Idiopathic fascicular left ventricular tachycardia: Linear ablation lesion strategy for noninducible or nonsustained tachycardia

Programmed Ventricular Stimulation: Risk Stratification and Guiding Antiarrhythmic Therapies

Electrophysiologic testing with programmed ventricular stimulation (PVS) has been utilized to induce ventricular tachycardia (VT), thereby improving risk stratification for patients with ischemic and nonischemic cardiomyopathies and determining the effectiveness of antiarrhythmic therapies, especially catheter ablation. A variety of procedural aspects can be modified during PVS in order to alter the sensitivity and specificity of the test including the addition of multiple baseline pacing cycle lengths, extrastimuli, and pacing locations. The definition of a positive result is also critically important, which has varied from exclusively sustained monomorphic VT (>30 seconds) to any ventricular arrhythmia regardless of morphology. In this review, we discuss the history of PVS and evaluate its role in sudden cardiac death risk stratification in a variety of patient populations. We propose an approach to future investigations that will capitalize on the unique ability to vary the sensitivity and specificity of this test. We then discuss the application of PVS during and following catheter ablation. The strategies that have been utilized to improve the efficacy of intraprocedural PVS are highlighted during a discussion of the limitations of this probabilistic strategy. The role of noninvasive programmed stimulation is also reviewed in predicting recurrent VT and informing management decisions including repeat ablations, modifications in antiarrhythmic drugs, and implantable cardioverter-defibrillator programming. Based on the available evidence and guidelines, we propose an approach to future investigations that will allow clinicians to optimize the use of PVS for risk stratification and assessment of therapeutic efficacy.

Upper turnaround point in a reentry circuit of the idiopathic left posterior fascicular ventricular tachycardia

BACKGROUND

The anatomic extent of the reentry circuit in idiopathic left posterior fascicular ventricular tachycardia (LPF-VT) is yet to be fully elucidated. We hypothesized that entrainment mapping could be used to delineate the reentry circuit of an LPF-VT, especially including the upper turnaround point.

METHODS

Twenty-three consecutive LPF-VT patients (mean age, 29 ± 9 years, 18 males) were included. We performed overdrive pacing with entrainment attempts at the left bundle branch (LBB) and the left His bundle (HB) region.

RESULTS

Overdrive pacing from the LBB region showed concealed fusion in all 23 patients (post-pacing interval [PPI], 322.1 ± 64.3 ms; tachycardia cycle length [TCL], 319.0 ± 61.6 ms; PPI-TCL, 3.1 ± 4.6 ms) with a long stimulus-to-QRS interval (287.9 ± 58.0 ms, approximately 90% of the TCL). Pacing from the same LBB region at a slightly faster pacing rate showed manifest fusion with antidromic conduction to the LBB and minimal in-and-out time to the LBB potential (PPI-TCL, 21.3 ± 13.7 ms). Overdrive pacing from the left HB region showed manifest fusion with a long PPI-TCL (53.9 ± 22.5 ms).

CONCLUSIONS

Our pacing study results suggest that the upper turnaround point in a reentry circuit of the LPF-VT may extend to the proximal His-Purkinje conduction system near the LBB region but below the left HB region. The LPF may constitute the retrograde limb of the reentry circuit.

Efficacy of High-Density Three-Dimensional Mapping for Verapamil-Sensitive Left Posterior Fascicular Ventricular Tachycardia in Pediatric Patients

