Bipolar endo-epicardial RF ablation: Animal feasibility study.

BACKGROUND: Bipolar radiofrequency ablation (B-RFA) is a method used to treat the arrhythmia substrate resistant to unipolar ablation. Few studies have addressed endo-epicardial B-RFA. OBJECTIVE: The aim of the study was to evaluate chronic lesions resulting from endo-epicardial B-RFA and to determine optimal settings for such procedures in an animal model. METHODS: In 7 pigs, up to 5 radiofrequency applications per animal were performed with 2 electrodes placed on both sides of the left ventricular free wall. Current was delivered for 60 seconds by a generator dedicated for B-RFA with power settings of 25, 30, 35, 40, and 50 W. RESULTS: At 12 weeks after ablation, 31 lesions were assessed. Their maximal cross-sectional area ranged from 7.2 to 68 mm2 and correlated with total power delivered (r = 0.53), with temperature increment at the endocardial catheter (r = 0.65), and inversely with temperature decrement at the epicardial catheter (r = 0.54). For power values between 30 and 40 W, the lesion area did not differ significantly (P = .92). Lesion depth ranged from 1.9 to 11 mm and correlated with impedance decrement (r = 0.5). Lesions were transmural in 8 cases. Lesion depth/wall thickness ratio was on average 0.6 ± 0.3, with the smallest value for 25 W (0.5 ± 0.3) and the largest for 50 W (0.8 ± 0.3). Steam pops occurred at a power range of 30-50 W, with an incidence of 1 in 5 applications, with 1 case of fatal tamponade at 40 W. Impedance decrement, endocardial catheter temperature increment, and endocardial electrogram amplitude decrement were greater during applications with steam pops. CONCLUSION: Chronic lesions resulting from endo-epicardial B-RFA appear smaller and less often transmural compared with acute lesions described in the literature. The incidence of steam pops during endo-epicardial B-RFA is relatively high even at low powers.

Realization of either physisorption or chemisorption of 2H-tetraphenylporphyrin on the Cu(111) from density functional theory.

The adsorption of organic molecules to surfaces is a central issue to achieve fully-functional molecular devices, for which porphyrins are well-studied due to their chemical stability and functional diversity. Herein, we investigate both the physical and the chemical adsorption of the free-base tetraphenylporphyrin 2H-TPP on the Cu(111) surface within the framework of density functional theory and find that the most stable physisorbed configuration is more weakly bound by -0.31 eV than the chemisorbed configuration. We use the electron localization function to investigate the difference in binding mechanisms between strong physisorption and weak chemisorption. We have computed a reaction barrier of 0.12 eV in going from physical binding to chemical bonding to the surface, and a barrier of 50 meV in going between neighboring physical binding sites. Our results support the possibility of realizing free-base porphyrins either physisorbed or chemisorbed on Cu(111) depending on the deposition procedure and experimental conditions.

Bipolar catheter ablation with dedicated radiofrequency system for highly refractory ventricular arrhythmia-Does the rate of success depend on arrhythmia origin?

INTRODUCTION: Despite rapid technological progress, some arrhythmias are still resistant to standard unipolar ablation. These include arrhythmias arising from the base of the heart, cardiac crux, or epicardium. Bipolar radiofrequency ablation (B-RFA) may be useful in some cases, however, data on the efficacy of this approach in various arrhythmia localizations are scarce. The aim of this study was to assess the efficacy of B-RFA in patients with ventricular arrhythmias originating from various locations, occurring refractory to standard unipolar ablation approaches. METHODS: An observational, single center study was conducted over a 30-month period. B-RFA were performed using dedicated radio frequency (RF) generator and electroanatomic mapping system. RESULTS: Twenty-four procedures, in 23 patients with a median (range) of 1 (1-2) previously failed unipolar ablation procedures, were included in the final analysis. There were 12 ablations of ventricular arrhythmias originating from interventricular septum with an acute success rate of 75%, and 12 from left ventricular (LV) summit with an acute success rate of 58%. The midterm success rate (median interquartile range follow-up of 205 days [188-338]) was 66% and 50%, respectively. CONCLUSIONS: B-RFA is a promising method of catheter ablation for refractory cardiac arrhythmias. A higher success rate was observed in ablation for difficult ventricular arrhythmias originating from interventricular septal region than LV summit.

