Oval stent
A stent comprises an elastically deformable stent wall forming a lumen extending between a first opening and a second opening of the stent. The stent wall is configured to be percutaneously delivered into a blood vessel, secure to a blood vessel wall of a blood vessel, and radially expand from a first configuration to a second configuration within the blood vessel into direct contact with the blood vessel wall. The first configuration defines a first major dimension, a first minor dimension, a first cross-sectional area, a first cross-sectional shape, and a first perimeter of the stent wall. The second configuration defines a second major dimension, a second minor dimension that is greater than the first minor dimension, a second cross-sectional area that is greater than the first cross-sectional area, and the first perimeter of the stent wall.
1 . A stent comprising:
an elastically deformable stent frame lattice for increasing compliance and diastolic flow in a pulmonary artery, the stent frame lattice having a biased non-circular cross-sectional shape and being sized for placement in the pulmonary artery;
wherein the stent frame lattice is adapted to:
be percutaneously delivered into the pulmonary artery;
secure to a blood vessel wall of the pulmonary artery;
assume a biased first configuration characterized by a non-circular cross-sectional shape with inwardly-bowed minor-dimension sidewalls, a first major diameter, a first central minor diameter, and a first cross-sectional area;
upon deployment in the pulmonary artery, deform to a second configuration in response to diastolic pressure conditions, in which the stent frame lattice assumes an oval cross-sectional shape with outwardly-bowed minor-dimension sidewalls, a second major diameter, a second central minor diameter that is greater than the first central minor diameter, and a second cross-sectional area that is greater than the first cross-sectional area;
in response to systolic pressure conditions, transition to a third configuration in which the stent frame lattice assumes a third major diameter that is less than the second major diameter, a third central minor diameter that is greater than the second central minor diameter, and a third cross-sectional area that is greater than the second cross-sectional area; and
cycle between the second configuration and the third configuration within the pulmonary artery in response to cardiac cycling between diastolic and systolic phases.
2 . The stent of claim 1 , wherein the stent frame lattice comprises nitinol.
3 . The stent of claim 1 , further comprising one or more barbs extending radially outwardly from the stent frame lattice.
4 . The stent of claim 1 , wherein at least a portion of the stent frame lattice is adapted to be endothelialized into the blood vessel wall.
5 . The stent of claim 1 , wherein the stent frame lattice comprises a first stent layer and a second stent layer, wherein the first stent layer and the second stent layer comprise a single continuous layer of open-celled material, and the second stent layer is folded within the first stent layer such that the first stent layer comprises an outer layer of the stent frame lattice.
6 . The stent of claim 5 , wherein the stent frame lattice comprises a third stent layer, wherein the first stent layer and the second stent layer and the third stent layer comprise a single continuous layer of open-celled material, and the third stent layer is folded within the second stent layer such the third stent layer comprises an inner layer and the second stent layer is positioned between the first stent layer and the third stent layer.
7 . The stent of claim 1 , further comprising a tension line connecting a first side of the stent frame lattice to a second side of the stent frame lattice and extending across a lumen of the stent frame lattice along a minor dimension, the tension line being sized to physically hold the stent frame lattice in the biased first configuration or in the second configuration.
8 . The stent of claim 7 , wherein the tension line is at least partially composed of materials that dissolve within blood of a patient.
9 . The stent of claim 8 , wherein the tension line is sized to be percutaneously removed from the stent.
10 . The stent of claim 7 , wherein the tension line is a spring.
11 . The stent of claim 1 , wherein the non-circular cross-sectional shape has a constant angular orientation along a length of the stent frame lattice.
12 . The stent of claim 1 , further comprising one or more anchors extending from the stent frame lattice and sized to be deployed into engagement with tissue of a branch blood vessel that branches away from, and has a smaller diameter than, the pulmonary artery.
13 . The stent of claim 1 , further comprising a lining extending along the stent frame lattice to prevent flow of blood through the stent frame lattice.
