Biphasic Waveform Research Articles

The combined effect of transcutaneous electrical nerve stimulation and transcutaneous auricular vagus nerve stimulation on pressure and heat pain thresholds in pain-free subjects: a randomized cross-over trial

BackgroundTranscutaneous electrical nerve stimulation (TENS) is a non-invasive modality that utilizes electrical currents to modulate pain in populations with acute and chronic pain. TENS has been demonstrated to produce hypoalgesic effects in postoperative pain, fibromyalgia, knee osteoarthritis, and healthy subjects. Transcutaneous auricular vagus nerve stimulation (TaVNS) is a non-invasive modality that modulates the vagus nerve by stimulating its auricular branches. The effects of the combination of TENS and TaVNS on producing an analgesic response have not been studied. Considering that TENS and TaVNS both stimulate similar analgesic pathways but through different means of activation, we can hypothesize that a combination of both methods can produce a more pronounced analgesic response. Therefore, the objective of this study is to assess the hypoalgesic effect of a combination of TENS and TaVNS in pain-free subjects.Methods/designThe study will be a simple crossover design conducted at the University of Hartford. Subjects will be recruited from the University of Hartford population via oral communication, digital flyers, and posters on campus. Thirty participants will undergo two sessions in a crossover manner with one week in between. During one session, the participants will receive TENS with active TaVNS and the other session will be a placebo procedure (TENS with placebo TaVNS). The order of these sessions will be randomized. Importantly, the pressure pain threshold (PPT) and heat pain threshold (HPT) assessors will be blinded to the treatment category. For active TaVNS, a frequency of 25 Hz will be applied with a pulse duration of 200 µs. For placebo TaVNS, the intensity will be increased to a sensory level and then decreased to 0 mA. High-frequency TENS of 100 Hz will be applied in both sessions, with a pulse duration of 200 µsec, asymmetrical biphasic square waveform, and intensity of maximal tolerance without pain. TENS and TaVNS will be turned on for 30 min after a baseline measurement of outcomes. TENS and TaVNS will then be turned off, but the electrodes will remain on until completion of post-treatment assessment. Pressure pain threshold, heat pain threshold, blood pressure, oxygen saturation, and heart rate will be tested 4 times: Once pre-intervention, once during intervention, once immediately after the intervention, and once 15 min post-intervention. Statistical analysis of the data obtained will consider a significance level of p < 0.05.DiscussionThis study will provide evidence concerning the combined effects of TENS and TaVNS on pain threshold in pain-free participants. Based on the outcomes, a greater understanding of how TENS and TaVNS, when used in conjunction, can modulate pain pathways.Trial registrationClinicalTrials.gov NCT06361381. Registered on 09 April 2024.

Non-invasive Transcutaneous Spinal Cord Stimulation Programming Recommendations for the Treatment of Upper Extremity Impairment in Tetraplegia

ObjectivesThis study analyzes the stimulation parameters implemented during two successful trials that used non-invasive transcutaneous spinal cord stimulation (tSCS) to effectively improve upper extremity function after chronic spinal cord injury (SCI). It proposes a framework to guide stimulation programming decisions for the successful translation of these techniques into the clinic. Materials and MethodsProgramming data from 60 participants who completed the Up-LIFT trial and from 17 participants who subsequently completed the LIFT Home trial were analyzed. All observations of stimulation amplitudes, frequencies, waveforms, and electrode configurations were examined. The incidence of adverse events and relatedness to stimulation parameters is reported. A comparison of parameter usage across the American Spinal Injury Association Impairment Scale (AIS) subgroups was conducted to evaluate stimulation strategies across participants with varying degrees of sensorimotor preservation. ResultsActive (cathodal) electrodes were typically placed between the C3/C4 and C6/C7 spinous processes. Most sessions featured return (anodal) electrodes positioned bilaterally over the anterior superior iliac spine, although clavicular placement was frequently used by 12 participants. Stimulation was delivered with a 10-kHz carrier frequency and typically a 30-Hz burst frequency. Biphasic waveforms were used in 83% of sessions. Average stimulation amplitudes were higher for biphasic waveforms. The AIS B subgroup required significantly higher amplitudes than did the AIS C and D subgroups. Device-related adverse events were infrequent, and not correlated with specific waveforms or amplitudes. Within the home setting, participants maintained their current amplitudes within 1% of the preset values. The suggested stimulation programming framework dictates the following hierarchical order of parameter adjustments: current amplitude, waveform type, active/return electrode positioning, and burst frequency, guided by clinical observations as required. ConclusionsThis analysis summarizes effective stimulation parameters from the trials and provides a decision-making framework for clinical implementation of tSCS for upper extremity functional restoration after SCI. The parameters are aligned with existing literature and proved safe and well tolerated by participants.

