It has been found that in the course of various surgical procedures, it would be advantageous to enable cuts, or incisions, of specific lengths to be formed in an accurate, quick and repeatable manner. Traditionally, cuts and incisions have been made using conventional surgical instruments such as scalpels, surgical scissors, and the like. When such conventional instruments are used to form incisions, or cuts, the length of the incision, or cut, is determined by a surgeon, or medical assistant, manipulating the instrument and intuitively gauging the length of the incision, or cut, as the surgeon, or assistant, manipulates the instrument.

An example of a surgical procedure requiring an incision, or cut, to be formed, is a coronary artery bypass procedure when an anastomosis is required.

Often during such a procedure, an end of one artery, or graft, is joined to a side of another artery, or a side of one artery is joined to a side of another artery, or the like.

An arteriotomy, or incision, is then typically formed in the side of an artery so that when, for example, an end of another artery has been joined thereto, blood can flow between the arteries through the arteriotomy after the coronary artery bypass procedure has been completed.

Traditionally, such anastomosis procedures have been performed by forming the arteriotomy in the side of an artery using conventional surgical instruments, such as, a conventional surgical scissors, a scalpel, or the like, and then suturing the end of the artery to the side of another artery in conventional fashion using a suture needle carrying a length of suture. The arteriotomy should preferably be of a specific length to permit maximum blood flow therethrough without leakage at the anastomosis after completion of the procedure. Although surgeons are adept at forming arteriotomies in this fashion, it would be advantageous if the accuracy of

forming an arteriotomy of a desired length could be enhanced and if forming arteriotomies of desired lengths could be made easier.

Recently, devices have been proposed which ease the task of forming anastomoses. These devices typically place a plurality of sutures simultaneously so as to extend through an artery and another artery, or graft, which are to be joined together to form an anastomosis. By using such devices the task of suturing one artery to another artery, or graft, can be performed quicker and more accurately than conventional methods, such that when, for example, a coronary artery bypass procedure is performed using such a device, patient trauma and the integrity of joints between arteries and/or grafts is enhanced. However, it has been found that especially when such devices are used, the accuracy of the length of the arteriotomy is crucial to ensure accurate placement of the sutures and the integrity of the joints, or anastomoses. Should the incision be too long, inadequate tissue capture by the suture and/or leakage may result after the procedure has been completed. Should the incision be too short, the patency of the anastomosis may be reduced.

Accordingly, it would be advantageous if incisions of a desired length can be formed accurately, and, preferably, without reliance on a surgeons intuition.

SUMMARY OF THE INVENTION The invention provides a device and method which can be used advantageously to form incisions, or cuts, in patient tissue in an accurate and repeatable manner.

In accordance with one aspect of the invention, a cutting device for forming a cut of predetermined length in tissue is provided. The cutting device comprises two blades selectively displaceable toward each other to perform a cutting action between the blades. The cutting device further comprises a stop on at least one of the blades, the stop being positioned on the blade so that when the blade is passed into tissue the stop can be positioned to contact the tissue so that a cut of

predetermined length can be formed in the tissue when the blades are displaced toward each other to perform a cutting action while the stop contacts the tissue.

When making use of such a device, the stop is typically positioned against the tissue, such as against an edge of a vessel wall positioned adjacent an aperture in an artery wall, for example, so that when the blades are then displaced toward each other to perform a cutting action, a cut of predetermined length is formed in the tissue. The length of the cut formed in the tissue is then determined by a distance defined by the device, which distance extends from an end of the stop to an opposed position defined when the cutting device has completed a cutting action.

In accordance with another aspect of the invention, there is provided a method of forming a cut of predetermined length in tissue. The method comprises positioning at least one blade relative to tissue so that a stop on the blade contacts the tissue and actuating the blade to form a cut in the tissue, the cut having a length determined by the position of the stop on the blade.

According to yet another aspect of the invention, there is provided a cutting device for forming a cut of predetermined length in a vessel wall. The cutting device comprises two members selectively displaceable toward each other to perform a cutting action between the members. The device further comprises a stop on one of the members, the stop being positioned on the member so that when that member is passed through an aperture in a vessel wall and the stop is urged against an edge of the vessel wall adjacent the aperture, a cut of predetermined length can be formed in the vessel wall when the members are displaced toward each other to perform the cutting action while the stop is urged against the edge of the vessel wall.

In accordance with another aspect of the invention, there is provided a method of forming a cut of predetermined length in a vessel wall. The method comprises passing a distal end of a blade of a cutting device through the vessel wall, the blade having a stop. The method further comprises urging the stop against an

edge of the vessel wall and displacing the members toward each other to perform a cutting action, thereby to form a cut of predetermined length in the vessel wall.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, in which: Fig. 1 shows a schematic side view of part of a cutting device in accordance with the invention; Fig. 2 shows a schematic side view of the cutting device of Fig. 1, a blade of the cutting device being inserted through an aperture in a vessel wall; and Fig. 3 shows a schematic side view corresponding to Fig. 2 in which a stop on the blade has been urged against an edge of the vessel wall adjacent the aperture, the device being ready to perform a cutting action so as to form a cut of predetermined length in the vessel wall.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS Referring to Fig. 1 of the drawings, part of a cutting device, in accordance with the invention, for forming a cut of predetermined length in tissue, such as a vessel wall, is generally indicated by reference numeral 10.

