Flexible tip medical instrument

Details Flexible tip medical instrument Flexible tip medical instrument

2000-11-28

2002-07-16

Shaver, Kevin (Department: 3736)

Surgery

Diagnostic testing

Sampling nonliquid body material

C600S567000, C606S167000, C604S164010

Reexamination Certificate

active

06419641

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to biopsy systems. Specifically, the invention concerns devices for obtaining biopsy samples through veins and arteries.
BACKGROUND OF THE INVENTION
In the practice of diagnostic medicine, it is often necessary or desirable to perform a biopsy, or to sample selected tissue from a living patient for medical evaluation. Cytological and histological studies of the biopsy sample can then be performed as an aid to the diagnosis and treatment of disease. Biopsies can be useful in diagnosing and treating various forms of cancer, as well as other diseases in which a localized area of affected tissue can be identified.
During the biopsy procedure, care is taken to minimize the physical trauma inflicted upon the intervening tissues that surround the affected area or target tissue and at the same time to protect the practitioner from health hazards. One typical biopsy procedure includes inserting a hollow biopsy needle through the intervening tissue into the target tissue to be sampled. The sample tissue is then harvested through the needle by applying suction through the needle, typically with a syringe.
Special considerations apply if the biopsy is to be performed on an internal organ deep within the body such as the liver. Previously, obtaining a tissue sample from an internal organ, such as the liver, was carried out percutaneously by entering the skin in the vicinity of the organ and thereafter extracting a core of liver material through the biopsy needle. This method, although effective in obtaining an adequate amount of tissue from the liver, is no longer acceptable practice, since it is not uncommon for the patient to suffer from serious health complications caused by the biopsy. For example, patients generally experience extreme pain, and additionally, the liver profusely bleeds after percutaneous biopsy. Moreover, liver biopsies are typically performed on patients having liver disease, liver transplants and coagulation disorders, and such conditions further complicate percutaneous liver biopsies.
Alternatively, tissue samples may be obtained without the problems associated with percutaneous biopsy by accessing the liver via a transjugular procedure. Known techniques involve accessing the liver through the jugular vein with an elongated biopsy device. Typically, these biopsy devices are identical to typical single and double action biopsy devices except that the inner and outer needles are elongated to access the liver from the jugular vein.
An example of a typical transjugular single action biopsy device
20
is shown in
FIGS. 1-3
. Biopsy device
20
includes an outer hollow needle
22
defining a lumen
24
therethrough. An inner needle
26
is slidingly engaged inside lumen
24
and is moveable relative to outer needle
22
. The inner needle
26
defines a first or distal end
28
having a tissue cutting point
30
and a cavity
32
adjacent first end
28
for receiving tissue samples. The inner needle
26
is slidable relative to outer needle
22
between a first retracted position (
FIG. 3
) and a second extended position (FIG.
2
). In the first retracted position, inner needle
26
is retracted within lumen
22
so that outer needle
22
covers cavity
32
so that the distal end can be inserted into the liver. In the second extended position, the first end
28
of inner needle
26
is extended away from outer needle
22
to expose cavity
32
to tissues at the biopsy site. Such means are known in the art and commercially available. For example, biopsy devices of this type are available form U.S. Biopsy, Inc., a division of Promex, Inc., 3049 Hudson Street, Franklin, Ind., (317) 736-0128.
During a transjugular liver biopsy an elongated introducer
34
, as illustrated in
FIG. 4
, is inserted through a small incision or puncture made in the skin. The introducer
34
is an elongated, small diameter cannula defining a lumen
36
that receives and guides the distal end
35
of biopsy device
20
to the biopsy site. A tip
38
of the introducer
34
is carefully advanced through venous passageways with the assistance of X-ray or fluoroscopy. Great care is taken to position the tip
38
at the precise location of the intended biopsy site. The biopsy device
20
is then advanced through the introducer lumen
36
and thereafter tissue cutting point
30
of inner needle
26
enters the liver tissue. During this insertion stage of the procedure, inner needle
26
is positioned within outer needle
22
in the first, retracted position (FIG.
3
).
Once device
20
has been positioned at the targeted site for the biopsy, inner needle
26
is momentarily driven into liver tissue far enough to expose cavity
32
of inner needle
26
. Liver tissue then prolapses into cavity
32
. The device is then fired to advance outer needle
22
along inner needle
26
to cover cavity
32
. This forward movement of outer needle
22
severs the prolapsed tissue to obtain a tissue sample, which becomes trapped in cavity
32
of inner needle
26
. Movement of inner and outer needles
26
,
22
to capture a sample occur almost instantaneously via firing mechanism
27
engaged with proximal ends
29
of needles
26
,
22
. The quality of the sample is largely dependent on the thrust or “strike” of outer needle
22
securing the tissue since the tissue is often parenchymatous tissue and is gelatinous in consistency. With outer needle
22
blocking the opening of cavity
32
, biopsy assembly
20
may then be withdrawn, carefully backing out of introducer
34
leaving the introducer in place. Biopsy device
20
is then withdrawn from the target site carrying the sample within cavity
32
. To collect the biopsy sample outer needle
22
is once again retracted to expose cavity
32
of inner needle
26
. Typically, the biopsy device is re-inserted into the introducer to collect another biopsy sample. The procedure may be repeated several more times until satisfactory samples have been obtained.
A problem associated with this type of biopsy device is that the rigid inner and outer needles
26
,
22
are metallic, commonly stainless steel, and lack the flexibility to freely move within the introducer
34
due to the significant curve
42
located at the introducer's distal end
44
(FIG.
4
). The curve
42
of the introducer
34
causes the inner and outer needle
26
,
22
to bind with an inner wall
46
comprising lumen
36
of the introducer
34
, which in turn, can cause movement of the introducer. Consequently, the introducer is prone to movement due to the formation of resistance between inner and outer needles
26
,
22
traversing curve
42
in introducer
34
. Movement of the introducer once it is ideally placed is undesirable since damage to the surrounding tissue and poor biopsy samples are frequently the result of such movement. Moreover, since the curve
42
in the introducer causes continuous binding, even after the outer needle
22
has cleared the curve
42
, much of the momentum imparted on inner and outer needles
26
,
22
via spring force of firing mechanism
27
is utilized to overcome this binding or frictional force. Consequently, the effectiveness of the firing mechanism
27
is diminished resulting in recovery of small and fractured tissue specimens. Moreover, repeatedly firing the biopsy device
20
during subsequent sampling events causes the sliding surfaces of the outer needle
22
and inner wall
46
of introducer
34
to become “galled” i.e., deformation of the sliding surfaces, resulting in an additional and significant decrease in performance of the firing mechanism
27
. As a result, little if any tissue is recovered and the device
20
may be permanently damaged before an adequate specimen is captured. The damaged device is then discarded and additional devices must then be used to capture adequate and sufficient tissue. This is unfortunately common and leads to a significant and unwarranted cost increase due to equipment, personnel and room charges, as well as an extended biopsy procedure for the patient.
Bi

Affiliated with

Also associated with

Rating

Flexible tip medical instrument does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Flexible tip medical instrument, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Flexible tip medical instrument will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2915029