Evaluation of ablation catheter technology: Comparison between thigh preparation model and an in vivo beating heart

Thermal Profiles for Focal Pulsed Electric Field Ablation

BACKGROUND

Pulsed electrical field (PEF) ablation may cause tissue heating. These changes are reportedly small, but each PEF system and waveform will have a different behavior, and data are lacking.

OBJECTIVES

This study sought to compare the temperature profile of focal point, monopolar biphasic PEF ablation versus radiofrequency (RF).

METHODS

Ablation lesions were performed on perfused thigh muscle of swine. PEF lesions were performed with 3 compatible ablation catheters at the highest (25 amp) energy, and 1 catheter (Tacticath SE) was also used at the 22- and 19-amp levels. Temperature changes in the tissue were measured using fluoroptic temperature probes inserted at the muscle surface, as well as 3 mm and 7 mm below the surface. Temperatures were recorded continuously at baseline, during delivery, and after ablation. Muscle temperatures were compared with those of RF lesions performed with 1 catheter (Tacticath SE) at 30 W for 30 seconds.

RESULTS

PEF ablation with 3energy settings produced small temperature changes. Maximum average temperature rise for PEF for the maximum (25-amp) energy setting (32 lesions) was 7.6 °C, 2.8 °C, and 0.9 °C at the surface, 3-mm depth, and 7-mm depth, respectively. The temperature rise was dose dependent, with lower energy settings yielding less temperature rise. RF ablations (10 lesions) produced temperature increases of 16.6 °C, 39.8 °C, and 9.5 °C at the surface, 3-mm depth, and 7-mm depth, respectively.

CONCLUSIONS

PEF caused detectable temperature changes in muscle tissue, which never exceeded 2.8 °C at the 3-mm depth versus baseline. By contrast, RF produced substantial temperature rises. These data support that focal monopolar biphasic energy delivered by this PEF technology retains a favorable thermal safety profile.

Utility and Limitations of Ablation Index for Guiding Therapy in Ventricular Myocardium

BACKGROUND

Ablation index (AI) is used for guiding therapy during pulmonary vein isolation. However, its potential utility in ventricular myocardium is unknown.

OBJECTIVES

This study sought to examine the correlation between AI and lesion dimensions in healthy and infarcted ventricles.

METHODS

In ex vivo experiments using healthy swine ventricles, the correlation between AI (400-1,200) and lesion dimensions was examined at fixed power (30 W) and contact force (CF) (15 g). To examine the accuracy of AI in predicting lesion dimensions created by different combinations of ablation parameters, applications with a similar prespecified AI value created using different power (30 vs 40 W), CF (15 vs 25 g) or impedance (130-170 Ω) were created. In in vivo experiments, the correlation between AI and lesion dimensions was examined in healthy and infarcted myocardium.

RESULTS

Ex vivo experiments (247 lesions, 36 hearts) showed good correlation between AI and lesion depth (R = 0.93; P < 0.001). However, in vivo experiments (9 healthy swine and 10 infarcted swine) showed moderate correlation in healthy myocardium (R = 0.64; P < 0.01) and poor correlation in infarcted myocardium (R = 0.23; P = 0.61). AI values achieved using different combinations of power, CF, and baseline impedance resulted in different lesion depths: Ablation at 30 W produced deeper lesions compared with 40 W, ablation with CF of 15 g produced deeper lesions compared with CF of 25 g, and ablation at lower impedance produced larger lesions at similar prespecified AI values (P < 0.01 for all).

CONCLUSIONS

AI has limited value for guiding ablation in ventricular myocardium, particularly scar. This may be related to small proportional significance of application duration and complex tissue architecture.

Development of a clinically relevant ex vivo model of cardiac ablation for testing of ablation catheters

INTRODUCTION

Reliable ex vivo cardiac ablation models have the potential to increase catheter testing throughput while minimizing animal usage. The goal of this work was to develop a physiologically relevant ex vivo swine model of cardiac ablation displaying minimal variability and high repeatability and identify and optimize key parameters involved in ablation outcomes.

