Substrate Ablation Research Articles

Catheter ablation of atrial fibrillation and atrial tachycardia in patients with pulmonary hypertension: a randomized study

Atrial fibrillation (AF), typical atrial flutter (AFL), and other atrial tachycardias (ATs) are common in patients with pulmonary hypertension. Frequently, several supraventricular arrhythmias are successively observed in individual patients. We investigated the hypothesis of whether more extensive radiofrequency catheter ablation of the bi-atrial arrhythmogenic substrate instead of clinical arrhythmia ablation alone results in superior clinical outcomes in patients with pulmonary arterial hypertension (PH) and supraventricular arrhythmias. Patients with combined post- and pre-capillary or isolated pre-capillary PH and supraventricular arrhythmia indicated to catheter ablation were enrolled in three centres and randomized 1:1 into two parallel treatment arms. Patients underwent either clinical arrhythmia ablation only (Limited ablation group) or clinical arrhythmia plus substrate-based ablation (Extended ablation group). The primary endpoint was arrhythmia recurrence >30 s without antiarrhythmic drugs after the 3-month blanking period. A total of 77 patients (mean age 67 ± 10 years; 41 males) were enrolled. The presumable clinical arrhythmia was AF in 38 and AT in 36 patients, including typical AFL in 23 patients. During the median follow-up period of 13 (interquartile range: 12; 19) months, the primary endpoint occurred in 15 patients (42%) vs. 17 patients (45%) in the Extended vs. Limited ablation group (hazard ratio: 0.97, 95% confidence interval: 0.49-2.0). There was no excess of procedural complications and clinical follow-up events including an all-cause death in the Extended ablation group. Extensive ablation, compared with a limited approach, was not beneficial in terms of arrhythmia recurrence in patients with AF/AT and PH. ClinicalTrials.gov; NCT04053361.

Trigger and Substrate Mapping and Ablation for Ventricular Fibrillation in the Structurally Normal Heart.

Sudden cardiac death (SCD) represents approximately 50% of all cardiovascular mortality in the United States. The majority of SCD occurs in individuals with structural heart disease; however, around 5% of individuals have no identifiable cause on autopsy. This proportion is even higher in those <40 years old, where SCD is particularly devastating. Ventricular fibrillation (VF) is often the terminal rhythm leading to SCD. Catheter ablation for VF has emerged as an effective tool to alter the natural history of this disease among high-risk individuals. Important advances have been made in the identification of several mechanisms involved in the initiation and maintenance of VF. Targeting the triggers of VF as well as the underlying substrate that perpetuates these lethal arrhythmias has the potential to eliminate further episodes. Although important gaps remain in our understanding of VF, catheter ablation has become an important option for individuals with refractory arrhythmias. This review outlines a contemporary approach to the mapping and ablation of VF in the structurally normal heart, specifically focusing on the following major conditions: idiopathic ventricular fibrillation, short-coupled ventricular fibrillation, and the J-wave syndromes-Brugada syndrome and early-repolarization syndrome.

PO-01-204 AN ARTIFICIAL INTELLIGENCE (AI)-ASSISTED END-TO-END COMPUTATIONAL PLATFORM FOR PREDICTION OF EXTRA-PULMONARY VEIN (EXTRA-PVI) ABLATION TARGETS IN ATRIAL FIBRILLATION (AF) PATIENTS WITH FIBROSIS REMODELING

