ORCID Profile
0000-0001-9144-9679
Current Organisations
University of Otago Christchurch
,
Canterbury District Health Board
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Publisher: Elsevier BV
Date: 2015
Publisher: Elsevier BV
Date: 2014
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 12-2014
DOI: 10.1161/CIRCEP.113.001219
Abstract: The optimal contact force (CF) for ventricular mapping and ablation remains unvalidated. We assessed CF in different endocardial and epicardial regions during ventricular tachycardia substrate mapping using a CF-sensing catheter (Smartouch Biosense-Webster) and compared the transseptal versus retroaortic approach. In total, 8979 mapping points with CF, and force vector orientation (VO) were recorded in 21 patients, comprising 13 epicardial, 12 left ventricular (6 transseptal and 6 retroaortic approach), and 12 right ventricular endocardial maps. VO was defined as adequate when the vector was directed toward the myocardium. During epicardial mapping, 46% of the points showed an adequate VO and a median CF of 8 (4–13) g, however, with significant differences among the 8 regions. When VO was inadequate, median CF was higher at 16 (10–24) g ( P .0001). During left ventricular and right ventricular endocardial mapping, 94% of VO were adequate. Median CF of adequate VO was higher in the left ventricular and right ventricular endocardium than in the epicardium (15 [8–25] and 13 [7–22] g versus 8 [4–13] g, respectively both P .001). Global median left ventricular CF with transseptal approach was not statistically different from retroaortic approach, but CF in the apicoinferior and apicoseptal regions was higher with transseptal approach ( P .001). Ventricular mapping demonstrates important regional variations in CF, but in general, CF is higher endocardially than epicardially where poor catheter orientation is associated with higher CF. A transseptal approach may lead to improved contact particularly in the apicoseptal and inferior regions.
Publisher: Radcliffe Group Ltd
Date: 2013
Abstract: The authors describe a novel three-dimensional, 252-lead electrocardiography (ECG) and computed tomography (CT)-based non-invasive cardiac imaging and mapping modality. This technique images potentials, electrograms and activation sequences (isochrones) on the epicardial surface of the heart. This tool has been investigated in the normal cardiac electrophysiology and various tachyarrhythmic, conduction and anomalous depo-repolarisation disorders. The clinical application of this system includes a wide range of electrical disorders like atrial arrhythmias (premature atrial beat, atrial tachycardia, atrial fibrillation), ventricular arrhythmias (premature ventricular beat, ventricular tachycardia) and ventricular pre-excitation (Wolff-Parkinson-White syndrome). In addition, the system has been used in exploring abnormalities of the His-Purkinje conduction like the bundle branch block and intraventricular conduction disturbance and thereby useful in electrically treating the associated heart failure (cardiac resynchronisation). It has a potential role in furthering our understanding of abnormalities of ventricular action potential (depolarisation [Brugada syndrome and repolarisation], long QT and early repolarisation syndromes) and in evaluating the impact of drugs on His-Purkinje conduction and cardiac action potential.
Publisher: Elsevier BV
Date: 02-2022
Publisher: Elsevier
Date: 2017
Publisher: Elsevier BV
Date: 11-2013
DOI: 10.1016/J.HRTHM.2013.08.031
Abstract: Local abnormal ventricular activities (LAVA) in patients with scar-related ventricular tachycardia (VT) may appear at any time during or after the far-field electrogram. Although they may be separated from the far-field signal by an isoelectric line and extend beyond the end of surface QRS, they may also appear fused or buried within the QRS. The purpose of this study was to characterize LAVA in postinfarction VT patients with respect to their anatomic locations. Thirty-one patients with postinfarction VT underwent mapping/ablation during sinus rhythm with a three-dimensional electroanatomic mapping system. From a total of 18,270 electrograms reviewed in all study subjects, 1104 LAVA (endocardium 839, epicardium 265) were identified and analyzed. The interval from onset of QRS complex to ventricular electrogram (EGM onset) on the endocardium was significantly shorter than the epicardium (P < .001). EGM onset was shortest in the septal endocardium and longest in the inferior and lateral epicardium. There was a significant positive correlation between EGM onset and LAVA lateness as estimated by the interval from surface QRS onset to LAVA (r = 0.52, P < .001). LAVA were more frequently detected after the QRS complex in the epicardium (241/265 [91%]) than in the endocardium (551/839 [66%], P < .001). Only 43% of endocardial septal LAVA were detected after the QRS complex. Lateness of LAVA is affected to a large extent by their locations. The chance of detecting late LAVA increases when electrogram onset is later. Substrate-based approach targeting delayed signals relative to the QRS complex may miss critical the arrhythmogenic substrate, particularly in the septum and other early-to-activate regions.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 12-08-2014
