U.S. patent number 4,295,464 [Application Number 06/131,937] was granted by the patent office on 1981-10-20 for ureteric stone extractor with two ballooned catheters.
Invention is credited to Alfred A. Shihata.
United States Patent |
4,295,464 |
Shihata |
October 20, 1981 |
Ureteric stone extractor with two ballooned catheters
Abstract
A ureteric stone extractor (100) is disclosed wherein an inner
dislodger catheter (101) is slidable within a relatively larger
outer dialator catheter (102). The dislodger catheter (101)
comprises a lumen (104) having a stiffening metal stylet (106)
therein to allow it to easily pass beyond a stone arrested within a
ureter. A dislodger balloon (107) is eccentrically attached to the
inner catheter (101) and can be inflated once the inner catheter
(101) is positioned above and beyond the arrested stone. Nylon
strings (110) positioned along longitudinal axes of the dislodger
balloon (107) are manipulable by an attending physician to ensure
that the dislodger catheter (101) and the strings (110) entrap the
stone and to apply a downward force by the dislodger balloon (107)
to the stone sufficient to dislodge it from the ureteral walls. The
outer dilator catheter (102) has a cylindrical dilator balloon
(113) attached thereto to effect distension and dilation of the
ureter below the arrested stone, thereby providing a sufficient
spacial area into which the stone can be moved.
Inventors: |
Shihata; Alfred A. (Grandville,
MI) |
Family
ID: |
22451679 |
Appl.
No.: |
06/131,937 |
Filed: |
March 21, 1980 |
Current U.S.
Class: |
606/127;
604/101.05; 604/27; 604/48; 604/908; 604/919; 606/128; 606/192 |
Current CPC
Class: |
A61B
17/22032 (20130101); A61M 25/1011 (20130101); A61M
2025/109 (20130101); A61M 2025/1052 (20130101) |
Current International
Class: |
A61B
17/22 (20060101); A61M 25/10 (20060101); A61B
019/00 (); A61B 017/00 (); A61M 025/00 (); A61M
029/02 () |
Field of
Search: |
;128/328,349R,349B,349BV,344,325,1R |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
"Some New Concepts of Stones of Uretal Stones," Progressive Surg.,
vol. 13, pp. 185-205, Karger, Basel, 1974. .
"Cystoscopic Rx of Stones in the Ureter with Spec. Reference to Lg.
Calculi, Based on 1550 Cases", Dourmashkin, R. L., pub. & date
unknown. .
"A Double-Balloon Ureteric Stone Extractor", The Lancet, Oct. 4,
1969, pp. 724, 725. .
Advertisement of V. Mueller Div. of American Hosp. Supply Corp.,
pp. 400-401, pub. & date unknown..
|
Primary Examiner: Michell; Robert W.
Assistant Examiner: Shedd; C. W.
Attorney, Agent or Firm: McGarry; John E.
Claims
The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. A stone extractor for extracting a ureteral stone arrested
within any of various sections of a ureter of a patient wherein
said various sections include ureteral sections above the lower
third sectional area of said ureter; said stone extractor
comprising:
first inflatable means for gradually applying an increasing outward
radial force to inner walls of said ureter wherein said inner walls
are distended in response to said radial force in a manner such
that a stress relaxation state is induced therein;
first catheter means connected to said first inflatable means and
adapted to position said first inflatable means below the position
of arrestment of said ureteral stone;
second inflatable means for applying a downward force to said
ureteral stone to achieve dislodgment of said stone from said inner
walls of said ureter;
second catheter means connected to said second inflatable means for
positioning said second inflatable means above the position of
arrestment of said ureteral stone; and
said second catheter means is adapted to adjust the position of
said second inflatable means relative to said first inflatable
means and is manually manipulable to move said ureteral stone into
a spacial area of said ureter distended by said first inflatable
means.
2. A stone extractor in accordance with claim 1 characterized in
that said second inflatable means comprises a dislodger balloon
connected to and arranged eccentrically about said second catheter
means.
3. A stone extractor in accordance with claim 1 or 2 characterized
in that said first catheter means comprises a dilator catheter
manually extendable into said ureter and connected to said first
inflatable means for positioning said first inflatable means below
said ureteral stone.
