Radiofrequency (RF) catheter ablation is a well-established therapeutic approach for treating arrhythmias, where lesion size and safety are critical for efficacy. This study explored the impact of varying irrigation flow rates on lesion characteristics using the TactiFlex™ SE Ablation Catheter (TF) in an ex vivo porcine heart model, focusing on the size and safety outcomes associated with low versus standard flow rates. Myocardial slabs from porcine hearts were subjected to ablation using two types of irrigated catheters. Lesion formation was compared between low (8 mL/min for TF) and standard irrigation flow rates (13 mL/min for TF) across different power settings (30, 40, and 50 W). Outcome measures included lesion dimensions, incidence of steam pops, and impedance drops. A total of 210 lesions were generated under various settings. At low flow rates, the TF catheter safely formed larger lesions compared to the standard flow rates without a significant increase in steam pops or impedance drops. Lesions at low flow rates were comparable in size to those formed using other catheters under the standard settings. Conversely, the standard flow settings for TF produced smaller lesions but exhibited higher safety profiles, as evidenced by fewer steam pops and impedance drops. Lower irrigation flow rates using a TF catheter can achieve larger lesions without compromising safety, offering an optimization strategy for RF ablation procedures that balances efficacy and safety. These findings may guide clinicians in tailoring ablation strategies according to individual patient needs.

Atrial fibrillation (AF) is a common cardiac arrhythmia, and ablation is the primary treatment for patients with drug intolerance. The success of AF ablation depends on the adhesion of the catheter to the tissue. Existing electrical coupling index (ECI) and electrode-interface resistance (IR) methods based on impedance measurement to evaluate the adhesion between catheters and tissues do not explore the internal changes of the tissue during the compression process. This study introduces a new method to understand these internal changes using multi-frequency impedance combined with Cole-Cole model fitting, which is critical for accurate characterization of the contact between catheter and tissue. We used four-electrodes impedance measurement, using customized circuits and compression platform, applying 5-400 g (3.6-228.2 Pa) pressure to the bullfrog thighs to collect impedance data at frequencies of 500-100 kHz. The Cole-Cole model was then used for data fitting and analysis. The customized circuit accurately detects impedance up to 2 kΩ with less than 5% amplitude error, less than 15% phase error, and less than 6% error in model component values. Correlation analysis showed a significant linear relationship between extracellular fluid resistance and applied pressure (Pearson R ≈ 0.9, p < 0.05), indicating that extracellular fluid resistance increases with compression. This suggests that there is a significant linear positive correlation between the extracellular fluid resistance and the applied pressure, meaning that as the pressure increases, the extracellular fluid resistance correspondingly rises. This may provide a new perspective for studying the degree of catheter-tissue contact during atrial fibrillation ablation procedures.

The Vizigo sheath, a novel visualizable steerable sheath, has been utilized effectively in the clinical management of atrial fibrillation. However, its application in the ablation of typical atrial flutter (AFL) remains unexplored. This study aims to evaluate and compare the efficacy and safety of the Vizigo sheath against a conventional fixed sheath during catheter ablation for typical AFL.

This single-center cohort study involved 60 patients undergoing their first AFL ablation procedure. Patients were divided into two groups: the Vizigo sheath group and the fixed sheath group. The primary endpoints included procedural efficiency, lesion quality, and recurrence rates.

The Vizigo sheath demonstrated significant advantages over the fixed sheath, including a shorter procedure time (59.8 ± 13.8 vs. 71.5 ± 11.8 min; p = 0.0008) and reduced fluoroscopy duration (0.96 ± 0.32 vs. 1.31 ± 0.24 min; p < 0.0001). The initial bidirectional block rate was also higher in the Vizigo sheath group (84% vs. 68%). A detailed analysis of the cavotricuspid isthmus (CTI) revealed significant differences in the anterior 2/3 of the CTI, where the Vizigo sheath demonstrated greater catheter contact force, higher ablation index, increased force-time integral, and larger impedance drops (all p < 0.05). In contrast, no significant differences were observed between groups in the posterior 1/3 of the CTI. Both groups achieved a 100% acute procedural success rate, with no major complications reported. During a mean follow-up period of 18.68 months, the AFL recurrence rates were comparable between the two groups (p = 0.75).

The Vizigo sheath enhances procedural efficiency and lesion quality during AFL ablation, particularly in challenging anatomical regions, and offers notable advantages over traditional fixed sheaths. Further studies are needed to assess its long-term clinical benefits.

