Ablation of atypical atrial flutters using ultra high density-activation sequence mapping.
ABSTRACT: The purpose of this study was to evaluate ultra high density-activation sequence mapping (UHD-ASM) for ablating atypical atrial flutters.For 23 patients with 31 atypical atrial flutters (AAF), we created UHD-ASM.Demographics age?=?65.3?±?8.5 years, male?=?78%, left atrial size?=?4.66?±?0.64 cm, redo ablation 20/23(87%). AAF were left atrial in 30 (97%). For each AAF, 1273?±?697 points were used for UHD-ASM. Time to create and interpret the UHD-ASM was 20?±?11 min. For every AAF, the entire circuit was identified. Thirty (97%) were macroreentry. AAF cycle length was 267?±?49 ms, and the circuit length was 138?±?38 mm (range 35-187). Macroreentry atrial flutters took varied pathways, but each had an area of slow conduction (ASC) averaging 16?±?6 mm (range 6-29) in length. Entrainment was not utilized. We targeted the ASC and ablation terminated AAF directly in 19/31 (61.3%) and altered AAF activation in 7/31 (22.6%), all of which terminated directly with additional mapping/ablation. AAF degenerated to atrial fibrillation in 2/31 (6.5%) with RF and could not be reinduced after ASC ablation. Median time from initial ablation to AAF termination was 64 s. Thus, 28/31 (90.3%) terminated with RF energy and/or could not be reinduced after ASC ablation. At 1 year of follow-up, 77% were free of atrial tachycardia or atrial flutter and 61% were free of all atrial arrhythmias.Using rapidly acquired UHD-ASM, the entire AAF circuit as well as the target ASC could be identified. Most AAF were left atrial macroreentry. Ablation of the ASC or microreentry focuses directly terminated or eliminated AAF in 90.3% without the need for entrainment mapping.
Project description:Success rates for catheter ablation of persistent atrial fibrillation patients are currently low; however, there is a subset of patients for whom electrical isolation of the pulmonary veins alone is a successful treatment strategy. It is difficult to identify these patients because there are a multitude of factors affecting arrhythmia susceptibility and maintenance, and the individual contributions of these factors are difficult to determine clinically. We hypothesised that the combination of pulmonary vein (PV) electrophysiology and atrial body fibrosis determine driver location and effectiveness of pulmonary vein isolation (PVI). We used bilayer biatrial computer models based on patient geometries to investigate the effects of PV properties and atrial fibrosis on arrhythmia inducibility, maintenance mechanisms, and the outcome of PVI. Short PV action potential duration (APD) increased arrhythmia susceptibility, while longer PV APD was found to be protective. Arrhythmia inducibility increased with slower conduction velocity (CV) at the LA/PV junction, but not for cases with homogeneous CV changes or slower CV at the distal PV. Phase singularity (PS) density in the PV region for cases with PV fibrosis was increased. Arrhythmia dynamics depend on both PV properties and fibrosis distribution, varying from meandering rotors to PV reentry (in cases with baseline or long APD), to stable rotors at regions of high fibrosis density. Measurement of fibrosis and PV properties may indicate patient specific susceptibility to AF initiation and maintenance. PV PS density before PVI was higher for cases in which AF terminated or converted to a macroreentry; thus, high PV PS density may indicate likelihood of PVI success.
Project description:Left atrial flutter (LAFL) occurs in patients after atrial fibrillation ablation. Identification of optimal ablation targets to terminate LAFL remains challenging.The purpose of this study was to use patient-specific models to simulate LAFL and predict optimal ablation targets using a novel approach based on flow network theory.Late gadolinium-enhanced cardiac magnetic resonance scans from 10 patients with LAFL were used to construct atrial models incorporating fibrosis by investigators blinded to procedural findings. Rapid pacing was applied in silico to induce LAFL. In each LAFL, we represented reentrant wave propagation as an electric flow network and identified the "minimum cut" (MC), which was the smallest amount of tissue that separated the flow into 2 discontinuous components. In silico ablation was applied at MCs, and targets were compared to those that terminated LAFL during catheter ablation.Patient-specific atrial models were successfully generated from patient scans. LAFL was induced in 7 of 10 models. Ablation of MCs terminated LAFL in 4 models and produced new, slower LAFL morphologies in the other 3. For the latter cases, flow analysis was repeated to identify MCs of emergent LAFLs. Ablation of these MCs terminated emergent LAFLs. The MC-based ablation lesions in simulations were similar in length and location to ablation targets that terminated LAFL during catheter ablation for these 7 patients.Personalized atrial simulations can predict ablation targets for LAFL. These simulations provide a powerful tool for planning ablation procedures and may reduce procedural times and complications.
