Ablation Lesions Research Articles

Development of a murine laser interstitial thermotherapy system.

The objective of this study was to develop a murine system for the delivery of laser interstitial thermotherapy (LITT) with probe-based thermometry as a model for human glioblastoma treatment to investigate thermal diffusion in heterogeneous brain tissue. First, the tissue heating properties were characterized using a diode-pumped solid-state near-infrared laser in a homogeneous tissue model. The laser was adapted for use with a repurposed stereotactic surgery frame utilizing a micro laser probe and Hamilton syringe. The authors designed and manufactured a stereotactic frame attachment to work as a temperature probe stabilizer. Application of this novel design was used as a precise method for real-time thermometry at known distances from the thermal ablative center mass during murine LITT studies. Temperature measurements were achieved during LITT that verified the direct thermometry capability of the system without the need for MR-based thermal monitoring. Application of multiple stereotactic design iterations led to an accurately reproducible surgical laser ablation procedure. Histological staining confirmed precise thermal ablation and controllable lesion size based on time and temperature control. Treatment of a syngeneic intracranial glioma model highly resistant to conventional therapy resulted in a modest survival benefit. The authors have successfully developed a murine model system of LITT with direct in situ thermometry for investigation into the effects of thermal ablation and combinatorial treatments in murine brain tumor models.

Long-term prognosis in patients undergoing atrial fibrillation ablation

Abstract Aims The aim of the analysis was to assess the risk of atrial fibrillation (AF) recurrence in the long-term observation of contemporary patients undergoing pulmonary vein isolation (PVI), who did not have recurrence during the first year after catheter ablation. Methods Retrospective analysis has been performed. Inclusion criteria: (1) the patients undergoing their first PVI in years 2017–2022, (2) the electroanatomical system, contact force catheters and lesion indexes (Ablation Index or Lesion Size Index) were used, (3) no recurrences were observed during the first 12 months of follow-up, and (4) follow-up longer than 12 months was available. Demographic, clinical and echocardiographic data were collected. Follow-up was based on ambulatory visits with ECG/holter monitoring or implanted device interrogation, when available. Results A total of 247 patients were included. The median follow-up was 22 months (interquartile range, 16–31 months). After 24 months, ablation efficacy was 84%, and after 36 months, it was 72%. In the univariate Cox regression analysis, age, previous electrical cardioversion, glomerular filtration rate (eGFR) and the presence of coronary artery disease were linked to AF-free survival. Interestingly, nonparoxysmal AF, left atrial (LA) dimension, heart failure, hypertension or diabetes were not linked to the risk of long-term recurrences. In multivariate Cox regression analysis, presence of coronary artery disease and previous electrical cardioversion were independently linked to the risk of long-term recurrence. In 127 (51.4%) patients, information about the presence of low voltage areas (LVA) was available, and in 21 (16.5%) patients in this group, the presence of LVA was found. Survival of patients with LVA was strikingly worse than that of those without (Figure 1), log-rank test p <0.0001. Conclusions Patients who had no recurrences within one year after PVI, still have substantial risk of recurrence in the next 2 years. That concerns specially the patients who had LVA in the electroanatomical mapping.

Prevalance of incessant form of atrial fibrillation by superior vena cava (svc) firing:simplified svc and sinus node mapping(sss map) to avoid sinus node injury

Abstract Background The superior vena cava (SVC) is known as a major source of atrial fibrillation(AF), non-pulmonary vein AF foci (NPVAF). In some cases, an incessant form of AF (iAF) by SVC firing prevents obtaining the sinus node location, and anatomical SVC isolation has a risk of sinus node injury (SNI). Objective This study was aimed to explore the frequency of iAF by SVC firing and the efficacy of the simplified mapping strategy to avoid SNI. Methods Consecutive AF ablation procedures in the 3 centers were retrospectively investigated including the NPVAF prevalence. Simplified SVC/SN mapping (SSS-map: Obtaining the top-end of the SVC potential and >4points with 5-10mm spacing in the upper lateral side of the right atria (RA) for roughly locating the earliest activation site in sinus rhythm) was performed before PV isolation in the last 138 patients. In case of the initial rhythm at the procedure was atrial fibrillation, cardioversion was performed for obtaining the SSS-map. In the cases in which the high-density mapping catheters were available, the high-density activation maps of the RA in sinus rhythm were obtained to investigate the dislocation of the earliest activation site of the SSS map from the SN location. When SVC isolation was required due to iAF, SVC isolation line was designed based on the location of the top-end of the SVC potential during AF and ablative linear lesions were created to keep the distance of 5-10 mm above the second earliest activation site. Results A total of 1160 procedures in 1089 patients (male: 736[63.4%], age: 69.9, paroxysmal AF: 544[49.9%], first session: 997[85.9%]) was investigated. Prevalence of NPVAF was revealed in 160 of the all procedures (13.7%) (the SVC: 64, the posterior wall of the left atria: 24, the coronary sinus: 19, and others: 53). 16 of 160 NPVAFs (10.0%) developed to iAF by SVC firing. The SSS-map was successfully obtained in all of the last 138 patients (Initial rhythm at the procedure: AF 43.7%, Mapping time: 1.3±0.6 min, number of obtained points: 8.4±1.3). In 21 patients in which the high-density RA map was obtained, the SN dislocation distance was 5.1±2.2mm between the SSS map and the high-density RA map. Five of 138 developed to iAF by SVC firing, and SVC isolation based on the SSS-map was successfully achieved without SNI in the cases. Conclusion This study indicated iAF driven by SVC firing after PV isolation occurred in certain number of patients. The SSS-map before PV isolation was practical and showed the potential to be the mapping strategy avoid the SN injury in such cases.

