Non-Scar-Related and Purkinje-Related Ventricular Tachycardia in Patients With Structural Heart Disease: Prevalence, Mapping Features, and Clinical Outcomes.

OBJECTIVES: This study sought to evaluate the prevalence, mapping features, and ablation outcomes of non-scar-related ventricular tachycardia (NonScar-VT) and Purkinje-related VT (Purkinje-VT) in patients with structural heart disease. BACKGROUND: VT in structural heart disease is typically associated with scar-related myocardial re-entry. NonScar-VTs arising from areas of normal myocardium or Purkinje-VTs originating from the conduction system are less common. METHODS: We retrospectively analyzed 690 patients with structural heart disease who underwent VT ablation between 2013 and 2017. RESULTS: A total of 37 (5.4%) patients (16 [43%] with ischemic cardiomyopathy, 16 [43%] with nonischemic dilated cardiomyopathy, and 5 [14%] others) demonstrated NonScar/Purkinje-VTs, which represented the clinical VT in 76% of cases. Among the 37 VTs, 31 (84%) were Purkinje-VTs (28 bundle branch re-entrant VT). The remaining 6 (16%) VTs were NonScar-VTs and included 4 idiopathic outflow tract VTs. A total of 16 patients had prior history of VT ablations: empirical scar substrate modification was performed in 6 (38%) patients and residual inducibility of VT had not been assessed in 7 (44%). In all 37 patients, the NonScar/Purkinje-VT was successfully ablated. After a median follow-up of 18 months, the targeted NonScar/Purkinje-VT did not recur in any patients, and 28 (76%) of patients were free from any recurrent VT episodes. CONCLUSIONS: NonScar/Purkinje-VTs can be identified in 5.4% of patients undergoing VT ablation in the setting of structural heart disease. Careful effort to induce, characterize, and map these VTs is important because substrate-based ablation strategies would fail to eliminate these types of VT.

Empirical mode decomposition based ECG features in classifying and tracking ventricular arrhythmias.

Ventricular arrhythmias (VA) are life-threatening pathophysiological conditions that seriously impact the normal functioning of the heart. Ventricular tachycardia (VT) and ventricular fibrillation (VF) are the two well known types of VA. VF is the lethal of the VAs and could be characterized by its organizational progression over time. The success of cardiac resuscitation strongly depends on the type of VA, its evolution over time and response to therapy. Due to the time critical nature of VF, computationally efficient quantification of VAs and swift feedback are essential. This work attempted to arrive at computationally efficient and data-driven techniques based on Empirical Mode Decomposition for classifying and tracking VAs over time. The approaches are divided into two aims: (1) 'in-hospital' scenarios for characterizing the dynamics of VA episodes to assist clinicians in planning long-term therapy options, and (2) 'out-of-hospital' scenarios for providing near real-time feedback to detect/track the progression of VAs over time to assist medical personnel select/modify therapy options. Using an ECG database of 61 60-s VA segments obtained for classifying VT vs. VF and sub-classifying VF into organized VF (OVF) and disorganized VF (DVF), maximum classification accuracies of 96.7% (AUC = 0.993) and 87.2% (AUC = 0.968) were obtained for classifying VT vs. VF and OVF vs. DVF during 'in-hospital' analysis. Additionally, two near real-time approaches were presented for 'out-of-hospital' analysis where average accuracies of 71% and 73% were achieved for VT/VF and OVF/DVF classification, as well as demonstrating strong potential for monitoring VA progressions over time.

Refining the World Health Organization Definition: Predicting Autopsy-Defined Sudden Arrhythmic Deaths Among Presumed Sudden Cardiac Deaths in the POST SCD Study.

