Flexible Delivery System

Abstract

An articulated device for advancing a medical implant along a catheter comprises a plurality of segments (1, 12) arranged one after the other in line, each segment being hingeably connected to a single adjacent segment if it is at the end of the line and otherwise to two adjacent segments, whereby a medical implant mounted at one end of the device can be advanced through a catheter by pushing on the other end of the device, the hinged connections allowing the device to follow a curved path through the catheter.

Description

A number of preferred embodiments of the invention will now be described with reference to the drawings, in which:

FIG. 1 illustrates a basic segmental retainer rod comprising simple, plane-faced cylindrical segments;

FIG. 2 illustrates an improved version of FIG. 1 in which the abutting faces have been chamfered to enable a greater degree of flexion to take place without a significant change in length occurring;

FIG. 3 illustrates a segment suitable for a device in accordance with the invention; and

FIG. 4 illustrates two segments of the type shown in FIG. 3 connected as they would be in a device in accordance with the invention.

Turning first to FIG. 3, this illustrates a practical design of segment which employs the characteristics shown in FIGS. 1 and 2 but which includes additional features to transmit torque, to allow additional longitudinal structures and to maximise the smoothness of the outer sheath when flexed.

Segment 1 comprises an integral elongate element formed of a glass-reinforced polyphenylene sulphide with a length of approximately 10.5 mm and a width at its widest point of approximately 6 mm.

Segment 1 has male part 2 and female part 3 which meet at neck 4, and is configured so that male part 2 of one segment engages with female part 3 of an adjacent segment. A plurality of segments can therefore be linked end-to-end by connecting corresponding male and female parts.

In particular, male part 2 comprises ball 5 having pair of lugs 6 projecting laterally therefrom in an axis orthogonal to the longitudinal axis of segment 1. Female part 3 has socket joint 9 with lip 11, and a pair of slots 10 substantially parallel to the longitudinal axis of segment 1.

The mouth of each slot 10 is slightly narrower than the width of each lug 6, so that a slight force needs to be applied to the lug 6 to force the jaws of each slot 10 to flex slightly and move apart to allow lug 6 to pass therebetween. Each slot 10 then widens slightly beyond its mouth to accommodate each lug 6 in a sliding fit.

In use, lugs 6 of an adjacent segment can be slotted into slots 10 so as to seat ball 5 in socket 9 to form a ball and socket joint.

It will be appreciated that female part 3 is laterally wider than male part 2 which has to be sized so as to fit into female part 3. Accordingly, it is the outer surface of female part 3 that is more likely to come into contact with the inner wall of a catheter into which segment 1 has been inserted, and it is for this reason that outer walls 8 of female part 3 are curved so as to provide a smooth surface for rebutting the inner wall of the sheath even under extreme degrees of flexion.

A lumen (not shown) is provided along the longitudinal axis of the segment at or close to the centre, to allow a guide wire and surrounding structures to pass therethrough.

Two cut-out channels 7 are provided in the outer wall of female part 3 of segment 1 to allow for the use of other guide wires or similar structures.

Turning to FIG. 4, two identical segments 1 and 12 are shown in a connected state with lugs 6 of segment 12 fully inserted into slots 10 of segment 1 and ball 5 of segment 12 (not shown) seated in socket 9 of segment 1 (not shown).

It can be seen from FIG. 4 that the width of neck 4 is less than the internal diameter of the mouth of socket joint 9, and thus there is sufficient space for segment 12 to rotate about the axis of its lugs 6 thereby allowing a degree of articulation between segment 1 and segment 12. In FIG. 4, segments 1 and 12 are shown in their fully flexed state, with segment 12 being rotated by about 15 degrees so that the outer surface of neck 4 of segment 12 abuts lip 11 of segment 1.

In use, between 15 and 80 segments are linked as shown in FIG. 4, the number depending on the length of the catheter into which the device is to be inserted. A medical implant is mounted on the end segment, which may be modified so as to receive the implant. At the end of the device distal to the implant, a modified segment having handles is employed, the handles being used to apply force to the device both along its longitudinal axis (to advance the implant through the catheter) and to rotate the device about its longitudinal axis so as to apply torsional force to rotate the implant. Such torsional force can be applied along the length of the device because of the lack of play between lugs 6 and slots 10 of adjacent segments.