In verapamil-sensitive left posterior fascicular ventricular tachycardia (LPF-VT), radiofrequency catheter ablation (RFA) is performed targeting mid-to-late diastolic potential (P1) and presystolic potential (P2) during tachycardia. This study included four patients who had undergone electrophysiological study (EPS) and pediatric patients with verapamil-sensitive LPF-VT who had undergone RFA using high-density three-dimensional (3D) mapping. The included patients were 11-14 years old. During EPS, right bundle branch block and superior configuration VT were induced in all patients. VT mapping was performed via the transseptal approach. P1 and P2 during VT were recorded in three of the four patients. All patients initially underwent RFA via the transseptal approach. In three patients, P1 during VT was targeted, and VT was terminated. The lesion size indices in which VT was terminated were 4.6, 4.6, and 4.7. For one patient whose P1 could not be recorded, linear ablation was performed perpendicularly in the area where P2 was recorded during VT. Among the three patients in whom VT was terminated, linear ablation was performed in two to eliminate the ventricular echo beats. In all patients, VT became uninducible in the acute phase and had not recurred 8-24 months after RFA. High-density 3D mapping with an HD Grid Mapping Catheter allows recording of P1 and P2 during VT and may improve the success rate of RFA in pediatric patients with verapamil-sensitive LPF-VT.

Comparison of strategies for catheter ablation of left posterior fascicular ventricular tachycardia

AIMS

Traditional ablation strategies including targeting the earliest Purkinje potential (PP) during left posterior fascicular (LPF) ventricular tachycardia (VT) or linear ablation at the middle segment of LPF during sinus rhythm are commonly used for the treatment of LPF-VT. Catheter ablation for LPF-VT targeting fragmented antegrade Purkinje (FAP) potential during sinus rhythm is a novel approach. We aimed to compare safety and efficacy of different ablation strategies (FAP ablation vs. traditional ablation) for the treatment of LPF-VT.

METHODS AND RESULTS

Consecutive patients with electrocardiographically documented LPF-VT referred for catheter ablation received either FAP ablation approach or traditional ablation approach. Electrophysiological characteristics, procedural complications, and long-term clinical outcome were assessed. A total of 189 consecutive patients who underwent catheter ablation for LPF-VT were included. Fragmented antegrade Purkinje ablation was attempted in 95 patients, and traditional ablation was attempted in 94 patients. Acute ablation success with elimination of LPF-VT was achieved in all patients. Left posterior fascicular block occurred in 11 of 95 (11.6%) patients in the FAP group compared with 75 of 94 (79.8%) patients in the traditional group (P < 0.001). Fragmented antegrade Purkinje ablation was associated with significant shorter procedure time (94 ± 26 vs. 117 ± 23 min, P = 0.03) and fewer radiofrequency energy applications (4.1 ± 2.4 vs. 6.3 ± 3.5, P = 0.003) compared with the traditional group. One complete atrioventricular block and one left bundle branch block were seen in the traditional group. Over mean follow-up of 65 months, 89 (93.7%) patients in the FAP group and 81 (86.2%) patients in the traditional group remained free of recurrent VT off antiarrhythmic drugs (P = 0.157).

CONCLUSION

Left posterior fascicular-ventricular tachycardia ablation utilizing FAP and traditional ablation approaches resulted in similar acute and long-term procedural outcomes. Serious His-Purkinje injury did occur infrequently during traditional ablation. The use of FAP ablation approach was associated with shorter procedure time and fewer radiofrequency energy applications, especially for non-inducible patients.

Purkinje-Related Ventricular Tachycardia and Ventricular Fibrillation: Solved and Unsolved Questions

Of the monomorphic ventricular tachycardias, there are 4 specific tachycardias related to the Purkinje system: 1) idiopathic verapamil-sensitive fascicular ventricular tachycardia (FVT); 2) non-re-entrant FVT; 3) bundle branch re-entry and interfascicular re-entry; and 4) Purkinje-mediated VT in structural heart disease. Verapamil-sensitive FVT is classified into 4 types according to the location of the circuit: 1) left posterior type; 2) left anterior type; 3) left upper septal type;and 4) reverse type. And, in the left anterior and posterior types, there are septal and papillary muscle subtypes. Although macro-re-entry has been reported to be the mechanism underlying verapamil-sensitive FVT, recording the entire circuit is challenging. One possible reason is that the Purkinje-muscle junction may penetrate the myocardial layer as a part of the circuit. The Purkinje network may thus play an important role in the initiation and maintenance of ventricular fibrillation. Further, it has been reported that the development and the abnormalities of the Purkinje system are associated with the arrhythmogenesis of ventricular fibrillation. Furthermore, it has been reported that catheter ablation of trigger ventricular premature complexes, and/or "de-networking" of the Purkinje system, can be used as electrical bailout therapy. There is a hypothesis that the intramural Purkinje system is involved in the generation of J waves. Nevertheless, as there are still unresolved issues that must be debated and accurately analyzed, this review aims to discuss the solved and unsolved questions related to Purkinje-related arrhythmias.