METHODS AND RESULTS

A root cause analysis was conducted to identify variables affecting ablation outcomes. Parameters associated with the tissue, bath media, and impedance were identified. Variables were defined experimentally and/or from literature sources to best mimic the clinical cardiac ablation setting. The model was validated by performing three independent replicates of ex vivo myocardial ablation and a direct comparison of lesion outcomes of the ex vivo swine myocardial and in vivo canine thigh preparation (TP) models. Replicate experiments on the ex vivo model demonstrated low variance in ablation depth (6.5 ± 0.6, 6.3 ± 0.6, 6.2 ± 0.4 mm) and width (10.4 ± 1.1, 9.7 ± 1.0, 9.9 ± 0.9 mm) and no significant differences between replicates. In a direct comparison of the two models, the ex vivo model demonstrated ablation depths similar to the canine TP model at 35 W (6.9 ± 1.0, and 7.0 ± 0.9 mm) and 50 W (8.0 ± 0.7, and 8.4 ± 0.7 mm), as well as similar power to depth ratios (15% and 19% for the ex vivo cardiac and in vivo TP models, respectively).

CONCLUSION

The ex vivo model exhibited strong lesion reproducibility and power-to-depth ratios comparable to the in vivo TP model. The optimized ex vivo model minimizes animal usage with increased throughput, lesion characteristics similar to the in vivo TP model, and ability to discriminate minor variations between different catheter designs.

Characteristics of pulsed electric field cardiac ablation porcine treatment zones with a focal catheter

OBJECTIVES

Pulsed electric field (PEF) therapies employ punctuated energy delivery to kill cells in a volume of tissue through mechanisms that are not dependent on thermal processes. A key component to successful cardiac ablation procedures is ensuring the generation of transmural, contiguous ablation zones, which requires in-depth knowledge regarding treatment sizes for a given therapeutic application.

METHODS

In this study, a series of acute treatments were delivered to porcine ventricles, where triphenyl tetrazolium chloride (TTC) vitality stain was used to identify treatment effect sizes for the three focal monopolar CENTAURI PEF cardiac ablation energy settings.

RESULTS

Treatment depths were 5.7, 7.2, and 8.2 mm for the 19, 22, and 25 A energy settings, respectively. Gross pathology indicated umbral zones of hemorrhage surrounded by pale avital TTC-negative-negative tissue, which contrasted significantly from radiofrequency ablation (RF) controls. Histologically, treatment zones are identified by regions of contraction band necrosis and cardiomyocytolysis, which contrasted with RF control lesions composed primarily of coagulation necrosis.

CONCLUSIONS

Together, these data indicate the ability for focal monopolar PEF treatments to generate deep treatment zones in cardiac ablation without incurring the gross or histological coagulative characteristics of RF thermal lesions.

Characterization of high-power and very-high-power short-duration radiofrequency lesions performed with a new-generation catheter and a temperature-control ablation mode

INTRODUCTION

High-power short-duration (HPSD) has been proposed to shorten procedure times while maintaining efficacy and safety. We evaluated the differences in size and geometry between radiofrequency lesions obtained with this method and conventional ones.

METHODS AND RESULTS

Twenty-eight sets of 10 perpendicular radiofrequency applications were performed with two commercially available catheters: a temperature-controlled HPSD catheter (QDot-Micro) and a conventional power-controlled catheter (Thermocool SmartTouch) on porcine left ventricle. Different power settings (35, 40, 50, and 90 W), contact force (CF; 10 and 20 g), ablation index (AI; 400 and 550), and application times were combined to create conventional (35-40 W), HPSD (50 W) and very-high-power short-duration (VHPSD; 90 W) lesions, that were cross-sectioned and measured. About 4-s VHPSD lesions were smaller, shallower, and thinner than HPSD performed with the QDot-Micro catheter in any scenario of CF or AI (61 ± 7.8 mm³ , 6.1 ± 0.3 mm wide, and 2.9 ± 0.1 mm deep with 10 g; 72.2 ± 0.5 mm³ , 6.8 ± 0.3 mm wide, and 2.9 ± 0.2 mm deep with 20 g). Conventional and HPSD lesions performed with the temperature-controlled catheter were generally bigger, deeper, and wider than the ones obtained with the power-controlled catheter, as well as more consistent in size. This was especially true with the lower CF and AI scenario, while differences were less notable with other setting combinations.

CONCLUSION

VHPSD lesions performed with QDot-Micro catheter were smaller than any other lesions, which is especially attractive for posterior left atrial wall ablation. On the contrary, conventional-powered and HPSD lesions performed with this catheter were equally sized (or even bigger with lower CF and AI objectives), as well as more consistent in size, which would guarantee transmurality in other locations.

