RESUMEN
BACKGROUND: During pulsed field ablation (PFA), relationships between ablation parameters (contact force [CF], number of burst pulses, impedance decrease, and electrode temperature) and lesion size in beating hearts have not been well validated. METHODS: A 7.5F-catheter with a 3.5-mm ablation electrode and CF sensor (ThermoCool SmartTouch SF-Dual-Energy, Biosense Webster, Inc, Irwindale, CA) was connected to a PFA system (TRUPULSE2, Biosense Webster, Inc). In 11 closed-chest swine, biphasic PFA current was delivered between the ablation electrode and the skin patch at 219 sites in left ventricle and right ventricle using 12, 18, and 24 burst pulses with 4 different levels of CF: (1) low (n=57; CF, 4-15g; median, 10g); (2) moderate (n=60; CF, 16-30g; median, 22.5g); (3) high (n=68; CF, 32-65g; median, 40g); and (4) no electrode contact (n=34), 2 mm away from the endocardium. Swine were euthanized 2 hours after ablation, and lesion size was measured using triphenyl tetrazolium chloride staining. RESULTS: All PFA lesions with electrode-myocardium contact were well demarcated with triphenyl tetrazolium chloride staining, demonstrating (1) pale central zone (contraction band necrosis with minimal coagulation necrosis), (2) dark brown zone (contraction band necrosis with hemorrhage), and (3) hyperstained red zone by triphenyl tetrazolium chloride (unaffected normal myocardium with preserved mitochondrial activity, consistent with reversible zone). Lesion depth increased significantly with increasing CF and the number of PFA burst pulses. An exponential/logarithmic formula combined with CF and the number of PFA burst pulses correlated lesion depth with high accuracy: R=0.809, P<0.0001, ±1.0-mm accuracy in 128 of 163 (79%) lesions, and ±1.5-mm accuracy in 153 of 163 (94%) lesions. Impedance decrease and electrode temperature were poor predictors of lesion size. There were no detectable lesions resulting from ablation without electrode contact. CONCLUSIONS: Acute PFA ventricular lesions demonstrate irreversible and reversible lesion boundaries. Electrode-tissue contact is required for effective lesion formation. Lesion depth increases significantly with increasing CF and PFA burst pulses. A new exponential/logarithmic formula combined with CF and the number of PFA burst pulses correlates lesion depth with high accuracy.
Asunto(s)
Ablación por Catéter , Animales , Ablación por Catéter/instrumentación , Ablación por Catéter/métodos , Porcinos , Ventrículos Cardíacos/patología , Ventrículos Cardíacos/fisiopatología , Catéteres Cardíacos , Diseño de Equipo , Miocardio/patología , Modelos Animales , Impedancia Eléctrica , Necrosis , Sus scrofa , Temperatura , Factores de Tiempo , Frecuencia CardíacaRESUMEN
BACKGROUND: Pulsed-field ablation (PFA) is a tissue-selective, nonthermal cardiac ablation modality. A novel PFA ablation system consisted of a multichannel irreversible electroporation generator system and a multielectrode circular irreversible electroporation catheter has been developed for catheter ablation. To understand the progression and immediate impacts of PFA, this study evaluated the subchronic (7±3 day) and chronic (30±3 day) safety and performance of the novel PFA system when simulating pulmonary vein and superior vena cava isolation in a porcine beating heart model. METHODS: Ten swine models were divided into subchronic (n=6) and chronic cohorts (n=4). Lesions were performed within the right and left atrium to conduct right pulmonary veins and superior vena cava isolations, in addition to creating stacked lesions in the left atrium roof and right atrium posterior wall. RESULTS: Acute pulmonary vein and superior vena cava isolation were achieved in 10 out of 10 swine and demonstrated 100% lesion durability in both cohorts, including sustained elimination of electrical activity at the left atrium roof and right atrium posterior wall. Histology demonstrated that all the cardiac sites ablated showed discrete zones of loss of myocardial fibers or smooth muscle cells with preservation of the tissue architecture with resultant fibrocellular replacement, neovascularization, and neocollagen deposition. Mineralization findings were present in association with residual necrotic muscle fibers. Only in 7 days group, areas of mineralization were frequently associated with inflammation. There were no treatment-related changes in other tissues, including complete sparing of the phrenic nerve. CONCLUSIONS: Pulsed-field ablation for pulmonary vein and superior vena cava isolation with the novel PFA system was feasible, safe with myocardial-specific ablative effect. Durable lesions were observed at the target areas. with inflammation phenomena mainly documented at 7 days.
