Multi-layer braided structures for occluding vascular defects

A collapsible medical device and associated methods of occluding an abnormal opening in, for example, a body organ, wherein the medical device is shaped from plural layers of a heat-treatable metal fabric. Each of the fabric layers is formed from a plurality of metal strands and the assembly is heat-treated within a mold in order to substantially set a desired shape of the device. By incorporating plural layers in the thus-formed medical device, the ability of the device to rapidly occlude an abnormal opening in a body organ is significantly improved.