Feasibility of Catheter-Directed Intraluminal Irreversible Electroporation of Porcine Ureter and Acute Outcomes in Response to Increasing Energy Delivery

Abstract

Purpose To evaluate the feasibility of focal intraluminal irreversible electroporation (IRE) in the ureter with a novel electrode catheter and to study the treatment effects in response to increasing pulse strength. Material and Methods Five IRE treatment settings were each evaluated twice for the ablation of normal ureter in five Yorkshire pigs (1–4 ablations/animal, total of 10 ablations) using a prototype device under ultrasound and fluoroscopic guidance. Animals received either unilateral or bilateral treatment, limited to a maximum of two ablations in any one ureter. Treatment was delivered with increasing pulse strength (1000V–3000V; increments of 500V) while keeping the pulse duration (100 µseconds) and number of pulses (90) constant. Ureter patency was assessed immediately following treatment with an antegrade ureteropyelography. Animals were sacrificed within 4 hours following treatment, and treated urinary tract was harvested for histopathologic analysis using hematoxylin and eosin (H&E) and Masson’s Trichrome (MT) stains. Results IRE was successfully performed in all animals without evidence of ureteral perforation. H&E analysis of IRE treatments demonstrated full thickness ablation at higher field strengths (mucosa to the adventitia). MT stains showed preservation of connective tissue at all field strengths. Conclusion Intraluminal catheter directed IRE ablation is feasible and produces full thickness ablation of normal ureters. There was no evidence of lumen perforation even at the maximum voltages evaluated in the study.

Normal Porcine Ureter Retains Lumen Wall Integrity but Not Patency Following Catheter-Directed Irreversible Electroporation: Imaging and Histologic Assessment over 28 Days

“…Electric pulses (90 pulses at 2000 V, 100 μs) were delivered between the monopolar electrode (15 mm exposure) and grounding pad affixed to the shaved flank following techniques previously reported by Srimathveeravalli et al 15 . These pulse parameters were identified in prior work as the lowest energy setting for uniform, full thickness IRE of the normal porcine ureter 15 .…”

“…These pulse parameters were identified in prior work as the lowest energy setting for uniform, full thickness IRE of the normal porcine ureter 15 . A neuromuscular paralytic, rocuronium (0.7–0.12 mg/kg), was administered before delivering pulses.…”

“…An average of 5 regions of interest, each measuring 567,162 μm 2 , was acquired from each sample. Semi-quantitative scoring followed techniques reported by Srimathveeravalli et al 15 , where, on a scale 0– 4, 0 marked complete absence of a finding and 4 marked presence of a finding in the entire field being analyzed. Intermediary scores were graded as, 1 (<25%), 2 (<50%) and 3 (<75%), contingent on increased presence of findings.…”

“…However, sharp applicator-based IRE devices are not well suited for endoscopic or focal image-guided ablation of UUTC. A catheter-mounted electrode has been developed for the purpose of performing intraluminal IRE 15 . This device can be used under ureteroscopic or fluoroscopic guidance for focal tumor ablation.…”

Electrical and thermal analyses of catheter-based irreversible electroporation of digestive tract

“…Currently, there are no commercially available catheter-based electrodes for IRE in clinical practice. The electrodes used in animal studies were based on or modified from RFA catheters [16,20,21]. Although experimental studies have demonstrated the safety and efficacy of these electrodes, the relationship between the electrode configuration and ablation zone remains undetermined.…”