In-Silico Modeling to Compare Radiofrequency-Induced Thermal Lesions Created on Myocardium and Thigh Muscle

Beating heart (BH) and thigh muscle (TM) are two pre-clinical models aimed at studying the lesion sizes created by radiofrequency (RF) catheters in cardiac ablation. Previous experimental results have shown that thermal lesions created in the TM are slightly bigger than in the BH. Our objective was to use in-silico modeling to elucidate some of the causes of this difference. In-silico RF ablation models were created using the Arrhenius function to estimate lesion size under different energy settings (25 W/20 s, 50 W/6 s and 90 W/4 s) and parallel, 45° and perpendicular catheter positions. The models consisted of homogeneous tissue: myocardium in the BH model and striated muscle in the TM model. The computer results showed that the lesion sizes were generally bigger in the TM model and the differences depended on the energy setting, with hardly any differences at 90 W/4 s but with differences of 1 mm in depth and 1.5 m in width at 25 W/20 s. The higher electrical conductivity of striated muscle (0.446 S/m) than that of the myocardium (0.281 S/m) is possibly one of the causes of the higher percentage of RF energy delivered to the tissue in the TM model, with differences between models of 2–5% at 90 W/4 s, ~9% at 50 W/6 s and ~10% at 25 W/20 s. Proximity to the air–blood interface (just 2 cm from the tissue surface) artificially created in the TM model to emulate the cardiac cavity had little effect on lesion size. In conclusion, the TM-based experimental model creates fairly similar-sized lesions to the BH model, especially in high-power short-duration ablations (50 W/6 s and 90 W/4 s). Our computer results suggest that the higher electrical conductivity of striated muscle could be one of the causes of the slightly larger lesions in the TM model.

Increasing Lesion Dimensions of Bipolar Ablation by Modulating the Surface Area of the Return Electrode

OBJECTIVES

This study sought to examine the effect of the return electrode's surface area on bipolar RFA lesion size.

BACKGROUND

Bipolar radiofrequency ablation (RFA) is typically performed between 2 3.5-mm tip catheters serving as active and return electrodes. We hypothesized that increasing the surface area of the return electrode would increase lesion dimensions by reducing the circuit impedance, thus increasing the current into a larger tissue volume enclosed between the electrodes.

METHODS

In step 1, ex vivo bipolar RFA was performed between 3.5-mm and custom-made return electrodes with increasing surface areas (20, 80, 180 mm²). In step 2, ex vivo bipolar RFA was performed between 3.5-mm and 3.5-mm or 8-mm electrode catheters positioned perpendicular or parallel to the tissue. In step 3, in vivo bipolar RFA was performed between 3.5-mm and either 3.5-mm or 8-mm parallel electrode at the: 1) left ventricular summit; 2) interventricular septum; and 3) healed anterior infarction.

RESULTS

In step 1, increasing the surface area of the return electrode resulted in lower circuit impedance (R = -0.65; P < 0.001), higher current (R = +0.80; P < 0.001), and larger lesion volume (R = +0.88; P < 0.001). In step 2, an 8-mm return electrode parallel to tissue produced larger and deeper lesions compared with a 3.5-mm return electrode (P = 0.014 and P = 0.02). Similarly, in step 3, compared with a 3.5-mm, bipolar RFA with an 8-mm return electrode produced larger (volume: 1,525 ± 871 mm³ vs 306 ± 310 mm³, respectively; P < 0.001) and more transmural lesions (88% vs 0%; P < 0.001).

CONCLUSIONS

Bipolar RFA using an 8-mm return electrode positioned parallel to the tissue produces larger lesions in comparison with a 3.5-mm return electrode.

Optimizing Durability in Radiofrequency Ablation of Atrial Fibrillation

Radiofrequency ablation (RFA) remains a highly effective therapy in the management of paroxysmal atrial fibrillation (PAF) and is an important therapeutic option in the management of persistent atrial fibrillation (PeAF) when clinically indicated. Lesion size is influenced by many parameters, which include those related to energy application (RFA power, temperature, and time), delivery mechanism (electrode size, orientation, and contact force), and the environment (blood flow and local tissue contact, stability, and local impedance). Successful durable RFA is dependent on achieving lesions that are reliably transmural and contiguous, whilst also avoiding injury to the surrounding structures. This review focuses on the variables that can be adjusted in connection with RFA to achieve long-lasting lesions that enable patients to derive the maximum sustained benefit from pulmonary vein isolation and additional lesion sets if utilized.

