WO2005027750A1

WO2005027750A1 - Snare for blood vessels used in anastomotic procedures

Info

Publication number: WO2005027750A1
Application number: PCT/IL2003/000773
Authority: WO
Inventors: Amir Loshakove; Ido Kilemnik; Ofer Nativ
Original assignee: By-Pass, Inc.
Priority date: 2003-09-25
Filing date: 2003-09-25
Publication date: 2005-03-31
Also published as: AU2003264854A1

Abstract

A snare (100) for snaring a blood vessel, comprising a handle, a first extension (130) from said handle, a second extension (122) from said handle and a sharp tip (136) at the end of said second extension and configured to contact said first extension, said sharp tip being adapted to impale vascular tissue without causing substantial tearing beyond said piercing.

Description

SNARE FOR BLOOD VESSELS USED IN ANASTOMOCTIC PROCEDURES

FIELD OF THE INVENTION The present invention relates to devices for use when performing an anastomosis and/or other blood vessel manipulation. BACKGROUND OF THE INVENTION Connecting a grafted vessel to an anastomotic connector in preparation for anastomosis with a host vessel is a delicate procedure. One type of anastomotic connector comprises a ring, typically having a diameter of 2.5 millimeters or less, and 8-14 delicate legs arranged around the ring. The grafted vessel is typically pulled through the center of the ring and impaled on the legs in preparation for anastomotic connection. Pulling a grafted vessel with a standard forceps, for example a tweezers, could easily result in a crush injury to the vessel tissue as a result of inordinate squeezing of the tweezers by the operator. Tissue injury may result in scarring and/or blockage in the healed anastomosed vessel. In addition, the manipulation of the graft using tweezers may require additional dexterity, to prevent the vessel from slipping off during manipulation. SUMMARY OF THE INVENTION An aspect of some embodiments of the invention relates to a snare for snaring a grafted vessel and pulling it through the center of an anastomotic connector. In an exemplary embodiment, the snare comprises a sharp tip which engages the snared vessel by impaling it, optionally preventing crushing of the vessel and/or contact with any significant portion of the vessel. Optionally, the snare comprises two surfaces that are spring loaded to at least contact each other. In use, a vessel is mounted on one of the surfaces and when the surfaces contact, inadvertent release of the vessel is prevented. Optionally, the vessel is mounted by pushing it between the surfaces so that the sharp tip impales the vessel and then the surfaces at least contact to lock the vessel on the snare. Optionally, removal is by further advancing the vessel, so it pulls off the tip and can be slid out between the surfaces. By "at least contact" is meant that the two surfaces may contact each other or may go past each other, for example the sharp tip may pass through an aperture in the other surface. In an exemplary embodiment of the invention, the two surfaces do not move one relative to the other except towards each other. In an alternative embodiment of the invention, a sheath is provided which can be selectively advanced towards the tip. Optionally, the grafted vessel is placed on the sharp tip and the tip is retracted into the sheath so the vessel becomes snared between the tip and the end of the sheath. This may be practiced even with a non-sharp tip. In an exemplary embodiment, the end of the sheath comprises an extension lip that curves radially away from the longitudinal axis of the sheath and the tip projects from the shaft at an oblique angle to the tip. Optionally, the lip comprises a groove adapted to receive the tip. Optionally, the sheath may be positioned to control the elastic urging force between the two surfaces. In an exemplary embodiment, the snare is adapted for passing through an anastomotic connector that is mounted on an anastomotic connector system, for, example, via a portal on the system. Optionally, the sheath encloses a longitudinal channel that, when connected to a pneumatic liquid, cause retraction of the tip. In an exemplary embodiment of the invention, the snare comprises two or more jaws that are forced towards each other by the retraction thereof relative to a sheath. There is thus provided in accordance with an exemplary embodiment of the invention, a snare for snaring a blood vessel, comprising: a handle; a first extension from said handle; a second extension from said handle; and a shaφ tip at the end of said second extension and configured to interface with said first extension, said sharp tip being adapted to impale vascular tissue without causing substantial tearing beyond said piercing. Optionally, said extensions are elastically predisposed to interface each other at said tip. Optionally, said elastic disposition is configured to ensure impaling by said tip of a blood vessel placed said tip and said first extension. Alternatively or additionally, wherein said elastic disposition is configured to prevent slipping off of said vessel after impaling under normal manipulation of said vessel. In an exemplary embodiment of the invention, said interfacing comprises contacting. Alternatively or additionally, said tip is hooked. In an exemplary embodiment of the invention, the snare comprises a second sharp tip at the end of said first extension, being configured to interface with said first tip, said second shaφ tip being adapted to impale vascular tissue without causing substantial tearing beyond said piercing. Optionally, said two tips are elastically pre-disposed to contact each other.