Can Electrical Stimulation Prevent Recurrence of Keloid Scars? A Scoping Review.

Objective: Keloids represent a symptomatic, aberrant healing process that is difficult to treat with high recurrence rates spanning from 55% to 100% if treated via excision without adjuvant therapy. Electrical stimulation (ES) has demonstrated findings that suggest it could reduce the recurrence rate of keloids after resection. Therefore, the aim of this study is to conduct a scoping review to investigate ES as an adjuvant therapy for decreasing keloid recurrence after excision. Approach: A scoping review was performed using PubMed and Web of Science databases. The search strategy encompassed terms linking keloids and various aspects of electrical stimulation. Results: Our search yielded 2,229 articles, of which 115 articles were analyzed as full text and 1 article met inclusion criteria. Despite this, ES has demonstrated other evidence that suggests its utility. ES has been shown to counter keloidic features by reducing mast cell counts, shifting wound composition from M2 to M1 macrophages, promoting angiogenesis, and controlling fibroblast orientation and location. An alternating current will orient fibroblasts perpendicular to the current without unintended migration. Innovation: Our study indicates that, based on a compilation of clinical and preclinical in vitro data, the optimal scenario for ES in the role of keloid treatment is after excision with a biphasic pulsed application and square waveform. Conclusions: ES could serve as a multifaceted, adjuvant treatment after keloid excision, steering the healing process away from keloid-associated characteristics. Its cost-effectiveness means it could be adopted globally, providing a strategy to mitigate the burden of keloids irrespective of other available treatments or economic conditions.

An Efficient Pulse Circuit Design for Magnetic Stimulation with Diversified Waveforms and Adjustable Parameters.

As a noninvasive neuromodulation technique, transcranial magnetic stimulation (TMS) has important applications both in the exploration of mental disorder causes and the treatment of mental disorders. During the stimulation, the TMS system generates the intracranial time-varying induced E-field (E-field), which alters the membrane potential of neurons and subsequently exerts neural regulatory effects. The temporal waveform of the induced E-fields is directly related to the stimulation effect. To meet the needs of scientific research on diversified stimulation waveforms and flexible adjustable stimulation parameters, a novel efficient pulse magnetic stimulation circuit (the EPMS circuit) design based on asymmetric cascaded multilevel technology is proposed in this paper. Based on the transient analysis of the discharge circuit, this circuit makes it possible to convert the physical quantity (the intracranial induced E-field) that needs to be measured after magnetic stimulation into easily analyzable electrical signals (the discharge voltage at both ends of the stimulation coil in the TMS circuit). This EPMS circuit can not only realize monophasic and biphasic cosine-shaped intracranial induced E-fields, which are widely used in the market, but also realize three types of new intracranial induced E-field stimulation waveform with optional amplitude and adjustable pulse width, including monophasic near-rectangular, biphasic near-rectangular and monophasic/biphasic ladder-shaped stimulation waveform, which breaks through the limitation of the stimulation waveform of traditional TMS systems. Among the new waveforms produced by the EPMS circuit, further research was conducted on the dynamic response characteristics of neurons under the stimulation of the biphasic four-level waveform (the BFL waveform) with controllable parameters. The relationship between TMS circuit parameters (discharge voltage level and duration) and corresponding neural response characteristics (neuron membrane potential change and neuronal polarizability ratio) was explained from a microscopic perspective. Accordingly, the biological physical quantities (neuronal membrane potential) that are difficult to measure can be transformed into easily analyzable electrical signals (the discharge voltage level and duration). Results showed that compared with monophasic and biphasic cosine induced E-fields with the same energy loss, the neuron polarization ratio is decreased by 54.5% and 87.5%, respectively, under the stimulation of BFL waveform, which could effectively enhance the neuromodulation effect and improve the stimulation selectivity.