Detecting epicardial connection through intercaval bundle using intra-atrial activation sequence during right pulmonary vein pacing

Abstract Background An epicardial connection (EC) through the intercaval bundle (EC-ICB) between the right pulmonary vein (RPV) and the right atrium (RA) is one of the reasons for the need of carina ablation for PV isolation. Purpose We evaluated the intra-atrial activation sequence during RPV pacing after failure of ipsilateral RPV isolation and sought to identify specific conduction patterns in the presence of the EC-ICB. Methods This study included 223 consecutive patients undergoing initial catheter ablation of atrial fibrillation. If the RPV was not isolated by circumferential ablation or reconnected during the waiting period, an exit map during mid RPV carina pacing was created. If the earliest site of the exit map was the RA, the patient was classified into the EC-ICB group. During the exit map, intra-atrial activation sequence and RPV-HRA time were evaluated. Results First-pass isolation of the RPV was not obtained in 36 patients (16.1%), and 22 patients (9.9%) showing reconnection. Among them, 12 patients were classified into the EC-ICB group and 28 patients into the Non-EC-ICB group after excluding multiple ablation lesion sets or incomplete mapping. Intra-atrial activation sequence showed different patterns between the two groups. RPV-HRA time was significantly shorter in the EC-ICB group compared to the Non-EC-ICB group (69.2 ± 15.2 ms v.s. 148.6 ± 51.2 ms. P<0.001), and RPV-HRA time<89.0ms was highly predictive for existence of the EC-ICB (sensitivity 91.7 %, specificity 89.3 %). Conclusions The EC-ICB can be effectively detected by intra-atrial sequencing during RPV pacing and RPV-HRA time<89.0ms was highly predictive.

"Honey pot"-like lesion formation: impact of catheter contact angle on lesion formation by novel temperature controlled ablation catheter in a porcine experimental model

Abstract Background The DiamondTemp(DT) catheter enables precise temperature-controlled ablation. However, the effects of the DT catheter's contact angle on lesion formation are poorly understood. Purpose This study evaluated lesion formation using the DT catheter at different angles in a porcine experimental model. Methods We used freshly sacrificed porcine hearts, and radiofrequency catheter ablation with DT was performed at 50 watts for 15 seconds at an upper-temperature setting of 60°C. The contact force (5, 10, and 30 grams) and catheter contact angles (30°, 45°, and 90°) were changed in each set (n = 13 each). The surface width (SW), maximum lesion width (MW), lesion depth (LD), surface area (SA), and distance from the distal edge to the widest area (DW) were evaluated. In addition, the generator impedance drop during radiofrequency application was analyzed. Results Figure 1 shows the summarized data in this study. SW and MW were longer at 30° than at 90° (SW 5 g: 6.34 ± 0.91 vs. 5.07 ± 0.87 mm; SW 10 g: 7.46 ± 0.55. vs. 5.60 ± 0.84 mm; SW 30 g: 7.42 ± 0.74. vs. 6.14 ± 0.77 mm; MW 10 g: 8.81 ± 0.55. vs. 7.89 ± 0.84 mm; MW 30 g: 9.24 ± 0.67. vs. 8.03 ± 1.04 mm, p <0.05, respectively). There were no significant differences in LD by catheter angle except at 30 g. SA was larger at 30° than at 90° (SA 5 g: 30.03 ± 0.91. vs. 23.61 ± 0.87; SA 10 g: 29.24 ± 0.55. vs. 21.27 ± 0.84; SA 30 g: 35.86 ± 0.74. vs. 31.74 ± 0.77, p <0.05, respectively). Besides, DW was longer at 30° than at 90° (DW 5 g: 4.28 ± 1.17. vs. 2.50 ± 0.32 mm; DW 10 g: 4.94 ± 0.52. vs. 2.47 ± 0.38 mm; DW 30 g: 5.34 ± 0.26. vs. 2.96 ± 0.40 mm, p <0.05, respectively). There were no significant differences in the impedance drop according to the catheter angle. Conclusion With the DT catheters, the lesion width increased at a shallower contact angle, whereas the LD did not. SA also increased at a shallower contact angle. The DT catheter created a large ablation lesion on the proximal side of the catheter, which looked like a "honey pot." (Figure 2)summarized dataImage of honey pot-like lesion formation

