Blood-flow tubing
An artificial or modified natural blood flow tubing has a helical-flow inducer to induce helical flow in such a fashion as to eliminate or reduce turbulence. One inducer is a tubular stent of expansible mesh having a helical vane.
1. A method of inducing helical flow comprising the use of helical flow inducing tubing comprising at least two internal helical ridges, at least two internal helical grooves, or both at least two internal helical ridges and at least two internal helical grooves, configured in such a fashion as to eliminate or reduce turbulence in the tubing, wherein, at each of at least one cross-section of the tubing, taken on a plane normal to the longitudinal axis of the tubing, each helical ridge, each groove, or each helical ridge and each groove is located at a different point of the circumference of the tubing wherein at least one of the internal helical ridges and grooves, have a helix angle of 5 to 50 degrees, and wherein the helical flow inducing tubing comprises blood flow tubing.
2. A method according to claim 1 , wherein the tubing comprises a non-circular cross-section and twist.
3. A method according to claim 1 , wherein the internal helical ridges and/or grooving have a helical formation having a constant helix angle along at least part of its length.
4. A method according to claim 1 , wherein the internal helical ridges and/or grooving have an increasing or reducing helix angle over at least part of its length.
5. A method according to claim 1 , wherein the internal helical ridges and/or grooves have a helix angle of 5 to 16 degrees.
6. A method according to claim 1 , wherein the internal helical grooving and/or ridging tapers in the direction of flow and/or in the opposite direction.
7. A method according to claim 1 , wherein the tubing has an exterior surface and the cross-section of the exterior surface perpendicular to the longitudinal axis of the tubing is circular.
8. A method according to claim 1 , wherein the tubing has a branched structure in which the flow is from a first branch into two second branches, and wherein the helical ridges and/or grooving have a helix angle of 5 to 16 degrees, in such a fashion as to reduce or eliminate turbulence from the first branch.
9. A method as defined in claim 1 , wherein the at least two internal helical ridges, the at least two internal helical grooves, or the at least two internal helical ridges and at least two internal helical grooves extend spaced apart around the circumference of the tubing along a substantial longitudinal portion of the helical flow inducing tubing between a pair of first and second ends thereof.
10. A method of inducing helical flow within a tubing, comprising the steps of:
providing helical flow inducing tubing comprising at least two internal helical ridges, at least two internal helical grooves, or at least two internal helical ridges and at least two internal helical grooves configured in such a fashion as to eliminate or reduce turbulence in the helical flow inducing tubing, the at least two internal helical ridges, the at least two internal helical grooves, or the at least two internal helical ridges and at least two internal helical grooves extending spaced apart along a substantial longitudinal portion of the helical flow inducing tubing, each of the at least two helical ridges, at least two internal helical grooves, or the at least two internal helical ridges and at least two internal helical grooves being located at a different point of the circumference of the tubing at each of one or more cross-sections taken on a plane normal to the longitudinal axis of the tubing wherein at least one of the internal helical ridges and the grooves, have a helix angle of 5 to 50 degree, and wherein the helical flow inducing tubing is blood flow tubing; and
inducing a helical flow of blood within the helical flow inducing tubing.