B-PO02-033 MECHANISM TISSUE HEATING DURING HIGH-POWER SHORT-DURATION ABLATION VS. 30W-SETTING ABLATION: IN VIVO ACTUAL TISSUE TEMPERATURE

Background - With short radiofrequency (RF) applications, tissue temperature continues to rise after RF-termination ("thermal latency"), which may result in lesion growth after RF-termination. The purpose was to compare in-vivo tissue temperature profile (thermal latency), lesion size and the incidence of steam pop and thrombus between RF-ablation with very-high-power-very-short-RF(90W/4s), high-power-short-RF(50W/10s) and moderate-power-moderate-RF(30W/30s) in a canine thigh muscle preparation and beating heart. Methods - In the thigh muscle preparation (5dogs), a 3.5mm ablation-electrode with 66 or 56 small irrigation holes (QDOT-Micro or ThermoCoolSmartTouch-SF, respectively) was held perpendicular or parallel to the muscle at 10 or 30g contact force (CF). Total of 120RFs were delivered at 90W/4s(QDOT-catheter), 50W/10s or 30W/30s(SF-catheter). Electrode temperature, electrode-tissue-interface temperature and tissue temperatures at 3mm and 7mm-depths were measured. In 6 closed-chest dogs, total of 72RFs were delivered in the ventricle at 90W/4s, 50W/10s or 30W/30s. Results - In the thigh muscle preparation, tissue temperatures and lesion size (depth, diameter and volume) were lowest/smallest for RFs at 90W/4s, followed by 50W/10s and greatest for 30W/30s. Thermal latency (Δtemperature and duration) was greatest for RFs at 90W/4s, followed by 50W/10s and smallest for 30W/30s ( p <0.01). Effective tissue heating (area under curve≥50°C at 3mm-depth) was observed after RF-termination in 88.0±7.6% with 90W/4s, 57.7±14.6% with 50W/10s, and only 31.9±8.5% with 30W/30s ( p <0.01). In beating hearts, lesion size was also smallest with 90W/4s and greatest with 30W/30s RFs. Increasing CF significantly increased lesion depth in all three groups. There was no significant difference in the incidence of steam pop or thrombus between three groups. Conclusions - Tissue temperatures and lesion size (depth, diameter and volume) were lowest/smallest for RF-applications at 90W/4s, followed by 50W/10s and greatest for 30W/30s. The greater thermal latency for 90W/4s RF-applications suggests that a significant portion of lesion is created after RF-termination due to conductive tissue heating.

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Spatial Thermodynamics of very High Power-Short Duration Catheter Ablation for Pulmonary Vein Isolation in an in-vivo model

10.22541/au.162065770.06236007/v1 ◽

2021 ◽

Author(s):

Atsushi Suzuki ◽

H. Immo Lehmann ◽

Songyun Wang ◽

Kay Parker ◽

Kristi Monahan ◽

...

Keyword(s):

Catheter Ablation ◽

Pulmonary Vein ◽

Short Duration ◽

Pulmonary Vein Isolation ◽

Contact Force ◽

High Power ◽

Tissue Temperature ◽

In Vivo Model ◽

Very High

Introduction: The spatial thermodynamics of very high power-short duration (vHPSD) radiofrequency (RF) application during pulmonary vein isolation (PVI) in in-vivo model has not been well characterized. This study was conducted to investigate the distance-temperature relationship during vHPSD-RF ablation. Methods: PVI was performed using the vHPSD catheter with the settings of 90W, RF time of 4 sec and 15mL/min irrigation in a canine model. Catheter contact force (CF) of 10-20g was defined as ‘normal’ and CF >20g as ‘firm’ CF. Tissue temperature was monitored using thermocouples implanted at the surface of the left atrial-pulmonary vein junction, left phrenic nerve, and the luminal esophagus. PVI using a standard contact-force sensing catheter (SCF) (settings of 35W, 30sec and 30mL/min irrigation) was performed for comparison. Results: A total of 334 TC profiles in 4 animals was investigated. Time to maximum tissue temperature (MTT) (6.0sec [vHPSD/normal CF] vs. 30.5 sec [SCF/normal CF], p<0.001; 8.0sec [vHPSD/firm CF] vs. 24.0sec [SCF/firm CF], p=0.022) was shorter with vHPSD than in SCF groups. MTT within 10mm from catheter-tip was lower in vHPSD ablation with normal CF than using SCF ablation (median 41.9°C [interquartile-range; 40.2-46.1] vs. 49.5°C [45.9-56.2], p=0.013). The distance margin to keep the MTT below 39ºC, 42ºC, and 50ºC were 4.9mm, 4.2mm, and 3.4mm, respectively in the vHPDS group. This margin was larger (8.0mm, 6.6mm, and 4.6mm) in the SCF group. Conclusion: Our study underscores that vHPSD creates greater resistive heating than conventional catheter ablation.