Existing strategies targeting the extra-PVI AF substrate have failed to improve outcomes, as shown by clinical trials. There is an urgent need to establish new approaches that overcome existing limitations. We have shown previously, in a feasibility study, that bi-atrial personalized computational modeling can guide ablation in patients with fibrosis detected on late gadolinium enhancement MRI (LGE-MRI). However, the approach had laborious aspects, such as segmentation of both atria and fibrosis distribution, and determining substrate locations capable of sustaining rotors. These prevented the approach from being directly implementable in clinical workflows. To develop an AI-assisted computational platform for personalized extra-PVI substrate ablation target prediction in patients with atrial fibrosis detected by LGE-MRI, as part of an FDA-approved randomized clinical trial. We designed an AI-assisted platform enabling end-to-end modeling workflow for predicting extra-PVI ablation targets. The platform consists of 3 main components (Figure): i) personalized bi-atrial model construction from LGE-MRI, ii) personalized simulation of substrate AF inducibility, and iii) personalized extra-PVI ablation strategy implementable in the clinical workflow. For the first component, we developed, validated, and tested a deep learning approach to bi-atrial geometry and fibrosis segmentation, which consisted of a cascade of 4 neural networks (NNs). Extra-PVI substrate rotor inducibility was probed by pacing from numerous sites; locations capable of sustaining persistent drivers were determined using a novel NN approach and ablated. Each ablation was followed by the inducibility test, repeated until full substrate non-inducibility from any pacing site was achieved. The platform was successfully tested on 17 AF patients by multiple operators of differing expertise, with consistent results. Atrial geometry/fibrosis segmentation was achieved in 15 min, as compared to 5 hours pre-AI implementation. Using the NN approach for targeted substrate ablation ensured robustness and reproducibility of the predicted targets. Finally, a seamless import of atrial geometry and the optimal set of targets was achieved in a number of EAM systems. We developed a robust AI-assisted computational platform for prediction of extra-PVI atrial substrate ablation targets in AF patients with fibrosis, enabling our FDA-approved randomized clinical trial.

PO-05-001 TARGETING WAVEFRONT DISCONTINUITY LINES FOR SCAR-RELATED VENTRICULAR TACHYCARDIA ABLATION

Late activation mapping can identify wavefront discontinuities during functional substrate mapping. Automated visualization of wavefront discontinuity lines (WaDLs) representing conduction block or delay may be a suitable target for a focused VT ablation. To describe WaDLs in multiple types of cardiomyopathy undergoing VT ablation, with correlation to critical VT circuit sites and bipolar low voltage scar. Patients who underwent high density substrate ablation with late activation mapping in sinus or paced wavefront were retrospectively analyzed. An automated mapping algorithm was used to visually demarcate WaDLs by identifying adjacent points where mapped activation times were greater than a certain timing threshold (CARTO®,Biosense Webster) Extended Early Meets Late module). Timing threshold was set to 25-35% of the mapped activation time. The number, total length, and distance to critical VT site of WaDLs was compared at each threshold 34 patients (20 post-infarct, 10 dilated, 1 Chagas, 1 sarcoid, 1 ARVC, 1 lamin) with 46 endocardial or epicardial surface substrate maps (10 epicardial, 36 endocardial; mean 1898 points) were included. WaDLs were present in each cardiomyopathy and surface, and represented average timing discontinuities of 50-61 ms (25%-35% WaDL threshold) with no difference in number or length of WaDLs by the mapped chamber, cardiomyopathy type, or wavefront. Parallel WaDLs forming putative channels were present in 37.2% of mapped chambers. In 15 patients with a critical VT site identified, the median distance from critical site to nearest WaDL was 7.4 mm (IQR 2.2-18.6 mm), with shorter distances on the epicardial surfaces compared to endocardial (1.4 vs 13.9 mm at 30% WaDL, P = 0.015). Functional substrate ablation in this cohort covered a mean 26% of the bipolar low voltage scar area (< 1.5 mV). Automated WaDLs represent easily visualized significant discontinuities that correlate with clinical VT circuits, are present in a wide variety of cardiomyopathy types and both epicardial and endocardial surfaces. Targeting WaDLs requires a smaller ablation area than low voltage homogenization.

PO-02-099 RADIOFREQUENCY CATHETER ABLATION OF ATRIAL TACHYCARDIA AND ATRIAL FIBRILLATION IN PATIENTS WITH PULMONARY HYPERTENSION. A SUBANALYSIS OF A PROSPECTIVE RANDOMIZED TRIAL