Efficacy and safety of pulsed field ablation for accessory pathways: a pilot study.

Radiofrequency ablation is used as a first-line therapy for accessory pathways (APs). However, data regarding the effects of pulsed field ablation (PFA) on APs are limited. We sought to evaluate the acute procedural and 6-month success and safety of PFA in a cohort of patients with APs. A focal contact force-sensing PFA catheter was used for patients with APs. Pulsed field ablation generator generated a bipolar and biphasic waveform (±1000 V) with a duration of 100 ms from the tip of the PFA catheter. A 100% acute procedural success was achieved in 10 conscious patients with APs (7 left anterolateral, 2 left inferolateral, and 1 right posteroseptal APs) including 6 (60%) patients after an initial application. The average total ablation time was 6.3 ± 4.9 s for 4.7 ± 1.8 ablation sites (ASs), including 3.1 ± 2.4 s at targets and 3.2 ± 2.9 s at 3.2 ± 2 bolus ASs. The mean skin-to-skin time was 59.3 ± 15.5 min, and PFA catheter dwell time was 29.4 ± 7.8 min. One patient encountered transient sinus arrest during PFA due to parasympathetic overexcitation. Sinus rhythm was restored in all patients without any significant adverse events during the short-term follow-up. Pulsed field ablation of APs was feasible, effective, and safe. Its efficiency was remarkable for its ultrarapid termination of AP conduction. Further studies are warranted to prove whether utilization of PFA with current parameters can extend to manifold AP ablation.

Procedural safety and outcome of additional left atrial posterior wall ablation using pulse field ablation for atrial fibrillation

Abstract Introduction Pulsed field ablation (PFA) has recently been shown to be comparable to radiofrequency ablation and cryoablation in terms of acute safety and outcome for pulmonary vein isolation (PVI) for atrial fibrillation (AF). Efficacy and safety of additional left atrial posterior wall ablation (LAPWA) is unknown. We hereby report safety profile and short-term success at 6 months. Methods Consecutive patients with paroxysmal or persistent atrial fibrillation who underwent PFA were included. Procedures were performed under conscious sedation or general anaesthesia, with or without intracardiac echocardiography/ pre- or post-ablation electroanatomic mapping at the operators’ discretion. Safety endpoints included all-cause death within 30 days, cardiac tamponade, stroke/ TIA, MI, diaphragmatic paralysis, AE fistula. Primary efficacy endpoint was arrhythmia recurrence after 90 days blanking period at 6 months. LAPWA was performed using 2.0 kV biphasic waveforms, 2 deliveries for each application site. The lesion set depended on the patient’s AF ablation history, LA size, and anatomy. After LA mapping post PVI (index or re-do), 2 anchor lesions per vein extending to the LAPW were deployed. A lesion set was then performed between the anchor lesions on the LAPW (upper and lower row) with the catheter in a flower configuration and the intention of 50% overlap for the neighbouring application sites at 3D EAM. Results Seventy-two (76% males) patients underwent PFA for AF, 55 (76.4%) were paroxysmal and 4 (5.6%) were redo cases. 19 (72%) underwent additional LAPWA. LAPWA was more likely performed in patients with persistent AF (57.9% vs 11.3%, p&amp;lt;0.001), require GA (p=0.043), with 100% EAM use (p=0.026). While total PFA applications was expectedly higher in the LAPWA group (65.7 ± 12.4 vs 42.9 ± 9.0, p&amp;lt;0.001), there were no significant differences in PFA dwell time in LA (44.2 ± 14.8 vs 42.3 ± 15.5min, p=0.628), procedural time (121.3 ± 43.8 vs 119.2 ± 49.4min, p=0.866) and fluoroscopic dose, AK (130 ± 107 vs 139 ± 102mGy, p=0.748). Average number of applications required for LAPW was 18 applications. LAPW isolation was acutely successful in all 19 patients on EAM. There were 6 inpatient complications of which all happened in the non-LAPWA group and unrelated to PFA. Arrhythmia recurrence was comparable at 6 months (11.1% vs 8.9%, p=1.00). Conclusion Additional LAPWA on top of PVI using PFA is safe with excellent acute isolation of posterior wall and does not increase procedural nor fluoroscopic duration. Short term outcome appears comparable and LAPWA may be useful especially in patients with persistent AF who may not be able to tolerate long procedures but will benefit from durable rhythm control.

