Performance and safety of temperature- and flow-controlled radiofrequency ablation for ventricular arrhythmia

AIMS High-power ablation is effective for ventricular arrhythmia ablation; however, it increases the risk of steam pops. The aim of this study was to define the safety and efficacy of QMODE ablation in the ventricle and the risk of steam pop. METHODS AND RESULTS Consecutive patients undergoing ventricular ablation using QDOT were included in a prospective single-centre registry. Procedural data, complications, and follow-up were systematically analysed and compared with a historical ventricular tachycardia (VT) and premature ventricular complexes (PVC) cohort ablated using STSF. QMODE (≤50 W) ablation was performed in 107 patients [age 62 ± 13 years; 76% male; VT (n = 41); PVC (n = 66)]. A total of 2456 applications were analysed [power: 45.9 ± 5.0 W with minimal power titration (90% > 95% max power); duration 26 ± 8 s; impedance drop 9.4 ± 4.7 Ω; ablation index: 569 ± 163; mean-max temperature 44.3 ± 2.6°C]. Ventricular tachycardia ablation was associated with shorter radiofrequency (RF) time and a trend towards shorter procedure times using QDOT (QDOT vs. STSF: 20.1 ± 14.7 vs. 31 ± 17 min; P = 0.002, 151 ± 59 vs. 172 ± 48 min; P = 0.06). Complications, VT recurrence, and mortality rates were comparable (QDOT vs. STSF: 2% vs. 2%; P = 0.9, 24% vs. 27%; P = 0.82, and 2% vs. 4%; P = 0.67). Five audible steam pops (0.02%) occurred. Premature ventricular complex ablation was associated with comparable RF and procedure times (QDOT vs. STSF: 4.8 ± 4.6 vs. 3.9 ± 3.1 min; P = 0.25 and 96.1 ± 31.9 vs. 94.6 ± 24.7 min; P = 0.75). Complication and PVC recurrence were also comparable (QDOT vs. STSF: 0% vs. 3%; P = 0.17 and 19% vs. 22%; P = 0.71). CONCLUSION Ventricular ablation using QMODE ≤ 50 W is safe and effective for both VT and PVC ablation and is associated with a low risk for steam pop

Evaluation of comprehensive geriatric assessment in older patients undergoing pacemaker implantation.

BACKGROUND This study evaluated the use of comprehensive geriatric assessment (CGA) in older patients undergoing pacemaker implantation. METHODS In this prospective cohort, CGA was performed in 197 patients ≥75 years at pacemaker implantation and yearly thereafter. CGA embraced the following domains: cognition, mobility, nutrition, activities of daily living (ADLs), and falls (with or without loss of consciousness). Based on comorbidities, the Charlson comorbidity index (CCI) was calculated. For predictive analysis, logistic regression was used. RESULTS During a mean follow-up duration of 2.4 years, the incidence rates of syncope decreased from 0.46 to 0.04 events per year (p < 0.001), and that of falls without loss of consciousness from 0.27 to 0.15 (p < 0.001) before vs. after implantation. Sixty-three patients (32.0%) died. Impaired mobility (OR 2.60, 95%CI 1.22-5.54, p = 0.013), malnutrition (OR 3.26, 95%CI 1.52-7.01, p = 0.002), and a higher CCI (OR per point increase 1.25, 95%CI 1.04-1.50, p = 0.019) at baseline were significant predictors of mortality. Among 169 patients who survived for more than 1 year and thus underwent follow-up CGA, CGA domains did not deteriorate during follow-up, except for ADLs. This decline in ADLs during follow-up was the strongest predictor of later nursing home admission (OR 9.29, 95%CI 1.82-47.49, p = 0.007). Higher baseline age (OR per year increase 1.10, 95%CI 1.02-1.20, p = 0.018) and a higher baseline CCI (OR per point increase 1.32, 95%CI 1.05-1.65, p = 0.017) were associated with a decline in ADLs during follow-up. CONCLUSIONS CGA is useful to detect functional deficits, which are associated with mortality or nursing home admission after pacemaker implantation. The present study seems to support the use of CGA in older patients undergoing pacemaker implantation as functional deficits and falls are amenable to geriatric interventions