Atrial fibrillation (AF) and related atrial tachycardias (AT), including typical atrial flutter (AFL), are common arrhythmias in patients with pulmonary hypertension (PH). We have shown, in the multicenter randomized trial, that extensive radiofrequency catheter ablation of the arrhythmogenic substrate on top of selective ablation of clinical arrhythmia alone was not beneficial in terms of arrhythmia recurrence in patients with AF / AT and PH. Irrespective of the randomization scheme, we compared clinical outcomes in patients with AF versus those with organized ATs. Out of 74 patients (42 males; the median age of 70 [IQR 61; 75] years) with combined post- and pre-capillary or isolated pre-capillary PH enrolled at 3 national sites, two study subgroups were composed: the AF group and the AT group (including AFL). The primary endpoint was arrhythmia recurrence >30 s without antiarrhythmic drugs after the 3-month blanking period. Idiopathic pulmonary arterial hypertension was found in 41 (55%) patients, chronic thromboembolic PH in 22 (30%), and PH associated with lung disease or hypoxia in 11 (15%). The AF group included 38 patients, and AT group included 36 patients (23 with AFL). The median duration of the follow-up period was 13 (IQR: 12; 21) months. The primary endpoint occurred in 23 patients (61 %) with AF vs. 9 patients (25 %) with AT (hazard ratio: 0.3, 95% confidence interval: 0.14-0.66; p = 0.003), Figure. In contrast to AF and other organized ATs, typical AFL did not reoccur during the follow-up. Out of 4 patients with documented arrhythmia after cavotricuspid isthmus ablation, 2 had AF and 2 patients manifested atypical AFL. More details are in the Table. Patients with PH and organized ATs manifested less frequent reoccurrence of arrhythmia after catheter ablation than patients with AF. Despite new arrhythmia could manifest, catheter ablation seems to be the most effective in PH patients with typical AFL. ClinicalTrials.gov Identifier: NCT04053361. Funding: The study was supported by the Ministry of Health of the Czech Republic, Grant Nr. NV18-02-00027.

AB-452666-2 CATHETER ABLATION OF ATRIAL FIBRILLATION AND ATRIAL TACHYCARDIA IN PATIENTS WITH PULMONARY HYPERTENSION: A RANDOMISED STUDY

Atrial fibrillation (AF), typical atrial flutter (AFL), and other atrial tachycardias (ATs) are common in patients with pulmonary hypertension. Frequently, several supraventricular arrhythmias are successively observed in individual patients. We investigated the hypothesis of whether more extensive radiofrequency catheter ablation of the bi-atrial arrhythmogenic substrate instead of clinical arrhythmia ablation alone results in superior clinical outcomes in patients with PH and supraventricular arrhythmias. Patients with combined post- and pre-capillary or isolated pre-capillary PH and supraventricular arrhythmia indicated to catheter ablation were enrolled in 3 centres and randomised 1:1 into two parallel treatments arms: (A) Clinical arrhythmia ablation and (B) Clinical arrhythmia plus substrate-based ablation. The primary endpoint was arrhythmia recurrence >30 s without antiarrhythmic drugs after the 3-month blanking period. A total of 77 patients (mean age 67 ± 10 years; 41 males) were enrolled. The presumable clinical arrhythmia was AF in 38 and AT in 36 patients, including typical AFL in 23 patients. During the median follow-up period of 13 (IQR: 12; 19) months, the primary endpoint occurred in 15 patients (42 %) vs. 17 patients (45 %) in the group B vs. A (hazard ratio: 0.97, 95% confidence interval: 0.49-2.0). There was no excess of procedural complications and clinical follow-up events including an all-cause death in group B. Extensive ablation, compared with a limited approach, was not beneficial in terms of arrhythmia recurrence in patients with AF / AT and pulmonary hypertension. ClinicalTrials.gov Identifier: NCT04053361. Funding: The study was supported by the Ministry of Health of the Czech Republic, Grant Nr. NV18-02-00027.

PO-01-101 INDUCIBILITY AND MAINTENANCE OF PEDIATRIC & ADULT CONGENITAL ARRHYTHMIAS USING A MODIFIED INHALATIONAL ANESTHETIC STRATEGY

