An intravascular valve component comprising: a valve case including attached proximal and distal case portions (18, 22), said case portions presenting respective spaced apart fluid ports and a fluid passageway (54, 100) extending between the ports along a valve axis when said case portions (18, 22) are attached; and a flexible fluid pressure-actuated flow control valve disposed along the fluid passageway (54, 100) to control fluid flow therethrough, said valve including a substantially dome shaped central valve wall having a slit and an annular flange surrounding the central valve wall, said dome-shaped central valve wall having a concave surface and a convex surface, said annular flange including a radially-extending flange wall having a radially outermost edge, wherein the valve is configured to selectively open and close dependent on a fluid pressure differential across the respective concave and convex surfaces, said intravascular valve component characterized by: a valve-seating projection extending axially from the flange wall and spaced radially outwardly from said valve wall and between said outermost edge and the valve wall to permit said slit to flex between open infusion and aspiration configurations, one of said case portions (18,22) presenting a projection-receiving opening,said flange wall being engagingly received between the attached case portions (18, 22), wherein the projection-receiving opening is complementally shaped to the valve-seating projection to thereby interfit the projection within the opening to restrict radial movement of the flow control valve relative to the valve case (18, 22) and to coaxially align the valve with one of the case portions (18, 22) presenting said opening to thereby position the valve wall concentrically within the fluid passageway (54, 100). a valve case including attached proximal and distal case portions (18, 22), said case portions presenting respective spaced apart fluid ports and a fluid passageway (54, 100) extending between the ports along a valve axis when said case portions (18, 22) are attached; and a flexible fluid pressure-actuated flow control valve disposed along the fluid passageway (54, 100) to control fluid flow therethrough, said valve including a substantially dome shaped central valve wall having a slit and an annular flange surrounding the central valve wall, said dome-shaped central valve wall having a concave surface and a convex surface, said annular flange including a radially-extending flange wall having a radially outermost edge, wherein the valve is configured to selectively open and close dependent on a fluid pressure differential across the respective concave and convex surfaces, said intravascular valve component characterized by: a valve-seating projection extending axially from the flange wall and spaced radially outwardly from said valve wall and between said outermost edge and the valve wall to permit said slit to flex between open infusion and aspiration configurations, one of said case portions (18,22) presenting a projection-receiving opening,said flange wall being engagingly received between the attached case portions (18, 22), wherein the projection-receiving opening is complementally shaped to the valve-seating projection to thereby interfit the projection within the opening to restrict radial movement of the flow control valve relative to the valve case (18, 22) and to coaxially align the valve with one of the case portions (18, 22) presenting said opening to thereby position the valve wall concentrically within the fluid passageway (54, 100). a valve-seating projection extending axially from the flange wall and spaced radially outwardly from said valve wall and between said outermost edge and the valve wall to permit said slit to flex between open infusion and aspiration configurations, one of said case portions (18,22) presenting a projection-receiving opening,said flange wall being engagingly received between the attached case portions (18, 22), wherein the projection-receiving opening is complementally shaped to the valve-seating projection to thereby interfit the projection within the opening to restrict radial movement of the flow control valve relative to the valve case (18, 22) and to coaxially align the valve with one of the case portions (18, 22) presenting said opening to thereby position the valve wall concentrically within the fluid passageway (54, 100).