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Impact of Septal Radiofrequency Ventricular Tachycardia Ablation Insights From Magnetic Resonance Imaging
Abstract
We present the case of a 38-year-old woman with no past medical history and structurally normal heart with recurrent drug-refractory septal ventricular tachycardia (VT). Despite treatment with flecainide, celiprolol, and sotalol, she experienced breakthrough episodes of VT (Figure 1B). She had undergone 5 failed attempts at VT ablation. She was therefore referred for a further attempt at ablation. Cardiac multidetector computed tomography and late gadolinium enhancement (LGE) MRI were performed before VT ablation. MRI demonstrated nontransmural subendocardial LGE on either side of the septum, which corresponded to previous ablation sites (Figure 2A, Movie I in the online-only Data Supplement).
Figure 1.
Twelve-lead ECG of sinus rhythm and clinical tachycardia. A , Sinus rhythm. B , Ventricular tachycardia with left superior axis, relatively small QRS, and a transition around V3.
Figure 2.
MRI data before and after sixth ablation procedure. A , LGE images acquired on the day before the procedure show subendocardial enhancement related to a nontransmural scar from previous ablations, on both sides of the interventricular septum and on the inferior RV wall (yellow arrows). B , LGE images acquired on day 1 after the procedure show an intramural hematoma in the septum at the site of …
... 83 A number of human studies have also demonstrated that post procedure LGE-CMR is an effective imaging modality for the characterization of lesion size and extent of transmurality. 84,85 Post-ablation scar transmurality on LGE-CMR has been reported to predict VT ablation success for intramural VT substrates. 84 An example illustrating the use of post-ablation LGE-CMR to document lesion transmurality is shown in Figure 4. ...
... 84,85 Post-ablation scar transmurality on LGE-CMR has been reported to predict VT ablation success for intramural VT substrates. 84 An example illustrating the use of post-ablation LGE-CMR to document lesion transmurality is shown in Figure 4. ...
Ventricular tachycardia (VT) is a major cause of sudden cardiac death. The majority of malignant VTs occur in patients with structural heart disease. Multimodality imaging techniques play an integral role in determining the underlying etiology and prognostic significance of VT. In recent years, advances in imaging technology have enabled characterization of the structural arrhythmogenic substrate in patients with VT with increasing precision. In parallel with these advances, the role of cardiac imaging has expanded from a largely diagnostic tool to an adjunctive tool to guide interventional approaches for treatment of VT. Invasive and noninvasive imaging techniques, often used in combination, have made it possible to integrate structural and electrophysiological information during VT ablation procedures. An important area of current development is the use of noninvasive imaging techniques based on body surface electrocardiographic mapping to elucidate the mechanisms of VT. In the future, these techniques may provide a priori information on mechanisms of VT in patients undergoing interventional procedures. This review provides an overview of the role of cardiac imaging in patients with VT.
... In this context, techniques, such as selective intracoronary ethanol injection or bipolar ablation, have demonstrated promise, however, have not been widely adopted. [3][4][5][6] A promising novel technology for ablation of intramural VT circuits of foci is the retractable needle catheter technique. Several recent studies have demonstrated that the technique may be useful in patients with VT resistant to conventional ablation. ...
... 14 However to this day, the use of bipolar ablation in humans has only been evaluated in small case series with heterogeneous clinical results. 4,6,15 Preliminary results of epicardial ablation using an openchest approach are included as Data Supplement ( Figure I in the Data Supplement). The needle catheter was held manually with moderate pressure, ≈3 cm from the needle tip. ...
Background:
-VT recurrence can occur after VT ablation due to incomplete and/or non-transmural ventricular lesion formation. We sought to compare the lesions made by a novel irrigated needle catheter to conventional radiofrequency (RF) lesions.