Radiofrequency (RF) catheter ablation treats cardiac diseases by inducing thermal lesion of cardiac tissues through radiofrequency energy operating at around 500 kHz. The electromagnetic wavelength is significantly longer than the size of the radiofrequency active electrode, the tissue is heated through resistive heating. During thermal ablation, the coupled thermo-mechanical property of cardiac tissue influencing the contact area between the electrode and tissue plays a crucial role in the formation of thermal lesions, yet the literature often overlooks the effect of thermal deformation. This paper proposes a thermo-hyperelastic constitutive model for myocardium that models thermal contraction and expansion during ablation. Furthermore, a finite element model was established to investigate the effect of the electro-thermo-mechanical coupling property of myocardium on lesion formation under different contact forces. To ensure convergence, we solved the fully coupled electro-thermo-mechanical finite element model using the segregated step method. The computational results demonstrate that thermal deformation, which causes an expansion in the tissue-electrode contact area, increases lesion width and volume, while its influence on lesion depth is negligible. Specifically, after a 30-s ablation under contact forces of 0.1, 0.15, and 0.2 N, the lesion volume increased from 4.53, 7.66, and 10.62 mm3 (without thermo-mechanical coupling) to 5.36, 8.33, and 13.34 mm3 (with thermo-mechanical coupling), respectively. Similarly, the lesion width increased from 2.68, 3.12, and 3.44 mm to 2.78, 3.22, and 3.62 mm. Moreover, both thermal deformation and contact force exert a minimal effect on lesion formation time.

Ethanol infusion into the vein of Marshall (EIVOM) has been performed as an adjunctive atrial fibrillation therapy. However, the time course change, quantitative lesion investigation, and effects on epicardial fat pads and fractionated atrial electrograms created by EIVOM have never been investigated.

This study aimed to perform a quantitative analysis of lesions created by EIVOM.

We created voltage maps using a 3-dimensional mapping system immediately before and 30 minutes and 60 minutes after performing EIVOM to study the time course change in the lesions. We compared differences in the average contact force value required for successful conduction block in the Marshall vein area of patients with and without EIVOM. We also investigated effects of EIVOM on the area of complex fractionated atrial electrograms before and after EIVOM. We measured the total epicardial fat pad volume before and after EIVOM by computed tomography.

Voltage was significantly reduced after EIVOM, and there were significant differences in voltage reduction between the control status and 30 minutes and 60 minutes after EIVOM (P < .05). The average contact force value was significantly lower with vs without EIVOM (P < .05). The total epicardial fat volume and complex fractionated atrial electrogram area also significantly decreased after EIVOM (P < .05).

EIVOM provided significant therapeutic effects on the left atrial tissue perpetuating atrial fibrillation, which was demonstrated by a quantitative analysis.

Robot-assisted endovascular intervention has the potential to reduce radiation exposure to surgeons and enhance outcomes of interventions. However, the success and safety of endovascular interventions depend on surgeons' ability to accurately manipulate endovascular tools such as guidewire and catheter and perceive their safety when cannulating patient's vessels. Currently, the existing interventional robots lack a haptic system for accurate force feedback that surgeons can rely on. In this paper, a haptic-enabled endovascular interventional robot was developed. We proposed a dynamic hysteresis compensation model to address the challenges of hysteresis and nonlinearity in magnetic powder brake-based haptic interface, which were used for providing high-precision and higher dynamic range haptic perception. Also, for the first time, a human perceptual-based haptic enhancement model and safety strategy were integrated with the custom-built haptic interface for enhancing sensation discrimination ability during robot-assisted endovascular interventions. This can effectively amplify even subtle changes in low-intensity operational forces such that surgeons can better discern any vessel-tools interaction force. Several experimental studies were performed to show that the haptic interface and the kinesthetic perception enhancement model can enhance the transparency of robot-assisted endovascular interventions, as well as promote the safety awareness of surgeon.

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society, the Asia Pacific Heart Rhythm Society, and the Latin American Heart Rhythm Society.

Radiofrequency balloon (RFB) ablation (HELIOSTAR™, Biosense Webster) has been developed to improve pulmonary vein ablation efficiency over traditional point-by-point RF ablation approaches. We aimed to find effective parameters for RFB ablation that result in chronic scar verified by late gadolinium enhancement cardiac magnetic resonance (LGE-CMR).

