The Year in Electrophysiology: Selected Highlights From 2023.

This special article is a continuation of an annual series for the Journal of Cardiothoracic and Vascular Anesthesia, highlighting the latest developments in the field of electrophysiology, particularly concerning cardiac anesthesiologists. The selected topics in the specialty for 2023 include consensus statements on left atrial appendage closure, outcomes in patients with atrial fibrillation and heart failure after ablation, further developments in the field of pulse field ablation, alternate defibrillation strategies for refractory ventricular fibrillation, updates on conduction system pacing, new devices such as the Aurora EV system and AVEIR leadless pacemaker system, artificial intelligence and its use in electrocardiogram-based diagnosis and latest evidence regarding the impact of anesthetic techniques on patient outcomes undergoing electrophysiology procedures.

Water-responsive supercontractile polymer films for bioelectronic interfaces.

Connecting different electronic devices is usually straightforward because they have paired, standardized interfaces, in which the shapes and sizes match each other perfectly. Tissue-electronics interfaces, however, cannot be standardized, because tissues are soft1-3 and have arbitrary shapes and sizes4-6. Shape-adaptive wrapping and covering around irregularly sized and shaped objects have been achieved using heat-shrink films because they can contract largely and rapidly when heated7. However, these materials are unsuitable for biological applications because they are usually much harder than tissues and contract at temperatures higher than 90 °C (refs. 8,9). Therefore, it is challenging to prepare stimuli-responsive films with large and rapid contractions for which the stimuli and mechanical properties are compatible with vulnerable tissues and electronic integration processes. Here, inspired by spider silk10-12, we designed water-responsive supercontractile polymer films composed of poly(ethylene oxide) and poly(ethylene glycol)-α-cyclodextrin inclusion complex, which are initially dry, flexible and stable under ambient conditions, contract by more than 50% of their original length within seconds (about 30% per second) after wetting and become soft (about 100 kPa) and stretchable (around 600%) hydrogel thin films thereafter. This supercontraction is attributed to the aligned microporous hierarchical structures of the films, which also facilitate electronic integration. We used this film to fabricate shape-adaptive electrode arrays that simplify the implantation procedure through supercontraction and conformally wrap around nerves, muscles and hearts of different sizes when wetted for in vivo nerve stimulation and electrophysiological signal recording. This study demonstrates that this water-responsive material can play an important part in shaping the next-generation tissue-electronics interfaces as well as broadening the biomedical application of shape-adaptive materials.

Oocyte activation, oolemma piercing, and real-time viability confirmation in human oocytes using electrophysiological techniques.

PURPOSE OF REVIEW: To discuss the recent applications of electrophysiological principles to the optimization and automation of the IVF laboratory. RECENT FINDINGS: There is growing evidence showing improvement of live birth rates following oocyte electro-activation. Novel applications using electrophysiological techniques are now employed to determine oocyte penetration and viability in real-time. SUMMARY: In this short review, we summarize the recent advances in the integration of electrophysiological techniques into the assisted reproductive technology laboratories. We describe the potential clinical applications and their advantages such as creation of reliable automated cell injection systems and novel manual intracytoplasmic sperm injection (ICSI) training platforms. We also discuss theoretical adverse effects and ways to mitigate them.

Advances in the automation of whole-cell patch clamp technology.

Electrophysiology is the study of neural activity in the form of local field potentials, current flow through ion channels, calcium spikes, back propagating action potentials and somatic action potentials, all measurable on a millisecond timescale. Despite great progress in imaging technologies and sensor proteins, none of the currently available tools allow imaging of neural activity on a millisecond timescale and beyond the first few hundreds of microns inside the brain. The patch clamp technique has been an invaluable tool since its inception several decades ago and has generated a wealth of knowledge about the nature of voltage- and ligand-gated ion channels, sub-threshold and supra-threshold activity, and characteristics of action potentials related to higher order functions. Many techniques that evolve to be standardized tools in the biological sciences go through a period of transformation in which they become, at least to some degree, automated, in order to improve reproducibility, throughput and standardization. The patch clamp technique is currently undergoing this transition, and in this review, we will discuss various aspects of this transition, covering advances in automated patch clamp technology both in vitro and in vivo.

Scaling Spike Detection and Sorting for Next-Generation Electrophysiology.

Reliable spike detection and sorting, the process of assigning each detected spike to its originating neuron, are essential steps in the analysis of extracellular electrical recordings from neurons. The volume and complexity of the data from recently developed large-scale, high-density microelectrode arrays and probes, which allow recording from thousands of channels simultaneously, substantially complicate this task conceptually and computationally. This chapter provides a summary and discussion of recently developed methods to tackle these challenges and discusses the important aspect of algorithm validation, and assessment of detection and sorting quality.

Driving the Next Steps with Technology.

Thinking of the progress and future of the field, neuroscientists share how advances in technology pave the way forward for understanding the brain and treating neurological disorders.

The Year in Electrophysiology: Selected Highlights From 2018.

This article is the first in an annual series for the Journal of Cardiothoracic and Vascular Anesthesia. The authors thank the editor-in-chief, Dr. Kaplan, the associate editor-in-chief, Dr. Augoustides, and the editorial board for the opportunity to start this series, namely the research highlights of the year that pertain to electrophysiology in relation to cardiothoracic and vascular anesthesia. This first article focuses on esophageal thermal injury during radiofrequency ablation, perioperative management of patients presenting for ablation procedures, left atrial appendage occlusion devices, and, finally, heart failure diagnostic devices.