BACKGROUND: Conventional definitions of sudden cardiac death (SCD) presume cardiac cause. We studied the World Health Organization-defined SCDs autopsied in the POST SCD study (Postmortem Systematic Investigation of SCD) to determine whether premortem characteristics could identify autopsy-defined sudden arrhythmic death (SAD) among presumed SCDs. METHODS: Between January 2, 2011, and January 4, 2016, we prospectively identified all 615 World Health Organization-defined SCDs (144 witnessed) 18 to 90 years in San Francisco County for medical record review and autopsy via medical examiner surveillance. Autopsy-defined SADs had no extracardiac or acute heart failure cause of death. We used 2 nested sets of premortem predictors-an emergency medical system set and a comprehensive set adding medical record data-to develop Least Absolute Selection and Shrinkage Operator models of SAD among witnessed and unwitnessed cohorts. RESULTS: Of 615 presumed SCDs, 348 (57%) were autopsy-defined SAD. For witnessed cases, the emergency medical system model (area under the receiver operator curve 0.75 [0.67-0.82]) included presenting rhythm of ventricular tachycardia/fibrillation and pulseless electrical activity, while the comprehensive (area under the receiver operator curve 0.78 [0.70-0.84]) added depression. If only ventricular tachycardia/fibrillation witnessed cases (n=48) were classified as SAD, sensitivity was 0.46 (0.36-0.57), and specificity was 0.90 (0.79-0.97). For unwitnessed cases, the emergency medical system model (area under the receiver operator curve 0.68 [0.64-0.73]) included black race, male sex, age, and time since last seen normal, while the comprehensive (area under the receiver operator curve 0.75 [0.71-0.79]) added use of ß-blockers, antidepressants, QT-prolonging drugs, opiates, illicit drugs, and dyslipidemia. If only unwitnessed cases <1 hour (n=59) were classified as SAD, sensitivity was 0.18 (0.13-0.22) and specificity was 0.95 (0.90-0.97). CONCLUSIONS: Our models identify premortem characteristics that can better specify autopsy-defined SAD among presumed SCDs and suggest the World Health Organization definition can be improved by restricting witnessed SCDs to ventricular tachycardia/fibrillation or nonpulseless electrical activity rhythms and unwitnessed cases to <1 hour since last normal, at the cost of sensitivity.

Taquicàrdia ventricular idiopàtica infantil / Taquicardia ventricular idiopática infantil / Infantile idiopathic ventricular tachycardia

Introducció: Les arrítmies ventriculars en l'edat pediàtrica poden presentar-se des de formes asimptomàtiques amb extrasístoles ventriculars aïllades fins a formes amb taquicàrdia ventricular sostinguda amb insuficiència i aturada cardíaques. La taquicàrdia ventricular idiopàtica infantil és una de les entitats clíniques dins d'aquest grup, amb unes característiques clíniques i de pronòstic diferenciades, i amb una evolució generalment benigna. Observació clínica: Presentem dos casos clínics neonatals amb taquicàrdia ventricular idiopàtica infantil. Tots dos van debutar en forma de taquicàrdia ventricular ben tolerada hemodinàmicament, però donada la freqüència d'aparició dels episodis es va decidir iniciar tractament antiarrítmic amb propranolol i, posteriorment, flecaïnida. En tots dos casos, al cap de 24-48 hores d'introducció de la flecaïnida es va observar un canvi a ritme sinusal i desaparició dels episodis de taquicàrdia ventricular. En el seguiment posterior no van presentar nous episodis arrítmics. Comentaris: El reconeixement de les característiques clíniques i electrocardiogràfiques és essencial per fer un diagnòstic i un tractament correctes d'aquesta malaltia, així com per establir el diagnòstic diferencial amb altres taquicàrdies ventriculars que presenten un pronòstic pitjor

Introducción: Las arritmias ventriculares en la edad pediátrica pueden presentar desde formas asintomáticas clínicas con extrasístoles ventriculares aisladas hasta formas con taquicardia ventricular sostenida con insuficiencia cardíaca y paro cardíaco. La taquicardia ventricular idiopática infantil es una de las entidades clínicas dentro de este grupo, con unas características clínicas y de pronóstico diferenciadas y con una evolución generalmente benigna. Observación clínica: Presentamos dos casos clínicos neonatales con taquicardia ventricular idiopática infantil. Ambos debutaron en forma de taquicardia ventricular bien tolerada hemodinámicamente, pero dada la frecuencia de aparición de los episodios se decidió iniciar tratamiento antiarrítmico con propranolol y posteriormente flecainida. En ambos casos, a las 24-48 horas de introducción de la flecainida se observa paso a ritmo sinusal y desaparición de los episodios de taquicardia ventricular. En el seguimiento posterior no se observa reaparición de episodios arrítmicos. Comentarios: El reconocimiento de las características clínicas y electrocardiográficas es esencial para la correcta valoración y tratamiento de esta enfermedad, así como para el diagnóstico diferencial con otras taquicardias ventriculares que presentan un peor pronóstico

