Field Of Electrophysiology Research Articles

Simulatoren und Simulatortraining in der interventionellen Elektrophysiologie

Simulators and simulator training are commonly used in many areas of industry and medicine. Simulators offer excellent training modalities for interventional cardiology to practice certain procedures and the handling of associated complications. In the field of electrophysiology, there are currently initial approaches to using simulators specifically for training purposes. A realistic simulator system does not yet exist in electrophysiology.

Cardiac magnetic resonance imaging and the myocardium : Differentiation between vital and nonvital tissue

Cardiac magnetic resonance (cMR), awell-established imaging tool, is indispensable in the diagnosis and management of cardiovascular disease. Given its high spatial resolution and ability to characterize tissue, cMR represents the gold standard in determining myocardial viability. Gadolinium-based contrast-enhanced cMR can accurately identify myocardial scars and fibrosis in the ventricle and the atria, and differentiate it from normal myocardium. Gadolinium is an extracellular molecule which has been shown to be safe and beneficial in magnetic resonance imaging (MRI). Due to the larger extracellular space in myocardial scars, there is more uptake (wash-in) and slower elimination (wash-out) of gadolinium in those areas as opposed to normal myocardium. When imaged several minutes after intravenous administration of gadolinium, nonviable myocardial areas appear brighter than viable myocardium. The use of late-gadolinium enhancement (LGE) technique in assessing myocardial viability has been shown to highly correlate with histological examinations. Furthermore, this technique is highly reproducible and has very high intra- and interobserver agreement. Extent of LGE after myocardial infarction predicts the occurrence of adverse cardiovascular events. Moreover, LGE is highly accurate in predicting functional recovery of dysfunctional myocardial segments in patients undergoing revascularization and consequently has akey role in guiding revascularization procedures. In addition, use of LGE in the identification of myocardial fibrosis or myocardial damage in inflammatory myocardial disease helps to differentiate the type of cardiomyopathy and to predict sudden cardiac death among patients with heart failure. The role of LGE-MRI in the field of electrophysiology through recognition of different substrate for arrythmias and guiding the ablation therapy is steadily increasing and has fundamentally changed our understanding of atrial myopathy.

Dedication

This issue is dedicated to our friend and colleague, Santosh Padala, MD, who died much too young. We both had the privilege of working with him over a number of years as he trained in electrophysiology and then joined the VCU faculty. Over the last seven years, his contributions to the field of electrophysiology and pacing were substantial and will far outlast his all too brief life. Each day and every patient he touched were made better by that interaction. He was a truly outstanding clinician, clinical researcher, teacher, and human being. Not only his patients but also all health care providers who came into contact with him were changed through his sheer joy and enthusiasm for learning, teaching, and healing his patients. His constant amazement and joy in everything he did continue to inspire each of us every day. He was beloved by so many, including his large extended family and friends. We hope his memory will be a source of inspiration for all.

Pulsed Field Ablation: a Novel Therapeutic Tool for Catheter-Based Treatment of Atrial Fibrillation

With catheter ablation of atrial fibrillation becoming increasingly common, the field of electrophysiology is searching for tools to improve procedural efficacy and safety. This review focuses on a novel ablation tool, pulsed field ablation, which promises to push the needle forward. Pulsed field ablation uses high-frequency electrical pulses to ablate cardiac tissue. A number of pre-clinical and clinical studies have shown pulsed field ablationoffers an efficient means of ablating cardiac tissue with minimal risk of collateral injury. Pulsed field ablation provides a non-thermal means of cardiac tissue ablation with minimal risk of injury to adjacent structures. Future studies will define the optimal current delivery, number of lesions needed to achieve the desired tissue effect, and how best to integrate pulsed field ablation catheters into 3-dimensional mapping systems.

Preliminary assessment of paediatric electrophysiology cardiac implantable electronic device resources around the world.

The Pediatric and Congenital Electrophysiology Society (PACES) is a global organisation committed to the care of children and adults with CHD and arrhythmias. To evaluate the global needs and potential inequities as it relates to cardiac implantable electronic devices. ARROW (Assessment of Rhythm Resources arOund the World) is an online survey about cardiac implantable electronic devices, sent electronically to physicians within the field of Cardiology, Pediatric Cardiology, Electrophysiology and Pediatric Electrophysiology. ARROW received 42 responders from 28 countries, 50% from low-/middle-income regions. The main differences between low-/middle- and high-income regions include availability of expertise on paediatric electrophysiology (50% versus 93%, p < 00.5) and possibility to perform invasive procedures (35% versus 93%, p < 0.005). Implant of devices in low-income areas relies significantly on patient's resources (71%). The follow-up of the devices is on the hands of paediatric cardiologist/electrophysiologist in higher resources centres (93% versus 50%, p < 0.05). The ARROW survey represents an initial assessment of the geographical characteristics in the field of Pediatric Electrophysiology. The next step is to make this "state of the art" more extensive to other aspects of the expertise. The relevance of collecting this data before the World Congress of Pediatric Cardiology and Cardiac Surgery (WCPCCS) in 2023 in Washington DC was emphasised in order to share the resulting information with the international community and set a plan of action to assist the development of arrhythmia services for children within developing regions of the world.

