Vascular conduit and delivery system for open surgical placement

The present patent document claims the benefit of the filing date under 35 U.S.C. §119(e) of Provisional U.S. Patent Application Ser. No. 60/982,868, filed Oct. 26, 2007, which is hereby incorporated by reference, and Provisional U.S. Patent Application Ser. No. 61/127,308, filed May 12, 2008, which is hereby incorporated by reference.

1. Technical Field

The present invention relates generally to a device for repair of body vessels. More particularly, the invention relates to a vascular conduit for repair of a damaged artery or vein during an emergency open surgical procedure.

2. Background Information

Emergency physicians frequently encounter patients having traumatic injury to a body vessel. Significant damage to a body vessel, such as a blood vessel, may expose a patient to deleterious conditions such as the loss of a limb, loss of function of a limb, increased risk of stroke, impairment of neurological functions, and compartment syndrome, among others. Particularly severe cases of vascular injury and blood loss may result in death. In such severe situations, the immediate goal is to obtain hemostasis while maintaining perfusion. Examples of treatments that are commonly performed by emergency physicians to treat vessel injury secondary to trauma include clamping the vessel with a hemostat, use of a balloon tamponade, ligation of the damaged vessel at or near the site of injury, or the insertion of one or more temporary shunts.

In the case of traumatic injury to blood vessels, the use of temporary shunts has been linked to the formation of clots. Shunts are generally placed as a temporary measure to restore blood flow, and to stop excessive blood loss. This may require returning the patient to the operating room for treatment and removal of the clots, often within about 36 to 48 hours of the original repair. When the patient has stabilized (generally a few days later), the shunt is typically removed and replaced with a vascular graft, such as a fabric graft that is sewn into place. Ligation of the damaged blood vessel may result in muscle necrosis, loss of muscle function, edema, or compartment syndrome with potential limb loss or death.

Due to the nature of the vascular injury that may be encountered, the use of shunts, repairing and/or ligating of a blood vessel often requires that such treatments be performed at great speed, and with a high degree of physician skill. Such treatments may occupy an undue amount of the time and attention of an emergency physician at a time when other pressing issues regarding the patient\'s treatment may also require immediate attention. In addition, since the level of particularized skill required may exceed that possessed by the typical emergency physician, particularly traumatic episodes may require the skills of a physician specially trained to address the particular trauma, such as a vascular trauma, and to stabilize the patient in the best manner possible under the circumstances of the case.

U.S. Patent Publication No. 2007/0027526 A1, incorporated by reference herein, discloses a device for repair of damaged portions of a body vessel. The device depicted in the patent publication includes a cylindrical body 12, having a fitting 14 disposed at either or both axial ends of the cylindrical body. This device is suitable for placement within a body vessel, such as a blood vessel, for repair of vascular trauma and restoration of fluid flow through the vessel. In the embodiment depicted in FIG. 3A of the patent publication, the fitting comprises an elongated tubular structure having a recessed portion 16 adjacent each axial end of a main fitting body portion 15, which may be compressed to secure the graft to the fitting. Alternatively, the graft can be secured by a slidable cuff received by a feature within the ring. One end of the fitting is snugly received within the lumen of the cylindrical body, and one or more sutures 18 are tied around the circumference of the cylindrical body to secure the fitting firmly to the cylindrical body. When the device is positioned in the vessel undergoing repair, one or more sutures 20 are tied around the vessel at an exposed portion of the fitting, as shown in FIG. 5, to secure the vessel to the fitting. The device depicted in the 2007/0027526 A1 publication is believed to be effective in repairing damaged vessels utilizing open surgical techniques in an emergency situation. However, since the device utilizes sutures to affix the damaged tissue portions to the fitting, the physician must take time to tie the sutures properly. Although in modern medicine sutures can be tied in relatively rapid fashion, any step in a repair process that occupies physician time in an emergency situation is potentially problematic. Therefore, efforts continue to develop techniques that reduce the physician time required for such techniques, so that this time can be spent on other potentially life-saving measures.