Feasibility of the J-PET to monitor the range of therapeutic proton beams.

PURPOSE: The aim of this work is to investigate the feasibility of the Jagiellonian Positron Emission Tomography (J-PET) scanner for intra-treatment proton beam range monitoring. METHODS: The Monte Carlo simulation studies with GATE and PET image reconstruction with CASToR were performed in order to compare six J-PET scanner geometries. We simulated proton irradiation of a PMMA phantom with a Single Pencil Beam (SPB) and Spread-Out Bragg Peak (SOBP) of various ranges. The sensitivity and precision of each scanner were calculated, and considering the setup's cost-effectiveness, we indicated potentially optimal geometries for the J-PET scanner prototype dedicated to the proton beam range assessment. RESULTS: The investigations indicate that the double-layer cylindrical and triple-layer double-head configurations are the most promising for clinical application. We found that the scanner sensitivity is of the order of 10-5 coincidences per primary proton, while the precision of the range assessment for both SPB and SOBP irradiation plans was found below 1 mm. Among the scanners with the same number of detector modules, the best results are found for the triple-layer dual-head geometry. The results indicate that the double-layer cylindrical and triple-layer double-head configurations are the most promising for the clinical application, CONCLUSIONS:: We performed simulation studies demonstrating that the feasibility of the J-PET detector for PET-based proton beam therapy range monitoring is possible with reasonable sensitivity and precision enabling its pre-clinical tests in the clinical proton therapy environment. Considering the sensitivity, precision and cost-effectiveness, the double-layer cylindrical and triple-layer dual-head J-PET geometry configurations seem promising for future clinical application.

Cardioneuroablation for reflex asystolic syncope: Mid-term safety, efficacy, and patient's acceptance.

BACKGROUND: Cardioneuroablation (CNA) is a promising therapy for reflex asystolic syncope; however, convincing data on the mid-term safety and efficacy of this procedure are lacking. OBJECTIVE: The purpose of this study was to assess the mid-term safety, efficacy, and patient acceptance of CNA. METHODS: This prospective observational single-center study included 115 consecutive patients (mean age 39 ± 13 years; 58% female) treated between 2016 and 2022 who completed at least 1-year follow-up. RESULTS: No significant procedure-related acute complications occurred. During median follow-up of 28 months (range 12-75), 95 (83%) remained free from syncope. Of the 20 patients (17%) with syncope recurrence, syncope burden decreased from a mean 17 (median 6.5) to 3.75 (median 2.5) episodes (P = .015). In 9 of 10 patients, pacing system removal was possible. Repeated CNA was needed in 3 patients (3%), whereas pacemaker implantation was performed in 5 (4%). The most frequent mid-term complication of CNA was sinus rhythm acceleration (from 60 ± 14 bpm to 90 ± 16 bpm; P <.0001), which was symptomatic in 31 patients (27%); 8 patients (7%) required chronic beta-blocker and/or ivabradine. Sinus node modification was necessary in 1 patient. Other complaints included dyspnea, chronic chest pain, and decreased exercise capacity, which were mild and reported by 16 patients (14%). Patient acceptance of CNA was very high: 96% stated that it was worth undergoing the procedure. CONCLUSIONS: Mid-term efficacy of CNA exceeds 80%, and acute complications are absent. The most frequent mid-term chronic complication is inappropriate sinus tachycardia, which in 7% required chronic treatment. The procedure is well accepted by patients.

Variability of baroreceptor reflex assessed by tilt table test in a patient undergoing pulmonary vein isolation.

