Publications by authors named "Michel Haissaguerre"

596 Publications

Why Ablation of Sites With Purkinje Activation Is Antiarrhythmic: The Interplay Between Fast Activation and Arrhythmogenesis.

Front Physiol 2021 23;12:648396. Epub 2021 Mar 23.

Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands.

Ablation of sites showing Purkinje activity is antiarrhythmic in some patients with idiopathic ventricular fibrillation (iVF). The mechanism for the therapeutic success of ablation is not fully understood. We propose that deeper penetrance of the Purkinje network allows faster activation of the ventricles and is proarrhythmic in the presence of steep repolarization gradients. Reduction of Purkinje penetrance, or its indirect reducing effect on apparent propagation velocity may be a therapeutic target in patients with iVF.
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http://dx.doi.org/10.3389/fphys.2021.648396DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8021688PMC
March 2021

"Strategy after Vein of Marshall Ethanol Infusion added to catheter ablation of persistent atrial fibrillation: please, follow the line".

Heart Rhythm 2021 Apr 5. Epub 2021 Apr 5.

IHU Liryc, Electrophysiology and Heart Modeling Institute, fondation Bordeaux Université, F-33600 Pessac- Bordeaux, France; Bordeaux University Hospital (CHU), Cardio-Thoracic Unit, F-33600 Pessac, France; Univ. Bordeaux, Centre de recherche Cardio-Thoracique de Bordeaux, U1045, F-33000, Bordeaux, France.

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http://dx.doi.org/10.1016/j.hrthm.2021.03.041DOI Listing
April 2021

Left axis deviation in patients with non-ischemic heart failure and left bundle branch block is a purely electrical phenomenon.

Heart Rhythm 2021 Apr 5. Epub 2021 Apr 5.

Bordeaux University Hospital (CHU), Cardio-Thoracic Unit, 33600 Pessac-Bordeaux, France; IHU Liryc, Electrophysiology and Heart Modeling Institute, fondation Bordeaux Université, F-33600 Pessac-Bordeaux, France.

Background: Possible mechanisms of left axis deviation (LAD) in the setting of left bundle branch block (LBBB) include differences in cardiac electrophysiology, structure, or anatomical axis.

Objectives: We sought to clarify the mechanism(s) responsible for LAD in patients with LBBB.

Methods: Twenty-nine patients with non-ischemic cardiomyopathies and LBBB underwent non-invasive electrocardiographic mapping (ECGi), cardiac computed tomography, and magnetic resonance imaging in order to define ventricular electrical activation, characterize cardiac structure, and determine the heart anatomical axis.

Results: Sixteen patients had a normal QRS axis (NA, mean axis: 8±23°) whereas 13 patients had LAD (mean axis: -48±13°, p<0.001). Total activation times were longer in the LAD group (112±25 vs 91±14ms, p=0,01) due to delayed activation of the basal anterolateral region (107±10 vs 81±17ms, p<0.001). Left ventricular (LV) activation in patients with LAD was from apex-to-base, contrasting with a circumferential pattern of activation in patients with NA. The apex-to-base delay was therefore longer in the LA group (95±13 vs 64±21ms, p<0.001) and correlated with the QRS frontal axis (R=0,67, p<0.001). Both groups were comparable in LV end diastolic volume (295±84vs LAD: 310±91ml; p=0.69), LV mass (177±33 vs LAD: 180±37g, p=0.83) and anatomical axis.

Conclusion: Left axis deviation in left bundle branch block appears to be due to electrophysiological abnormalities rather than structural factors or the cardiac anatomical axis.
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http://dx.doi.org/10.1016/j.hrthm.2021.03.042DOI Listing
April 2021

Novel Low-Voltage MultiPulse Therapy to Terminate Atrial Fibrillation.

JACC Clin Electrophysiol 2021 Mar 25. Epub 2021 Mar 25.

George Washington University, Washington, DC, USA. Electronic address:

Objectives: This first-in-human feasibility study was undertaken to translate the novel low-voltage MultiPulse Therapy (MPT) (Cardialen, Inc., Minneapolis, Minnesota), which was previously been shown to be effective in preclinical studies in terminating atrial fibrillation (AF), into clinical use.

Background: Current treatment options for AF, the most common arrhythmia in clinical practice, have limited success. Previous attempts at treating AF by using implantable devices have been limited by the painful nature of high-voltage shocks.

Methods: Forty-two patients undergoing AF ablation were recruited at 6 investigational centers worldwide. Before ablation, electrode catheters were placed in the coronary sinus, right and/or left atrium, for recording and stimulation. After the induction of AF, MPT, which consists of up to a 3-stage sequence of far- and near-field stimulation pulses of varied amplitude, duration, and interpulse timing, was delivered via temporary intracardiac leads. MPT parameters and delivery methods were iteratively optimized.

Results: In the 14 patients from the efficacy phase, MPT terminated 37 of 52 (71%) of AF episodes, with the lowest median energy of 0.36 J (interquartile range: 0.14 to 1.21 J) and voltage of 42.5 V (interquartile range: 25 to 75 V). Overall, 38% of AF terminations occurred within 2 seconds of MPT delivery (p < 0.0001). Shorter time between AF induction and MPT predicted success of MPT in terminating AF (p < 0.001).

Conclusions: MPT effectively terminated AF at voltages and energies known to be well tolerated or painless in some patients. Our results support further studies of the concept of implanted devices for early AF conversion to reduce AF burden, symptoms, and progression.
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http://dx.doi.org/10.1016/j.jacep.2020.12.014DOI Listing
March 2021

Persistent Atrial Fibrillation Ablation in Cardiac Laminopathy: Electrophysiological Findings and Clinical Outcomes.

Heart Rhythm 2021 Mar 31. Epub 2021 Mar 31.

Hôpital Cardiologique du Haut-Lévêque, CHU Bordeaux, L'Institut de RYthmologie et modélisation Cardiaque (LIRYC), Université Bordeaux, France. Electronic address:

Background: Little is known about persistent atrial fibrillation (AF) ablation in patients with cardiac laminopathy (CLMNA).

Objective: We aimed to characterize atrial electrophysiological properties and to assess the long-term outcomes of persistent AF ablation in CLMNA patients.

Methods: All CLMNA patients referred in our center for persistent AF ablation were retrospectively included. Left atrium (LA) volume, left atrial appendage (LAA) cycle length (CL), inter-atrial conduction delay and LA voltage amplitude were analyzed during the ablation procedure. Sinus rhythm maintenance and LA contractile function were assessed during long-term follow-up.

