidence of intraoperative intracystic hemorrhage and markedly improves the efficacy of MWA for predominantly cystic thyroid nodules.

Abstract No. 120 Single-center large series of transpulmonary/transpleural hepatic tumor microwave ablation: safety and efficacy of the “lung seal technique”

Microwave ablation is a well-established intervention for treating primary liver cancer and metastatic lesions. For tumors located at high-risk locations such as the hepatic dome, however, some interventional radiologists take great caution in procedural planning to avoid pleural/pulmonary transgression. No guideline suggests that the transpleural/transpulmonary approach should be avoided at all costs. In this study, we retrospectively reviewed the outcomes of 52 transpleural MWAs, evaluating its safety, pulmonary complication rate, and long-term efficacy using “lung seal technique“ for tract ablation.

Laser-heated needle for biopsy tract ablation: In vivo study of rabbit liver biopsy.

To investigate the efficacy of a newly-developed laser-heated core biopsy needle in the thermal ablation of biopsy tract to reduce hemorrhage after biopsy using in vivo rabbit's liver model. Five male New Zealand White rabbits weighed between 1.5 and 4.0kg were anesthetized and their livers were exposed. 18 liver biopsies were performed under control group (without tract ablation, n=9) and study group (with tract ablation, n=9) settings. The needle insertion depth (~3cm) and rate of retraction (~3mm/s) were fixed in all the experiments. For tract ablation, three different needle temperatures (100, 120 and 150°C) were compared. The blood loss at each biopsy site was measured by weighing the gauze pads before and after blood absorption. The rabbits were euthanized immediately and the liver specimens were stained with hematoxylin-eosin (H&E) for further histopathological examination (HPE). The average blood loss in the study group was reduced significantly (p<0.05) compared to the control group. The highest percentage of bleeding reduction was observed at the needle temperature of 150°C (93.8%), followed by 120°C (85.8%) and 100°C (84.2%). The HPE results show that the laser-heated core biopsy needle was able to cause lateral coagulative necrosis up to 14mm diameter along the ablation tract. The laser-heated core biopsy needle reduced hemorrhage up to 93.8% and induced homogenous coagulative necrosis along the ablation tract in the rabbits' livers. This could potentially reduce the risk of tumor seeding in clinical settings.

Needle Tract Ablation in Liver Tissue Using a Cryoprobe Combined with an Electrosurgical Device: Influence of ex vivo and in vivo Animal Models.

To assess the feasibility of needle tract ablation in liver tissue in ex vivo and in vivo animal models using a cryo-probe and electrosurgical device. The experimental device is made by inserting a cryoprobe through an intro-ducer sheath for insulation, with 2-cm of probe tip projecting out. A beagle liver was punctured by the device, and electric current was applied at 30-W with the electrosurgical knife touching the non-insulated device base. The discolored area of cut surface along the device was evaluated in 5 application-time groups (5 , 10 , 15 , 20, or 25 seconds). An ex vivo experiment was performed to determine an ablation algorithm with an appropriate application time by comparison with radiofrequency ablation (RFA) results. Thereafter, an in vivo experiment was performed to verify the algorithm's feasibility. In the ex vivo model, the cut surface demonstrated different amounts of discolored area according to the application time. The total discolored area in the 20-seconds group was similar to that by RFA. In the in vivo model, the liver did not bleed, the total discolored area was similar to that ex vivo, and coagulation necrosis was confirmed by photomicrograph. Needle tract ablation can be per-formed using the experimental device and electrosurgical device.

Predictors of success for Brugada syndrome epicardial ablation

Abstract Epicardial right ventricular outflow tract (RVOT) ablation has been described for the treatement of Brugada syndrome (BrS) high risk patients. Purpose Success evaluation of epicardial ablation for BrS. Methods Type 1 ECG was defined as spontaneous if recorded in absence of drugs and/or specific conditions. BrS patients were scheduled for ablation if presented at least one of: spontaneous type 1 ECG, syncope, ventricular arrhythmias (VA). Programmed electrical stimulation (PES) was performed (2 extrastimuli, 2 sites) in basal conditions and after ajmaline infusion. Epicardial subxifoid access and electroanatomical endo-epicardial maps were obtained during sinus rhythm. Delayed fragmented/low-frequency, low-voltage electrograms (EGM) were targeted: substrate area measured in basal conditions and after ajmaline. Epicardial ablation Radiofrequency (RF) was delivered (50 W power control mode) till complete elimination of targeted EGM and BrS-ECG pattern after ajmaline. Eventually PES repeated: if positive a repeated PES scheduled at follow-up (fu). Success was defined as absence of type 1 ECG either spontaneous or with ajmaline challenge at 3 month. Recurrences were scheduled to redo ablation. Results 55 patients were submitted to 58 ablation procedures. 38 spontaneous type 1 ECG: 18 symptomatic for syncope/polimorphic VT/VF or appropriate ICD shock; 13 had VA induction at PES. 4 patients with ajmaline-type 1 ECG had VA induction. 36% of the symptomatic patients and 26% of asymptomatic had PES-VA induction. In all patients abnormal EGM area (cm2) was detected in epicardial RVOT (table 1). Acute success: No patient had ECG type 1 with ajmaline. 5 patients had PES induction of VA. Complications: 1 cardiac tamponade, 16 mild pericarditis. At FU of 1,1±0,6 yrs no patient had spontaneous ECG type 1 nor arrhythmic events. 50 had negative ajmaline challenge (90% success rate after single procedure), 3 underwent redo: 2 had negative ajmaline challenge at FU, 1 had persistence type 1-ajmaline induction; 2 are scheduled for redo. No patient had VT induction at PES. Multivariate analysis: Single procedure success was not related either to history (symptoms, VA, type 1 ECG) or to procedural findings (PES results, substrate area). Conclusion Epicardial substrate ablation was safe end effective in BrS. No clinical or procedural findings were related to success Funding Acknowledgement Type of funding source: None

Ablation of Accessory Pathways with Challenging Anatomy.