DOI: 10.1161/CIRCULATIONAHA.113.005421
Abstract: Specific noninvasive signal processing was applied to identify drivers in distinct categories of persistent atrial fibrillation (AF). In 103 consecutive patients with persistent AF, accurate biatrial geometry relative to an array of 252 body surface electrodes was obtained from a noncontrast computed tomography scan. The reconstructed unipolar AF electrograms acquired at bedside from multiple windows (duration, 9±1 s) were signal processed to identify the drivers (focal or reentrant activity) and their cumulative density map. The driver domains were catheter ablated by using AF termination as the procedural end point in comparison with the stepwise-ablation control group. The maps showed incessantly changing beat-to-beat wave fronts and varying spatiotemporal behavior of driver activities. Reentries were not sustained (median, 2.6 rotations lasting 449±89 ms), meandered substantially but recurred repetitively in the same region. In total, 4720 drivers were identified in 103 patients: 3802 (80.5%) reentries and 918 (19.5%) focal breakthroughs most of them colocalized. Of these, 69% reentries and 71% foci were in the left atrium. Driver ablation alone terminated 75% and 15% of persistent and long-lasting AF, respectively. The number of targeted driver regions increased with the duration of continuous AF: 2 in patients presenting in sinus rhythm, 3 in AF lasting 1 to 3 months, 4 in AF lasting 4 to 6 months, and 6 in AF lasting longer. The termination rate sharply declined after 6 months. The mean radiofrequency delivery to AF termination was 28±17 minutes versus 65±33 minutes in the control group ( P .0001). At 12 months, 85% patients with AF termination were free from AF, similar to the control population (87%,) P =not significant. Persistent AF in early months is maintained predominantly by drivers clustered in a few regions, most of them being unstable reentries.
Publisher: Elsevier BV
Date: 11-2015
Publisher: Elsevier BV
Date: 2015
Publisher: Wiley
Date: 05-12-2015
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 04-2013
DOI: 10.1161/CIRCEP.112.000191
Abstract: A majority of patients undergoing ablation of ventricular tachycardia have implanted devices precluding substrate imaging with delayed-enhancement MRI. Contrast-enhanced multidetector computed tomography (MDCT) can depict myocardial wall thickness with submillimetric resolution. We evaluated the relationship between regional myocardial wall thinning (WT) imaged by MDCT and arrhythmogenic substrate in postinfarction ventricular tachycardia. We studied 13 consecutive postinfarction patients undergoing MDCT before ablation. MDCT data were integrated with high-density 3-dimensional electroanatomic maps acquired during sinus rhythm (endocardium, 509±291 points/map epicardium, 716±323 points/map). Low-voltage areas ( .5 mV) and local abnormal ventricular activities (LAVA) during sinus rhythm were assessed with regard to the WT. A significant correlation was found between the areas of WT mm and endocardial low voltage (correlation- R =0.82 P =0.001), but no such correlation was found in the epicardium. The WT mm area was smaller than the endocardial low-voltage area (54 cm 2 [Q1–Q3, 46–92] versus 71 cm 2 [Q1–Q3, 59–124] P =0.001). Among a total of 13 060 electrograms reviewed in the whole study population, 538 LAVA were detected and analyzed. LAVA were located within the WT mm (469/538 [87%]) or at its border (100% within 23 mm). Very late LAVA ( ms after QRS complex) were almost exclusively detected within the thinnest area (93% in the WT mm). Regional myocardial WT correlates to low-voltage regions and distribution of LAVA critical for the generation and maintenance of postinfarction ventricular tachycardia. The integration of MDCT WT with 3-dimensional electroanatomic maps can help focus mapping and ablation on the culprit regions, even when MRI is precluded by the presence of implanted devices.
