Prospective STAR-Guided Ablation in Persistent Atrial Fibrillation Using Sequential Mapping With Multipolar Catheters.

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.

Complete Electroanatomic Imaging of the Diastolic Pathway Is Associated With Improved Freedom From Ventricular Tachycardia Recurrence.

BACKGROUND: The development of multielectrode mapping catheters has expanded the spectrum of mappable ventricular tachycardias (VTs). Full diastolic pathway recording has been associated with a high rate of VT termination during radiofrequency ablation as well as noninducibility at study end. However, the role of diastolic pathway mapping on VT recurrence has yet to be clearly elucidated. We aimed to explore the role of complete diastolic pathway activation mapping on VT recurrence. METHODS: Eighty-five consecutive patients who underwent VT ablation guided by high-density mapping were enrolled. During activation mapping, the presence of electrical activity in all segments of diastole defined the evidence of having had recorded the whole diastolic interval. Patients were categorized as having recorded the full diastolic pathway, partial diastolic pathway, or no diastolic pathway map performed. Recurrences of VT were defined as appropriate implantable cardioverter defibrillator therapies or on the basis of ECG-documented arrhythmia. RESULTS: Eighty-five patients were included. Complete recording of the diastolic pathway was achieved in 36/85 (42.4%) patients. Partial recording of the diastolic pathway of the clinical VT was achieved in 24/85 (28.2%) patients. No recording of the diastolic pathway of the clinical VT was feasible in 25/85 patients (29.4%). At a mean of 12.8 months, freedom from VT recurrence was 67% in the overall cohort. At a mean of 12.8 months, freedom from VT recurrence was 88%, 50%, and 55% in patients who had full diastolic activity recorded, partial diastolic activity recorded, or underwent substrate modification, respectively; the observed differences were statistically significant (P=0.02). CONCLUSIONS: Mapping of the entire diastolic pathway was associated with a higher freedom from VT recurrence as compared with partial diastolic pathway recording and substrate modification. The use of multielectrode mapping catheters in recording diastolic activity may help predict those VTs employing intramural circuits and further optimize ablation strategies.

Precise Signals with a High-Density Grid Mapping Catheter Are Useful for an Entrainment Study.

Complex atrial tachycardias (ATs) after catheter ablation or a MAZE procedure is sometimes difficult to determine the circuits of the tachycardia. A high-density, grid-shapes mapping catheter has been launched, which can be useful for detecting the detail circuits of tachycardias on three-dimensional mapping systems. The signal quality is also important for performing electrophysiological studies (EPSs), such as entrainment mapping, to identify the circuit. This unique mapping catheter has 1 mm electrodes on 2.5 Fr shafts, which improve the signal quality. The high-quality intracardiac electrograms facilitate differentiating small critical potentials, which allows us to perform detailed entrainment mapping in targeted narrow areas. Here, we describe a patient with a perimetral AT with epi-endocardium breakthrough after a MAZE surgery and catheter ablation, which was treated successfully along with detailed entrainment mapping using the HD Grid. This catheter with high-quality signals could be a significant diagnostic tool for a classic EPS as well as for the construction of 3D mapping.

Focal Pulsed Field Ablation for Pulmonary Vein Isolation and Linear Atrial Lesions: A Preclinical Assessment of Safety and Durability.

