Determination of lethal electric field threshold for pulsed field ablation in perfused porcine and human hearts.

Introduction: Pulsed field ablation is an emerging modality for catheter-based cardiac ablation. The main mechanism of action is irreversible electroporation (IRE), a threshold-based phenomenon in which cells die after exposure to intense pulsed electric fields. Lethal electric field threshold for IRE is a tissue property that determines treatment feasibility and enables the development of new devices and therapeutic applications, but it is greatly dependent on the number of pulses and their duration.

Reversible and Irreversible Effects of Electroporation on Contractility and Calcium Homeostasis in Isolated Cardiac Ventricular Myocytes.

Background: Irreversible electroporation is an energy form utilizing high-voltage pulsed electric field, leading to cellular homeostasis disruption and cell death. Recently, irreversible electroporation has shown promising results for the treatment of cardiac arrhythmias. However, reversible and irreversible effects of pulsed electric field on cardiac myocytes remain poorly understood.

Effects of Electrode-Tissue Proximity on Cardiac Lesion Formation Using Pulsed Field Ablation.

Background: Pulsed field ablation (PFA) is a novel energy modality for treatment of cardiac arrhythmias. The impact of electrode-tissue proximity on lesion formation by PFA has not been conclusively assessed. The objective of this investigation was to evaluate the effects of electrode-tissue proximity on cardiac lesion formation with a biphasic, bipolar PFA system.

Characterization of Phrenic Nerve Response to Pulsed Field Ablation.

Background: Phrenic nerve palsy is a well-known complication of cardiac ablation, resulting from the application of direct thermal energy. Emerging pulsed field ablation (PFA) may reduce the risk of phrenic nerve injury but has not been well characterized.

Methods: Accelerometers and continuous pacing were used during PFA deliveries in a porcine model.

Safety and chronic lesion characterization of pulsed field ablation in a Porcine model.

Background: Pulsed field ablation (PFA) has been identified as an alternative to thermal-based ablation systems for treatment of atrial fibrillation patients. The objective of this Good Laboratory Practice (GLP) study was to characterize the chronic effects and safety of overlapping lesions created by a PFA system at intracardiac locations in a porcine model.

Methods: A circular catheter with nine gold electrodes was used for overlapping low- or high-dose PFA deliveries in the superior vena cava (SVC), right atrial appendage (RAA), and right superior pulmonary vein (RSPV) in six pigs.

Reduction in Pulmonary Vein Stenosis and Collateral Damage With Pulsed Field Ablation Compared With Radiofrequency Ablation in a Canine Model.

Background: Pulmonary vein (PV) stenosis is a highly morbid condition that can result after catheter ablation for PV isolation. We hypothesized that pulsed field ablation (PFA) would reduce PV stenosis risk and collateral injury compared with irrigated radiofrequency ablation (IRF).

Methods: IRF and PFA deliveries were randomized in 8 dogs with 2 superior PVs ablated using one technology and 2 inferior PVs ablated using the other technology.

Intracardiac pulsed field ablation: Proof of feasibility in a chronic porcine model.

Background: Radiofrequency (RF) has become an accepted energy source for myocardial ablation but may result in discontinuous lesions and nontargeted tissue injury. We examined the feasibility and safety of lesion formation using high-amplitude, bipolar pulsed electric fields delivered from a multielectrode array catheter.

Objective: The purpose of this study was to compare duty-cycled radiofrequency ablation (RFA) to pulsed field ablation (PFA) in terms of acute electrical effects, 2-week lesion formation, and injury to nontargeted tissues.

Predictability of lesion durability for AF ablation using phased radiofrequency: Power, temperature, and duration impact creation of transmural lesions.

Background: Long-term clinical outcomes for atrial fibrillation ablation depend on the creation of durable transmural lesions during pulmonary vein isolation and on substrate modification. Focal conventional radiofrequency (RF) ablation studies have demonstrated that tissue temperature and power are important factors for lesion formation. However, the impact and predictability of temperature and power on contiguous, transmural lesion formation with a phased RF system has not been described.

Do you see what I hear? Vantage point preference and visual dominance in a time-space synaesthete.

Time-space synaesthetes "see" time units organized in a spatial form. While the structure might be invariant for most synaesthetes, the perspective by which some view their calendar is somewhat flexible. One well-studied synaesthete L adopts different viewpoints for months seen vs.

Microembolism and catheter ablation I: a comparison of irrigated radiofrequency and multielectrode-phased radiofrequency catheter ablation of pulmonary vein ostia.

Background: Cerebral diffusion-weighted MRI lesions have been observed after catheter ablation of atrial fibrillation. We hypothesized that conditions predisposing to microembolization could be identified using a porcine model of pulmonary vein ablation and an extracorporeal circulation loop.

Methods And Results: Ablations of the pulmonary veins were performed in 18 swine with echo monitoring.

Microembolism and catheter ablation II: effects of cerebral microemboli injection in a canine model.

Background: Asymptomatic cerebral lesions have been observed on diffusion weighted MRI (DWI) scans shortly after catheter ablation of atrial fibrillation, but the pathogenesis of these lesions is incompletely understood.

Methods And Results: Twelve dogs underwent selective catheterization of the internal carotid or vertebral arteries. Either a microbubbled mixture of air (1.

A power function method for estimating base flow.

Analytical base flow separation techniques are often used to determine the base flow contribution to total stream flow. Most analytical methods derive base flow from discharge records alone without using basin-specific variables other than basin area. This paper derives a power function for estimating base flow, the form being aQ(b) + cQ, an analytical method calibrated against an integrated basin variable, specific conductance, relating base flow to total discharge, and is consistent with observed mathematical behavior of dissolved solids in stream flow with varying discharge.

Evaluation of the MODFLOW-2005 Conduit Flow Process.

The recent development of the Conduit Flow Process (CFP) by the U.S. Geological Survey (USGS) provides hydrogeologic modelers with a new tool that incorporates the non-Darcian, multiporosity components of flow characteristic of karst aquifers.

Exit vs. entrance block testing for cardiac lesion assessment.

Cardiac lesions are created to act as barriers which prohibit the transmission of cardiac myocyte contractile activity from one side of the lesion to the other. Testing for conduction block is the main way to acutely confirm the effectiveness of this therapy. There are two general methods used to test for conduction block.

Cardiac ablation via electroporation.

Thermal-based ablation for the treatment of arrhythmias is known to cause issues (e.g. heat loss due to blood perfusion, mechanical damage of the tissue from excessive heat, etc.

A different outlook on time: visual and auditory month names elicit different mental vantage points for a time-space synaesthete.

Synaesthesia is a fascinating condition whereby individuals report extraordinary experiences when presented with ordinary stimuli. Here we examined an individual (L) who experiences time units (i.e.

Studying reliability using identical handheld lactate analyzers.

Accusport analyzers were used to generate lactate performance curves in an investigative laboratory activity emphasizing the importance of reliable instrumentation. Both the calibration and testing phases of the exercise provided students with a hands-on opportunity to use laboratory-grade instrumentation while allowing for meaningful connections to be made between data collection and analysis. Pairs of student teams tested individual aerobically trained participants exercising to voluntary exhaustion on a cycle ergometer.

Comprehending spoken metaphoric reference: a real-time analysis.

Speakers and writers often use metaphor to describe someone or something in a referential fashion (e.g., The creampuff didn't show up for the fight to refer to a cowardly boxer).