Project description:BACKGROUND:Localized drivers are proposed mechanisms for persistent atrial fibrillation (AF) from optical mapping of human atria and clinical studies of AF, yet are controversial because drivers fluctuate and ablating them may not terminate AF. We used wavefront field mapping to test the hypothesis that AF drivers, if concurrent, may interact to produce fluctuating areas of control to explain their appearance/disappearance and acute impact of ablation. METHODS:We recruited 54 patients from an international registry in whom persistent AF terminated by targeted ablation. Unipolar AF electrograms were analyzed from 64-pole baskets to reconstruct activation times, map propagation vectors each 20 ms, and create nonproprietary phase maps. RESULTS:Each patient (63.6±8.5 years, 29.6% women) showed 4.0±2.1 spatially anchored rotational or focal sites in AF in 3 patterns. First, a single (type I; n=7) or, second, paired chiral-antichiral (type II; n=5) rotational drivers controlled most of the atrial area. Ablation of 1 to 2 large drivers terminated all cases of types I or II AF. Third, interaction of 3 to 5 drivers (type III; n=42) with changing areas of control. Targeted ablation at driver centers terminated AF and required more ablation in types III versus I (P=0.02 in left atrium). CONCLUSIONS:Wavefront field mapping of persistent AF reveals a pathophysiologic network of a small number of spatially anchored rotational and focal sites, which interact, fluctuate, and control varying areas. Future work should define whether AF drivers that control larger atrial areas are attractive targets for ablation.
Project description:Background:Ethanol infusion has recently been described as a curative strategy for certain peri-mitral flutters by blocking electrical conduction across the mitral isthmus along with the Marshall bundle. The present case showed that a right jugular vein approach, less described, may be a good choice when performing an ethanol infusion in the vein of Marshall (VOM). Case summary:A 45-year-old man was admitted to our unit for dyspnoea associated with an atypical atrial flutter with a cycle length of 320?ms. The left atrial activation map showed a peri-mitral counter-clockwise circuit. The atrial flutter cycle length went up to 345?ms once an endocardial and epicardial point-by point-ablation of the mitral line was completed. At this stage, a new activation map showed that the mitral line was still permeable with an epicardial conduction bridge through the VOM. We decided to use an ethanol infusion for the ablation of the VOM. The coronary sinus could not be thoroughly catheterized due to a winding and angular shape so we decided to try a right jugular vein approach. A total of 9?mL of ethanol was injected into the VOM. A final venogram showed the diffusion of ethanol around the VOM. Sinus rhythm was restored during the last ethanol infusion. A new voltage map confirmed the completion of the mitral line, and we confirmed the bidirectional block. Discussion:The present case showed that a right jugular vein approach may be a good choice when catheterizing and performing an ethanol infusion in the VOM.
