Adjustable annuloplasty ring and delivery system
An annuloplasty ring for repair of mitral and tricuspid valves that can be shape adjusted once installed to fine-tune the shape and correct for small errors in the inherently imprecise sizing process. The ring has an adjustable 3D ring core of malleable metal that can be reshaped in real-time during the procedure before or after the patient is weaned off-pump by applying simple displacements to a cable and housing arrangement. The shape of the annuloplasty ring is adjusted incrementally in steps until an optimum level of regurgitation reduction is attained. Once the surgeon is satisfied with the result, the delivery system can be can easily detached from the implant and removed. The thickness of the core could be continuously variable to control how and where deformation occurs. The ring may also incorporate an expansion joint to enable a subsequent valve-in-ring procedure.
1 . An adjustable annuloplasty ring and delivery system, comprising:
an annuloplasty ring having a continuous peripheral shape around a central aperture, the annuloplasty ring having an inner core formed of an elastic-plastic metal having a yield strength and a suture-permeable interface surrounding the inner core and extending around the peripheral shape;
a delivery system including a flexible sheath coupled to the inner core at a first side of the annuloplasty ring, the sheath housing a flexible cable configured to slide through the sheath, the cable passing through the first side of the annuloplasty ring and extending across the central aperture to a diametrically-opposed second side of the annuloplasty ring, whereby the cable attaches securely to the inner core at the second side; and
an actuation mechanism at a proximal handle of the delivery system configured to pull the cable proximally relative to the sheath, and the inner core having cross-sectional dimensions and the yield strength being such that a dimension between the first and second sides is permanently reduced by a predetermined tension on the cable.
2 . The adjustable annuloplasty ring and delivery system of claim 1 , wherein the annuloplasty ring is shaped for implant at the mitral annulus and the peripheral shape is a rounded D-shape with a relatively straight anterior segment opposite an arcuate posterior segment, with a shorter minor axis extending between the anterior and posterior segments and a longer major axis extending perpendicular to the minor axis and between side segments, and wherein the first side is the anterior segment and the second side is the posterior segment.
3 . The adjustable annuloplasty ring and delivery system of claim 2 , wherein the inner core has a radial thickness in the anterior segment that is greater than a radial thickness in the posterior segment.
4 . The adjustable annuloplasty ring and delivery system of claim 3 , wherein the inner core has an axial thickness in the side segments that is greater than axial thicknesses in both the anterior and the posterior segments.
5 . The adjustable annuloplasty ring and delivery system of claim 4 , wherein the elastic-plastic metal has a yield strength less than about 300 MPa.
6 . The adjustable annuloplasty ring and delivery system of claim 5 , wherein the elastic-plastic metal is a titanium alloy.
7 . The adjustable annuloplasty ring and delivery system of claim 3 , wherein the inner core has a rectangular cross-sectional shape.
8 . The adjustable annuloplasty ring and delivery system of claim 1 , wherein the inner core has at least one expansion joint around the peripheral shape which permits expansion of the inner core upon application of a dilatory force greater than normal physiological forces imparted to the inner core from a surrounding annulus.
9 . The adjustable annuloplasty ring and delivery system of claim 1 , wherein the sheath and cable form a primary shape adjustment mechanism, and the delivery system further includes a secondary shape adjustment mechanism including a flexible second sheath with a second cable configured to slide through the second sheath, the second cable passing through a third side of the annuloplasty ring and extending across the central aperture to a diametrically-opposed fourth side of the annuloplasty ring, whereby the second cable attaches securely to the ring core at the fourth side, and wherein the first cable and second cable cross the central aperture at about a 90° angle with respect to each other.
10 . The adjustable annuloplasty ring and delivery system of claim 1 , wherein the inner core has a rectangular cross-sectional shape and is radially thicker in the first side than in the second side, and the peripheral shape is three-dimensional forming a saddle with the first and second sides bowed upward from intermediate segments therebetween, and wherein the inner core is axially thicker in the intermediate segments that it is in the first and second sides.