Results: From 2011 to 2020, 8 patients were included (47 ± 14 years; 3 women). LA volume was 205.8 ± 43.7mL, LAA AF CL was 250.7 ± 85.6ms and inter-atrial conduction delay was 296.5 ± 110.1ms. Large low voltage areas (>50% of LA surface; < 0,5mV EGM) were recorded in all 8 patients. 2 patients had inadvertent LAA disconnection during ablation. All A wave recorded by pulsed doppler in sinus rhythm were < 30cm/s, before, and after AF ablation. Early arrhythmia recurrence was recorded in 7 (87%) patients (time to recurrence 4 ± 4 months; 1.5 procedures per patient). After a mean follow-up of 4.4 ± 3.2 years, 4 patients underwent ICD therapy for life threatening ventricular arrhythmia and 3 patients finally underwent heart transplantation (HT).

Conclusion: Persistent AF patients afflicted by CLMNA exhibit severe LA impairment due to large low-voltage areas, prolonged conduction velocity and reduced contractile function. Ablation procedures have a limited impact with a high recurrence rate.
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http://dx.doi.org/10.1016/j.hrthm.2021.03.040DOI Listing
March 2021

Differentiating atrial tachycardias with centrifugal activation: Lessons from high-resolution mapping.

Heart Rhythm 2021 Mar 29. Epub 2021 Mar 29.

Lyric Institute, CHU Bordeaux, Univ.Bordeaux, France.

Background: A centrifugal activation is not always the origin of a focal-AT (True-Focal), but a passive activation from the other structures (Pseudo-Focal).

Objective: We aimed to establish a method to differentiate 'True-focal' from 'Pseudo-Focal'.

Methods: In 49 centrifugal activations in 35 AT-patients, 12-lead ECG, activation map, atrial global activation histogram (GAH), and local electrograms were analyzed. GAH demonstrates the relation between the activation area and timing through the cycle-length, displayed with a normalized-value, ranging from 0 (smallest activation-area) to 1.0 (largest activation-area).

Results: Of 30 centrifugal activations observed in the septal region, 6 were 'True-Focal'. The remaining 24 were 'Pseudo-Focal', of which 23/24 (95.8%) were from the opposite chamber. P-wave/flutter-waves duration<200ms discriminated the 'True-Focal' from the 'Pseudo-Focal' (sensitivity=100%, specificity=54.5%, positive predictive value (PPV)=33.3%, and negative predictive value (NPV)=100%). Multiple-breakthrough ruled out the possibility of a 'True-Focal' AT. Other differentiating factors were an activation area within initial 20ms <5mm and a typical QS pattern-electrograms at the origin. Of 19 centrifugal activations observed outside septal regions, 7 were 'True-Focal' and 12 were 'Pseudo-Focal' exited from an epicardial structure: 10/12 (83.3%) were located around the LAA and ridge. Flutter-wave, GAH<0.05, and GAH<0.1 for more than 110ms of cycle-length differentiated a 'True' from a 'Pseudo-Focal' with sensitivity/NPV of 100%. GAH<0.1 for more than 40% of cycle-length simply discriminated a 'True' from a 'Pseudo' with 100% accuracy.

Conclusion: Centrifugal activation is not necessarily due to a focal AT but a passive activation. The activation map with the GAH in addition to 12-lead ECG and local-EGMs enables an accurate differentiation.
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http://dx.doi.org/10.1016/j.hrthm.2021.03.038DOI Listing
March 2021

Significance of manifest localized staining during ethanol infusion into the vein of Marshall.

Heart Rhythm 2021 Mar 16. Epub 2021 Mar 16.

Hôpital Cardiologique du Haut-Lévêque, CHU Bordeaux, L'Institut de RYthmologie et Modélisation Cardiaque (LIRYC), Université Bordeaux, Bordeaux, France.

Background: Localized staining due to venule injury is attributable to ethanol infusion into the vein of Marshall (Et-VOM).

Objective: The purpose of this study was to investigate adverse outcomes of localized staining during Et-VOM in patients undergoing ablation for atrial fibrillation.

Methods: Two hundred four patients (age 64 ± 10 years; 153 male) were sorted based on the aspect of localized staining. Staining of atrial myocardium that spread uniformly along the VOM vascular tree following selective VOM venography was considered normal, in contrast to predominantly localized staining that spread concentrically from a focal point due to vascular injury. Outcomes between the 2 groups were compared.

Results: Localized staining was observed in 27% of patients. No patients developed clinically significant pericardial effusions during Et-VOM; however, 7 patients developed pericardial effusions on the first postprocedural day (3.6% in patients with vs 3.4% in patients without localized staining). No significant difference was found in achievement of acute mitral isthmus (MI) block (96% vs 98%) and size of the endocardial low-voltage area (8.5 ± 4.1 cm vs 9.3 ± 5.3 cm) in patients with and without localized staining, respectively. Long-term follow-up was not impacted by localized staining. Freedom from recurrent atrial tachyarrhythmias (66% vs 76%) and durability of MI block (57% vs 54%) were not significantly different with and without localized staining. There were no cases of rehospitalization for pericarditis, chronic pericardial effusion, or heart failure.

Conclusion: In our study, localized staining was frequent but was not associated with clinically relevant impact or disadvantages.
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http://dx.doi.org/10.1016/j.hrthm.2021.03.023DOI Listing
March 2021

Ligament of Marshall ablation for persistent atrial fibrillation.

Pacing Clin Electrophysiol 2021 Mar 9. Epub 2021 Mar 9.

LIRYC, University of Bordeaux, CHU de Bordeaux, Bordeaux France, Service de Rhythmologie, Hôpital Cardiologique du Haut-Lévêque (Centre Hospitalier Universtaire de Bordeaux), Talence, Aquitaine, France.

Beyond pulmonary vein isolation, the two main additional strategies: Cox-Maze procedure or targeting of electrical signatures (focal bursts, rotational activities, meandering wavelets), remain controversial. High-density mapping of these arrhythmias has demonstrated firstly that a patchy lesion set is highly proarrhythmogenic, favoring macro-re-entry through conduction slowing and providing pivots for localized re-entry. Secondly, discrete anatomical structures such as the Vein or Ligament of Marshall (VOM/LOM) and the coronary sinus (CS) have epicardial muscular bundles that are more frequently involved in re-entry than previously thought. The Marshall Bundle can be ablated at any point along its course from the mid-to-distal coronary sinus to the left atrial appendage. If necessary, the VOM may be directly ablated using ethanol infusion to eliminate PV contributions and produce conduction block across the mistral isthmus. Ethanol ablation of the VOM, supplemented with RF ablation, may be more effective in producing conduction block at the mitral isthmus than repeat RF ablation alone.
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http://dx.doi.org/10.1111/pace.14208DOI Listing
March 2021

Ante-mortem characterization of sudden deaths as first-manifestation in Italy.

