Complexity analysis of electrical activity during endocardial and epicardial biventricular mapping of ventricular fibrillation.

Background: Ventricular fibrillation (VF) is a lethal cardiac arrhythmia that is a significant cause of sudden cardiac death. Comprehensive studies of spatiotemporal characteristics of VF in situ are difficult to perform with current mapping systems and catheter technology.

Objective: The goal of this study was to develop a computational approach to characterize VF using a commercially available technology in a large animal model.

Effects of Pulsed Electric Fields on the Coronary Arteries in Swine.

Background: Previous animal studies have shown no significant vascular injury from pulsed electrical field (PEF) ablation. We sought to assess the effect of PEF on swine coronary arteries.

Methods: We performed intracoronary and epicardial (near the coronary artery) PEF ablations in swine pretreated with dual antiplatelet and antiarrhythmic therapy.

Bipolar Electroporation Across the Interventricular Septum: Electrophysiological, Imaging, and Histopathological Characteristics.

Background: Pulsed electric field (PEF) ablation is an emerging modality for the treatment of cardiac arrhythmias. Data regarding effects on the interventricular septum are limited, and the optimal delivery protocol and electrode configuration remain undefined.

Objectives: This study sought to evaluate the electrophysiological, imaging, and histological characteristics of bipolar direct-current PEF delivered across the interventricular septum.

Open-chest Pulsed Electric Field Ablation of Cardiac Ganglionated Plexi in Acute Canine Models.

This study aimed to evaluate the safety and acute effect on markers of cardiac autonomic tone following pulsed electric fields (PEFs) delivered to epicardial ganglionated plexi (GP) during a cardiac surgical procedure. Ablation of GP as a treatment for atrial fibrillation (AF) has shown promise, but thermal ablation energy sources are limited by the risk of inadvertent collateral tissue injury. In acute canine experiments, median sternotomy was performed to facilitate the identification of 5 epicardial GP regions using an anatomy-guided approach.

Novel insights into the substrate involved in maintenance of ventricular fibrillation: results from continuous multipolar mapping in a canine model.

Background: While the triggers for ventricular fibrillation (VF) are well-known, the substrate required for its maintenance remains elusive. We have previously demonstrated dynamic spatiotemporal changes across VF from electrical induction of VF to asystole. Those data suggested that VF drivers seemed to reside in the distal RV and LV.

Ventricular nanosecond pulsed electric field delivery using active fixation leads: a proof-of-concept preclinical study.

Background: Mid-myocardial ventricular arrhythmias are challenging to treat. Cardiac electroporation via pulsed electric fields (PEFs) offers significant promise. We therefore tested PEF delivery using screw-in pacemaker leads as proof-of-concept.

Regional and Temporal Variation of Ventricular and Conduction Tissue Activity During Ventricular Fibrillation in Canines.

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Fundamentals of Cardiac Mapping.

To characterize cardiac activity and arrhythmias, electrophysiologists can record the electrical activity of the heart in relation to its anatomy through a process called cardiac mapping (electroanatomic mapping, EAM). A solid understanding of the basic cardiac biopotentials, called electrograms, is imperative to construct and interpret the cardiac EAM correctly. There are several mapping approaches available to the electrophysiologist, each optimized for specific arrhythmia mechanisms.

Anatomic Considerations Relevant to Atrial and Ventricular Arrhythmias.

Knowledge of relevant cardiac anatomy is crucial in understanding the pathophysiology and treatment of arrhythmias, and helps avoid potential complications in mapping and ablation. This article explores the anatomy, relevant to electrophysiologists, relating to atrial flutter and atrial fibrillation, ventricular tachycardia relating to the outflow tracts as well as endocardial structure, and also epicardial considerations for mapping and ablation.

Short-Term and Long-Term Outcomes of Patients Undergoing Urgent Transcatheter Aortic Valve Replacement Under a Minimalist Strategy.

