Abstract: A tubular graft comprising an internal helical formation which imparts helical flow on fluid passing through the tubular graft. One end of the tubular graft is tapered from an inner base to an outer tip.

Abstract: A tubular conduit is disclosed. The tubular conduit comprises a tubular portion made from a flexible material and an axially extending external helical formation located around the outside of the tubular portion. The external helical formation is for supporting the tubular portion. Optionally the tubular portion also comprises an axially extending internal helical protrusion, which imparts a helical flow to a fluid passing through the tubular portion. It is preferred that the tubular conduit is a vascular graft.

Abstract: A tubular conduit is disclosed. The tubular conduit comprises a tubular portion made from a flexible material and an axially extending external helical formation located around the outside of the tubular portion. The external helical formation is for supporting the tubular portion. Optionally the tubular portion also comprises an axially extending internal helical protrusion, which imparts a helical flow to a fluid passing through the tubular portion. It is preferred that the tubular conduit is a vascular graft.

Abstract: A vascular access graft comprises an elongate conduit having proximal and distal ends. At least a portion of the elongate conduit has a self-sealing property such that the portion remains impermeable after puncturing by a dialysis needle. The vascular access graft also comprises a helical fin projecting inwardly from the inner surface of the elongate conduit and extending parallel to the axis of the elongate conduit.

Abstract: A vascular access graft (1) comprises an elongate conduit (2) having proximal and distal ends (3, 4). At least a portion of the elongate conduit (2) has a self-sealing property such that the portion remains impermeable after puncturing by a dialysis needle. The vascular access graft (1) also comprises a helical fin (6) projecting inwardly from the inner surface (5) of the elongate conduit (2) and extending parallel to the axis of the elongate conduit (2).

Abstract: A tubular conduit is disclosed. The tubular conduit comprises a tubular portion made from a flexible material and an axially extending external helical formation located around the outside of the tubular portion. The external helical formation is for supporting the tubular portion. Optionally the tubular portion also comprises an axially extending internal helical protrusion, which imparts a helical flow to a fluid passing through the tubular portion. It is preferred that the tubular conduit is a vascular graft.

Abstract: A tubular graft comprising an internal helical formation which imparts helical flow on fluid passing through the tubular graft. One end of the tubular graft is tapered from an inner base to an outer tip.

Abstract: A tubular graft comprising an internal helical formation which imparts helical flow on fluid passing through the tubular graft. One end of the tubular graft is tapered from an inner base to an outer tip.

Abstract: An internal formation for a conduit. The formation has a longitudinally extending member adapted to extend along an inside surface of at least a portion of the length of the conduit. The longitudinally extending member has an asymmetric profile in a direction transverse of the longitudinal axis of the member.

Abstract: A tubular conduit (1) is disclosed. The tubular conduit comprises a tubular portion made from a flexible material and an axially extending external helical formation (16) located around the outside of the tubular portion. The external helical formation (16) is for supporting the tubular portion. Optionally the tubular portion also comprises an axially extending internal helical protrusion (15), which imparts a helical flow to a fluid passing through the tubular portion. It is preferred that the tubular conduit (1) is a vascular graft.

Abstract: A vascular access graft (1) comprises an elongate conduit (2) having proximal and distal ends (3, 4). At least a portion of the elongate conduit (2) has a self-sealing property such that the portion remains impermeable after puncturing by a dialysis needle. The vascular access graft (1) also comprises a helical fin (6) projecting inwardly from the inner surface (5) of the elongate conduit (2) and extending parallel to the axis of the elongate conduit (2).

Abstract: There is disclosed an insert (2) for a conduit (4) adapted to effect helical flow in the conduit (4) comprising a longitudinally extending member having a helical formation.

Abstract: There is disclosed a method for introducing a helical formation (11) into a flexible tubular material (12). The material (12) is supported together with a surrounding helical former (13) so as to deform the material (12) to have a helical indentation (11) corresponding to the shape of the former (13). The material (12) is then set in that configuration and the former (13) is removed.

Abstract: A tubular graft (1) comprises an elongate conduit (2) having distal and proximal ends (3, 4). The tubular graft (1) also comprises a helical fin (10) projecting inwardly from the inner surface of the elongate conduit (2) and extending parallel to the axis of the elongate conduit (2). The helical fin (10) extends from the distal end (3) of the elongate conduit (2) to a point (11) short of the proximal end (4) of the elongate conduit (2).

Abstract: A helical formation within a conduit and a method of determining the helix angle of the helical formation are disclosed. The method includes specifying the internal dimensions of the conduit and an intended fluid mass flow through the conduit. The helix angle is determined from the pressure drop and the turbulent kinetic energy for a conduit having the specified internal dimensions and intended fluid mass flow.

Abstract: A Method of Determining the Helix Angle of a Helical Formation for a Conduit. A method of determining the helix angle of a helical formation (4) within a conduit (1). The method includes specifying the internal dimensions of the conduit (1) and an intended fluid mass flow through the conduit (1). The helix angle is determined from the pressure drop and the turbulent kinetic energy for a conduit (1) having the specified internal dimensions and intended fluid mass flow.

Abstract: A method of assessing the effect of a conduit section (11) on flow characteristics of a first fluid in a first conduit system (1). A first fluid is caused to flow through the first conduit system (1). A transverse flow parameter of the first fluid in the first conduit system (1) downstream of the conduit section (11) is detected. At least one transverse flow characteristic of the first fluid is determined from the detected transverse flow parameter. The effect of the conduit section (11) is then assessed from the determined flow characteristics.

Abstract: There is disclosed a method for introducing a helical formation (11) into a flexible tubular material (12). The material (12) is supported together with a surrounding helical former (13) so as to deform the material (12) to have a helical indentation (11) corresponding to the shape of the former (13). The material (12) is then set in that configuration and the former (13) is removed.

Abstract: There is disclosed an insert (2) for a conduit (4) adapted to effect helical flow in the conduit (4) comprising a longitudinally extending member having a helical formation.