U.S. patent application number 12/765626 was filed with the patent office on 2013-04-25 for medical retrieval device.
This patent application is currently assigned to Boston Scientific Scimed, Inc.. The applicant listed for this patent is Jason W. Kear, Justin Reppert. Invention is credited to Jason W. Kear, Justin Reppert.
Application Number | 20130103045 12/765626 |
Document ID | / |
Family ID | 32092816 |
Filed Date | 2013-04-25 |
United States Patent
Application |
20130103045 |
Kind Code |
A9 |
Kear; Jason W. ; et
al. |
April 25, 2013 |
MEDICAL RETRIEVAL DEVICE
Abstract
A medical retrieval device has a multi-prong retrieval assembly.
The multi-prong retrieval assembly has a first position, in which
the retrieval assembly extends from the distal end of the sheath to
form an open ended grasping device, and a second position, in which
the retrieval assembly extends from the distal end of the sheath to
form a substantially close ended basket-type retrieval device. When
the retrieval assembly is used as a basket-type retrieval device,
the distal ends of the prongs of the retrieval assembly that form
the basket are not connected to each other. Thus, captured objects
may be released by the operator, or by applying sufficient force to
separate one or more of the prongs.
Inventors: |
Kear; Jason W.;
(Bloomington, IN) ; Reppert; Justin; (Spencer,
IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kear; Jason W.
Reppert; Justin |
Bloomington
Spencer |
IN
IN |
US
US |
|
|
Assignee: |
Boston Scientific Scimed,
Inc.
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20100204711 A1 |
August 12, 2010 |
|
|
Family ID: |
32092816 |
Appl. No.: |
12/765626 |
Filed: |
April 22, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11730527 |
Apr 2, 2007 |
7731723 |
|
|
12765626 |
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|
10273513 |
Oct 18, 2002 |
7211089 |
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11730527 |
|
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Current U.S.
Class: |
606/127 |
Current CPC
Class: |
A61B 2017/2212 20130101;
A61B 17/221 20130101 |
Class at
Publication: |
606/127 |
International
Class: |
A61B 17/221 20060101
A61B017/221 |
Claims
1. A medical retrieval device, comprising: a sheath including a
distal end; and a multi-prong retrieval assembly having a collapsed
position within the sheath, a first position, in which the
multi-prong retrieval assembly extends from the distal end of the
sheath to form an open ended grasping device, and a second
position, in which the multi-prong retrieval assembly extends from
the distal end of the sheath to form a substantially close ended
basket-type retrieval device.
2-24. (canceled)
Description
TECHNICAL FIELD
[0001] The invention generally relates to medical devices for
retrieving material from within a body. More particularly, the
invention relates to a medical retrieval device that combines the
functions of grasper-type retrieval devices and basket-type
retrieval devices.
BACKGROUND
[0002] Blockages or obstructions, such as stones or calculi can
develop in certain parts of the body, including the kidneys,
pancreas, esophagus, and gallbladder. Minimally invasive surgical
procedures, typically involving percutaneous insertion of a
retrieval device through an endoscope or laparoscope, may be used
to break up and remove such blockages. For example, currently
available medical retrieval devices provide physicians with the
ability to retrieve stones that are in easily accessible areas of
the urinary tract.
[0003] One type of retrieval device, known as a "basket" retrieval
device, typically is formed of a wire assembly that surrounds a
captured stone or calculi during retrieval. Many known basket-type
devices collapse into the distal end of a catheter during
insertion, and are extended from the end of the catheter when
deployed. Basket-type retrieval devices typically require a
physician to advance the device past the stone mass, deploy the
retrieval device, and then pull it back toward the stone to capture
the stone.
[0004] Difficulties can arise when using such a basket device when,
for example, a stone becomes stuck or wedged during removal. In
such a situation, damage to surrounding tissue or tissue lining may
result if the physician forces the basket and stone through an area
in which the stone has become stuck or wedged. To avoid such
damage, it may be necessary to release the stone and break it into
smaller fragments. Unfortunately, typical basket retrieval devices
do not allow the physician to release easily the stone and continue
breaking it up before removal is again attempted.
[0005] To address these difficulties, stone removal can be
accomplished using a grasper, instead of a basket device.
Typically, a grasper is a device having three or four prongs that
are manipulated to capture a stone from the front side of the
stone, by grasping it. When a stone becomes stuck or wedged during
removal, such graspers are able to release the stone.
