Preclinical evaluation of a novel single-shot pulsed field ablation system for pulmonary vein and atrial ablation

First-in-human experience of high-energy ElectroPulse pulsed field ablation: Acute results for pulmonary veins and posterior wall isolation

BACKGROUND

Different iterations of catheter and energy delivery system configurations are evolving for pulsed field ablation (PFA); however, some have used large and complex catheters, required large sheaths, and had a recognized risk of hemolysis.

OBJECTIVE

The purpose of this study was to evaluate the acute safety and efficacy of a custom designed 8F variable loop multielectrode mapping and PFA catheter with contact sensing.

METHODS

This acute feasibility study recruited 30 patients undergoing de novo ablation of paroxysmal or persistent atrial fibrillation (AF). The ElectroPulse Study is a first-in-human, nonrandomized, prospective study of a novel PFA system that utilizes an 8F, 10-electrode variable loop steerable mapping and ablation catheter with 2800-V biphasic bipolar waveform. All patients had pulmonary vein isolation (PVI) and posterior wall isolation (PWI) using the PFA system. The main outcomes were the acute success of PV/PWI and periprocedural serious adverse events.

RESULTS

Complete PVI/PWI was successfully achieved in all 30 patients using 59.7 ± 7.2 applications. Total procedural time was 113.6 ± 26.3 minutes, fluoroscopy time 8.0 ± 5.5 minutes, and left atrial dwell time 78.7 ± 18.6 minutes. There was no esophageal injury, phrenic nerve palsy, clinical stroke, or death. Brain magnetic resonance imaging detected 2 new but transient silent cerebral lesions. Two patients (6.7%) had vascular access complications. Although there were changes in the biomarkers for hemolysis, none of the patients experienced clinical hemolysis or related acute kidney injury.

CONCLUSION

This first-in-human study demonstrated that PFA using a novel variable loop catheter with a contact sensing system safely achieved 100% acute PVI/PWI with safety profile comparable to existing PFA systems.

Ablating Myocardium Using Nanosecond Pulsed Electric Fields: Preclinical Assessment of Feasibility, Safety, and Durability

BACKGROUND

Unlike conventional microsecond pulsed electrical fields that primarily target the cell membranes, nanosecond pulses are thought to primarily electroporate intracellular organelles. We conducted a comprehensive preclinical assessment of catheter-based endocardial nanosecond pulsed field ablation in swine.

METHODS

A novel endocardial nanosecond pulsed field ablation system was evaluated in a total of 25 swine. Using either a low-dose (5-second duration) or high-dose (15-second duration) strategy, thoracic veins and discrete atrial and ventricular sites were ablated. Predetermined survival periods were <1 (n=1), ≈2 (n=7), ≈7 (n=6), 14 (n=2), or ≈28 (n=9) days, and venous isolation was assessed before euthanasia. Safety assessments included evaluation of esophageal effects, phrenic nerve function, and changes in venous caliber. All tissues were subject to careful gross pathological and histopathologic examination.

RESULTS

All (100%) veins (13 low-dose, 34 high-dose) were acutely isolated, and all reassessed veins (6 low-dose, 15 high-dose) were durably isolated. All examined vein lesions (10 low-dose, 22 high-dose) were transmural. Vein diameters (n=15) were not significantly changed. Of the animals assessed for phrenic palsy (n=9), 3 (33%) demonstrated only transient palsy. There were no differences between dosing strategies. Thirteen mitral isthmus lesions were analyzed, and all 13 (100%) were transmural (depth, 6.4±0.4 mm). Ventricular lesions were 14.7±4.5 mm wide and 7.1±1.3 mm deep, with high-dose lesions deeper than low-dose (7.9±1.2 versus 6.2±0.8 mm; P=0.007). The esophagus revealed nontransmural adventitial surface lesions in 5 of 5 (100%) animals euthanized early (2 days) post-ablation. In the 10 animals euthanized later (14-28 days), all animals demonstrated significant esophageal healing-8 with complete resolution, and 2 with only trace fibrosis.

CONCLUSIONS

A novel, endocardial nanosecond pulsed field ablation system provides acute and durable venous isolation and linear lesions. Transient phrenic injury and nontransmural esophageal lesions can occur with worst-case assessments suggesting limits to pulsed field ablation tissue selectivity and the need for dedicated assessments during clinical studies.

Opportunities and Challenges in Catheter-Based Irreversible Electroporation for Ventricular Tachycardia

The use of catheter-based irreversible electroporation in clinical cardiac laboratories, termed pulsed-field ablation (PFA), is gaining international momentum among cardiac electrophysiology proceduralists for the non-thermal management of both atrial and ventricular tachyrhythmogenic substrates. One area of potential application for PFA is in the mitigation of ventricular tachycardia (VT) risk in the setting of ischemia-mediated myocardial fibrosis, as evidenced by recently published clinical case reports. The efficacy of tissue electroporation has been documented in other branches of science and medicine; however, ventricular PFA's potential advantages and pitfalls are less understood. This comprehensive review will briefly summarize the pathophysiological mechanisms underlying VT and then summarize the pre-clinical and adult clinical data published to date on PFA's effectiveness in treating monomorphic VT. These data will be contrasted with the effectiveness ascribed to thermal cardiac ablation modalities to treat VT, namely radiofrequency energy and liquid nitrogen-based cryoablation.

A novel pulsed field ablation system using linear and spiral ablation catheters can create large and durable endocardial and epicardial ventricular lesions in vivo

BACKGROUND

We investigated the preclinical safety and efficacy of ventricular pulsed field ablation (PFA) using a family of novel, 6-/8-Fr, linear, and spiral PFA/mapping catheters (CRC EP, Inc).

METHODS

QRS-gated, bipolar PFA (>2.0 kV) was performed in 10 healthy swine. Altogether, 20 endocardial and epicardial right and left ventricular applications were delivered. The catheters were inserted through an 8.5-Fr steerable introducer. The intensity of skeletal muscle activation was quantified using an accelerometer. Lesions were assessed by pre- versus post-PFA electrogram analysis, pacing threshold, 3D voltage mapping, necropsy, and histology. The swine rete mirabile, liver and kidneys were examined for embolic events.

RESULTS

All applications were single-shot (56 ± 18 s) without catheter repositioning. Minimal microbubbling was observed without significant skeletal muscle stimulation (mean acceleration 0.05 m/s2) or ventricular tachyarrhythmias. There was significant reduction in post- versus pre-PFA electrogram amplitude (0.5 ± 0.2 mV versus 3.2 ± 0.9 mV, P < 0.001) with a marked increase in pacing threshold (>20 mA versus 7.5 ± 2.9 mA, P < 0.001). All lesions were large and durable up to 28 days, measuring 32 ± 5 mm (length), 27 ± 8 mm (width), and 8 ± 3 mm (depth) using the spiral catheters and 43 ± 1 mm (length), 7 ± 1 mm (width), and 8 ± 1 mm (depth) using the linear catheters. Despite higher waveform voltages and prolonged applications, no thermal effects were detected at necropsy/histology. Moreover, gross and microscopic examinations revealed no evidence of thromboembolism, vascular or collateral injury.

CONCLUSIONS

A novel, QRS-gated PFA system using linear and spiral PFA catheters is capable of creating large and durable ventricular lesions in vivo without significant microbubbling, ventricular arrhythmias or thromboembolism.