Stimulation-Induced Seizures in Children Undergoing Stereo-EEG Evaluation.

This study reports our center's initial experience with the use of low-frequency stimulation in provoking stimulation-induced seizures (SIS) in children with drug-resistant epilepsy undergoing stereo-EEG evaluations. This retrospective study enrolled children aged 2 to 18 years with drug-resistant focal epilepsy who underwent stereo-EEG evaluation and extraoperative direct electrical cortical stimulation to elicit seizures. The low-frequency stimulation parameters consisted of biphasic square waveforms at frequency of 1 Hz, pulse width 1 millisecond, current 1 to 3 mA, and train duration of 20 seconds. Various epilepsy-related, imaging, neurophysiology, and surgery-related variables were collected and summarized. Fourteen children (mean age 13 years; 57.1% girls) were included, 10 of whom had unilateral stereo-EEG coverage. Cortical stimulation for provoking seizures was performed after a median of 5 days after electrode implantation. The median number of electrode-contacts stimulated per patient was 42. Four patients (28.6%) experienced habitual SIS (all extratemporal). The etiology in three patients was focal cortical dysplasia. Interictal high-frequency oscillations at electrode-contacts provoking SIS were observed in three cases (75%). Two of these individuals (50%) had class 1 International League Against Epilepsy seizure outcome at last follow-up, after the resection of the brain regions generating SIS. Low-frequency (1-Hz) stimulation could provoke habitual SIS in nearly one-fourth of children with focal epilepsy undergoing stereo-EEG monitoring. This study provides a limited pediatric experience with the low-frequency cortical stimulation and SIS.

A pilot clinical assessment of biphasic asymmetric pulsed field ablation catheter for pulmonary vein isolation.

https://www.chictr.org.cn/, identifier, ChiCTR2100051894.

Rotational Thromboelastometry and Clot Waveform Analysis as Point-of-Care Tests for Diagnosis of Disseminated Intravascular Coagulation in Critically Ill Children in Thailand.

This study aimed to determine the test performances of rotational thromboelastometry (ROTEM) and activated partial thromboplastin time-based clot waveform analysis (aPTT-CWA) compared with the International Society on Thrombosis and Hemostasis disseminated intravascular coagulation (ISTH-DIC) score for diagnosis of overt disseminated intravascular coagulation (ODIC) in critically ill children. Prognostic indicators of DIC complications were also evaluated. A prospective cross-sectional observational study was conducted. ROTEM and aPTT-CWA were assessed alongside standard parameters based on the ISTH-DIC score and natural anticoagulants. Both conventional and global hemostatic tests were repeated on days 3-5 for nonovert DIC. PICU of the Department of Pediatrics, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand. Infants and children who were admitted to PICU with underlying diseases predisposed to DIC, such as sepsis, malignancy, major surgery, trauma, or severe illness, were included in the study between July 1, 2021, and November 30, 2022. None. Sixty-four children were enrolled in this study. The prevalence of ODIC was 20.3%. Regarding ROTEM parameters, using EXTEM clot formation time (CFT) cutoff of greater than 102 seconds provided sensitivity and specificity of 90.9% and 80.9%, respectively, for diagnosing ODIC, with the area under the curve (AUC) of 0.86. In the case of aPTT-CWA performance, no biphasic waveform was observed, whereas both maximum coagulation acceleration (Min2) of less than 0.35%/s 2 and maximum coagulation deceleration of less than 0.25%/s 2 demonstrated identical sensitivities of 76.9% and specificities of 79.6%. Combining two global hemostatic tests significantly improved the diagnostic performance (INTEM CFT + EXTEM CFT + Min2 AUC 0.92 [95% CI, 0.80-1.00] vs. EXTEM CFT AUC 0.86 [95% CI, 0.75-0.96], p = 0.034). Bleeding was the most common consequence. In multivariable logistic regression analysis, Min2 of less than 0.36%/s 2 was an independent risk factor for bleeding complications, with an adjusted odds ratio of 15.08 (95% CI, 1.08-211.15, p = 0.044). ROTEM and aPTT-CWA were valuable diagnostic tools in critically ill children who might require point-of-care tests. Min2 showed significant clinical implications for predicting bleeding events in this population.