An in-silico comparison of anatomical and substrate based AF ablation using electro and optical flow mapping

Abstract Background The pursuit of improved outcomes for persistent AF may necessitate the utilization of innovative technologies and ablation methods. We hypothesize that combining electrophysiologic phase and optical flow mapping could offer a novel approach to identify ablation sites in persistent AF while minimizing ablation area, thereby enhancing the effectiveness of substrate-based ablation compared to a purely empiric strategy. Objective To compare the efficacy of a novel electro-optic flow-based ablation strategy (EOF) with empiric ablation for persistent AF patients using a virtual cohort of bi-atrial models. Methods An exploratory cohort (n=20) from a CT-derived bi-atrial in silico population was utilized to simulate AF. A pipeline was developed to assess ablation targets based on simulated AF and to automatically connect targets to closest inert boundaries. As part of target assessment, phase singularities (PS) and Horn-Schunck average optical flow maps were computed. An intersection of information assessed through PS and curl of average optical flow was utilized to generate EOF maps. 5 x strategies comprising purely anatomical, PS based and EOF guided ablations were simulated (1. PVI; 2. PVI+mitral/roof lines; 3. PVI+mitral/box line; 4. PS+anatomical; 5. EOF+anatomical). Ablation efficacy was determined by first examining change of rhythm via ablation and second by calculating the amount of tissue area ablated. Results Ablating PVI alone (Method 1) did not result in AF termination in any case. Ablating PVI with mitral or roof lines (Method 2) resulted in moderate outcomes (6 AF term. / 3 conv. to AT) whereas ablating PVI with mitral and box lines (Method 3) resulted in improved outcomes (9 AF term. / 4 conv. to AT). Compared to purely anatomical approaches, ablating PS or EOF targets and combining them with roof, mitral lines (Method 4 and Method 5 respectively) saw marked improvement (16 AF term. / 2 conv. to AT). Mapping based on EOF (Method 5) resulted in smaller ablation targets compared to a PS guided strategy (Method 4) with the same outcome. Conclusion AF termination to ablated tissue area ratio was higher for EOF based ablation targets compared to PS based or empiric ablations. Algorithmic generation of ablation lesion masks based on predicted targets can provide novel insights into ablation outcomes. Combining EOF targets with empiric lesions represents a potential ablation strategy of individualized substrate modification for persistent AF.Study Pipeline

Biomarkers in early and late period after radiofrequency and pulsed field catheter ablation of atrial fibrillation