Asunto(s)
Fibrilación Atrial , Ablación por Catéter , Venas Pulmonares , Animales , Fibrilación Atrial/cirugía , Ablación por Catéter/efectos adversos , Electroporación , Estudios de Seguimiento , Inflamación , Venas Pulmonares/patología , Venas Pulmonares/cirugía , Porcinos , Vena Cava Superior/patología , Vena Cava Superior/cirugíaRESUMEN
BACKGROUND: Pulsed field ablation (PFA) is a nonthermal energy with potential safety advantages over radiofrequency ablation. This study investigated a novel PFA system-a circular multielectrode catheter (PFA lasso) and a multichannel generator designed to work with Carto 3 mapping system. METHODS: A 7.5F bidirectional circular catheter with 10 electrodes and variable expansion was designed for PFA (biphasic, 1800 Volts). This study included a total of 16 swine used to investigate the following 3 experimental aims: Aim 1 examined the feasibility to create a right atrial ablation line of block from the superior vena cava to the inferior vena cava. Aim 2 examined the effect of PFA on lesion maturation including durability after a 30-day survival period. Aim 3 examined the effect of high-intensity PFA (10 applications) on esophageal and phrenic nerve tissue in comparison to normal intensity radiofrequency ablation (1-2 applications). Histopathologic analysis of all cardiac, esophageal, and phrenic nerve tissue was performed. RESULTS: Acute line of block was achieved in 12/12 swine (100%) and required a total PFA time of 14 seconds (interquartile range [IQR], 9-24.5) per line. Ablation line durability after 28±3 days was maintained in 11/12 (91.7%) swine. PFA resulted in transmural lesions in 179/183 (97.8%) sections and a median lesion width of 14.2 mm. High-intensity PFA (9 [IQR, 8-14] application) had no effect on the esophagus while standard intensity radiofrequency ablation (1.5 [IQR, 1-2] applications) resulted in deep esophageal tissue injury involving the muscularis propria and adventitia layers. High-intensity PFA (16 [IQR, 10-28] applications) has no effect on phrenic nerve function and structure while standard dose radiofrequency ablation (1.5 [IQR, 1-2] applications) resulted in acute phrenic nerve paralysis. CONCLUSIONS: In this preclinical model, a multielectrode circular catheter and multichannel generator produced durable atrial lesions with lower vulnerability to esophageal or phrenic nerve damage.
Asunto(s)
Arritmias Cardíacas/cirugía , Mapeo del Potencial de Superficie Corporal/métodos , Ablación por Catéter/instrumentación , Microelectrodos , Animales , Arritmias Cardíacas/diagnóstico , Arritmias Cardíacas/fisiopatología , Modelos Animales de Enfermedad , Diseño de Equipo , PorcinosRESUMEN
Aims: Delivery of high-power short-duration radiofrequency (RF) ablation lesions is not commonly used, in part because conventional thermocouple (TC) technology underestimates tissue temperature, increasing the risk of steam pop, and thrombus formation. We aimed to test whether utilization of an ablation catheter equipped with a highly accurate novel TC technology could facilitate safe and effective delivery of high-power RF lesions. Methods and results: Adult male Yorkshire swine were used for the study. High-power short-duration ablations (10-s total; 90 W for 4 s followed by 50 W for 6 s) were delivered using an irrigated force sensing catheter, equipped with six miniature TC sensors embedded in the tip electrode shell. Power modulation was automatically performed when the temperature reached 65°C. Ablation parameters were recorded and histopathological analysis was performed to assess lesion formation. One hundred and fourteen RF applications, delivered using the study ablation protocol in the ventricles of eight swine [53 in the right ventricle (RV), 61 in the left ventricle (LV)], were analysed. Average power delivered was 55.4 ± 5.3 W and none of the ablations resulted in a steam pop. Fourteen out of the 114 (12.3%) lesions were transmural. The mean lesion depth was 3.9 ± 1.1 mm for the 100 non-transmural lesions. Similar ablation parameters resulted in bigger impedance drop (11.6 Ω vs. 9.1 Ω, P = 0.009) and deeper lesions in the LV compared with the RV (4.3 ± 1.2 mm vs. 3.3 ± 0.8 mm, P < 0.001). Conclusion: Delivery of high-power short-duration RF energy applications, facilitated by a novel ablation catheter system equipped with advanced TC technology, is feasible, safe, and results in the formation of effective ablation lesions.
Asunto(s)
Catéteres Cardíacos , Ablación por Catéter/instrumentación , Ventrículos Cardíacos/cirugía , Temperatura , Irrigación Terapéutica/instrumentación , Transductores de Presión , Animales , Ablación por Catéter/efectos adversos , Diseño de Equipo , Ventrículos Cardíacos/patología , Masculino , Ensayo de Materiales , Modelos Animales , Vapor , Sus scrofa , Irrigación Terapéutica/efectos adversos , Factores de TiempoRESUMEN
BACKGROUND: Real-time radiofrequency (RF) ablation lesion assessment is a major unmet need in cardiac electrophysiology. OBJECTIVE: The purpose of this study was to assess whether improved temperature measurement using a novel thermocoupling (TC) technology combined with information derived from impedance change, contact force (CF) sensing, and catheter orientation allows accurate real-time prediction of ablation lesion formation. METHODS: RF ablation lesions were delivered in the ventricles of 15 swine using a novel externally irrigated-tip catheter containing 6 miniature TC sensors in addition to force sensing technology. Ablation duration, power, irrigation rate, impedance drop, CF, and temperature from each sensor were recorded. The catheter "orientation factor" was calculated using measurements from the different TC sensors. Information derived from all the sources was included in a mathematical model developed to predict lesion depth and validated against histologic measurements. RESULTS: A total of 143 ablation lesions were delivered to the left ventricle (n = 74) and right ventricle (n = 69). Mean CF applied during the ablations was 14.34 ± 3.55g, and mean impedance drop achieved during the ablations was 17.5 ± 6.41 Ω. Mean difference between predicted and measured ablation lesion depth was 0.72 ± 0.56 mm. In the majority of lesions (91.6%), the difference between estimated and measured depth was ≤1.5 mm. CONCLUSION: Accurate real-time prediction of RF lesion depth is feasible using a novel ablation catheter-based system in conjunction with a mathematical prediction model, combining elaborate temperature measurements with information derived from catheter orientation, CF sensing, impedance change, and additional ablation parameters.