In vitro biocompatibility evaluation of functional electrically stimulating microelectrodes on primary glia.

Neural interfacing devices interact with the central nervous system to alleviate functional deficits arising from disease or injury. This often entails the use of invasive microelectrode implants that elicit inflammatory responses from glial cells and leads to loss of device function. Previous work focused on improving implant biocompatibility by modifying electrode composition; here, we investigated the direct effects of electrical stimulation on glial cells at the electrode interface. A high-throughput in vitro system that assesses primary glial cell response to biphasic stimulation waveforms at 0mA, 0.15mA, and 1.5mA was developed and optimized. Primary mixed glial cell cultures were generated from heterozygous CX3CR-1+/EGFP mice, electrically stimulated for 4h/day over 3days using 75μm platinum-iridium microelectrodes, and biomarker immunofluorescence was measured. Electrodes were then imaged on a scanning electron microscope to assess sustained electrode damage. Fluorescence and electron microscopy analyses suggest varying degrees of localized responses for each biomarker assayed (Hoescht, EGFP, GFAP, and IL-1β), a result that expands on comparable in vivo models. This system allows for the comparison of a breadth of electrical stimulation parameters, and opens another avenue through which neural interfacing device developers can improve biocompatibility and longevity of electrodes in tissue.

Changes in sensitivity and hedonic rating to transcutaneous electrical nerve stimulation following COVID-19

COVID-19 affects not only the respiratory system but also other biological systems such as the nervous system. Usually, these changes are reported based on the patient's subjective description. The aim of our study, therefore, was to objectively determine the effect that the SARS-CoV-2 virus and COVID-19 disease has on sensory threshold and the hedonic and subjective perception of an electrical stimulus. The sensory threshold was tested on the inner forearm by applying non-invasive transcutaneous electrical nerve stimulation (TENS) with 100 Hz and 100 µs parameters and a biphasic current waveform. The study involved 211 participants, aged 22–79 years, with a mean age of 56.9 ± 12.1 years. There were 131 subjects in the COVID group, while the NON-COVID group, the control group, was matched to the COVID group in terms of gender, age, body mass index and presence of chronic diseases. The research was carried out in 2022. Sensory sensitivity was highest in the group that had suffered with COVID-19. The median sensory sensitivity was 11 mA in the COVID group and 14 mA (p < 0.001) in the NON-COVID group, however, the current sensitivity threshold decreased over time (R = 0.52, p < 0.001). Post COVID-19, the electrical stimulus was more often perceived as unpleasant: COVID versus NON-COVID (23% vs. 3%, p < 0.001) and as a different sensation to tingling (27% vs. 2%, p < 0.001). Post-COVID-19 patients have a lower sensory threshold, the electrical stimulus is more often described as unpleasant and in subjective feelings it is more often described as pinching. The differences between COVID and NON-COVID decrease with time since the onset of COVID symptoms.

Effect of Loading Frequency on the Fretting-Corrosion Degradation of the Stem-Head and Stem-Cement Interfaces in Hip Implants

Abstract Degradation by fretting-corrosion of the stem-head interface is considered the main source of the release of metal ions and debris, leading to adverse tissue reactions at the cemented total hip arthroplasty. The aim of this study was to investigate the effect of loading frequency on the fretting-corrosion degradation at the stem-head and stem-cement interfaces through electrochemical measurements during the benchtop testing. Different loading frequency conditions were investigated with the same number of cycles (1,000 cycles) to calculate the fretting current and Faraday mass loss. For both interfaces, there was a biphasic waveform response of the fretting current to the load applied, at 1 Hz, almost with phase opposition. An increase in the loading frequency (1 to 30 Hz) generated a higher fretting current for the stem-head (2.97 ± 2.04 μA to 7.66 ± 2.46 μA) and stem-cement (7.62 ± 2.26 μA to 25.48 ± 5.35 μA) interfaces. However, an increase in the loading frequency (1 to 30 Hz) reduced the Faraday mass loss of the stem-head (0.79 ± 0.54 μg to 0.07 ± 0.02 μg) and stem-cement (2.02 ± 0.62 μg to 0.32 ± 0.12 μg) interfaces because of a reduction in the overall testing time. Thus, there is a compromise relation between the fretting current and the Faraday mass loss, which must be considered when setting the loading frequencies in the fretting-corrosion benchtop testing of hip implants.

