Abstract: In an improved process for immobilizing a chelator moiety on a silica substrate, the substrate is reacted in a liquid reaction medium with an alkyltrialkoxysilane compound having a functional group that provides an attachment site for covalently binding the chelator moiety to the substrate. The improvement comprises providing a particulate silica substrate having a surface area of less than about 50 m.sup.2 /g. An improved extracorporeal device for removing metal ions from blood and other fluids includes a cartridge having an inlet and an outlet and containing a plurality of tubular fibers that extend from the inlet to the outlet. Each fiber has a lumen enclosed by an anisotropic membrane. The membrane is supported by a macroporous structure that contains a chelator moiety immobilized on a particulate silica substrate having a surface area of less than about 50 m.sup.2 /g.

Abstract: Suture rings are provided for heart valves having surrounding stiffening protrusions that are either integral parts of the heart valve bodies or are rigid rings held in interference fit within peripheral grooves of heart valve bodies. Metal retainer rings engage the stiffening protrusions to lock the retainer rings to the valve bodies and carry fabric coverings on their exterior surfaces that are suturable to the heart tissues. Deformable portions of the retainer rings are used to provide engagement between the retainer rings and the protrusions and also to permanently position bands that secure the fabric coverings to the retainer rings.

Abstract: Heart valve prostheses have annular valve bodies with central passageways and valve members supported for pivotal and translational movement between open and closed positions. The occluders, which may be either of a bileaflet or single occluder design, are supported within the bodies by pairs of ears extending from opposite locations to interengage with corresponding arcuate depressions to guide the occluders between their closed positions where they seat against upstream protuberances of the valve bodies and their open position where they are positioned between the upstream protuberances and downstream protuberances.

Abstract: A heart valve having a pair of leaflets which are guided between their open and closed positions by guides extending outward and received in dog-leg shaped depressions. The depressions each have a downstream section, which angles outward from a centerline plane of the valve body and a connected vertical upstream section. In the closed position the guides reside in intermediate locations to unload the force between the guides and the depression walls.

Abstract: Heart valves having valve members which are guided between their open and closed positions by projections extending inward from the annular body and interengaging with complementary notches in the peripheries of the occluders. Protuberances associated with the projections cooperate to define the pivotal axes, serve as open and closed position stops, and retain the valve members within the valve body.

Abstract: Double-leaflet heart valves having improved flow through the orifice defined by an annular valve body include a pair of leaflets which may be arcuate or flat in cross section. Guides protrude oppositely from the leaflets and are received in complementary depressions in the interior wall surface of a pair of standards which extend downstream from the annular valve body at generally diametrically opposite locations. The depressions are preferably elongated so that, as the leaflets pivot between the open and closed positions, the guides move from one end of the elongated depressions to the other. Eccentric pivot axes provide for quick response of the leaflets, and the location of the depressions in the standards moves the leaflets out of the annular valve body, reducing resistance to the free flow of blood therethrough.

Abstract: A heart valve has an elliptical occluder mounted for pivoting in an annular heart valve body with a circular passageway between an open position to allow blood flow through the passageway and a closed position to block blood flow. A pair of ears extend from the occluder into a pair of opposed pie-shaped depressions in the interior wall of the valve body so that the relative rotation of the ears along the verticies of the depressions defines an eccentric pivot axis. The occluder seats in its closed position against a lip which protrudes inward of the interior wall on the major side of the eccentric axis.

Abstract: Single or double-leaflet heart valves include leaflet valve members which are arcuate in cross section, preferably being essentially a portion of the wall of a circular tube. Generally spherical sectors protrude oppositely from the leaflets and are received in elongated, complementary depressions in the interior wall of the annular valve body at generally diametrically opposite locations. As the leaflets pivot between the open and closed positions, the guides move from one end of the elongated depressions to the other. Eccentric pivot axes provide for quick response of the leaflets, and their arcuate shape coupled with shifting of the axes during pivoting moves the leaflets out of the center of the valve passageway reducing resistance to the free flow of blood.