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1319Local impedance on a force sensing catheter predicts volumetric lesion temperature changes

EP Europace ◽

10.1093/europace/euaa162.248 ◽

2020 ◽

Vol 22 (Supplement_1) ◽

Author(s):

K Garrott ◽

A Gams ◽

J Laughner ◽

L Lehn ◽

S Gutbrod ◽

...

Keyword(s):

Temperature Profile ◽

High Power ◽

Characteristic Temperature ◽

Tissue Temperature ◽

Maximum Temperature ◽

Rf Ablation ◽

Volumetric Heating ◽

Tissue Heating ◽

Tissue Surface

Abstract Funding Acknowledgements Study was funded by Boston Scientific The effective delivery of RF energy is dependent on transmural tissue heating, with irreversible tissue necrosis occurring at a tissue temperature ≥ 50°C. While multi-input lesion indexing algorithms can provide some value in predicting lesion durability, no clinically available metric measures tissue heating under the endocardial surface. Temperature measured from the catheter at the tissue surface is a surrogate for intra-lesion heating, but variables such as intra-cardiac flow and catheter irrigation have the potential to make this measure unreliable. A metric that assesses volumetric tissue heating would provide a superior method of predicting RF ablation in clinical practice. This study evaluated a prototype catheter that measures local catheter impedance (LI) using ring and tip electrodes and contact force (CF) using inductive sensors with an electroanatomical mapping system. In vitro, 51µm thermocouples were placed in explanted cardiac ventricular swine tissue to measure the temperature profile during RF delivery. The correlation between the LI drop during RF and intra-lesion temperature was assessed. A total of 44 lesions were created. Intra-lesion temperature was measured using 3 51µm thermocouples placed 0mm, 2mm, and 4mm from the surface of the tissue. The probes were placed in-line, 0.5-1mm lateral to the catheter tip. Lesions were created at a constant force of 15 ± 3g at standard powers of 25W and 30W and high power of 50W for durations of 10s and 30s. LI drop correlated strongly with lesion depth (R = 0.81) while force time integral (FTI) did not correlate as strongly (R = 0.58). As seen in Figure 1A (temperature traces inverted), a characteristic temperature increase was observed, with the greatest increase at the probes located in the lesion core (2mm). Lower temperatures were observed in the probes exposed to irrigation flow/ bloodpool (0mm). Notably, the LI drop (33Ω) demonstrated a similar slope to the 2mm temperature probe recordings (maximum 78°C). There was a strong linear relationship between maximum intra-lesion temperature and LI drop (R = 0.74) (Figure 1B), while there was a very weak relationship between temperature and FTI (R = 0.36). There was a strong relationship between LI drop and maximum temperature in the first 5s across all powers (R = 0.81). At 50W, both LI drop (22 ± 5Ω) and maximum temperature (66 ± 9°C) were greater than standard power. For 30W, LI drop was 14 ± 6Ω and maximum temperature was 52 ± 7°C in the first 5 seconds. In this study, LI drop was highly correlated to intra-lesion temperature at standard and high power, demonstrating the sensitivity of the metric to volumetric heating under the tissue surface. A LI drop greater than 20Ω results in a tissue temperature >50°C, and a 30Ω LI drop likely results in a transmural temperature profile in 2mm tissue. The correlation of LI to the core lesion temperature provides a powerful, biophysical measure of tissue heating during RF ablation. Abstract Figure 1

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In vivo biophysical characterization of very high power, short duration, temperature‐controlled lesions

Pacing and Clinical Electrophysiology ◽

10.1111/pace.14358 ◽

2021 ◽

Vol 44 (10) ◽

pp. 1717-1723

Author(s):

Giuseppe Stabile ◽

Vincenzo Schillaci ◽

Teresa Strisciuglio ◽

Alberto Arestia ◽

Alessia Agresta ◽

...

Keyword(s):

Short Duration ◽

High Power ◽

Biophysical Characterization ◽

Temperature Controlled ◽

Very High

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Temperature controlled high power short duration ablation with 90 watts for 4 seconds: Outcome, safety, biophysical characteristics and cranial MRI findings in patients undergoing pulmonary vein isolation

10.22541/au.162308145.53421927/v1 ◽

2021 ◽

Author(s):

Marc Kottmaier ◽

Leonie Förschner ◽

Nada Harfoush ◽

Felix Bourier ◽

Sarah Mayr ◽

...