Abstract Introduction Biomarkers are routinely used parameters for disease diagnosis, treatment control and risk stratification. In connection with atrial fibrillation (AF), the importance of GDF-15 (growth differentiation factor 15), NT-proBNP (N-terminal fragment brain natriuretic factor) and hs-TnT (high sensitivity cardiac troponin T) is discussed. Catheter ablation is an established treatment method in selected population with AF. However, biomarker response to radiofrequency catheter ablation (RFCA) and pulsed field ablation (PFA) of AF has not been precisely described. Purpose Purpose of the study was to describe early and late dynamics of GDF-15, hs-TnT and NT-proBNP in different ablation technologies. Methods We prospectively enrolled 48 patients (median (IQR) age 62 (55; 70) years, 30 males) undergoing RFCA, which we compared with 30 patients (median (IQR) age 64 (56; 71) years, 18 males) undergoing PFA. All patients underwent 6 sequential blood takes: before ablation (baseline), right after ablation (0h), 24 and 48 hours after procedure (24h and 48h), 90 and 180 days after procedure. Levels of GDF-15, hs-TnT and NT-proBNP were analyzed. Results Out of all patients, 19 (40 %) and 20 (67 %) patients had paroxysmal AF in RFCA and PFA group, respectively. Additional ablation lesions over pulmonary vein isolation were done in 26 (54 %) patients in RFCA group and 11 (43 %) patients in PFA group. Median procedural time was significantly longer in RFCA than in PFA group (155 (130; 190) vs. 80 (70; 90) min; p < 0.01). Early dynamics of GDF-15 and cardiac hs-TnT are visualised in Figure 1 and 2. GDF-15 level peak was registered 48 hours after ablation with median (IQR) 1183 (824; 1988) ng/l. Compared to baseline, GDF-15 values sustained elevated up to 90 days after ablation in both groups and decreased to baseline levels after 180 days. No significant differences were found in GDF-15 levels between patients treated with RFCA and PFA. Maximal values of hs-TnT were significantly higher in PFA group than in RFCA group (1001±589 vs. 458±202 ng/l; p < 0.001). We have recognised decrease of NT-proBNP between baseline and 90 days after procedure in both groups: 338 (112; 613) vs. 209 (101; 545) ng/l; p < 0.05. Conclusion Eventhough GDF-15 is considered as a nonspecific biomarker reflecting general condition of patient, the levels are significantly affected by catheter ablation of AF for several months irrespective to ablation technology. PFA is associated with advanced elevation of hs-TnT.Dynamics of GDF-15 (median; IQR)Dynamics of hs-TnT (median; IQR)

National Trends in Laryngeal Laser Surgery: Comparison of Operative Versus Office-Based Procedures.

To analyze national trends in the prevalence of office-based laryngeal ablative procedures and compare those with traditional operative excisional procedures utilizing direct laryngoscopy. For years 2013-2022, the US Medicare Part B claims database was searched for Current Procedural Terminology (CPT) codes 31572 (flexible laryngoscopy with laser ablation of lesion), 31540 (operative direct laryngoscopy with excision of lesion), 31541 (operative direct microlaryngoscopy with excision of lesion), and 31545 (operative direct microlaryngoscopy with excision of lesion and local tissue flap reconstruction). For each CPT code, the total number of charges billed to the Medicare database in each calendar year was recorded and annual trends were analyzed. Biopsy procedures were not included. The annual number of office-based laser procedures (CPT 31572) remained relatively constant since the CPT code was introduced in 2017 (range: 18887-25241 procedures annually, trendline slope = +16, R2:0.02). Office-based laser procedures comprised a small portion of total laryngeal excisional procedures (range: 8.4%-12.1%). The total number of operative laryngeal excisions, billed by CPT 31540 and 31541, declined over the studied time frame (Trendline slope = -132, R2:0.93; Trendline slope = -950, R2: 0.93 respectively). Office-based laser procedures comprise a small fraction of procedures to remove laryngeal lesions. The number of office-based laser procedures has been relatively stable over the last 5 years. This finding contrasts with the prevailing health care trend toward office-based procedures. Further research is needed to understand the decrease in operative laryngeal lesion excision procedures observed over the last 10 years. 4 Laryngoscope, 2024.

Injectable Magnetic Hydrogel Incorporated with Anti-Inflammatory Peptide for Efficient Magnetothermal Treatment of Endometriosis.

Endometriosis is a prevalent gynecological condition characterized by chronic pelvic pain, dysmenorrhea, and infertility, affecting ≈176 million women of reproductive age worldwide. Current treatments, including pharmacological and surgical interventions, are often associated with significant side effects and high recurrence rates. Consequently, there is an urgent need for innovative and safer therapeutic approaches. In this study, an injectable magnetic hydrogel nanosystem is developed designed for the dual-purpose magnetothermal and anti-inflammatory treatment of endometriosis. This hydrogel incorporates Fe3O4 nanoparticles alongside an anti-inflammatory peptide. Upon magnetic activation, the Fe3O4 nanoparticles induce a localized hyperthermic response, raising the temperature of endometriotic lesions to 63.3°C, effectively destroying endometriotic cells. Concurrently, the thermally responsive hydrogel facilitates the controlled release of the anti-inflammatory peptide, thus modulating the inflammatory milieu. The biocompatibility and complete in vivo degradability of the hydrogel further enhance its therapeutic potential. The in vivo studies demonstrated that this injectable magnetic hydrogel system achieved a 90% reduction in the volume of endometriotic lesions and significantly decreased inflammatory markers, offering a promising non-invasive treatment modality for endometriosis. By integrating precise lesion ablation with the modulation of the inflammatory microenvironment, this system represents a novel approach to the clinical management of endometriosis.

