Left ventricular cardiac assist pump and methods therefor
A left ventricular cardiac assist pump includes an inlet opening and a discharge opening aligned in an axial direction. The pump includes a casing spaced from a stator and impeller, with at least one connecting spacer connecting the casing and the stator. The impeller is configured to direct the blood towards the casing and the discharge opening, so that blood flows through the pump principally between the casing and the rotor-stator assembly.
1. A left ventricular cardiac assist pump having an inlet opening and a discharge opening aligned along an axial direction of the pump, the pump comprising:
a rotor comprising an impeller and a shaft provided with electric motor magnets;
a stator arranged around the shaft and provided with electric motor stator windings; and
a casing offset from the stator and radially spaced from the impeller and the stator thereby defining a radial gap therebetween, the rotor and the stator forming a rotor-stator assembly surrounded by the casing, with at least one connecting spacer connecting and offsetting the casing and the stator, the casing defining the inlet opening and the discharge opening of the pump,
the impeller being positioned on a side of the inlet opening and configured to circulate blood within the radial gap, towards the casing and towards the discharge opening, the radial gap extending along the impeller and the stator so as to not obstruct the flow of blood and whereby the blood flows through the pump substantially within the radial gap between the casing and the impeller and stator.
2. The pump of claim 1 , wherein the casing is made of a solid structure having substantial rigidity and each connecting spacer is made of a solid structure having substantial rigidity.
3. The pump of claim 2 , wherein the casing comprises a diverging portion, a straight portion and a converging portion, with the straight portion extending between the converging portion and the diverging portion, the diverging portion extending from an inlet extremity defining the inlet opening to the straight portion, and the converging portion extending from the straight portion to a discharge extremity defining the discharge opening.
4. The pump of claim 3 , wherein the impeller is positioned between the diverging portion and the straight portion of the casing.
5. The pump of claim 2 , wherein the casing comprises eyelets on an external portion thereof for holding wires.
6. The pump of claim 1 , wherein the rotor comprises an upstream head connected to the shaft, said upstream head having an annular top, with an upstream face on the side of the inlet opening and a downstream face on a side of the shaft, the upstream and downstream faces extending from the annular top, said upstream face forming said impeller.
7. The pump of claim 6 , wherein the upstream face of the upstream head forming the impeller comprises blades projecting from a surface having a diameter decreasing from the annular top to an upstream extremity of the rotor.
8. The pump of claim 6 , wherein the downstream face of the upstream head has a surface with a diameter decreasing from the annular top to the shaft, the stator having, on the side of the inlet opening, an upstream surface inclined similarly to the surface of the downstream face of the upstream head, with upstream electromagnetic bearing magnets being provided behind the surface of the downstream face of the upstream head and upstream electromagnetic bearing stator windings being provided behind the upstream surface of the stator.
9. The pump of claim 6 , wherein the rotor comprises a downstream head connected to the shaft on the side of the discharge opening, said downstream head having an annular top with an upstream face on the side of the shaft and a downstream face on the side of the discharge opening, the upstream and downstream faces extending from the annular top, the upstream face having a surface with a diameter decreasing from the annular top to the shaft, the stator having on the side of the discharge opening a downstream surface inclined similarly to the surface of the upstream face of the downstream head, with downstream electromagnetic bearing magnets being provided behind the surface of the upstream face of the downstream head and downstream electromagnetic bearing stator windings being provided behind the downstream surface of the stator.
10. The pump of claim 6 , wherein the upstream face of the upstream head has a surface with a diameter decreasing from the annular top to the upstream extremity of the rotor, the casing having a diverging portion in relation to the upstream face of the upstream head, with electromagnetic bearing magnets being provided behind the surface of the upstream face of the upstream head and electromagnetic bearing stator windings being provided behind an internal surface of the diverging portion of the casing.
11. The pump of claim 6 , wherein the upstream face of the upstream head has a surface with a diameter decreasing from the annular top to the upstream extremity of the rotor, said pump comprising a support element supporting the upstream extremity of the rotor and being connected to the casing by arms.
12. The pump of claim 1 , wherein the casing is made of a shape memory resilient material and the at least one connecting spacer is made of a shape memory resilient material.
13. The pump of claim 12 , wherein the rotor has a bore extending from an upstream extremity to a downstream extremity.
14. The pump of claim 1 , wherein the rotor-stator assembly is generally spindle-shaped.
15. The pump of claim 1 , further comprising an electrical cable running along the connecting spacer.
16. The pump of claim 1 , wherein the at least one connecting spacer is helical in shape and extends along the stator.
17. The pump of claim 1 , wherein the length of the pump is between 25 mm and 80 mm and a diameter of the pump is between 15 mm and 60 mm.
18. The pump of claim 1 , wherein the radial gap remains substantially constant throughout the pump.