Although catheter ablation of accessory pathways is deemed highly safe and effective, peculiar location of these pathways might lead to complex and potentially hazardous procedures requiring ablation in anatomic regions such as para-Hisian area, coronary sinus, and epicardial surface. The electrophysiologist should know these possible scenarios to plan the best strategy for safe and effective ablation of these uncommon accessory pathways.

Impact of catheter-tissue contact force on lesion size during right ventricular outflow tract ablation in a swine model.

BackgroundThe catheter-tissue contact force (CF) is one of the significant determinants of lesion size and thus has a considerable impact on the effectiveness of ablation procedures. This study aimed to evaluate the impact of CF on the lesion size during right ventricular outflow tract (RVOT) ablation in a swine model.MethodsTwelve Guangxi Bama miniature male pigs weighing 40 to 50 kg were studied. After general anesthesia, a ThermoCool SmartTouch contact-sensing ablation catheter was introduced to the RVOT via the femoral vein under the guidance of the CARTO 3 system. The local ventricular voltage amplitude and impedance were measured using different CF levels. We randomly divided the animals into the following four groups according to the different CF levels: group A (3–9 g); group B (10–19 g); group C (20–29 g); and group D (30–39 g). Radiofrequency ablations were performed at three points in the free wall and septum of the RVOT in power control mode at 30 W for 30 s while maintaining the saline irrigation rate at 17 mL/min. At the end of the procedures, the maximum depth, surface diameter, and lesion volume were measured and recorded. A linear regression analysis was performed to determine the relationship between continuous variables.ResultsA total of 72 ablation lesions were created in the RVOT of the 12 Bama pigs. The maximum depth, surface diameter, and volume of the lesions measured were well correlated with the CF (free wall: β = 0.105, β = 0.162, β = 3.355, respectively, P < 0.001; septum: β = 0.093, β = 0.150, β = 3.712, respectively, P < 0.001). The regional ventricular bipolar voltage amplitude, unipolar voltage amplitude, and impedance were weakly positively associated with the CF (β = 0.065, β = 0.125, and β = 1.054, respectively, P < 0.001). There was a significant difference in the incidence of steam pops among groups A, B, C, and D (free wall: F = 7.3, P = 0.032; septum: F = 10.5, P = 0.009); and steam pops occurred only when the CF exceeded 20 g. Trans-mural lesions were observed when the CF exceeded 10 g in the free wall, while the lesions in the septum were non-trans-mural even though the CF reached 30 g.ConclusionsCF seems to be a leading predictive factor for the size of formed lesions in RVOT ablation. Maintaining the CF value between 3 and 10 g may be reasonable and effective for creating the necessary lesion size and reducing the risk of complications, such as steam pops and perforations.

Radiofrequency ablation of superoparaseptal-parahisian accessory pathways from the sinuses of Valsalva region: a three case report

Radiofrequency ablation of superoparaseptal-parahisian accessory pathways from the sinuses of Valsalva region: a three case report

A Temperature-Controlled Laser Hot Needle With Grating Sensor for Liver Tissue Tract Ablation

In this article, we proposed a laser hot needle for liver tissue tract ablation. The proposed laser hot needle is powered by a 4500-nm-diode laser incorporated with a closed-loop control system that comprises of a uniform fiber Bragg grating (FBG) temperature sensor and a computer. Based on the real-time feedback input from the FBG temperature sensor, the laser power is regulated by a proportional–integral–derivative (PID) control system to control the needle temperature. In the characterization test, a chirped grating-based distributed temperature sensor is employed for measuring the tissue temperature profile in the ex vivo bovine liver tissue during the ablation. A histological test is conducted to study the impact of tract ablation to the cellular structures of treated tissue and tissue coagulation. In a tract ablation test, a ~50-mm $\times \sim 6$ -mm (length $\times $ width) thermal denaturation zone has been created on ex vivo bovine liver tissue with the laser hot needle at 150 °C.

Tract ablation after radiofrequency ablation to prevent viable tumor cell adhesion to the needle electrode

Purpose To evaluate whether the additive needle tract ablation (TA) can reduce adherent cells on the needle tract after radiofrequency ablation (RFA) in a preclinical HCC mouse model. Methods Hep3B-Luc cells were engrafted in the Balb/c-nude mice. Nineteen mice were randomly assigned into three groups: the needle only group (needle placement only without performing RFA), the RFA only group (needle placement with active RFA treatment), and the RFA-TA group (needle placement with active RFA treatment and additive tract ablation). The 17-gauge needle with a 10-mm active tip was used. After RFA and TA, the viability of adherent tumor cells on the RFA needle was evaluated with bioluminescence imaging (BLI) and live-cell counting. Results We observed that RFA-TA group had the lowest BLI values compared with other groups (needle only group, 11.2 ± 6.4 million; RFA only group, 13.6 ± 9.1 million; RFA-TA group, 1.11 ± 0.8 million, p = 0.001). Live cell counting with acridine orange/propidium iodide staining also confirmed that the counted viable cell numbers in RFA-TA group were lowest compared to the other groups (needle only group, 14.8 ± 4.5; RFA only group, 643.8 ± 131.9; RFA-TA group, 1.5 ± 0.9, p < 0.001). Conclusions The additive tract ablation can significantly reduce the number of viable tumor cells adherent to the RFA needle, which can prevent needle tract seeding after RFA procedure.