Local calcium chloride infusion after pulsed field ablation enhances acute efficacy of cardiac electroporation.

Pulsed field ablation (PFA) has emerged as an innovative therapy for cardiac arrhythmias. Drawing parallels with PFA's application in solid tumors, calcium chloride (CaCl2) as an adjuvant therapy, known as calcium electroporation, may amplify PFA's apoptotic effects. We propose that PFA in the atrium could enhance calcium uptake through PFA-created pores, thereby increasing ablation efficacy even at reduced power levels by exploiting PFA's permeabilization effects. We conducted in vivo ablations on the atria of seven pigs using low PFA power (250 V, 20 μs for 50 pulses at 200 ms intervals). Post-PFA, we randomly administered an infusion of either 200 mg/2 ml CaCl2 (calcium group) or saline (control) directly to the ablation site via the catheter tip. We evaluated reduction in electrogram voltage amplitude, electrocardiography (ECG) parameters, ablation lesion parameters, and histology after PFA. Nineteen lesions from control and calcium groups were examined. Control lesions showed no voltage decrease post-PFA, whereas calcium-treated lesions exhibited a significant voltage reduction. Gross pathology indicated marked differences in maximum lesion surface diameter, depth, and volume between the lesion groups. Histologically, calcium group lesions were characterized by a more severe acute PFA response with contraction band necrosis, myocytolysis and nuclear pyknosis in adjacent myocardium, in addition to microhemorrhages. Infusing calcium chloride locally after PFA markedly improves the immediate efficacy of electroporation in porcine atria. This study suggests that calcium electroporation could bolster PFA outcomes without higher energy levels, potentially diminishing associated risks. These preliminary findings warrant further research into the long-term efficacy and potential clinical application of calcium electroporation in PFA.

In vitro characterization of radiofrequency ablation lesions in equine and swine myocardial tissue

Radiofrequency ablation is a promising technique for arrhythmia treatment in horses. Due to the thicker myocardial wall and higher blood flow in horses, it is unknown if conventional radiofrequency settings used in human medicine can be extrapolated to horses. The study aim is to describe the effect of ablation settings on lesion dimensions in equine myocardium. To study species dependent effects, results were compared to swine myocardium. Right ventricular and right and left atrial equine myocardium and right ventricular swine myocardium were suspended in a bath with circulating isotonic saline at 37 °C. The ablation catheter delivered radiofrequency energy at different-power-duration combinations with a contact force of 20 g. Lesion depth and width were measured and lesion volume was calculated. Higher power or longer duration of radiofrequency energy delivery increased lesion size significantly in the equine atrial myocardium and in equine and swine ventricular myocardium (P < 0.001). Mean lesion depth in equine atrial myocardium ranged from 2.9 to 5.5 mm with a diameter ranging from 6.9 to 10.1 mm. Lesion diameter was significantly larger in equine tissue compared to swine tissue (P = 0.020). Obtained data in combination with estimated wall thickness can improve lesion transmurality which might reduce arrhythmia recurrence. Optimal ablation settings may differ between species.

Lesion characteristics using high-frequency low-tidal volume ventilation versus standard ventilation during ablation of paroxysmal atrial fibrillation.

High-frequency low-tidal-volume (HFLTV) ventilation during radiofrequency catheter ablation (RFCA) for paroxysmal atrial fibrillation (PAF) has been shown to be superior to standard ventilation (SV) in terms of procedural efficiency, acute and long-term clinical outcomes. Our study aimed to compare ablation lesions characteristics utilizing HFLTV ventilation versus SV during RFCA of PAF. A retrospective analysis was conducted on patients who underwent pulmonary vein isolation (PVI) for PAF between August 2022 and March 2023, using high-power short-duration ablation. Thirty-five patients underwent RFCA with HFLTV ventilation and were matched with another cohort of 35 patients who underwent RFCA with SV. Parameters including ablation duration, contact force (CF), impedance drop, and ablation index were extracted from the CARTONET database for each ablation lesion. A total of 70 patients were included (HFLTV = 35/2484 lesions, SV = 35/2830 lesions) in the analysis. There were no differences in baseline characteristics between the groups. While targeting the same ablation index, the HFLTV ventilation group demonstrated shorter average ablation duration per lesion (12.3 ± 5.0 vs. 15.4 ± 8.4 s, p < .001), higher average CF (17.0 ± 8.5 vs. 10.5 ± 4.6 g, p < .001), and greater impedance reduction (9.5 ± 4.6 vs. 7.7 ± 4.1 ohms, p < .001). HFLTV ventilation group also demonstrated shorter total procedural time (61.3 ± 25.5 vs. 90.8 ± 22.8 min, p < .001), ablation time (40.5 ± 18.6 vs. 65.8 ± 22.5 min, p < .001), and RF time (15.3 ± 4.8 vs. 22.9 ± 9.7 min, p < .001). HFLTV ventilation during PVI for PAF was associated with improved ablation lesion parameters and procedural efficiency compared to SV.