Analysis of dim-light responses in rod and cone photoreceptors with altered calcium kinetics

Rod and cone photoreceptors in the retina of vertebrates are the primary sensory neurons underlying vision. They convert light into an electrical current using a signal transduction pathway that depends on Ca^{2+} feedback. It is known that manipulating the Ca^{2+} kinetics affects the response shape and the photoreceptor sensitivity, but a precise quantification of these effects remains unclear. We have approached this task in mouse retina by combining numerical simulations with mathematical analysis. We consider a parsimonious phototransduction model that incorporates negative Ca^{2+} feedback onto the synthesis of cyclic GMP, and fast buffering reactions to alter the Ca^{2+} kinetics. We derive analytic results for the photoreceptor functioning in sufficiently dim light conditions depending on the photoreceptor type. We exploit these results to obtain conceptual and quantitative insight into how response waveform and amplitude depend on the underlying biophysical processes and the Ca^{2+} feedback. With a low amount of buffering, the Ca^{2+} concentration changes in proportion to the current, and responses to flashes of light are monophasic. With more buffering, the change in the Ca^{2+} concentration becomes delayed with respect to the current, which gives rise to a damped oscillation and a biphasic waveform. This shows that biphasic responses are not necessarily a manifestation of slow buffering reactions. We obtain analytic approximations for the peak flash amplitude as a function of the light intensity, which shows how the photoreceptor sensitivity depends on the biophysical parameters. Finally, we study how changing the extracellular Ca^{2+} concentration affects the response.

Positive and biphasic extracellular waveforms correspond to return currents and axonal spikes

Multiple biophysical mechanisms may generate non-negative extracellular waveforms during action potentials, but the origin and prevalence of positive spikes and biphasic spikes in the intact brain are unknown. Using extracellular recordings from densely-connected cortical networks in freely-moving mice, we find that a tenth of the waveforms are non-negative. Positive phases of non-negative spikes occur in synchrony or just before wider same-unit negative spikes. Narrow positive spikes occur in isolation in the white matter. Isolated biphasic spikes are narrower than negative spikes, occurring right after spikes of verified inhibitory units. In CA1, units with dominant non-negative spikes exhibit place fields, phase precession, and phase-locking to ripples. Thus, near-somatic narrow positive extracellular potentials correspond to return currents, and isolated non-negative spikes correspond to axonal potentials. Identifying non-negative extracellular waveforms that correspond to non-somatic compartments during spikes can enhance the understanding of physiological and pathological neural mechanisms in intact animals.

The Effects of Sex, Women’s Body Composition and Monthly Cycle Phases on the Sensory Threshold of Upper Limb to Transcutaneous Electrical Nerve Stimulation in Healthy Subjects

Neuromuscular excitability plays an essential role in electrotherapy treatment. The vast majority of these treatments are procedures that change the sensitivity to sensory stimuli, especially pain, with the use of an electric current. The aim of this study was to assess changes in the sensory threshold in response to transcutaneous electrical nerve stimulation (TENS), taking into account certain personal factors, such as sex, body composition, and phases of the menstrual cycle. The study involved 205 women and 49 men aged 19–33 years. Sensory threshold was examined by TENS stimulation (a biphasic current waveform, 100 Hz and 100 µs) and body composition using a TANITA analyzer. The mean sensitivity threshold in women was lower than in men (mean ± SD, F: 8.78 ± 2.11 mA vs. M: 11.20 ± 3.29 mA, p &lt; 0.001). There were no significant differences in sensory threshold during the different phases of a woman’s monthly cycle. The taller the woman, the higher the sensory threshold (B ± SE, 0.15 ± 0.07, p = 0.036), while those with a higher percentage of body fat and a higher total water content had a lower sensory threshold (fat: B ± SE, −0.25 ± 0.07, p &lt; 0.001; water: B ± SE, −0.20 ± 0.07, p = 0.003). In conclusion, the sensory threshold in women was lower than in men. In women aged 19–33 years, the phases of the monthly cycle did not affect the sensory threshold; however, being taller and having less body fat and a lower water content increased the sensory threshold.