A chronic canine model (n = 8) was used to ablate in the superior vena cava (SVC), the right superior and the left inferior pulmonary vein (RSPV and LIPV), and the left atrial appendage (LAA) with a circumferential ablation approach (RF energy was delivered to all electrodes simultaneously) for 20 s or 60 s. The electroanatomical map with the ablation tags was projected onto the 3-month post-ablation LGE-CMR. Tags were divided into two groups depending on whether they correlated with CMR-based scar (ScarTags) or non-scar tissue (Non-ScarTags). The effective parameters for scar formation were estimated by multivariate logistic regression.

This study assessed 80 lesions in the SVC, 80 lesions in the RSPV, 20 lesions in the LIPV, and 30 lesions in the LAA (168 ScarTags and 42 Non-ScarTags). In the multivariate analysis, two variables were associated with chronic scar formation: temperature of electrode before energy application (odds ratio (OR) 0.805, p = 0.0075) and long RF duration (OR 2.360, p = 0.0218), whereas impedance drop was not associated (OR 0.986, p = 0.373).

Lower temperature of the electrode before ablation and long ablation duration are critical parameters for durable atrial scar formation with RFB ablation.

This study aimed to identify the specific site of pulmonary vein conduction recovery after radiofrequency ablation (RFA) of atrial fibrillation (AF) for improved outcomes and reduced recurrence. Patients who underwent RFA for AF at our institution were included. The ablation procedure was guided by the ablation index (AI) and left, and right atrial pressures were monitored before and after ablation. Additionally, the recovery time of the sinoatrial node under Burst 400/300 ms stimulation was examined. Among 60 repeat procedure patients, 48 had paroxysmal and 12 had persistent AF. The recovery sites were 36.6% in the left anterior superior, 35% in the right anterior superior, 20% in the left anterior inferior, 20% in the right anterior inferior, 13.3% in the right top, and 11.6% in the left top. Preoperative and postoperative left and right atrial pressures were significantly higher in the persistent AF group compared with the paroxysmal AF group (P < 0.01). Postoperative left atrial pressures were significantly elevated compared to the preoperative levels in both groups (P < 0.01). Sinoatrial node recovery time in the persistent AF group was significantly longer compared with the paroxysmal AF group (P < 0.01). Under the guidance of AI, the recurrence of atrial fibrillation after radiofrequency surgery and the recovery of pulmonary vein potential are mostly concentrated in the upper anterior, lower anterior, and upper left and right pulmonary veins. As the duration of atrial fibrillation prolongs, the left and right atrial pressure increases year by year, while the recovery time of the sinus node gradually prolongs.

Acutely effective repeated radiofrequency catheter ablation (RFCA) after previous atrial fibrillation ablation depends on several parameters including local impedance (LI), contact force (CF), and power.

We aimed to investigate the relationship of LI, CF, and power to the LI drop in a repeated atrial RFCA environment.

Consecutive patients undergoing repeated atrial RFCA were studied. High-quality local electrograms were analyzed for morphology changes indicating effective RFCA and associated LI dynamics. The influence of baseline LI, mean CF, and power on the LI drop was analyzed. Investigated power levels included ≤25 W, 30 W, and ≥40 W.

A total of 1390 RFCA points from 48 patients (48% female; median age, 70 years) were analyzed. Of 309 analyzed electrograms, 40.5% showed effective RFCA morphology changes with an elevated median LI drop (effective, 19.7 Ω; partially effective, 14.1 Ω; P < .001). CF showed the highest correlation to the LI drop within high baseline LI and when applying ≥40 W (low baseline LI, R = 0.39; intermediate, R = 0.66; high, R = 0.72). Within low baseline LI regions, CF levels showed a lower correlation to the LI drop (≤25 W, R = 0.30; 30 W, R = 0.35; ≥40 W, R = 0.39). A mean CF ≥10 g resulted in elevated LI drops with higher power compared with lower power within all baseline LI tertiles (P < .001 each).

Within high baseline LI regions, CF plays a greater role for the maximum LI drop when higher power is chosen. A mean CF ≥10 g ensures elevated LI drops with increasing power levels.

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society, the Asia Pacific Heart Rhythm Society, and the Latin American Heart Rhythm Society.