Controversy exists regarding the most appropriate anesthetic strategy to maximize the possibility of arrhythmia induction/maintenance in those individuals requiring general anesthesia for the ablation of arrhythmia substrates. The anesthetic regimen used at our facility consists of a light combined inhalational (sevoflurane) and intravenous (midazolam/fentanyl) general anesthesia (GA), hypercarbia, normothermia (37.0 C), and mostly spontaneous breathing. We investigated the rate of arrhythmia inducibility with this anesthesia strategy. To study the rate of inducibility and maintainence of arrhythmias with the anesthetic regimen used at our facility. A single center retrospective study was performed. Data from subjects 2-44 years undergoing elective electrophysiology study (EPS) for evaluation of supraventricular tachycardia, ectopic atrial tachycardia, premature ventricular contractions (PVC)/ventricular tachycardia (VT) or WPW (Wolff-Parkinson-White) from 2020 to 2022 were included. The primary outcome was positive EPS, defined as successful induction of clinical tachyarrhythmias. 134 subjects were evaluated: 57% male; mean age 14.5+/-6.3 years, 10% adult (age above 18 years). EPS conducted for documented arrythmia of SVT 46%, atrial tachycardia 4%, atrial flutter 7%, PVC 3%, VT 5%, A fib 1%, and WPW 32%. A positive EPS occurred in 74% of cases overall. Arrhythmia was induced in 85% of adult subjects versus 73% of children (p=0.37), and in 70% male versus 79% of female subjects (p=0.23). When arrhythmias were documented, they were inducible in 94.4% of cases; when there was no antecedent history of arrhythmias (such as asymptomatic WPW), they were still induced 36.9% (p<0.001). Overall, a positive EPS occurred in 52% of WPW cases. PVCs and VT remained present after anesthesia (or were inducible by pharmacologic/pacing maneuvers) in 100% of cases. Selected assessment of refractory periods during post-ablation protocols suggests that hypercarbia may be one of the key components of the strategy, with a lowering of AV nodal refractory periods of as much as 40 msec. Our data suggests that an inhalational anesthetic strategy is extremely effective at maintaining arrhythmia inducibility when combined with other strategies that preserve cardiac excitability and refractory periods. Additionally, this strategy may be more effective for the induction and maintenance of arrhythmias in PVC/VT cases.

PO-05-232 SAFETY AND EFFICACY OF ATRIOVENTRICULAR NODAL REENTRY TACHYCARDIA ABLATION USING AN IRRIGATED CONTACT FORCE CATHETER

Atrioventricular Nodal Reentry Tachycardia (AVNRT) ablation is a common procedure in contemporary electrophysiology practice. Traditionally ablation for AVNRT has been performed with non-irrigated catheters, guided by fluoroscopy and intracardiac electrograms. Increasingly electroanatomic mapping systems are utilized to allow for low or zero fluoroscopy procedures. Contact force catheters can provide information on tissue contact and stability that can be helpful in patients with challenging anatomy. Available contact force catheters are irrigated and concern has existed for using irrigated tip ablation catheters for AVNRT ablation due to the potential to create lesions that are too deep and could increase the risk for AV block. To describe the safety and efficacy for the use of irrigated contact force catheters for ablation of AVNRT Review of procedural data from patients undergoing radiofrequency ablation for AVNRT using electroanatomical mapping combined with irrigated contact force catheter. Fifty patients from 4 regions across Australia were included. Procedures were performed by 9 experienced electrophysiologists. No periprocedural complications occurred. Procedural success was achieved in 96%. Median lesion contact force (25-75 centile) was 4.0(2-6)g. Peak power was set at 50W, median baseline irrigation was at 2ml/min and 6ml/min during ablation. Median number of lesions was 9(4.5-17.5); with total ablation time of 203(95-366) seconds. 60% of the cases were performed without fluoroscopy. Ablation of AVNRT using an irrigated contact force catheter on low irrigation setting is safe and effective. Contact force catheters using low irrigation settings may safely improve success rates in AVNRT with challenging anatomy or ablation of other substrate in close proximity to vital structures.

PO-01-228 CLINICAL SIGNIFICANCE OF STRUCTURAL REMODELING CONCERNING SUBSTRATE CHARACTERISTICS AND ABLATION OUTCOMES IN PATIENTS WITH ATRIAL FIBRILLATION AND MITRAL REGURGITATION

