Purge-free miniature rotary pump

1. A paracardial blood pump, comprising:

a distal end configured as a blood flow inlet;

a proximal end configured as a blood flow outlet;

a tubular housing with a longitudinal axis,

a drive unit arranged coaxially within the tubular housing, the drive unit comprising a rotor motor magnet and a stator motor magnet, the rotor motor magnet and the stator motor magnet configured to drive a rotation of an impeller positioned at one end of the drive unit;

a longitudinally extending primary flow channel positioned between an interior wall of the housing and an exterior of the drive unit;

a pump ring with an axial inlet positioned at one end of the tubular housing and surrounding at least a portion of the impeller, wherein the drive unit drives a rotation of the impeller within the pump ring;

a cannula extending from an end of the tubular housing nearest the impeller;

a laterally branching outlet tube positioned proximate an end of the tubular housing opposite the impeller, the laterally branching outlet tube positioned perpendicularly to the primary flow channel;

a secondary flow channel formed between the rotor motor magnet and the stator motor magnet, the secondary flow channel configured to direct a flow of blood in a direction generally opposite a direction of blood flow through the primary flow channel wherein the primary flow channel and the secondary flow channel are in fluid communication with each other

such that blood flows from the primary flow channel to the secondary flow channel in a direction perpendicular to the longitudinal axis and positioned proximally of the laterally branching outlet tube.

2. The paracardial blood pump of claim 1 , further comprising a first radial magnetic bearing positioned in the drive unit near the impeller and a second radial magnetic bearing positioned towards an end of the drive unit opposite the impeller.

3. The paracardial blood pump of claim 2 , wherein the secondary flow channel extends through the first radial magnetic bearing and the second radial magnetic bearing, the axial hydraulic bearing configured to arrest distal translation of the rotor motor magnet.

4. The paracardial blood pump of claim 1 , further comprising an axial hydraulic bearing proximate the end of the drive unit nearest the impeller, the axial hydraulic bearing configured to arrest distal translation of the rotor motor magnet.

5. The paracardial blood pump of claim 4 , wherein the axial hydraulic bearing comprises openings adapted to allow blood to flow from the secondary flow channel through the bearing and into the primary flow channel.

6. The paracardial blood pump of claim 1 , further comprising an axial magnetic bearing proximate the end of the drive unit opposite the impeller.

7. The paracardial blood pump of claim 6 , wherein the axial magnetic bearing is at least partially active.

8. A paracardial blood pump, comprising:

a distal end configured as a blood flow inlet;

a proximal end configured as a blood flow outlet;

a drive unit arranged coaxially within a tubular housing, the drive unit comprising a rotor motor magnet and a stator motor magnet, the rotor motor magnet and the stator motor magnet configured to drive a rotation of an impeller positioned at one end of the drive unit;

a longitudinally extending primary flow channel between an exterior of the drive unit and an interior wall of the tubular housing, and a secondary flow channel is formed between the rotor motor magnet and the stator motor magnet, the secondary flow channel configured to direct a flow of blood between the rotor and the stator in a direction generally opposite a direction of blood flow through the primary flow channel;

a cannula extending from an end of the tubular housing nearest the impeller, the impeller configured to convey blood through the cannula to the primary flow channel;

a laterally branching outlet tube positioned proximate an end of the tubular housing opposite the impeller, the laterally branching outlet tube positioned perpendicularly to the primary flow channel; and

wherein the secondary flow channel and the primary flow channel are in fluid communication such that blood flows from the secondary flow channel to the primary flow channel the blood flowing perpendicularly to a longitudinal axis of the tubular housing and proximally of the laterally branching outlet tube.

9. The paracardial blood pump of claim 8 , wherein the tubular housing comprises a blood inlet at a distal portion of the tubular housing, wherein the impeller is configured to convey blood into the tubular housing and through the tubular housing in a proximal direction.

10. The paracardial blood pump of claim 9 , further comprising a pump ring with an axial inlet positioned at one end of the tubular housing and surrounding at least a portion of the impeller, wherein the primary flow channel extends through the axial inlet.

11. The paracardial blood pump of claim 10 , wherein the pump ring comprises a blood outlet, wherein the impeller is configured to convey blood through the tubular housing and out of the paracardial blood pump through the blood outlet.

12. The paracardial blood pump of claim 8 , further comprising a first radial magnetic bearing positioned in the drive unit near the impeller and a second radial magnetic bearing positioned towards an end of the drive unit opposite the impeller.

13. The paracardial blood pump of claim 8 , further comprising an axial hydraulic bearing proximate the end of the drive unit nearest the impeller, the axial hydraulic bearing configured to arrest distal translation of the rotor.

14. The paracardial blood pump of claim 13 , wherein the axial hydraulic bearing comprises openings adapted to allow blood to flow the secondary flow channel through the bearing and into the primary flow channel.

15. The paracardial blood pump of claim 8 , further comprising an axial magnetic bearing proximate the end of the drive unit opposite the impeller.

16. The paracardial blood pump of claim 15 , wherein the axial magnetic bearing is at least partially active.