A system for treating a wide-neck aneurysm comprising a mesh-like sleeve fabricated from a class of polymer filaments that carry conductive particles therein to provide the filaments with a specified resistivity. The releasable mesh-like sleeve is introduced to the site of a targeted vascular malformation by the working end of a catheter that carries an electrode arrangement at its distal terminus. The system further provides an electrical source and controller (i) that modulates power delivery to the polymer matrix which can then fuse the sleeve to the wall of a blood vessel to span across the vascular malformation.