Fascicular Ventricular Tachycardias: Potential Role of the Septal Fascicle

Ventricular tachycardias involving the fascicular system are amongst the most challenging and intriguing arrhythmias for cardiac electrophysiologists. Although some of the more common forms have been recognized clinically for decades, other variants continue to be characterized. Moreover, considerable uncertainty persists to date with regards to the mechanisms underpinning these arrhythmias. In this state-of-the-art review, we discuss the seminal historical and contemporary observations that have collectively advanced our understanding of fascicular ventricular tachycardias. From this base, we canvas the basic and clinical evidence supporting a potential role for the septal fascicular network and propose a new schema hypothesizing involvement of this fascicle. Although we focus primarily on the most common left posterior fascicular ventricular tachycardia, our discussion and proposal have mechanistic and therapeutic implications for the spectrum of fascicular arrhythmias.

Catheter ablation of idiopathic left fascicular ventricular tachycardia: Implications of false tendons for mapping and ablation

INTRODUCTION

The anatomical substrate for idiopathic left ventricular tachycardia (ILVT) remains speculative. Purkinje networks surrounding false tendons (FTs) might be involved in the reentrant circuit of ILVT. The objective was to evaluate the anatomical and electrophysiological features of false tendons FTs in relation to ILVT.

METHODS

Intracardiac echocardiography (ICE) was conducted on patients with ILVT. The relationship of the FTs with ILVT was determined using electro-anatomical mapping.

RESULTS

Electrophysiological evaluation and radiofrequency ablation were conducted in 23 consecutive patients with ILVT. FTs were identified in 19/23 cases (82.6%) with P1 potentials during VT recorded at the FT in 14 of these patients (73.7%). Three FT types were identified. In type 1, the FT attached the septum to the base of the posteromedial papillary muscle (PPM) (4/19); type 2 FTs ran between the septum and the PPM apex (3/19), while in type 3, the connection occurred between the septum and apex (11/19) or between the septum and the LV free wall (1/19). The effective ILVT ablation sites were situated at the FT-PPM (3/19) and the FT-septum (16/19) attachment sites.

CONCLUSIONS

This series demonstrates the association between Purkinje fibers and FTs during catheter ablation of ILVT and verifies that left ventricular FTs are an important substrate in this type of tachycardia.

Idiopathic Ventricular Tachycardia

Idiopathic ventricular tachycardia (VT) is an important cause of morbidity and less commonly, mortality in patients with structurally normal hearts. Appropriate diagnosis and management are predicated on an understanding of the mechanism, relevant cardiac anatomy, and associated ECG signatures. Catheter ablation is a viable strategy to adequately treat and potentially provide a cure in patients that are intolerant to medications or when these are ineffective. In this review, we discuss special approaches and considerations for effective and safe ablation of VT arising from the right ventricular outflow tract, left ventricular outflow tract, left ventricular fascicles, papillary muscles, and moderator band.

Electrophysiological characteristics and long-term outcome of substrate-based catheter ablation for left posterior fascicular ventricular tachycardia targeting fragmented antegrade Purkinje potentials during sinus rhythm

AIMS

The aim of this study was to investigate the electrophysiological characteristics and long-term outcome of patients undergoing substrate-based ablation of left posterior fascicular ventricular tachycardia (LPF-VT) guided by targeting of fragmented antegrade Purkinje potentials (FAPs) during sinus rhythm.