Project description:BACKGROUND:The most efficient first-time invasive treatment, for achieving sinus rhythm, in symptomatic paroxysmal atrial fibrillation has not been established. We aimed to compare percutaneous catheter and video-assisted thoracoscopic pulmonary vein radiofrequency ablation in patients referred for first-time invasive treatment due to symptomatic paroxysmal atrial fibrillation. The primary outcome of interest was the prevalence of atrial fibrillation with and without anti-arrhythmic drugs at 12 months. METHODS:Ninety patients were planned to be randomised to either video-assisted thoracoscopic radiofrequency pulmonary vein ablation with concomitant left atrial appendage excision or percutaneous catheter pulmonary vein ablation. Episodes of atrial fibrillation were defined as more than 30 s of atrial fibrillation observed on Holter monitoring/telemetry or clinical episodes documented by ECG. RESULTS:The study was terminated prematurely due to a lack of eligible patients. Only 21 patients were randomised and treated according to the study protocol. Thoracoscopic pulmonary vein ablation was performed in 10 patients, and 11 patients were treated with catheter ablation. The absence of atrial fibrillation without the use of anti-arrhythmic drugs throughout the follow-up was observed in 70% of patients following thoracoscopic pulmonary vein ablation and 18% after catheter ablation (p?<?0.03). CONCLUSION:Thoracoscopic pulmonary vein ablation may be superior to catheter ablation for first-time invasive treatment of symptomatic paroxysmal atrial fibrillation with regard to obtaining sinus rhythm off anti-arrhythmic drugs 12 months postoperative. TRIAL REGISTRATION:ClinicalTrials.gov Identifier: NCT01336075 . Registered April 15th, 2011.
Project description:BACKGROUND:A novel stochastic trajectory analysis of ranked signals (STAR) mapping approach to guide atrial fibrillation (AF) ablation using basket catheters recently showed high rates of AF termination and subsequent freedom from AF. METHODS:This study aimed to determine whether STAR mapping using sequential recordings from conventional pulmonary vein mapping catheters could achieve similar results. Patients with persistent AF<2 years were included. Following pulmonary vein isolation AF drivers (AFDs) were identified on sequential STAR maps created with PentaRay, IntellaMap Orion, or Advisor HD Grid catheters. Patients had a minimum of 10 multipolar recordings of 30 seconds each. These were processed in real-time and AFDs were targeted with ablation. An ablation response was defined as AF termination or cycle length slowing ?30 ms. RESULTS:Thirty patients were included (62.4±7.8 years old, AF duration 14.1±4.3 months) of which 3 had AF terminated on pulmonary vein isolation, leaving 27 patients that underwent STAR-guided AFD ablation. Eighty-three potential AFDs were identified (3.1±1.1 per patient) of which 70 were targeted with ablation (2.6±1.2 per patient). An ablation response was seen at 54 AFDs (77.1% of AFDs; 21 AF termination and 33 cycle length slowing) and occurred in all 27 patients. No complications occurred. At 17.3±10.1 months, 22 out of 27 (81.5%) patients undergoing STAR-guided ablation were free from AF/atrial tachycardia off antiarrhythmic drugs. CONCLUSIONS:STAR-guided AFD ablation through sequential mapping with a multipolar catheter effectively achieved an ablation response in all patients. AF terminated in a majority of patients, with a high freedom from AF/atrial tachycardia off antiarrhythmic drugs at long-term follow-up. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02950844.
Project description:Electrogram-based catheter ablation, targeting complex fractionated atrial electrograms (CFAEs), is empirically known to be effective in halting persistent/permanent atrial fibrillation (AF). However, the mechanisms underlying CFAEs and electrogram-based ablation remain unclear.Because atrial fibrosis is associated with persistent/permanent AF, we hypothesized that electrotonic interactions between atrial myocytes and fibroblasts play an important role in CFAE genesis and electrogram-based catheter ablation.We used a human atrial tissue model in heart failure and simulated propagation and spiral wave reentry with and without regionally proliferated fibroblasts. Coupling of fibroblasts to atrial myocytes resulted in shorter action potential duration, slower conduction velocity, and lower excitability. Consequently, heterogeneous fibroblast proliferation in the myocardial sheet resulted in frequent spiral wave breakups, and the bipolar electrograms recorded at the fibroblast proliferation area exhibited CFAEs. The simulations demonstrated that ablation targeting such fibroblast-derived CFAEs terminated AF, resulting from the ablation site transiently pinning the spiral wave and then pushing it out of the fibroblast proliferation area. CFAEs could not be attributed to collagen accumulation alone.Fibroblast proliferation in atria might be responsible for the genesis of CFAEs during persistent/permanent AF. Our findings could contribute to better understanding of the mechanisms underlying CFAE-targeted AF ablation.