Alternatively or additionally, the snare comprises an overtube adapted to be advanced over said extensions to bring the tips together. In an exemplary embodiment of the invention, said first extension defines a receptacle for said tip. Alternatively or additionally, said first extension is formed of a same element as said handle. Alternatively or additionally, said first extension is more rigidly attached to said handle than said second extension, such that said first extension tends to deflect less than said second extension under a same force applied at their contact point. Alternatively or additionally, said handle comprises a tube and wherein said second extension is mounted in a lumen of said tube. Optionally, said tip does not move relative to said handle except in a direction peφendicular to a main axis of said handle. Alternatively, said tip moves towards said first extension in response to a retraction of said first extension into said handle. In an exemplary embodiment of the invention, said handle is plastically deformable.

Alternatively or additionally, said handle is flexible. Alternatively or additionally, said handle has a diameter smaller than a coronary graft vessel. Optionally, said handle has a diameter smaller than 5 mm at a distance of 4 cm from said extension. Optionally, said handle has a diameter smaller than 3 mm at a distance of 4 cm from said extension. In an exemplary embodiment of the invention, said handle has a diameter smaller than 3 mm at a distance of 10 cm from said extension. In an exemplary embodiment of the invention, said snare comprises a protector adjacent said tip and configured to protect a snared vessel from damage at its end. There is also provided in accordance with an exemplary embodiment of the invention, a method of mounting a graft vessel on an anastomosis delivery system, comprising: impaling said vessel on a shaφ tip adapted to cause minimal trauma to said vessel; pulling said tip and said vessel through an aperture in the side of a delivery system; and removing said vessel from said shaφ tip. Optionally, the method comprises interfacing said tip with a surface to prevent said vessel from falling off said tip. Optionally, interfacing comprises elastically contacting. Alternatively or additionally, impaling comprises placing said vessel between said shaφ tip and a surface, which tip and surface are elastically predisposed to move towards each other, with sufficient force to impale said vessel. BRIEF DESCRIPTION OF THE FIGURES Non-limiting embodiments of the invention will be described with reference to the following description of exemplary embodiments, in conjunction with the figures. The figures are generally not shown to scale and any sizes are only meant to be exemplary and not necessarily limiting. In the figures, identical structures, elements or parts that appear in more than one figure are preferably labeled with a same or similar number in all the figures in which they appear, in which: Fig. 1 is a cross-sectional view of a vessel snare and its parts, in accordance with an exemplary embodiment of the invention; Figs. 2 and 3 are isometric views of a portion and an element of the vessel snare of Fig. 1, in accordance with an exemplary embodiment of the invention; Figs. 4 and 5 are isometric and cross-sectional views, respectively, of the snare of Figs. l-3in use snaring a vessel, in accordance with an exemplary embodiment of the invention; and Figs. 6A-6E illustrate a two jaw snare, in accordance with an exemplary embodiment of the invention. DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS Single Prong Snare Fig. 1 is a cross-sectional view of a grafted vessel snare 100 comprising a tube 180 having a channel 192 into which a shaft 122 is inserted, in accordance with an exemplary embodiment of the invention. Shaft 122 comprises a crook 120 at an end having a tip 136 that is adapted to impale a graft vessel 140 (Fig. 4). In an exemplary embodiment of the invention, a vessel is snared by being impaled by tip 136, for example using forceps. In an exemplary embodiment, tube 180 comprises a lip 130 extending from one end thereof, lip 130 curving radially away from the axis of shaft 122. Lip