4. A stone extractor in accordance with claim 3 characterized in
that said first inflatable means comprises a dilator balloon
connected to and arranged concentrically about said dilator
catheter; and
said stone extractor further comprises means for inflating said
dilator balloon through said dilator catheter subsequent to
insertion of said dilator catheter into said ureter, wherein said
means for inflating said dilator balloon is manually operable
external to said ureter.
5. A stone extractor in accordance with claims 1 or 2 characterized
in that said stone extractor further comprises means connected to
said second catheter means for externally manipulating said second
inflatable means to move said uretal stone into said spacial area
of said inner walls of said ureter distended by said first
inflatable means.
6. A stone extractor in accordance with claim 5 characterized in
that said means for externally manipulable said second inflatable
means comprises a pair of strings connected to said second catheter
means.
7. A stone extractor in accordance with claims 1 or 2 characterized
in that said first catheter means comprises a dilator catheter
having a diameter in the range of 7 to 8 F and comprising a
dislodger lumen having openings at proximal and distal ends, and a
relatively smaller inflating lumen having openings (115, 116) at
proximal and distal ends;
said first inflatable means comprises a dilator balloon having a
cylindrical shape and arranged concentrically about said first
lumen of said dilator catheter at said proximal end, said dilator
balloon inflatable by injection of material through said opening of
said second lumen at the distal end and through said proximal
opening of said second lumen; and
said dilator balloon having a volumetric capacity in the range of 9
to 11 cubic centimeters.
8. A stone extractor apparatus in accordance with claim 7
characterized in that said second catheter means comprises:
a dislodger catheter having a diameter in the range of 3 to 4 F and
comprising a lumen having an opening (108) at its proximal end and
an opening (109) at its distal end;
a dislodger balloon connected to said dislodger catheter and
arranged eccentrically about said lumen of said dislodger catheter,
said dislodger balloon inflatable by injection of material through
said openings (109) 108) of said lumen of said dislodger
catheter;
said dislodger balloon having a volmetric capacity in the range of
1 to 3 cubic centimeters; and
said dislodger catheter is manually insertable through and beyond
said first lumen of said dilator catheter.
9. A stone extractor in accordance with claim 1 characterized in
that said second inflatable means is adapted to prohibit extensive
migration of said ureteral stone toward a kidney of said
patient.
10. A stone extractor in accordance with claim 1 characterized in
that said second catheter means comprises a dislodger catheter
manually extendable into said ureter and connected to said second
inflatable means for positioning said second inflatable means above
said ureteral stone.
11. A stone extractor in accordance with claim 10 characterized in
that said dislodger catheter terminates in a tapered end comprising
a flexible material having wire means therein to provide rigidity
for insertion of said dislodger catheter into said ureter.
12. A stone extractor in accordance with claim 10 characterized in
that said first catheter means comprises a dilator catheter
manually extendable into said ureter and connected to said first
inflatable means for positioning said first inflatable means below
said ureteral stone; and
said dislodger catheter is manually extendable through and beyond
said dilator catheter.
13. A stone extractor in accordance with claim 12 characterized in
that said stone extractor further comprises means selectively
extendable into said dislodger catheter for effecting substantial
rigidity of said stone extractor during insertion of said dislodger
catheter and said dilator catheter into said ureter.
14. A stone extractor in accordance with claim 13 characterized in
that said means for effecting rigidity comprises a metal stylet
having a diameter smaller than the diameter of said dislodger
catheter.
15. A stone extractor in accordance with claim 10 characterized in
that said second inflatable means comprises a dislodger balloon
connected to and arranged eccentrically about said dislodger
catheter; and
said stone extractor further comprises means for inflating said
dislodger balloon through said dislodger catheter subsequent to
insertion of said dislodger catheter into said ureter.
