Disclosed is a constraining mechanism that enhances the strength of a medical device, while also preventing over expansion of the device, during a procedure. The medical device includes a plurality of biased struts to which a constraining mechanism is coupled. The constraining mechanism includes a spine, which couples to one of the plurality of struts, and one or more branches extending from the spine. The branches have a curvature enabling the branches to substantially surround the plurality of struts while at the same time avoiding contact with the wall of the blood vessel of the patient when the medical device is deployed.