Performance-based risk-sharing arrangements for devices and procedures in cardiac electrophysiology: an innovative perspective.

There is an increasing pressure on demonstrating the value of medical interventions and medical technologies resulting in the proposal of new approaches for implementation in the daily practice of innovative treatments that might carry a substantial cost. While originally mainly adopted by pharmaceutical companies, in recent years medical technology companies have initiated novel value-based arrangements for using medical devices, in the form of 'outcomes-based contracts', 'performance-based contracts', or 'risk-sharing agreements'. These are all characterized by linking coverage, reimbursement, or payment for the innovative treatment to the attainment of pre-specified clinical outcomes. Risk-sharing agreements have been promoted also in the field of electrophysiology and offer the possibility to demonstrate the value of specific innovative technologies proposed in this rapidly advancing field, while relieving hospitals from taking on the whole financial risk themselves. Physicians deeply involved in the field of devices and technologies for arrhythmia management and invasive electrophysiology need to be prepared for involvement as stakeholders. This may imply engagement in the evaluation of risk-sharing agreements and specifically, in the process of assessment of technology performances or patient outcomes. Scientific Associations may have an important role in promoting the basis for value-based assessments, in promoting educational initiatives to help assess the determinants of the learning curve for innovative treatments, and in promoting large-scale registries for a precise assessment of patient outcomes and of specific technologies' performance.

Effect of Thioflavin T on the Elongation Rate of Bacteria.

The growing field of bacterial electrophysiology examines the relationship between bacterial membrane potential and cell division, growth, sporulation, and biofilm formation. These experiments require Nernstian fluorescent dyes to monitor membrane potential. Our research uses single cell imaging to determine if a common fluorescent dye, Thioflavin T (ThT), affects the growth of bacteria. We use a combination of standard growth curve measurements and single cell imaging, both brightfield and fluorescence microscopy, to monitor the growth of Bacillus subtilis and Escherichia coli as a function of ThT concentration. Increased membrane potential (hyperpolarization) leads to increased intracellular accumulation of ThT: High fluorescence intensity is an indicator of hyperpolarization. Blue light is used to hyperpolarize a subpopulation of cells to monitor cellular elongation in response to increased cellular internalization of ThT. Single cell imaging shows that the elongation rates of B. subtilis and E. coli are decreased when these cells are incubated with ThT. At micromolar concentrations of ThT, this effect may be masked in standard growth curves, but is visible with single cell measurements on agarose pads. The increased cellular accumulation of ThT is a standard measure of hyperpolarization in bacterial electrophysiology. Growth curves, a bulk measurement, are typically used to determine suitable concentrations of ThT for use in experiments. Single cell measurements show that cells incubated with ThT have decreased elongation rates. This creates a potential experimental artifact that could lead to misinterpretation of data. Hyperpolarized cells internalize more ThT. This increased intracellular concentration of ThT, rather than the change in membrane potential, could lead to decreased growth. These experiments point toward the importance of single cell measurements to detect subtle changes in cell growth. We hope this research will be useful for other researchers in their choice of dye for the detection of membrane potential.

A systematic exploration of local network state space in neocortical mouse brain slices

The ex vivo cortical slice is an extremely versatile preparation, but its utility ultimately depends on understanding its limitations and functional constraints. A question for experimentalists new to the field of cortical slice electrophysiology might be — what are the different network dynamical states available to a cortical slice as a function of excitatory drive? The purpose of this study is to provide a coherent answer to this question, within the context of extracellularly recorded population field potentials.Cortical slices (400 µm) were prepared from adult male or female C57 mice. Evoked responses were recorded within cortical layer III/IV using extracellularly positioned metal electrodes. In the first part of the study, slice excitatory drive was increased by reducing the concentration of magnesium ions in the artificial cerebrospinal fluid — and the evoked responses categorized during the transition. In the second part, each of the identified functional states were explored in greater detail with tissue perfusion conditions and excitatory drive optimised for the requisite response state.As expected, rodent cortical slices did not generate spontaneous, persistent EEG-like field potential activity. However, distinct response states (spontaneous and evoked) characterized by intermittent population bursts could be differentiated as a function of excitatory drive. Each state reflected different modes of neocortical activation: “monosynaptic” responses were brief, non-propagating activations, reflecting an inhibited cortex with sensory processing blocked; polysynaptic and epileptiform activity propagated intra-cortically, the latter reflecting a hyperactivated, hypersynchronous “seizing” cortex. Polysynaptic activity most closely resembled sensory “up states” associated with intracortical sensory processing.Understanding the functional distinction between the different cortical slice response states is the starting point for designing experiments that maximise the utility of this ex vivo model. The results and descriptions in this study should help slice experimentalists less experienced in the nuances of cortical slice neurophysiology to make informed choices about how to tailor the parameters of the model to suit the specific aims of their research.