J Interv Card Electrophysiol 2021 Feb 27. Epub 2021 Feb 27.

Electrophysiology Department, LIRYC Institute, Bordeaux University Hospital, Bordeaux, France.

Purpose: There is a relative paucity of data on ante-mortem clinical characteristics of young (age 1 to 35 years) sudden death (SD) victims. The aim of the study was to characterize ante-mortem characteristics of SD victims, in a selected national cohort identified by a web search.

Methods: A dataset of all SD (January 2010 and December 2015) was built from national forensic data and medical records, integrated with Google search model. Families were contacted to obtain consent for interviews. Data were obtained on ante-mortem symptoms. ECG characteristics and autopsy data were available.

Results: Out of 301 SD cases collected, medical and family history was available in 132 (43.9%). Twenty-eight (21.1%) had a positive family history for SD. SD occurred during sport/effort in 76 (57.6%). One hundred twelve (85%) SD cases had no prior reported symptoms. Autopsy data were available in 100/132 (75.8%) cases: an extra cardiac cause was identified in 20 (20%). Among the 61 cases with a cardiac diagnosis, 21 (34%) had hypertrophic cardiomyopathy. Among the 19 (19%) victims without structural abnormalities, molecular autopsy identified pathogenic variants for channelopathies in 9 cases. Ten (10%) victims had no identifiable cause.

Conclusions: Most SD were due to cardiac causes and occurred in previously asymptomatic patients. SD events mainly occurred during strenuous activity. In a minority of cases, no cause was identified. The web-based selection criteria, and incomplete data retrieval, need to be carefully taken into account for data interpretation and reproducibility.
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http://dx.doi.org/10.1007/s10840-021-00949-5DOI Listing
February 2021

3D MRI of explanted sheep hearts with submillimeter isotropic spatial resolution: comparison between diffusion tensor and structure tensor imaging.

MAGMA 2021 Feb 27. Epub 2021 Feb 27.

IHU Liryc, Electrophysiology and Heart Modeling Institute, Hopital Xavier Arnozan, 33600, Pessac, France.

Objective: The aim of the study is to compare structure tensor imaging (STI) with diffusion tensor imaging (DTI) of the sheep heart (approximately the same size as the human heart).

Materials And Methods: MRI acquisition on three sheep ex vivo hearts was performed at 9.4 T/30 cm with a seven-element RF coil. 3D FLASH with an isotropic resolution of 150 µm and 3D spin-echo DTI at 600 µm were performed. Tensor analysis, angles extraction and segments divisions were performed on both volumes.

Results: A 3D FLASH allows for visualization of the detailed structure of the left and right ventricles. The helix angle determined using DTI and STI exhibited a smooth transmural change from the endocardium to the epicardium. Both the helix and transverse angles were similar between techniques. Sheetlet organization exhibited the same pattern in both acquisitions, but local angle differences were seen and identified in 17 segments representation.

Discussion: This study demonstrated the feasibility of high-resolution MRI for studying the myocyte and myolaminar architecture of sheep hearts. We presented the results of STI on three whole sheep ex vivo hearts and demonstrated a good correspondence between DTI and STI.
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http://dx.doi.org/10.1007/s10334-021-00913-4DOI Listing
February 2021

Dormant conduction in the right ventricular outflow tract unmasked by adenosine in a patient with Brugada syndrome.

J Cardiovasc Electrophysiol 2021 Apr 10;32(4):1182-1186. Epub 2021 Mar 10.

Department of Cardiac Pacing and Electrophysiology, IHU Liryc, Electrophysiology and Heart Modeling Institute, Univ. Bordeaux, Bordeaux University Hospital (CHU), Pessac-Bordeaux, France.

Recent data of electrophysiological mapping in patients with Brugada syndrome (BrS) suggest that the presence of an abnormal arrhythmogenic substrate in the epicardial right ventricular outflow tract is responsible for ST-segment elevation and ventricular fibrillation (VF). Complete elimination of the epicardial abnormal potentials normalizes Brugada-pattern electrocardiogram and suppresses VF recurrence. We herein report the first case of BrS in which an injection of adenosine unmasked dormant conduction in the epicardial RVOT after the disappearance of the epicardial potentials.
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http://dx.doi.org/10.1111/jce.14974DOI Listing
April 2021

Use of high-density activation and voltage mapping in combination with entrainment to delineate gap-related atrial tachycardias post atrial fibrillation ablation.

Europace 2021 Feb 10. Epub 2021 Feb 10.

Electrophysiology and Ablation Unit, Hôpital Cardiologique du Haut Lévêque, Avenue de Magellan, 33604 Pessac Cedex, France.

Aims: An incomplete understanding of the mechanism of atrial tachycardia (AT) is a major determinant of ablation failure. We systematically evaluated the mechanisms of AT using ultra-high-resolution mapping in a large cohort of patients.

Methods And Results: We included 107 consecutive patients (mean age: 65.7 ± 9.2 years, males: 81 patients) with documented endocardial gap-related AT after left atrial ablation for persistent atrial fibrillation (AF). We analysed the mechanism of 134 AT (94 macro-re-entries and 40 localized re-entries) using high-resolution activation mapping in combination with high-density voltage and entrainment mapping. Voltage in the conducting channels may be extremely low, even <0.1 mV (0.14 ± 0.095 mV, 51 of 134 AT, 41%), and almost always <0.5 mV (0.03-0.5 mV, 133 of 134 AT, 99.3%). The use of multipolar Orion, HDGrid, and Pentaray catheters improved our accuracy in delineating ultra-low-voltage areas critical for maintenance of the circuit of endocardial gap-related AT. Conventional ablation catheters often do not detect any signal (noise level) even using adequate contact force, and only multipolar catheters of small electrodes and shorter interelectrode space can detect clear fractionated low-amplitude and high frequency signals, critical for re-entry maintenance. We performed a diagnosis in 112 out of 134 AT (83.6%) using only activation mapping and in 134 out of 134 AT (100%) using the combination of activation and entrainment mapping.