Mitral regurgitation (MR), which causes volume and pressure overload in the left atrium, has been shown to induce left atrial dilation, increasing the risk and likelihood of atrial fibrillation (AF). Catheter ablation of AF may be a potential method to improve the severity of MR in AF patients. To define the clinical significance of structural remodeling of the left atrium on substrate characteristics and ablation outcomes in patients with AF and MR. Patients with AF and moderate to severe MR who underwent catheter ablation from 2011 to 2021 were retrospectively included in the study. Patients' baseline characteristics and electrophysiological features were examined. The patients were classified as group 1 with improved MR (trivial/mild MR after ablation) and group 2 with significant residual MR (MR not improved). The LA was divided into 7 prespecified segments. The scarred segment was defined as more than 50% of the area with bipolar scar after ablation (<0.5 mV). Fifty patients with moderate or severe MR (age 60.2 + 11.4 years, males 21 [65.6%], severe MR 12 [24%]) were included in the study. The degree of MR was improved after ablation in 32 patients after a mean duration of 7.8 + 6.4 months (group 1) and not improved after ablation in 18 patients (group 2). Group 1 patients had a lower CHA2DS2-VASc score (1.7 ± 1.5 vs. 2.7 ± 1.5, P = 0.005) and had a lesser incidence of hypertension (28.1 % vs. 66.7 %, P = 0.007) and diabetes mellitus (3.1% vs. 22.2 %, P = 0.031) as compared to group 2 patients. Electroanatomic three-dimensional (3D) mapping showed that group 1 patients demonstrated less scars in the posterior bottom of the left atrium compared to group 2 patients (12.5 % vs 66.7 %, P < 0.001 ). Group 1 patients also had less AF recurrence compared to group 2 patients (50 % vs 66.7 %, P = 0.264), but time to recurrence of AF was similar between both groups (group 1 17 + 22.2 months vs. group 2 18.6 + 19.8 months, P = 0.847). After multivariate logistic regression analysis, a posterior bottom scar in the left atrium predicted refractory MR (OR 109.302, 95% CI 3.698 - 3230.223, P = 0.007) despite successful AF ablation. Most patients with AF and moderate or severe MR showed improvement of MR to trivial or mild MR within one year after AF ablation. A scar involving the posterior bottom of the left atrium is associated with poor recovery of MR.Tabled 1Univariate and multivariate logistic regression analysis for predicting refractory MR after AF ablationUnivariate AnalysisMultivariate AnalysisOR95% CIP-valueOR95% CIP-valueAge0.9650.913 - 1.0200.208Sex2.3860.732 - 7.7800.149Hypertension5.1111.469 - 17.7800.019.7890.395 - 242.7810.164Diabetes Mellitus1.2080.182 - 8.0020.844Dyslipidemia1.1540.313 - 4.2570.83Chronic Kidney Disease1.8750.241 - 14.5900.548Prior Stroke0.6750.117 - 3.8940.66Cavotricuspid Isthmus ablation0.7280.193 - 2.7500.64CFAE0.8670.189 - 3.9810.854LA linear ablation0.6360.197 - 2.0580.45SVC isolation1.8750.241 - 14.5900.548LA Roof scar0.7310.218 - 2.4440.611LA Anterior Wall scar1.4170.444 - 4.5210.556LA Septal scar1.0290.322 - 3.2900.962LA Posterior scar1.6070.502 - 5.1410.424LA Posterior Bottom scar52.5008.574 - 321.457< 0.0001109.3023.698 - 3230.2230.007LA Lateral Wall scar3.0000.907 - 9.9200.0720.8790.050 - 15.5800.93Baseline Left Atrial Diameter1.0090.935 - 1.0890.825Baseline Left Ventricular Ejection Fraction0.9260.850 - 1.0100.0830.8910.739 - 1.0760.23AF Recurrence4.5001.211 - 16.7190.02524.290.442 - 1335.5110.119*The multivariate regression model was calculated using multiple logistic regression stepwise analysis (included all variables with P<0.1). **LA, left atrium; AF, atrial fibrillation; CFAE, complex fractionated atrial electrogram; SVC, superior vena cava; OR, odds ratio; CI, confidence interval Open table in a new tab

MP-453092-7 THE IMPACT OF ELECTROANATOMICAL MAPPING AND VT SUBSTRATE ABLATION ON PRIMARY AND SECONDARY PREVENTION ICD INDICATION IN PATIENTS WITH REPAIRED TETRALOGY OF FALLOT

MP-453092-7 THE IMPACT OF ELECTROANATOMICAL MAPPING AND VT SUBSTRATE ABLATION ON PRIMARY AND SECONDARY PREVENTION ICD INDICATION IN PATIENTS WITH REPAIRED TETRALOGY OF FALLOT

PO-04-031 SPATIOTEMPORAL STABILITY OF PERSISTENT ATRIAL FIBRILLATION SOURCES: STABLE SOURCE OR DISEASE PROGRESSION?