Methods and results:
-Thirteen female sheep (4.6±0.7yrs, 54±8kg) were studied. In 7 sheep, 60s RF applications were performed using an irrigated needle catheter. In 6 sheep, conventional lesions were made using a 4mm-irrigated catheter. 1.5 T in vivo and high-density MRI (9.4Tesla) were performed on explanted hearts from animals receiving needle RF. Conventional lesion volume was calculated as (1/6)∗π∗(A∗B(2)+C∗D(2)/2). Needle lesion volume was measured as Σ(π∗r(2))/2 with a slice thickness of 1mm. The dimensions of all lesions were also measured on gross pathology. Additional histological analysis of the needle lesions was performed. 120 endocardial left ventricular ablation lesions (conventional, n=60; needle, n=60) were created. At necropsy, more lesions were found using needle vs. conventional RF (90% vs. 75%, p<0.05). Comparing needle vs. conventional RF: Lesion volume was larger (1030±362mm3 vs. 488±384mm3, p<0.001), lesion depth was increased (9.9±2.7mm vs. 5±2.4mm, p<0.001) and more transmural lesions were created (62.5% vs. 17%, p<0.01). Pericardial contrast injection was observed in 4 apical attempts using needle RF, however with no adverse effects. Steam pops occurred in 3 attempts using conventional RF.
Conclusions:
-Irrigated needle ablation is associated with more frequent, larger, deeper, and more often transmural lesions compared to conventional irrigated ablation. This technology might be of value to treat intramural or epicardial VT substrates resistant to conventional ablation.
... [3][4][5][6] An intramural focus is often challenging to ablate using conventional RF ablation, 7 and different options are or will be possible such as high-power unipolar ablation, bipolar ablation, irrigated needle ablation, or selective coronary ethanol injection. [8][9][10][11] The following case is used to illustrate a patient-tailored approach to choose between bipolar and ethanol ablation after a failed RF attempt, since needle ablation is not approved yet for human use. ...
... Less data are available for bipolar ablation in human use and mostly small case series or case reports: data of bipolar ablation performed for RVOT, septal VT, and free-wall VT are found with short-term success ratios varying from 50% to 75%. 9,11,13 In addition, the bipolar ablation technique was found to be more effective than unipolar ablation in a computational model, except in the situation of the epicardial catheter tip surrounded by air or placed over a fat tissue layer. 14 The aim of this case report was not to present ethanol ablation as a novel technique-since this technique exists since 1987, and already became a validated method-but to explain how to take a patient-tailored approach between bipolar ablation and ethanol ablation after a previous failed RF attempt on the basis of the (dis)advantages of both strategies that are listed in Table 1. ...
... It is important to note that ablation in a normal myocardium and ablation in scar show different imaging features. When ablating in healthy tissue the lesion will present as areas of late enhancement (on CT or MR), whose transmurality can be assessed to explain VT recurrence [59]. When ablating in scar tissue, prior ablation sites will rather present on late-enhanced images as dark areas within the enhanced scar (i.e., dark core within scar) [60], possibly due to microvascular dysfunction/destruction. ...
Purpose of Review
Imaging plays a crucial role in the therapy of ventricular tachycardia (VT). We offer an overview of the different methods and provide information on their use in a clinical setting.
Recent Findings
The use of imaging in VT has progressed recently. Intracardiac echography facilitates catheter navigation and the targeting of moving intracardiac structures. Integration of pre-procedural CT or MRI allows for targeting the VT substrate, with major expected impact on VT ablation efficacy and efficiency. Advances in computational modeling may further enhance the performance of imaging, giving access to pre-operative simulation of VT. These advances in non-invasive diagnosis are increasingly being coupled with non-invasive approaches for therapy delivery.
Summary
This review highlights the latest research on the use of imaging in VT procedures. Image-based strategies are progressively shifting from using images as an adjunct tool to electrophysiological techniques, to an integration of imaging as a central element of the treatment strategy.
... This may be due to the presence of CIEDs causing artifact and reducing CMR quality and/or due to the lack of standardized endpoints in VT ablation [107]. Case reports have described CMR assessment of ablation lesions, with homogenous transmural lesions considered a surrogate for successful ablation [108]. However, to date, the clinical utility of postprocedural assessment of ablation lesions has not yet been investigated [107]. ...
Ventricular tachycardia (VT) is a life-threatening arrhythmia that may be idiopathic or result from structural heart disease. Cardiac imaging is critical in the diagnostic workup and risk stratification of patients with VT. Data gained from cardiac imaging provides information on likely mechanisms and sites of origin, as well as risk of intervention. Pre-procedural imaging can be used to plan access route(s) and identify patients where post-procedural intensive care may be required. Integration of cardiac imaging into electroanatomical mapping systems during catheter ablation procedures can facilitate the optimal approach, reduce radiation dose, and may improve clinical outcomes. Intraprocedural imaging helps guide catheter position, target substrate, and identify complications early. This review summarises the contemporary imaging modalities used in patients with VT, and their uses both pre-procedurally and intra-procedurally.
