<p>The present invention relates to apparatus for retroperfusion of tissues and organs. The apparatus comprises a catheter with a proximal end for engaging a supply of the fluid medium, and a distal end having an expandable-contractible chamber for installation into suitable vessels or organs. The expandable-contractible chamber comprises a conduit element having a fluid- filled hollow wall defining a lumen. The conduit element has a first deformable inner-facing section approximate a proximal end of the conduit and a second deformable inner-facing section approximate a distal end of the conduit element. Controlled application of a pressure at a proximal end of the conduit element causes deformation of the conduit into the lumen at its distal end thereby occluding the flow of fluid medium through the catheter. Controlled release of the pressure releases deformation of the fluid-filled conduit at its distal end thereby unblocking the flow of the fluid medium through the catheter.</p>