Introduction: Ventricular arrhythmias in children can present in a wide range of clinical manifestations, varying from patients that are completely asymptomatic with isolated ventricular ectopic beats to more severe forms with sustained ventricular tachycardia, heart failure and cardiac arrest. Infantile idiopathic ventricular tachycardia is one of the clinical entities within this group with different clinical characteristics and prognosis and with a generally benign evolution. Clinical observation: We present two cases of neonatal presentation of infantile idiopathic ventricular tachycardia. Both cases presented in the form of hemodynamically tolerated ventricular tachycardia, but given the frequency of occurrence of the episodes a decision was made to initiate antiarrhythmic treatment with propranolol and subsequently flecainide. In both cases, sinus rhythm and disappearance of episodes of ventricular tachycardia were documented at 24-48 hours of introduction of flecainide. Both patients had a complete resolution, with no recurrence of arrhythmic episodes on subsequent follow-up. Comments: The prompt recognition of the clinical and electrocardiographic characteristics is essential for the correct assessment and treatment of this disease, as well as for the differential diagnosis with other ventricular tachycardias that carry a worse prognosis

Device-measured physical activity data for classification of patients with ventricular arrhythmia events: A pilot investigation.

Low levels of physical activity are associated with increased mortality risk, especially in cardiac patients, but most studies are based on self-report. Cardiac implantable electronic devices (CIEDs) offer an opportunity to collect data for longer periods of time. However, there is limited agreement on the best approaches for quantification of activity measures due to the time series nature of the data. We examined physical activity time series data from 235 subjects with CIEDs and at least 365 days of uninterrupted measures. Summary statistics for raw daily physical activity (minutes/day), including statistical moments (e.g., mean, standard deviation, skewness, kurtosis), time series regression coefficients, frequency domain components, and forecasted predicted values, were calculated for each individual, and used to predict occurrence of ventricular tachycardia (VT) events as recorded by the device. In unsupervised analyses using principal component analysis, we found that while certain features tended to cluster near each other, most provided a reasonable spread across activity space without a large degree of redundancy. In supervised analyses, we found several features that were associated with the outcome (P < 0.05) in univariable and multivariable approaches, but few were consistent across models. Using a machine-learning approach in which the data was split into training and testing sets, and models ranging in complexity from simple univariable logistic regression to ensemble decision trees were fit, there was no improvement in classification of risk over naïve methods for any approach. Although standard approaches identified summary features of physical activity data that were correlated with risk of VT, machine-learning approaches found that none of these features provided an improvement in classification. Future studies are needed to explore and validate methods for feature extraction and machine learning in classification of VT risk based on device-measured activity.

Idiopathic Ventricular Premature Contraction and Ventricular Tachycardia: Distribution of the Origin, Diagnostic Algorithm, and Catheter Ablation.

Idiopathic ventricular premature contractions (VPCs), defined as VPCs in the absence of obvious structural heart disease, are one of the common types of arrhythmia in clinical practice. They are sometimes complicated with non-sustained ventricular tachycardia (VT), and/or sustained VT with almost same QRS morphology in 12 leads ECG. Idiopathic VT (IVT) commonly occurs by focal mechanisms and the origins are distributed in a variety of sites in both ventricles. In this article, the clinical characteristics of IVT/IVPCs, the diagnostic algorithm, and how to ablate them will be reviewed.

Defining the pattern of initiation of monomorphic ventricular tachycardia using the beat-to-beat intervals recorded on implantable cardioverter defibrillators from the RAFT study: A computer-based algorithm.

Arrhythmia onset pattern may have important implications on morbidity, recurrent implantable cardioverter defibrillator (ICD) shocks, and mortality, given the proposed correlation between initiation pattern and arrhythmia mechanism. Therefore, we developed and tested a computer-based algorithm to differentiate the pattern of initiation based on the beat-to-beat intervals of the ventricular tachycardia (VT) episodes in ICD recordings from the Resynchronization-Defibrillation for Ambulatory Heart Failure Trial (RAFT). Intervals on intracardiac electrograms from ICDs were analyzed backwards starting from the marker of VT detection, comparing each interval with the average tachycardia cycle length. If the morphology of the beat initiating the VT was similar to the morphology of the VT itself, the episode was considered sudden. If the morphology of the beat initiating the VT was not similar to the morphology of the VT itself, the episode was considered non-sudden. The capability of the algorithm to classify the pattern of initiation based only on the beat-to-beat intervals allows for the classification and analysis of large datasets to further investigate the clinical importance of classifying VT initiation. If analysis of the VT initiation proves to be of clinical value, this algorithm could potentially be integrated into ICD software, which would make it easily accessible and potentially helpful in clinical decision-making.

[Ventricular arrhythmias in ion channel diseases]. / Ventrikuläre Arrhythmien bei Ionenkanalerkrankungen.

