Expandable blood pumps and methods of their deployment and use

1. A pump for inducing flow within a vascular system, the pump comprising:

a cannula having at least one section adjustable between an operable configuration and a deployment configuration having a substantially smaller diameter than the operable configuration; and

an impeller positioned within the adjustable section of the cannula and rotatable therein about an impeller axis, the impeller comprising a flexible web suspended by or between one or more moveable support members, the one or more support members being positionable with respect to the cannula between the operable configuration and the deployment configuration by changing a position of the one or more support members, the operable configuration extending at least a portion of the web to a first radial distance from the impeller axis and the deployment configuration collapsing the portion of the web to a second substantially smaller radial distance from the impeller axis.

2. The pump of claim 1 , wherein the cannula comprises a spiral support member, the spiral support member spiraling about the impeller axis.

3. The pump of claim 2 , wherein the spiral support member is adjustable from the operable configuration to the deployment configuration by twisting.

4. The pump of claim 2 , wherein the spiral support member is adjustable from the operable configuration to the deployment configuration by axial positioning proximal and distal ends of the cannula with respect to one another.

5. The pump of claim 1 , wherein the cannula comprises a cover supported by a support structure.

6. The pump of claim 5 , wherein the cover comprises a plurality of inlet openings for flow into the cannula substantially perpendicular to the impeller axis.

7. The pump of claim 5 , wherein the cover comprises an outlet opening for flow to exit the cannula substantially perpendicularly to the impeller axis.

8. The pump of claim 1 , wherein the cannula comprises proximal and distal sections having substantially different diameters in the operable configuration.

9. The pump of claim 1 , wherein the cannula comprises a port fixation neck between proximal and distal sections.

10. The pump of claim 1 , wherein:

the one or more support members comprises first and second masts supporting the flexible web, the masts in the operable configuration being substantially perpendicular to the impeller axis and in the deployment configuration being substantially parallel to the impeller axis; and

the pump further comprises a catheter having a distal catheter section supporting the first mast and a proximal catheter section supporting the second mast, the distal and proximal catheter sections rotatable with respect to one other so as to radially offset the first and second masts.

11. The pump of claim 1 , further comprising a catheter having proximal and distal portions coupled to proximal and distal ends of the one or more support members, the catheter sections being axially positionable with respect to one another to position the web between the operable and deployment positions.

12. The pump of claim 11 , wherein the catheter sections are rotatable with respect to one another so as to radially offset the proximal and distal ends of the support members.

13. The pump of claim 1 , further comprising a drive shaft for rotating the impeller, the drive shaft comprising a proximal section having a first gear and a distal section having a second gear for transferring rotational motion to the impeller by adjacent positioning of the first and second gears.

14. The pump of claim 1 , further comprising a power transmission system for driving rotational motion of the impeller, the power transmission system comprising:

a mechanical generator coupled to the impeller for transferring fluid motion into rotational motion about the impeller axis; and

first and second lumens for driving the fluid motion through the mechanical generator.

15. The pump of claim 1 , further comprising a magnetic coupler for rotating the impeller about the axis, the magnetic coupler comprising:

a first magnet housing rotationally coupled to a mechanical generator; and

a second magnet housing rotationally coupled to the impeller, the second magnet housing positionable adjacent the first magnet housing to transfer rotational motion from the mechanical generator to the impeller.

16. A method comprising:

inserting a cannula into a vascular system, the cannula adjustable between an operable configuration and a deployment configuration having a substantially smaller diameter than the operable configuration;

guiding the cannula to a desired location within the vascular system;

expanding the cannula from the deployment configuration to the operable configuration;

expanding an impeller positioned along an axis within the cannula from a collapsed configuration to an expanded configuration by changing a position of one or more support members of the impeller, the impeller having a blade comprising a flexible web suspended by or between the one or more moveable support members, the blade extending to a greater radial distance from the axis in the expanded configuration than in the collapsed configuration.

17. The method of claim 16 , further comprising rotating the impeller about the axis to drive fluid through the vascular system.

18. The method of claim 16 , further comprising adjusting the impeller to a desired blade angle.

19. The method of claim 16 , further comprising collapsing the impeller from the expanded configuration to the collapsed configuration and adjusting the cannula from the operable configuration to the deployment configuration.

20. The method of claim 19 , further comprising removing the cannula and the impeller from the vascular system.