BACKGROUND: The autonomic nervous system (ANS) plays a significant role in atrial fibrillation (AF). Catheter ablation (CA) affects the ANS balance. The assessment of baroreceptor (BR) function is an established method to measure parasympathetic activity; however, it has been rarely used in patients undergoing CA of AF. AIMS: This study is to assess changes in BR function caused by CA and to compare these changes between two different types of CA: point-by-point radiofrequency (RF) versus cryoballoon (CB). METHODS: In this observational, prospective, single center study, 78 patients (25 females, mean age 58 ± 9) with paroxysmal AF and first CA were included: 39 patients (RF group) and 39 (CB group). The BR function was assessed non-invasively using tilt testing and three parameters: event count (BREC) depicting overall BR activity, slope mean depicting BR sensitivity (BRS), and BR effectiveness index (BEI). RESULTS: The groups did not differ in clinical or demographic data. Before CA, tilting caused a marked decrease in BR function parameters in the whole study group (BREC (29 ± 14.0-50.0 vs 28 ± 9.0-44.0, p < 0.068), BRS (10.2 ± 7.1-13.2 vs 5.8 ± 4.9-8.5; p < 0.001), and BEI (52.9 ± 39.9-65.5 vs 39.6 ± 23.6-52.1; p < 0.001), supine vs tilting, respectively). These changes were similar in the both groups. After CA, BR function decreased in the whole group (BREC 12.0 ± 3.0-22.0 vs 6.0 ± 3.0-18.0, p = 0.004; BRS 4.8 ± 3.6-6.8 vs 4.0 ± 3.0-5.8, p = 0.014; BEI 18.7 ± 8.3-27.4 vs 12.0 ± 5.1-21.0, p = 0.009). BREC was significantly more decreased in the CB vs RF. Similar trend was noted for BRS and BEI. CONCLUSIONS: CA significantly affects BR function. These changes were more pronounced following CB rather than RF CA.

Transformation of PET raw data into images for event classification using convolutional neural networks.

In positron emission tomography (PET) studies, convolutional neural networks (CNNs) may be applied directly to the reconstructed distribution of radioactive tracers injected into the patient's body, as a pattern recognition tool. Nonetheless, unprocessed PET coincidence data exist in tabular format. This paper develops the transformation of tabular data into n-dimensional matrices, as a preparation stage for classification based on CNNs. This method explicitly introduces a nonlinear transformation at the feature engineering stage and then uses principal component analysis to create the images. We apply the proposed methodology to the classification of simulated PET coincidence events originating from NEMA IEC and anthropomorphic XCAT phantom. Comparative studies of neural network architectures, including multilayer perceptron and convolutional networks, were conducted. The developed method increased the initial number of features from 6 to 209 and gave the best precision results (79.8) for all tested neural network architectures; it also showed the smallest decrease when changing the test data to another phantom.

Subclinical Dysfunction of Left Atrial Compliance after Cryoballoon versus Radiofrequency Ablation for Paroxysmal Atrial Fibrillation.

It has been suggested that cryoballoon (CB) ablation for paroxysmal atrial fibrillation (PAF) may lead to more extensive left atrial (LA) injury than radiofrequency (RF) ablation; however, results are conflicting. We sought to address this issue using modern echocardiographic techniques estimating the LA function after successful CB and RF ablation for PAF. A total of 90 patients (66% males, mean age 57 ± 10 years) successfully treated (no AF recurrences confirmed in serial 4-7 day ECG Holter monitoring) with RF (51%) or CB (49%) ablation for PAF were retrospectively studied. Echocardiography with speckle tracking (STE) was performed before and 12 months after the procedure. The peak longitudinal LA strain (LAS) and strain rate (LASR) during the reservoir (r), conduit (cd), and contraction (ct) phases were measured in sinus rhythm. Analysis of covariance was applied to compare changes in the echocardiographic parameters over time with the baseline measurements as covariance and the type of ablation as the factor. The parallelism of the slopes of the covariance was tested. The LA diameter decreased (38.3 ± 4.1 mm vs. 36.8 ± 3.6 mm, p < 0.001) in the whole study group at 12 months after ablation. The LASRr and LASRcd increased (1.1 ± 0.3 s-¹ vs. 1.3 ± 0.3 s-¹, p < 0.001 and 1.1 ± 0.3 s-¹ vs. 1.2 ± 0.3 s-¹, p < 0.001, respectively) whereas other LA strain parameters remained unchanged in the whole study group at 12 months after ablation. In the analysis of LA function at 12 months after the procedure regarding the mode of ablation, the worsening of parameters reflecting LA compliance was observed in patients with better pre-served baseline values in the CB ablation subgroup. For baseline LAScd >28%, the difference ΔCB - ΔRF was -7.6 (11.7; -3.4), p < 0.001, and for baseline LAScd >16%, ΔCB - ΔRF was -1.8 (-3.2; -0.4), p = 0.014. The traditional Doppler-derived parameter e' showed the same trend-for baseline e' ≥12 cm/s, ΔCB - ΔRF was -1.7 (-2.8; -0.6), p = 0.003. We conclude that worsening of parameters reflecting LA compliance was observed 12 months after CB ablation compared to RF ablation for PAF in patients who underwent a successful procedure and had better-preserved baseline LA function. This might suggest subclinical dysfunction of LA after the CB ablation procedure. The clinical significance of these findings warrants further investigations.

