Adjustable shunts and associated systems and methods
The present technology is directed to adjustable interatrial shunting systems that selectively control blood flow between the left atrium and the right atrium of a patient. The adjustable interatrial devices include a shunting element having an outer surface configured to engage native tissue and an inner surface defining a lumen that enables blood to flow from the left atrium to the right atrium when the system is deployed across the septal wall. The systems can include an actuation assembly for selectively adjusting a geometry of the lumen and/or a geometry of a lumen orifice to control the flow of blood through the lumen.
1. An adjustable shunt assembly, comprising:
a self-expanding shunting element configured to extend through a tissue wall between a first body region of a patient and a second body region of the patient, wherein the shunting element comprises an artificial lumen through the tissue wall to shunt fluid between the first body region and the second body region of the patient; and
a shape memory actuation element coupled to the shunting element and configured to adjust a geometry of the artificial lumen, wherein the shape memory actuation element is mechanically expandable at body temperature and thermally contractible when heated above a transition temperature greater than the body temperature,
wherein the shunt assembly is configured such that expanding the shape memory actuation element increases a dimension of the artificial lumen and contracting the shape memory actuation element decreases the dimension of the artificial lumen.
2. The adjustable shunt assembly of claim 1 wherein the transition temperature is at least about 45 degrees Celsius.
3. The adjustable shunt assembly of claim 1 wherein, at body temperature, the shape memory actuation element is configured to be mechanically expanded by an inflatable balloon.
4. The adjustable shunt assembly of claim 1 wherein the shape memory actuation element is configured to be heated above the transition temperature using an energy source delivered via a catheter.
5. The adjustable shunt assembly of claim 1 wherein the shape memory actuation element is configured to be resistively heated above the transition temperature.
6. The adjustable shunt assembly of claim 1 wherein the shape memory actuation element is composed, at least in part, of nitinol and/or a nitinol-based alloy.
7. The adjustable shunt assembly of claim 1 wherein the shape memory actuation element is in a martensitic material state or an R-phase material state at body temperature, and wherein the shape memory actuation element is configured to transition to an R-phase material state or an austenitic material state when heated above the transition temperature.
8. The adjustable shunt assembly of claim 1 wherein the artificial lumen is at least partially defined by the shape memory actuation element.
9. The adjustable shunt assembly of claim 1 wherein the artificial lumen includes an orifice, and wherein (a) increasing a dimension of the artificial lumen includes increasing a diameter of the orifice, and (b) decreasing a dimension of the artificial lumen includes decreasing the diameter of the orifice.
10. The adjustable shunt assembly of claim 1 wherein the tissue wall is a septal wall, the first body region is a left atrium of the patient's heart, the second body region is a right atrium of the patient's heart, and the adjustable shunt assembly is configured to shunt blood from the left atrium to the right atrium.
11. An adjustable shunt assembly, comprising:
a shunting element having a lumen extending therethrough and configured to extend through a septal wall between left atrium of a patient and a right atrium of the patient to shunt fluid therebetween;
a right atrium element and/or left atrium element configured to stabilize the shunting element across the septal wall; and
a shape memory actuation element carried by the shunting element, wherein the shape memory actuation element is transitionable between a first material state and a second material state by heating the shape memory actuation element above a transition temperature greater than body temperature, and wherein—
in the first material state, the shape memory actuation element is configured to be mechanically deformed relative to its manufactured geometry to alter a dimension of the lumen; and
the shape memory actuation element is configured such that heating the shape memory actuation element above the transition temperature causes the shape memory actuation element to transition to the second material state and, if the shape memory actuation element is deformed relative to the manufactured geometry, move to and/or toward the manufactured geometry.
12. The adjustable shunt assembly of claim 11 wherein the transition temperature is at least about 45 degrees Celsius.
13. The adjustable shunt assembly of claim 11 wherein the shape memory actuation element comprises nitinol and/or nitinol alloys.
14. The adjustable shunt assembly of claim 11 wherein the first material state is a martensitic material state or an R-phase material state, and wherein the second material state is an R-phase material state or an austenitic material state.
15. The adjustable shunt assembly of claim 11 wherein shape memory actuation element is configured to (a) be mechanically expanded away from the manufactured geometry when in the first material state to increase a dimension of the lumen, and (b) be thermally contracted toward the manufactured geometry when heated above the transition temperature to decrease a dimension of the lumen.
16. The adjustable shunt assembly of claim 11 wherein the shape memory actuation element is configured to be heated using an energy source delivered via a catheter.
17. The adjustable shunt assembly of claim 11 wherein the shape memory actuation element is configured to be resistively heated.
18. The adjustable shunt assembly of claim 11 wherein the shape memory actuation element at least partially defines the lumen.
19. A method of adjusting flow through a shunting assembly implanted in a septal wall of a heart of a patient, the shunting assembly having a shape memory actuation element and defining an artificial lumen through the septal wall fluidly connecting a left atrium of the patient and a right atrium of the patient, the method comprising:
decreasing a cross-sectional dimension of the lumen by heating the shape memory actuation element above a transition temperature to cause the shape memory actuation element to transition from a first material state to a second material state,
wherein transitioning from the first material state to the second material state induces a geometric change in the shape memory actuation element and reduces the cross-sectional dimension of the lumen; and
increasing the cross-sectional dimension of the lumen by mechanically deforming the shape memory actuation element.
20. The method of claim 19 wherein the transition temperature is greater than body temperature.
21. The method of claim 19 wherein the transition temperature is at least about 45 degrees Celsius.
22. The method of claim 19 wherein mechanically deforming the shape memory actuation element includes:
positioning a balloon within the shape memory actuation element; and
inflating the balloon.
23. The method of claim 19 wherein heating the shape memory actuation element includes delivering energy to the shape memory actuation element via a catheter.
24. The method of claim 19 wherein heating the shape memory actuation element includes resistively heating the shape memory actuation element.
25. The method of claim 19 wherein the shape memory actuation element is composed at least partially of nitinol and/or nitinol alloys.
26. The method of claim 19 wherein the first material state is a martensitic material state or an R-phase material state, and wherein the second material state is an R-phase material state or an austenitic material state.
27. The method of claim 19 wherein the increasing step is done after the decreasing step.
28. An interatrial shunt for adjustably regulating fluid flow in a heart having a first atrium, a second atrium, and an atrial septum, the interatrial shunt comprising:
a shunting element comprising a self-expanding material configured to be placed across the atrial septum to provide fluid flow from the first atrium to the second atrium,
the shunting element being self-expanding at body temperature; and
a shape memory actuation element coupled to the shunting element, the shape memory actuation element being malleable at body temperature, wherein—the malleable shape memory actuation element has a first dimension,
the malleable shape memory actuation element is expandable from the first dimension to a second dimension, and
the malleable shape memory actuation element is contractible from the second dimension to a third dimension.
29. The interatrial shunt of claim 28 wherein the malleable shape memory actuation element is mechanically expandable and thermally contractible.
30. The interatrial shunt of claim 28 wherein the shape memory actuation element is configured to be placed in the first atrium or the second atrium.