In order to implant a stent graft, for example, in vivo, the stent graft is mounted on the end of a device according to the invention and is then inserted into an outer sheath and advanced until the stent graft is at the end of the outer sheath distal from the operator. The outer sheath can then itself be advanced down a catheter, and a catheter inserted into the vascular tree. When the distal end of the outer sheath is at the required implant site, the sheath is pulled slowly backwards with the stent graft being held in place by the inventive device. The operator can easily rotate the stent graft so as to place it accurately by rotating the handle at the end of the device. Moreover, pressure applied to the sheath in order to deploy the stent graft does not cause compression of the device, in contrast to prior art devices. Thus the device according to the invention can be successfully employed to implant stent grafts in vivo.

Claims

1. An articulated device for advancing a medical implant along a catheter, the device comprising a plurality of segments arranged one after the other in line, each segment being hingeably connected to a single adjacent segment if it is at the end of the line and otherwise to two adjacent segments, whereby a medical implant mounted at one end of the device can be advanced through a catheter by pushing on the other end of the device, the hinged connections allowing the device to follow a curved path through the catheter, characterised in that each segment is detachable from its adjacent segment(s).

2. A device as claimed in claim 1, wherein each segment comprises a male part and a female part, the male part of a segment being able to engage with the female part of an adjacent segment, and the female part being able to engage with the male part of an adjacent segment.

3. A device as claimed in claim 2, wherein the male part comprises a pair of projections and the female part comprises a slot for accepting the projections.

4. A device as claimed in claim 2, wherein the male part comprises a ball and the female part comprises a socket.

5. A device as claimed in claim 1, wherein the segments are formed from a material which is sufficiently stiff to allow a moment of at least 1 Newton metre to be transmitted through the device.

6. A device as claimed in claim 1 which includes from 15 to 80 segments.

7. A device as claimed in claim 1, wherein each segment has a lumen passing through its body along its longitudinal axis, so that the plurality of lumen substantially align to allow a guide wire to pass therethrough when the device is in use.

8. A device as claimed in claim 1, wherein each segment has a channel in its outer wall so that the plurality of channels substantially align to allow a guide wire to pass therethrough when the device is in use.

9. A device as claimed in claim 1, wherein the ratio of the length to the widest diameter of each segment is in the range 1:1 to 1:5.

10. A device as claimed in claim 1, wherein the maximum degree of articulation between the longitudinal axis of one segment and the longitudinal axis of an adjacent segment is at least 15.

11. A device as claimed in claim 1 in combination with a medical implant mounted on one end of the device.

12. A device as claimed in claim 11 wherein the medical implant is a vascular graft.

13. The device of claim 11 further comprising a delivery catheter.

14. (canceled)

15. A method of advancing a medical implant along a catheter comprising providing a device as claimed in claim 1 having an implant mounted on one end of the device, inserting said end of the device into the catheter, and pushing on the other end of the device.

16. An articulated device for advancing a medical implant along a catheter, the device comprising: a. a catheter having a catheter interior passage;b. multiple segments adjacently arrayed in a line within the catheter interior passage, wherein: (1) each segment pivotally abuts any adjacent segments, whereby the line of segments may adopt a curved path within the catheter, and(2) the segments are translatable within the passage, whereby the segment at one end of the line can: (i) have a medical implant situated thereon, and(ii) be advanced through at least a major portion of the length of the catheter interior passage to eject the medical implant from a passage exit.

17. The articulated device of claim 16 further comprising a passage defined within each segment, wherein the passages are aligned when the segments are arrayed in a line to define a passage extending axially along the arrayed segments.

18. The articulated device of claim 17 wherein the passage in each segment is situated on the outer circumference of each segment.

19. The articulated device of claim 17 wherein the passage in each segment extends through each segment spaced from the segment's outer circumference.

20. The articulated device of claim 16 further comprising a tube extending through the segments.

21. The articulated device of claim 19 wherein the tube is affixed to at least two segments which are spaced by intermediate segments.

22. The articulated device of claim 16 wherein each segment is resiliently snap-fit to at least one adjacent segment.

23. The articulated device of claim 16 wherein each segment bears one or more projections, each projection being engaged to an adjacent segment.

24. The articulated device of claim 22 wherein each segment bears a ball thereon, and wherein the projections extend from the ball.

25. The articulated device of claim 16 wherein segments have lengths, as measured along the line, which are less than or equal to their diameters.

26. The articulated device of claim 16 wherein segments have diameters of approximately 10 mm or less.