Unfortunately, graspers typically do not hold on to stones as well
as baskets. It may be difficult to capture a stone using a grasper,
and once captured, it is easy for the stone to be released
inadvertently.
[0006] Over the course of a procedure, a physician may need to use
both graspers and basket-type devices to manipulate a stone, break
up the stone, and remove fragments of the stone. Using current
graspers and baskets, a physician may need to switch devices during
the procedure. Switching devices typically requires withdrawal of
one device and insertion of another.
SUMMARY OF THE INVENTION
[0007] The invention generally relates to a single medical
retrieval device that can function as both a grasper and a
basket-type retrieval device. A combined grasper and basket device
according to the invention can easily grasp, release, and transport
stones or other calculi.
[0008] In one aspect, the invention involves a medical retrieval
device that comprises a sheath and a multi-prong retrieval
assembly. The multi-prong retrieval assembly has a first position,
in which the multi-prong retrieval assembly extends from a distal
end of the sheath to form an open ended grasping device, and a
second position, in which the multi-prong retrieval assembly
extends from the distal end of the sheath to form a substantially
close ended basket-type retrieval device.
[0009] In one embodiment, the open-ended grasping device is adapted
to capture material by grasping a front portion of the material.
The substantially close-ended basket-type retrieval assembly is
adapted to capture material by enclosing the material within the
basket-type retrieval device.
[0010] In one embodiment, a portion of the multi-prong retrieval
assembly is exposed to form the open ended grasping device when the
multi-prong retrieval assembly is in the first position.
Substantially the entire multi-prong retrieval assembly is exposed
to form the substantially close ended basket-type retrieval device
when the multi-prong retrieval assembly is in the
second-position.
[0011] In one embodiment, a prong of the multi-prong retrieval
assembly has a barbed tip. The barbed tip may be oriented to face a
central, or longitudinal axis of the retrieval assembly when the
retrieval assembly is in the first position.
[0012] In one embodiment, a prong of the multi-prong retrieval
assembly has a rolled tip.
[0013] In one embodiment, one or more teeth are disposed on a
distal portion of the multi prong retrieval assembly that extends
from the sheath when the retrieval assembly is in the first
position. These teeth may be oriented to face a central or
longitudinal axis of the retrieval assembly when the retrieval
assembly is in the first position.
[0014] In one embodiment, one or more prongs of the multi-prong
retrieval assembly are deformable, such that the distal ends of the
prongs may separate from each other to release a captured object
when the retrieval assembly is in the second position and a
predetermined force is applied to the prongs.
[0015] In one embodiment, the medical retrieval device may be
actuated to cause the prongs of the multi-prong retrieval assembly
to separate from each other when the retrieval assembly is in the
second position.
[0016] Certain embodiments of the medical retrieval device include
a retrieval assembly having either three or four prongs, though
other embodiments may include a greater number of prongs.
Generally, a prong of the retrieval assembly may be composed of
nitinol, stainless steel, a Co--Cr alloy, or a titanium alloy,
though other materials also may be used.
[0017] In another aspect of the invention, in use, a portion of the
medical retrieval device is inserted into a body tract while the
multi-prong retrieval assembly is in a collapsed position within
the sheath. The multi-prong retrieval assembly is then placed in a
position in which it extends from the distal end of the sheath, and
maneuvered to capture material. Once the material is captured, the
medical retrieval device, along with the material are withdrawn
from the body.
[0018] The multi-prong retrieval assembly may be placed in a first
position, permitting the device to be used as a grasper, for
grasping material similar to forceps. The multi-prong retrieval
assembly also may be placed in a second position, permitting the
device to be used as a basket-type retrieval device to capture
material within a basket formed by the prongs of the multi-prong
retrieval assembly. If necessary, the material may be released from
the device by applying force to one or more of the prongs or the
multi-prong retrieval assembly. Material may also be released by
actuating the medical retrieval device to open the multi-prong
retrieval assembly.
[0019] In another aspect of the present invention, a multi-position
medical retrieval device may be deployed by placing a multi-prong
retrieval assembly in a first position, in which the multi-prong
retrieval assembly extends from a distal end of a sheath to form an
open ended grasping device, and by placing the multi-prong
retrieval assembly in a second position, in which the multi-prong
retrieval assembly extends from the distal end of the sheath to
form a substantially close-ended basket-type retrieval device. The
multi-prong retrieval assembly may also be placed into a collapsed
position within the distal end of the sheath.
[0020] In one embodiment, deploying the multi-position medical
retrieval device further comprises actuating the multi-position
medical retrieval device when the multi-prong retrieval assembly is
in the first position to open or close the open ended grasping
device formed by the multi-prong retrieval assembly.
