this invention is an apparatus for creating an endovascular occlusion by the formation of thrombi in arteries , veins , aneurysms , vascular malformations , and arteriovenous fistulas . in particular , the invention is an assembly for electrolytically severing a portion of the endovascular device such as a coil via the use of electrolysis . the vasoocclusive device is introduced through a catheter and is intended to remain at the desired thrombus formation site . the invention further includes a method for the introduction of the device and its electrolytic separation .