Publisher: Oxford University Press (OUP)
Date: 06-2017
Publisher: Elsevier BV
Date: 02-2010
Publisher: Elsevier BV
Date: 06-2013
Publisher: Elsevier BV
Date: 06-2014
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 15-08-2014
Abstract: Myocardial fibrofatty infiltration is a milieu for ventricular tachycardia ( VT ) in arrhythmogenic right ventricular cardiomyopathy ( ARVC ) and can be depicted as myocardial hypodensity on contrast‐enhanced multidetector computed tomography ( MDCT ) with high spatial and temporal resolution. This study aimed to assess the relationship between MDCT ‐imaged myocardial fat and VT substrate in ARVC . We studied 16 patients with ARVC who underwent ablation and preprocedural MDCT . High‐resolution imaging data were processed and registered to high‐density endocardial and epicardial maps in sinus rhythm on 3‐dimensional electroanatomic mapping (3D‐ EAM ) (626±335 and 575±279 points/map, respectively). Analysis of the locations of low‐voltage and fat segmentation included the following endocardial and epicardial regions: apex, mid (anterior, lateral, inferior), and basal (anterior, lateral, inferior). The location of local abnormal ventricular activities ( LAVA ) was compared with fat distribution. RV myocardial fat was successfully segmented and integrated with 3D‐ EAM in all patients. The κ agreement test demonstrated a good concordance between the epicardial low voltage and fat (κ=0.69, 95% CI 0.54 to 0.84), but fair concordance with the endocardium (κ=0.41, 95% CI 0.27 to 0.56). The majority of LAVA (520/653 [80%]) were located within the RV fat segmentation, of which 90% were not farther than 20 mm from its border. Registration of MDCT allowed direct visualization of the coronary arteries, thus avoiding coronary damage during epicardial radiofrequency delivery. The integration of MDCT ‐imaged myocardial fat with 3D‐ EAM provides valuable information on the extent and localization of VT substrate and demonstrates ablation targets clustering in its border region.
Publisher: Public Library of Science (PLoS)
Date: 03-05-2019
Publisher: Elsevier BV
Date: 2014
Publisher: Oxford University Press (OUP)
Date: 18-06-2014
Abstract: Pulmonary vein isolation (PVI) is the mainstay of interventional treatment of paroxysmal atrial fibrillation (PAF). We report on the feasibility and efficacy of a novel, open-irrigated mapping and radiofrequency (RF) ablation catheter. Thirty-nine consecutive patients (pts age 60 ± 10 years, 8 females) suffering from drug-refractory PAF referred for PVI were included in this prospective study. Pulmonary vein isolation was performed with the use of a novel 10-pole circular, open-irrigated mapping and ablation catheter (nMARQ, Biosense Webster). Outcome parameters were the acute success rate in establishing complete PVI and the rate of sustained sinus rhythm (SR) during follow-up (FU). Ten patients underwent a repeat procedure for recurrent AF. Ninety-eight percent of the PVs could be acutely isolated using solely the nMARQ catheter by applying a mean total of 10.0 ± 4.6 min of RF energy. The mean total procedure duration was 86 ± 29 min, and the mean fluoroscopy time was 22.2 ± 6.5 min, respectively. Transient reconnection provoked by adenosine was observed in 10 of 24 patients, most frequently in the right superior PV. Cardiac t onade related to transseptal puncture occurred in one patient. Reconnected PVs could be identified as a source of recurrent AF in 9 of 10 patients undergoing a repeat procedure. Single and multiple procedure success rates during a mean FU of 140 ± 75 days were 66 and 77%, respectively. Irrigated multi-electrode RF ablation is fast and effective, providing a high rate of isolated PVs without the need of touch-up lesions. Success rates were comparable with other techniques with a low complication rate. Recurrences of AF were mainly due to recovered pulmonary vein/left atrium conduction.
Publisher: Elsevier BV
Date: 12-2012
DOI: 10.1016/J.HRTHM.2012.08.003
Abstract: Inferolateral early repolarization (ER) and Brugada syndrome manifest with J waves. Isoproterenol suppresses recurrent ventricular arrhythmias while reducing J waves in both disorders. To characterize the effect of isoproterenol on J waves. We analyzed the impact of isoproterenol on J waves in 20 patients with Brugada-type electrocardiogram (Br group) and 38 patients with ER (ER group). In the ER group, J waves were present in inferior leads in 32 patients (84%) and in lateral leads in 23 patients (61%). Isoproterenol increased the heart rate by 75 beats/min in the ER group and by 71 beats/min in the Br group (P = .20). The incidences of persistent (≤ 0.05-mV decrease), decreased, and normalized J waves (residual J wave ≤ 0.05 mV) were 20%, 80%, and 0% for Br group patients and 29%, 8%, and 63% for ER group patients, respectively (P <.001). Within the ER group, inferior J waves persisted in 34% of the cases, decreased in 9%, and normalized in 56% whereas lateral J waves always normalized (P <.001). Baseline QRS width was broader in ER group patients with persistent J waves (90 ms vs 80 ms P = .003) and was unchanged with isoproterenol (90 ms P = .19), whereas it decreased in the remaining patients (75 ms P <.001). J-wave syndromes have distinct regional sensitivity to beta-adrenergic stimulation. J waves may persist in a subset of patients with right precordial and inferior J waves but never in lateral location. This heterogeneous response to isoproterenol may indicate distinctive mechanisms for Brugada and ER patterns, including depolarization abnormalities or ion channel sensitivity.