Impact of catheter-tissue contact force on lesion size during right ventricular outflow tract ablation in a swine model

Background

The catheter-tissue contact force (CF) is one of the significant determinants of lesion size and thus has a considerable impact on the effectiveness of ablation procedures. This study aimed to evaluate the impact of CF on the lesion size during right ventricular outflow tract (RVOT) ablation in a swine model.

Methods

Twelve Guangxi Bama miniature male pigs weighing 40 to 50 kg were studied. After general anesthesia, a ThermoCool SmartTouch contact-sensing ablation catheter was introduced to the RVOT via the femoral vein under the guidance of the CARTO 3 system. The local ventricular voltage amplitude and impedance were measured using different CF levels. We randomly divided the animals into the following four groups according to the different CF levels: group A (3–9 g); group B (10–19 g); group C (20–29 g); and group D (30–39 g). Radiofrequency ablations were performed at three points in the free wall and septum of the RVOT in power control mode at 30 W for 30 s while maintaining the saline irrigation rate at 17 mL/min. At the end of the procedures, the maximum depth, surface diameter, and lesion volume were measured and recorded. A linear regression analysis was performed to determine the relationship between continuous variables.

Results

A total of 72 ablation lesions were created in the RVOT of the 12 Bama pigs. The maximum depth, surface diameter, and volume of the lesions measured were well correlated with the CF (free wall: β = 0.105, β = 0.162, β = 3.355, respectively, P < 0.001; septum: β = 0.093, β = 0.150, β = 3.712, respectively, P < 0.001). The regional ventricular bipolar voltage amplitude, unipolar voltage amplitude, and impedance were weakly positively associated with the CF (β = 0.065, β = 0.125, and β = 1.054, respectively, P < 0.001). There was a significant difference in the incidence of steam pops among groups A, B, C, and D (free wall: F = 7.3, P = 0.032; septum: F = 10.5, P = 0.009); and steam pops occurred only when the CF exceeded 20 g. Trans-mural lesions were observed when the CF exceeded 10 g in the free wall, while the lesions in the septum were non-trans-mural even though the CF reached 30 g.

Conclusions

CF seems to be a leading predictive factor for the size of formed lesions in RVOT ablation. Maintaining the CF value between 3 and 10 g may be reasonable and effective for creating the necessary lesion size and reducing the risk of complications, such as steam pops and perforations.

Expandable Lattice Electrode Ablation Catheter: A Novel Radiofrequency Platform Allowing High Current at Low Density for Rapid, Titratable, and Durable Lesions

BACKGROUND

High-current short-duration radiofrequency energy delivery has potential advantages for cardiac ablation. However, this strategy is limited by high current density and narrow safety-to-efficacy window. The objective of this study was to examine a novel strategy for radiofrequency energy delivery using a new electrode design capable of delivering high power at a low current density to increase the therapeutic range of radiofrequency ablation.

METHODS

The Sphere9 is an expandable spheroid-shaped lattice electrode design with an effective surface area 10-fold larger than standard irrigated electrodes (lattice catheter). It incorporates 9 surface temperature sensors with ablation performed in a temperature-controlled mode. Phase I: in 6 thigh muscle preparations, 2 energy settings for atrial ablation were compared between the lattice and irrigated-tip catheters (low-energy: T_max75°C/5 s versus 25 W/20 s; high-energy: T_max75°C/7 s versus 30 W/20 s). Phase II: in 8 swine, right atrial lines were created in the posterior and lateral walls using low- and high-energy settings, respectively. Phase III: the safety, efficacy, and durability at 30 days were evaluated by electroanatomical mapping and histopathologic analysis.

RESULTS

In the thigh model, the lattice catheter resulted in wider lesions at both low- and high-energy settings (18.7±3.3 versus 12.2±1.7 mm, P<0.0001; 19.4±2.4 versus 12.3±1.7 mm, P<0.0001). Atrial lines created with the lattice were wider (posterior: 14.7±3.4 versus 9.2±4.0 mm, P<0.0001; lateral: 15.8±4.2 versus 5.7±4.2 mm, P<0.0001) and required 85% shorter ablation time (12.4 versus 79.8 s/cm-line). While current squared (I²) was higher with Sphere9 (7.0±0.04 versus 0.2±0.002 A²; P<0.0001), the current density was lower (9.6±0.9 versus 16.9±0.09 mA/mm²; P<0.0001). At 30 days, 100% of ablation lines created with the lattice catheter remained contiguous compared with only 14.3% lines created with a standard irrigated catheter. This was achieved without steam pops or collateral tissue damage.

