Hydraulically actuated cardiac prosthesis and method of actuation

Claim 2

An implantable hydraulic actuation system for supplying motive power to a blood pumping chamber having a flexible portion comprising: an actuation fluid reservoir; actuation fluid pumping means in fluid communication with said reservoir for providing intermittent pulses of actuation fluid; an actuation chamber having an actuation fluid inlet path in fluid communication with said pumping means, and a separate actuation fluid outlet path in fluid communication with said reservoir; said actuation chamber being adapted to cause displacement of the flexible portion of said blood pumping chamber in response to changes in volume of actuation fluid in said actuation chamber; and valve means associated with said actuation chamber adapted to close or open said actuation fluid outlet path primarily in response to forces which vary as a function of actuation fluid flow through said actuation fluid inlet path.

Claim 3

An implantable hydraulically actuated blood pumping system comprising: a blood pumping chamber having a blood inlet, a blood outlet and a flexible portion; an actuation fluid reservoir; actuation fluid pumping means in fluid communication with said reservoir for providing intermittent pulses of actuation fluid; an actuation chamber having an actuation fluid inlet path in fluid communication with said pumping means, and a separate actuation fluid outlet path in fluid communication with said reservoir, said actuation chamber being operatively associated with said blood pumping chamber to cause displacement of said flexible portion of said blood pumping chamber in response to changes in volume of actuation fluid in said actuation chamber; and valve means associated with said actuation chamber adapted to close or open said actuation fluid outlet path primarily in response to forces which vary as a function of actuation fluid flow through said actuation fluid inlet path whereby said actuation chamber fills with actuation fluid and blood is expelled from said associated blood pumping chamber while said valve means is closed, and actuation fluid drains from said actuation chamber and said associated blood pumping chamber is allowed to fill with blood while said valve means is open.

Claim 4

An implantable hydraulically actuated blood pumping system comprising: a blood pumping chamber having a blood inlet, a blood outlet and a flexible portion; an actuation fluid reservoir; actuation fluid pumping means in fluid communication with said reservoir for providing intermittent pulses of actuation fluid; an actuation chamber having an actuation fluid inlet path in fluid communication with said pumping means, and a separate actuation fluid outlet path in fluid communication with said reservoir, said actuation chamber being operatively associated with said blood pumping chamber to cause displacement of said flexible portion of said blood pumping chamber in response to changes in volume of actuation fluid in said actuation chamber; and valve means associated with said actuation chamber adapted to close or open said actuation fluid outlet path primarily in response to forces which vary as a function of actuation fluid flow through said actuation fluid inlet path whereby said actuation chamber fills with actuation fluid and blood is expelled from said associated blood pumping chamber while said valve means is closed, and actuation fluid drains from said actuation chamber and said associated blood pumping chamber is allowed to fill with blood while said valve means is open.

Claim 5

An implantable hydraulically actuated total cardiac prosthesis comprising: a pair of blood pumping chambers each having a blood inlet, a blood outlet and a flexible portion; a pair of actuation chambers each having an actuation fluid inlet path and a separate actuation fluid outlet path, one of said actuation chambers being operatively associated with one of said blood pumping chambers and the other of said actuation chambers being operatively associated with the other of said blood pumping chambers to cause displacement of the flexible portion of said blood pumping chambers in response to changes in volume of actuation fluid in their associated actuation chambers; an actuation fluid reservoir in fluid communication with said actuation fluid outlet paths; actuation fluid pumping means in fluid communication with said reservoir and said actuation fluid inlet paths for providing intermittent pulses of actuation fluid from said reservoir to said actuation chambers; and valve means associated with said actuation chambers adapted to close or open said actuation fluid outlet path primarily in response to forces which vary as a function of actuation fluid flow through said associated actuation fluid inlet path whereby said actuation chamber fills with actuation fluid and blood is expelled from said associated blood pumping chamber while said valve means is closed, and actuation fluid drains from said actuation chamber and said associated blood pumping chamber is allowed to fill with blood while said valve means is open.

