Medical instrument positioning device internal to a catheter...

Surgery – Instruments – Means for inserting or removing conduit within body

Reexamination Certificate

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Reexamination Certificate

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06214016

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an improved medical positioning device for the precise positioning of a medical treatment instrument into an interior organ. The invention additionally contemplates a related method of using the present invention. The present medical positioning device penetrates selected tissue to precisely position a medical treatment instrument into an interior organ while minimizing trauma to tissue surrounding the treatment site. By minimizing trauma to surrounding tissue, the medical positioning device allows for greater medical benefits while minimizing side effects. This invention is particularly useful for guiding and positioning a catheter or an electrical stimulation lead into the brain along a non-linear insertion path.
2. Description of the Related Art
In many medical procedures, it is necessary to position a catheter or an electrical stimulation lead at a precise location within a patient's body. Often, precise placement of a medical treatment instrument is difficult because of the location of the treatment site in the body. These difficult treatment sites may be nearby critical body organs, nerves, or other components that are at high risk of being damaged while the instrument is moved to the treatment site.
The placement of catheters and leads into the body, and particularly into the brain, has been primarily in a straight, linear manner. To place the catheter or lead straight into the brain, a straight, solid metal wire, called a stylet, is used. For many potential treatment sites, a straight insertion of a catheter using a wire stylet has drawbacks that prevent the optimal placement of a medical treatment instrument. For example, the straight insertion of an instrument into some portions of the brain would pass through other critical brain areas, which control a patient's sensory or bodily functions, thereby possibly causing damage to a patient's speech, hearing, or sight. For other portions of the brain, a linear insertion route would require insertion through other undesirable locations that would cause increased trauma to the patient. Ideally, a surgeon wishes to guide a catheter or lead into the brain while avoiding these critical brain areas. To avoid these critical brain areas, it has been found to be desirable to insert the medical treatment instrument into the brain along a curved or nonlinear path, so as to allow a surgeon to precisely place a catheter or stimulation lead into the brain on an insertion path that avoids damage to critical brain tissue.
A number of prior art positioning devices exist that allow for the non-linear placement of a catheter or lead into the body. For example, U.S. Pat. No. 5,195,968 to Lundquist shows a catheter steering mechanism utilizing a pull wire type guiding system. Pull wire type guiding systems have been used primarily to place a catheter into the heart by way of coronary veins. Also, U.S. Pat. No. 4,873,983 to Winters, U.S. Pat. No. 4,917,102 to Miller et al, and U.S. Pat. No. 5,308,324 to Hammerslag et al, show flexible movable core guide wires. Flexible movable core guide wires have been primarily used to insert a catheter through the coronary arteries.
The placement of medical treatment instruments into interior organs presents an additional challenge that makes prior art positioning devices less suitable for use in solid, soft tissue interior organs, such as the brain. Known prior art devices have been used primarily in open cavities that are hollow or filled only with a liquid such as blood. Because open cavities are essentially hollow, a surgeon may move a medical positioning device from side to side within the hollow cavity without damaging tissue by the device's side to side movement. In a solid interior organ, like the brain, however, side to side movement would cause sensitive tissue to be damaged or even sliced.
If a surgeon used a pull wire guiding system or a movable core guide wire system to insert a catheter or lead into the brain, it would damage or slice brain tissue. Additionally, movable core guide wires may be excessively flexible and not strong enough to be effectively used for inserting a treatment instrument into and through brain tissue. Because of these drawbacks, surgeons have typically not used pull wire guiding systems or movable core guide wire systems for placing medical treatment instruments into the brain. Instead, brain surgeons have generally used straight stylets for the straight, linear insertion of a medical treatment device into the brain. Thus, there is a need for a medical positioning device that will allow for the precise placement of medical treatment devices into soft tissue interior organs along a curved path with minimal or non-existent, critical lateral or slicing movement.
The present invention is an improved medical positioning device which allows the user to precisely position a catheter or lead into the brain following a non-linear or curved insertion path while minimizing or even eliminating unwanted damage to surrounding brain tissue and trauma to a patient.
SUMMARY OF THE INVENTION
The present medical positioning device allows a catheter, a lead, or other medical treatment instrument to be precisely placed into an interior organ along a curved, nonlinear path. The present invention is particularly suitable for use in the brain. The present invention allows a surgeon to guide a catheter or lead to a specific treatment site into an interior organ following a predetermined nonlinear insertion path designed to avoid critical structures within the organ. The present invention additionally allows for the precise placement of a treatment device along a non-linear or curved insertion path with minimal damage to tissue surrounding the targeted treatment site.
In summary, the present positioning device comprises, in combination, a substantially rigid outer tubular member, an elastically deformable inner tubular member having a curvature, and an innermost member. The elastically deformable inner tubular member is placed inside the outer tubular member and is slidably movable within the outer tubular member. Because the inner tubular member is elastically deformable, the curved portion of the inner tubular member temporarily straightens when it is placed substantially inside the outer tubular member. The superelastic property of the inner tubular member allows it to elastically return to its original curvature when it passes outwardly through the outer tubular member and into bodily tissue. The innermost member is placed inside the inner tubular member and is slidably movable within the inner tubular member. Once the three components are assembled, they are placed within a medical treatment device such as a catheter or lead. Alternatively, the medical treatment instrument is placed within the outer tubular member. In this configuration, the superelastic inner tubular member and the innermost member are slidably movable within the medical treatment instrument.
In operation, a surgeon inserts the outer tubular member into the body until it penetrates a selected organ to a predetermined depth near the treatment site. Once the outer tubular member has been inserted to the proper depth, the surgeon fixes the position of the outer tubular member. The surgeon then advances the elastically deformable inner tubular member out the end of the outer tubular member to bring it closer to the treatment site. When exiting the outer tubular member, the inner tubular member elastically resumes its curvature and advances outwardly along a curved path into and through the organ. Once the superelastic inner tubular member has been advanced to its desired location, the surgeon fixes its position. Next, the surgeon advances the innermost member out the end of the inner tubular member until it reaches the treatment site. As each of the three components is inserted into the body, the medical treatment instrument is also advanced. Thus, the advancement of the innermost member brings the treatment instrument to the t

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