Impellers, blood pumps, and methods of treating a subject
One embodiment of the invention provides a variable pitch impeller for a blood pump. The variable pitch impeller includes: a flexible polymer defining a plurality of blades extending from a first end to a second end, the blades having a resting non-zero pitch; an external shaft coupled to a first end of the flexible polymer; and an internal shaft received within the external shaft and coupled to the second end of the flexible polymer. The internal shaft and the external shaft are rotatable with respect to each other to achieve a blade pitch between about 0.0001° and about 2,880°.
1. A variable pitch impeller for a blood pump, the variable pitch impeller comprising:
a flexible polymer defining a plurality of helical blades and helical flutes extending from a first end to a second end, the plurality of helical blades having a resting non-zero blade pitch;
an external shaft coupled to the first end of the flexible polymer; and
an internal shaft received within the external shaft and coupled to the second end of the flexible polymer;
wherein the internal shaft and the external shaft are rotatable with respect to each other to achieve a second blade pitch of the plurality of helical blades different from the resting non-zero blade pitch, the second blade pitch between about 0.0001° and about 2,880°.
2. The variable pitch impeller of claim 1 , wherein the plurality of helical blades consists of between 2 and 10 blades.
3. The variable pitch impeller of claim 1 , wherein the plurality of helical blades are arranged at uniform angles about the impeller.
4. The variable pitch impeller of claim 3 , further comprising:
one or more fixed blades.
5. The variable pitch impeller of claim 4 , wherein the one or more fixed blades are located at an opposite end of the impeller from the plurality of helical blades.
6. The variable pitch impeller of claim 1 , wherein the plurality of helical blades have a height between about 0.1 mm and about 15 mm.
7. The variable pitch impeller of claim 1 , wherein the impeller has an external diameter between about 3 mm and about 28 mm.
8. The variable pitch impeller of claim 1 , wherein the flexible polymer includes one or more polymers selected from the group consisting of: piezoelectric polymers and electroactive polymers.
9. The variable pitch impeller of claim 1 , wherein the flexible polymer includes biocompatible polyurethane.
10. The variable pitch impeller of claim 1 , wherein the flexible polymer is decouplable from the external shaft and the internal shaft.
11. The variable pitch impeller of claim 1 , wherein the variable pitch impeller is fabricated entirely from non-ferrous materials.
12. The variable pitch impeller of claim 1 , wherein the inner shaft is fabricated from a bronze alloy.
13. A blood pump comprising the variable pitch impeller as described in claim 1 .
14. A variable pitch impeller for a blood pump, the variable pitch impeller comprising:
a flexible polymer defining a plurality of helical blades and helical flutes extending from a first end to a second end;
an external shaft coupled to the first end of the flexible polymer; and
an internal shaft received within the external shaft and coupled to the second end of the flexible polymer;
wherein the internal shaft and the external shaft are rotatable with respect to each other to achieve a blade pitch per length of the plurality of helical blades of at least 2.8°/mm.
15. The variable pitch impeller of claim 14 , wherein the blade pitch per length of the plurality of helical blades is at least 8.0°/mm.
16. The variable pitch impeller of claim 14 , wherein the blade pitch per length of the plurality of helical blades is at least 11.0°/mm.