Smoothness and continuity of cost functionals for ECG mismatch computation

The field of cardiac electrophysiology tries to abstract, describe and finally model the electrical characteristics of a heartbeat. With recent advances in cardiac electrophysiology, models have become more powerful and descriptive as ever. However, to advance to the field of inverse electrophysiological modeling, i.e. creating models from electrical measurements such as the ECG, the less investigated field of smoothness of the simulated ECGs w.r.t. model parameters need to be further explored. The present paper discusses smoothness in terms of the whole pipeline which describes how from physiological parameters, we arrive at the simulated ECG. Employing such a pipeline, we create a test-bench of a simplified idealized left ventricle model and demonstrate the most important factors for efficient inverse modeling through smooth cost functionals. Such knowledge will be important for designing and creating inverse models in future optimization and machine learning methods.

C13. Atropine Challenge: Bedside Diagnosis of Block Level

Abstract Background The concept of 2:1 AV block remains poorly understood by many physicians even after so many years of advancement in the field of electrophysiology. It cannot be classified into type I or type II second-degree AV block because there is only one PR interval to examine before the blocked P wave. Case Illustration Case 1 . A 78-year-old male with asymptomatic bradycardia was referred to our hospital. Resting ECG revealed 2:1 conduction AV block. In order to define the site of block we performed the atropine challenge test, revealed improvement of AV block to Mobitz I and then 1st degree AV block, suggesting the suprahissian block. Case 2. A 74-year-old male with inferoposterior and right ventricular STEMI was referred to our hospital. His resting ECG revealed 2:1 conduction of P wave. The atropine challenge test revealed improvement of block to 1st degree AV block, suggesting the suprahissian block. Discussion It is often difficult to distinguish intranodal and infranodal blocks when 2:1 conduction is present. Therefore, a careful search of a long ECG tracing for two consecutive P waves should be made. In addition, atropine can improve AV node conduction due to sympathetic and/or parasympatholytic stimulation. Therefore, it may increase AV node conduction but worsen infranodal block without affecting the refractory period of the infranodal. This case illustrates the importance of a noninvasive test for confirming the location of a 2:1 conduction AV block, as guide to diagnostic and therapeutic determinations.

C13. Atropine Challenge: Bedside Diagnosis of Block Level

Abstract Background The concept of 2:1 AV block remains poorly understood by many physicians even after so many years of advancement in the field of electrophysiology. It cannot be classified into type I or type II second-degree AV block because there is only one PR interval to examine before the blocked P wave. Case Illustration Case 1 . A 78-year-old male with asymptomatic bradycardia was referred to our hospital. Resting ECG revealed 2:1 conduction AV block. In order to define the site of block we performed the atropine challenge test, revealed improvement of AV block to Mobitz I and then 1st degree AV block, suggesting the suprahissian block. Case 2. A 74-year-old male with inferoposterior and right ventricular STEMI was referred to our hospital. His resting ECG revealed 2:1 conduction of P wave. The atropine challenge test revealed improvement of block to 1st degree AV block, suggesting the suprahissian block. Discussion It is often difficult to distinguish intranodal and infranodal blocks when 2:1 conduction is present. Therefore, a careful search of a long ECG tracing for two consecutive P waves should be made. In addition, atropine can improve AV node conduction due to sympathetic and/or parasympatholytic stimulation. Therefore, it may increase AV node conduction but worsen infranodal block without affecting the refractory period of the infranodal. This case illustrates the importance of a noninvasive test for confirming the location of a 2:1 conduction AV block, as guide to diagnostic and therapeutic determinations.

Artificial intelligence in the diagnosis and management of arrhythmias.