The cutting device 10 comprises two members, or blades 12,14 which are selectively displaceable toward each other, as indicated by the double- headed arrow 16, to perform a cutting action between them. The device 10 further comprises a stop 18 on one of the blades, in this case the blade 14. Conveniently, the stop 18 protrudes laterally outwardly from the blade 14 and is defined at a step- like formation. The stop 18 is positioned on the blade 14 so that when the blade 14 is passed through an aperture in a vessel wall and the stop 18 is urged against an edge of the vessel wall adjacent the aperture, a cut of predetermined length is formed in the vessel wall when the blades are displaced toward each other to perform the cutting action, as will be described in greater detail below.

The device 10 further comprises a pivotal connection 20 connecting the blades 12,14 to each other scissors-fashion. The blades 12,14 have distal ends 12.1,14.1, respectively, remote from the pivotal connection 20. The stop 18 defines an edge, or surface 18. 1, facing in a direction extending generally along the blade 14 away from the distal end 14.1 of the blade 14 as indicated by arrow 22.

The device 10 can typically comprise arms 34,36 connected to the blades 14,12 respectively and extending from the pivotal connection 20. The arms 34,36 can then be caused to actuate the blades 12,14 so as to displace them toward each other by manually urging the arms 34,36 toward each other. Accordingly, the arms 34,36 can be provided with finger loops, or the like, at remote ends of the arms 34,36 (not shown) to enable the device to be actuated scissors-fashion.

Advantageously, the device 10 can be spring loaded, or the like, so as to urge the arms 34,36 away from each other, such that the arms are displaced toward each other against the urging of the spring to actuate the device 10.

The device 10 will now be described in use, with reference to Figures 2 and 3 of the drawings, to form a cut of predetermined length in a vessel wall.

In Figures 2 and 3, the vessel wall is indicated by reference numeral 24. Initially, a relatively small incision, or aperture 26, is made in the vessel wall 24 so that the distal end 14.1 of the blade 14 can be passed through the incision. In the case of a typical arteriotomy, the blade 14 is arranged to be passed through an incision having a length of about 2 mm. This can be achieved in conventional fashion by making use of a scalpel, or the like. The incision is typically made such that it has a length permitting a portion of the blade 14 extending from its distal end 14.1 to the stop 18 to be passed through the vessel wall 24 as indicated by arrow 28.

Instead of forming such an initial small aperture 26, the blade 14 can be provided with a distal end arranged to penetrate, or pierce, the vessel wall. Accordingly, the distal end 14.1 can be pointed, or sharp, so as to penetrate through the vessel wall 24 as it is passed therethrough in the direction of arrow 28. In such a case, pre-forming the aperture 26 using another instrument would not be necessary.

Referring now to Fig. 3, after the blade 14 has been passed through the vessel wall 24 such that the stop 18 is positioned within a vessel defined by the vessel wall, the device 10 is typically positioned such that the edge or surface 18.1 of the stop 18 abuts against, or contacts, an edge 24.1 of the vessel wall 24 adjacent the aperture 26 (Fig. 2). This can typically be achieved by urging the blade 24 in a direction extending generally along the blade 14 and away from the distal end 14.1, as indicated by arrow 30, until the stop 18 abuts against the edge 24.1.

Advantageously, the stop 18 defines a seat formation for receiving the edge 24.1 of the vessel wall 24 in seated relationship. The seat formation is typically in the form of a recess 18.2 defined by the edge, or surface 18.1. While the stop 18 abuts the edge 24.1 in this fashion, the device 10 is actuated to cause the blades 12,14 to displace toward each other about the pivotal connection 20, as indicated by arrow 16 (Fig. 1), so as to perform a cutting action thereby to form a cut of predetermined length in the vessel wall.

The length of the cut thus formed in the vessel wall 24 is determined by a distance defined by the device, which distance extends from an end of the stop, namely the edge 18.1, to an opposed position defined when the cutting device has completed a cutting action. The distance defined by the device can be a distance L extending between a bottom of the surface or edge 18.1 in the recess 18.2 and the distal end 14.1 of the blade 14, or an end of a cutting edge on the blade 14. The distance L can be about 4 mm for a typical arteriotomy. In such a case the cutting action of the device comprises displacement of the blades 12,14 toward each other such that the free end 14.1 of the blade 14 typically overlaps the blade 12 when a cutting action has been completed. Instead, an actuation stop 32 can be provided on one of the arms, such as the arm 36, so that displacement of the blades toward each other is stopped when the actuation stop abuts against the other arm 34.

Accordingly, in such a case, when the edge 24.1 of the vessel wall is received in the recess 18.2 and the blades 12,14 are displaced toward each other, a cut is formed in the vessel wall in which the cut has a length determined by a distance extending

from the bottom of the surface or edge 18. 1 in the recess 18.2 to a position at which the blades cease to overlap, which position corresponds to when the actuation stop 32 stops against the other arm 34.

Although reference is made to blades 12,14, it will be appreciated that the term"blade"is to be interpreted widely. Accordingly, the blades 12,14 need not necessarily have sharpened cutting edges, or the like, but can be arranged to perform a cut by a shearing action. The device 10 can typically be made of an appropriate material, such as surgical steel, or the like, to render it sterilizable for re- use. The arms 34,36 can be insert molded into disposable handles of an appropriate disposable material, such as, a synthetic plastics material, or the like.

Although an embodiment of the invention has been described in detail above for purposes of clarity and understanding, it will be appreciated that the invention has been described with reference to the above embodiment by way of example only, and that modifications or changes can be made without detracting from the essence of the invention. Accordingly, the scope of the invention is defined by the appended claims with due regard to equivalents of the claimed elements and features.