METHODS AND RESULTS

This study retrospectively analysed 50 consecutive patients referred for ablation. Substrate mapping during sinus rhythm was performed to identify the FAP that was targeted by ablation. FAPs were recorded in 48 of 50 (96%) patients during sinus rhythm. The distribution of FAPs was located at the proximal segment of posterior septal left ventricle (LV) in two (4.2%) patients, middle segment in 33 (68.8%) patients, and distal segment in 13 (27.1%) patients. In 32 of 48 (66.7%) patients, the FAP displayed a continuous multicomponent fragmented electrogram, while a fragmented, split, and uncoupled electrogram was recorded in 16 (33.3%) patients. Entrainment attempts at FAP region were performed successfully in seven patients, demonstrating concealed fusion and the critical isthmus of LPF-VT. Catheter ablation targeting at the FAPs successfully terminated the LPF-VT in all 48 patients in whom they were seen. Left posterior fascicular (LPF) block occurred in four (8%) patients after ablation. During a median follow-up period of 61.2 ± 16.8 months, 47 of 50 (94%) patients remained free from recurrent LPF-VT.

CONCLUSION

Ablation of LPF-VT targeting FAP during sinus rhythm results in excellent long-term clinical outcome. FAPs were commonly located at the middle segment of posterior septal LV. Region with FAPs during sinus rhythm was predictive of critical site for re-entry.

Impact of transesophageal electrophysiological study on midterm management of pediatric tachyarrhythmias

Background

Transesophageal electrophysiological study (TEEPS) is a minimally invasive procedure that helps in evaluating the risk of recurrence of supraventricular tachycardia based on the inducibility of the tachycardia. The purpose of this study was to evaluate the diagnostic capability, negative predictive value of noninducibility of tachycardia and safety of TEEPS among the Indian pediatric population.

Methods

It is a retrospective single-center observational study of all patients who underwent TEEPS from January 01, 2014, to December 31, 2020.

Results

Twenty-two TEEPS procedures were done in eighteen children with three children undergoing more than one procedure. The median duration of follow-up was 42.97 months (8.52-82.12 months). Out of the 22 procedures, four were conducted for acute tachycardia termination, two for tachycardia suppression assessment, and sixteen to assess tachycardia inducibility off medications. Tachycardia was noninducible in nine children and inducible in six children. Two children had clinical recurrence of tachycardia on follow-up. Out of these two children, one had noninducibility of tachycardia on TEEPS. The negative predictive value of TEEPS was 88.89% in this study. None of the children had any postprocedure complication.

Conclusions

TEEPS is a safe procedure. It is used to assess the efficacy of medication in the suppression of arrhythmia. The noninducibility of tachycardia has a high negative predictive value and is a good indicator of nonrecurrence of clinical tachycardia on midterm follow-up.

Diagnosis and Management of Complex Reentrant Arrhythmias Involving the His-Purkinje System

The His-Purkinje system is a network of bundles and fibres comprised of specialised cells that allow for coordinated, synchronous activation of the ventricles. Although the histology and physiology of the His-Purkinje system have been studied for more than a century, its role in ventricular arrhythmias has recently been discovered with the ongoing elucidation of the mechanisms leading to both benign and life-threatening arrhythmias. Studies of Purkinje-cell electrophysiology show multiple mechanisms responsible for ventricular arrhythmias, including enhanced automaticity, triggered activity and reentry. The variation in functional properties of Purkinje cells in different areas of the His-Purkinje system underlie the propensity for reentry within Purkinje fibres in structurally normal and abnormal hearts. Catheter ablation is an effective therapy in nearly all forms of reentrant arrhythmias involving Purkinje tissue. However, identifying those at risk of developing fascicular arrhythmias is not yet possible. Future research is needed to understand the precise molecular and functional changes resulting in these arrhythmias.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias: executive summary

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

Use of the inverse solution guidance algorithm method for RF ablation catheter guidance

INTRODUCTION

We previously introduced the inverse solution guidance algorithm (ISGA) methodology using a Single Equivalent Moving Dipole model of cardiac electrical activity to localize both the exit site of a re-entrant circuit and the tip of a radiofrequency (RF) ablation catheter. The purpose of this study was to investigate the use of ISGA for ablation catheter guidance in an animal model.