Publisher: Elsevier BV
Date: 2014
Publisher: Elsevier BV
Date: 03-2017
DOI: 10.1016/J.JACC.2017.01.014
Abstract: The underlying mechanisms sustaining human persistent atrial fibrillation (PsAF) is poorly understood. This study sought to investigate the complexity and distribution of AF drivers in PsAF of varying durations. Of 135 consecutive patients with PsAF, 105 patients referred for de novo ablation of PsAF were prospectively recruited. Patients were ided into 3 groups according to AF duration: PsAF presenting in sinus rhythm (AF induced), PsAF 12 months. Patients wore a 252-electrode vest for body surface mapping. Localized drivers (re-entrant or focal) were identified using phase-mapping algorithms. In this patient cohort, the most prominent re-entrant driver regions included the pulmonary vein (PV) regions and inferoposterior left atrial wall. Focal drivers were observed in 1 or both PV regions in 75% of patients. Comparing between the 3 groups, with longer AF duration AF complexity increased, reflected by increased number of re-entrant rotations (p < 0.05), number of re-entrant rotations and focal events (p < 0.05), and number of regions harboring re-entrant (p < 0.01) and focal (p < 0.05) drivers. With increased AF duration, a higher proportion of patients had multiple extra-PV driver regions, specifically in the inferoposterior left atrium (p < 0.01), superior right atrium (p < 0.05), and inferior right atrium (p < 0.05). Procedural AF termination was achieved in 70% of patients, but decreased with longer AF duration. The complexity of AF drivers increases with prolonged AF duration. Re-entrant and focal drivers are predominantly located in the PV antral and adjacent regions. However, with longer AF duration, multiple drivers are distributed at extra-PV sites. AF termination rate declines as patients progress to longstanding PsAF, underscoring the importance of early intervention.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 08-2014
DOI: 10.1161/CIRCEP.113.001224
Abstract: Although the Task Force Criteria for arrhythmogenic right ventricular cardiomyopathy (ARVC) have recently been updated, the diagnosis remains challenging in the early stages. The aim of this study was to evaluate the diagnostic value of β-adrenergic stimulation in ARVC. We evaluated 412 consecutive patients (213 men, age 41.5±16 years) referred for premature ventricular contractions evaluation or suspected ARVC. Isoproterenol testing was performed with continuous infusion of isoproterenol (45 μg/min) for 3 minutes. It was considered positive if there were either (1) polymorphic premature ventricular contractions with ≥1 couplet or (2) sustained or nonsustained ventricular tachycardia with left bundle branch block excluding right ventricular outflow tract ventricular tachycardia. ARVC was diagnosed in 35 patients at initial evaluation (23 men, aged 42±15 years). Isoproterenol testing was positive in 32 of 35 (91.4%) patients with ARVC and in 42 of 377 (11.1%) patients without ARVC ( P .0001). Sensitivity, specificity, positive, and negative predictive values of isoproterenol testing to diagnose ARVC were 91.4%, 88.9%, 43.2%, and 99.1%, respectively. During a mean follow-up period of 5.6±4.4 years, 6 additional patients met diagnostic criteria for ARVC. Importantly, initial isoproterenol testing was positive in 6 of 6 (100%) of these patients. Survival free from ARVC diagnosis was significantly lower in the positive isoproterenol group than in the negative isoproterenol group ( P .0001, exact log-rank test). Ventricular arrhythmogenicity during isoproterenol testing is highly sensitive (sensitivity, 91.4%) for the diagnosis of ARVC, particularly in its early stages.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 06-2014
DOI: 10.1161/CIRCEP.113.001264
Abstract: Rapid pulmonary vein (PV) activity has been shown to maintain paroxysmal atrial fibrillation (AF). We evaluated in persistent AF the cycle length (CL) gradient between PVs and the left atrium (LA) in an attempt to identify the subset of patients where PVs play an important role. Ninety-seven consecutive patients undergoing first ablation for persistent AF were studied. For each PV, the CL of the fastest activation was assessed over 1 minute (PV fast ) using Lasso recordings. The PV to LA CL gradient was quantified by the ratio of PV fast to LA appendage (LAA) AF CL. Stepwise ablation terminated AF in 73 patients (75%). In the AF termination group, the PV fast CL was much shorter than the LAA CL resulting in lower PV fast /LAA ratios compared with the nontermination group (71±10% versus 92±7% P .001). Within the termination group, PV fast /LAA ratios were notably lower if AF terminated after PV isolation