... On visualise le caractère discontinu de la ligne d'ablation, avec un gap de tissu sain (flèche pointillée) entre les deux tirs efficaces (flèches pleines) (45).Plus récemment, des études réalisées en pratique clinique confirment la possibilité de visualiser les lésions de RF à l'aide des séquences de rétention tardive(46). Le caractère transmural ou non des lésions peut être affirmé, et constitue un facteur pronostic de succès des procédures d'ablation de TV(47).Dans certains centres, l'électrophysiologie cardiaque est réalisée sous IRM. Malgré les difficultés rencontrées pour mettre en place ces techniques (compatibilité IRM de tout le matériel, accès limité au patient pendant la procédure, etc.), cette combinaison apporterait un contrôle en phase aiguë des lésions tissulaires de l'ablation par RF.A l'avenir, il sera peut-être possible de visualiser en temps réel la formation de la lésion par IRM, par l'intermédiaire de la visualisation de l'oedème lors des tirs de RF. ...
Les troubles du rythme ventriculaire demeurent un problème majeur de santé publique, en particulier les tachycardies ventriculaires (TV). Celles-ci surviennent la plupart du temps dans les suites d’un infarctus du myocarde. Les ablations par radiofréquence représentent le traitement le plus efficace pour supprimer ces tachycardies. Néanmoins, les résultats à court et long terme sont encore imparfaits ouvrant la voie à des améliorations.Nous détaillons dans ce manuscrit les principes physiopathologiques de survenue de ces tachycardies ventriculaires, les principes de fonctionnement des outils diagnostics utilisés pour leur cartographie, ainsi que les principes de destruction des circuits de ces arythmies. Nous exposons les spécificités de la technique de topostimulation mise au point au CHRU de Nancy et qui permet de réaliser des cartes de TV dans des situations où les cartes d’activation habituelles ne sont pas réalisables. Cette technique pourrait également être envisagée pour l’analyse de l’efficacité des lésions d’ablation réalisées.Nous exposons enfin l’état actuel des connaissances pour déterminer le risque d’un patient asymptomatique de présenter des TV dans le futur. La stratification du risque est actuellement basée sur la fraction d’éjection ventriculaire gauche, mais la place grandissante de l’imagerie, en particulier IRM, ouvre la voie à court terme à une détermination du risque individuel. Nous exposons notre contribution à l’amélioration de l’outil IRM et aux travaux d’analyse des cicatrices d’infarctus pour prédire le risque de trouble du rythme. Les améliorations dans la prédiction du risque individuel sont une étape essentielle dans le développement d’une médecine personnalisée
... Real-time contact force monitoring and aiming at higher force-time-integral values or ablation index may lead to more transmural lesion formation. Use of bipolar radiofrequency ablation 36,37 , transcoronary alcohol ablation 38 , and needle catheter ablation 39 may be different alternatives for achieving transmural lesions, and neutralizing deep intramyocardial foci. Unfortunately, the benefit of these strategies ...
Aims
Cardiac sarcoidosis (CS) is associated with a poor prognosis. Important features of CS include heart failure, conduction abnormalities, and ventricular arrhythmias. Ventricular tachycardia (VT) is often refractory to antiarrhythmic drugs (AAD) and immunosuppression. Catheter ablation has emerged as a treatment option for recurrent VT. However, data on the efficacy and outcomes of VT ablation in this context are sparse.