Image-based Biophysical Simulation of Intracardiac Abnormal Ventricular Electrograms

International audienceGoal: In this work, we used in silico patient-specific models constructed from 3D delayed-enhanced magnetic resonance imaging (DE-MRI) to simulate intracardiac electrograms (EGM). These included electrically abnormal electrograms as these are potential radiofrequency ablation (RFA) targets. Methods: We generated signals with distinguishable macroscopic normal and abnormal characteristics by constructing MRI-based patient-specific structural heart models and by solving the simplified biophysical Mitchell-Schaeffer model of cardiac electrophysiology. Then, we simulated intracardiac electrograms by modelling a recording catheter using a dipole approach.Results: Qualitative results show that simulated EGM resemble clinical signals. Additionally, the quantitative assessment of signal features extracted from the simulated EGM showed statistically significant differences (p<0.0001) between the distributions of normal and abnormal electrograms, similarly to what is observed on clinical data.Conclusion: We demonstrate the feasibility of coupling simplified cardiac EP models with imaging data to generate intracardiac EMG. Significance: These results are a step forward in the direction of the pre-operative and non-invasive identification of ablation targets to guide RFA therapy

Confidence-based Training for Clinical Data Uncertainty in Image-based Prediction of Cardiac Ablation Targets

International audienceVentricular radio-frequency ablation (RFA) can have a critical impact on preventing sudden cardiac arrest but is challenging due to a highly complex arrhythmogenic substrate. This work aims to identify local image characteristics capable of predicting the presence of local abnormal ventricular activities (LAVA). This can allow, pre-operatively and non-invasively, to improve and accelerate the procedure. To achieve this, intensity and texture-based local image features are computed and random forests are used for classification. However using machine-learning approaches on such complex multimodal data can prove difficult due to the inherent errors in the training set. In this manuscript we present a detailed analysis of these error sources due in particular to catheter motion and the data fusion process. We derived a principled analysis of confidence impact on classification. Moreover, we demonstrate how formal integration of these uncertainties in the training process improves the algorithm's performance, opening up possibilities for non-invasive image-based prediction of RFA targets

Integrated hybrid Raman/fiber Bragg grating interrogation scheme for distributed temperature and point dynamic strain measurements

We propose and experimentally demonstrate the feasibility of an integrated hybrid optical fiber sensing interrogation technique that efficiently combines distributed Raman-based temperature sensing with fiber Bragg grating (FBG)-based dynamic strain measurements. The proposed sensing system is highly integrated, making use of a common optical source/receiver block and exploiting the advantages of both (distributed and point) sensing technologies simultaneously. A multimode fiber is used for distributed temperature sensing, and a pair of FBGs in each discrete sensing point, partially overlapped in the spectral domain, allows for temperature-independent discrete strain measurements. Experimental results report a dynamic strain resolution of 7.8  nε/√Hz within a full range of 1700 με and a distributed temperature resolution of 1°C at 20 km distance with 2.7 m spatial resolution

Characterization by imaging and high-density electrophysiology of substrates and ventricular arrhythmias