or limited adjunctive substrate ablation compared with patients who required moderate or extensive ablation (63±6% versus 75±8% P .001). PV fast /LAA ratio % predicted AF termination after PV isolation or limited substrate ablation with 74% positive predictive value and 95% negative predictive value. After a mean follow-up of 29±17 months, freedom from arrhythmia recurrence off-antiarrhythmic drugs was achieved in most patients with PV fast /LAA ratios % as opposed to the remaining population (80% versus 43% P .001). The PV to LA CL gradient may identify the subset of patients in whom persistent AF is likely to terminate after PV isolation or limited substrate ablation and better long-term outcomes are achieved.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 06-2013
DOI: 10.1161/CIRCEP.113.000182
Abstract: Atrial tachycardias (AT) during or after ablation of atrial fibrillation frequently pose a diagnostic challenge. We hypothesized that both the patterns and the timing of coronary sinus (CS) activation could facilitate AT mapping. A total of 140 consecutive postpersistent atrial fibrillation ablation patients with sustained AT were investigated by conventional mapping. CS activation pattern was defined as chevron or reverse chevron when the activations recorded on both the proximal and the distal CS dipoles were latest or earliest, respectively. The local activation of mid-CS was timed with reference to P peak –P peak (P–P) interval in lead V1. A ratio, mid-CS activation time to AT cycle length, was computed. Of 223 diagnosed ATs, 124 were macroreentrant (56%) and 99 were centrifugal (44%). When CS activation was chevron/reverse chevron (n=44 20%), macroreentries were mostly roof dependent. With reference to P–P interval, mid-CS activation timing showed specific consistency for peritricuspid and perimitral AT. Proximal to distal CS activation pattern and mid-CS activation at 50% to 70% of the P–P interval (n=30 13%) diagnosed peritricuspid AT with 81% sensitivity and 89% specificity. Distal to proximal CS activation and mid-CS activation at 10% to 40% of the P–P interval (n=44 20%) diagnosed perimitral AT with 88% sensitivity and 75% specificity. The analysis of the patterns and timing of CS activation provides a rapid stratification of most likely macroreentrant ATs and points toward the likely origin of centrifugal ATs. It can be included in a stepwise diagnostic approach to rapidly select the most critical mapping maneuvers.
Publisher: Future Medicine Ltd
Date: 11-2015
DOI: 10.2217/FCA.15.62
Abstract: While pulmonary vein isolation for paroxysmal atrial fibrillation (AF) is highly effective, catheter ablation for persistent AF remains a challenge with varying clinical success reported. Several ablation techniques have been proposed to target persistent AF, with the additional ablation of complex fractionated electrograms and linear lesions shown to provide incremental success to pulmonary vein isolation alone. Recently, several studies have suggested the presence of localized drivers (re-entrant or focal) in AF. By targeting these drivers, clinical outcomes may be maintained while minimizing the extent of ablation. This article will focus on the conventional stepwise ablation approach for persistent AF versus driver-guided ablation with the use of newer mapping technologies.
Publisher: Elsevier BV
Date: 2018
DOI: 10.1016/J.JACEP.2017.07.018
Abstract: The purpose of this study was to describe and identify useful electrocardiographic characteristics to help identify the mechanism of atrial tachycardia (AT) occurring after persistent atrial fibrillation (PsAF) ablation. Electrocardiographic analysis to help identify the mechanism of AT after PsAF ablation is much limited by the fact that remodeling and ablation alter the normal activation pattern. All consecutive patients who underwent mapping and ablation of AT after PsAF ablation were included. Surface P waves were analyzed during higher (>2:1) grades of atrioventricular block. One hundred ninety-six ATs with visible P waves were identified in 127 patients (macro-re-entry in 57%, centrifugal AT in 43%). One-third displayed low-voltage P waves (≤0.1 mV). An isoelectric line >80 ms was more common in centrifugal compared with macro-re-entrant AT (47% vs. 24% p < 0.001), but its positive predictive value was limited (60%). A minority of peritricuspid ATs displayed the classic saw-tooth pattern (27% [n = 22]). However, the "precordial transition" (a gradual transition from an upright component in lead V Only few unique electrocardiographic characteristics help identify the mechanism of AT after PsAF ablation. Knowledge of these characteristics may aid in planning and performing ablation.