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

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. In the study, lesions were generated by applying IRE in porcine and human left ventricles using a pair of parallel needle electrodes at different voltages (500-1500 V) and two different pulse waveforms: a proprietary biphasic waveform (Medtronic) and monophasic 48 × 100 μs pulses. The lethal electric field threshold, anisotropy ratio, and conductivity increase by electroporation were determined by numerical modeling, comparing the model outputs with segmented lesion images. The median threshold was 535V/cm in porcine ((N = 51 lesions in n = 6 hearts) and 416V/cm in the human donor hearts ((N = 21 lesions in n = 3 hearts) for the biphasic waveform. The median threshold value was 368V/cm in porcine hearts ((N = 35 lesions in n = 9 hearts) cm for 48 × 100 μs pulses. The values obtained are compared with an extensive literature review of published lethal electric field thresholds in other tissues and were found to be lower than most other tissues, except for skeletal muscle. These findings, albeit preliminary, from a limited number of hearts suggest that treatments in humans with parameters optimized in pigs should result in equal or greater lesions.

Pulsed-field ablation versus single catheter high-power short-duration radiofrequency ablation for atrial fibrillation: procedural characteristics, myocardial injury and midterm outcomes

Abstract Funding Acknowledgements Type of funding sources: None. Background Pulsed-field ablation (PFA) has emerged as a novel treatment strategy for patients with atrial fibrillation (AF). A direct comparison to high-power short-duration (HPSD) radiofrequency (RF) ablation using a single catheter is lacking. Aim To compare pulmonary vein isolation (PVI) using PFA versus single catheter HPSD-RF ablation regarding efficiency, safety, myocardial injury, and outcomes. Methods 119 patients underwent PVI and were included (age 65.6 ± 10 years, ejection fraction 0.55 ± 0.11, left atrial size 41 ± 6.6 mm, paroxysmal AF 55%). 56 patients (47%) underwent PFA using a multi-electrode pentaspline PFA catheter with a biphasic waveform and 63 patients (53%) underwent single catheter HPSD-RF ablation without a multipolar mapping catheter. Results Using PFA the median procedure time was significantly shorter compared to the single catheter HPSD-RF group with 58 (IQR 51-70) min versus 83 (IQR 71-99) min (p&amp;lt;0.001), while fluoroscopic time was significantly longer with 12 (IQR 10-16) min versus 2.2 (IQR 1.3-3.6) min (p&amp;lt;0.001). First-pass isolation was achieved in 91% of the PFA group and 88% in the HPSD-RF group. 3.3 catheters vs. 1.0 catheters were used in the PFA group versus the HPSD-RF group, p&amp;lt;0.01. One procedural complications was observed in the PFA group and one complication in the HPSD-RF group (Tamponades). High sensitivity cardiac troponin levels were on average significantly higher in patients using the PFA system, 1520 (IQR 1010-1980) ng/l compared to 897 (IQR 725-1240) ng/l in the HPSD-RF group. During a median follow-up of 177 days (IQR 92-300), AF recurrence was observed in five patients (9%) from the PFA group and in 15 patients (24%) from the HPSD-RF group. (Figure 1) Conclusion PFA showed shorter procedure times but longer fluoroscopy times, higher levels of hs cTnT, and a possible improved AF-free survival.

Amplitude of spectral area of ventricular fibrillation as a guide for low energy defibrillation level in patients with out-of-hospital cardiac arrest

