Current Operating Procedure (COP) for the Treatment of Slow-Flow Vascular Malformations with Bleomycin Electrosclerotherapy (BEST).

Bleomycin electrosclerotherapy (BEST) is an emerging, minimally invasive treatment for treating slow-flow vascular malformations. Following intralesional administration of bleomycin, reversible electroporation is applied to enhance drug uptake and prolong local exposure due to a vascular lock effect and endothelial disruption. The procedure is based on electrochemotherapy principles, which have shown selective sensitivity of dysplastic and proliferative endothelium. Clinical experience indicates that BEST achieves effective lesion reduction with lower cumulative bleomycin doses and fewer treatment sessions compared to conventional Bleomycin sclerotherapy. This article presents a standardized protocol based on the current operating procedure (COP) developed by the International Network for Sharing Practices on Electrochemotherapy (InspECT) and collaborating centers. Sections cover patient selection, pre-treatment imaging, anesthesia considerations, lesion access, drug preparation, optimal dosing, electrode selection, electrical parameters, and post-procedural care. The protocol supports ultrasound-guided interventions and uses Cliniporator-validated European Standard Operating Procedures of Electrochemotherapy (ESOPE) pulse parameters. BEST is especially suitable for venous, lymphatic, capillary, and mixed slow-flow malformations where intralesional injection and safe electrode placement are possible. The method offers benefits for primary, resistant, or recurrent lesions and may significantly reduce disease burden. This protocol is intended to facilitate reproducible implementation of BEST across clinical centers and serves as a foundation for future refinement toward a fully validated standard operating procedure (SOP).