Catheter ablation (CA) for persistent atrial fibrillation (AF) is challenging and is associated with suboptimal long-term outcomes. A major limitation of standard approaches to treat persistent AF is their predominantly empirical nature. Substrate ablation techniques to improve outcomes have been the subject of many clinical trials. Increasing evidence supports the existence of spatially localized extra pulmonary-vein (PV) sources that maintain persistent AF. Electrographic flow mapping (EGF), CardioInsight and dipole charge density mapping (AcQMap) are three global (atrial) chamber mapping (GACM) based technologies specifically developed to identify AF sources. In this case-series we aimed to assess the spatiotemporal stability of extra-PV sources in patients with persistent AF. We present a series of patients with persistent AF who underwent an initial and at least one redo CA procedure utilizing GACM. The following GACM systems were used: CardioInsight, EGF, and AcQMap, in the following combinations: AcQMap-AcQMap (1 patient), AcQMap-EGF (1 patient), EGF-AcQMap (1 patient), CardioInsight-AcQMap (1 patient), EGF-EGF (3 patients). We reviewed maps and analyzed the location of sources using the 3D mapping system. Spatiotemporal stability was defined as the presence of an AF source of identical location on available maps during the initial and the redo procedure. Seven patients were identified (mean age 62±9 years, 57% male). In 3 patients (43%) localization of AF sources mapped at the repeat procedure corresponded with the localization of sources mapped during the index procedure. In two patient no sources were identified during the second procedure. In the remaining 2 patients the localization of sources was detected at different locations. The figure shows sources with same localization on two different maps acquired with the EGF and the AcQMap system. Spatiotemporal stability of AF sources mapped using GACM systems can be confirmed, however novel sources are found during the repeated procedure suggesting disease progression.

PE-452787-3 INITIAL EXPERIENCE OF PULSED FIELD ABLATION OF ATRIAL FIBRILLATION AND ATRIAL TACHYCARDIA IN ADULT PATIENTS WITH CONGENITAL HEART DISEASE

Prevalence of atrial tachycardias (AT) and atrial fibrillation (AF) is increasing in adult patients with congenital heart disease (CHD) significantly contributing to morbidity. Catheter ablation of AT and AF in the adult CHD population is challenging and recurrence is significant. Pulsed field ablation (PFA) is a new, non-thermal energy source for catheter ablation of AF. Due to its inherent properties of creating effective ablation lesions without permanent affection of non-myocardial tissue, it is attractive for the use in the adult CHD population. To date, its use in the adult CHD population has not been reported. This study describes initial experience of PFA of AT and AF in adult CHD patients. Prospective enrollment of adult CHD patients with a history of recurrent AT/AF, who had prior radiofrequency (RFA)/cryoenergy (Cryo) ablation of AT/AF. A high-density map using a 3D mapping system (EnSite™ Precision; Abbott) in conjunction with a high-density catheter (Advisor™ HD Grid; Abbott) was performed prior and after PFA. PFA was performed using the FARAWAVE™ ablation catheter (Boston Scientific) and applying repeated 2 kV pulses (2.5 s each) to the respective substrate. Procedural success was defined as complete substrate ablation (residual atrial electrograms < 0.05 mV on voltage map). Four adult CHD patients with recurrent AT/AF despite repeated previous RFA/cryoablation were enrolled. 2/4 had interrupted inferior V. cava and a transhepatic access was used to get access to the left atrium. PFA of all pulmonary vein ostia and the left atrial posterior wall was performed in 3 subjects. Additional PFA of a septal low voltage area was achieved in one of these patients. In the fourth patient with Ebstein’s anomaly, PFA of the cavotricuspid isthmus (CTI) and of a conduction gap within the crista terminalis was performed. Complete procedural success was achieved in all patients. Transient, fully reversible spasm of the right coronary artery without ECG changes occurred after PFA within the CTI. No recurrence of AT/AF was observed during follow-up of 5 months. Herein, we report for the first time the use of PFA in adult CHD patients with recurrent AT/AF. PFA turned out to be effective and generally safe. When using it in proximity to the coronary arteries, one must be aware of reversible coronary artery spasm. PFA might be a valuable tool to improve mid- and long-term outcome of AT/AF ablation in the adult CHD population.