Methods and results
A systematic search was performed on PubMed, EMBASE, and Cochrane database (from inception to September 2016) with included studies providing a minimum of information on CS patients undergoing VT ablation: age, gender, VT cycle length, CS diagnosis criteria, and baseline medications. Five studies reporting on 83 patients were identified. The mean age of patients was 50 ± 8 years, 53/30 (males/females) with a maximum of 56 patients receiving immunosuppressive therapy, mean ejection fraction was 39.1 ± 3.1% and 94% had an implantable cardioverter defibrillator in situ. The median number of VTs was 3 (2.6–4.9)/patient, mean cycle length of 360 ms (326–400 ms). Hundred percent of VTs received endocardial ablation, and 18% required epicardial ablation. The complication rates were 4.7–6.3%. Relapse occurred in 45 (54.2%) patients with an incidence of relapse 0.33 (95% confidence interval 0.108–0.551, P < 0.004). Employing a less stringent endpoint (i.e. freedom from arrhythmia or reduction of ventricular arrhythmia burden), 61 (88.4%) patients improved following ablation.
Conclusions
These data support the utilization of catheter ablation in selected CS cases resistant to medical treatment. However, data are derived from observational non-controlled case series, with low-methodological quality. Therefore, future well-designed, randomized controlled trials, or large-scale registries are required.
Background
Successful bipolar radiofrequency catheter ablation (RFCA) of refractory ventricular arrhythmias (VAs) has been reported. However, the efficacy, safety, and long-term outcomes of bipolar RFCA of VAs are yet to be fully determined.
Objective
To evaluate the effectiveness and safety of bipolar RFCA in treating refractory VAs during long-term follow-up.
Methods
Eighteen patients who underwent bipolar RFCA for ventricular tachycardia (VT) at 7 institutions were retrospectively investigated. Underlying heart diseases included remote myocardial infarction (3 patients, 17%) and non-ischemic cardiomyopathy (15 patients, 83%). Although unipolar RFCA was performed in all patients, either it failed to suppress VT or VT recurred. The interventricular septum, left ventricular free wall, and left ventricular summit were targeted for bipolar RFCA.
Results
Acute success (VT termination and/or non-inducibility) was achieved with bipolar RFCA in 16 patients (89%). Complications during the procedure included complete atrioventricular block (n=2) and coronary artery stenosis (n=1). One patient underwent chemical ablation after bipolar RFCA failure. At 12-month follow-up, VT reoccurred in 8 patients (44%). However, in patients with recurrence, VT burden had decreased, only 4 patients underwent re-RFCA, and only 1 out of 4 required chemical ablation. In the remaining 4 patients, re-RFCA was not required, as VT was controlled by medication or an implantable cardioverter defibrillator.
Conclusion
Bipolar RFCA is useful in the acute suppression of refractory VT. While VT recurrence rates during long-term follow-up were relatively high, we observed a significant reduction in VT burden.
Background:
Magnetic resonance (MR) thermometry allows visualization of lesion formation in real-time during cardiac radiofrequency (RF) ablation. The present study was performed to evaluate the precision of MR thermometry without RF heating in patients exhibiting cardiac arrhythmia in a clinical setting. The evaluation relied on quantification of changes in temperature measurements caused by noise and physiological motion.
Methods:
Fourteen patients referred for cardiovascular magnetic resonance imaging underwent an extra sequence to test the temperature mapping stability during free-breathing acquisition. Phase images were acquired using a multi-slice, cardiac-triggered, single-shot echo planar imaging sequence. Temperature maps were calculated and displayed in real-time while the electrocardiogram (ECG) was recorded. The precision of temperature measurement was assessed by measuring the temporal standard deviation and temporal mean of consecutive temperature maps over a period of three minutes. The cardiac cycle was analyzed from ECG recordings to quantify the impact of arrhythmia events on the precision of temperature measurement. Finally, two retrospective strategies were tested to remove acquisition dynamics related either to arrhythmia events or sudden breathing motion.
Results:
ECG synchronization allowed categorization of inter-beat intervals (RR) into distinct beat morphologies. Five patients were in stable sinus rhythm, while nine patients showed irregular RR intervals due to ectopic beats. An average temporal standard deviation of temperature of 1.6°C was observed in patients under sinus rhythm with a frame rate corresponding to the heart rate of the patient. The temporal standard deviation rose to 2.5°C in patients with arrhythmia. The retrospective rejection strategies increased the temperature precision measurement while maintaining a sufficient frame rate.
Conclusions:
Our results indicated that real-time cardiac MR thermometry shows good precision in patients under clinical conditions, even in the presence of arrhythmia. By providing real-time visualization of temperature distribution within the myocardium during RF delivery, MR thermometry could prevent insufficient or excessive heating and thus improve safety and efficacy.