Keyword(s):

Pulmonary Vein ◽

Short Duration ◽

Pulmonary Vein Isolation ◽

High Power ◽

Tissue Temperature ◽

Neurological Deficits ◽

Cerebral Lesions ◽

Number Of Patients ◽

Cerebral Mri ◽

Temperature Controlled

Background High power short duration (HPSD) radiofrequency-ablation (RFA) is highly efficient and safe while reducing procedure and RF time in pulmonary vein isolation (PVI). The QDot-catheter is a novel contact-force ablation catheter that allows automated flow and power adjustments depending on the local tissue temperature to maintain a target temperature during 90watts/4seconds lesions. We analysed intraprocedural data and periprocedural safety using the QDot-catheter in patients undergoing PVI for paroxysmal atrial fibrillation (PAF). Methods We included n=48 patients undergoing PVI with the QDot-catheter with a temperature controlled HPSD ablation mode with 90watts/4seconds (TC-HPSD). If focal reconnection occurred besides repeat ablation the ablation mode was changed to 50watts/15seconds (QMode). N=23 patients underwent cerebral MRI to detect silent cerebral lesions. Results Mean RF-time was 8.1+/-2.8min, procedure-duration was 84.5+/-30min. The overall maximal measured catheter-tip temperature was 52.0°C +/- 4.6°C, mean overall applied current was 871mA +/-44mA and over all applied energy was 316J +/-47J. The mean local impedance-drop was 12.1 +/- 2.4 Ohms. During Adenosine challenge n=14 (29%) patients showed dormant conduction. A total of n=24 steam pops were detected in n=18 patients (39.1%), while no pericardial tamponade occurred. No periprocedural thromboembolic complications occurred, while n=4 patients (17.4%) showed silent cerebral lesion. Conclusion TC-HPSD ablation with 90watts/4seconds using the QDot-catheter led to a reduction of procedure and RF time, while no major complications occurred. Despite optimized temperature control and power adjustment steam pops occurred in a rather high number of patients, while none of them lead to tamponade or to clinical or neurological deficits.

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Systematic Characterization of High-Power Short-Duration Ablation: Insight From an Advanced Virtual Model

Frontiers in Medical Technology ◽

10.3389/fmedt.2021.747609 ◽

2021 ◽

Vol 3 ◽

Author(s):

Argyrios Petras ◽

Zoraida Moreno Weidmann ◽

Massimiliano Leoni ◽

Luca Gerardo-Giorda ◽

Jose M. Guerra

Keyword(s):

Short Duration ◽

High Power ◽

Safety Margin ◽

Tissue Temperature ◽

Clinical Approach ◽

Virtual Model ◽

Saline Irrigation ◽

Blood Temperature ◽

Catheter Tip

Background: High-power short-duration (HPSD) recently emerged as a new approach to radiofrequency (RF) catheter ablation. However, basic and clinical data supporting its effectiveness and safety is still scarce.Objective: We aim to characterize HPSD with an advanced virtual model, able to assess lesion dimensions and complications in multiple conditions and compare it to standard protocols.Methods: We evaluate, on both atrium and ventricle, three HPSD protocols (70 W/8 s, 80 W/6 s, and 90 W/4 s) through a realistic 3D computational model of power-controlled RF ablation, varying catheter tip design (spherical/cylindrical), contact force (CF), blood flow, and saline irrigation. Lesions are defined by the 50°C isotherm contour. Ablations are deemed safe or complicated by pop (tissue temperature >97°C) or charring (blood temperature >80°C). We compared HPSD with standards protocols (30–40 W/30 s). We analyzed the effect of a second HPSD application.Results: We simulated 432 applications. Most (79%) associated a complication, especially in the atrium. The three HPSD protocols performed similarly in the atrium, while 90 W/4 s appeared the safest in the ventricle. Low irrigation rate led frequently to charring (72%). High-power short-duration lesions were 40–60% shallower and smaller in volume compared to standards, although featuring similar width. A second HPSD application increased lesions to a size comparable to standards.Conclusion: High-power short-duration lesions are smaller in volume and more superficial than standards but comparable in width, which can be advantageous in the atrium. A second application can produce lesions similar to standards in a shorter time. Despite its narrow safety margin, HPSD seems a valuable new clinical approach.

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