BACKGROUND: A novel ablation and mapping system can toggle between delivering biphasic pulsed field (PF) and radiofrequency energy from a 9-mm lattice-tip catheter. We assessed the preclinical feasibility and safety of (1) focal PF-based thoracic vein isolation and linear ablation, (2) combined PF and radiofrequency focal ablation, and (3) PF delivered directly atop the esophagus. METHODS: Two cohorts of 6 swine were treated with pulsed fields at low dose (PFLD) and high dose (PFHD) and followed for 4 and 2 weeks, respectively, to isolate 25 thoracic veins and create 5 right atrial (PFLD), 6 mitral (PFHD), and 6 roof lines (radiofrequency+PFHD). Baseline and follow-up voltage mapping, venous potentials, ostial diameters, and phrenic nerve viability were assessed. PFHD and radiofrequency lesions were delivered in 4 and 1 swine from the inferior vena cava onto a forcefully deviated esophagus. All tissues were submitted for histopathology. RESULTS: Hundred percent of thoracic veins (25 of 25) were successfully isolated with 12.4±3.6 applications/vein with mean PF times of <90 seconds/vein. Durable isolation improved from 61.5% PFLD to 100% with PFHD (P=0.04), and all linear lesions were successfully completed without incurring venous stenoses or phrenic injury. PFHD sections had higher transmurality rates than PFLD (98.3% versus 88.1%; P=0.03) despite greater mean thickness (2.5 versus 1.3 mm; P<0.001). PF lesions demonstrated homogenous fibrosis without epicardial fat, nerve, or vessel involvement. In comparison, radiofrequency+PFHD sections revealed similar transmurality but expectedly more necrosis, inflammation, and epicardial fat, nerve, and vessel involvement. Significant ablation-related esophageal necrosis, inflammation, and fibrosis were seen in all radiofrequency sections, as compared with no PF sections. CONCLUSIONS: The lattice-tip catheter can deliver focal PF to durably isolate veins and create linear lesions with excellent transmurality and without complications. The PF lesions did not damage the phrenic nerve, vessels, and the esophagus.

Lattice-Tip Focal Ablation Catheter That Toggles Between Radiofrequency and Pulsed Field Energy to Treat Atrial Fibrillation: A First-in-Human Trial.

BACKGROUND: The tissue selectivity of pulsed field ablation (PFA) provides safety advantages over radiofrequency ablation in treating atrial fibrillation. One-shot PFA catheters have been shown capable of performing pulmonary vein isolation, but not flexible lesion sets such as linear lesions. A novel lattice-tip ablation catheter with a compressible 9-mm nitinol tip is able to deliver either focal radiofrequency ablation or PFA lesions, each in 2 to 5 s. METHODS: In a 3-center, single-arm, first-in-human trial, the 7.5F lattice catheter was used with a custom mapping system to treat paroxysmal or persistent atrial fibrillation. Toggling between energy sources, point-by-point pulmonary vein encirclement was performed using biphasic PFA posteriorly and either temperature-controlled irrigated radiofrequency ablation or PFA anteriorly (RF/PF or PF/PF, respectively). Linear lesions were created using either PFA or radiofrequency ablation. RESULTS: The 76-patient cohort included 55 paroxysmal and 21 persistent atrial fibrillation patients undergoing either RF/PF (40 patients) or PF/PF (36 patients) ablation. The pulmonary vein isolation therapy duration time (transpiring from first to last lesion) was 22.6±8.3 min/patient, with a mean of 50.1 RF/PF lesions/patient. Linear lesions included 14 mitral (4 RF/2 RF+PF/8 PF), 34 left atrium roof (12 RF/22 PF), and 44 cavotricuspid isthmus (36 RF/8 PF) lines, with therapy duration times of 5.1±3.5, 1.8±2.3, and 2.4±2.1 min/patient, respectively. All lesion sets were acutely successful, using 4.7±3.5 minutes of fluoroscopy. There were no device-related complications, including no strokes. Postprocedure esophagogastroduodenoscopy revealed minor mucosal thermal injury in 2 of 36 RF/PF and 0 of 24 PF/PF patients. Postprocedure brain magnetic resonance imaging revealed diffusion-weighted imaging+/fluid-attenuated inversion recovery- and diffusion-weighted imaging+/fluid-attenuated inversion recovery+ asymptomatic lesions in 5 and 3 of 51 patients, respectively. CONCLUSIONS: A novel lattice-tip catheter could safely and rapidly ablate atrial fibrillation using either a combined RF/PF approach (capitalizing on the safety of PFA and the years of experience with radiofrequency energy) or an entirely PF approach. Registration: URL: https://www.clinicaltrials.gov; Unique identifiers: NCT04141007 and NCT04194307.

Catheter ablation of ventricular arrhythmia guided by a high-density grid catheter.