CONCLUSIONS

In this preclinical model, a novel, high-current low-density radiofrequency ablation strategy created contiguous and durable ablation lines in significantly less ablation time and a comparable safety profile.

Lesion Index Titration Using Contact-Force Technology Enables Safe and Effective Radiofrequency Lesion Creation at the Root of the Aorta and Pulmonary Artery

BACKGROUND

Ablation of some myocardial substrates requires catheter-based radiofrequency delivery at the root of a great artery. We studied the safety and efficacy parameters associated with catheter-based radiofrequency delivery at the root of the aorta and pulmonary artery.

METHODS

Thirty-six pigs underwent in-vivo catheter-based ablation under continuous contact-force and lesion index (power, contact-force, and time) monitoring during 60-s radiofrequency delivery with an open-irrigated tip catheter. Twenty-eight animals were allocated to groups receiving 40 W (n=9), 50 W (n=10), or 60 W (n=9) radiofrequency energy, and acute (n=22) and chronic (n=6) arterial wall damage was quantified by multiphoton microscopy in ex vivo samples. Adjacent myocardial lesions were quantified in parallel samples. The remaining 8 pigs were used to validate safety and efficacy parameters.

RESULTS

Acute collagen and elastin alterations were significantly associated with radiofrequency power, although chronic assessment revealed vascular wall recovery in lesions without steam pop. The main parameters associated with steam pops were median peak temperature >42°C and impedance falls >23 ohms. Unlike other parameters, lesion index values of 9.1 units (interquartile range, 8.7-9.8) were associated with the presence of adjacent myocardial lesions in both univariate ( P=0.03) and multivariate analyses ( P=0.049; odds ratio, 1.99; 95% CI, 1.02-3.98). In the validation group, lesion index values using 40 W over a range of contact-forces correlated with the size of radiofrequency lesions (R²=0.57; P=0.03), with no angiographic or histopathologic signs of coronary artery damage.

CONCLUSIONS

Lesion index values obtained during 40 W radiofrequency applications reliably monitor safe and effective lesion creation at the root of the great arteries.

Temperature-Controlled Radiofrequency Ablation Using Irrigated Catheters: Maximizing Ventricular Lesion Dimensions While Reducing Steam-Pop Formation

OBJECTIVES

The goal of this study was to examine the safety and efficacy of radiofrequency ablation (RFA) with irrigated catheters operated in a temperature-controlled mode for ventricular ablation.

BACKGROUND

Techniques to increase RFA dimensions are associated with higher risk for steam-pops. A novel irrigated catheter with circumferential thermocouples embedded in its ablation surface provides real-time surface temperature data. This study hypothesized that RFA operated in a temperature-controlled mode may allow maximizing lesion dimensions while reducing the occurrence of steam-pops.

METHODS

RFA with an irrigated catheter incorporating surface thermocouples was examined in 6 swine thigh muscle preparations and 15 beating ventricles at higher (50 W/60 s, T_max50^oC) and lower (50 W/60 s, T_max45^oC) temperature limits. Biophysical properties, lesion dimensions, and steam-pop occurrence were compared versus RFA with a standard catheter operated in power-control mode at higher (50 W/60 s) and lower (40W/60 s) power, and additionally at high power with half-normal saline (50 W/60 s).

RESULTS

In the thigh muscle preparation, lesion depth and width were similar between all groups (p = 0.90 and p = 0.17, respectively). Steam-pops were most frequent with power-controlled ablation at 50 W/60 s (82%) and least frequent with temperature-controlled ablation at 50 W/60 s, T_max45^oC (0%; p < 0.001). In the beating ventricle, lesion depth was comparable between all RFA settings (p = 0.09). Steam-pops were most frequent using power-controlled ablation at 50 W/60 s (37%) and least frequent with temperature-controlled ablation at 50 W/60 s, T_max45^oC (7%; p < 0.001). Half-normal saline had no incremental effect on lesion dimensions at 50 W in either the thigh muscle or the beating heart.

CONCLUSIONS

RFA using a novel irrigated catheter with surface thermocouples operated in a temperature-controlled mode can maximize lesion dimensions while reducing the risk for steam-pops.