Catheter-based cardiac ablation is a minimally invasive procedure for treating atrial fibrillation (AF). Electrophysiologists perform the procedure under image guidance during which the contact force between the heart tissue and the catheter tip determines the quality of lesions created. This paper describes a novel multi-modal contact force estimator based on Convolutional Neural Networks (CNNs) and Recurrent Neural Networks (RNNs). The estimator takes the shape and optical flow of the deflectable distal section as two modalities since frames and motion between frames complement each other to capture the long context in the video frames of the catheter. The angle between the tissue and the catheter tip is considered a complement of the extracted shape. The data acquisition platform measures the two-degrees-of-freedom contact force and video data as the catheter motion is constrained in the imaging plane. The images are captured via a camera that simulates single-view fluoroscopy for experimental purposes. In this sensor-free procedure, the features of the images and optical flow modalities are extracted through transfer learning. Long Short-Term Memory Networks (LSTMs) with a memory fusion network (MFN) are implemented to consider time dependency and hysteresis due to friction. The architecture integrates spatial and temporal networks. Late fusion with the concatenation of LSTMs, transformer decoders, and Gated Recurrent Units (GRUs) are implemented to verify the feasibility of the proposed network-based approach and its superiority over single-modality networks. The resulting mean absolute error, which accounted for only 2.84% of the total magnitude, was obtained by collecting data under more realistic circumstances in contrast to previous research studies. The decrease in error is considerably better than that achieved by individual modalities and late fusion with concatenation. These results emphasize the practicality and relevance of utilizing a multimodal network in real-world scenarios.

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society (HRS), the Asia Pacific HRS, and the Latin American HRS.

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.

Conventional focal radiofrequency catheters may be modified to enable multiple energy modalities (radiofrequency or pulsed field [PF]) with the benefit of contact force (CF) feedback, providing greater flexibility in the treatment of arrhythmias. Information on the impact of CF on lesion formation in PF ablations remains limited.

An in vivo study was performed with 8 swine using an investigational dual-energy CF focal catheter with local impedance. Experiment I: To evaluate atrial lesion formation, contiguity, and width, a point-by-point approach was used to create an intercaval line. The distance between the points was prespecified at 4±1 mm. Half of the line was created with radiofrequency energy, whereas the other half utilized PF (single 2.0 kV application with a proprietary waveform). Experiment II: To evaluate single application lesion dimensions with a proprietary waveform, discrete ventricular lesions were performed with PFA (single 2.0 kV application) with targeted levels of CF: low, 5 to 15 g; medium, 20 to 30 g; and high, 35 to 45 g. Following 1 week of survival, animals underwent endocardial/epicardial remapping, and euthanasia to enable histopathologic examination.

Experiment I: Both energy modalities resulted in a complete intercaval line of transmural ablation. PF resulted in significantly wider lines than radiofrequency: minimum width, 14.9±2.3 versus 5.0±1.6 mm; maximum width, 21.8±3.4 versus 7.3±2.1 mm, respectively; P<0.01 for each. Histology confirmed transmural lesions with both modalities. Experiment II: With PF, lesion depth, width, and volume were larger with higher degrees of CF (depth: r=0.82, P<0.001; width: r=0.26, P=0.052; and volume: r=0.55, P<0.001), with depth increasing at a faster rate than width. The mean depths were as follows: low (n=17), 4.3±1.0 mm; medium (n=26), 6.4±1.2 mm; and high (n=14), 9.1±1.4 mm.

Using the same focal point CF-sensing catheter, a novel PF ablation waveform with a single application resulted in transmural atrial lesions that were significantly wider than radiofrequency. Lesion depth showed a significant positive correlation with CF with depths of 6.4 mm at moderate CF.

Catheter ablation is a standard procedure in modern cardiology. It can significantly improve the quality of life and life expectancy of cardiac arrhythmia patients. Besides cardiac mapping, ablation itself is a fundamental step to successfully treat cardiac arrhythmias. There are various ablation technologies at hand: In traditional radiofrequency (RF) ablation, electrical current flow generates coagulation necrosis. When understanding the biophysical principles of RF ablation, the investigator is capable to adapt lesion geometry and size to the requirements of the procedure and vary them individually. In addition, lesion metric indices evaluate and integrate important parameters such as power, duration, impedance and contact force to standardize and control RF lesions. Cryoablation induces ice crystals within myocardial tissue, which lead to destruction and electrical scarring of the treated tissue. Histologically, cryolesions are well-delineated with preserved tissue architecture and intact endocardium. Pulsed field ablation (PFA) is a novel rising technology, particularly used for pulmonary vein isolation. In contrast to classic thermal technologies (RF and cryoablation), PFA uses pulsed electrical fields to electroporate cardiac tissue and thereby creates damage on a cellular level only.