Objectives: Urgent transcatheter aortic valve replacement (TAVR) is associated with worse short-term outcomes compared with elective TAVR; however, little is known about long-term outcomes or the safety of the minimalist strategy in this setting. This study investigated the short-term and long-term outcomes of urgent TAVR compared with elective TAVR under a minimalist strategy (transfemoral [TF] approach with conscious sedation and no transesophageal echocardiography guidance).

Methods: After excluding 2 emergent patients requiring immediate procedures, a total of 474 consecutive patients underwent elective TF-TAVR (396 patients; 83.

Impact of Right Ventricular Pacing in Patients Who Underwent Implantation of Permanent Pacemaker After Transcatheter Aortic Valve Implantation.

Atrioventricular conduction disturbances requiring implantation of permanent pacemaker (PPM) are a common complication following transcatheter aortic valve implantation (TAVI). Previous registry data are conflicting but suggestive of an increased risk in heart failure admissions in the post-TAVI PPM cohort. Given the expanding use of TAVI, the present study evaluates the effects of chronic right ventricular pacing (RV pacing) in post-TAVI patients.

Simultaneous Venoarterial Extracorporeal Membrane Oxygenation and Percutaneous Left Ventricular Decompression Therapy with Impella Is Associated with Improved Outcomes in Refractory Cardiogenic Shock.

Venoarterial extracorporeal membrane oxygenation (VA-ECMO) has been used for refractory cardiogenic shock; however, it is associated with increased left ventricular afterload. Outcomes associated with the combination of a percutaneous left ventricular assist device (Impella) and VA-ECMO remains largely unknown. We retrospectively reviewed patients treated for refractory cardiogenic shock with VA-ECMO (2014-2016).

Seizure reduction through interneuron-mediated entrainment using low frequency optical stimulation.

Low frequency electrical stimulation (LFS) can reduce neural excitability and suppress seizures in animals and patients with epilepsy. However the therapeutic outcome could benefit from the determination of the cell types involved in seizure suppression. We used optogenetic techniques to investigate the role of interneurons in LFS (1Hz) in the epileptogenic hippocampus.

Seizure suppression by high frequency optogenetic stimulation using in vitro and in vivo animal models of epilepsy.

Background: Electrical high frequency stimulation (HFS) has been shown to suppress seizures. However, the mechanisms of seizure suppression remain unclear and techniques for blocking specific neuronal populations are required.

Objective: The goal is to study the optical HFS protocol on seizures as well as the underlying mechanisms relevant to the HFS-mediated seizure suppression by using optogenetic methodology.

Propagation of epileptiform activity can be independent of synaptic transmission, gap junctions, or diffusion and is consistent with electrical field transmission.

The propagation of activity in neural tissue is generally associated with synaptic transmission, but epileptiform activity in the hippocampus can propagate with or without synaptic transmission at a speed of ∼0.1 m/s. This suggests an underlying common nonsynaptic mechanism for propagation.

TRPV1 antagonist capsazepine suppresses 4-AP-induced epileptiform activity in vitro and electrographic seizures in vivo.

Transient receptor potential vanilloid 1 (TRPV1) is a cation-permeable ion channel found in the peripheral and central nervous systems. The membrane surface expression of TRPV1 is known to occur in neuronal cell bodies and sensory neuron axons. TRPV1 receptors are also expressed in the hippocampus, the main epileptogenic region in the brain.

Enhanced dense core granule function and adrenal hypersecretion in a mouse model of Rett syndrome.

Rett syndrome (RTT) is a progressive developmental disorder resulting from loss-of-function mutations in the gene encoding methyl-CpG-binding protein 2 (MeCP2), a transcription regulatory protein. The RTT phenotype is complex and includes severe cardiorespiratory abnormalities, dysautonomia and behavioral symptoms of elevated stress. These findings have been attributed to an apparent hyperactivity of the sympathetic nervous system due to defects in brainstem development; however, the possibility that the peripheral sympathoadrenal axis itself is abnormal has not been explored.