Detection of range shifts in proton beam therapy using the J-PET scanner: a patient simulation study.

OBJECTIVE: The Jagiellonian PET (J-PET) technology, based on plastic scintillators, has been proposed as a cost effective tool for detecting range deviations during proton therapy. This study investigates the feasibility of using J-PET for range monitoring by means of a detailed Monte Carlo simulation study of 95 patients who underwent proton therapy at the Cyclotron Centre Bronowice (CCB) in Krakow, Poland. Approach: Discrepancies between prescribed and delivered treatments were artificially introduced in the simulations by means of shifts in patient positioning and in the Hounsfield unit to the relative proton stopping power calibration curve. A dual-layer, cylindrical J-PET geometry was simulated in an in-room monitoring scenario and a triple-layer, dual-head geometry in an in-beam protocol. The distribution of range shifts in reconstructed PET activity was visualised in the beam's eye view. Linear prediction models were constructed from all patients in the cohort, using the mean shift in reconstructed PET activity as a predictor of the mean proton range deviation. Main results: Maps of deviations in the range of reconstructed PET distributions showed agreement with those of deviations in dose range in most patients. The linear prediction model showed a good fit, with coefficient of determination r^2 = 0.84 (in-room) and 0.75 (in-beam). Residual standard error was below 1 mm: 0.33 mm (in-room) and 0.23 mm (in-beam). Significance: The precision of the proposed prediction models shows the sensitivity of the proposed J-PET scanners to shifts in proton range for a wide range of clinical treatment plans. Furthermore, it motivates the use of such models as a tool for predicting proton range deviations and opens up new prospects for investigations into the use of intra-treatment PET images for predicting clinical metrics that aid in the assessment of the quality of delivered treatment. .

Is catheter-tissue contact force value important for ablation of ventricular arrhythmias originating from the left ventricular papillary muscles?

Background: Good catheter-tissue contact is mandatory to create effective ablation lesions. The minimal contact force value for ablation of arrhythmias originating from the left ventricle is 8.0-10.0 grams but is not known for arrhythmias arising from papillary muscles. Purpose: To analyze contact force values during successful ablation procedures of arrhythmias originating from the left ventricular papillary muscles. Methods: 24 consecutive patients (mean age 57.9 ± 11.9 years, 16 males) underwent ablation of premature ventricular complexes originating from left ventricular papillary muscles with the use of CARTO electro-anatomical system and intracardiac echocardiography. Results: Acute complete abolition of ventricular ectopy was obtained in 23 (96%) patients. The fluoroscopy time was 3.9 ± 3.5 min and procedure duration - 114.8 ± 37.9 min. The mean contact force during successful ablations was 3.0 ± 1.1 grams and 3.18 ± 1.8 grams for antero-lateral and postero-medial papillary muscle, respectively (NS). The mean contact force during a single unsuccessful ablation was 3.0 grams. At control Holter ECG, the mean Ectopy Burden was Reduced in the Antero-Lateral Papillary Muscle Group from 18.0% ± 7.9% to 2.6% ± 2.9% (p = 0.005415) and in the Postero-Medial Papillary Muscle Group - from 34.8% ± 13.7%-1.7% ± 1.3% (p = 0.012694). During Median 27 (IQR: 17-34) Months of Follow-up There one Recurrence of Arrhythmia. Conclusion: The values of contact force for successful ablation of ventricular ectopy originating from the left ventricular papillary muscles may be much lower than those for ablation of other foci which questions the role of contact force measurement when ablating these arrhythmias.