Minimally invasive procedures assisted by soft robots for surgery, diagnostics, and drug delivery have unprecedented benefits over traditional solutions from both patient and surgeon perspectives. However, the translation of such technology into commercialization remains challenging. The lack of perception abilities is one of the obstructive factors paramount for a safe, accurate and efficient robot-assisted intervention. Integrating different types of miniature sensors onto robotic end-effectors is a promising trend to compensate for the perceptual deficiencies in soft robots. For example, haptic feedback with force sensors helps surgeons to control the interaction force at the tool-tissue interface, impedance sensing of tissue electrical properties can be used for tumor detection. The last decade has witnessed significant progress in the development of multimodal sensors built on the advancement in engineering, material science and scalable micromachining technologies. This review article provides a snapshot on common types of integrated sensors for soft medical robots. It covers various sensing mechanisms, examples for practical and clinical applications, standard manufacturing processes, as well as insights on emerging engineering routes for the fabrication of novel and high-performing sensing devices.

A profound investigation of the interaction mechanics between blood vessels and guidewires is necessary to achieve safe intervention. An interactive force model between guidewires and blood vessels is established based on cardiovascular fluid dynamics theory and contact mechanics, considering two intervention phases (straight intervention and contact intervention at a corner named "J-vessel"). The contributing factors of the force model, including intervention conditions, guidewire characteristics, and intravascular environment, are analyzed. A series of experiments were performed to validate the availability of the interactive force model and explore the effects of influential factors on intervention force. The intervention force data were collected using a 2-DOF mechanical testing system instrumented with a force sensor. The guidewire diameter and material were found to significantly impact the intervention force. Additionally, the intervention force was influenced by factors such as blood viscosity, blood vessel wall thickness, blood flow velocity, as well as the interventional velocity and interventional mode. The experiment of the intervention in a coronary artery physical vascular model confirms the practicality validation of the predicted force model and can provide an optimized interventional strategy for vascular interventional surgery. The enhanced intervention strategy has resulted in a considerable reduction of approximately 21.97 % in the force exerted on blood vessels, effectively minimizing the potential for complications associated with the interventional surgery.

Artificial intelligence (AI) ECG arrhythmia mapping provides arrhythmia source localization using 12-lead ECG data; whether this information impacts procedural efficiency is unknown. We performed a retrospective, case-control study to evaluate the hypothesis that AI ECG mapping may reduce time to ablation, procedural duration, and fluoroscopy.

Cases in which system output was used were retrospectively enrolled according to IRB-approved protocols at each site. Matched control cases were enrolled in reverse chronological order beginning on the last day for which the technology was unavailable. Controls were matched based upon physician, institution, arrhythmia, and a predetermined complexity rating. Procedural metrics, fluoroscopy data, and clinical outcomes were assessed from time-stamped medical records.

The study group consisted of 28 patients (age 65 ± 11 years, 46% female, left atrial dimension 4.1 ± 0.9 cm, LVEF 50 ± 18%) and was similar to 28 controls. The most common arrhythmia types were atrial fibrillation (n = 10), premature ventricular complexes (n = 8), and ventricular tachycardia (n = 6). Use of the system was associated with a 19.0% reduction in time to ablation (133 ± 48 vs. 165 ± 49 min, p = 0.02), a 22.6% reduction in procedure duration (233 ± 51 vs. 301 ± 83 min, p < 0.001), and a 43.7% reduction in fluoroscopy (18.7 ± 13.3 vs. 33.2 ± 18.0 min, p < 0.001) versus controls. At 6 months follow-up, arrhythmia-free survival was 73.5% in the study group and 63.3% in the control group (p = 0.56).

Use of forward-solution AI ECG mapping is associated with reductions in time to first ablation, procedure duration, and fluoroscopy without an adverse impact on procedure outcomes or complications.

In recent decades, diagnosing, risk-stratifying, and treating patients with primary electrical diseases, as well as heart rhythm disorders, have improved substantially [...].

Pulsed electric field (PEF) ablation relies on the intersection of a critical voltage gradient with tissue to cause cell death. Field-based lesion formation with PEF technologies may still depend on catheter-tissue contact (CTC). The purpose of this study was to assess the impact of CTC on PEF lesion formation with an investigational large area focal (LAF) catheter in a preclinical model.

