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. Helical flow inducing tubing comprising only one internal helical ridge having a helix angle in the range of 5-16 degrees, wherein the tubing is adapted to induce helical flow in such a fashion as to reduce turbulence in the tubing.
2. The tubing of claim 1 , wherein the tubing comprises a non-circular cross-section and a twist.
3. The tubing of claim 2 , wherein the tubing is comprised of a synthetic or thermoplastic material, the tubing being plastified and reset in a twisted condition.
4. The tubing of claim 1 wherein the helical ridge has a constant helix angle along at least a part of its length.
5. The tubing of claim 1 wherein the helical ridge has a reducing or increasing helix angle over at least part of its length.
6. The tubing of claim 1 , wherein the helical ridge has a helix angle of 16 degrees.
7. The tubing of claim 1 wherein the internal helical ridge is tapered in the direction of flow.
8. The tubing of claim 1 , wherein the tubing comprises a bio-compatible insert.
9. The tubing according to claim 8 , wherein the bio-compatible insert comprises a helical vane portion, the vane portion being in the form of a fan blade, propeller blades, or which comprise an elongated spiral projections extending from the inner surface of a cylindrical insert.
10. The tubing according to claim 1 , wherein the tubing is an artificial natural blood flow tubing.
11. A blood flow tubing comprising internal helical flow inducing means, the tubing having a branched structure in which the flow is from a first branch into two second branches, wherein the helical flow inducing means eliminates turbulence from the first branch and comprises only one internal helical ridge having a helix angle in the range of 5-16 degrees.
12. The tubing of claim 1 , wherein the tubing comprises a vascular prosthesis.
13. The tubing of 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.