16. A method for extracting a stone arrested in a ureter of a
patient above the pelvi-ureteric junction, said method comprising
the steps of:
(a) applying a gradually increasing outward radial force to a first
portion of inner walls of said ureter immediately below the
position of said stone within said ureter and sufficient to induce
a stress relaxation state of said inner walls to the extent that
the diameter of a spacial area at said first portion of said inner
walls is larger than the maximum diameter of said stone;
(b) ceasing application of said radial force at said first
portion;
(c) applying a downward force from a position above the position of
said stone sufficient to dislodge said stone from said inner walls
while said first portion of said inner walls are in said stress
relaxation state;
(d) manipulating said stone downward into said spacial area at said
first portion of said inner walls of said ureter; and
(e) sequentially repeating steps (a) through (d) at successive
lower portions of said inner walls of said ureter until said stone
passes into the bladder area of said patient.
17. The method in accordance with claim 16 characterized in that
said method further comprises prohibiting, migration of said stone
toward a kidney of said patient prior to step (a).
Description
BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates to medical treatment of stones arrested
within a ureter, and more specifically, relates to catheter
apparatus and methods for extracting ureteric stones without
necessitating major surgery.
2. State of the Prior Art
For many years, individuals have been medically plagued by stones
normally formed in renal calyces or the pelvis which pass to and
are arrested within the ureter. Among other medical problems, these
stones often cause blockage of urine produced by the kidneys with
resultant ureteral colic and accompanying severe pain. It has long
been recognized advantageous to treat patients having ureteric
stones using procedures which do not require major open surgery
involving incisions of the ureter. The dangers and complications
associated with such surgery are well-known to any physician.
Further, certain patients have medical histories prohibiting major
surgery involving the ureteral area.
One early treatment procedure for ureteral stones was based on the
concept that spasm in the smooth muscle of the ureteral wall
prevented passage of the stone and passage of urine around the
stone. Accordingly, the procedure involved use of spasmolytic
drugs. However, it has been shown in various studies that spasm of
the ureteral wall is not an overriding factor in the arrestment of
ureteral stones. Therefore, spasmolytic drugs are not substantially
effective.
Other early treatment procedures were based on the simple
mechanical principle that a stone is arrested in the ureter when
the force which is driving downward on the stone is smaller than
the frictional force occurring between the stone and the ureteral
wall. Historically, it was therefore thought that any treatment
method which increased the downward driving force on the stone
would be valuable to accomplish stone passage. Accordingly,
patients were urged to increase fluid intake, thereby increasing
the volume and resultant pressure of urine produced by the kidneys
which was blocked above the stone. However, studies have shown that
sudden pressure increase above the ureteral stone caused by
discharge of urine from the kidneys actually causes an increased
magnitude of frictional force between the stone and the ureteral
wall. Therefore, passage of the ureteral stone is not facilitated
by the increased urine, and further, severity of ureteral colic is
actually increased.
The treatment procedures which merely attempt to increase the
magnitude of downward forces above the arrested stone do not take
into consideration the mechanical principles of frictional forces
or the interrelationships of these principles to the physiological
composition of the ureter. The frictional force at a point of
contact between surfaces of the stone and the ureteral wall is
equivalent to the product of a coefficient of friction and the
force pressing between the stone and wall perpendicular to the
plane of contact of the surfaces. A coefficient of friction for any
two particular surfaces is dependent only on the materials involved
and the "condition" of the surfaces.
As now understood in the physiological arts, the magnitude of the
aforementioned perpendicular force between the stone and the
ureteral wall is dependent upon several factors. These factors
comprise: stone size, ureter width, and distensibility of the
ureteral wall. Regarding stone size, the tensional force of the
ureteral wall at the location of arrestment of the ureteral stone
increases with respect to the diameter of the stone. As a general
rule, stones having a diameter smaller than 2 millimeters pass
through the ureter without causing substantial difficulty. Stones
having a diameter greater than 2 millimeters but less than 4
millimeters also usually pass through the ureter but can cause
associated ureteral colic. Various studies have shown that stones
having a diameter of 4 to 6 millimeters independently pass through
the ureter at a rate of approximately 50%. Stones having a diameter
greater than 6 millimeters seldom pass through the ureter without
medical treatment.
As known in the medical arts, the ureter comprises three sections
of relatively narrow width. Frictional force between the stone and
the ureter of course becomes greater at these narrow sections.