Electrophysiology as a theoretical and methodological hub for the neural sciences.

Electrophysiology is a direct measure of neuronal processes, and it is uniquely sensitive to canonical neural operations that underlie emergent psychological operations. These qualities make it well suited for discovery of aberrant neural mechanisms that underlie complicated disease states. This technique is routinely utilized in vitro, in vivo, and in outpatient neurological clinics, offering a translatable bridge between animal models and human patients. The bench-to-bedside potential of this approach is unparalleled, yet it also remains undeveloped due to the slow inertia of legacy techniques and interpretations. In this review, I discuss these strengths of the method, and I detail compelling reasons why future advancements can have a direct and tangible influence over clinical practice. I hope to motivate a blurring of traditional boundaries between preclinical, computational, imaging, and clinical fields by advancing electrophysiology as a common hub for methodological integration and theoretical advancement.

Electrophysiology in the Developing World: Challenges and Opportunities.

As a subset of the growing epidemic of cardiovascular morbidity and mortality in low-income and middle-income countries (LMICs), the significant burdens of heart rhythm disorders also increase. Effective diagnostic and treatment modalities exist, but financial resources and expertise are limited. Cost-effective strategies exist to address most of these limitations, but many surmountable barriers need to be overcome to introduce and improve electrophysiologic care in LMICs. In this article, current and potential solutions are offered for the diagnostic and therapeutic challenges of managing bradyarrhythmias and tachyarrhythmias.

[Towards optical in vivo electrophysiology]. / Vers une électrophysiologie optique in vivo.

Optical imaging of voltage indicators is a promising approach for detecting the activity of neuronal circuits with high spatial and temporal resolution. In this context, genetically encoded voltage indicators, combining genetic targeting and optical readout of transmembrane voltage, represent a technological breaktrough that will without doubt have a major impact in neuroscience. However, so far the existing genetically encoded voltage indicators lacked the capabilities to detect individual action potentials and fast spike trains in live animals. Here, we present a novel indicator allowing high-fidelity imaging of individual spikes and dentritic voltage dynamics in vivo. Used in combination with optogenetics, which allows to manipulate neuronal activity, this opens the possibility of an all-optical electrophysiology.

Pediatric & Congenital Electrophysiology Society: building an international paediatric electrophysiology organisation.

The Pediatric and Congenital Electrophysiology Society (PACES) is a non-profit organisation comprised of individuals dedicated to improving the care of children and young adults with cardiac rhythm disturbances. Although PACES is a predominantly North American-centric organisation, international members have been a part of PACES for the last two decades. This year, PACES expanded its North American framework into a broadly expansive international role. On 12 May, 2015, paediatric electrophysiology leaders from within the United States of America and Canada met with over 30 international paediatric electrophysiologists from 17 countries and five continents discussing measures to (1) expand PACES' global vision, (2) address ongoing challenges such as limited resource allocation that may be present in developing countries, (3) expand PACES' governance to include international representation, (4) promote joint international sessions at future paediatric EP meetings, and (5) facilitate a global multi-centre research consortium. This meeting marked the inception of a formal international collaborative spirit in PACES. This editorial addresses some solutions to breakdown the continental silos paediatric electrophysiologists have practiced within; however, there remain ongoing limitations, and future discussions will be needed to continue to move the PACES global international vision forward.

Recent progress in multi-electrode spike sorting methods.

In recent years, arrays of extracellular electrodes have been developed and manufactured to record simultaneously from hundreds of electrodes packed with a high density. These recordings should allow neuroscientists to reconstruct the individual activity of the neurons spiking in the vicinity of these electrodes, with the help of signal processing algorithms. Algorithms need to solve a source separation problem, also known as spike sorting. However, these new devices challenge the classical way to do spike sorting. Here we review different methods that have been developed to sort spikes from these large-scale recordings. We describe the common properties of these algorithms, as well as their main differences. Finally, we outline the issues that remain to be solved by future spike sorting algorithms.

New approaches for CMOS-based devices for large-scale neural recording.

Extracellular, large scale in vivo recording of neural activity is mandatory for elucidating the interaction of neurons within large neural networks at the level of their single unit activity. Technological achievements in MEMS-based multichannel electrode arrays offer electrophysiological recording capabilities that go far beyond those of classical wire electrodes. Despite their impressive channel counts, recording systems with modest interconnection overhead have been demonstrated thanks to the hybrid integration of CMOS circuitry for signal preprocessing and data handling. The number of addressable channels is increased even further by a switch matrix for electrode selection co-integrated along the slender probe shafts. When realized by IC fabrication technologies, these probes offer highest recording site densities along the entire shaft length.

Electrophysiology of bacteria.

Bacteria secrete and harbor in their membranes a number of pore-forming proteins. Some of these are bona fide ion channels that may respond to changes in membrane tension, voltage, or pH. Others may be large translocons used for the secretion of folded or unfolded polypeptide substrates. Additionally, many secreted toxins insert into target cell membranes and form pores that either collapse membrane electrochemical gradients or provide conduits for the delivery of virulence factors. In all cases, electrophysiological approaches have yielded much progress in past decades in understanding the functional mechanisms of these pores. By monitoring the changes in current due to ion flow through the pores, these techniques are used as high-resolution tools to gather detailed information on the kinetic and permeation properties of these proteins, including those whose physiological role is not ion flux. This review highlights some of the electrophysiological studies that have advanced the field of transport by pore-forming proteins of bacterial origin.