Preliminary Validation of Electroporation-Electrolysis (E2) for Cardiac Ablation Using a Parameterisable In-Vivo Model

Atrial fibrillation is the most common arrhythmia, increasing the risk of stroke, heart failure and death, and a growing epidemic. Electroporation ablation is emerging in cardiac ablation for atrial fibrillation as a fast, tissue-specific and non-thermal alternative to existing technologies tied by their thermal action to shortcomings in efficacy, speed and risk. Studies so far have aimed to translate the success of irreversible electroporation from tumour treatment, with its kilovolt pulses, to cardiac ablation. However, these high voltages may be less appealing for cardiac ablation from clinical, technical and regulatory standpoints. A novel ablation technique combining electroporation and electrolysis in a single pulse E2 uses lower voltages. A custom E2 ablation system was developed and tested on an in vivo tissue model. Histopathological analysis showed lesions of clinically relevant depth, achieved without any acute complications or severe muscle contractions. Lesions were mapped onto a numerical model developed to refine further prototyping. This study provides preliminary prototype validation and the methodological foundation for dose optimisation towards endocardial application.

Histology Strategies for Medical Implants and Interventional Device Studies

Histology of medical devices poses a variety of unique challenges. Comprehensive histologic assessment of medical devices often requires spatial context and high-quality retention of the device–tissue interface. However, the composition of many medical devices is often not amenable to traditional paraffin embedding and thus alternative specialized methodologies such as hard resin embedding must be used. Hard resin embedding requires specialized laboratory technical expertise and equipment, and the fixation techniques and resin composition used markedly impact the feasibility of immunohistochemistry. For the continuity of spatial context during histologic evaluation, additional imaging methods such as macrophotography, radiography, micro-Computerized Tomography (microCT), or magnetic resonance imaging (MRI) can be used to guide sectioning and to complement histologic findings. Although standardized approaches are scarce for medical devices, important considerations specific to medical device histology are discussed, including general specimen preparation, special considerations for devices by organ system, and the challenges of immunohistochemistry. Histologic preparation of medical devices must be thoughtful, thorough, and tailored to achieve optimal histologic outcomes for complex, valuable, and often limited implant specimens.

High-Power and Short-Duration Ablation for Pulmonary Vein Isolation: Biophysical Characterization

OBJECTIVES

This study sought to examine the biophysical properties of high-power and short-duration (HP-SD) radiofrequency ablation for pulmonary vein isolation.

BACKGROUND

Pulmonary vein isolation is the cornerstone of atrial fibrillation ablation. However, pulmonary vein reconnection is frequent and is often the result of catheter instability, tissue edema, and a reversible nontransmural injury. We postulated that HP-SD ablation increases lesion-to-lesion uniformity and transmurality.

METHODS

This study included 20 swine and a novel open-irrigated ablation catheter with a thermocouple system able to record temperature at the catheter-tissue interface (QDOT Micro Catheter). Step 1 compared 3 HP-SD ablation settings: 90 W/4 s, 90 W/6 s, and 70 W/8 s in a thigh muscle preparation. Ablation at 90 W/4 s was identified as the best compromise between lesion size and safety parameters, with no steam-pop or char. In step 2, a total of 174 single ablation applications were performed in the beating heart and resulted in 3 (1.7%) steam-pops, all occurring at catheter-tissue interface temperature ≥85°C. Additional 233 applications at 90 W/4 s and temperature limit of 65°C were applied without steam-pop. Step 3 compared the presence of gaps and lesion transmurality in atrial lines and pulmonary vein isolation between HP-SD (90 W/4 s, T ≤65°C) and standard (25 W/20 s) ablation.

RESULTS

HP-SD ablation resulted in 100% contiguous lines with all transmural lesions, whereas standard ablation had linear gaps in 25% and partial thickness lesions in 29%. Ablation with HP-SD produced wider lesions (6.02 ± 0.2 mm vs. 4.43 ± 1.0 mm; p = 0.003) at similar depth (3.58 ± 0.3 mm vs. 3.53 ± 0.6 mm; p = 0.81) and improved lesion-to-lesion uniformity with comparable safety end points.

CONCLUSIONS

In a preclinical model, HP-SD ablation (90 W/4 s, T ≤65°C) produced an improved lesion-to-lesion uniformity, linear contiguity, and transmurality at a similar safety profile of conventional ablation.