In patients with ion channel disease the predominant arrhythmias are polymorphic ventricular tachycardias (VT), torsade de pointes tachycardia and ventricular fibrillation (VF). In only extremely rare cases is very rapid monomorphic ventricular tachycardia observed. This is why implantable cardioverter-defibrillators (ICDs) should always be programmed for treatment of VF only with high detection rates to avoid inappropriate discharges. In idiopathic VF and catecholaminergic polymorphic ventricular tachycardia (CPVT), no baseline electrocardiographic abnormalities can be detected, whereas in Brugada syndrome, long QT syndrome, early repolarisation syndrome and Anderson-Tawil syndrome alterations of the baseline ECG are very important to identify patients at risk.

A novel algorithm for ventricular arrhythmia classification using a fuzzy logic approach.

In the present study, it has been shown that an unnecessary implantable cardioverter-defibrillator (ICD) shock is often delivered to patients with an ambiguous ECG rhythm in the overlap zone between ventricular tachycardia (VT) and ventricular fibrillation (VF); these shocks significantly increase mortality. Therefore, accurate classification of the arrhythmia into VT, organized VF (OVF) or disorganized VF (DVF) is crucial to assist ICDs to deliver appropriate therapy. A classification algorithm using a fuzzy logic classifier was developed for accurately classifying the arrhythmias into VT, OVF or DVF. Compared with other studies, our method aims to combine ten ECG detectors that are calculated in the time domain and the frequency domain in addition to different levels of complexity for detecting subtle structure differences between VT, OVF and DVF. The classification in the overlap zone between VT and VF is refined by this study to avoid ambiguous identification. The present method was trained and tested using public ECG signal databases. A two-level classification was performed to first detect VT with an accuracy of 92.6 %, and then the discrimination between OVF and DVF was detected with an accuracy of 84.5 %. The validation results indicate that the proposed method has superior performance in identifying the organization level between the three types of arrhythmias (VT, OVF and DVF) and is promising for improving the appropriate therapy choice and decreasing the possibility of sudden cardiac death.

New Family With Catecholaminergic Polymorphic Ventricular Tachycardia Linked to the Triadin Gene.

We describe a new family with cathecholaminergic polymorphic ventricular tachycardia (CPVT) linked to the Triadin gene. This is the second report of such a CPVT of autosomal recessive inheritance. Using an NGS panel including 42 genes involved in cardiac sudden death, 2 heterozygous pathogenic mutations (c.613C> T/p.Gln205* and c.22 + 29 A>G) were identified in the Triadin gene in 2 sibs who experienced early severe arrhythmias without evidence of CPVT diagnosis at first cardiac evaluation. However, significant arrhythmias occurred after catecholaminergic stimulation. Each of the TRDN mutations was inherited from a healthy parent. In this family, genetic studies permit confirmation of the CPVT diagnosis in the 2 affected sibs and permit the early diagnosis of the third asymptomatic child. It also helped guide the therapeutic strategy in this family.

Atypical variants of right ventricular outflow arrhythmias.

BACKGROUND: Right ventricular outflow tract (RVOT) arrhythmias are a common form of ventricular tachycardia (VT) in patients with structurally normal heart. The underlying mechanism is due to triggered activity. Mapping and ablation is relatively straightforward targeting the earliest point of activation. Previously reported causes of difficult ablation in the RVOT region include under recognized right ventricular cardiomyopathy/sarcoidosis, presence of endocavitary structures, close proximity to the coronary vasculature, and origin from non-RVOT structures. METHODS AND RESULTS: We identified all patients undergoing PVCs/sustained RVOT VT ablation from January 2013 to December 2013. This included 33 patients. Of these, we identified procedures that were considered difficult despite a single morphology arrhythmia being targeted and no underlying cardiomyopathy present. Difficulty was specifically considered when ablation at the earliest site of activation was not successful and eventual successful ablation was at a distance of greater than 15 mm from the early activation site. We identified 3 patients (n = 3, 100% male) with evidence of reentrant arrhythmia based on slow conduction zones necessary for the tachycardia/arrhythmia, mid diastolic signals during VT or preceding bigeminal PVCs, pace mapping from the site abnormal signals reproducing the arrhythmia morphology but with prominent conduction delay, the entire cycle length of the tachycardia or coupling interval for the PVCs being mapping, or based on reset characteristics. CONCLUSION: In patients with atypical forms of RVOT VT, careful mapping and ablation of the myocardial sleeves near the pulmonic valve can eliminate the arrhythmia.

A classification scheme for ventricular arrhythmias using wavelets analysis.