Project description:The mechanisms for atrial fibrillation (AF) are unclear in part because diverse mapping techniques yield diverse maps, ranging from stable organized sources to highly disordered waves. We hypothesized that AF mechanisms may be clarified if mapping techniques were compared in the same patients, and referenced to a clinical endpoint. We compared two independent AF mapping techniques in patients in whom ablation terminated persistent AF before pulmonary vein isolation (PVI).We identified 12 patients with persistent AF (61.2 ± 10.8 years, four female) in whom mapping with 64 pole baskets and technique 1 (activation/phase mapping, FIRM) identified rotational activation patterns during at least 50% of the 4-second mapping interval and targeted ablation at these rotational sites terminated AF to sinus rhythm (n = 10) or atrial tachycardia. We analyzed the unipolar electrograms of these patients to determine phase maps of activation by an independent technique 2 (Kuklik, Schotten et al., IEEE Trans Biomed Eng 2015). Compared to technique 1, technique 2 revealed a source in 12 of 12 (100%) cases with spatial concordance in all cases (P <0.05) and similar rotational characteristics.At sites where ablation terminated persistent AF, two independent mapping techniques identified stable rotational activation for multiple cycles that drove peripheral disorder. Future comparative studies referenced to a clinical endpoint may help reconcile if discrepancies between AF mapping studies reports represent techniques, patient populations or models of AF, and improve mapping to better guide ablation.
Project description:INTRODUCTION:Targeting repeating-pattern atrial fibrillation (AF) sources (reentry or focal drivers) can help in patient-specific ablation therapy for AF; however, the development of reliable and accurate tools for locating such sources remains a major challenge. We describe iterative catheter navigation (ICAN) algorithm to locate AF drivers using a conventional circular Lasso catheter. METHODS AND RESULTS:At each step, the algorithm analyzes 10 bipolar electrograms recoded at a given catheter location and the history of previous catheter movements to determine if the source is inside the catheter loop. If not, it calculates new coordinates and selects a new position for the catheter. The process continues until a source is located. The algorithm was evaluated in a computer model of atrial tissue with various degrees of fibrosis under a broad range of arrhythmia scenarios. The latter included slow and fast reentry, macroreentry, figure-of-eight reentry, and fibrillatory conduction. Depending on the initial distance of the catheter from the source and scenario, it took about 3 to 16 steps to localize an AF source. In 94% of cases, the identified location was within 4?mm from the source, independently of the initial position of the catheter. The algorithm worked equally well in the presence of patchy fibrosis, low-voltage areas, fragmented electrograms, and dominant-frequency gradients. CONCLUSIONS:AF repeating-pattern sources can be localized using circular catheters without the need to map the entire tissue. The proposed algorithm has the potential to become a useful tool for patient-specific ablation of AF sources located outside the pulmonary veins.
Project description:Both primary auditory cortex (A1) and anterior auditory field (AAF) are core regions of auditory cortex of many mammalians. While the function of A1 has been well documented, the role of AAF in sound related behavioral remain largely unclear. Here in adult rats, sound cued fear conditioning paradigm, surgical ablation, and chemogenetic manipulations were used to examine the role of AAF in fear related sound context recognition. Precise surgical ablation of AAF cannot block sound cued freezing behavior but the fear conditioning became non-selective to acoustic cue. Reversible inhibition of AAF using chemogenetic activation at either training or testing phase can both lead to strong yet non-selective sound cued freezing behavior. These simple yet clear results suggested that in sound cued fear conditioning, sound cue and detailed content in the cue (e.g., frequency) are processed through distinct neural circuits and AAF is a critical part in the cortex dependent pathway. In addition, AAF is needed and playing a gating role for precise recognition of sound content in fear conditioning task through inhibiting fear to harmless cues.