Multi-centre, prospective randomized comparison of three different substrate ablation strategies for persistent atrial fibrillation.

The optimal strategy for persistent atrial fibrillation (PerAF) is poorly defined. We conducted a multicentre, randomized, prospective trial to compare the outcomes of different ablation strategies for PerAF. We enrolled 450 patients and randomly assigned them in a 1:1:1 ratio to undergo pulmonary vein isolation and subsequently undergo the following three different ablation strategies: anatomical guided ablation (ANAT group, n = 150), electrogram guided ablation (EGM group, n = 150), and extensive electro-anatomical guided ablation (EXT group, n = 150). The primary endpoint was freedom from atrial fibrillation (AF) lasting longer than 30 s at 12 months after a single ablation procedure. After 12 months of follow-up, 72% (108) of patients in the EXT group were free from AF recurrence, as compared with the 64% (96) in the EGM group (P = 0.116), and 54% (81) in the ANAT group (P = 0.002). The EXT group showed less AF/atrial tachycardia recurrence than the EGM group (60% vs. 50%, P = 0.064) and the ANAT group (60% vs. 37.3%, P < 0.001). The EXT group showed the highest rate of AF termination (66.7%), followed by 56.7% in the EGM group, and 20.7% in the ANAT group. The AF termination signified less AF recurrence at 12 months compared to patients without AF termination (30.1% vs. 42.7%, P = 0.008). Safety endpoints did not differ significantly between the three groups (P = 0.924). Electro-anatomical guided ablation achieved the most favourable outcomes among the three ablation strategies. The AF termination is a reliable ablation endpoint.

GHz bursts in MHz burst (BiBurst) enabling high-speed femtosecond laser ablation of silicon due to prevention of air ionization

For the practical use of femtosecond laser ablation, inputs of higher laser intensity are preferred to attain high-throughput material removal. However, the use of higher laser intensities for increasing ablation rates can have detrimental effects on ablation quality due to excess heat generation and air ionization. This paper employs ablation using BiBurst femtosecond laser pulses, which consist of multiple bursts (2 and 5 bursts) at a repetition rate of 64 MHz, each containing multiple intra-pulses (2–20 pulses) at an ultrafast repetition rate of 4.88 GHz, to overcome these conflicting conditions. Ablation of silicon substrates using the BiBurst mode with 5 burst pulses and 20 intra-pulses successfully prevents air breakdown at packet energies higher than the pulse energy inducing the air ionization by the conventional femtosecond laser pulse irradiation (single-pulse mode). As a result, ablation speed can be enhanced by a factor of 23 without deteriorating the ablation quality compared to that by the single-pulse mode ablation under the conditions where the air ionization is avoided.

Efficacy and Safety of Nonfluoroscopic Approach During Catheter Ablation of Ventricular Tachycardias

Aim To evaluate a possibility of using radiofrequency catheter ablation guided by intracardiac echocardiography (ICE), its efficacy and safety for treatment of ventricular tachycardia (VT) of various etiology.Material and methods Catheter intervention was performed for 20 enrolled patients with symptomatic VT. Ablation procedures were guided by a 3D electroanatomical mapping system and ICE.Results Mean duration of the procedure was 201.2±62.5 min. The procedure was successful (non-inducibility of VT) in 100% of cases. None of the patients had postoperative complications.Conclusion Ablation of VT arrhythmogenic substrate guided by 3D electroanatomical navigational mapping and ICE without X-ray is feasible and safe.

Pattern-Dependent Radio Frequency Heating of Laser-Induced Graphene Flexible Heaters.