[0021] In one embodiment, deploying the multi-position medical
retrieval device further comprises actuating the multi-position
medical retrieval device when the multi-prong retrieval assembly is
in the second position to open the substantially close-ended
basket-type retrieval device formed by the multi-prong retrieval
assembly.
[0022] These and other objects, advantages, and features of the
invention will become apparent through reference to the following
description, the accompanying drawings, and the claims.
Furthermore, it is to be understood that the features of the
various embodiments described herein are not mutually exclusive and
can exist in various combinations and permutations.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] In the drawings, like reference characters generally refer
to the same parts throughout the different views. The drawings are
not necessarily to scale, emphasis instead generally being placed
upon illustrating the principles of the invention. In the following
description, various embodiments of the present invention are
described with reference to the following drawings, in which:
[0024] FIGS. 1A-B show illustrative embodiments of a medical
retrieval device constructed in accordance with the invention;
[0025] FIGS. 2A-C show an embodiment of a retrieval assembly in
accordance with the invention in a collapsed position, a first
position, and a second position, respectively;
[0026] FIGS. 3A-C show a second embodiment of a retrieval assembly
in accordance with the invention in a collapsed position, a first
position, and a second position, respectively;
[0027] FIGS. 4A-B show an embodiment of a retrieval assembly in
accordance with the invention, wherein distal portions of prongs of
the retrieval assembly include a series of teeth;
[0028] FIGS. 5A-B show an embodiment of a retrieval assembly in
accordance with the invention, wherein prongs of the retrieval
assembly have rolled tips;
[0029] FIGS. 6A-D illustrate a method of using a medical retrieval
device in accordance with the invention as a grasper;
[0030] FIGS. 7A-C illustrate a method of using a medical retrieval
device in accordance with the invention as a basket-type retrieval
device; and
[0031] FIGS. 8A-B illustrate the release of material from a medical
device in accordance with the invention when a stricture through
which the material is unable to pass is encountered.
DESCRIPTION
[0032] FIG. 1A shows a view of a medical retrieval device 100 in
accordance with an illustrative embodiment of the present
invention. The medical retrieval device 100 includes a sheath 102,
a retrieval assembly 104, disposed at a distal end 112 of the
sheath 102, and a handle 106, disposed at a proximal end 114 of the
sheath 102. As shown in FIG. 1A, the retrieval assembly 104 is in
an extended position, in which the retrieval assembly 104 extends
from the distal end 112 of the sheath 102. The retrieval assembly
104 may be placed in this extended position either by pushing the
retrieval assembly 104 out of the distal end 112 of the sheath 102,
or by retracting the distal end 112 of the sheath 102 to expose a
portion of the retrieval assembly 104.
[0033] An elongated member 108 extends within the sheath 102 from
an actuating mechanism 110 on the handle 106 to the retrieval
assembly 104. Operation of the actuating mechanism 110 can move the
elongated member 108 to cause the retrieval assembly 104 to be
placed in a collapsed position within the sheath 102, or to extend
from the distal end 112 of the sheath 102 into a first position, in
which the retrieval assembly 104 is used as a grasper, or into a
second position, in which the retrieval assembly 104 is used as a
basket-type retrieval device.
[0034] Alternatively, as shown in FIG. 1B, the actuating mechanism
110 can cause movement of the sheath 102, while the elongated
member 108 is connected to the handle 106, and remains stationary.
The actuating mechanism 110 can advance the sheath 102 over the
retrieval assembly 104 (which remains stationary), to enclose the
retrieval assembly 104 in a collapsed position within the sheath
102. Similarly, the actuation mechanism 110 can move the sheath 102
back, while the retrieval assembly 104 remains stationary, so that
at least a portion of the retrieval assembly 104 extends beyond the
distal end 112 of the sheath 102, placing the retrieval assembly
104 into the first or second positions.
[0035] It will be understood that the sheath 102, the retrieval
assembly 104, the handle 106, the elongated member 108, and the
actuating mechanism 110 as illustrated in FIG. 1 are not shown in
their correct size or proportion to each other. The sheath 102 is
dimensioned to fit the requirements of its application in the body.
For example, for urological applications, the diameter of the
sheath 102 is typically between 1.7 and 8.0 french, though some
applications may call for larger or smaller sizes.