Body mass index as a determinant of scar formation post-AF ablation: Insights from DECAAF II.

Obesity is implicated in adverse atrial remodeling and worse outcomes in patients with atrial fibrillation. The objective of this study is to assess the effect of body mass index (BMI) on ablation-induced scar formation on late gadolinium enhancement cardiac magnetic resonance imaging (LGE-CMR). We conducted an analysis of DECAAF II participants who underwent LGE-CMR scans to measure scar formation 3 months after catheter ablation. Ablation parameters and lesion delivery were not dependent on BMI. The effect of BMI on ablation success was explored. Our analyses included 811 patients. Comorbidities were more prevalent in obese patients. Baseline left atrial volume was higher in obese individuals, 118, 126, 135, 140, and 143 mm3 for normal weight, overweight, obese grade 1, 2, and 3, respectively (p < .001). BMI was associated with scar formation (R = -0.135, p < .001), with patients with Class 3 obesity having the lowest percentage of ablation-induced scar, 11.1%, 10.3%, 9.5%, 8.8%, 6.8% by ascending BMI group. There was an inverse correlation between BMI and the amount of fibrosis covered by ablation scar, 24%, 23%, 21%, and 18% by ascending BMI group (p = .001). For the fibrosis-guided ablation group, BMI was associated with residual fibrosis (R = 0.056, p = .005). Obese patients have lower ablation scar formation, covered fibrosis, and more residual fibrosis postablation compared to nonobese patients, regardless of ablation parameters including impedance drop.

Outcomes and Complications of Image-Guided Percutaneous Tumour Ablation for Hepatocellular Carcinoma at the Irish National Liver Transplant Centre.

Background: Image-guided tumour ablation is a minimally invasive treatment for early stage hepatocellular carcinoma (HCC). Our study reviews the complications and long term outcomes in patients treated at a tertiary referral centre. Methods: Retrospective study. All patients with HCC who underwent microwave ablation (MWA) or radiofrequency ablation (RFA) from 1st January 2014 to 31st December 2022 were identified. Treatment response of target lesion, complications, and survival were recorded. Results: One hundred seventy ablations were performed in 118 patients; 70% MWA, 30% RFA. Median radiological follow-up 21 months (range 3-107). Follow-up imaging was reported using LI-RADS and mRECIST. At first follow-up imaging, 94 patients had complete response (primary efficacy rate 80.3%) while 19.7% (n = 23) had residual disease. Fifteen of these had repeat ablation; 10 had complete response (secondary efficacy rate 85.6%). By end of study duration, 70.5% (n = 79) achieved sustained local complete response from single ablation without documented recurrence. 14.3% (n = 16) required more than one ablation of target lesion. Overall, 84.8% (n = 95) demonstrated long term local complete response to ablation. Complication occurred in 5.9% (n = 10); 40.0% Grade I, 40.0% Grade II, 10.0% Grade III, 10.0% Grade IV as per the CIRSE Classification. 1-, 3-, and 5-year overall survival (OS) rate was 97%, 68%, and 61% respectively. Mean OS was 5.3 years (median 4.7). No difference in OS (P = .7) or local progression free survival (P = .5) between patients treated with MWA versus RFA. Conclusion: This study demonstrates excellent long-term response to TA, with acceptable complication profile. No difference in survival between RFA versus MWA.

Shear Wave Elastography in Evaluating the Efficacy of Liver Microwave Ablation: An Experimental Study