In addition to the foregoing, the use of sutures to affix the vessel to the fitting compresses the tissue of the vessel against the fitting. Compression of this tissue may result in necrosis of the portion of the vessel tissue on the side of the suture remote from the blood supply. Necrosis of this portion of the vessel tissue may result in the tissue separating at the point of the sutures. In this event, the connection between the vessel and the fitting may become weakened and subject to failure. If the connection fails, the device may disengage from the vessel.

U.S. Patent Publication No. 2005/0038502 A1, filed Apr. 21, 2004, describes a docking head that is mounted on a graft having an outer diameter so as to couple the graft to a blood vessel without requiring the use of sutures. The docking head includes a hollow truncated cone having a passage that is adapted to correspond to the outer diameter of a graft and a plurality of outwardly pointing and inclined barbs. The barbs may be flexible and inclined opposite a truncated end of the hollow truncated cone and are 1 to 4 times the thickness of the wall of the blood vessel. The inclined barbs are arranged at the circumference of the conical structure in at least one row and are distally pointed to the direction of the graft\'s body. In operation, the conical structure followed by the graft is inserted into neck through its narrow end while inclined barbs smoothly pass through a portion of the neck. Upon pulling back the conical structure, inclined barbs are embedded within the neck, forming a firm and sealed connection between the vessel and the graft.

While the outward facing barbs may facilitate secure placement of graft by securing the truncated cone portion within a body vessel, the particular design of the outward facing barbs presents drawbacks. First, these inclined barbs extending from the outer surface of the docking head, for example as shown in FIGS. 14 and 15, may engage body tissue away from the intended point of treatment during placement of the device. The tendency of the barbs pointing outwardly to engage tissue or other surfaces inadvertently can present a challenge during emplacement of the graft. Second, once in place within a body vessel, these barbs are not sized to penetrate an optimal distance into the wall of the body vessel. For example, FIG. 19 shows barbs 404 penetrating through the entire wall of a body vessel, which can lead to undesirable complications, such as bleeding and/or thrombus formation.

Thus, it would be desirable to provide a conduit for use in repair of a body vessel, such as an artery or a vein, and/or a delivery system, during emergency surgery in a manner that is time effective, that addresses the trauma at hand to the extent possible, and that utilizes techniques that may be readily practiced by an emergency physician. In addition, it would be desirable if the conduit utilized during emergency surgery is permanently placed within the patient, thereby obviating a need for subsequent surgical intervention. It is also desirable to provide a medical device having inclined barbs that are shielded from inadvertent contact with body tissue by a delivery system during the delivery process, and/or barbs adapted to penetrate only a portion of the wall of the body vessel required to secure the medical device within the body vessel.

In a first embodiment, a device for intraoperative repair of a damaged portion of a body vessel is provided. The device can be a vascular conduit for use in repair of the body vessel, such as an artery or a vein, during emergency surgery in a manner that is time effective, that addresses the trauma at hand to the extent possible, and that utilizes techniques that may be readily practiced by an emergency physician. The device utilized during emergency surgery can be permanently placed within the patient, thereby obviating a need for subsequent surgical intervention. Since the body vessel has a vessel wall including a tunica intima, a tunica media, and a tunica adventitia, the device controllably interacts with the tunica intima, basement membrane, and tunica media, and avoids any interaction with the tunica adventitia to not disrupt the vasa vasorum residing in the tunica adventitia. The device is preferably secured in a rapid manner without the use of a ligature or suture placed around the vessel, which may cause distal necrosis.

In one aspect, the device includes a tubular conduit having a wall defining a lumen about a longitudinal axis between a first axial end and a second axial end. The tubular conduit may include a flexible biocompatible material, such as expanded polytetrafluoroethylene, silicone, polyurethane, polyamide, or the like. The device also includes a first connector and a second connector disposed at the respective first and second axial ends of the tubular conduit. The first and second connectors can have a first portion engageable with the wall of the tubular conduit and a second portion having at least one shaped member extending radially therefrom. The shaped member can include barbs, fibers, bristles, or outer protruding and penetrable media. The shaped member can be dimensioned and arranged along the second portion to penetrate and anchor into the tunica intima and tunica media of the vessel wall upon insertion of the device into the body vessel. In one example of the device, the first portion of at least one of the first and second connectors has at least one shaped member, where the shaped member of the first portion is penetrable and anchorable into wall of the tubular conduit.

