Radiofrequency Endothelial Ablation Prevents Recanalization after Endovascular Coil Occlusion: In Vitro and in Vivo Assessment

Purpose

Coil embolization of intracranial aneurysms may be followed by recurrences. Radiofrequency (RF) ablation of the endothelium may prevent recanalization after coil embolization.

Materials and Methods

The authors performed in vitro experiments in chicken meat and egg white models to investigate the thermal distribution and geometry of lesions created with RF applied through standard coils alone or by using a prototype RF electrode inserted in a coil or a mass of coils. A mathematic model was designed to predict perianeurysmal isotherm lesions by using the bio-heat equation. In an in vivo coil arterial occlusion model (six dogs), the authors compared angiographic and pathologic results of coil embolization (n = 8) with those of coil embolization preceded by RF ablation (n = 7) by using a cardiac electrode at 1 month.

Results

Current coils offer high impedance (400 Ω) at high current frequencies and are damaged by RF transmission. A dedicated electrode generated reproducible lesions, but contact with coils interferes with lesion reproducibility. When the coil mass was used, a uniform RF lesion that conformed to the coil mass shape was produced. The mathematic model predicted a uniform heat distribution within 1 mm from the coil mass periphery. Arterial coil embolization led to occlusion followed by recanalization (n = 8), whereas RF ablation (20–30 W for 60 seconds) prevented recanalization in all coil-occluded arteries (P < .001, χ² test). Pathologic findings helped confirm complete arterial occlusion with RF ablation. One animal developed brachial plexus injury with excessive levels of RF ablation.

Conclusions

RF ablation can prevent recanalization after coil occlusion—at least in the arterial model. Modifications of coils, dedicated neurovascular electrodes, and technique optimization remain necessary before considering a clinical application.

Abbreviation: RF, radiofrequency