The use of a novel signal analysis to identify the origin of idiopathic right ventricular outflow tract ventricular tachycardia during sinus rhythm: Simultaneous amplitude frequency electrogram transformation mapping

Innovations in ventricular tachycardia ablation

Catheter ablation of ventricular arrhythmias (VAs) has evolved significantly over the past decade and is currently a well-established therapeutic option. Technological advances and improved understanding of VA mechanisms have led to tremendous innovations in VA ablation. The purpose of this review article is to provide an overview of current innovations in VA ablation. Mapping techniques, such as ultra-high density mapping, isochronal late activation mapping, and ripple mapping, have provided improved arrhythmogenic substrate delineation and potential procedural success while limiting duration of ablation procedure and potential hemodynamic compromise. Besides, more advanced mapping and ablation techniques such as epicardial and intramyocardial ablation approaches have allowed operators to more precisely target arrhythmogenic substrate. Moreover, advances in alternate energy sources, such as electroporation, as well as stereotactic radiation therapy have been proposed to be effective and safe. New catheters, such as the lattice and the saline-enhanced radiofrequency catheters, have been designed to provide deeper and more durable tissue ablation lesions compared to conventional catheters. Contact force optimization and baseline impedance modulation are important tools to optimize VT radiofrequency ablation and improve procedural success. Furthermore, advances in cardiac imaging, specifically cardiac MRI, have great potential in identifying arrhythmogenic substrate and evaluating ablation success. Overall, VA ablation has undergone significant advances over the past years. Innovations in VA mapping techniques, alternate energy source, new catheters, and utilization of cardiac imaging have great potential to improve overall procedural safety, hemodynamic stability, and procedural success.

Post-ablation augmentation of skin sympathetic nerve activity predicts a poor outcome of idiopathic ventricular arrhythmias

BACKGROUND

The neuromodulation effect after ventricular arrhythmia (VA) ablation is unclear. The study aimed to investigate skin sympathetic nerve activity (SKNA) changes in patients receiving catheter ablations for idiopathic VA.

METHODS

Of 43 patients with drug-refractory symptomatic VA receiving ablation, SKNA was continuously recorded for 10 min during resting from electrocardiogram lead I configuration and bipolar electrodes on the right arm 1 day before and 1 day after ablation.

RESULTS

Twenty-two patients with acute procedure success and no recurrence during follow-ups were classified as sustained success group (group 1). Other 21 patients were classified as failed ablation group (group 2). Baseline SKNA showed no significant difference between the two groups. Post-ablation SKNA in group 2 was significantly higher than in group 1. In patients with ablation involved right ventricular outflow tract (RVOT), the post-ablation SKNA was also significantly higher in group 2. In contrast, there was no difference in post-ablation SKNA between groups in patients receiving non-RVOT ablation.

CONCLUSION

The neuromodulation response after RVOT ablation may correspond to the sympathetic nerve distribution at RVOT. Augmentation of sympathetic activity after VA ablation indicates an unsuccessful VA suppression, especially in patients receiving ablation of RVOT VA.

Sensor, Signal, and Imaging Informatics in 2017

Objective:  To summarize significant contributions to sensor, signal, and imaging informatics literature published in 2017.

Methods:  PubMed ^® and Web of Science ^® were searched to identify the scientific publications published in 2017 that addressed sensors, signals, and imaging in medical informatics. Fifteen papers were selected by consensus as candidate best papers. Each candidate article was reviewed by section editors and at least two other external reviewers. The final selection of the four best papers was conducted by the editorial board of the International Medical Informatics Association (IMIA) Yearbook.

Results:  The selected papers of 2017 demonstrate the important scientific advances in management and analysis of sensor, signal, and imaging information.

Conclusion:  The growth of signal and imaging data and the increasing power of machine learning techniques have engendered new opportunities for research in medical informatics. This synopsis highlights cutting-edge contributions to the science of Sensor, Signal, and Imaging Informatics.

Ventricular arrhythmias in nonischemic cardiomyopathy

Nonischemic cardiomyopathies (NICMs) are composed of variable disease entities, including primary and secondary cardiomyopathies. Determining the etiology of NICM provides pivotal roles of not only the understanding of the individual pathogenesis, but also the clinical management, such as risk stratification, pharmacological treatment, and intervention therapies. Despite the diverse causes of NICM, these cases mostly require clinical attention owing to progressive myocardial injury, resulting in ventricular dysfunction and heart failure. The interaction between the diseased ventricular substrates and systemic/neurophysiological factors contributes to the cornerstones responsible for ventricular arrhythmogenesis and sudden cardiac death (SCD). Prevention of SCD and diminishing ventricular tachyarrhythmias are the important mainstays for the management of NICM patients. Given the understanding of the abnormal ventricular substrates and advancement of navigation systems, radiofrequency catheter ablation (RFCA) has become an adjunctive or alternative strategy for NICM patients who experience drug-refractory ventricular tachycardias (VTs). Successful ablation can frequently be achieved at the expense of an epicardial intervention. A recent study has proven the survival benefits for NICM patients who are free from recurrent VTs after a successful RFCA, regardless of the New York Heart Association (NYHA) functional class status or left ventricular ejection fraction. Additionally, recent evidence has highlighted the better delineation of a diseased myocardium through the incorporation of cardiovascular magnetic resonance imaging (CMRI) and 3D mapping systems, which can facilitate the identification of critical ventricular arrhythmogenic substrates in NICM patients.

Novel Mapping Strategies for Ventricular Tachycardia Ablation

Despite advances in antiarrhythmic and device therapy, ventricular tachycardia (VT) continues to be a major cause of increased morbidity and mortality. During scar-mediated monomorphic ventricular tachycardia ablation, the search for critical isthmus sites continues to be the primary goal during successful ablative procedures. However, given the overwhelming hemodynamic instability of most ventricular arrhythmias (> 70%), VT ablation is increasingly performed during sinus rhythm. This technique requires either a greater reliance on isthmus surrogates, or more extensive ablation techniques and is a more probabilistic approach to substrate modification. We believe that a better understanding of scar physiology and activation during sinus rhythm has important implications for clinical workflow and mechanistic improvements with current ablation strategies. With advancements in high-density mapping and multi-electrode catheter technology, mapping of VT substrates is performed with higher resolution, with improved visualization of local abnormal ventricular activities (LAVA), and with a more nuanced functional understanding of late potentials. As a prerequisite, our practice for VT ablation starts with a high-density structural map to identify voltage abnormalities as well as an isochronal functional map of sinus rhythm activation to identify region of discontinuous wavefront propagation. As the era of increased automation has emerged, there continues to be vast array of customizable features, and we have adopted the use of multiple wavefront mapping to further elucidate possible arrhythmogenic substrate. Our emerging understanding of how scar propagation patterns relate to areas of abnormal signals and critical isthmuses may greatly improve the ability to identify surrogates during sinus rhythm and help localize the most arrhythmogenic regions within a given scar. In the hemodynamically unstable patients, we routinely integrate isochronal late activation mapping (ILAM) to identify areas of slow conduction to initiate our targeted ablation and substrate modification. Multi-electrode delineation of the entire reentrant VT circuit has value in understanding the size of the circuit, rotational nature, and transmural extent of human reentry. Correlative studies between the activation of the complete VT circuit and sinus rhythm are likely to provide important mechanistic insights on where fixed and/or functional block occurs within a complex scar substrate.