Background: The effect of microwave ablation on small hepatocellular carcinoma is not significantly different from that of surgical resection. Accurate assessment of the ablation effect is crucial for ensuring the safety and effectiveness of hyperthermia. Objectives: This study aimed to explore the feasibility and accuracy of supersonic shear wave elastography (SWE) in quantitatively evaluating the microwave ablation margin of the liver. Materials and Methods: Three surgeons were each randomly assigned 4 Wuzhishan miniature pigs (WZSPs) to perform 12 ablation procedures at an ablation power of 40 W. Based on the ablation time, the lesions were divided into 15, 30, and 60-second groups. Immediately after ablation, SWE and modulus measurements were performed 5 times for each ablation lesion. The SWE data were expressed as mean ± standard deviation. Within-group and between-group comparisons were made using repeated measures analysis of variance. Results: A total of 144 effective ablations and 131 effective pathological results were obtained. Within the same ablation time, the elastic modulus increased in the surrounding normal tissue, ablation margin, and ablation center regions in a stepwise manner (P &lt; 0.01). However, in the ablation center region, the elastic modulus decreased in a stepwise manner with the shortening of ablation time [60 s (97.16 ± 14.58 kPa) &gt; 30 s (77.84 ± 9.64 kPa) &gt; 15 s (38.92 ± 3.12 kPa)], with statistically significant differences (F = 2,131.832, P &lt; 0.01). The elastic modulus of the ablation margin region at different ablation times remained between 22.68 - 23.56 kPa. Conclusion: The elastic modulus range in the ablation margin region after microwave ablation is relatively fixed. Shear wave elastography aids in the quantitative evaluation of the ablation margin region of the liver and has high practical value in monitoring and evaluating ultrasound ablation.

Detailed analysis of electrogram peak frequency to guide ventricular tachycardia substrate mapping.

Differentiating near-field (NF) and far-field (FF) electrograms (EGMs) is crucial in identifying critical arrhythmogenic substrate during ventricular tachycardia (VT) ablation. A novel algorithm annotates NF-fractionated signals enabling EGM peak frequency (PF) determination using wavelet transformation. This study evaluated the algorithms' effectiveness in identifying critical components of the VT circuit during substrate mapping. A multicentre, international cohort undergoing VT ablation was investigated. VT activation maps were used to demarcate the isthmus zone (IZ). Offline analysis was performed to evaluate the diagnostic performance of low-voltage area (LVA) PF substrate mapping. A total of 30 patients encompassing 198 935 EGMs were included. The IZ PF was significantly higher in sinus rhythm (SR) compared to right ventricular paced (RVp) substrate maps (234 Hz (195-294) vs. 197 Hz (166-220); P = 0.010). Compared to LVA PF, the IZ PF was significantly higher in both SR and RVp substrate maps (area under curve, AUC: 0.74 and 0.70, respectively). The LVA PF threshold of ≥200 Hz was optimal in SR maps (sensitivity 69%; specificity 64%) and RVp maps (sensitivity 60%; specificity 64%) in identifying the VT isthmus. In amiodarone-treated patients (n = 20), the SR substrate map IZ PF was significantly lower (222 Hz (186-257) vs. 303 Hz (244-375), P = 0.009) compared to amiodarone-naïve patients (n = 10). The ≥200 Hz LVA PF threshold resulted in an 80% freedom from VT with a trend towards reduced ablation lesions and radiofrequency times. LVA PF substrate mapping identifies critical components of the VT circuit with an optimal threshold of ≥200 Hz. Isthmus PF is influenced by chronic amiodarone therapy with lower values observed during RV pacing.

Additional Lesion Sets in Ablation of Outflow Tract Premature Ventricular Contractions: A Randomized Clinical Trial.

Recurrence remains a challenge after ablation of outflow tract premature ventricular contractions (OT-PVCs). Although adding additional lesions next to the index effective ablation site is sometimes performed to reinforce the ablation, it remains uncertain whether this approach is effective. To test the hypothesis that additional ablation lesions would reduce the recurrence rate compared with single-point ablation at the index effective site for the ablation of OT-PVCs. This study was a multicenter, prospective, randomized clinical trial. Patients receiving their first catheter ablation for OT-PVCs were enrolled from 18 hospitals in China between October 2021 and February 2023. Scheduled follow-up duration was 3 months after the procedure. After identifying the target point and eliminating the PVC by a single-point ablation, patients were randomized 1:1 into an additional ablation group or a control group. The primary end point of the study was freedom from PVC recurrence (≥80% reduction of PVC burden, which is the number of PVCs in 24 hours/total heartbeats in 24 hours × 100%) from baseline to 3 months postprocedure. Of 308 patients enrolled in the study, 286 (mean [SD] age, 49.2 [14.6] years; 173 female [60.5%]) were randomized to the additional ablation or the control group. The additional ablation group had a mean (SD) of 6.3 (1.1) radiofrequency applications, whereas the control group (single-point ablation group) had a mean (SD) of 1 (0) radiofrequency application. After a median (IQR) follow-up of 3.2 (0) months, the rate of freedom from PVCs was significantly higher in the additional ablation group (139 of 142 [97.9%]) compared with the control group (115 of 139 [82.7%]; P < .001). Patients in the additional ablation group also had a more substantial reduction in PVC burden than the control group (mean [SD] reduction, 23.0% [10.5%] vs 19.0% [10.4%]; P = .002). There were no severe periprocedural complications in either group. This randomized clinical trial showed a benefit of additional ablation in reducing the recurrence of OT-PVCs compared with the single-point ablation strategy, without increased complication risk. Additional ablations surrounding the index effective ablation point should be considered in OT-PVC ablation. Chinese Clinical Trials Registry Identifier: ChiCTR2200055340.