INTRODUCTION: Minimal data exist on the Advisor HD Grid (HDG) catheter and the Precision electroanatomic mapping (EAM) system for ventricular arrhythmia (VA) procedures. Using the HDG catheter, the EAM uses the high-density (HD) wave mapping and best duplicate software to compare the maximum peak-to-peak bipolar voltages within a small zone independent of wavefront direction and catheter orientation. This study aimed to summarize the procedural experience for VAs using the HDG catheter. METHODS: Clinical and procedural characteristics of VA ablation procedures were retrospectively reviewed that used the HDG catheter and the Precision EAM over a 12-month period. RESULTS: A total of 22 patients, 18 with sustained ventricular tachycardia and 4 with premature ventricular contractions were included. Clinically indicated left and/or right ventricular (LV, RV, respectively), and aortic maps were created. LV substrate maps (n = 13) used a median 1700 points (interquartile range [IQR]25%-75% , 1427-2412) out of a median 18 573 (IQR25%-75% , 15 713-41 067) total points collected. RV substrate maps (n = 11) used a median 1435 points (IQR25%-75% , 1114-1871) out of a median 16 005 (IQR25%-75% , 11 063-21 405) total points collected. Total point utilization, used vs collected, was 9%. Mean mapping time was 43 ± 17 minutes (substrate, 34 ± 18 minutes; activation/pace mapping, 9 ± 13 minutes). Acute success was achieved in 56 (86%) and short-term success achieved in 16 patients (73%) at a median follow-up of 145 days (IQR25%-75% , 62-273 days). There were no procedural complications. CONCLUSION: HD wave mapping using the novel HDG catheter integrated with the Precision EAM is safe and feasible in VA procedures in the LV, RV, and aorta. Mapping times are consistent with other multielectrode mapping catheters.

Optimization of the hot balloon ablation strategy using real-time pulmonary vein potential monitoring.

INTRODUCTION: Optimal radiofrequency-generated thermal energy applications have not been established for hot balloon ablation (HBA) systems. We investigated the feasibility of real-time monitoring of pulmonary vein (PV) potentials and optimal time-to-isolation (TTI)-guided application strategies in HBAs. METHODS AND RESULTS: Real-time monitoring of PV potentials was performed using a four-electrode unidirectional catheter in 34 consecutive patients. Acute isolation was achieved when PV potentials disappeared during HBAs and were undetected by high-resolution mapping. The TTI, the difference between TTI and the time to reach target temperature (TTRT), and ablation time after isolation were examined for 177 applications in 136 PVs. Real-time monitoring of PV activity was obtained in 167 out of 177 applications (94.3%) and acute isolation was achieved in 97 out of 177 (54.8%) applications. TTI-TTRT was significantly shorter, and ablation times after isolation were significantly longer in the acute isolation group than in the other groups. TTI-TTRT <4.5 seconds and TTIs <33.5 seconds predicted acute isolation (sensitivity 74.2%, specificity 88.4%; sensitivity 76.3%, specificity 76.7%, respectively). Ablation time after isolation >148.5 seconds (sensitivity 93.6%, specificity 51.7%) and >120.5 seconds (sensitivity 84.0%, specificity 78.6%) predicted acute isolation in superior PVs and inferior PVs, respectively. CONCLUSIONS: Real-time assessment of PV isolation can be achieved during HBAs with single-shot techniques. (TTI-TTRT)s <4.5 seconds and TTIs <33.5 seconds predicted for acute isolation. Ablation time after isolation >148.5 seconds in superior PVs and >120.5 seconds in inferior PVs were effective application durations.

Left atrial voltage mapping with a direction-independent grid catheter: Comparison with a conventional circular mapping catheter.

INTRODUCTION: A recently introduced grid mapping catheter (GMC) is designed for better electrode-tissue contact and can collect bipolar signals both along and across the splines, which may allow more efficient voltage map generation independent of propagation direction. We compared the GMC with a conventional circular mapping catheter (CMC) for left atrial (LA) voltage mapping. METHODS: This study included 20 consecutive patients undergoing repeat ablation for recurrent atrial fibrillation who had demonstrated LA low-voltage areas (LVAs, <0.10 mV). Following pulmonary vein isolation, LA voltage mapping was performed twice, once using the GMC and once using the CMC. RESULTS: Voltage mapping was more efficient using the GMC than the CMC in terms of mapping time (459 [404, 543] vs 602 [496, 814] seconds; P = .014) and the number of mapping points (2446 [2099, 3104] vs 1841 [1494, 2314]; P = .002). The incidence of catheter-induced ectopies was lower (44 [28, 62] vs 114 [74, 188]; P < .0001) using the GMC. The GMC utilizing all bipoles detected LVAs in 85% of patients with LVAs detected by CMC. LVA measurements were significantly smaller on maps generated by the GMC using bipoles along or across the splines than those measured with the CMC (11.1 [4.6, 17.2] or 9.7 [2.5, 16.0] vs 16.4 [6.8, 26.8] cm2 ; P = .008 and P = .001, respectively), and were even smaller when using all bipoles (7.9 [1.1, 13.5] cm2 , P = .0001). CONCLUSION: The GMC allowed a more efficient mapping procedure and enabled more selective identification of LVAs with smaller LVA size.