14 . A system for providing compliance to a pulmonary artery, the system comprising:
a catheter comprising a catheter distal portion sized to be percutaneously advanced within a patient's vasculature to a pulmonary artery; and
a stent releasably secured to the catheter distal portion and comprising an elastically deformable stent frame lattice having a biased non-circular cross-sectional shape and being sized for placement in the pulmonary artery, the elastically deformable stent frame lattice forming a lumen extending between a first opening and a second opening of the stent frame lattice;
wherein the stent frame lattice is adapted to:
be percutaneously delivered into the pulmonary artery;
secure to a blood vessel wall of the pulmonary artery;
assume a biased first configuration outside a body of the patient, the biased first configuration defining an inner flow lumen characterized by a non-circular cross-sectional shape with inwardly-bowed minor-dimension sidewalls, the non-circular cross-sectional shape having a constant angular orientation along a length of the stent frame lattice and defining a first major diameter along a major dimension, a first central minor diameter along a minor dimension, and a first cross-sectional area;
upon deployment in the pulmonary artery, deform to a second configuration in response to diastolic pressure conditions, in which the stent frame lattice assumes an oval cross-sectional shape with outwardly-bowed minor-dimension sidewalls, a second major diameter, a second central minor diameter that is greater than the first central minor diameter, and a second cross-sectional area that is greater than the first cross-sectional area; and
in response to systolic pressure conditions, transition to a third configuration in which the stent frame lattice assumes a third major diameter along the major dimension that is less than the second major diameter, a third central minor diameter along the minor dimension that is greater than the second central minor diameter, and a third cross-sectional area that is greater than the second cross-sectional area,
wherein the stent comprises a tension line connecting a first side of the stent frame lattice to a second side of the stent frame lattice and extending across the inner flow lumen along the minor dimension, the tension line being sized to physically hold the stent frame lattice temporarily in the biased first configuration or the second configuration.
15 . The system of claim 14 , wherein the catheter distal portion comprises an expandable balloon sized to cause the stent frame lattice to radially expand.
16 . The system of claim 14 , wherein the catheter distal portion comprises a retractable sheath adapted to prevent the stent frame lattice from radially expanding to the second configuration.
17 . A device for providing compliance within a blood vessel, the device comprising:
a distal stent segment sized for placement in a blood vessel;
a proximal stent segment;
an elastically deformable middle stent segment positioned between the distal stent segment and the proximal stent segment, the middle stent segment being adapted to:
assume a biased first configuration outside of a body in which the middle stent segment has a non-circular cross-sectional shape with inwardly-bowed minor-dimension sidewalls, the non-circular cross-sectional shape defining a first major diameter along a major dimension, a first central minor diameter along a minor dimension, and a first cross-sectional area;
in response to diastolic pressure conditions within the blood vessel, transition to a second configuration in which the middle stent segment assumes an oval cross-sectional shape with outwardly-bowed minor-dimensional sidewalls, a second major diameter, a second central minor diameter that is greater than the first central minor diameter, and a second cross-sectional area that is greater than the first cross-sectional area; and
in response to systolic pressure conditions within the blood vessel, transition to a third configuration in which the middle stent segment assumes a third major diameter along the major dimension that is less than the second major diameter, a third central minor diameter along the minor dimension that is greater than the second central minor diameter, and a third cross-sectional area that is greater than the second cross-sectional area; and
a lining extending along the middle stent segment to prevent flow of blood through cells of the middle stent segment, the lining not extending along open cells of the distal stent segment or the proximal stent segment.
18 . The device of claim 17 , wherein the distal stent segment and the proximal stent segment are sized to be radially expanded into contact with an aortic wall of an aorta, and wherein the third cross-sectional area of the middle stent approximates a cross-sectional area of the aorta.
19 . The device of claim 17 , wherein the first major diameter is greater than the second major diameter.
20 . The device of claim 17 , wherein the distal stent segment and the proximal stent segment comprise a plastically deformable material.
21 . The device of claim 20 , wherein the distal stent segment and the proximal stent segment comprise stainless steel or a cobalt alloy, and the middle stent segment comprises nitinol.
22 . The device of claim 17 , wherein the non-circular cross-sectional shape is a peanut shape.
23 . The device of claim 17 , wherein the non-circular first cross-sectional shape is a kidney shape.