[0036] Referring now to FIGS. 2A-C, the retrieval assembly 104 is
described in greater detail. FIG. 2A shows the distal end of the
sheath 102, in which the retrieval assembly 104 is in its collapsed
position. In this collapsed position, the retrieval assembly 104
fits within the sheath 102, and may be advanced while collapsed
within the sheath 102 into a position within a body.
[0037] FIG. 2B shows the retrieval assembly 104 partially extending
from the distal end of the sheath 102, to expose a portion of the
retrieval assembly 104, placing the retrieval assembly 104 in the
first position. In this first position, prongs 200a-200c of the
retrieval assembly 104 form an open ended grasper configuration
that may be used to grasp objects such as stones or calculi. An
operator retracts the retrieval assembly 104 slightly, either by
moving the retrieval assembly 104 or by moving the sheath 102, to
cause the prongs 200a-200c to move closer to each other, thereby
closing the grasper. The operator extends the retrieval assembly
104 slightly, either by moving the retrieval assembly 104 or by
moving the sheath 102, to cause the prongs 200a-200c to separate,
thereby opening the grasper. Actuation of the medical retrieval
device 100 over a range up to, and slightly beyond the first
position permits the retrieval assembly 104 to operate as a
grasper.
[0038] As can be seen, in this illustrative embodiment, the prongs
200a-200c have a generally curved shape when the retrieval assembly
104 is in the first position. This curved shape may assist in
grasping objects within the prongs 200a-200c.
[0039] FIG. 2C shows the retrieval assembly 104 fully extended from
the distal end of the sheath 102, to expose substantially the
entire retrieval assembly 104, placing the retrieval assembly 104
in the second position. In this second position, the prongs
200a-200c form a substantially close ended configuration that may
enclose objects such as stones or calculi within a basket formed by
the prongs 200a-200c. Advantageously, since the tips of the prongs
200a-200c are not connected to each other, an object may be
released from the basket formed by the prongs 200a-200c by
separating the ends of the prongs 200a-200c. An operator may
release an object from the retrieval assembly 104 by actuating the
medical device 100 to partially retract the retrieval assembly 104,
either by moving the retrieval assembly 104, or by moving the
sheath 102. Additionally, an object caught within the basket formed
by the prongs 200a-200c may apply a predetermined force (i.e.
sufficient force to separate at least one of the prongs 200a-200c
from the others), to open the distal end of the basket formed by
the prongs 200a-200c, thereby releasing the captured material.
[0040] In the second position, the distal portions of the prongs
200a-200c, which extended from the sheath 102 when the retrieval
assembly 104 was in the first position have reversed their
orientation, and have a shape that curves generally inward. This
inward-curving shape causes the distal end of the basket formed by
the prongs 200a-200c to have a narrow configuration.
[0041] As can be seen in FIGS. 2A-2C, the ends of the prongs
200a-200c comprise barbs 202a-202c. When the retrieval assembly 104
is in the first position, these barbs point generally inward,
towards a central or longitudinal axis 202 of the retrieval
assembly 104. In this configuration, the barbs 202a-202c may
enhance the ability of the retrieval assembly 104 to act as a
grasper, by catching on material held by the prongs 200a-200c.
[0042] When the retrieval assembly 104 is in the second position,
the barbs 202a-202c point outward, away from the longitudinal axis
202 of the retrieval assembly 104. In this configuration, the barbs
202a-202c do not interfere with the basket operation of the
retrieval assembly 104, and will not prevent objects from being
released from the basket formed by the prongs 200a-200c.
[0043] It will be understood that alternative embodiments of the
retrieval assembly 104 having a greater number of prongs can be
constructed, and that the selection of three prongs in the
retrieval assembly 104 is for illustrative purposes only.
Embodiments of a retrieval assembly for use with the present
invention will typically have either three or four prongs, though
configurations having a greater number of prongs are within the
scope of the invention.
[0044] The retrieval assembly 104, including the prongs 200a-200c,
may be produced in a variety of materials, including, but not
limited to nitinol, stainless steel, Co--Cr alloys, and titanium
alloys. The retrieval assembly 104 may be formed as a single unit
or by assembling the prongs 200a-200c.
[0045] Referring now to FIGS. 3A-3C, a second illustrative
embodiment of a retrieval assembly for use with the medical device
of the present invention is described. In FIG. 3A, a retrieval
assembly 300 is in a collapsed position within a distal end of a
sheath 302.
