Cardiac assist device with high frequency operation
A cardiac assist device with an expandable cup ( 4 ) having a transport state and an operational state, the expandable cup comprising a plurality of inflow apertures ( 5 ), and an outflow nozzle ( 6 ), and an inflatable balloon ( 8 ) positioned inside the expandable cup ( 4 ). A catheter assembly ( 3 ) is connected to the inflatable balloon ( 8 ) during operation, and a control unit ( 2 ) is connected to the catheter assembly ( 3 ). The control unit ( 2 ) is arranged to operate the inflatable balloon ( 8 ) with a frequency of more than 100 beats per minute.
1. A heart assist device comprising:
a flexible catheter shaft having a proximal end and a distal end;
an expandable and collapsible cup coupled to the distal end of the catheter shaft and having a pumping chamber;
an inflow section and an outflow section each being in communication with the pumping chamber, wherein the inflow section has an inlet and the outflow section has an outlet, wherein the inflow and outflow sections each has a size and a shape such that when the inlet is in a heart chamber upstream of a heart valve, the outlet is positioned in a vascular lumen downstream of the heart valve;
a one-way valve configured to open to allow blood flow through the inlet into the pumping chamber and further configured to close to block blood flow through the inlet out of the pumping chamber; and
a pumping mechanism in the cup configured to operate cyclically between an inflow phase and an ejection phase to displace blood from the pumping chamber through the outlet, wherein the one-way valve is open during the inflow phase and closed during at least a first portion of the ejection phase, and wherein during a second portion of the ejection phase blood is drawn through the inlet into the pumping chamber while blood exits the pumping chamber;
wherein the pumping mechanism is configured to operate cyclically between the inflow phase and the ejection phase at a frequency of at least 100 cycles per minute.
2. The heart assist device of claim 1 , wherein the cup comprises a support structure embedded in or covered by a membrane.
3. The heart assist device of claim 2 , wherein the support structure extends along at least a portion of the outflow section.
4. The heart assist device of claim 2 , wherein the support structure comprises a metal mesh or scaffold.
5. The heart assist device of claim 1 , wherein the cup is configured for placement in a left ventricle of a heart, and the outflow section is configured to be at least partially disposed in an aortic lumen downstream of an aortic valve when the cup is in the left ventricle.
6. The heart assist device of claim 1 , wherein the pumping mechanism comprises an expandable member movable between an expanded configuration and a collapsed configuration.
7. The heart assist device of claim 6 , wherein the expandable member comprises an inflatable balloon.
8. The heart assist device of claim 7 , wherein the inflatable balloon is spaced apart from an inner wall of the pumping chamber when fully inflated.
9. The heart assist device of claim 1 , wherein the one-way valve is fixed to the cup or the inflow section.
10. The heart assist device of claim 1 , wherein the inflow section comprises a portion of the cup and the inlet comprises an opening or aperture in the cup.
11. The heart assist device of claim 1 , further comprising an outflow valve in the outflow section configured to close during the inflow phase and open during the ejection phase.
12. The heart assist device of claim 1 , wherein the pumping mechanism is configured to operate at a frequency of at least 600 cycles per minute.
13. The heart assist device of claim 1 , wherein the pumping mechanism is configured to operate at a frequency sufficient to pump blood at a rate of at least 5 liters/minute.
14. The heart assist device of claim 1 , wherein a volume V d of blood is displaced from the pumping chamber during each ejection phase, and the pumping mechanism is configured to increase the velocity of the blood such that the flow rate of blood exiting the pumping chamber exceeds the product of the frequency times the volume V d .
15. The heart assist device of claim 14 , wherein the flow rate is at least 40% higher than the product of the frequency times the volume V d .
16. The heart assist device of claim 14 , wherein the pumping mechanism increases the velocity of the blood exiting the pumping chamber so as to drag along blood in its wake.
17. The heart assist device of claim 14 , wherein the cup or the outlet section is configured to create a venturi effect in the blood exiting the pumping chamber.
18. The heart assist device of claim 1 , wherein at least one of the pumping chamber, the pumping mechanism, or the outflow section is configured to accelerate blood exiting the pumping chamber so as to draw blood into the pumping chamber through the inlet during the second portion of the ejection phase.
19. A heart assist device comprising:
a flexible catheter shaft having a proximal end and a distal end;
an expandable and collapsible cup coupled to the distal end of the catheter shaft and having a pumping chamber, the cup being sized and shaped such that at least a portion of the cup is configured for placement in a left ventricle of a heart;
an inflow section and an outflow section each being in communication with the pumping chamber, wherein the inflow section has an inlet and the outflow section has an outlet, wherein the inflow and outflow sections each has a size and a shape such that when the inlet is positioned in the left ventricle, the outlet is positioned in a vascular lumen downstream of an aortic valve;
a one-way valve coupled to the cup and configured to open to allow blood flow into the pumping chamber through the inflow section and further configured to close to block blood flow out of the pumping chamber through the inflow section; and
a pumping mechanism within the pumping chamber configured to operate cyclically between an inflow phase in which blood flows into the pumping chamber through the inlet and an ejection phase in which blood flows out of the pumping chamber through the outlet, wherein the one-way valve is open during the inflow phase and closed during at least a first portion of the ejection phase, and wherein during a second portion of the ejection phase blood is drawn through the inlet into the pumping chamber while blood exits the pumping chamber;
wherein the pumping mechanism is configured to operate cyclically between the inflow phase and the ejection phase at a frequency of at least 100 cycles per minute.
20. The heart assist device of claim 19 , wherein the cup comprises a support structure embedded in or covered by a membrane.
21. The heart assist device of claim 20 , wherein the outflow section comprises an extension of the membrane and the support structure.
22. The heart assist device of claim 20 , wherein the support structure comprises a metal mesh or scaffold.
23. The heart assist device of claim 19 , wherein the pumping mechanism comprises an expandable member movable between an expanded configuration and a collapsed configuration.
24. The heart assist device of claim 23 , wherein the expandable member comprises an inflatable balloon.
25. The heart assist device of claim 19 , wherein the one-way valve is fixed to the cup.
26. The heart assist device of claim 19 , wherein the pumping mechanism is configured to operate at a frequency of at least 600 cycles per minute.
27. The heart assist device of claim 19 , wherein a volume V d of blood is displaced from the pumping chamber during each ejection phase, and the pumping mechanism is configured to increase the velocity of the blood such that the flow rate of blood exiting the pumping chamber exceeds the product of the frequency times the volume V d .