An endovascular microvalve device for temporary use in a vessel of a patient during an intravascular procedure, the vessel having a vessel wall, comprising: a) a flexible catheter sized for introduction into the vessel, the catheter having a proximal end and a distal end, an outer surface, a lumen extending between the proximal and distal ends (1310, 1312), and opening at a distal orifice; and b) a filter valve having a proximal end and distal end, the filter valve including a plurality of filamentary strands each having a proximal portion, a central portion, and a distal portion, the proximal portions of the strands fixed to the outer surface of the catheter at a location proximal of the orifice, the central portions of the strands extending radially outward from the outer surface and toward the orifice, and the distal portions of the strands inverting back into the filter valve and to the outer surface of the catheter, the distal portions coupled to the outer surface of the catheter, wherein once the filter valve is in a deployed state in the vessel, the filter valve is dynamically movable depending on local fluid pressure conditions about the filter valve, such that, when the fluid pressure is higher on a proximal side of the filter valve, the filter valve assumes a first configuration with a first diameter smaller than the diameter of the vessel such that flow about the filter valve and through the vessel in a proximal to distal direction is permitted, and when the fluid pressure is higher on a distal side of the filter valve, the filter valve assumes a second configuration with a second diameter relatively larger than the first diameter and in which the filter valve is adapted to contact the vessel wall to act as a barrier to flow about the filter valve and through the vessel in a distal to proximal direction. a) a flexible catheter sized for introduction into the vessel, the catheter having a proximal end and a distal end, an outer surface, a lumen extending between the proximal and distal ends (1310, 1312), and opening at a distal orifice; and b) a filter valve having a proximal end and distal end, the filter valve including a plurality of filamentary strands each having a proximal portion, a central portion, and a distal portion, the proximal portions of the strands fixed to the outer surface of the catheter at a location proximal of the orifice, the central portions of the strands extending radially outward from the outer surface and toward the orifice, and the distal portions of the strands inverting back into the filter valve and to the outer surface of the catheter, the distal portions coupled to the outer surface of the catheter, wherein once the filter valve is in a deployed state in the vessel, the filter valve is dynamically movable depending on local fluid pressure conditions about the filter valve, such that, when the fluid pressure is higher on a proximal side of the filter valve, the filter valve assumes a first configuration with a first diameter smaller than the diameter of the vessel such that flow about the filter valve and through the vessel in a proximal to distal direction is permitted, and when the fluid pressure is higher on a distal side of the filter valve, the filter valve assumes a second configuration with a second diameter relatively larger than the first diameter and in which the filter valve is adapted to contact the vessel wall to act as a barrier to flow about the filter valve and through the vessel in a distal to proximal direction. wherein once the filter valve is in a deployed state in the vessel, the filter valve is dynamically movable depending on local fluid pressure conditions about the filter valve, such that, when the fluid pressure is higher on a proximal side of the filter valve, the filter valve assumes a first configuration with a first diameter smaller than the diameter of the vessel such that flow about the filter valve and through the vessel in a proximal to distal direction is permitted, and when the fluid pressure is higher on a distal side of the filter valve, the filter valve assumes a second configuration with a second diameter relatively larger than the first diameter and in which the filter valve is adapted to contact the vessel wall to act as a barrier to flow about the filter valve and through the vessel in a distal to proximal direction.