Conclusion : High-resolution activation mapping in combination with high-density voltage and entrainment mapping is the ideal strategy to delineate the critical part of the circuit in endocardial gap-related re-entrant AT after AF ablation.
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http://dx.doi.org/10.1093/europace/euaa394DOI Listing
February 2021

Ultralow temperature cryoablation: Safety and efficacy of preclinical atrial and ventricular lesions.

J Cardiovasc Electrophysiol 2021 Mar 1;32(3):570-577. Epub 2021 Feb 1.

IHU LIRYC ANR-10-IAHU-04, Electrophysiology and Heart Modeling Institute, University of Bordeaux, Bordeaux-Pessac, France.

Background: Ultralow temperature cyroablation (ULTC) is designed to create focal, linear, and circumferential lesions. The aim of this study was to assess the safety, efficacy, and durability of atrial and ventricular ULTC lesions in preclinical large animal models.

Methods And Results: The ULTC system uses nitrogen near its liquid-vapor critical point to cool 11-cm ablation catheters. The catheter can be shaped to specific anatomies using pre-shaped stylets. ULTC was used in 11 swine and four sheep to create atrial (pulmonary vein isolation and linear ablation) and ventricular lesions. Acute and 90-day success were evaluated by intracardiac mapping and histologic examination. Cryoadherence was observed during all ULTC applications, ensuring catheter stability at target locations. Local electrograms were completely eliminated immediately after the first single-shot ULTC application in 49 of 53 (92.5%) atrial and in 31 of 32 (96.9%) ventricular applications. Lesion depth as measured on histology preparations was 1.96 ± 0.8 mm in atrial and 5.61 ± 2.2 mm in ventricular lesions. In all animals, voltage maps and histology demonstrated transmural and durable lesions without gaps, surrounded by intact collagen fibers without injury to surrounding tissues. Transient coronary spasm could be provoked with endocardial ULTC in the left ventricle in close proximity to a coronary artery.

Conclusions: ULTC created effective and efficient atrial and ventricular lesions in vivo without procedural complications in two large animal models. ULTC lesions were transmural, contiguous, and durable over 3 months.
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http://dx.doi.org/10.1111/jce.14907DOI Listing
March 2021

On the nature of delays allowing anatomical re-entry involving the Purkinje network: a simulation study.

Europace 2021 Mar;23(Supplement_1):i71-i79

IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, F-33600 Pessac-Bordeaux, France.

Aims: Clinical observations suggest that the Purkinje network can be part of anatomical re-entry circuits in monomorphic or polymorphic ventricular arrhythmias. However, significant conduction delay is needed to support anatomical re-entry given the high conduction velocity within the Purkinje network.

Methods And Results: We investigated, in computer models, whether damage rendering the Purkinje network as either an active lesion with slow conduction or a passive lesion with no excitable ionic channel, could explain clinical observations. Active lesions had compromised sodium current and a severe reduction in gap junction coupling, while passive lesions remained coupled by gap junctions, but modelled the membrane as a fixed resistance. Both types of tissue could provide significant delays of over 100 ms. Electrograms consistent with those obtained clinically were reproduced. However, passive tissue could not support re-entry as electrotonic coupling across the delay effectively increased the proximal refractory period to an extremely long interval. Active tissue, conversely, could robustly maintain re-entry.

Conclusion: Formation of anatomical re-entry using the Purkinje network is possible through highly reduced gap junctional coupling leading to slowed conduction.
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http://dx.doi.org/10.1093/europace/euaa395DOI Listing
March 2021

Accuracy of a Smartwatch-Derived ECG for Diagnosing Bradyarrhythmias, Tachyarrhythmias, and Cardiac Ischemia.

Circ Arrhythm Electrophysiol 2021 01 14;14(1):e009260. Epub 2021 Jan 14.

Bordeaux University Hospital (CHU), Cardio-Thoracic Unit, F-33600 Pessac, France (T.C., H.M., S.B., N.W., S.P., M.H., P.B.).

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http://dx.doi.org/10.1161/CIRCEP.120.009260DOI Listing
January 2021

High-risk atrioventricular block in Brugada syndrome patients with a history of syncope.

J Cardiovasc Electrophysiol 2021 Mar 19;32(3):772-781. Epub 2021 Jan 19.

Department of Cardiovascular Medicine, Division of Arrhythmia and Electrophysiology, National Cerebral and Cardiovascular Center, Osaka, Japan.

Background: Determining the etiology of syncope is challenging in Brugada syndrome (BrS) patients. Implantable cardioverter defibrillator placement is recommended in BrS patients who are presumed to have arrhythmic syncope. However, arrhythmic syncope in BrS patients can occur in the setting of atrioventricular block (AVB), which should be managed by cardiac pacing. The clinical characteristics of BrS patients with high-risk AVB remain unknown.

Methods: This study included 223 BrS patients with a history of syncope from two centers. The clinical characteristics of patients with high-risk AVB (Mobitz type II second-degree AVB, high-degree AVB, or third-degree AVB) were investigated.

Results: During the 99 ± 78 months of follow-up, we identified six BrS patients (2.7%) with high-risk AVB. Three of the six patients (50%) with AVB presented with syncope associated with prodromes or specific triggers. Four patients (67%) were found to have paroxysmal third-degree AVB during the initial evaluation for BrS and syncope, while two patients developed third-degree AVB during the follow-up period. The incidence of first-degree AVB was significantly higher in AVB patients than in non-AVB patients (83% vs. 15%; p = .0005). There was no significant difference in the incidence of ventricular fibrillation between AVB and non-AVB patients (AVB [17%], non-AVB [12%]; p = .56).

Conclusion: High-risk AVB can occur in BrS patients with various clinical presentations. Although rare, the incidence is worth considering, especially in BrS patients with first-degree AVB.
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http://dx.doi.org/10.1111/jce.14876DOI Listing
March 2021

Transcatheter ablation for atrial fibrillation in patients with hypertrophic cardiomyopathy: Long-term results and clinical outcomes.

J Cardiovasc Electrophysiol 2021 Mar 24;32(3):657-666. Epub 2021 Jan 24.

Division of Cardiology, Department of Medical Sciences, "Città della Salute della Scienza" Hospital, University of Turin, Turin, Italy.