Identification of repetitive atrial activation patterns in persistent atrial fibrillation by direct contact high-density electrogram mapping.

INTRODUCTION: Recent studies have characterized drivers in persistent atrial fibrillation using automated algorithm detection with panoramic endocardial mapping by means of basket catheters. We aimed to identify repetitive atrial activation patterns (RAAPs) during ongoing atrial fibrillation (AF) based upon automated annotation of unipolar electrograms (EGMs) recorded with a high-density regional endocardial contact mapping catheter. METHODS: In 14 persistent AF patients, high-resolution EGMs were recorded for 30 seconds at sequential PentaRay (Biosense Inc) positions covering the entire biatrial surface. All recordings were reviewed off-line with dedicated software allowing automated annotation of the local activation time of the unipolar fibrillatory EGMs (CARTOFINDER; Biosense Inc). RAAPs were defined as a consistent activation pattern (for ≥3 consecutive beats) of either focal activity with centrifugal spread (RAAPfocal ) or rotational activity across the PentaRay splines spanning the AF cycle length (RAAProtational ). RESULTS: A total of 498 PentaRay recordings were analyzed (35.6 ± 7.6 per patient). The number of PentaRay recordings displaying RAAP was 9.8 ± 3.1 per patient (range = 3-15), of which 2.4 ± 2.4 RAAProtational (range = 0-7), and 7.4 ± 4.4 RAAPfocal (range = 1-13). 77% of RAAPs portrayed focal firing. The median number of repetitions per 30 second recording was 11 (range = 3-225) per recording. RAAPs were observed both in the right atrium (RA) (35%) and left atrium (LA) (65%), with the majority being near the left PVs/appendage (35% of all RAAPs) and the superior vena cava/right appendage (23% of all RAAPs). CONCLUSION: High-resolution, sequential endocardial EGM-based mapping allows identification of RAAPs in persistent AF. In our series, focal firing was the most frequently observed pattern.

Global multielectrode contact-mapping plus ablation with a single catheter in patients with atrial fibrillation: Global AF study.

INTRODUCTION: The critical question for technological advancement of catheter ablation of atrial fibrillation (AF) is whether a creative new concept can combine and even improve the options of single-tip catheters with the simplicity of the use of balloon catheters. Herein are described the results from the first clinical study of a new multielectrode contact-mapping plus ablation array (Globe) offering such a complete solution. METHODS AND RESULTS: The multielectrode Globe array consists of 16 flat ribs with 122 gold-plated electrodes. Each electrode can record electrograms, ablate, pace, and can measure tissue contact and temperature. Single-shot pulmonary vein isolation (PVI) is possible with temperature-guided ablation of up to 24 electrodes simultaneously with automatic, individual power control of every electrode. Sixty patients with symptomatic AF underwent PVI using the Globe. In all sixty patients, acute PVI was achieved in 232 of 234 attempted PVs (99.1%). In 34 patients treated with "single-hot-shot" ablation, PVI was achieved in 136 of 136 PVs (100%). Single-procedure 12-month freedom from AF off antiarrhythmic drugs in the "single-hot-shot" group was 75.5% and freedom from AF/atrial tachycardia 72.3%. In two patients, pericardial tamponade was observed, one after a transseptal puncture, and one during array insertion with an over-advanced sheath. There were no other device-related serious adverse events, including stroke, PV stenosis, esophageal perforation, or phrenic nerve palsy. CONCLUSIONS: In this first clinical series, the Globe catheter was found to be an easy-to-use system for single-shot PVI. The continuously updated multielectrode voltage and activation mapping data indicate future options for mapping and ablation beyond PVI.