130 thus prevents an impaled vessel from sliding off of tip 136. In an exemplary embodiment of the invention, shaft 122 is elastic. Alternatively or additionally, lip 130 is elastic.

Optionally, tip 136 causes lip 130 to bend away and, if formed of an elastic material, be urged elastically against tip 136. In some embodiments, tip 136 is made soft enough to also bend elastically under the urging of lip 130, in one embodiment, allowing lip 130 to remain substantially straight and, in another, such that both lip 130 and shaft 122 bend. Other structures may be used where a shaφ tip 136 is elastically urged against a surface 130. In an exemplary embodiment, crook 120 projects from shaft 122 at an oblique angle. This may control the degree of force between tip 136 and lip 130. Optionally, tip 136 is hooked backward. Optionally, the elasticity of shaft 122 allows graft vessel 140 to slip off of snare 100 if it is pulled too hard, rather than tear or otherwise be damaged. Optionally, the elasticity is selected to match a desired fail point. Alternatively or additionally, the elasticity is selected to be sufficient to drive tip 136 into a blood vessel placed between tip 136 and lip 130. In some embodiments of the invention, shaft 122 can retract into channel 192, in which case the contact force between lip 130 and tip 136 becomes greater. Various methods may be used for extending and retracting crook 120. In an exemplary embodiment, channel 192, for example, is connected to a pneumatic air supply that creates pressure or suction, causing extension or retraction of shaft 122 with respect to tube 180. In an exemplary embodiment of the invention, the supply comprises a small bulb-balloon which is compressed or released by hand. Alternatively or additionally, an optional pull/push wire 102 is used to advance and/or retract crook 120. As shown in Fig. 4, the actual path of snare 100 may be curved, especially if contact between the blood vessel and the delivery system and or anastomosis connector are not desired. In an exemplary embodiment of the invention, snare 100 is flexible to accommodate such a curve. Alternatively or additionally, snare 100 is plastically deformable to achieve a desired curve. In an exemplary embodiment of the invention, wire 102 is plastically deformable. Alternatively or additionally, an optional plastically deformable outer sheath 103 is provided. Fig. 3 is an enlarged view of shaft 122 showing an optional fold 128 in shaft that forms a thickening 124. Thickening 124 increases the size of the portion of the shaft in channel 192 and may be useful, for example, to improve sealing (e.g., for pneumatic or hydraulic based retraction) or for providing friction against the inside of channel 192. In an alternative, non- pneumatic embodiment, fold 128 extends beyond the rear end of channel 192 and thickening 124 serves as a manipulation handle. In a non-retracting embodiment, the thickening serves to anchor crook 120 in channel 192. Alternatively, adhesive may be used, optionally, a solid material is used rather than a tube for element 180. Fig. 2 is an enlarged isometric view of the end of snare 100 showing an optional groove 134 against which tip 136 interfaces during operation of snare 100. Fig. 4 shows a tip of a delivery system 1100, at one end of which project a plurality of connector legs 228, each of which includes a hook 220 on which it is desired to evert graft vessel 140. Graft vessel 140 needs to be conveyed between an aperture 1180 formed in a forward section 1160 of delivery system 1100 and an opening 150 formed between legs 228. As shown, snare 100 is guided into opening 150 and out of aperture 1180, to reach graft vessel 140. Graft vessel 140 is placed onto tip 136, for example manually or using tweezers. Possibly, the act of placing transfixes a section 170 of graft vessel 140 with tip 136. In an exemplary embodiment of the invention, graft vessel 140 is pulled using tweezers, for example, between tip 136 and lip 130. In the example shown, an opening 110 of graft vessel 140 surrounds tip 136. Tip 136 impales section 170 of the vessel and is then advanced to lip 130 to prevent the vessel from falling off. No manual manipulation of snare 100 is thus required. Lip 130 is shown moved aside an exaggerated amount, for clarity. It should be noted that legs 228 point forward. In an exemplary embodiment of the invention, a leg compacting system is used after or before graft vessel 140 is provided through opening 150, in order to make eversion easier. This is described, for example, in a PCT application filed on even date in the Israel receiving office of the PCT, having an attorney docket number 088/03504, by a same applicant "By-Pass Inc." and being titled "ANASTOMOTIC LEG ARRANGEMENT", the disclosure of which is incoφorated herein by reference. Fig. 5 is a cross-sectional view showing graft vessel 140 provided between legs 228 of a connector 104, and snare 100 released, for example. In an exemplary embodiment of the invention, snare 100 is released from graft vessel 140 by placing an object, such as tweezers between shaft 122 and the graft, thereby pushing graft vessel 140 off of tip 136 and also pushing lip 130 out of the way (and/or bending shaft 122). Alternatively, pulling of graft vessel 140 will release it from tip 136, so it can be slid out from between tip 136 and lip 130. Thereafter, optionally, graft vessel 140 is everted over hooks 220. Two jaw snare Figs. 6A-6E illustrate a two jaw snare 600, in accordance with an exemplary embodiment of the invention. Fig. 6A shows a jaw section 602 which comprises a single wire bent to have an elongate shaft 601, with the two ends of the wire formed into opposing jaws 604 and 606 and having respective opposite and optional pointed tips 608 and 610. Other manufacturing methods may be used, for example, welding the jaws on an elongate element and cutting from a metal strip. Fig. 6B shows snare 600 in an open condition, with Fig. 6C being a detail of the jaws.