Introduction: Radiofrequency transcatheter ablation (RFCA) for atrial fibrillation (AF) in patients with hypertrophic cardiomyopathy (HCM) has been proven feasible. However, the long-term results of RFCA and its impact on clinical course of HCM are unknown. The aim of this study was to analyse clinical outcomes and long-term efficacy of RFCA in a multicentre cohort of patients with HCM and concomitant AF.

Methods: Patients with HCM and AF consecutively undergoing RFCA were included. Ablation failure was defined as recurrence of AF, atrial tachycardia, or flutter lasting more than 3 min and occurring after the blanking period.

Results: Overall, 116 patients with symptomatic AF refractory to antiarrhythmic drugs were included. Over a median follow-up of 6.0 years (interquartile range: 3.0-8.9 years) recurrence rate after a single RFCA was 32.3 per 100 patient/years with 26% of patients free from AF relapses at 6-year follow-up. Among patients experiencing AF recurrence, 51 (66%) underwent at least one redo-procedure. The overall recurrence rate considering redo-procedures was 12.6 per 100 patients/years with 53% of patients free from AF relapses at 6 years. At last follow-up, with an average of 1.6 procedures, 67 (61%) patients were in sinus rhythm (SR). Patients remaining in SR showed better functional status compared with those experiencing arrhythmic recurrences (NYHA Class 1.6 ± 0.1 vs. 2.0 ± 0.1, p = .009).

Conclusions: RFCA of AF in HCM patients is an effective and safe strategy favoring long-term SR maintenance, reduction of atrial arrhythmic events, and improved functional status. However, most patients need repeat procedures and continuation of antiarrhythmic drugs.
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http://dx.doi.org/10.1111/jce.14880DOI Listing
March 2021

Marshall bundle elimination, Pulmonary vein isolation, and Line completion for ANatomical ablation of persistent atrial fibrillation (Marshall-PLAN): Prospective, single-center study.

Heart Rhythm 2021 Apr 29;18(4):529-537. Epub 2020 Dec 29.

IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Pessac-Bordeaux, France; Bordeaux University Hospital (CHU), Cardio-Thoracic Unit, Pessac, France.

Background: Beyond pulmonary vein isolation (PVI), the optimal ablation strategy for persistent atrial fibrillation (AF) remains poorly defined.

Objective: The purpose of this study was to examine a novel comprehensive ablation strategy (Marshall bundle elimination, Pulmonary vein isolation, and Line completion for ANatomical ablation of persistent atrial fibrillation [Marshall-PLAN]) strictly based on anatomical considerations.

Methods: Left atrial (LA) sites were sequentially targeted as follows: (1) coronary sinus and vein of Marshall (CS-VOM) musculature; (2) PVI; and (3) anatomical isthmuses (mitral, roof, and cavotricuspid isthmus [CTI]). The primary endpoint was 12-month freedom from AF/atrial tachycardia (AT).

Results: Seventy-five consecutive patients were included (age 61 ± 9 years; 10 women; AF duration 9 ± 11 months; mean LA volume 197 ± 43 mL). VOM ethanol infusion was completed in 69 patients (92%). The full Marshall-PLAN lesion set (VOM, PVI, mitral, roof, and CTI with block) was successfully completed in 68 patients (91%). At 12 months, 54 of 75 patients (72%) were free from AF/AT after a single procedure (no antiarrhythmic drugs) in the overall cohort. In the subset of patients with a complete Marshall-PLAN lesion set (n = 68), the single procedure success rate was 79%. After 1 or 2 procedures, 67 of 75 patients (89%) remained free from AF/AT (no antiarrhythmic drugs). After 1 or 2 procedures, VOM ethanol infusion was complete in 72 of 75 patients (96%).

Conclusion: A novel ablation strategy that systematically targets anatomical atrial structures (VOM ethanol infusion, PVI, and prespecified linear lesions) is feasible, safe, and associated with a high rate of freedom from arrhythmia recurrence at 12 months in patients with persistent AF.
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http://dx.doi.org/10.1016/j.hrthm.2020.12.023DOI Listing
April 2021

Impact of Vein of Marshall Ethanol Infusion on Mitral Isthmus Block: Efficacy and Durability.

Circ Arrhythm Electrophysiol 2020 12 16;13(12):e008884. Epub 2020 Nov 16.

Bordeaux University Hospital (CHU), Cardiac Electrophysiology and Cardiac Stimulation Team, CHU Bordeaux, IHU Lyric, Université de Bordeaux, France (T.N., T.P., K.V., C.G., C.A., P.K., F.D.R., T. Kamakura, T.T., Y.N., T. Kitamura, M.T., G.C., R.T., R.C., N.W., J.D., F.S., H.C., M. Hocini, M. Haïssaguerre, P.J., N.D.).

Background: Achieving bidirectional mitral isthmus (MI) block using radiofrequency catheter ablation (RFCA) alone is challenging, and MI reconnection is common. Adjunctive vein of Marshall (VOM) ethanol infusion (VOM-Et) can facilitate acute MI block. However, little is known about its long-term success. This study sought to evaluate the impact of adjunctive VOM-Et on MI block achievement and durability compared with RFCA alone.

Methods: Patients undergoing the first attempt of posterior MI ablation were grouped according to their MI block index strategy: adjunctive VOM-Et and RFCA alone. Rates of acute MI block and MI reconnection observed during repeat procedures were compared between the 2 groups.

Results: The VOM-Et group consisted of 152 patients (63.8±9.4 years) undergoing adjunctive VOM-Et for MI block. The RFCA group consisted of 110 patients (60.9±9.2 years) undergoing MI ablation using RFCA alone. Acute MI block was more frequently achieved in the VOM-Et group (98.7% [150/152] versus 63.6% [70/110]; <0.001) with shorter RFCA duration (5.00 [3.00-7.00] versus 19.0 [13.6-22.0] minutes; <0.001). Of the 220 patients with MI block achieved during the index procedure, 81 underwent a repeat procedure during follow-up (VOM-Et group: 23.3% [35/150] versus RFCA group: 65.7% [46/70], respectively; <0.001). A significantly greater number of patients exhibited durable MI block in the VOM-Et group (62.9% [22/35] versus 32.6% [15/46], respectively; =0.008).

Conclusions: Beyond facilitating acute MI block, VOM-Et is associated with greater lesion durability as evidenced by higher rates of MI block during repeat procedures.
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http://dx.doi.org/10.1161/CIRCEP.120.008884DOI Listing
December 2020

Epicardial course of the septopulmonary bundle: Anatomical considerations and clinical implications for roof line completion.