PEF ablation via a 10-spline LAF catheter was used to create discrete right ventricle (RV) lesions and atrial lesion sets in 10 swine (eight acute, two chronic). Local impedance (LI) was used to assess CTC. Lesions were assigned to three cohorts using LI above baseline: no tissue contact (NTC: ≤∆10 Ω, close proximity to tissue), low tissue contact (LTC: ∆11-29 Ω), and high tissue contact (HTC: ≥∆30 Ω). Acute animals were infused with triphenyl tetrazolium chloride (TTC) and killed ≥2 h post-treatment. Chronic animals were remapped 30 days post-index procedure and stained with infused TTC.

Mean (± SD) RV treatment sizes between LTC (n = 14) and HTC (n = 17) lesions were not significantly different (depth: 5.65 ± 1.96 vs. 5.68 ± 2.05 mm, p = .999; width: 15.68 ± 5.22 vs. 16.98 ± 4.45 mm, p = .737), while mean treatment size for NTC lesions (n = 6) was significantly smaller (1.67 ± 1.16 mm depth, 5.97 ± 4.48 mm width, p < .05). For atrial lesion sets, acute and chronic conduction block were achieved with both LTC (N = 7) and HTC (N = 6), and NTC resulted in gaps.

PEF ablation with a specialized LAF catheter in a swine model is dependent on CTC. LI as an indicator of CTC may aid in the creation of consistent transmural lesions in PEF ablation.

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society, the Asia Pacific Heart Rhythm Society, and the Latin American Heart Rhythm Society .

Creating large lesion in ablations using the DiamondTemp (DTA) ablation system may reduce the frequency of arrhythmia recurrence and allow the treatment of ventricular arrhythmias. Therefore, this study aimed to investigate whether power, application time, contact force (CF), and contact angle affect lesion formation in the ventricles.

Ablations were delivered to porcine myocardial preps to evaluate the lesion characteristics. Ablations were conducted with a maximum power of 50 W, target temperature of 58°C, CF of 10, 20, or 30 g, and contact angle between the catheter tip and tissue. The ablation durations were 15, 30, 60 s, 15 s × 2, or 30 s × 2.

Steam pops occurred only in cases with perpendicular contact. The lesion depth was larger in all settings in the perpendicular orientation than in the parallel orientation. The temperatures were lower in all settings in the perpendicular orientation than in the parallel orientation. The lesions became larger as CF increased with perpendicular contact and duration of ≥30 s. The longer application time resulted in larger surface area, depth, and volume of the lesion. Lesion depth was greater with single application of 30 and 60 s than with 15 s × 2 and 30 s × 2, respectively.

It is important to perform a single prolonged application as much as possible to create deeper lesions. Parallel contact with the tissue should be maintained to take advantage of the temperature sensor's capabilities to avoid pop phenomenon.

Effects of contact force (CF) on lesion formation during pulsed field ablation (PFA) have not been well validated. The purpose of this study was to determine the relationship between average CF and lesion size during PFA using a swine-beating heart model.

A 7F catheter with a 3.5-mm ablation electrode and CF sensor (TactiCath SE, Abbott) was connected to a PFA system (CENTAURI, Galvanize Therapeutics). In 5 closed-chest swine, biphasic PFA current was delivered between the ablation electrode and a skin patch at 40 separate sites in right ventricle (28 Amp) and 55 separate sites in left ventricle (35 Amp) with 4 different levels of CF: (1) low (CF range of 4-13 g; median, 9.5 g); (2) moderate (15-30 g; median, 21.5 g); (3) high (34-55 g; median, 40 g); and (4) no electrode contact, 2 mm away from the endocardium. Swine were sacrificed at 2 hours after ablation, and lesion size was measured using triphenyl tetrazolium chloride staining. In 1 additional swine, COX (cytochrome c oxidase) staining was performed to examine mitochondrial activity to delineate reversible and irreversible lesion boundaries. Histological examination was performed with hematoxylin and eosin and Masson trichrome staining.

Ablation lesions were well demarcated with triphenyl tetrazolium chloride staining, showing (1) a dark central zone (contraction band necrosis and hemorrhage); (2) a pale zone (no mitochondrial activity and nuclear pyknosis, indicating apoptosis zone); and a hyperstained zone by triphenyl tetrazolium chloride and COX staining (unaffected normal myocardium with preserved mitochondrial activity, consistent with reversible zone). At constant PFA current intensity, lesion depth increased significantly with increasing CF. There were no detectable lesions resulting from ablation without electrode contact.