Optically Stimulated Luminescent Response of the LiMgPO4 Silicone Foils to Protons and Its Dependence on Proton Energy.

Modern radiotherapy (RT) techniques, such as proton therapy, require more and more sophisticated dosimetry methods and materials. One of the newly developed technologies is based on flexible sheets made of a polymer, with the embedded optically stimulated luminescence (OSL) material in the form of powder (LiMgPO4, LMP) and a self-developed optical imaging setup. The detector properties were evaluated to study its potential application in the proton treatment plan verification for eyeball cancer. The data showed a well-known effect of lower luminescent efficiency of the LMP material response to proton energy. The efficiency parameter depends on a given material and radiation quality parameters. Therefore, the detailed knowledge of material efficiency is crucial in establishing a calibration method for detectors exposed to mixed radiation fields. Thus, in the present study, the prototype of the LMP-based silicone foil material was tested with monoenergetic uniform proton beams of various initial kinetic energies constituting the so-called spread-out Bragg peak (SOBP). The irradiation geometry was also modelled using the Monte Carlo particle transport codes. Several beam quality parameters, including dose and the kinetic energy spectrum, were scored. Finally, the obtained results were used to correct the relative luminescence efficiency response of the LMP foils for monoenergetic and spread-out proton beams.

Cardioneuroablation for Reflex Syncope: Efficacy and Effects on Autonomic Cardiac Regulation-A Prospective Randomized Trial.

BACKGROUND: Treatment of cardioinhibitory vasovagal syncope (VVS) is difficult. Recently, cardioneuroablation (CNA) has emerged as a new therapeutic option. OBJECTIVES: This study sought to assess the effects of CNA on syncope recurrences in patients with VVS. METHODS: This study was a prospective, open, randomized, controlled, investigator-initiated trial comparing CNA versus optimal nonpharmacologic therapy in patients with cardioinhibitory VVS. Patients were included if they had documented symptomatic cardioinhibitory or mixed VVS and positive atropine test. CNA was performed using radiofrequency ablation of the ganglionated plexi from the left and right atria. Follow-up lasted 2 years. Primary endpoint was time to first syncope recurrence. Secondary endpoints included changes in sinus rhythm and heart rate variability measured in Holter electrocardiography at baseline and 3, 12, and 24 months after CNA, as well as changes in quality of life at baseline and after completion of follow-up. RESULTS: A total of 48 patients (17 male, mean age 38 ± 10 years, 24 in CNA group, 24 in control group) entered the study. The primary endpoint occurred in 2 patients (8%) from the CNA group versus 13 control patients (54%) (P = 0.0004). After CNA the mean sinus rhythm at 24-hour Holter electrocardiography was significantly faster and heart rate variability parameters significantly changed toward parasympathetic withdrawal compared with baseline values. Quality of life significantly improved in the CNA group (30 ± 10 points vs 10 ± 7 points; P = 0.0001), whereas it remained stable in control patients (31 ± 10 points vs 30 ± 10 points; P = 0.5501). CONCLUSIONS: This is the first randomized study documenting efficacy of CNA in patients with cardioinhibitory VVS. Larger studies are needed to confirm these findings. (Cardioneuroablation for Reflex Syncope [ROMAN]; NCT03903744).

Impaired coronary flow reserve in patients with poor type 2 diabetes control: Preliminary results from prospective microvascular dysfunction registry.