Identification and classification of ventricular arrhythmias such as rhythmic ventricular tachycardia (VT) and disorganized ventricular fibrillation (VF) are vital tasks in guiding implantable devices to deliver appropriate therapy in preventing sudden cardiac deaths. Recent studies have shown VF can exhibit strong regional organizations, which makes the overlap zone between the fast paced rhythmic VT and VF even more ambiguous. Considering that implantable cardioverter-defibrillator (ICD) are primarily rate dependent detectors of arrhythmias and that there may be patients who suffer from arrhythmias that fall in the overlap zone, it is essential to identify the degree of affinity of the arrhythmia toward VT or organized/disorganized VF. The method proposed in this work better categorizes the overlap zone using Wavelet analysis of surface ECGs. Sixty-three surface ECG signal segments from the MIT-BIH database were used to classify between VT, organized VF (OVF), and disorganized VF (DVF). A two-level binary classifier was used to first extract VT with an overall accuracy of 93.7% and then the separation between OVF and DVF with an accuracy of 80.0%. The proposed approach could assist clinicians to provide optimal therapeutic solutions for patients in the overlap zone of VT and VF.

Using the surface electrocardiogram to localize the origin of idiopathic ventricular tachycardia.

The surface electrocardiogram (ECG) is a useful tool to help identify the sites of origin of ventricular tachycardia (VT). Despite such limitations as chest wall deformity and metabolic and drug effects, the analysis of the QRS morphologic patterns and vectors can discern the site of activation of myocardium. There have been described numerous reports about ECG features of idiopathic left- and right-ventricular VT. In this review, we summarized typical ECG characteristics according to the VT sites of origin based on previous reports, with anatomical considerations of the left and right ventricles, including the outflow tracts and epicardium.

Resolution of sustained narrow complex ventricular tachycardia and tachycardia-induced cardiomyopathy in a Quarter Horse following quinidine therapy.

Sustained narrow-QRS tachycardia of three months duration and left ventricular systolic dysfunction were identified in a fifteen-year-old Quarter Horse. No underlying cause for the tachyarrhythmia was found and no predisposing structural cardiac lesions were evident by echocardiography. Intravenous diltiazem and lidocaine were administered without achieving successful conversion of the arrhythmia. Oral quinidine therapy converted the tachyarrhythmia to sinus rhythm. Ventricular systolic dysfunction and chamber dilatation subsequently resolved. As with other species, echocardiographic features of dilated cardiomyopathy can be tachycardia-induced and may resolve following successful control of heart rate and rhythm.

[Right ventricular outflow tachycardia during pregnancy]. / Taquicardia ventricular del tracto de salida del ventrículo derecho durante el embarazo.

During pregnancy, there is an increase in metabolism, oxygen consumption, heart rate, stroke volume, cardiac output, blood volume and a decrease in blood pressure and peripheral resistance. Studies have shown that during this period the occurrence of cardiac arrhythmias is not uncommon. Fortunately, malignant arrhythmias are rare. Herein we report two young patients who presented with symptomatic right ventricular outflow tachycardia during pregnancy that required antiarrhythmic therapy. Possible pathophysiologic mechanisms are discussed.

Taquicardia ventricular del tracto de salida del ventrículo derecho durante el embarazo / Right ventricular outflow tachycardia during pregnancy

Durante el embarazo aumentan el metabolismo basal, el consumo de O2, la frecuencia cardíaca, el volumen sistólico, el volumen minuto y la volemia y disminuyen la tensión arterial y la resistencia periférica. Diferentes estudios han demostrado que durante este período la posibilidad de que ocurra una arritmia cardíaca o se produzca la exacerbación de una arritmia preexistente es mayor. No obstante, en su enorme mayoría carecen de importancia pronóstica tanto para la madre como para el feto. La taquicardia ventricular del tracto de salida del ventrículo derecho es una arritmia poco frecuente y su aparición se ha correlacionado con el aumento del tono adrenérgico. Se presentan los casos de dos pacientes que mostraron en el curso de la gestación reiterados episodios de taquicardia ventricular del tracto de salida del ventrículo derecho. Se analiza la asociación del embarazo con la ocurrencia de trastornos del ritmo cardíaco.

During pregnancy, there is an increase in metabolism, oxygen consumption, heart rate, stroke volume, cardiac output, blood volume and a decrease in blood pressure and peripheral resistance. Studies have shown that during this period the occurrence of cardiac arrhythmias is not uncommon. Fortunately, malignant arrhythmias are rare. Herein we report two young patients who presented with symptomatic right ventricular outflow tachycardia during pregnancy that required antiarrhythmic therapy. Possible pathophysiologic mechanisms are discussed.