Heart Rhythm 2021 Mar 11;18(3):349-357. Epub 2020 Nov 11.

Hôpital Cardiologique du Haut-Lévêque, CHU Bordeaux, L'Institut de RYthmologie et modélisation Cardiaque (LIRYC), Université Bordeaux, Bordeaux, France.

Background: Gaps in the roof line have been ascribed to epicardial conduction using the septopulmonary bundle.

Objectives: We sought to evaluate the frequency of septopulmonary bundle bypass during roof line ablation, to describe anatomical conditions favoring this epicardial gap, and to propose an alternative strategy when present.

Methods: One hundred consecutive patients underwent atrial fibrillation ablation. A de novo roof line was created between the superior pulmonary veins. In cases of residual gaps, a floor line was created between the inferior pulmonary veins. Microtomography imaging and histological analyses of 5 human donor hearts were performed: a specific focus was made on the dome and the posterior wall.

Results: Residual gaps were more frequent in roof lines than floor lines (33% vs 15%; P = .049). Electrogram morphologies, activation sequences, and pacing maneuvers indicated an epicardial bypass of the roof line in all cases. Conduction block was obtained in 67 roof lines and 28 floor lines, resulting in a 95% success rate of linear block, without "box" isolation. Between the superior pulmonary veins, the atrial myocardium was thicker and consistently displayed adipose tissue separating the septopulmonary bundle from the septoatrial bundle.

Conclusion: Epicardial conduction across the roof line is common and requires careful electrogram analysis to detect. In such cases, a floor line can be an effective alternative strategy, with clear validation criteria. Myocardial thickness and fat interposition may explain difficulties in achieving lesion transmurality during roof line ablation.
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http://dx.doi.org/10.1016/j.hrthm.2020.11.008DOI Listing
March 2021

Temperature- and flow-controlled ablation/very-high-power short-duration ablation vs conventional power-controlled ablation: Comparison of focal and linear lesion characteristics.

Heart Rhythm 2021 Apr 27;18(4):553-561. Epub 2020 Oct 27.

Hôpital Cardiologique Haut Lévêque, Lyric Institute, Université de Bordeaux, Pessac, France.

Background: The QDOT MICRO catheter allows temperature- and flow-controlled (TFC) ablation and very-high-power short-duration (vHPSD) ablation.

Objective: The purpose of this study was to compare lesion characteristics between TFC/vHPSD ablation and standard power-controlled (PC) ablation.

Methods: Lesion characteristics in the right atrium, left atrium, and right ventricle (RV) of 6 sheep were compared between vHPSD (90 W/4 seconds, TC mode with 60°C target using QDOT) and standard radiofrequency settings (PC mode, 30 W/30 seconds with ThermoCool SmartTouch SF). Lesions in the left ventricle (LV) were compared, targeting 50 W for 60-second applications.

Results: Forty-six focal atrial lesions, 50 RV focal lesions, and 12 linear lesions were created by vHPSD ablation and PC ablation in each group of 6 animals. vHPSD ablation produced significantly larger focal atrial lesions in length (8.3 [6.4-9.7] mm vs 6.3 [5.2-7.4] mm; P = .0002), width (6.0 [5.3-6.9] mm vs 4.6 [3.8-5.4] mm; P <.0001), and surface area (39.4 [25.4-52.4] mm vs 23.6 [16.0-31.1] mm; P = .0001), with superior transmurality (89.1% vs 69.6%; P = .04) compared to PC ablation. vHPSD ablation produced significantly larger RV lesions in length (7.7 [7.0-8.7] mm vs 6.0 [4.8-6.9] mm; P <.0001), width (6.4 [5.4-7.5] mm vs 4.3 [3.6-5.2] mm; P <.0001), and area (39.4 [29.1-50.1] mm vs 19.9 [14.7-25.2] mm; P <.0001) but similar volume (P = .97) with shallower lesions (2.7 [2.2-3.4] mm vs 3.8 [3.0-4.4] mm; P <.0001). Atrial linear lesions were more homogeneous (P = .02), with fewer gaps in each line (P = .003) with vHPSD ablation. LV focal lesions (15 TFC mode; 21 PC mode) were similar in volume and depth, but lesion size showed less deviation (P <.05) in TFC than PC mode. Fewer steam pops were observed in TFC mode (0% vs 28.6%; P = .03). Hemorrhagic rings around the lesion core were generally smaller with TFC/vHPSD ablation (P <.05).

Conclusion: TFC/vHPSD ablation produces larger, shallower, more homogeneous, and less hemorrhagic lesions. vHPSD Ablation produces more transmural and contiguous linear lesions compared to PC ablation. LV lesions are more homogeneous with fewer steam pops in TFC ablation.
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http://dx.doi.org/10.1016/j.hrthm.2020.10.021DOI Listing
April 2021

Structurally Abnormal Myocardium Underlies Ventricular Fibrillation Storms in a Patient Diagnosed With the Early Repolarization Pattern.

JACC Clin Electrophysiol 2020 10 16;6(11):1395-1404. Epub 2020 Sep 16.

Department of Experimental Cardiology, Amsterdam Cardiovascular Sciences, University of Amsterdam, Amsterdam University Medical Centers, Amsterdam, the Netherlands; IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Pessac-Bordeaux, France. Electronic address:

Objectives: The aim of this study was to investigate the mechanism underlying QRS-slurring in a patient with the early repolarization pattern in the electrocardiogram (ECG) and ventricular fibrillation (VF) storms.

Background: The early repolarization pattern refers to abnormal ending of the QRS complex in subjects with structurally normal hearts and has been associated with VF.

Methods: We studied a patient with slurring of the QRS complex in leads II, III, and aVF of the ECG and recurrent episodes of VF. Echocardiographic and imaging studies did not reveal any abnormalities. Endocardial mapping was normal but subxyphoidal epicardial access was not possible. Open chest epicardial mapping was performed.

Results: Mapping showed that the inferior right ventricular free wall activated the latest with local J-waves in unipolar electrograms. The last moment of epicardial activation concurred with QRS-slurring in the ECG whereas the J-waves in the local unipolar electrograms occurred in the ST-segment of the ECG. Myocardial biopsies obtained from the late activated tissue showed severe fibrofatty alterations in the inferior right ventricular wall where fractionation and local J-waves were present. After ablation, the early repolarization pattern in the ECG disappeared and arrhythmias have been absent since (follow-up 18 months).