Publisher: Elsevier BV
Date: 04-2014
DOI: 10.1016/J.JACC.2013.10.087
Abstract: We evaluated the feasibility and safety of epicardial substrate elimination with endocardial radiofrequency (RF) delivery in patients with scar-related ventricular tachycardia (VT). Epicardial RF delivery is limited by fat or associated with bleeding, extra-cardiac damages, coronary vessels and phrenic nerve injury. Alternative ablation approaches might be desirable. Forty-six patients (18 ischemic cardiomyopathy [ICM], 13 nonischemic dilated cardiomyopathy [NICM], 15 arrhythmogenic right ventricular cardiomyopathy [ARVC]) with sustained VT underwent combined endo- and epicardial mapping. All patients received endocardial ablation targeting local abnormal ventricular activities in the endocardium (Endo-LAVA) and epicardium (Epi-LAVA), followed by epicardial ablation if needed. From a total of 173 endocardial ablations targeting Epi-LAVA at the facing site, 48 (28%) applications (ICM: 20 of 71 [28%], NICM: 3 of 39 [8%], ARVC: 25 of 63 [40%]) successfully eliminated the Epi-LAVA. Presence of Endo-LAVA, the most delayed and low bipolar litude of Epi-LAVA, low unipolar litude in the facing endocardium, and Epi-LAVA within a wall thinning area at computed tomography scan were associated with successful ablation. Endocardial ablation could abolish all Epi-LAVA in 4 ICM and 2 ARVC patients, whereas all patients with NICM required epicardial ablation. Endocardial ablation was able to eliminate Epi-LAVA at least partially in 15 (83%) ICM, 2 (13%) NICM, and 11 (73%) ARVC patients, contributing to a potential reduction in epicardial RF applications. Pericardial bleeding occurred in 4 patients with epicardial ablation. Elimination of Epi-LAVA with endocardial RF delivery is feasible and might be used first to reduce the risk of epicardial ablation.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 02-2018
DOI: 10.1161/CIRCEP.117.005667
Abstract: Catheter ablation for atrial fibrillation has potential to cause esophageal thermal injury. Esophageal temperature monitoring during ablation is commonly used however, it has not eliminated thermal injuries, possibly because conventional sensors have poor spatial s ling and response characteristics. To enhance understanding of temperature dynamics that may underlie esophageal injury, we tested a high-resolution, intrabody, infrared thermography catheter to continuously image esophageal temperatures during ablation. Atrial fibrillation ablation patients were instrumented with a flexible, 9F infrared temperature catheter inserted nasally (n=8) or orally (n=8) into the esophagus adjacent to the left atrium. Ablation was performed while the infrared catheter continuously recorded surface temperatures from 7680 points per second circumferentially over a 6-cm length of esophagus. Physicians were blinded to temperature data. Endoscopy was performed within 24 hours to document esophageal injury. Thermal imaging showed that most patients (10/16) experienced ≥1 events where peak esophageal temperature was °C. Three patients experienced temperatures °C and 1 experienced °C. Analysis of temperature data for each subject’s maximum thermal event revealed high gradients (2.3±1.4°C/mm) and rates of change (1.5±1.3°C/s) with an average length of esophageal involvement of 11.0±5.4 mm. Endoscopy identified 3 distinct thermal lesions, all in patients with temperatures °C all resolved within 2 weeks. Infrared thermography provided dynamic, high-resolution mapping of esophageal temperatures during cardiac ablation. Esophageal thermal injury occurred with temperatures °C and was associated with large spatiotemporal gradients. Additional studies are warranted to determine the relationships between thermal parameters and esophageal injury.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 02-2015
DOI: 10.1161/CIRCEP.114.001943
Abstract: This study aimed to determine 5-year efficacy of catheter ablation for persistent atrial fibrillation (AF) using AF termination as a procedural end point. One hundred fifty patients (57±10 years) underwent persistent AF ablation using a stepwise ablation approach (pulmonary vein isolation, electrogram-guided, and linear ablation) with the desired procedural end point being AF termination. Repeat ablation was performed for recurrent AF or atrial tachycardia. AF was terminated by ablation in 120 patients (80%). Arrhythmia-free survival rates after a single procedure were 35.3%±3.9%, 28.0%±3.7%, and 16.8%±3.2% at 1, 2, and 5 years, respectively. Arrhythmia-free survival rates after the last procedure (mean 2.1±1.0 procedures) were 89.7%±2.5%, 79.8%±3.4%, and 62.9%±4.5%, at 1, 2, and 5 years, respectively. During a median follow-up of 58 (interquartile range, 43–73) months after the last ablation procedure, 97 of 150 (64.7%) patients remained in sinus rhythm without antiarrhythmic drugs. Another 14 (9.3%) patients maintained sinus rhythm after reinitiation of antiarrhythmic drugs, and an additional 15 (10.0%) patients regressed to paroxysmal recurrences only. Failure to terminate AF during the index procedure (hazard ratio 3.831 95% confidence interval, 2.070–7.143 P .001), left atrial diameter ≥50 mm (hazard ratio 2.083 95% confidence interval, 1.078–4.016 P =0.03), continuous AF duration ≥18 months (hazard ratio 1.984 95% confidence interval, 1.024–3.846 P .04), and structural heart disease (hazard ratio 1.874 95% confidence interval, 1.037–3.388 P =0.04) predicted arrhythmia recurrence. In patients with persistent AF, an ablation strategy aiming at AF termination is associated with freedom from arrhythmia recurrence in the majority of patients over a 5-year follow-up period. Procedural AF nontermination and specific baseline factors predict long-term outcome after ablation.