Larger and deeper ventricular lesions using a novel expandable spherical monopolar irrigated radiofrequency ablation catheter.

BACKGROUND: Radiofrequency (RF) ablation is an established treatment for ventricular tachycardia (VT). However, the inability of current RF catheters to address deep or large substrate may explain most of the clinical failures. OBJECTIVES: The aim of this study is to assess the efficacy and safety of ablation in the left ventricle (LV) in sheep using a novel 8-Fr deflectable ablation catheter (Sphere-9; Affera, Inc) with a 9-mm expandable spherical monopolar irrigated RF tip vs a standard RF irrigated catheter (Biosense Webster, Diamond Bar, CA). The impact on tissue was assessed on local bipolar electrograms (from nine uniformly distributed mini surface electrodes and an internal central reference electrode), as well as on direct lesion measurement post mortem. METHODS AND RESULTS: Eleven sheep underwent LV endocardial ablation in healthy tissue using the Sphere-9 catheter (n = 6), or a conventional irrigated RF catheter (n = 5). Twenty lesions were created with the Sphere-9 (current limit: 2.7 A; temp. limit: 60°C; irrigation: 30 mL/min; and duration: 60-120 seconds). Local bipolar electrograms at the surface of the catheter disappeared during RF delivery in 17 of 20 (85%) lesions. The mean lesion volume was 1707 ± 771 mm 3 (length: 15.8 ± 3.3 mm; width: 11.6 ± 4.2 mm; and depth: 10.3 ± 2.9 mm). Twenty-five lesions were created with a standard RF irrigated catheter (power control 35 W; irrigation: 30 mL/min; duration: 60 seconds; volume 537 ± 398 mm 3 ; length: 8.2 ± 2.3 mm; width: 5.2 ± 1.8 mm; and depth: 5.5 ± 2.4 mm). The novel spherical RF catheter created significantly larger lesions ( P < .001 for measurements in all dimensions). There were no steam pops with the novel ablation catheter vs one with the conventional catheter. CONCLUSIONS: This novel spherical monopolar irrigated RF catheter creates lesions that are twice as large and deep as a standard irrigated RF catheter.

Evaluation of a new algorithm for tracking activation during atrial fibrillation using multipolar catheters in humans.

BACKGROUND: Conventional mapping techniques during atrial fibrillation (AF) are difficult to apply because of cycle length irregularity. Mapping studies are usually restricted to short durations of AF in limited regions because of the laborious manual annotation of local activation time (LAT). The purpose of this study was to test an automated algorithm to map activation during AF, with comparable accuracy to manual annotation. METHODS: Left atrial (LA) mapping was performed using a 20-pole double loop catheter (AFocusII) in 30-second data segments from 16 patients. The new algorithm (RETRO-Mapping) was designed to detect wavefront propagation between electrodes, and display activating wavefronts on a two-dimensional representation of the catheter. Activation patterns were validated against their bipolar electrograms and with isochronal maps. The mapping protocol was approved by the research ethics committee (13/LO1169 and 14/LO1367). RESULTS: During AF, uniform wavefront activation direction (mean ± SD, degrees) from manually constructed isochronal maps was comparable to RETRO-Propagation Map (RETRO-PM) and RETRO-Automated Direction (RETRO-AD): 1 ± 6.9 for RETRO-PM; and 2 ± 6.6 for RETRO-AD. There was no significant difference in activation direction assigned to 1373 uniform wavefronts during AF when comparing RETRO-PM with RETRO-AD (Bland-Altman mean difference: -0.1 degrees; limits of agreement: -8.0 to 8.3; 95% CI -0.4 to 0.2; (r = 0.01) R2 = < 0.005; P = .77). CONCLUSION: We have developed and validated a new technique to map activation during AF. This technique shows comparable accuracy to that of conventional isochronal mapping with careful manual adjustment of LAT.

Evaluation of a simple technique aiming at optimizing point-by-point isolation of the left pulmonary veins: a randomized study.