In the embodiment of Fig. 2B, an optional fixed handle 612 is fixed to a proximal end of jaw section 602, for example being provided as an over tube. A sliding handle section 614 is provided over a distal section of jaw section 602. A portion of shaft 601 can be seen between the handle sections, however this is not essential. Fig. 6C shows detail of the jaws, in particular, a first optional feature that jaws 604 and

606 curve away and back towards each other and a second optional feature that two or more differently angled sections 620 and 624 (and corresponding 622 and 626) are provided. A distal section of sliding handle 614 is marked as ring 616, however it is noted that not all of handle 614 needs to slide relative to shaft 601, only ring 616 or its equivalent. Fig. 6D shows snare 600 when handle 612 is retracted relative to ring 616. Fig. 6E is a detail of the jaws in this state. Angled sections 620 and 622 contact an inner part of ring 616 and cause ring 616 to expand and/or cause jaw tips 608 and 610 to move towards each other.

Optionally an over-ring (not shown) or a change in the elasticity or plasticity of ring 616 is provided to limit the radial expansion of ring 616. As shown in Fig. 6E, in a final state, also angled sections 624 and 626 are retracted into ring 616, which is somewhat expanded thereby. In the embodiment shown, two different ring contacting angled sections are provided in each jaw. However, other angles and more or fewer sections can be used. In some embodiments, what is desired is to, at first, rapidly close the jaws and later, apply a greater force. This desire is achieved by the design shown. Alternatively or additionally, it may be desired to provide a space 630, which allows the target blood vessel to be engaged without crushing, only piercing it at one point thereof. Optionally, as in snare 100, a vessel can be snared by placing it between jaws 604 and 606. Ring 616 may be used for locking after snaring, or to control the degree of elasticity. In an exemplary embodiment of the invention, the curving out of sections 624 and 626 has a benefit of pushing aside (or away from) obstacles which might otherwise catch on graft vessel 140. Optionally, in snare 100 (Fig. 1), lip 130 serves this same protective function of sliding past obstacles. Optionally, lip 130 is made wider and curved to be an extension of tube