Publisher: Elsevier BV
Date: 04-2016
DOI: 10.1016/J.JACEP.2015.12.014
Abstract: This study sought to characterize the clinical characteristics, atrial substrate, and prognosis in a subgroup of patients with persistent atrial fibrillation (AF) from the onset (PsAFonset). Patients with AF frequently progress from trigger-driven paroxysmal arrhythmias to substrate-dependent persistent arrhythmias. Patients referred for persistent AF (PsAF) ablation were enrolled from 3 centers. Consecutive patients with PsAFonset (n = 129) were compared with patients with PsAF that progressed from paroxysmal AF (n = 231). In addition, 90 patients (30 patients with PsAFonset and 60 control subjects) were studied with noninvasive mapping to characterize the AF drivers. The degree of fractionation and endocardial voltages were assessed invasively. Patients with PsAFonset were younger (p = 0.047) and more obese (p < 0.001) there were more men (p = 0.034), more patients with hypertension (p = 0.044), and these patients had larger left (p < 0.05) and right atria (p < 0.05). Baseline AF cycle length was shorter in the PsAFonset group (p < 0.01) the degree of fractionation was higher (p < 0.001 for both atria), and the endocardial voltage was lower (p < 0.05 for both atria). Patients with PsAFonset had higher a number of re-entrant driver regions (p < 0.001) and extrapulmonary vein regions that had re-entrant drivers (p < 0.05), whereas control subjects displayed more focal driver regions (p = 0.029). The acute AF termination rate was lower in the PsAFonset group (42% vs. 81% p < 0.001). During a mean follow-up of 17 ± 11 months from the last procedure, patients with PsAFonset had significantly higher AF, atrial tachycardia (AT), and AF/AT recurrence rates (p < 0.01). Patients with PsAFonset represent a distinct subgroup defined by specific demographics, underlying diffuse biatrial substrate disease, and worse clinical outcome. The findings highlight the importance of defining criteria for early detection of atrial substrate disease.
Publisher: Oxford University Press (OUP)
Date: 06-2016
Publisher: Elsevier BV
Date: 04-2016
DOI: 10.1016/J.HRTHM.2015.11.020
Abstract: Inferolateral early repolarization (ER) is highly prevalent and is associated with idiopathic ventricular fibrillation (VF). The purpose of this study was to evaluate the potential role of T-wave parameters to differentiate between malignant and benign ER. We compared the ECGs of patients with ER and VF (n = 92) with control subjects with asymptomatic ER (n = 247). We assessed J-wave litude, QTc interval, T-wave/R-wave (T/R) ratio in leads II and V5, and presence of low- litude T waves (T-wave litude <0.1 mV and <10% of R-wave litude in lead I, II, or V4-V6). Compared to controls, the VF group had longer QTc intervals (388 ms vs. 377 ms, P = .001), higher J-wave litudes (0.23 mV vs. 0.17 mV, P <.001), higher prevalence of low- litude T waves (29% vs. 3%, P <.001), and lower T/R ratio (0.18 vs. 0.30, P <.001). Logistic regression analysis demonstrated that QTc interval (odds ratio [OR] per 10 ms: 1.15, 95% confidence interval [CI} 1.02-1.30), maximal J-wave litude (OR per 0.1 mV: 1.68, 95% CI 1.23-2.31), lower T/R ratio (OR per 0.1 unit: 0.62, 95% CI 0.47-0.81), presence of low- litude T waves (OR 3.53, 95% CI 1.26-9.88). and presence of J waves in the inferior leads (OR 2.58, 95% CI 1.18-5.65) were associated with malignant ER. Patients with malignant ER have a higher prevalence of low- litude T waves, lower T/R ratio (lead II or V5), and longer QTc interval. The combination of these parameters with J-wave litude and distribution of J waves may allow for improved identification of malignant ER.