In another aspect of the device, the shaped member of the second portion and/or the first portion of the first and second connectors includes a plurality of microbarbs. The microbarbs can be spaced along a circumference of the second and/or first portion, and can be aligned at an acute angle relative to the longitudinal axis. In one example, the microbarb is aligned at an acute angle of about 5 degrees to about 30 degrees, and most preferably about 20 degrees to about 25 degrees, relative to the longitudinal axis. The microbarb can include a body having a first and second edge converging to form a tip region. A portion of the body of the microbarb outside the tip region may have a dullness configured to not cut or lacerate the body vessel radially when the microbarb is engaged. The tip region that can have a surface generally parallel relative to the longitudinal axis, and the surface may also be arcuate. The microbarbs can be arranged to be spaced along the circumference of the tubular body to form at least one ring of microbarbs. The microbarbs can be at various acute angles relative to the longitudinal axis, have various quantities along the circumference, various sizes, and/or a substantially parallel surface relative to the longitudinal axis.

In a second embodiment, a delivery system for deploying a tubular medical device in a body vessel. In one aspect, the delivery system can include an elongated tubular member that has a lumen about a longitudinal axis and a proximal end and a distal end. The elongated tubular member can be sized to extend through the lumen of the tubular medical device. A handle can be attached to the proximal end of the elongated tubular member. The handle has a lumen about the longitudinal axis and a proximal end and a distal end. The lumen of the handle is in communication with the lumen of the elongated tubular member. A dilator tip is disposed at the distal end of the elongated tubular member. The dilator tip can be sized and configured to receive the distal end of the elongated tubular member and to engage the distal end of the tubular medical device. The delivery may further include a controller disposed at the handle, which manipulates the dilator tip. The controller includes a control member extending through the lumens of the respective elongated tubular member and the handle. The control member can have a distal end attached to the dilator tip and a proximal end attached to the controller. The controller can be configured to retract the dilator tip in a proximal direction to a retracted position and to extend the dilator tip in a distal direction to an extended position.

In another aspect of the delivery system, the dilator tip has a conical shape tapering from a blunt distal end to a proximal end. The dilator tip preferably includes a cavity with a proximal region that can be sized and configured to receive the distal end of the elongated tubular member and to engage the distal end of the tubular medical device. In one example, the proximal region of the dilator tip may be configured to expand radially between a first cross-sectional area and a second cross-sectional area greater than the first cross-sectional area. The first cross-sectional area is less than a cross-sectional area of the lumen of the tubular medical device, while the second cross-sectional area is greater than the cross-sectional area of the lumen of the tubular medical device. In another example, the proximal region of the dilator tip can be configured to enclose partially the distal end of the tubular medical device when in the retracted position. The proximal region of the dilator tip may be configured to engage to the distal end of tubular medical device, or optionally, the proximal region may be configured to apply a radially compressive force to the distal end of the tubular medical device, when the dilator tip is in the retracted position, such that the tubular medical device can be retained in a fixed position. When the tubular medical device includes a shaped member, such as a plurality of microbarbs that are spaced along a circumference at the distal end of the tubular medical device, the proximal region of the dilator tip can be configured to enclose partially the microbarbs of the tubular medical device to protect the body vessel during deployment.

In yet another aspect of the delivery system, the controller is movable between a first position to retract the dilator tip to the retracted position and a second position to extend the dilator tip to the extended position. The controller may also include a spring mechanism disposed within the lumen of the handle. The spring mechanism can be biased to an expanded configuration to retain the controller at the first position and being moveable to a compressed configuration to move the controller to the second position. The controller can also include a lockable switch that is movable between a first position to allow the controller to move between the first and second positions and a second position to fix the controller at the second position.