11 . An adjustable annuloplasty ring and delivery system, comprising:
an annuloplasty ring having a continuous peripheral shape around a central aperture, the annuloplasty ring having an inner core formed of an elastic-plastic metal having a yield strength and a suture-permeable interface surrounding the inner core and extending around the peripheral shape, the inner core having at least one expansion joint around the peripheral shape which permits expansion of the inner core upon application of a dilatory force greater than normal physiological forces imparted to the inner core from a surrounding annulus but restricts contraction of the inner core at the expansion joint;
a delivery system including a flexible sheath coupled to the inner core at a first side of the annuloplasty ring, the sheath housing a flexible cable configured to slide through the sheath, the cable extending across the central aperture to a second side of the annuloplasty ring, whereby the cable attaches securely to the inner core at the second side; and
an actuation mechanism at a proximal handle of the delivery system configured to pull the cable proximally relative to the sheath, and the inner core having cross-sectional dimensions and the yield strength being such that a dimension between the first and second sides is permanently reduced by a predetermined tension on the cable.
12 . The adjustable annuloplasty ring and delivery system of claim 11 , wherein the annuloplasty ring is shaped for implant at the mitral annulus and the peripheral shape is a rounded D-shape with a relatively straight anterior segment opposite an arcuate posterior segment, with a shorter minor axis extending between the anterior and posterior segments and a longer major axis extending perpendicular to the minor axis and between side segments, and wherein the first side is the anterior segment and the second side is the posterior segment.
13 . The adjustable annuloplasty ring and delivery system of claim 12 , wherein the inner core has a radial thickness in the anterior segment that is greater than a radial thickness in the posterior segment.
14 . The adjustable annuloplasty ring and delivery system of claim 13 , wherein the inner core has an axial thickness in the side segments that is greater than axial thicknesses in both the anterior and the posterior segments.
15 . The adjustable annuloplasty ring and delivery system of claim 14 , wherein the elastic-plastic metal has a yield strength less than about 300 MPa.
16 . The adjustable annuloplasty ring and delivery system of claim 15 , wherein the elastic-plastic metal is a titanium alloy.
17 . The adjustable annuloplasty ring and delivery system of claim 13 , wherein the inner core has a rectangular cross-sectional shape.
18 . The adjustable annuloplasty ring and delivery system of claim 12 , wherein the expansion joint is centered in the posterior segment.
19 . The adjustable annuloplasty ring and delivery system of claim 12 , wherein the expansion joint is centered in the anterior segment.
20 . The adjustable annuloplasty ring and delivery system of claim 12 , wherein there are two of the expansion joints each centered in one of the side segments.
21 . The adjustable annuloplasty ring and delivery system of claim 11 , wherein the inner core has two expansion joints spaced around the peripheral shape.
22 . The adjustable annuloplasty ring and delivery system of claim 11 , wherein the sheath and cable form a primary shape adjustment mechanism, and the delivery system further includes a secondary shape adjustment mechanism including a flexible second sheath with a second cable configured to slide through the second sheath, the second cable passing through a third side of the annuloplasty ring and extending across the central aperture to a diametrically-opposed fourth side of the annuloplasty ring, whereby the second cable attaches securely to the ring core at the fourth side, and wherein the first cable and second cable cross the central aperture at a 90° angle with respect to each other.
23 . The adjustable annuloplasty ring and delivery system of claim 11 , wherein the inner core has a rectangular cross-sectional shape and is radially thicker in the first side than in the second side, and the peripheral shape is three-dimensional forming a saddle with the first and second sides bowed upward from intermediate segments therebetween, and wherein the inner core is axially thicker in the intermediate segments that it is in the first and second sides.
24 . The adjustable annuloplasty ring and delivery system of claim 11 , wherein the expansion joint comprises two overlapping free ends of the inner core.
25 . The adjustable annuloplasty ring and delivery system of claim 11 , wherein the expansion joint comprises two abutting free ends of the inner core having circumferential channels in which an expansion insert slides.
26 . The adjustable annuloplasty ring and delivery system of claim 11 , wherein the expansion joint has a stop which limits a maximum expansion of the inner core.