Publisher: Elsevier BV
Date: 08-2016
Publisher: Wiley
Date: 08-10-2015
DOI: 10.1111/JCE.12825
Abstract: This study sought to determine if the acute procedural outcome of ventricular tachycardia (VT) substrate ablation is associated with a mortality benefit in patients with implantable cardioverter-defibrillators (ICD). A total of 195 ICD recipients (65 ± 11years) with ischemic or nonischemic dilated cardiomyopathy underwent substrate-based ablation targeting elimination of local abnormal ventricular activities (LAVA). Acute procedural success, which was defined as elimination of all identified LAVA in addition to the lack of VT inducibility, was achieved in 95 (49%) patients. During a median follow-up of 23 months, patients with acute procedure success had a significantly lower incidence of ICD shocks compared to those with ablation failure (8% vs. 30%, P < 0.001). In multivariate analysis, acute procedural success was associated with a lower risk of VT recurrence (hazard ratio [HR] 0.30, 95% confidence interval [CI] 0.18-0.49, P < 0.001) and all-cause mortality (HR 0.32, 95% CI 0.17-0.60, P 35% (HR 0.45, 95% CI 0.15-1.34, P = 0.15) and those with NYHA class I/II (HR 0.63, 95% CI 0.29-1.40, P = 0.26), it was marked in patients with LVEF ≤ 35% (HR 0.30, 95% CI 0.14-0.62, P = 0.001) and NYHA class III/IV (HR 0.17, 95% CI 0.05-0.57, P = 0.004). LAVA elimination in addition to VT noninducibility as a procedural outcome for substrate-based ablation is associated with reduced mortality and better VT-free survival during follow-up. This prognostic benefit may be most pronounced in patients with severe heart failure as indicated by severely depressed LV function and NYHA class III/IV symptoms.
Publisher: Elsevier BV
Date: 2011
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 10-2021
DOI: 10.1161/CIRCEP.120.009308
Abstract: A multielectrode saline-irrigated radiofrequency (RF) balloon catheter with an integrated camera system was designed to perform single-shot pulmonary vein (PV) isolation. To optimize ablation, simultaneous circumferential RF energy can be delivered, albeit with power output that is tailored to in idual electrodes based on direct visualization of tissue-electrode contact. In a first-in-human multicenter clinical trial, we studied the feasibility, performance, safety, and efficacy of PV isolation using this novel ablation catheter to treat atrial fibrillation. AF-FICIENT-I was a prospective, 5-center, single-arm study. After transseptal puncture, the RF balloon was positioned over the wire at each pulmonary (PV) ostium using a 13.3F sheath. RF energy was titrated based on visual contact (6–10 W up to 60 seconds per ablation). Electrical PV isolation was confirmed using either, (1) sensing mini-electrodes situated on the RF balloon itself or (2) a circular mapping catheter. Patients were clinically assessed for recurrent atrial arrhythmias lasting s over 12 months, after a 3-month blanking period. Six operators performed de novo PV isolation in 99 patients (95 paroxysmal/4 persistent age, 58±11 men, 67.7%). Median times, including procedure, fluoroscopy, ablation (time from first RF to last RF application), and balloon (time elapsing between catheter introduction to removal from the body) times, were 85 (interquartile range, 62–118), 14 (interquartile range, 9–23), 31 (interquartile range, 20–53), and 43 minutes (interquartile range, 32–70), respectively. The 12-month Kaplan-Meier estimates of freedom from any atrial arrhythmia (atrial fibrillation, atrial flutter, or atrial tachycardia) or atrial fibrillation alone were 77.5% (95% CI, 67.6%–84.7%) and 84.1% (95% CI, 74.9%–90.1%), respectively. There were no device-related serious adverse events. The novel RF balloon catheter allowed visually guided, directional titration of ablative energy to safely isolate PVs with short procedure times. URL: www.anzctr.org.au Unique identifier: ACTRN12615001340527.
Location: No location found
Location: France
No related grants have been discovered for Matthew Daly.