24 . A method of restoring compliance to a pulmonary artery, the method comprising:
providing a stent having a biased first configuration having a non-circular cross-sectional shape with inwardly-bowed minor-dimensional sidewalls, a first major diameter, a first central minor diameter, and a first cross-sectional area;
deploying the stent in the pulmonary artery such that diastolic pressure forces cause the stent to deform to a second configuration having an oval cross-sectional shape with outwardly-bowed minor-dimensional sidewalls, a second major diameter, a second central minor diameter that is greater than the first central minor diameter, and a second cross-sectional area that is greater than the first cross-sectional area;
increasing flow in the pulmonary artery by allowing the stent to respond to systolic pressure forces by transitioning from the second configuration to a third configuration having a more circular cross-sectional shape including a third major diameter that is less than the first and second major diameters, a third central minor diameter that is greater than the second central minor diameter, and a third cross-sectional area that is greater than the second cross-sectional area; and
cycling the stent between the second configuration and the third configuration in response to cyclically-changing luminal forces of the pulmonary artery on the stent to restore compliance to the pulmonary artery.
25 . The method of claim 24 , deploying the stent involves expanding an expandable balloon within a lumen of the stent.
26 . The method of claim 25 , wherein the stent is advanced through vasculature of a patient positioned on the expandable balloon.
27 . The method of claim 24 , slidingly positioning a sheath over the stent.
28 . The method of claim 24 , wherein after radially expanding deploying the stent, the stent is physically held by a restraint connecting a first side of the stent to a second side of the stent and extending across an inner flow lumen of the stent and sized to restrain the stent in the biased first configuration or in the second configuration.
29 . The method of claim 28 , wherein the method further comprises, releasing the restraint from the stent so that the stent is no longer held in the biased first configuration or in the second configuration, and can deform between the second configuration and the third configuration.
30 . The method of claim 29 , wherein the restraint comprises a tension line, and wherein releasing the restraint involves cutting the tension line.
31 . The method of claim 29 , wherein the restraint comprises an absorbable tension line, and wherein releasing the restraint occurs responsive to exposure of the absorbable tension line to blood.
32 . The method of claim 24 , wherein the non-circular cross-sectional shape has a constant angular orientation along a length of the stent.
33 . The method of claim 24 , wherein the stent further comprises one or more anchors extending from the stent, the method further comprising deploying the one or more anchors into engagement with tissue of a branch blood vessel that branches away from, and has a smaller diameter than, the pulmonary artery.
34 . The method of claim 24 , wherein the stent further comprises a lining extending along the stent to prevent flow of blood through a frame of the stent.
35 . A device for restoring pulmonary artery compliance, comprising:
a stent body comprising an elastically deformable stent frame lattice sized for placement in a pulmonary artery, wherein the stent frame lattice is adapted to:
assume a biased first configuration defining a non-circular cross-sectional shape with inwardly-bowed minor-dimension sidewalls, the non-circular cross-sectional shape having a constant angular orientation along a length of the stent frame lattice and defining a first major diameter along a major dimension, a first central minor diameter along a minor dimension, and a first cross-sectional area;
upon deployment in the pulmonary artery, deform to a second configuration in response to diastolic pressure conditions, in which the stent frame lattice assumes an oval cross-sectional shape with outwardly-bowed minor-dimensional sidewalls, a second major diameter, a second central minor diameter that is greater than the first central minor diameter, and a second cross-sectional area that is greater than the first cross-sectional area; and
in response to increasing luminal forces of the pulmonary artery on the stent frame lattice associated with systolic pressure conditions, transition to a third configuration in which the stent frame lattice assumes a third major diameter that is less than the second major diameter, a third central minor diameter that is greater than the second central minor diameter, and a third cross-sectional area that is greater than the second cross-sectional area; and
one or more anchors extending from the stent body and sized to be deployed into engagement with tissue of a branch blood vessel that branches away from, and has a smaller diameter than, the pulmonary artery.
36 . The device of claim 35 , wherein at least one of the one or more anchors extends from the stent body at a position between a first opening and a second opening of the stent body.
37 . The device of claim 35 , wherein at least one of the one or more anchors extends from at or near a first opening of the stent body.
38 . The device of claim 35 , wherein at least one of the one or more anchors comprises a wireform adapted to pass within the branch blood vessel and sized to engage wall tissue of the branch blood vessel.
39 . The device of claim 38 , wherein the wireform comprises a shape-memory material.
40 . The device of claim 35 , wherein at least one of the one or more anchors comprises an anchor stent body wherein the anchor stent body is sized to be radially expanded into contact with a wall of the branch blood vessel.
41 . The device of claim 40 , wherein the anchor stent body comprises a shape-memory material and is biased toward a configuration wherein the anchor stent body has the non-circular cross-sectional shape.
42 . The device of claim 40 , wherein the anchor stent body has an anchor stent body length between 0.5 and 7 cm.