180, with a larger diameter, so that it may be used as a cover to protect the tip of graft vessel

140. In an alternative embodiment, a larger diameter cup or overtube is slid over shaft 180 to cover the tip of graft vessel 140. Such a cup or tube is optionally friction coupled to shaft 180. It should be noted that more than two jaws, for example three or more jaws may be provided in an alternative snare. In an alternative embodiment, a tweezers with an elastic closing spring is used, with the ends of the tweezers modified to include at least one, and optionally two opposing shaφ tips adapted to impale a blood vessel. In another embodiment of the invention, snare 100 or snare 600 is used for manipulating lips of an aperture, for example for moving them aside. In this usage, a relatively rigid shaft may be desirable. Exemplary Snare Specifications In an exemplary embodiment, lip 130 and tip 136 (Fig. 1) are designed to interface so that vessel 140 is supported by lip 130 as it is pierced by tip 136. While a contact interfacing is shown, in an alternative embodiment, an aperture for tip 136 is provided in lip 130. Optionally, extension lip 130, crook 120 and/or tip 136 are of appropriate size and materials to snare, for example the Left Interior Mammary Artery (LIMA) or Right Interior Mammary Artery (RIMA). Alternatively or additionally snare 100 may be used with various other types of grafts, including, for example, artificial grafts, xenografts and harvested veins and harvested arteries other than the LIMA and RIMA. Tip 136 and/or various dimensions and/or properties of the snare (100 or 600) may be varied for different graft vessel types. In an exemplary embodiment of the invention, tip 136 is formed or polished (e.g., using electro-polish) to prevent it from having shaφ edges besides its very tip. Thus, the danger of tearing is reduced. In one example, tip 146 (or snare 600) are formed from a wire having a diameter of 0.2 mm. Snare 100, for example, may be formed of a wire having a rectangular profile of 0.4 x 0.25 mm. Optionally, crook 120 may be coated with a material that allows relatively friction-free piercing of a tissue. Optionally, crook 120 is formed of stainless steel. Optionally, extension lip 130 may comprise flexible materials that reduce trauma to vessel 140, for example, Nylon and PIB AX (a variant of Nylon) . In an exemplary embodiment, channel 192 comprises a projection (not shown) that stops excessive retraction of tip 136, thereby preventing damage to vessel 140. Alternatively or additionally, lip 130 is curved with respect to tip 136 so that even when shaft 120 is maximally retracted, the pressure of tip 136 against vessel 140 is limited. Optionally, tube 180 comprises a material, for example PIB AX, that allows relatively friction-free motion through anastomotic connector portal 1180, connector base ring 104 and/or adjacent biological tissue. Alternatively or additionally snare 100 may be sized for use in a variety of surgical applications, for example for use in connecting larger vessels.

Additionally or alternatively the snare may be adapted to a wide variety of arranging systems

1100 and/or system portals 1180, for example comprising a rectangular or oval portal 1180. It will be appreciated that the above described methods and devices for snaring a graft vessel may be varied in many ways, including, changing the order of steps and the materials used for the devices. Further, a plurality of embodiments are described and the scope of the present invention includes embodiments without all of the described features (for example, without alternative or additional features) and embodiments which include features from two or more described embodiments. In addition, some of the features of the invention described herein may be adapted for use with other devices than those used for illustration, in accordance with other exemplary embodiments of the invention. The particular geometric forms used to illustrate the invention should not be considered as limiting the invention in its broadest aspect to only those forms.