L'ablation par radiofréquence constitue un des traitements des tachycardies ventriculaires, en association avec les drogues anti-arythmiques et l’implantation d'un défibrillateur. L’objectif principal de cette thèse est de mieux comprendre le substrat arythmogène non seulement à l’aide d'imagerie cardiaque (IRM et scanner) de haute résolution et de cartographie de haute densité, en utilisant des cathéters multipolaires. Cela nous permettra d'analyser la relation structure-fonction. Nous avons étudié cette relation sur différents types de substrats (ICM, NICM, DAVD, et myocardites). Nous avons ainsi prouvé la supériorité de la cartographie de haute densité obtenue à partir de cathéters multipolaires, comparativement aux données recueillies par l’imagerie, dans l’identification de la cicatrice arythmogène et la détection des LAVA. La deuxième partie de cette thèse concerne l’étude du substrat arythmogène épicardique. Nous avons ainsi décrit la technique de cartographie par voie percutanée antérieure, puis démontré l'efficacité des procédures uniquement avec abord épicardique. La segmentation du nerf phrénique et des artères coronaires ont permis de diminuer le taux de complications théoriquement liés à cet abord. Nous avons poursuivi ce travail avec l’analyse des sites d'intérêt de l'ablation des TV: les LAVA. Après une description de la stratégie d’élimination des LAVA, nous avons tenté de trouver des prédicteurs permettant de localiser les sites de LAVA, à partir des données d'imagerie. Quand l'imagerie montre une cicatrice intraseptale ou intramurale, les LAVA ne peuvent pas être enregistrés avec la cartographie et des alternative techniques d'ablation sont nécessaires comme une ablation bipolaire, l'alcoolisation intra coronaire et l'ablation avec l'aiguille irriguée. Le dernier chapitre est une revue sur le futur de l'imagerie, de la cartographie et de l’ablation des tachycardies ventriculaires. Une meilleure compréhension du substrat arythmogène pourrait améliorer l'efficacité et la sécurité des ablations de tachycardie ventriculaire.Radiofrequency (RF) catheter ablation is an effective treatment strategy for scar-related ventricular tachycardia (VT), resistant to anti-arrhythmic drugs and intracardiac defibrillator (ICD) placement. The goal of this thesis was to better understand and characterize the arrhythmogenic VT substrate in different cardiomyopathic processes: ischaemic cardiomyopathy (ICM), non-ischaemic cardiomyopathy (NICM), arrhythmogenic right ventricular cardiomyopathy (ARVC) and myocarditis. For this purpose, we combined high resolution imaging including different modalities and high resolution electrical mapping to better understand the structure-function relationship. We focused on multiple different aspects of VT ablation as outlined below. The first part of this thesis focuses on the role of multipolar mapping catheters and imaging to analyze their structural and functional relationship. We demonstrated superiority of high density mapping with multipolar mapping on conventional mapping in detection of scar, channels, local abnormal ventricular activity (LAVA) and sensitivity for near field signals. The second part of this thesis focuses on ablation of epicardial VT substrate. We demonstrated the efficacy and safety of epicardial only procedures in a highly selected population. We used imaging to have access to the exact anatomy of the heart, to image the substrate but also to increase the safety of ablation procedures by imaging the phrenic nerve and the coronary artery system. The third part of this thesis focuses on analysis of the mapping and ablation of potential targets for scar-related VT ablation. Within this context, we identified predictors of interesting ablation (LAVA) sites based on preprocedural imaging. We also analyzed the role of alternative strategies such as bipolar ablation, ethanol ablation and irrigated needle ablation to ablate intramural and intraseptal substrate, 18 often resistant ablation targets. Overall, we demonstrate that novel imaging, mapping and ablation techniques potentially improve the outcome of VT ablation

Caracterisation par imagerie et électrophysiologie de haute densité de substrats et arythmies ventriculaires