The field of cardiac electrophysiology (EP) had adopted simple artificial intelligence (AI) methodologies for decades. Recent renewed interest in deep learning techniques has opened new frontiers in electrocardiography analysis including signature identification of diseased states. Artificial intelligence advances coupled with simultaneous rapid growth in computational power, sensor technology, and availability of web-based platforms have seen the rapid growth of AI-aided applications and big data research. Changing lifestyles with an expansion of the concept of internet of things and advancements in telecommunication technology have opened doors to population-based detection of atrial fibrillation in ways, which were previously unimaginable. Artificial intelligence-aided advances in 3D cardiac imaging heralded the concept of virtual hearts and the simulation of cardiac arrhythmias. Robotics, completely non-invasive ablation therapy, and the concept of extended realities show promise to revolutionize the future of EP. In this review, we discuss the impact of AI and recent technological advances in all aspects of arrhythmia care.

Current applications of hypnosis in the field of cardiac electrophysiology

With a growing acceptance of clinical hypnosis in medicine, new fields of application are being explored. Data from recent studies support the use of hypnosis for pain management during procedures, such as ablation of arrhythmias and implantation of subcutaneous implantable cardioverter defibrillators, management of preoperative anxiety and reduction of postoperative atrial fibrillation. The aim of this review article is to summarize the findings of investigations showing the application of hypnosis in the field of cardiac electrophysiology, to review the rationale for the efficacy of hypnosis in management of cardiac arrhythmias and to highlight possible future directions in clinical applications and scientific perspectives.

Profile of Claude Desplan

“I have been in science for four decades and my enthusiasm is still as fresh as on the first day,” says Claude Desplan, the New York University (NYU) biology and neural science Silver professor, who in 2018 was elected as a member of the National Academy of Sciences. Focusing on Drosophila , among other model organisms, Desplan and his team have made significant contributions to the fields of molecular biology, genetics, developmental neurobiology, and electrophysiology. They have provided insights on body axis formation, the generation of neural diversity, the molecular mechanisms involved in retinal and optic lobe development, and the neural circuits underlying motion detection. Using evolutionary developmental biology, or “evo-devo,” approaches, they have elucidated how sensory systems in various organisms adapt to different ecological conditions. Desplan’s Inaugural Article (1) reviews his laboratory’s work on Drosophila over the past decade and describes neural development principles predicted to apply to most organisms, including mammals. Claude Desplan. Image credit: Danielle Desplan (photographer). Born in Algeria in 1953, Desplan was raised with an appreciation of multiple cultures. His mother's family settled in Algeria in the 19th century. Desplan says his mother, age 91, is one of the world’s oldest yoga instructors. Desplan’s father worked in law, as did many of his relatives, yet Desplan forged his own career path. He says, “I wanted to be a surgeon, but there was no good rationale for it.” When Desplan was 9 years old his family moved to France. There, he drew inspiration from his ninth-grade science teacher, whom he knew as Ms. Joschau. Desplan says, “Even though she was teaching geology at the time, I became interested in the natural sciences and decided to pursue a career in research.” At age 15 he met another woman who influenced his life. “I met Danielle,” says Desplan, …

The costs (and benefits) of effortful listening on context processing: A simultaneous electrophysiology, pupillometry, and behavioral study

There is an apparent disparity between the fields of cognitive audiology and cognitive electrophysiology as to how linguistic context is used when listening to perceptually challenging speech. To gain a clearer picture of how listening effort impacts context use, we conducted a pre-registered study to simultaneously examine electrophysiological, pupillometric, and behavioral responses when listening to sentences varying in contextual constraint and acoustic challenge in the same sample. Participants (N = 44) listened to sentences that were highly constraining and completed with expected or unexpected sentence-final words (“The prisoners were planning their escape/party”) or were low-constraint sentences with unexpected sentence-final words (“All day she thought about the party”). Sentences were presented either in quiet or with +3 dB SNR background noise. Pupillometry and EEG were simultaneously recorded and subsequent sentence recognition and word recall were measured. While the N400 expectancy effect was diminished by noise, suggesting impaired real-time context use, we simultaneously observed a beneficial effect of constraint on subsequent recognition memory for degraded speech. Importantly, analyses of trial-to-trial coupling between pupil dilation and N400 amplitude showed that when participants’ showed increased listening effort (i.e., greater pupil dilation), there was a subsequent recovery of the N400 effect, but at the same time, higher effort was related to poorer subsequent sentence recognition and word recall. Collectively, these findings suggest divergent effects of acoustic challenge and listening effort on context use: while noise impairs the rapid use of context to facilitate lexical semantic processing in general, this negative effect is attenuated when listeners show increased effort in response to noise. However, this effort-induced reliance on context for online word processing comes at the cost of poorer subsequent memory.

Epicardial access complications during electrophysiology procedures.

