Abstract: An inflatable device (1) for use within the vasculature of a body and having an expandable annular body (Ia) which is expandable by inflation of a series of inflation lumen (2) defined therein, the device having inflated (b) and non-inflated (a) states and inner (3) and outer (4) annular walls, the device being adapted so that inflationary pressure within the lumen moves the device from the non-inflated state toward the inflated state by radially outward expansion of both the outer and inner walls so that the annular body expands to form an annular structure with a central lumen defined by the inner wall (3). Non-compliant or semi-compliant balloons (36) are provided in the inflation lumen (2). The device may be employed as an embolic filter or an introducer catheter.