Acute PFA ventricular lesions show irreversible and reversible lesion boundaries by triphenyl tetrazolium chloride staining. Electrode-tissue contact is required for effective lesion formation during PFA. At the same PFA dose, lesion depth increases significantly with increasing CF.

Cryoballoon ablation, especially Arctic Front Advance Pro (AFA-Pro) (Medtronic, Minneapolis, Minnesota, USA), has been widely recognised as a standard approach to atrial fibrillation (AF). Recently, Boston Scientific has released a novel cryoballoon system (POLARx). Despite comparable acute clinical outcomes of these two cryoballoons, the recent study reported a higher complication rate, especially for phrenic nerve palsy, with POLARx. However, their impact on biological tissue remains unclear.

The purpose of our study is to evaluate temperature change of biological tissue during cryoablation of each cryoballoon using a porcine experimental model.

A tissue-based pulmonary vein model was constructed from porcine myocardial tissue and placed on a stage designed to simulate pulmonary vein anatomy and venous flow. Controlled cryoablations of AFA-Pro and POLARx were performed in this model to evaluate the tissue temperature. A temperature sensor was set behind the muscle and cryoballoon ablation was performed after confirming the occlusion of pulmonary vein with cryoballoon.

The mean tissue nadir temperature during cryoablation with AFA-Pro was -41.5°C±4.9°C, while the mean tissue nadir temperature during cryoablation with POLARx was -58.4°C±5.9°C (p<0.001). The mean balloon nadir temperature during cryoablation with AFA-Pro was -54.6°C±2.6°C and the mean balloon nadir temperature during cryoablation with POLARx was -64.7°C±3.8°C (p<0.001).

POLARx could freeze the biological tissue more strongly than AFA-Pro.

Ablation index (AI)-guided ablation improves the incidence of arrhythmia recurrence as compared to conventional contact force (CF)-guided ablation. The aim of this study was to elucidate the differences in the biomarkers associated with myocardial injury and inflammation between conventional CF-guided and AI-guided ablation.

Atrial fibrillation (AF) patients who underwent pulmonary vein isolation (PVI) from the Osaka Rosai Atrial Fibrillation ablation (ORAF) registry were enrolled. We divided the patients into two groups: conventional CF-guided PVI (CF group) and AI-guided PVI (AI group). The differences in biomarkers associated with myocardial injury and inflammation, and long-term durability of PVI between the two groups were evaluated.

This study population included a total of 794 patients (CF-guided, 241 patients; AI-guided, 553 patients). Total application time was significantly shorter, and total application number was significantly smaller in AI than CF group. High-sensitive troponin I (hs-TnI) post-ablation was significantly higher in AI than CF group (p < 0.001), even after taking the total application number and total application time into consideration. No significant differences in inflammatory markers changes from pre- to post-ablation were observed between the two groups. AI-guided ablation was significantly associated with the hs-TnI post-ablation by multiple regression analysis. The PV reconnection ratio was significantly smaller in AI than CF group (p = 0.037).

AI-guided ablation had the ability to create larger lesions than CF-guided ablation despite no increase in inflammation and achieved the better PVI durability than that of CF-guided.

Thermal ablation of tumors aims to apply extreme temperatures inside the target tissue to achieve substantial tumor destruction in a minimally invasive manner. Several techniques are comprised, classified according to the type of energy source. However, the lack of treatment selectivity still needs to be addressed, potentially causing two risks: i) incomplete tumor destruction and recurrence, or conversely, ii) damage of the surrounding healthy tissue. Therefore, the research herein reviewed seeks to develop sensing systems based on fiber Bragg gratings (FBGs) for thermal monitoring inside the lesion during radiofrequency, laser, and microwave ablation. This review shows that, mainly thanks to multiplexing and minimal invasiveness, FBGs provide an optimal sensing solution. Their temperature measurements are the feedback to control the ablation process and allow to investigate different treatments, compare their outcomes, and quantify the impact of factors such as proximity to thermal probe and blood vessels, perfusion, and tissue type.