Percutaneous epicardial access (EA) was first described more than two decades ago. Since its initial introduction, indications for its utilization in the field of electrophysiology have expanded dramatically. Epicardial mapping and ablation in patients with ventricular tachycardia is routinely performed in tertiary electrophysiology centers around the world. Although limited by lack of randomized controlled trials, epicardial ablation for atrial fibrillation has been suggested as a conjunctive strategy in patients who have failed an initial endocardial catheter ablation attempt, and it is necessary for placement of some left atrial appendage occlusion devices as well. An accurate understanding of the cardiac anatomy is crucial to avoid complications such as inadvertent right ventricular puncture, injury to the coronary arteries, abdominal viscera, phrenic nerves, and esophagus during both EA and catheter ablation. The aim of this review is to provide a comprehensive overview of the cardiac anatomy, technical aspects to optimize the safety of epicardial puncture, recognize and avoid potential complications.

Bringing Microbiology to Light: Toward All-Optical Electrophysiology in Bacteria.

The observation of neuron-like behavior in bacteria, such as the occurrence of electric spiking and extended bioelectric signaling, points to the role of membrane dynamics in prokaryotes. Electrophysiology of bacteria, however, has been overlooked for long time, due to the difficulties in monitoring bacterial bioelectric phenomena with those probing techniques that are commonly used for eukaryotes. Optical technologies can allow a paradigm shift in the field of electrophysiology of bacteria, as they would permit to elicit and monitor signaling rapidly, remotely, and with high spatiotemporal precision. In this perspective, we discuss about the potentiality of light interrogation methods in microbiology, encouraging the development of all-optical electrophysiology of bacteria.

50 years of electrophysiology and cardiac pacing

During the last 50 years a continuous improvement was observed in the field of cardiac pacing and electrophysiology as for as both technological and clinical aspects were concerned. We moved from the first recording of the His bundle electrogram to the identification of the various mechanisms and sites of supraventricular and ventricular tachyarrhythmias, to three-dimensional mapping and ablation of different reentry circuits and eventually to pulmonary vein isolation for the treatment of atrial fibrillation. As far as cardiac pacing is concerned, we moved from single chamber to dual chamber pacing, to ventricular pacing and implantable automatic defibrillators provided by sophisticated diagnostic and therapeutic algorithms and by remote control. Recently a family of leadless devices (loop recorders, endocavitary pacemakers, subcutaneous defibrillators) have become available for diagnostic and therapeutic purposes and brought a significant benefit in the reduction and management of many device-related troubles.

How Convolutional Neural Network Architecture Biases Learned Opponency and Color Tuning.

Recent work suggests that changing convolutional neural network (CNN) architecture by introducing a bottleneck in the second layer can yield changes in learned function. To understand this relationship fully requires a way of quantitatively comparing trained networks. The fields of electrophysiology and psychophysics have developed a wealth of methods for characterizing visual systems that permit such comparisons. Inspired by these methods, we propose an approach to obtaining spatial and color tuning curves for convolutional neurons that can be used to classify cells in terms of their spatial and color opponency. We perform these classifications for a range of CNNs with different depths and bottleneck widths. Our key finding is that networks with a bottleneck show a strong functional organization: almost all cells in the bottleneck layer become both spatially and color opponent, and cells in the layer following the bottleneck become nonopponent. The color tuning data can further be used to form a rich understanding of how color a network encodes color. As a concrete demonstration, we show that shallower networks without a bottleneck learn a complex nonlinear color system, whereas deeper networks with tight bottlenecks learn a simple channel opponent code in the bottleneck layer. We develop a method of obtaining a hue sensitivity curve for a trained CNN that enables high-level insights that complement the low-level findings from the color tuning data. We go on to train a series of networks under different conditions to ascertain the robustness of the discussed results. Ultimately our methods and findings coalesce with prior art, strengthening our ability to interpret trained CNNs and furthering our understanding of the connection between architecture and learned representation. Trained models and code for all experiments are available at https://github.com/ecs-vlc/opponency.

Data integration for the numerical simulation of cardiac electrophysiology.

The increasing availability of extensive and accurate clinical data is rapidly shaping cardiovascular care by improving the understanding of physiological and pathological mechanisms of the cardiovascular system and opening new frontiers in designing therapies and interventions. In this direction, mathematical and numerical models provide a complementary relevant tool, able not only to reproduce patient‐specific clinical indicators but also to predict and explore unseen scenarios. With this goal, clinical data are processed and provided as inputs to the mathematical model, which quantitatively describes the physical processes that occur in the cardiac tissue. In this paper, the process of integration of clinical data and mathematical models is discussed. Some challenges and contributions in the field of cardiac electrophysiology are reported.