Graphene is an excellent choice for heating applications due to its high thermal conductivity and is considered an interesting candidate for application in flexible heaters. The major challenge, though, is the costly and chemical-intensive pathways to produce graphene on a large scale. Laser ablation of polymeric substrates is a relatively recent technique for a facile, single-step, chemical-free fabrication of graphene, referred to as laser-induced graphene (LIG). This work demonstrates the fabrication of patterned LIG-based flexible heaters and their response to radio frequency (RF) electromagnetic waves. Polymeric substrates were scribed with laser patterns in both raster and vector modes and subjected to RF electromagnetic fields to test their heating response. We confirmed different graphene morphologies of the lased patterns through various materials characterization methods. The maximum steady-state temperature observed for the LIG heater was approximately 500 °C. Unprecedented heating rates, as high as 502 °C/s, were observed when LIG heaters were exposed to RF fields at 200 MHz frequency and 4.6 W power. Mechanical and thermal stability tests for the best heater were also performed showing a stable thermal response for 1000 bending cycles and 20 cycles of the heating test for 8.5 h, respectively. Our work suggests that LIG heaters produced in vector mode lasing outperformed those lased in raster mode which can be attributed to the improved graphene quality for RF absorbance.

Cardiac magnetic resonance-aided ventricular tachycardia substrate ablation in corrected tetralogy of Fallot.

Cardiac magnetic resonance-aided ventricular tachycardia substrate ablation in corrected tetralogy of Fallot.

Simultaneous pulmonary vein isolation and ablation of the substrate of biatrial flutter in a patient with a mechanical mitral valve prosthesis: a case report

Catheter radiofrequency ablation of the atrial fibrillation substrate may be difficult in patients after open heart surgery. Difficulties may arise in the presence of a mitral valve prosthesis, atrial arrhythmias of several morphologies (more often left atrial atypical flutter), including incisional ones. These cases require a thorough and scrupulous approach to achieve complete isolation of all available arrhythmia substrates. A distinctive feature of this observation is the successful simultaneous pulmonary vein isolation and two atrial arrhythmias in a patient with a mechanical mitral prosthesis.

Fabrication of metal-based superhydrophilic and underwater superoleophobic surfaces by laser ablation and magnetron sputtering

Fabricating underwater superoleophobic surfaces is an advanced technique for controlling undesirable oil and wax adhesion on engineering structures and household appliances. This article presented a facile method based on the combination of laser ablation of stainless steel substrates followed by magnetron sputtering of a metallic tungsten target to fabricate superhydrophilic and underwater superoleophobic surfaces. The results showed that the laser-ablated stainless steel substrate without coatings exhibited hydrophilicity and underwater oleophobicity. However, its transition to superhydrophilicity and underwater superoleophobicity with a 0° water contact angle and higher than 156° underwater oil contact angles occurred after the deposition of a thin tungsten film followed by annealing at 300 °C. The prepared surface maintained its wetting behavior for more than 4 weeks, even in corrosive aqueous HCl and NaOH solutions. According to the data from SEM and XPS, this distinguished wetting behavior resulted from the presence of the regular microscale texture patterns, abundant hydroxyl content, and low carbon content on the tungsten layer after annealing at 300 °C. Thus, laser ablation combined with magnetron sputtering of tungsten demonstrated effective results in fabricating superhydrophilic and underwater superoleophobic surfaces that are independent of the initial wetting of the substrates.

Ex-vivo histopathologic examination of irrigated radiofrequency ablation utilizing half-normal saline of the human heart.

Radiofrequency ablation (RFA) utilizing half-normal saline (HNS) irrigation is a promising intervention to circumvent commonly encountered limitations during radiofrequency ablation of deep myocardial substrate. Few studies to date have analyzed the morphologic changes in the human myocardium following HNS RFA. Three patients with symptomatic ventricular tachycardia (VT) who underwent RFA with HNS irrigation underwent pathological specimen examination at time of autopsy or following native heart explant at the time of cardiac transplantation. Gross evaluation of the heart was performed fresh and after fixation in 10% formalin. A routine examination was performed with fixation in 10% formalin. Sections of lesioned tissue were paraffin embedded and evaluated using standard hematoxylin and eosin (H&E) staining. Irrigated RF ablation with HNS irrigant produces coagulative necrosis as well as several delayed histopathological changes with a deeper field of effective ablation. Transmurality may not be obtained in the ventricular myocardium with endocardial, epicardial, or sequential unipolar HNS ablation.