A pre-clinical animal study of a novel mechanical-only ablation device treatment for superficial venous disease

OBJECTIVE

Current minimally invasive techniques for ablation in superficial venous reflux are limited to thermal based systems requiring tumescent anesthesia, non-thermal chemical sclerosants and permanent glue implantation. The aim of this feasibility study was to determine the safety and efficacy of a novel mechanical-only ablation (MOA) device called EnVena, in a recognised large animal model with chronic follow up.

METHODS

Venous ablation of six lateral saphenous veins in three sheep was performed using the EnVena device. Luminal patency and vein wall fibrosis were evaluated by histologic analysis at 51 and 89 days.

RESULTS

All treated veins demonstrated fibrotic occlusion in contiguous segments at 51 and 89 days on histological analysis. From 45 consecutive segments spanning the treatment length across the six treated veins, 26 (57%) were fully occluded, 7 (16%) were impinged or partially occluded and 12 (27%) were open. There were no device related complications during the follow up period.

CONCLUSIONS

A purely mechanical approach to superficial venous ablation demonstrated safety and efficacy in a recognized large animal model based on histological findings.

Two-Year Follow-Up after Endovenous Closure with Short-Chain Cyanoacrylate versus Laser Ablation in Venous Insufficiency

Background: The current treatment of venous disease is focused on the minimally invasive exclusion of the affected vein. Besides widely used thermal ablation, chemical ablation with cyanoacrylate, reported as safe and highly effective, has been gaining increasing interest. Patients and methods: In the current report, we present data from a two-year observation in 89 patients (61 female/28 male, mean age 44.3 ± 13.5) suffering from venous insufficiency (C2–C4), treated either using short-chain cyanoacrylate, the VenaBlock system (n = 43) or laser thermoablation with ELVeS 1470 (n = 46). The assessment comprised the occurrence of venous disease-related symptoms and the ultrasound examination of the leg venous system. Results: The frequency of recanalization after 2 years from the VenaBlock procedure was significantly higher than after laser treatment (37.2 vs. 8.7%). Apart from recanalization, in some individuals from both groups, the symptoms of recurrence and/or disease progression, including the development of insufficiency in other veins of treated or contralateral legs (9.3 vs. 15.2% and 9.3 vs. 17.4%, respectively), were observed. Unexpectedly, the general prevalence of the disease progression did not differ significantly between the VenaBlock and ELVeS groups (44.2 vs. 34.8%, respectively). Conclusions: Despite the higher recanalization rate of VenaBlock compared to ELVeS, the overall effectiveness of cyanoacrylate and laser thermoablation after two years was similar. Therefore, both methods similarly failed to prevent recurrence and disease progression, which seem to be method-independent.

Implications and considerations of thermal effects when applying irreversible electroporation tissue ablation therapy

Irreversible electroporation (IRE) describes a cellular response to electric field exposure, resulting in the formation of nanoscale defects that can lead to cell death. While this behavior occurs independently of thermally-induced processes, therapeutic ablation of targeted tissues with IRE uses a series of brief electric pulses, whose parameters result in secondary Joule heating of the tissue. Where contemporary clinical pulse protocols use aggressive energy regimes, additional evidence is supplementing original studies that assert care must be taken in clinical ablation protocols to ensure the cumulative thermal effects do not induce damage that will alter outcomes for therapies using the IRE non-thermal cell death process for tissue ablation. In this letter, we seek to clarify the nomenclature regarding IRE as a non-thermal ablation technique, as well as identify existing literature that uses experimental, clinical, and numerical results to discretely address and evaluate the thermal considerations relevant when applying IRE in clinical scenarios, including several approaches for reducing these effects. Existing evidence in the literature describes cell response to electric fields, suggesting cell death from IRE is a unique process, independent from traditional thermal damage. Numerical simulations, as well as preclinical and clinical findings demonstrate the ability to deliver therapeutic IRE ablation without occurrence of morbidity associated with thermal therapies. Clinical IRE therapy generates thermal effects, which may moderate the non-thermal aspects of IRE ablation. Appropriate protocol development, utilization, and pulse delivery devices may be implemented to restrain these effects and maintain IRE as the vastly predominant tissue death modality, reducing therapy-mitigating thermal damage. Clinical applications of IRE should consider thermal effects and employ protocols to ensure safe and effective therapy delivery.