Claim 6

An implantable hydraulically actuated total cardiac prosthesis comprising: a pair of blood pumping chambers each having a blood inlet, a blood outlet and a flexible portion; a pair of actuation chambers each having an actuation fluid inlet path and a separate actuation fluid outlet path, one of said actuation chambers being operatively associated with one of said blood pumping chambers and the other of said actuation chambers being operatively associated with the other of said blood pumping chambers to cause displacement of the flexible portion of said blood pumping chambers in response to changes in volume of actuation fluid in their associated actuation chambers; an actuation fluid reservoir in fluid communication with said actuation fluid outlet paths; actuation fluid pumping means in fluid communication with said reservoir and said actuation fluid inlet paths for providing intermittent pulses of actuation fluid from said reservoir to said actuation chambers; and valve means associated with said actuation chambers adapted to close or open said actuation fluid outlet path primarily in response to forces which vary as a function of actuation fluid flow through said associated actuation fluid inlet path whereby said actuation chamber fills with actuation fluid and blood is expelled from said associated blood pumping chamber while said valve means is closed, and actuation fluid drains from said actuation chamber and said associated blood pumping chamber is allowed to fill with blood while said valve means is open.

Claim 7

The invention of claims 1, 2 or 3 wherein said actuation fluid reservoir comprises a compliant zone defined at least in part by a flexible wall portion made from biocompatible elastomeric material.

Claim 8

The invention of claim 4 wherein said actuation fluid reservoir also includes flexible ducting leading to and from said actuation fluid pumping means and to and from said actuation chamber.

Claim 9

The invention of claim 3 wherein said actuation fluid reservoir comprises a separate compliant zone associated with each of said actuation chambers, defined at least in part by a flexible wall portion made from biocompatible elastomeric material, said compliant zones communicating with each other, said pumping means and said actuation chambers by flexible ducting.

Claim 10

The invention of claims 1 or 2 wherein said actuation fluid pumping means comprises a pump and drive motor therefor.

Claim 11

The invention of claim 7 wherein said pump is a high speed, mixed flow rotary pump.

Claim 12

The invention of claim 7 wherein said drive motor is a brushless DC electric motor.

Claim 13

The invention of claim 9 further comprising means for commutating said brushless DC electric motor.

Claim 14

The invention of claim 10 wherein said means for commutating comprises back-emf control circuitry.

Claim 15

The invention of claim 3 wherein said actuation fluid pumping means comprises a separate pump and drive motor therefor associated with each of said actuation chambers.

Claim 16

The invention of claim 12 wherein each of said pumps is a high speed, mixed flow rotary pump.

Claim 17

The invention of claim 12 wherein each of said drive motors is a brushless DC electric motor.

Claim 18

The invention of claim 14 further comprising means for commutating said brushless DC electric motor.

Claim 19

The invention of claim 15 wherein said means for commutating comprises back-emf control circuitry.

Claim 20

The invention of claim 3 wherein said actuation fluid pumping means comprises a pump and drive motor therefor and a three-way switching valve associated with the pump outlet for alternately directing the pump output to one or the other of said actuation chambers.

Claim 21

The invention of claim 17 wherein said pump is a high speed, mixed flow rotary pump.

Claim 22

The invention of claim 17 wherein said drive motor is a brushless DC electric motor.

Claim 23

The invention of claim 19 further comprising means for commutating said brushless DC electric motor.

Claim 24

The invention of claim 20 wherein said means for commutating comprises back-emf control circuitry.

Claim 25

The invention of claim 17 wherein said three-way switching valve has a separate drive motor associated therewith.

Claim 26

The invention of claims 2 or 3 wherein said blood inlet and said blood outlet are provided with prosthetic valves adapted to permit the flow of blood in only one direction.

Claim 27

The invention of claims 2 or 3 wherein said blood pumping chamber comprises a variable volume zone defined in part by a flexible membrane made from biocompatible elastomeric material and in part by a rigid blood pumping chamber housing.

Claim 28

The invention of claims 1, 2 or 3 wherein said actuation chamber comprises a variable volume zone defined in part by said flexible portion of said blood pumping chamber and in part by a rigid actuation chamber housing.