METHODS

Ventricular tachycardia (VT) was simulated by rapid ventricular pacing at a target site in eleven Yorkshire swine. The ablation target was established using three different techniques: a pacing lead placed into the ventricular wall at the mid-myocardial level (Type-1), an intracardiac mapping catheter (Type-2), and an RF ablation catheter placed at a random position on the endocardial surface (Type-3). In each experiment, one operator placed the catheter/pacing lead at the target location, while another used the ISGA system to manipulate the RF ablation catheter starting from a random ventricular location to locate the target.

RESULTS

The average localization error of the RF ablation catheter tip was 0.31 ± 0.08 cm. After analyzing approximately 35 cardiac cycles of simulated VT, the ISGA system's accuracy in locating the target was 0.4 cm after four catheter movements in the Type-1 experiment, 0.48 cm after six movements in the Type-2 experiment, and 0.67 cm after seven movements in the Type-3 experiment.

CONCLUSION

We demonstrated the feasibility of using the ISGA method to guide an ablation catheter to the origin of a VT focus by analyzing a few beats of body surface potentials without electro-anatomic mapping.

The change of cardiac axis deviation in catheter ablation of verapamil-sensitive idiopathic left ventricular tachycardia

BACKGROUND

The underlying mechanism of verapamil-sensitive idiopathic left ventricular tachycardia (ILVT) has been postulated to be reentrant activation in the Purkinje fiber network of the left posterior fascicle or the left anterior fascicle (LAF). However, changing of cardiac axis deviation in sinus rhythm (SR) or during ILVT after radiofrequency catheter ablation (RFCA) has been rarely analyzed.

METHODS

Of the 232 patients with sustained ILVT induced and surface electrocardiogram (ECG) in SR recorded before and after RFCA, the changes of ECG morphology in SR and during ILVT were analyzed.

RESULTS

The surface ECG in SR changed in 114 (49.1%) patients after RFCA. ILVT could still be induced in 27 (23.7%) patients. In comparison with the original ILVT, three forms of ECG morphology were observed. In eight patients, the ILVT morphology was unchanged. In the 13 patients with ILVT axis deviation conversion after ablation, the successful target was more proximal. In the six patients with ILVT morphology change but without axis deviation conversion after ablation, the successful ablation site was more distal. Among 15 patients with recurrent ILVT during follow-up, seven patients had previous axis deviation changes in SR after RFCA, the changes maintained in four patients and recovered in three patients.

CONCLUSIONS

The morphology changes on surface ECG in SR after RFCA would not be a necessary prerequisite or a good endpoint for ILVT ablation. To analyze ILVT morphology changes after ablation would help to further clarify an appropriate approach for catheter ablation of ILVT.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias: Executive summary

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

In memory of tachycardia: A wide complex tachycardia in a young male

We present a case of a 24-year-old male with palpitations and a wide complex tachycardia. Baseline electrocardiogram (ECG) after termination of tachycardia demonstrates a normal rhythm but with inferior/anterolateral T-wave inversions (TWIs). Electrophysiologic study confirmed the diagnosis of posterior fascicular ventricular tachycardia successfully terminated by anatomic ablation of the left posterior fascicle. TWIs on the patient's baseline ECG were consistent with cardiac memory.

Mapping and Ablation of Fascicular Tachycardias (Reentrant and Nonreentrant)

Fascicular ventricular tachycardia (FVT) usually involves the left fascicular system; namely the left posterior fascicle, anterior fascicle, and rarely the upper septal fascicle. It may also involve the right Purkinje arborization. This tachycardia can be seen in normal heart or in the setting of structural heart diseases. Monomorphic FVT can be reentrant or nonreentrant and verapamil-sensitive left FVT is the second most common type of idiopathic ventricular tachycardia (VT) after right ventricular outflow tract VT. This article focuses on the practical approach for both reentrant and nonreentrant FVT, explaining the mechanism, electrocardiographic features, and electrophysiologic features of FVT.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias: Executive summary