[0046] FIG. 3B shows the retrieval assembly 300 partially extending
from the distal end of the sheath 302, so that a portion of the
retrieval assembly 300 is exposed, placing the retrieval assembly
300 in the first position. In this first position, prongs 304a-304c
of the retrieval assembly 300 form an open configuration that may
be used to grasp objects such as stones or calculi. An operator can
slightly retract or extend the retrieval assembly 300 (either by
moving the retrieval assembly 300 or by moving the sheath 302) to
cause the prongs 304a-304c to move closer to each other, thereby
closing the grasper, or to separate farther from each other,
thereby opening the grasper. Actuation of the device over a range
up to, and slightly beyond the first position permits the retrieval
assembly 300 to operate as a grasper.
[0047] In this embodiment, the distal ends of the prongs 304a-304c
that extend from the sheath 302 when the retrieval assembly 300 is
in the first position have a generally linear shape. This shape is
determined, in part, by the shape of the basket that will be formed
by the prongs 304a-304c when the retrieval assembly is more fully
extended.
[0048] FIG. 3C shows the retrieval assembly 300 fully extended from
the distal end of the sheath 302, to expose substantially the
entire retrieval assembly 300, placing the retrieval assembly 300
in the second position. In this second position, the prongs
304a-304c form a substantially closed configuration that may
enclose objects such as stones or calculi within a basket formed by
the prongs 304a-304c. As in other embodiments, since the tips of
the prongs 304a-304c are not connected to each other, an object may
be released from the basket formed by the prongs 304a-304c by
separating the ends of the prongs 304a-304c. An operator may
release an object from the retrieval assembly 300 by partially
retracting the retrieval assembly 300, either by moving the
retrieval assembly 300 or by moving the sheath 302. Additionally,
an object caught within the basket formed by the prongs 304a-304c
may apply a predetermined force sufficient to separate at least one
of the prongs 304a-304c from the others, permitting the object to
escape.
[0049] Because of the generally linear shape of the distal ends of
the prongs 304a-304c, the basket formed by the prongs 304a-304c
when the retrieval assembly 300 is in the second position has a
generally convex form.
[0050] Referring to FIGS. 4A-4B, an alternative design for the
distal portions of the prongs of a retrieval assembly for use with
the medical device of the present invention is described. Each of
prongs 400a-400c of a retrieval assembly 402 includes a series of
teeth 404. As shown in FIG. 4A, when the retrieval assembly 402 is
in the first position, being used as a grasper, the teeth 404 face
inward, towards a longitudinal axis 406 of the retrieval assembly
402. In this configuration, the teeth 404 enhance the ability of
the retrieval assembly 402 to grasp objects such as stones or
calculi, and may prevent objects from being inadvertently released
from the grasper formed by the prongs 400a-400c.
[0051] As shown in FIG. 4B, when the retrieval assembly 402 is in
the second position, configured as a basket-type retrieval device,
the teeth 404 face outward, away from the longitudinal axis 406 of
the retrieval assembly 402. Because the teeth 404 face outward,
they will not interfere with the ability of the retrieval assembly
402 to release objects from the basket formed by the prongs
400a-400c. Additionally, because the teeth 404 are disposed on
distal portions of the prongs 400a-400c that do not typically come
into contact with tissue during retrieval of an object, the teeth
404 are unlikely to cause damage to tissue during the retrieval of
an object.
[0052] The teeth 404 may be formed on the distal portions of the
prongs 400a-400c through a variety of techniques, including
etching, cutting, or being formed or molded when a prong is formed
or molded. The number of teeth, their shapes, and the extent of the
distal portion of the prongs 400a-400c over which the teeth extend
may vary in alternative embodiments. Additionally, alternative
embodiments of the retrieval assembly 402 wherein the teeth 404 are
formed on one or more of the prongs 400a-400c, but not necessarily
on all of the prongs 400a-400c may be constructed.
[0053] FIGS. 5A and 5B show an alternative embodiment of a
retrieval assembly for use with the medical device of the present
invention, in which prongs 500a-500c have rolled tips, rather than
barbed tips, as shown in previous embodiments. In FIG. 5A, a
retrieval assembly 502 is in the first position, for use as a
grasper. Rolled tips 504a-504c of the prongs 500a-500c point
generally inward, towards a central or longitudinal axis 506 of the
retrieval assembly 502. In this configuration, the rolled tips
504a-504c may assist in grasping material between the prongs
500a-500c.
[0054] When the retrieval assembly 502 is in the second position,
the rolled tips 504a-504c point outward, away from the longitudinal
axis 506 of the retrieval assembly 502, so they do not interfere
with the operation of the retrieval assembly 502 as a basket-type
retrieval device. Advantageously, the rolled tips 504a-504c will
not catch on tissue, such as the side of the ureter, when a stone
or other material is released from the basket formed by the prongs
500a-500c by applying a force to separate the prongs.