Catheter ablation of ventricular arrhythmias (VAs) has evolved significantly over the past decade and is currently a well-established therapeutic option. Technological advances and improved understanding of VA mechanisms have led to tremendous innovations in VA ablation. The purpose of this review article is to provide an overview of current innovations in VA ablation. Mapping techniques, such as ultra-high density mapping, isochronal late activation mapping, and ripple mapping, have provided improved arrhythmogenic substrate delineation and potential procedural success while limiting duration of ablation procedure and potential hemodynamic compromise. Besides, more advanced mapping and ablation techniques such as epicardial and intramyocardial ablation approaches have allowed operators to more precisely target arrhythmogenic substrate. Moreover, advances in alternate energy sources, such as electroporation, as well as stereotactic radiation therapy have been proposed to be effective and safe. New catheters, such as the lattice and the saline-enhanced radiofrequency catheters, have been designed to provide deeper and more durable tissue ablation lesions compared to conventional catheters. Contact force optimization and baseline impedance modulation are important tools to optimize VT radiofrequency ablation and improve procedural success. Furthermore, advances in cardiac imaging, specifically cardiac MRI, have great potential in identifying arrhythmogenic substrate and evaluating ablation success. Overall, VA ablation has undergone significant advances over the past years. Innovations in VA mapping techniques, alternate energy source, new catheters, and utilization of cardiac imaging have great potential to improve overall procedural safety, hemodynamic stability, and procedural success.

The use of contact force (CF) sensing catheters has provided a revolutionary improvement in catheter ablation (CA) of atrial fibrillation (AF) in the past decade. However, the success rate of CA for AF remains limited, and some complications still occur.

The TRUEFORCE trial (Catheter Ablation of Atrial Fibrillation using FireMagic TrueForce Ablation Catheter) is a multicenter, prospective, single-arm objective performance criteria study of AF patients who underwent their first CA procedure using FireMagic TrueForce ablation catheter.

A total of 120 patients (118 with paroxysmal AF) were included in this study, and 112 patients included in the per-protocol analysis. Pulmonary vein isolation (PVI) was achieved in 100% of the patients, with procedure and fluoroscopy time of 146.63 ± 40.51 min and 12.89 ± 5.59 min, respectively. Freedom from recurrent atrial arrhythmia after ablation was present 81.25% (95% confidence interval [CI]: 72.78%-88.00%) of patients. No severe adverse events (death, stroke/transient ischemic attack [TIA], esophageal fistula, myocardial infarction, thromboembolism, or pulmonary vein stenosis) were detected during the follow-up. Four (4/115, 3.33%) adverse events were documented, including one abdominal discomfort, one femoral artery hematoma, one coughing up blood, and one postoperative palpitation and insomnia.

This study demonstrated the clinical feasibility of FireMagic force-sensing ablation catheter in CA of AF, with a satisfactory short- and long-term efficacy and safety.

Contact force (CF) is a novel approach developed to increase the safety and efficacy of catheter ablation. However, the value of CF-sensing technology for atrial flutter (AFL) cavo-tricuspid isthmus ablation (CTIA) is inconclusive. To generate a comprehensive assessment of optimal extant data on CF for AFL, we synthesized randomized controlled trials (RCTs) and observational studies from Web of Science, SCOPUS, EMBASE, PubMed, and Cochrane until 29 November 2022, using the odds ratio (OR) for dichotomous outcomes and mean difference (MD) for continuous outcomes with a corresponding 95% confidence interval (CI). Two RCTs and three observational studies with a total of 376 patients were included in our analysis. CF-guided ablation was associated with (A) a higher rate of AFL recurrence (OR: 2.26 with 95% CI [1.05, 4.87]) and total CF (MD: 2.71 with 95% CI [1.28, 4.13]); (B) no effect on total procedure duration (MD: -2.88 with 95% CI [-7.48, 1.72]), fluoroscopy duration (MD: -0.96 with 95% CI [-2.24, 0.31]), and bidirectional isthmus block (BDIB) (OR: 1.50 with 95% CI [0.72, 3.11]); and (C) decreased radiofrequency (RF) duration (MD: -1.40 with 95% CI [-2.39, -0.41]). We conclude that although CF-guided CTIA was associated with increased AFL recurrence and total CF and reduced RF duration, it did not affect total procedure duration, fluoroscopy duration, or BDIB. Thus, CF-guided CTIA may not be the optimal intervention for AFL. These findings indicate the need for (A) providers to balance the benefits and risks of CF when utilizing precision medicine to develop treatment plans for individuals with AFL and (B) clinical trials investigating CF-guided catheter ablation for AFL to provide definitive evidence of optimal CF-sensing technology.