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

Management of asymptomatic arrhythmias: a European Heart Rhythm Association (EHRA) consensus document, endorsed by the Heart Failure Association (HFA), Heart Rhythm Society (HRS), Asia Pacific Heart Rhythm Society (APHRS), Cardiac Arrhythmia Society of Southern Africa (CASSA), and Latin America Heart Rhythm Society (LAHRS)

Asymptomatic arrhythmias are frequently encountered in clinical practice. Although studies specifically dedicated to these asymptomatic arrhythmias are lacking, many arrhythmias still require proper diagnostic and prognostic evaluation and treatment to avoid severe consequences, such as stroke or systemic emboli, heart failure, or sudden cardiac death. The present document reviews the evidence, where available, and attempts to reach a consensus, where evidence is insufficient or conflicting.

Catheter Ablation of Idiopathic Ventricular Arrhythmias

Ventricular arrhythmias (VA) are observed in the setting of structural heart disease. However, in a proportion of patients presenting with VT, the routine diagnostic modalities fail to demonstrate overt myocardial abnormality. These arrhythmias have been called idiopathic VAs. They consist of various subtypes that have been defined by their anatomic location of origin within the heart and/or their underlying mechanism. While the majority of patients are asymptomatic, some experience debilitating symptoms and may develop reversible ventricular dysfunction. Catheter ablation has been traditionally reserved for patients with incapacitating symptoms or progressive ventricular dysfunction. However, as many patients are young, and catheter ablation can be curative in >90% of cases with a low risk (<1%) of serious complications, it is increasingly being offered as a first-line treatment in symptomatic patients. The approach to arrhythmia mapping is guided by the 12-lead electrocardiograph (ECG) morphology of the ventricular tachycardia (VT). Use of three dimensional (3D) electroanatomic mapping systems and intra-cardiac echocardiography are helpful in localising sites for successful ablation.

New Insights on Verapamil-Sensitive Idiopathic Left Fascicular Tachycardia

Verapamil-sensitive left fascicular monomorphic ventricular tachycardia (LF-VT) was first described ~4 decades ago. Our knowledge regarding this arrhythmia is evolving continuously. The current review aims to highlight up to date aspects of this arrhythmia focusing on its ECG recognition, new considerations of the reentrant circuit, ablation targets in inducible and non-inducible patients and the approach to LF-VT with multiform morphology.

Coupling interval variability of premature ventricular contractions in patients with different underlying pathology: an insight into the arrhythmia mechanism

Purpose

Coupling interval (CI) variability of premature ventricular contractions (PVCs) is influenced by the underlying arrhythmia mechanism. The aim of this study was to compare CI variability of PVCs in different myocardial disease entities, in order to gain insight into their arrhythmia mechanism.

Methods

Sixty-four patients with four underlying pathologies were included: idiopathic (n = 16), non-ischemic dilated cardiomyopathy (NIDCM) (n = 16), familial cardiomyopathy (PLN/LMNA) (n = 16), and post-MI (n = 16)-associated PVCs. The post-MI group was included as a reference, on account of its known re-entry mechanism. On Holter registrations, the first 20 CIs of the dominant PVC morphology were measured manually after which median ΔCI and mean SD of CI/√R-R (= CI of PVC corrected for underlying heart rate) were obtained. Two observers independently measured PVC CIs on pre-selected Holter registrations in order to determine inter- and intra-observer reliability.

Results

The largest ΔCI was seen in the PLN/LMNA group (220 ms (120–295)), the lowest in the idiopathic group (120 ms (100–190)). The ΔCI in the PLN/LMNA group was significantly larger than the post-MI group (220 ms (120–295) vs 130 ms (105–155), p = 0.023). Mean SD of CI/√R-R in the PLN/LMNA group was also significantly higher than in the post-MI group (p = 0.044). Inter- and intra-observer reliability was good (ICC = 0.91 vs 0.86 and 0.96 vs 0.77, respectively).

Conclusions

Low ΔCI and SD of CI/√R-R of idiopathic and NIDCM PVCs suggest that the underlying arrhythmia mechanisms might be re-entry or triggered activity. Abnormal automaticity or modulated parasystole are unlikely mechanisms. High CI variability in PLN/LMNA patients suggests that the re-entry and triggered activity are less likely mechanisms in this group.