For example, where a circular sheath is shown, in other embodiments an oval or square sheath may be used. Section heads, where provided, are used for clarity of navigation and are not meant to limit the embodiments described therein to only the particular limitations of the section headings. In some embodiments of the invention, a device is packaged (e.g., in a sterile package) and/or sold with an instruction leaflet, describing the device dimensions and/or situations for which the device should be applied. Measurements are provided to serve only as exemplary measurements for particular cases. The exact measurements applied will vary depending on the application. When used in the following claims, the terms "comprises", "comprising", "includes", "including" or the like means "including but not limited to". It will be appreciated by a person skilled in the art that the present invention is not limited by what has thus far been described. Rather, the scope of the present invention is limited only by the following claims.

Claims

1. A snare for snaring a blood vessel, comprising: a handle; a first extension from said handle; a second extension from said handle; and a shaφ tip at the end of said second extension and configured to interface with said first extension, said shaφ tip being adapted to impale vascular tissue without causing substantial tearing beyond said piercing.

2. A snare according to claim 1 wherein said extensions are elastically predisposed to interface each other at said tip.

3. A snare according to claim 2 wherein said elastic disposition is configured to ensure impaling by said tip of a blood vessel placed said tip and said first extension.

4. A snare according to claim 2 wherein said elastic disposition is configured to prevent slipping off of said vessel after impaling under normal manipulation of said vessel.

5. A snare according to any of claims 1-4, wherein said interfacing comprises contacting.

6. A snare according to any of claims 1-5, wherein said tip is hooked.

7. A snare according to any of claims 1-6, comprising a second shaφ tip at the end of said first extension, being configured to interface with said first tip, said second shaφ tip being adapted to impale vascular tissue without causing substantial tearing beyond said piercing.

8. A snare according to claim 7, wherein said two tips are elastically pre-disposed to contact each other.

9. A snare according to claim 7 or claim 8, comprising an overtube adapted to be advanced over said extensions to bring the tips together.

10. A snare according to any of claims 1-6, wherein said first extension defines a receptacle for said tip.

11. A snare according to any of claims 1-10, wherein said first extension is formed of a same element as said handle.

12. A snare according to any of claims 1-11, wherein said first extension is more rigidly attached to said handle than said second extension, such that said first extension tends to deflect less than said second extension under a same force applied at their contact point.

13. A snare according to any of claims 1-12, wherein said handle comprises a tube and wherein said second extension is mounted in a lumen of said tube.

14. A snare according to claim 13, wherein said tip does not move relative to said handle except in a direction peφendicular to a main axis of said handle.

15. A snare according to any of claims 1-13, wherein said tip moves towards said first extension in response to a retraction of said first extension into said handle.

16. A snare according to any of claims 1-15, wherein said handle is plastically deformable.

17. A snare according to any of claims 1-16, wherein said handle is flexible.

18. A snare according to any of claims 1-17, wherein said handle has a diameter smaller than a coronary graft vessel.

19. A snare according to any of claims 1-18, wherein said handle has a diameter smaller than 5 mm at a distance of 4 cm from said extension.

20. A snare according to any of claims 1-19, wherein said handle has a diameter smaller than 3 nim at a distance of 4 cm from said extension.

21. A snare according to any of claims 1-20, wherein said handle has a diameter smaller than 3 mm at a distance of 10 cm from said extension.

22. A snare according to any of claims 1-21, comprising a protector adjacent said tip and configured to protect a snared vessel from damage at its end.

23. A method of mounting a graft vessel on an anastomosis delivery system, comprising: impaling said vessel on a shaφ tip adapted to cause minimal trauma to said vessel; pulling said tip and said vessel through an aperture in the side of a delivery system; and removing said vessel from said shaφ tip.

24. A method according to claim 23, comprising interfacing said tip with a surface to prevent said vessel from falling off said tip.

25. A method according to claim 24, wherein interfacing comprises elastically contacting.

26. A method according to any of claims 23-25, wherein impaling comprises placing said vessel between said shaφ tip and a surface, which tip and surface are elastically predisposed to move towards each other, with sufficient force to impale said vessel.