Assembly for replacing the tricuspid atrioventricular valve
An assembly for the tricuspid orifice of a human heart has an external frame connected to an internal stent carrying a tricuspid valve bioprosthesis and a sealing skirt. The external frame is configured to hold its position in the native tricuspid annulus. The internal stent is connected to the external frame by one or more fixing strands. The sealing skirt covers the interstitial space existing between the external frame and the internal stent. Developments are described which include the use of a deformable region of the frame, various alternative embodiments of the sealing skirt, the use of a frame composed of multiple sub-sections, the use of fixing strands between the stent and the frame and of fixing elements for fixing the assembly to the native tissue, the use of sensors and/or actuators, and also the use of a stent in the inferior vena cava. Method aspects are also described.
1 . An assembly for a tricuspid orifice of a right side of a human heart, comprising
an external frame connected to
an internal stent carrying
a tricuspid valve bioprosthesis and
a sealing skirt,
wherein:
the external frame is configured to hold its position in a native tricuspid annulus between a ventricle and an atrium, the external frame having a ventricular end, an opposing atrial end and a middle portion, the external frame defining circumferential interstitial space between the external frame and the internal stent, the interstitial space between the internal stent and the external frame extending over an entire height of the internal stent;
the external frame having three zones of different diameters, the three zones comprising:
a first outward convex zone configured for arrangement in the ventricle;
a second outward convex zone configured for arrangement in the atrium, the second outward convex zone having a diameter greater than a diameter of the first outward convex zone;
a third zone separating the first and second outward convex zones and having a diameter smaller than the diameter of the first and second outward zones, the third zone being configured for arrangement at the annulus;
the internal stent has an atrial end, a ventricular end and a midportion therebetween, the internal stent is connected to the external frame by one or more fixing strands, the external frame and the internal stent being connected only by the one or more fixing strands;
the internal stent includes a plurality of rows of cells, a first row of cells of the plurality of rows of cells are formed having an elongated hexagonal shape, at least one row of cells of the plurality of rows of cells adjacent the first row of cells are formed having a generally rhombus shape;
each of the one or more fixing strands includes a first end and an opposite second end, the first end of each of the one or more fixing strands being coupled to the external frame, and the second end of each of the one or more fixing strands being coupled to the internal stent at the atrial end of the internal stent, at a position adjacent to the atrial end of the internal stent, or at the midportion;
the one or more fixing strands being flexible and ensuring the interstitial space between the internal stent and the external frame is maintained over the entire height of the internal stent; and
the sealing skirt comprises a fold extending from an interior surface of the third zone configured for arrangement in the annulus to the internal stent to cover the interstitial space existing between the external frame and the internal stent;
the sealing skirt is configured to obstruct a contact space between the external frame and a site of native tissue in a region of the native tricuspid annulus upstream of the annulus; and
the tricuspid valve bioprosthesis is operable to block flow in a direction from the ventricular end of the external frame to the atrial end of the external frame.
2 . The assembly according to claim 1 , wherein the external frame has a deformable region configured to hold the assembly in position inside the native tricuspid annulus.
3 . The assembly according to claim 1 , wherein the external frame has, upstream from the region of a native annulus, a shape configured to reinforce the hold of the assembly in the native tricuspid annulus.
4 . The assembly according to claim 1 , wherein the external frame has, downstream from a region of the native annulus, a shape configured to reinforce the hold of the assembly in the native tricuspid annulus.
5 . The assembly as claimed in claim 1 , wherein each of the one or more fixing strands is made of nitinol.
6 . The assembly according to claim 1 , further comprising at least one fixing element for fixing to the native tissue.
7 . The assembly according to claim 6 , wherein at least one of the frame, the internal stent, the one or more fixing strands, or the fixing element is composed of a heat-sensitive material, a shape-memory material, or a shape-memory material that is heat-sensitive.
8 . The assembly according to claim 1 , the sealing skirt being composed of several sub-sections, of several layers of materials, or of several sub-sections and several layers of material.
9 . The assembly according to claim 1 , further comprising at least one sensor, a radiopaque marker, or both the at least one sensor and the radiopaque marker.
10 . The assembly according to claim 1 , further comprising an actuator suitable for modifying a structure of the assembly, for adjusting a positioning of a part of the assembly with respect to the native annulus, or both for modifying the structure of the assembly and adjusting the positioning of the part of the assembly with respect to the native annulus.
11 . The assembly according to claim 1 , said assembly being connected to a further stent suitable for positioning in an inferior vena cava, said further stent being connected to the external frame of the assembly by a strand made of nitinol.
12 . The assembly according to claim 1 , said assembly being folded up in a packaged state in a catheter for introduction by a percutaneous route.
13 . The assembly according to claim 1 , wherein the first end of each of the one or more fixing strands are connected closer to the atrial end than to the ventricular end of the external frame.
14 . The assembly according to claim 1 , wherein the external frame extends outwardly with respect to the tricuspid valve bioprosthesis from the middle portion to the atrial end.
15 . The assembly according to claim 1 , wherein the external frame comprises a plurality of sub-sections that are independent of one another.
16 . The assembly according to claim 15 , wherein each of the plurality of sub-subsections comprises a loop, the loops not being interconnected with each other.
17 . The assembly according to claim 1 , wherein a diameter of the internal stent is on the order of 20% less than the diameter of the external frame in the region of the native tricuspid annulus.
18 . The assembly according to claim 1 , wherein the circumferential interstitial space between the external frame and the internal stent is a plurality of millimeters.
19 . The assembly according to claim 1 , wherein the external frame has a height greater than the height of the internal stent.
20 . The assembly according to claim 19 , wherein the atrial end of the external frame extends beyond the atrial end of the internal stent and the ventricular end of the external frame extends beyond the ventricular end of the internal stent.
21 . The assembly according to claim 19 , wherein the height of the external frame is between 32 and 45 mm.
22 . The assembly according to claim 1 , wherein the plurality of rows of cells includes a second row of cells adjacent the at least one row of cells on a side opposite the first row of cells.
23 . The assembly according to claim 1 , wherein the external frame includes an outer wall and an opposite inner wall facing the internal stent, and wherein the sealing skirt includes an inner portion, an outer portion, and an intra-atrial base portion connecting the inner portion and the outer portion, the inner portion covering a portion of the inner wall, the outer portion covering a portion of the outer wall, and the intra-atrial base portion covering the atrial end of the external frame so as to envelope a portion of the external frame.
24 . A method for replacing the tricuspid valve, comprising steps of positioning the assembly as claimed in claim 1 in a folded state in a catheter, and introducing and deploying said assembly by a percutaneous route.