Abstract Funding Acknowledgements Type of funding sources: None. Introduction The optimal energy level for shock in biphasic waveform defibrillation represents a significant knowledge gap. Different energy regimens have been trialed; however, a selection criterion which may help in adopting one approach over another has never been identified. Choosing the maximum energy may be an option but current-induced myocardial damage should not be neglected and an effort to tailor energy delivery is desirable. Purpose To assess whether amplitude spectral area (AMSA) of VF can guide the dose-regimens of defibrillation in out-of-hospital cardiac arrest (OHCA) patients. Methods This is a multicenter study based on the data from some of the largest OHCA registers in Europe, which enrolled 830 OHCA patients who received at least one shock during advanced resuscitation. AMSA values were calculated by retrospectively analyzing the data collected by the Corpuls 3 and LIFEPAK 12/15 monitors/defibrillators and by using a 2-second-pre-shock ECG interval. Results Among 830 OHCAs, 2135 shocks were delivered from a minimum energy level of 150 J to a maximum of 360 J. The AMSA values of efficacious shocks delivered at 150 J were higher compared to those of efficacious shock at 360 J [13.1 (IQR 10.2-17.1) vs 11.8 (IQR 8.3-15.2) HzxmV; p&amp;lt;0.01). In a multivariate analysis corrected for time to each shock, sex, age, amiodarone administration and study center, AMSA values, and not the dose of the shock energy, was significantly associated with the probability of shock success [OR 5.8, (95%CI 4.7-7.3); p&amp;lt; 0.01]. By dividing the total shocks into three tertiles based on AMSA values (T1: 0.8-6.9 Hz×mV; T2: 6.9-11.8 Hz×mV; T3: 11.8-63.2 Hz×mV), the rate of shock success at low energy was significantly higher in the tertile with highest AMSA values (T3: 38% vs T2: 15% vs T1: 5%; p&amp;lt;0.01). Particularly in T3, low energy was more effective than high energy shocks (38% vs 23%, p &amp;lt; 0.001). Conclusion This is the first study to identify a datapoint to guide decision-making with regards to defibrillation with lower energy levels. AMSA could indeed guide the selection of energy levels in order to optimize efficaciousness in restoring a perfusing rhythm while minimizing the contribution to myocardial dysfunction.

PO-01-187 FEASIBILITY OF FLUOROLESS PULMONARY VEIN ISOLATION USING A SINGLE-SHOT CONFORMABLE PULSED FIELD ABLATION CATHETER

Fluoroless pulmonary vein isolation (PVI) using point-by-point ablation catheters guided by electroanatomical mapping (EAM) systems is standard practice in many operators’ practice. While “single-shot” PVI tools have a streamlined procedural workflow, and with a safety profile enhanced by the emergence of pulsed field ablation (PFA) technology, these catheters have not been able to support a completely fluoroless workflow. A novel 8-Fr single-shot large lattice catheter with integrated magnetically-tracked EAM and PFA capabilities has been developed. To report for the first time the feasibility of performing single-shot PVI using a completely fluoroless approach. This 8 Fr PFA catheter (SpherePVI; Affera-Medtronic Inc) has a conformable large lattice framework that is expandable to 34 mm in diameter to permit “customization” to varying pulmonary vein anatomies (see Figure). It was delivered using an 8.5 Fr deflectable sheath (Agilis, Abbott Inc), and used with a custom EAM system (Prism-1; Affera-Medtronic Inc.) to render PV and left atrial anatomy. The PFA generator (HexaPULSE; Affera-Medtronic Inc) delivered biphasic waveforms (5 sec per application; 1.3-2.0 kV[±]); goal of 1-3 lesions per PV) from six elements situated circumferentially around the equatorial plane of the lattice. These cases conducted at a single center as part of a first-in-human study (NCT05115214): under general anesthesia, ICE was used to guide transeptal puncture and catheter positioning; fluoroscopy was initially used, followed by completely fluoroless ablation (using only ICE and EAM). The fluoroless cohort (n = 4 AF pts) was well matched with the control cohort (n = 5 AF pts) with similar baseline characteristics except for having more male patients (see Table). PVI was 100% successful in both groups. For PVI, both the number of PFA lesions delivered (16.3±0.5 vs 16.6±0.9 in the fluoroless and control groups, respectively) and the PVI ablation times (time only during lesion application; 1.6±0.0 min vs 1.6±0.1 min), and transpired time (defined as time transpiring between first to last lesion application; 8.3±1.1 min vs 9.6±2.2 min) were comparable. The total fluoroscopy time in the control group was 5.5±2.7 min. There were no serious adverse events in either group. This case series provides the proof-of-principle that fluoroless single-short PVI is feasible, safe and effective using a conformable large lattice PFA catheter.

Evaluating the prognostic performance of bedside tests used for peripheral arterial disease diagnosis in the prediction of diabetic foot ulcer healing

IntroductionDiabetic foot ulceration (DFU) is a common and challenging complication of diabetes. Risk stratification can guide further management. We aim to evaluate the prognostic performance of bedside tests used for...