AIMS: We sought to evaluate the efficacy and the safety of a simple technique for stabilizing the ablation catheter during anterior pulmonary vein (PV) encirclement in patients ablated for paroxysmal atrial fibrillation. This consisted of bending the ablation catheter in the left atrium, creating a loop that was cautiously advanced together with the long sheath at the ostium and then within the left superior PV. The curve was then progressively released to reach a stable contact with the anterior part of the left PVs. METHODS AND RESULTS: Eighty consecutive patients (age 64 ± 11 years, left atrial diameter 43 ± 8 mm) undergoing 'CLOSE'-guided PV isolation were prospectively randomized into two groups depending on whether the loop technique was used or not. When using the loop technique, the encirclement of the left PVs was shorter [20 min (interquartile range, IQR 17-24) vs. 26 min (IQR 18-33), P < 0.01] with a high rate of first pass isolation [(100%) vs. (97%), P = 0.9] and adenosine proof isolation [(93%) vs. (95%), P = 0.67]. Most specifically, at the anterior part of the left PVs, there were less dislocations [0 (IQR 0-0) vs. 1 (IQR 0-4), P < 0.001], radiofrequency duration was shorter (272 ± 85 s vs. 378 ± 122 s, P < 0.001), force-time integral was higher [524 gs (IQR 427-687) vs. 398 gs (IQR 354-451), P < 0.001], average contact force was higher [20 g (IQR 13-27) vs. 11g (IQR 9-16), P < 0.001], and impedance drop was higher [12 Ω (IQR 9-19) vs. 10 Ω (IQR 7-14), P < 0.001]. CONCLUSION: This study describes a simple technique to facilitate catheter stability at the anterior part of the left PVs, resulting in more efficient left PV encirclement without compromising safety.

Ultra-rapid high-density mapping system with the phase singularity technique is feasible in identifying rotors and focal sources and predicting AF termination.

INTRODUCTION: Phase singularity (PS) mapping provides additional insight into the AF mechanism and is accurate in identifying rotors. The study aimed to evaluate the feasibility of PS mapping in identifying AF rotors using data obtained from an automatic ultra-rapid high-resolution mapping system with a high-density mini-basket catheter. METHODS: Twenty-three pigs underwent rapid right atrial (RA) pacing (RAP 480 bpm) for 5 weeks before the experiment. During AF, RA endocardial automatic continuous mappings with a mini-basket catheter were generated using an automatic ultra-rapid mapping system. Both fractionation mapping and waveform similarity measurements using a PS mapping algorithm were applied on the same recording signals to localize substrates maintaining AF. RESULTS: Seventeen (74%) pigs developed sustained AF after RAP. Three were excluded because of periprocedural ventricular arrhythmia and corrupted digital data. RA fractionation maps were acquired with 6.17 ± 4.29 minutes mean acquisition time, 13768 ± 12698 acquisition points mapped during AF from 581 ± 387 beats. Fractionation mapping identified extensively distributed (66.7%) RA complex fractionated atrial electrogram (CFAE), whereas the nonlinear analysis identified high similarity index (SI > 0.7) parts in limited areas (23.7%). There was an average of 1.67 ± 0.87 SI sites with 0.43 ± 0.76 rotor/focal source/chamber. AF termination occurred in 11/16 (68.75%) AF events in 14 pigs during ablation targeting max CFAE. There was a higher incidence of rotor/focal source at AF termination sites compared with non-AF termination sites (54.5% vs 0%, P = 0.011). CONCLUSIONS: The data obtained from ultra-rapid high-density automatic mapping is feasible and effective in identifying AF rotors/focal sources using PS technique, and those critical substrates were closely related to AF procedural termination.

Locating Atrial Fibrillation Rotor and Focal Sources Using Iterative Navigation of Multipole Diagnostic Catheters.

PURPOSE: Multi-polar diagnostic catheters are used to construct the 3D electro-anatomic mapping of the atrium during atrial fibrillation (AF) ablation procedures; however, it remains unclear how to use the electrograms recorded by these catheters to locate AF-driving sites known as focal and rotor source types. The purpose of this study is to present the first algorithm to iteratively navigate a circular multi-polar catheter to locate AF focal and rotor sources without the need to map the entire atria. METHODS: Starting from an initial location, the algorithm, which was blinded to the location and type of the AF source, iteratively advanced a Lasso catheter based on its electrogram characteristics. The algorithm stopped the catheter when it located of an AF source and identified the type. The efficiency of the algorithm is validated using a set of simulated focal and rotor-driven arrhythmias in fibrotic human 2D and 3D atrial tissue. RESULTS: Our study shows the feasibility of locating AF sources with a success rate of greater than 95.25% within average 7.56 ± 2.28 placements independently of the initial position of the catheter and the source type. CONCLUSIONS: The algorithm could play a critical role in clinical electrophysiology laboratories for mapping patient-specific ablation of AF sources located outside the pulmonary veins and improving the procedure success.

