Systems and devices with an implantable, intravascular filter for preventing emboli from traveling into brain and causing a stroke or transient ischemic attack are disclosed. In particular, an implantable, intravascular device having a filter element, a pressure sensor, and a valve is disclosed. The valve is biased into a closed configuration and changes into an open configuration upon a predetermined pressure drop across the filter. Systems comprising an external device at least one implantable device are also disclosed.