In vivo assessment of cardiac radiofrequency ablation in a large-animal model using photoacoustic-ultrasound imaging.

One of the fundamental unmet clinical needs within cardiac electrophysiology is intraoperative assessment of catheter ablation, which can lead to recurrent arrhythmias and subsequent complications if ineffective. This work demonstrates photoacoustic imaging (PAI) of radiofrequency ablation (RFA) lesions in an in vivo swine model (n=3). Spectral unmixing of PAI data provides local myocardial characterization (e.g., oxygen saturation & tissue ablation) by overlaying unmixed PAI images with B-mode ultrasound imaging (PAI/US), with the latter providing anatomical context. Based on stained gross pathology, areas of central tissue necrosis coincided with increases in unmixed ablated regions of the myocardium. An average contrast-to-noise ratio of 2.8±0.2 confirmed lesion detectability, while the lesion dimensions quantified from PAI and pathology did not present significant differences. In vivo PAI of RFA lesions to determine ablation characteristics could lead to a paradigm shift in catheter ablation assessment and improve clinical outcomes.

Evaluation of a Three-Dimensional Printed Interventional Simulator for Cardiac Ablation Therapy Training

Cardiac ablation (CA) is an interventional electrophysiological procedure used to disrupt arrhythmic substrates in the myocardium by inducing localized scarring. Current CA training relies on the master–apprentice model. In different fields of medicine including CA, virtual and physical simulators have proven to enhance, and even outperform, conventional training modalities while providing a risk-free learning environment. Despite the benefits, high costs and operational difficulties limit the widespread use of interventional simulators. Our previous research introduced a low-cost CA simulator using a 3D-printed biatrial cardiac model, successfully recording ten ablation lesions on the phantom myocardium. In this work, we present and evaluate an enhanced version: compared to the previous version, the cardiac phantom’s electrical behavior and ablation settings were optimized to produce consistent lesions, while 3D-printed components improved the haptic and radiographic properties of the simulator. Seven cardiologists compared the experimental simulator’s performance to the leading commercial system from Heartroid in a 24-question survey on a 5-point Likert scale. The four following areas of fidelity were considered: catheter entry, anatomical correctness, radiographic appearance, and mapping and ablation. The experimental simulator significantly outperformed the commercial system (p &lt; 0.01), particularly in radiographic appearance (p &lt; 0.01). The results show the potential for the experimental simulator in routine CA training.

Novel systematic processing of cardiac magnetic resonance imaging identifies target regions associated with infarct-related ventricular tachycardia.

There is lack of agreement on late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) imaging processing for guiding ventricular tachycardia (VT) ablation. We aim at developing and validating a systematic processing approach on LGE-CMR images to identify VT corridors that contain critical VT isthmus sites. This is a translational study including 18 pigs with established myocardial infarction and inducible VT undergoing in vivo characterization of the anatomical and functional myocardial substrate associated with VT maintenance. Clinical validation was conducted in a multicentre series of 33 patients with ischaemic cardiomyopathy undergoing VT ablation. Three-dimensional LGE-CMR images were processed using systematic scanning of 15 signal intensity (SI) cut-off ranges to obtain surface visualization of all potential VT corridors. Analysis and comparisons of imaging and electrophysiological data were performed in individuals with full electrophysiological characterization of the isthmus sites of at least one VT morphology. In both the experimental pig model and patients undergoing VT ablation, all the electrophysiologically defined isthmus sites (n = 11 and n = 19, respectively) showed overlapping regions with CMR-based potential VT corridors. Such imaging-based VT corridors were less specific than electrophysiologically guided ablation lesions at critical isthmus sites. However, an optimized strategy using the 7 most relevant SI cut-off ranges among patients showed an increase in specificity compared to using 15 SI cut-off ranges (70 vs. 62%, respectively), without diminishing the capability to detect VT isthmus sites (sensitivity 100%). Systematic imaging processing of LGE-CMR sequences using several SI cut-off ranges may improve and standardize procedure planning to identify VT isthmus sites.