Conclusions: In this patient, the electrocardiographic early repolarization pattern was caused by late activation due to structurally abnormal myocardium. The late activated areas were marked by J-waves in local electrograms. Ablation of these regions prevented arrhythmia recurrence and normalized the ECG.
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http://dx.doi.org/10.1016/j.jacep.2020.06.027DOI Listing
October 2020

Automated rhythm-based control of radiofrequency ablation close to the atrioventricular node: Preclinical, animal, and first-in-human testing.

Heart Rhythm 2020 Oct 20. Epub 2020 Oct 20.

L'Institut de RYthmologie et Modélisation Cardiaque (LIRYC), Pessac, Bordeaux, France; Cardiology Department, Hôpital Haut-Lévèque, Pessac, Bordeaux, France.

Background: The risk of heart block during radiofrequency ablation of atrioventricular (AV) nodal reentrant tachycardia and septal accessory pathways is minimized by rapidly ceasing ablation in response to markers of risk, such as atrioventricular dissociation, fast junctional rhythm, PR interval prolongation, or 2 consecutive atrial or ventricular depolarizations. Currently this is done manually.

Objectives: The objectives of this study were to build and test a control system able to monitor cardiac rhythm and automatically terminate ablation energy when required.

Methods: The device was built from off-shelf componentry. Preclinical testing involved real-time input of electrogram/electrocardiogram data from 209 ablation procedures (20 patients) over slow (n = 19) and fast (n = 1) AV nodal pathways. The device response speed was compared with the human response speed. The device's ability to prevent heart block was tested in 5 sheep. First-in-human testing was then performed in 12 patients undergoing AV nodal reentrant tachycardia ablation.

Results: Risk conditions necessitating shutoff of ablation (200 total; 111 preclinical and 89 first-in-human) were detected by the device with 100% sensitivity and 94% specificity, automatically terminating ablation while still allowing successful ablation in all patients. Device shutoff of ablation was always faster than human response (median difference 1.24 seconds). In each of 5 sheep, 40 consecutive attempts to cause heart block by ablating over the His bundle were unsuccessful because of automatic shutoff in response to rhythm change.

Conclusion: Automated shutoff of ablation close to the AV node in response to markers of the risk of heart block is feasible with high accuracy as well as faster response than human response. The system may improve the safety of ablation near the AV node by preventing heart block.
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http://dx.doi.org/10.1016/j.hrthm.2020.10.014DOI Listing
October 2020

Insights Into the Spatiotemporal Patterns of Complexity of Ventricular Fibrillation by Multilead Analysis of Body Surface Potential Maps.

Front Physiol 2020 23;11:554838. Epub 2020 Sep 23.

Institute of Electrophysiology and Heart Modeling (IHU Liryc), Foundation Bordeaux University, Bordeaux, France.

Background: Ventricular fibrillation (VF) is the main cause of sudden cardiac death, but its mechanisms are still unclear. We propose a noninvasive approach to describe the progression of VF complexity from body surface potential maps (BSPMs).

Methods: We mapped 252 VF episodes (16 ± 10 s) with a 252-electrode vest in 110 patients (89 male, 47 ± 18 years): 50 terminated spontaneously, otherwise by electrical cardioversion (DCC). Changes in complexity were assessed between the onset ("VF start") and the end ("VF end") of VF by the nondipolar component index ( ), measuring the fraction of energy nonpreserved by an equivalent 3D dipole from BSPMs. Higher NDI reflected lower VF organization. We also examined other standard body surface markers of VF dynamics, including fibrillatory wave amplitude ( ), surface cycle length ( ) and Shannon entropy ( ). Differences between patients with and without structural heart diseases (SHD, 32 vs. NSHD, 78) were also tested at those stages. Electrocardiographic features were validated with simultaneous endocardium cycle length (CL) in a subset of 30 patients.

Results: All BSPM markers measure an increase in electrical complexity during VF ( < 0.0001), and more significantly in NSHD patients. Complexity is significantly higher at the end of sustained VF episodes requiring DCC. Intraepisode intracardiac CL shortening (VF start 197 ± 24 vs. VF end 169 ± 20 ms; < 0.0001) correlates with an increase in NDI, and decline in surface CL, f-wave amplitude, and entropy ( < 0.0001). In SHD patients VF is initially more complex than in NSHD patients ( , = 0.0007; , < 0.0001), with moderately slower ( , = 0.06), low-amplitude f-waves ( , < 0.0001). In this population, lower NDI ( = 0.004) and slower surface CL ( = 0.008) at early stage of VF predict self-termination. In the NSHD group, a more abrupt increase in VF complexity is quantified by all BSPM parameters during sustained VF ( < 0.0001), whereas arrhythmia evolution is stable during self-terminating episodes, hinting at additional mechanisms driving VF dynamics.

Conclusion: Multilead BSPM analysis underlines distinct degrees of VF complexity based on substrate characteristics.
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http://dx.doi.org/10.3389/fphys.2020.554838DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7538856PMC
September 2020

The 'double transition': a novel electrocardiogram sign to discriminate posteroseptal accessory pathways ablated from the right endocardium from those requiring a left-sided or epicardial coronary venous approach.

Europace 2020 11;22(11):1703-1711

Electrophysiology Department, Hôpital Cardiologique du Haut-Lévêque and Université de Bordeaux, IHU LIRYC ANR-10-IAHU-04, Bordeaux-Pessac, France.

Aims: The precise localization of manifest posteroseptal accessory pathways (APs) often poses diagnostic challenges considering that a small area may encompass AP that may be ablated from the right or left endocardium, or epicardially within the coronary sinus (CS). We sought to explore whether the QRS transition pattern in the precordial lead may help to discriminate the necessary ablation approach.

Methods And Results: Consecutive patients who underwent a successful ablation of a single manifest AP over a 5-year period were included. Standard 12-lead electrocardiograms were reviewed. A total of 273 patients were identified. Mean age was 31 ± 15 years and 62% were male. Of the 110 identified posteroseptal AP, 64 were ablated from the right endocardium, 33 from the left endocardium, and 13 inside the CS. While a normal precordial QRS transition was most often observed, a subset of 33 patients presented an atypical 'double transition' pattern which specifically identified right endocardial AP. The combination of a q wave in V1 with a proportion of the positive QRS component in V1 < V2 > V3, predicted a right endocardial AP with a 100% specificity. In case of a positive QRS sum in V2, this 'double transition' pattern predicted a posteroseptal right endocardial AP with 99.5% specificity and 44% sensitivity. The positive predictive value was 97%. The only false positive was a midseptal AP. In the case of a negative or isoelectric QRS sum in V2, APs were located more laterally on the tricuspid annulus.