Electronic supplementary material

The online version of this article (10.1007/s10840-017-0309-8) contains supplementary material, which is available to authorized users.

Catheter Ablation of Ventricular Tachycardia in Structurally Normal Hearts: Indications, Strategies, and Outcomes-Part I

Catheter ablation of ventricular tachycardia (VT) is being increasingly performed; yet, there is often confusion regarding indications, outcomes, and how to identify those patient populations most likely to benefit. The management strategy differs between those with structural heart disease and those without. For the former, an implantable cardioverter-defibrillator (ICD) is typically required due to an elevated risk for sudden cardiac death, and catheter ablation can be used as adjunctive therapy to treat or prevent repetitive ICD therapies. In contrast, VT or premature ventricular contractions in the setting of a structurally normal heart carries a low risk for sudden cardiac death; accordingly, there is typically no indication for an ICD. In these patients, catheter ablation is considered for symptom management or to treat tachycardiomyopathy and is potentially curative. Here, the authors discuss the pathophysiology, mechanism, and management of VT that occurs in the setting of a structurally normal heart and the role of catheter ablation.

Change in QRS morphology as a marker of spontaneous elimination in verapamil-sensitive idiopathic left ventricular tachycardia

BACKGROUND

Verapamil-sensitive idiopathic left ventricular tachycardia (verapamil-ILVT) is thought to be due to a reentry within the LV fascicular system. Radiofrequency catheter ablation (RFCA) is effective for elimination of the VT; however, a long-term prognosis of patients with verapamil-ILVT is still unclear.

METHODS AND RESULTS

Eighty consecutive verapamil-ILVT patients (62 men, 31 ± 12 years of age, LVEF: 65 ± 4%) were enrolled. Seventy-six (95%) cases of VT involved right bundle branch block and left axis deviation. We retrospectively analyzed changes in the QRS duration (ΔQRS-d) and QRS axis (ΔQRS-axis) during follow-up and compared them with recurrence of VT. During a mean follow-up period of 10 years (2-32 years), no sudden death or heart failure occurred. Fifty-one (64%) patients underwent RFCA, and 46 (90%) of them had no VT without any medication after RFCA. The ΔQRS-d (16 ± 2 vs. 8 ± 1 ms, P = 0.24) and ΔQRS-axis (20 ± 4 vs. 4 ± 3 degrees, P = 0.23) were not different in patients with no VT (VT[-]) and those with recurrence of VT (VT[+]). However, in the remaining 29 patients without RFCA, VT was spontaneously eliminated in 16 patients. The ΔQRS-d (30 ± 6 vs. 6 ± 1 ms, P = 0.002) and ΔQRS-axis (23 ± 4 vs. 5 ± 2 degrees, P = 0.001) were significantly larger in VT(-) patients compared to VT(+) patients during follow-up.

CONCLUSIONS

Some verapamil-ILVT patients who show QRS morphology changes over the follow-up period may become free from VT without any invasive or pharmacological treatments, suggesting that further altered LV fascicular conduction might eliminate the reentry of verapamil-ILVT.

Cellular Physiology and Clinical Manifestations of Fascicular Arrhythmias in Normal Hearts

Fascicular ventricular arrhythmias represent a spectrum of ventricular tachycardias dependent on the specialized conduction system. Although they are more common in structurally abnormal hearts, there is an increasing body of literature describing their role in normal hearts. In this review, the authors present data from both basic and clinical research that explore the current understanding of idiopathic fascicular ventricular arrhythmias. Evaluation of the cellular electrophysiology of the Purkinje cells shows clear evidence of enhanced automaticity and triggered activity as potential mechanisms of arrhythmias. Perhaps more importantly, heterogeneity in conduction system velocity and refractoriness of the left ventricular conduction system in animal models are in line with clinical descriptions of re-entrant fascicular arrhythmias in humans. Further advances in our understanding of the conduction system will help bridge the current gap between basic science and clinical fascicular arrhythmias.