Catheter ablation provides a therapeutic option for decreasing episodes of ventricular tachycardia (VT) in patients with coronary artery disease (CAD). Clinical studies show improvement with catheter ablation in reducing arrhythmia recurrence and therapy from implantable defibrillators, but not in decreasing mortality. Ablation can be an important tool for patients with electrical storm. Overall, complication rates of catheter ablation are acceptable, but recurrence rates are still significant. Advances in mapping and ablation technologies could be expected to improve the success rates and reduce the mortality.
Although catheter ablation has been successful in reducing the recurrence of ventricular tachycardia in patients with ischemic disease, outcomes in patients with nonischemic cardiomyopathy (NICM) have not met with the same results. Success is predicated on a methodical approach to diagnosis of disease type and identification of critical substrate, and the ablation strategies used. Cardiac MRI with delayed enhancement is able to identify areas of substrate involvement, particularly in situations when conventional catheter mapping is not able to do so. Radiofrequency needle, irrigated bipolar radiofrequency, and transcoronary alcohol ablation are effective and alternative techniques to endocardial and epicardial 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.
Purpose of review:
This article summarizes current understanding of the arrhythmia substrate and effect of catheter ablation for infarct-related ventricular tachycardia, focusing on recent findings.
Recent findings:
Clinical studies support the use of catheter ablation earlier in the course of ischemic disease with moderate success in reducing arrhythmia recurrence and shocks from implantable defibrillators, although mortality remains unchanged. Ablation can be lifesaving for patients presenting with electrical storm. Advanced mapping systems with image integration facilitate identification of potential substrate, and several different approaches to manage hemodynamically unstable ventricular tachycardia have emerged. Novel ablation techniques that allow deeper lesion formation are in development.
Summary:
Catheter ablation is an important therapeutic option for preventing or reducing episodes of ventricular tachycardia in patients with ischemic cardiomyopathy. Present technologies allow successful ablation in the majority of patients, even when the arrhythmia is hemodynamically unstable. Failure of the procedure is often because of anatomic challenges that will hopefully be addressed with technological progress.
Patients with ventricular tachycardia (VT) and ventricular fibrillation (VF) and no reversible cause are difficult to treat. While implantable defibrillators prolong survival, many patients remain symptomatic due to device shocks and syncope. To address this, there have been recent advances in the catheter ablation of VT and VF. For example, non-invasive imaging has improved arrhythmia substrate characterisation, 3D catheter navigation tools have facilitated mapping of arrhythmia and substrate and ablation catheters have advanced in their ability to deliver effective lesions. However, the long-term success rates of ablation for VT and VF remain modest, with nearly half of treated patients developing recurrence within 2-3 years, and this drives the ongoing innovation in the field. This review focuses on the challenges particular to ablation of life-threatening ventricular arrhythmia, and the strategies that have been recently developed to improve procedural efficacy. Patient sub-groups that illustrate the use of new strategies are described.
Substrate Mapping and AblationIntroductionCatheter ablation of ventricular tachycardia (VT) is proven effective therapy particularly in patients with frequent defibrillator shocks. However, the optimal endpoint for VT ablation has been debated and additional endpoints have been proposed. At the same time, ablation strategies aiming at homogenizing the substrate of scar-related VT have been reported.Methods and ResultsOur method to homogenize the substrate consists of local abnormal ventricular activity (LAVA) elimination. LAVA are high-frequency sharp signals that represent near-field signals of slowly conducting tissue and hence potential VT isthmuses. Pacing maneuvers are sometimes required to differentiate them from far-field signals. Delayed enhancement on cardiac MRI and/or wall thinning on multidetector computed tomography are also extremely helpful to identify the areas of interest during ablation. A strategy aiming at careful LAVA mapping, ablation, and elimination is feasible and can be achieved in about 70% of patients with scar-related VT. Complete LAVA elimination is associated with a better outcome when compared to LAVA persistence even when VT is rendered noninducible.Conclusion
This is a simple approach, with a clear endpoint and the ability to ablate in sinus rhythm. This strategy significantly benefits from high-definition imaging, mapping, and epicardial access.
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