Radiofrequency (RF) catheter ablation is an effective treatment strategy for scar-related ventricular tachycardia (VT), resistant to anti-arrhythmic drugs and intracardiac defibrillator (ICD) placement. The goal of this thesis was to better understand and characterize the arrhythmogenic VT substrate in different cardiomyopathic processes: ischaemic cardiomyopathy (ICM), non-ischaemic cardiomyopathy (NICM), arrhythmogenic right ventricular cardiomyopathy (ARVC) and myocarditis. For this purpose, we combined high resolution imaging including different modalities and high resolution electrical mapping to better understand the structure-function relationship. We focused on multiple different aspects of VT ablation as outlined below. The first part of this thesis focuses on the role of multipolar mapping catheters and imaging to analyze their structural and functional relationship. We demonstrated superiority of high density mapping with multipolar mapping on conventional mapping in detection of scar, channels, local abnormal ventricular activity (LAVA) and sensitivity for near field signals. The second part of this thesis focuses on ablation of epicardial VT substrate. We demonstrated the efficacy and safety of epicardial only procedures in a highly selected population. We used imaging to have access to the exact anatomy of the heart, to image the substrate but also to increase the safety of ablation procedures by imaging the phrenic nerve and the coronary artery system. The third part of this thesis focuses on analysis of the mapping and ablation of potential targets for scar-related VT ablation. Within this context, we identified predictors of interesting ablation (LAVA) sites based on preprocedural imaging. We also analyzed the role of alternative strategies such as bipolar ablation, ethanol ablation and irrigated needle ablation to ablate intramural and intraseptal substrate, 18 often resistant ablation targets. Overall, we demonstrate that novel imaging, mapping and ablation techniques potentially improve the outcome of VT ablation.L'ablation par radiofréquence constitue un des traitements des tachycardies ventriculaires, en association avec les drogues anti-arythmiques et l’implantation d'un défibrillateur. L’objectif principal de cette thèse est de mieux comprendre le substrat arythmogène non seulement à l’aide d'imagerie cardiaque (IRM et scanner) de haute résolution et de cartographie de haute densité, en utilisant des cathéters multipolaires. Cela nous permettra d'analyser la relation structure-fonction. Nous avons étudié cette relation sur différents types de substrats (ICM, NICM, DAVD, et myocardites). Nous avons ainsi prouvé la supériorité de la cartographie de haute densité obtenue à partir de cathéters multipolaires, comparativement aux données recueillies par l’imagerie, dans l’identification de la cicatrice arythmogène et la détection des LAVA. La deuxième partie de cette thèse concerne l’étude du substrat arythmogène épicardique. Nous avons ainsi décrit la technique de cartographie par voie percutanée antérieure, puis démontré l'efficacité des procédures uniquement avec abord épicardique. La segmentation du nerf phrénique et des artères coronaires ont permis de diminuer le taux de complications théoriquement liés à cet abord. Nous avons poursuivi ce travail avec l’analyse des sites d'intérêt de l'ablation des TV: les LAVA. Après une description de la stratégie d’élimination des LAVA, nous avons tenté de trouver des prédicteurs permettant de localiser les sites de LAVA, à partir des données d'imagerie. Quand l'imagerie montre une cicatrice intraseptale ou intramurale, les LAVA ne peuvent pas être enregistrés avec la cartographie et des alternative techniques d'ablation sont nécessaires comme une ablation bipolaire, l'alcoolisation intra coronaire et l'ablation avec l'aiguille irriguée. Le dernier chapitre est une revue sur le futur de l'imagerie, de la cartographie et de l’ablation des tachycardies ventriculaires. Une meilleure compréhension du substrat arythmogène pourrait améliorer l'efficacité et la sécurité des ablations de tachycardie ventriculaire

Modified Transseptal Puncture Technique in Challenging Septa: A Randomized Comparison to Conventional Technique

Background. Transseptal puncture (TSP) can be challenging. We compared safety and efficacy of a modified TSP technique (“mosquito” technique, MOSQ-TSP) to conventional TSP (CONV-TSP). Method. Patients undergoing AF ablation in whom first attempt of TSP did not result in left atrial (LA) pressure (failure to cross, FTC) were randomized to MOSQ-TSP (i.e., puncture of the fossa via a wafer-thin inner stylet) or CONV-TSP (i.e., additional punctures at different positions). Primary endpoint was LA access. Secondary endpoints were safety, time, fluoroscopic dose (dose-area product, DAP), and number of additional punctures from FTC to final LA access. Result. Of 384 patients, 68 had FTC (MOSQ-TSP, n=34 versus CONV-TSP, n=34). No complications were reported. In MOSQ-TSP, primary endpoint was 100% (versus 73.5%, p<0.002), median time to LA access was 72 s [from 37 to 384 s] (versus 326 s [from 75 s to 1936 s], p<0.002), mean DAP to LA access was 1778±2315 mGy/cm2 (versus 9347±10690 mGy/cm2, p<0.002), and median number of additional punctures was 2 [1 to 3] (versus 0, p<0.002). Conclusion. In AF patients in whom the first attempt of TSP fails, the “mosquito” technique allows effective, safe, and time sparing LA access. This approach might facilitate TSP in elastic, aneurysmatic, or fibrosed septa