BACKGROUND: Type 2 diabetes (DM) is a common comorbidity associated with cardiovascular disease, especially when poor glucose control is present. Extracardiac microcirculatory complications prevalence is well documented, however coronary microcirculatory dysfunction (CMD) seem to be underreported in this group. METHODS: The present study analyzed coronary physiology measurements (coronary flow reserve [CFR], index of microcirculatory resistance [IMR], resistance reserve ratio [RRR]) in 47 diabetic patients (21 subjects with poor glycemia control defined as fasting glucose levels > 7.2 mmol/L and 26 with normal fasting glucose), and compared to 54 non-diabetic controls, who had undergone coronary angiography due to symptoms of chronic coronary syndrome. The median age of patients was 65.5 [59.0; 73.0] years old, 74% male, similar in terms of cardiovascular risk factors and prior myocardial infarction. Insulin was used by 19% of diabetic patients with poor glucose control and by 15% of those with DM and low fasting glucose. RESULTS: Prevalence of CMD was 38% in poor glycemia control patients, 27% in DM-patients with proper glucose control and 31% of non-diabetics. Median CFR values were the lowest in poor DM control patients compared to both, normal fasting glucose (1.75 [1.37; 2.32] vs. 2.30 [1.75; 2.85], p = 0.026) and to non-diabetics (1.75 [1.37; 2.32] vs. 2.15 [1.50; 2.95], p = 0.045). Levels of IMR, RRR and MRR did not differ significantly between compared groups (p > 0.05 for all comparisons). CONCLUSIONS: Poor glycemia control in type 2 DM might be associated with a higher prevalence of CMD driven by decreased coronary flow reserve, however, further research in larger groups of patients should be performed to confirm this observation.

ProTheRaMon - a GATE simulation framework for proton therapy range monitoring using PET imaging.

OBJECTIVE: This paper reports on the implementation and shows examples of the use of the ProTheRaMon framework for simulating the delivery of proton therapy treatment plans and range monitoring using positron emission tomography (PET). ProTheRaMon offers complete processing of proton therapy treatment plans, patient CT geometries, and intra-treatment PET imaging, taking into account therapy and imaging coordinate systems and activity decay during the PET imaging protocol specific to a given proton therapy facility. We present the ProTheRaMon framework and illustrate its potential use case and data processing steps for a patient treated at the Cyclotron Centre Bronowice (CCB) proton therapy center in Krakow, Poland. APPROACH: The ProTheRaMon framework is based on GATE Monte Carlo software, the CASToR reconstruction package and in-house developed Python and bash scripts. The framework consists of five separated simulation and data processing steps, that can be further optimized according to the user's needs and specific settings of a given proton therapy facility and PET scanner design. MAIN RESULTS: ProTheRaMon is presented using example data from a patient treated at CCB and the J-PET scanner to demonstrate the application of the framework for proton therapy range monitoring. The output of each simulation and data processing stage is described and visualized. SIGNIFICANCE: We demonstrate that the ProTheRaMon simulation platform is a high-performance tool, capable of running on a computational cluster and suitable for multi-parameter studies, with databases consisting of large number of patients, as well as different PET scanner geometries and settings for range monitoring in a clinical environment. Due to its modular structure, the ProTheRaMon framework can be adjusted for different proton therapy centers and/or different PET detector geometries. It is available to the community via github.

Association Between Left Atrial Appendage Morphology and Function and the Risk of Ischaemic Stroke in Patients with Atrial Fibrillation.

AF is the most common cardiac arrhythmia and has been identified as an independent risk factor for stroke. The European Society of Cardiology guidelines recommend a thromboembolic event risk assessment based on the CHA2DS2-VASc score. However, stroke also occurs in some patients with a low CHA2DS2-VASc score. Therefore, it is necessary to find new factors to improve thromboembolic risk stratification in AF patients. Over 90% of embolic strokes are caused by thrombi originating from the left atrial appendage (LAA). Thus, certain anatomical or functional parameters of the LAA could potentially be used to predict cardioembolic stroke. Studies have suggested that some of these factors, such as LAA morphology, number of LAA lobes, LAA dimensions, LAA volume, distance from the LAA ostium to the first bend of LAA, LAA orifice diameter, extent of LAA trabeculations, LAA takeoff, LAA flow velocity and LAA strain rate, are independently associated with a higher risk of stroke in a population of patients with AF and improve the performance of the CHA2DS2-VASc score. However, the results are conflicting and, so far, no new parameter has been added to the CHA2DS2-VASc score.