Surgery – Instruments – Surgical mesh – connector – clip – clamp or band
Reexamination Certificate
1999-06-18
2001-10-09
Jackson, Gary (Department: 3731)
Surgery
Instruments
Surgical mesh, connector, clip, clamp or band
C606S157000, C606S158000, C606S207000
Reexamination Certificate
active
06299621
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to surgical instruments for occluding a vessel. More particularly, the invention relates to surgical instruments such as surgical clamps and other occlusion devices, and to replaceable clamp pads for attachment to such instruments, that provide for improved atraumatic occlusion of such vessels.
Instruments for occluding blood vessels during surgery, such as conventional metal or rigid surgical clamps or clips, are well known. However, such instruments are known to cause trauma to the clamped vessel at the clamping site. A number of atraumatic instruments have been developed for reducing or eliminating the trauma to a vessel during occlusion of the vessel. U.S. Pat. No. 3,993,076 to Fogarty, et al. describes a device whereby a vessel is occluded by using a resilient tape to press a vessel against a resilient pad. However, this device suffers from the disadvantage that it slips easily and can be cumbersome to use. For example, the pulsations of an occluded artery can tend to force the device off of its clamped position on the occluded artery. Conventional surgical clamps have also been adapted to include jaw surfaces containing resilient members or pads. These devices likewise are prone to slipping off of the clamped vessel. This can be especially problematic in situations where, due to obstructions, a vessel has been clamped with only the distal tips of the clamp jaws. In such situations, the vessel can be especially prone to slipping in the direction of the distal tips.
Of particular difficulty in preventing slippage of an engaged clamp along a clamped vessel is the nature of blood vessels themselves. Blood vessels generally consist of an inner endothelial layer, an intermediate layer of smooth muscle, and an outer layer of adventitia that is composed primarily of fibrous connective tissue. The connective tissue in the adventitia itself is organized into a series of layers with the innermost layer having denser, more closely packed connective tissue and outer layers gradually becoming looser and less densely packed. These outermost layers of adventitia under sufficient force or pressure can move relative to inner vessel layers, much like the movement of an outer sleeve over an inner sleeve. As a result, a surgical clamp engaged with and contacting the outer adventitial layer can slip along the vessel by virtue of the movement of the engaged outer adventitial relative to the inner layers. With increased clamping force, such slippage can be minimized but such additional force often leads to trauma to the vessel itself.
Other attempts have been made to atraumatically occlude a vessel in a secure fashion. U.S. Pat. No. 3,746,002 to Haller describes a vascular clamp with resilient gripping members located on the jaws. A plurality of pin members are embedded within the gripping members, the pin members of a length such that when a vessel is clamped between the members, the resilient material deflects to accommodate the vessel, exposing the pin members which grippingly engage the outer layer of the vessel, thus securing the vessel to the gripping member. While the Haller device is less traumatic to a vessel than other occlusion devices, it nevertheless has the disadvantage of traumatizing the outer layer of the vessel, as the pins are rigid and non-conforming to the vessel.
U.S. Pat. No. 4,821,719 to Fogarty describes a vascular clamp device containing resilient pads with Velcro-like hooks. The hooks interact with the external adventitial layer of the vessel forming a cohesive-adhesive relationship with the vessel similar to the bonding of Velcro materials. While this device offers a less traumatic way to occlude a vessel, the cohesive-adhesive nature of the bond can result in the removal of some of the adventitial layer of the vessel when disengaging the device. Also, slippage can still occur between the engaged adventitia and the inner vessel layers. Applied Medical (Laguna Hills, Calif.) manufactures a clamp pad under the tradename A-TRAC that contains a mesh surface layered over a soft cushion.
Still other efforts have been made to provide improved clamping of vessels while resisting movement. Our own U.S. application Ser. No. 08/993,076, filed Dec. 18, 1997, describes surgical clamps with resilient filaments extending from gripping surfaces. The filaments terminate in free distal ends that abut against the engaged vessel to restrict movement relative to the filament orientation. PCT International Publication No. WO 98/33437 describes other methods of increasing the traction force applied to a clamped vessel, including the use of bristles that axially crumple to develop an occlusive force and that resist movement of the vessel relative to the instrument. The column strength of each bristle provides traction in a predetermined direction.
Despite these advances, there remains a need for a surgical clamp having clamping pads or regions which atraumatically occlude vessels while avoiding the disadvantages previously associated with existing surgical clamps or occlusion devices, including pads that miminize slippage that occurs as a result of the relative movement between outer adventitia and inner vessel layers.
SUMMARY OF THE INVENTION
The present invention meets these and other needs and provides for a pad or member that is attachable to the jaw of a jaw-type occlusion device, such as a surgical clamp or clip. The pad includes an elastomeric cushion with a woven mesh embedded in the cushion. A portion of the mesh is exposed at the clamping surface of the cushion for engagement with a clamped vessel. The mesh in this portion is itself impregnated with an elastomeric material such that a continuous sheet is formed comprised of interwoven mesh fibers encapsulated in elastomeric material. The elastomeric material spanning the fibers forms a web therebetween. The individual fibers of the mesh are themselves preferably resiliently deflectable and are generally stiffer and less easily deflected than both the elastomeric material spanning the fibers and the elastomeric cushion.
When a pad according to the invention engages a blood vessel, the configuration of the elastomer impregnated mesh allows for partial penetration of the mesh into the adventitial layers of the vessel. While not being bound by theory, we believe that as the mesh moves through the looser, outermost layers of adventitia it encounters deeper layers that are dense enough to provide resistance to further penetration by the mesh. Further advancement of the mesh compresses these layers against the inner vessel layers, thereby in essence pinning these layers against the inner layers and resisting movement of the outer adventitia relative to the inner vessel layers. However, as both the fibers and elastomeric material comprising the mesh are resiliently deflectable, the securing effect of the mesh is accomplished with the minimum of trauma to the adventitia and underlying vessel tissue.
In addition, the characteristics of the cushion and the embedded mesh are such that the cushion and mesh work together to achieve a synergistic effect. The portion of the cushion containing the embedded mesh forms a clamping region of the cushion. The embedded mesh provides structural support to the clamping region by reinforcing and stabilizing the region against deformation, especially lateral deformation, when the pad is under a clamping load. The clamping region in turn stabilizes and orients the mesh at the desired angle relative to the cushion surface. The clamping region performs this orientation function prior to and during the application of a clamping load to the pad. When a load is applied to the pad, the mesh and the cushion are deflected, but the clamping region stabilizes the mesh against excessive deformation and maintains the desired orientation of the mesh. The clamping region continues to perform this function as the load is released from the pad and the deflected mesh and cushion return to their original pre-loaded positions.
Methods of manufacturing the att
Fogarty Thomas J.
Hermann George D.
Howell Thomas A.
Whittemore Joshua S.
Jackson Gary
Morrison & Foerster / LLP
Novare Surgical Systems, Inc.
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