[0055] It will be understood by one skilled in the art that other
configurations for the ends or tips of the prongs of a retrieval
assembly for use with the medical device of the present invention
are possible. For example, the tips may be rounded, spiral-shaped,
ball-tipped, or may have other shapes or configurations.
[0056] Referring now to FIGS. 6A-6D, a method of using the medical
device of the present invention as a grasper is described.
Typically, an operator inserts a distal portion of the device into
a body tract, such as the ureter of a patient, using an endoscope
or guidewire. The operator typically views the progress of the
operation through fluoroscopy, though other viewing methods may be
used.
[0057] As shown in FIG. 6A, with the retrieval assembly in the
collapsed position within a sheath 602, the operator maneuvers a
distal portion of a medical device 604 into position near a stone
606 that is to be retrieved or manipulated. When the distal portion
of the medical device 604 approaches the stone 606, the operator
actuates the medical device 604 to place a retrieval assembly 600
in the first position, to use the retrieval assembly 600 as a
grasper, as shown in FIG. 6B. As shown in FIG. 6C, the operator
maneuvers the retrieval assembly 600 so that the prongs of the
retrieval assembly 600 encompass at least a portion of the stone
606. As shown in FIG. 6D, the operator then actuates medical device
604 to cause the prongs of the retrieval assembly 600 to close,
thereby grasping a front portion of the stone 606. Once the stone
606 is grasped in the prongs of the retrieval assembly 600, it may
be retrieved or maneuvered. To release the stone 606, the operator
may actuate the medical device 604 to cause the prongs of the
retrieval assembly 600 to open, releasing the stone 606.
[0058] FIGS. 7A-7C show an illustrative example of a method of
using the medical device of the present invention as a retrieval
basket. In FIG. 7A, the operator maneuvers a distal portion of a
medical device 704, into position near a stone 706. During
insertion of the medical device 704 and maneuvering of the medical
device 704 into position, a retrieval assembly is typically kept in
a collapsed position within the sheath 702.
[0059] When the distal portion of the medical device 704 approaches
a stone 706, the operator actuates the medical device 704 to place
a retrieval assembly 700 in the second position, to use the
retrieval assembly 700 as a basket-type retrieval device, as shown
in FIG. 7B. Generally, the operator may capture the stone 706 by
placing the retrieval assembly 700 in the second position and then
maneuvering the retrieval assembly 700 around the stone 706 until
the stone 706 passes between the prongs of the retrieval assembly
700, and into the basket formed by the prongs of the retrieval
assembly 700.
[0060] As shown in FIG. 7C, once the stone 706 is captured in the
basket formed by the prongs of the retrieval assembly 700, the
medical device 704, along with the retrieval assembly 700 (which
remains in the second position), and the captured stone 706 may be
withdrawn from the body. If it becomes necessary to release the
stone 706, the operator may actuate the medical device 704 to cause
the prongs of the retrieval assembly 700 to separate, thereby
releasing the stone 706.
[0061] As shown in FIGS. 8A-8B, since the prongs of the retrieval
assembly are deformable, and are not connected at their distal ends
when the retrieval assembly is configured as a basket-type
retrieval device, a captured stone may be released when a stricture
is encountered through which the stone cannot pass. Advantageously,
this may prevent tissue damage that would be caused by attempting
to force a stone through such a stricture.
[0062] In FIG. 8A, a medical device 800, including a retrieval
assembly 804 has captured a stone 806 in a basket formed by the
prongs of the retrieval assembly 804 when the retrieval assembly
804 is in the second position. The medical device 800 is in the
process of being withdrawn from the patient, but will encounter a
stricture 808, which is too small to permit the stone 806 to
pass.
[0063] As shown in FIG. 8B, when the stricture 808 is encountered,
the stone 806 is unable to pass, and exerts force on a distal
portion of the prongs of the retrieval assembly 804. Because the
distal tips of the retrieval assembly 804 are not connected or
otherwise held together, when this force exceeds a predetermined
force (i.e. a force sufficient to cause one or more prongs of the
retrieval assembly 804 to separate), one or more of the prongs of
the retrieval assembly 804 will separate, releasing the stone
806.
[0064] Other embodiments incorporating the concepts disclosed
herein are within the spirit and scope of the invention. The
described embodiments are illustrative of the invention and not
restrictive.
* * * * *