Conclusion: The combination of a q wave in V1 with a double QRS transition pattern in the precordial leads is highly specific of a right endocardial AP and rules out the need for CS or left-sided mapping.
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http://dx.doi.org/10.1093/europace/euaa200DOI Listing
November 2020

Long-Lasting Ventricular Fibrillation in Humans ECG Characteristics and Effect of Radiofrequency Ablation.

Circ Arrhythm Electrophysiol 2020 10 10;13(10):e008639. Epub 2020 Sep 10.

LIRYC Institute/INSERM 1045, Bordeaux University, France (J.D., M. Hocini, F.S., P.J., O.B., M. Haïssaguerre, R.D.).

Background: Studies of ventricular fibrillation (VF) in humans are limited because of the short available duration. We sought to study surface ECG waveforms and effect of ablation in long-lasting VF in patients with left assist devices.

Methods: Continuous 12-lead ECG of 5 episodes of long-lasting VF occurring in 3 patients with left ventricular assist device were analyzed. Spectral analysis (dominant frequency) and quantification of waveform amplitude, regularity (Unbiased Regularity Index), and complexity (Nondipolar Index) were performed over a median of 24 minutes of VF. Radiofrequency ablation was performed during VF in 2 patients.

Results: There was a significant increase in dominant frequency between VF onset and termination but none of the other parameters significantly changed. Some VF parameters varied from patient to patient and from lead to lead. Dominant frequency decreased after radiofrequency ablation in both cases and VF terminated spontaneously shortly after ablation in one case. The previously incessant VFs in these 2 patients did not recur afterward.

Conclusions: VF rate increases over time in patients with left ventricular assist devices and is lowered by ablation. Long-lasting VF may be modified or even terminated by ablation.
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http://dx.doi.org/10.1161/CIRCEP.120.008639DOI Listing
October 2020

Body Surface Mapping of Ventricular Repolarization Heterogeneity: An Multiparameter Study.

Front Physiol 2020 13;11:933. Epub 2020 Aug 13.

Institute of Electrophysiology and Heart Modeling (IHU Liryc), Foundation Bordeaux University, Pessac-Bordeaux, France.

Background: Increased heterogeneity of ventricular repolarization is associated with life-threatening arrhythmia and sudden cardiac death (SCD). T-wave analysis through body surface potential mapping (BSPM) is a promising tool for risk stratification, but the clinical effectiveness of current electrocardiographic indices is still unclear, with limited experimental validation. This study aims to investigate performance of non-invasive state-of-the-art and novel T-wave markers for repolarization dispersion in an model.

Methods: Langendorff-perfused pig hearts ( = 7) were suspended in a human-shaped 256-electrode torso tank. Tank potentials were recorded during sinus rhythm before and after introducing repolarization inhomogeneities through local perfusion with dofetilide and/or pinacidil. Drug-induced repolarization gradients were investigated from BSPMs at different experiment phases. Dispersion of electrical recovery was quantified by duration parameters, i.e., the time interval between the peak and the offset of T-wave (T-T) and QT interval, and variability over time and electrodes was also assessed. The degree of T-wave symmetry to the peak was quantified by the ratio between the terminal and initial portions of T-wave area (). Morphological variability between left and right BSPM electrodes was measured by dynamic time warping (DTW). Finally, T-wave organization was assessed by the complexity of repolarization index (CR), i.e., the amount of energy non-preserved by the dominant eigenvector computed by principal component analysis (PCA), and the error between each multilead T-wave and its 3D PCA approximation (NMSE). Body surface indices were compared with global measures of epicardial dispersion of repolarization, and with local gradients between adjacent ventricular sites.

Results: After drug intervention, both regional and global repolarization heterogeneity were significantly enhanced. On the body surface, T-T was significantly prolonged and less stable in time in all experiments, while QT interval showed higher variability across the interventions in terms of duration and spatial dispersion. The rising slope of the repolarization profile was steeper, and T-waves were more asymmetric than at baseline. Interventricular shape dissimilarity was enhanced by repolarization gradients according to DTW. Organized T-wave patterns were associated with abnormal repolarization, and they were properly described by the first principal components.

Conclusion: Repolarization heterogeneity significantly affects T-wave properties, and can be non-invasively captured by BSPM-based metrics.
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http://dx.doi.org/10.3389/fphys.2020.00933DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7438571PMC
August 2020

Impedance, power, and current in radiofrequency ablation: Insights from technical, ex vivo, and clinical studies.

J Cardiovasc Electrophysiol 2020 11 13;31(11):2836-2845. Epub 2020 Aug 13.

IHU LIRYC, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Pessac-Bordeaux, France.

Background: Radiofrequency (RF) power is routinely considered during RF application. In contrast, impedance has been relatively poorly studied, despite also influencing RF lesion creation. The aim of this study was to examine the influence of electric impedance on RF lesion characteristics and on clinical RF ablation parameters.

Methods And Results: In the first part of the study, power and impedance were systematically varied and the resulting current was calculated using custom-made software. In the second part of the study, ablation lesions (n = 40) were analyzed in a porcine ex vivo model. RF applications were delivered in cardiac muscle preparations with systematically varied values of electric impedance using a contact force ablation catheter. In the third part of the study, n = 3378 clinical RF applications were analyzed, power, impedance, and current data were exported and correlated with clinical patient data. 20 ± 3 W/80 Ω, 30 ± 3 W/120 Ω, 40 ± 3 W/160 Ω, and 50 ± 3 W/200 Ω RF applications resulted in 498 ± 40, 499 ± 26, 500 ± 20, and 500 ± 16 mA RF current, which were not significantly different (p = .32). Ablation lesions were significantly different in depth and diameter when applied with the same power but different impedances (p < .01); lesion sizes decreased when increasing impedance. In clinical data, a large range of delivered current (e.g., 39-40 W: 530-754 mA) was measured, due to variations in impedance.

Conclusions: RF lesion creation is determined by current rather than by power. During clinical RF ablation procedures, impedance significantly influences current delivery and varies considerably between patients. Impedance and current are clinically relevant parameters that should be considered during RF ablation.
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http://dx.doi.org/10.1111/jce.14709DOI Listing
November 2020