The fourth cryoballoon generation with a shorter tip to facilitate real-time pulmonary vein potential recording: Feasibility and safety results.

INTRODUCTION: Time-to-isolation (TTI) guided ablation protocols have been developed to ensure durable pulmonary vein isolation (PVI) in cryoballoon ablation (CBA). The aim was to determine the feasibility and safety of the fourth generation cryoballoon (CBG4) with a shortened tip. METHODS AND RESULTS: Consecutive patients scheduled for initial atrial fibrillation (AF) ablation were prospectively included. PVI with the 28 mm CBG4 and the latest 20 mm spiral-mapping catheter (SMC) was performed. A total of 302 pulmonary veins (PVs) in 76 patients (64.8 ± 10.4 years, paroxysmal AF 49%) were treated with 617 applications. Left atrium (LA) time, fluoroscopy time, and dose-area product were 65.5 ± 19.2 minutes, 14.6 ± 5.6 minutes, and 1094 (738; 2097) cGy·cm2 , respectively. PVI in cryoballoon technique was achieved in 302 of 302 (100%) PVs. TTI was determined in 256 (84.8%) of PVs. The mean TTI was 45.3 ± 26.4 seconds. Single-shot isolation was achieved in 247 (82%) PVs. In 6 of 302 (2.0%) PV the SMC was changed to a stiff wire to isolate the PV because of instability, and in 17 of 302 (5.6%) of PVs, the 23 mm CB was used to isolate. No radiofrequency touch-up applications were applied. The mean nadir balloon temperature was -44.8°C ± 6.6°C. Balloon dislodgement during positioning occurred in 3 of 617 (0.5%) applications without complications. One PN palsy occurred which resolved until discharge. One patient suffered from the inflammatory syndrome. CONCLUSION: The CBG4 with a shorter distal tip seems to be safe and effective, and allows determining the TTI in 84.8% of PVs. In case of balloon instability, the exchange of the SMC to a stiff wire or, in small PV, the 23 mm cryoballoon facilitate PVI.

A novel octaray multielectrode catheter for high-resolution atrial mapping: Electrogram characterization and utility for mapping ablation gaps.

INTRODUCTION: Multielectrode mapping catheters improve the ability to map within the heterogeneous scar. A novel Octaray catheter with eight spines and 48 electrodes may further improve the speed and resolution of atrial mapping. The aims of this study were to (1) establish the Octaray's baseline mapping performance and electrogram (EGM) characteristics in healthy atria and to (2) determine its utility for identifying gaps in a swine model of atrial ablation lines. METHODS AND RESULTS: The right atria of eight healthy swine were mapped with Octaray and Pentaray catheters (Biosense Webster, Irvine, CA) before and after the creation of ablation lines with intentional gaps. Baseline mapping characteristics including EGM amplitude, duration, number of EGMs, and mapping time were compared. Postablation maps were created and EGM characteristics of continuous lines and gaps were correlated with pathology. Compared with Pentaray, the Octaray collected more EGMs per map (2178 ± 637 vs 1046 ± 238; P < 0.001) at a shorter mapping duration (3.2 ± 0.79 vs 6.9 ± 2.67 minutes; P < 0.001). In healthy atria, the Octaray recorded lower bipolar voltage amplitude (1.96 ± 1.83 mV vs 2.41 ± 1.92 mV; P < 0.001) while ablation gaps were characterized by higher voltage amplitude (1.24 ± 1.12 mV vs 1.04 ± 1.27 mV; P < 0.001). Ablation gaps were similarly identified by both catheters (P = 1.0). The frequency of "false gaps," defined as intact ablation lines with increased voltage amplitude was more common with Pentaray (6 vs 2) and resulted from erroneous annotation of far-field EGMs. CONCLUSION: The Octaray increases the mapping speed and density compared with the Pentaray catheter. It is as sensitive for identifying ablation gaps and more specific for mapping intact ablation lines.