Noninvasive clues for diagnosing ventricular tachycardia mechanism

The electrophysiologic mechanisms responsible for the initiation and maintenance of ventricular tachycardia (VT) include enhanced automaticity, triggered activity and reentry. Differentiating between these three mechanisms can be challenging for the clinician and usually requires an invasive electrophysiology study. Establishing the underlying VT mechanism in a particular patient is helpful to define the optimal therapeutic approach, including the selection of pharmacologic agents or delineation of an ablation strategy. The purpose of this review is to provide insight into the possible VT mechanisms based on noninvasive clues from the clinical history, 12-lead electrocardiogram, tachycardia onset and termination and the response to pharmacologic manipulation.

Bidirectional Ventricular Tachycardia Due to a Mixture of Focal Fascicular Firing and Reentry

Bidirectional ventricular tachycardia (BDVT) is a well-known phenomenon since it was first described in 1922. Various mechanisms have been proposed for BDVT, including digitalis toxicity, hypokalemia, Anderson-Tawil syndrome, acute myocarditis, and catecholaminergic polymorphic ventricular tachycardia. It is characterized by rapid, wide complex electrocardiogram pattern with alternating QRS morphology and axis. The alternation of the QRS is usually right bundle branch block with 180° swings in the frontal plane axis or, less commonly, alternation of right bundle branch and left bundle branch forms. Most of the proposed mechanisms involve triggered activity or enhanced automaticity. We describe a unique BDVT, with characteristics of both re-entry and triggered activity, which terminated with a focal Rf lesion.

Spectrum of Fascicular Arrhythmias

Fascicular arrhythmias encompass a wide spectrum of ventricular arrhythmias that depend on the specialized conduction system of the right and left ventricles. These arrhythmias include premature ventricular complexes, monomorphic ventricular tachycardia, polymorphic ventricular tachycardia, and ventricular fibrillation. These arrhythmias may be organized by mechanism, including intrafascicular reentry, interfascicular reentry, and focal. Mapping and ablation of the fascicular system can result in high cure rates of debilitating and potentially life-threatening arrhythmias. When approaching these arrhythmias, careful consideration of the structure of the His Purkinje system as well as their electrophysiologic properties may help guide even the most complex of arrhythmias.

Sustained Ventricular Tachycardia in Apparently Normal Hearts: Medical Therapy Should be the First Step in Management

Sustained monomorphic ventricular tachycardia or repetitive premature ventricular complexes can be seen in patients with structurally normal hearts. Among these types of patients, the prognosis is predominantly benign and the treatment mostly focused on elimination of symptoms rather than improving survival or reduction of mortality. This article focuses on the pharmacologic options for management and compares them with invasive options. Based on the current literature, we demonstrate that medical therapies should be used as first-line management and favored over invasive therapies. Understanding the arrhythmia mechanism is critical in choosing the appropriate medication among the wide variety of antiarrhythmic drugs available.

Mapping and ablation procedures for the treatment of ventricular tachycardia

INTRODUCTION

Ventricular tachycardia (VT) may occur in the presence or absence of structural heart disease. Given that the management of VT hinges on the presence of symptoms and risk of sudden cardiac death (SCD), the main treatment goals are elimination of symptoms (including frequent implantable cardioverter defibrillator [ICD] therapies) and prevention of SCD. Unfortunately, medical management is suboptimal in a significant proportion of patients. As such, ablative therapy plays a prominent role in the treatment of ventricular tachycardia.

AREAS COVERED

In this review, we will discuss various VT disorders that are encountered in patients with and without structural heart disease. Further, we will highlight salient features regarding mapping and ablation of the various VT syndromes. Finally, we will discuss what lies on the horizon for VT ablation. Expert commentary: Meticulous mapping should aim to find the region that is most likely to be successful and least likely to result in a complication. Although recognition of the various mechanisms of VT, familiarity with different methods to mapping and ablation, and awareness of potential limitations of current approaches is critical, a thorough understanding of the fundamental principles and nuances of each facet within EP is required to ensure optimal outcomes for our patients.