Claim 29

The invention of claims 1, 2 or 3 wherein said valve means is adapted: to close said actuation fluid outlet path at the beginning of each of said fluid pulses when sufficient flow of actuation fluid is supplied to said actuation fluid inlet path to create forces above a predetermined threshold magnitude; to keep said actuation fluid outlet path closed during said pulses while said flow through said inlet path is sufficient to maintain said forces above said predetermined threshold magnitude; and to open said actuation fluid outlet path at the end of said pulses when said flow through said inlet path is reduced to a value at which said forces fall below said predetermined threshold magnitude.

Claim 30

The invention of claim 26 wherein said valve means includes means for exerting a permanent bias force tending to open said actuation fluid outlet path, and the magnitude of said bias force is equal to said predetermined threshold.

Claim 31

The invention of claim 27 wherein said valve means is adapted to act in response to pressure forces created by the flow of actuation fluid through said inlet path.

Claim 32

The invention of claim 28 wherein said valve means comprises a hollow closure member having an interior in fluid communication with actuation fluid delivered by said pumping means, and movable between a closed position blocking said actuation fluid outlet path when filled with actuation fluid during fluid pulses, and an open position clear of said actuation fluid outlet path between fluid pulses.

Claim 33

The invention of claim 29 wherein said closure member comprises an expandable envelope.

Claim 34

The invention of claim 30 wherein said envelope comprises elastomeric material.

Claim 35

The invention of claim 27 wherein said valve means comprises a closure member in said fluid inlet path and movable between a closed position blocking said fluid outlet path during fluid pulses, and an open position clear of said actuation fluid outlet between fluid pulses.

Claim 36

The invention of claim 32 wherein said valve means is adapted to act in response to differential pressure forces.

Claim 37

The invention of claim 33 wherein said fluid inlet path includes at least one orifice through said closure member through which actuation fluid flows from said pumping means into said actuation chamber.

Claim 38

The invention of claim 34 wherein said closure member is hollow and has an interior in fluid communication with actuation fluid delivered by said pumping means, and said orifice is formed through the wall of said hollow closure member.

Claim 39

The invention of claim 35 wherein said closure member comprises an expandable envelope.

Claim 40

The invention of claim 36 wherein said orifice is formed through a substantially rigid wall portion of said envelope.

Claim 41

The invention of claim 37 wherein said envelope comprises elastomeric material.

Claim 42

The invention of claim 36 wherein said envelope comprises elastomeric material.

Claim 43

The invention of claim 34 further comprising means for maintaining a substantially constant pressure differential across said closure member during fluid pulses despite changes in flow rate of fluid along said fluid inlet path.

Claim 44

The invention of claim 40 wherein said means for maintaining a substantially constant pressure differential comprises at least one aperture through said closure member, and shutter means biased to substantially close said aperture, but movable to open said aperture to an extent proportional to the flow rate of fluid along said fluid inlet path.

Claim 45

The invention of claim 41 wherein said shutter means comprises a leaf spring shutter overlying said aperture.

Claim 46

The invention of claim 41 wherein said closure member is hollow and has an interior in fluid communication with actuation fluid delivered by said pumping means, and said orifice and said aperture are formed through the wall of said hollow closure member.

Claim 47

The invention of claim 43 wherein said closure member comprises an expandable envelope.

Claim 48

The invention of claim 44 wherein said orifice and said aperture are formed through a substantially rigid wall portion of said envelope.

Claim 49

The invention of claim 45 wherein said envelope comprises elastomeric material.

Claim 50

The invention of claim 44 wherein said envelope comprises of elastomeric material.

Claim 51

The invention of claim 2 or 3 further comprising means for applying electric power to said actuation fluid pumping means and associated control electronics in a patient having an implanted cardiac prosthesis.

Claim 52

The invention of claim 48 wherein said means for supplying electric power comprises an external primary coil inductively coupled to a subcutaneous secondary coil for transmitting electrical energy across the intact skin of said patient.

Claim 59

The method of claim 52 wherein said total cardiac prosthesis is operated in an alternately pulsatile fashion by alternate intermittent pulses of actuation fluid to first one and then the other of said actuation chambers.

Claim 60

The method of claim 52 wherein said total cardiac prosthesis is operated in copulsatile fashion by supplying intermittent pulses of actuation fluid to both of said actuation chambers at substantially the same time.

Claim 62

The method of claim 55 wherein said pressure forces are differential pressure forces.