Accordingly, it is at these sections that stones are often
arrested. The relatively narrow sections are commonly known as the
pyelo-ureteral conjunction, the passage over the crossing of iliac
vessels and the uretro vesical junction which is the distal portion
of the ureter.
Frictional forces between an object and a tubular structure
surrounding the object increase inversely with the distensibility
of the tubular structure. The distensibility of the ureteral walls
is dependent on the individual distensibilities and arrangement of
the materials composing the walls. The ureteral walls comprise
approximately 70% fibrous collagen tissue having a distensibility
substantially equivalent to 0.01% of the distensibility of smooth
muscle fiber which substantially comprises the remainder of the
ureteral wall composition. Accordingly, it is the collagen tissue
that is determinative of the distensibility of the ureter and
corresponding frictional force between a stone and the ureteral
walls. Further, a moderate distension of the ureteral walls in the
upper and middle portions of the ureter causes the collagen fibers
to become contentrically arranged around the ureter lumen. Collagen
fibers are always concentrically arranged in the lower portion of
the lumen. This concentric arrangement offers substantial
resistance to distension of the ureteral walls and, accordingly,
produces large frictional forces in response to attempted
distension.
With knowledge of the densities and arrangement of the collagen and
muscle fibers in the ureter, it is surprising that relatively large
stones will sometimes independently pass through the ureter. This
phenomenon can be explained in view of the "visco-elastic" behavior
of living tissue. In accordance with general mechanical principles,
when a force is applied upon an elastic body, the deformation of
the body is proportional to the magnitude of the force. This
principle is commonly known as "Hooke's Law." The deformation of a
visco-elastic material depends not only on the magnitude of the
force applied to the material, but also upon the duration of the
applied force. All living tissue, including collagen tissue, has
visco-elastic properties. If a constant force is applied to such
visco-elastic material, the material continuously "stretches" until
it reaches an equilibrium state. This stretching and adjustment to
equilibrium is commonly known as "creep." Further, if visco-elastic
living tissue is stretched and then maintained at its new position
for a substantial period of time, the tensional force generated by
the living tissue will fall to a steady-state value. This
particular principal is commonly known as "stress relaxation."
The aforementioned principles of creep and stress relaxation can
readily be applied to arrestment of stones within a ureter. As a
stone passes into the ureteral area, there is a distension of the
ureteral walls which produces substantially large resistance and
resultant frictional forces with the stone. Accordingly, the stone
is arrested within the ureter. If the stone has been arrested at a
particular position on the ureteral wall for a substantial period
of time, the tensional force of the ureteral wall gradually ceases
in accordance with the principle of stress relaxation. Accordingly,
the frictional force between the stone and the ureteral wall will
decrease and a stone can often pass from its arrested position
towards the bladder.
However, other physiological phenomenon also occur when a ureteral
wall is continuously deformed at a position of arrestment of a
stone. As known in the medical art, a horizontal "bar" of the
ureteral wall materials will often be formed below the stone,
effectively blocking its passage. The size of this horizontal bar
depends on the magnitude and duration of the driving force of the
stone. It is this bar which often occurs when the pressure of urine
above the stone increases.
Several types of devices exist in the prior art which are designed
to extract ureteric stones without necessity of major open surgery.
However, each of these devices suffers from limitations not found
in the present invention and does not take into consideration all
of the mechanical and physiological principles previously discussed
herein. Further, substantially all of these devices are limited to
extractions of ureteral stones in the lower one-third of the ureter
with limited success to extract any stones above the lower third
section. Additionally, these devices can produce varying degrees of
trauma to the ureter and are therefor somewhat dangerous.
One such prior art device is commonly known as the Dormia ureteral
stone dislodger. This device, and devices having limited
modifications thereof, are utilized in a large percentage of
medical centers now performing ureteral stone extraction. The basic
Dormia stone dislodger comprises a catheter having a retractable
spring wire mechanism. The spring wire mechanism is operable to
activate a four wire pear-shaped basket having an opening therein
to entrap a ureteral stone. The Dormia stone dislodger, like other
prior art devices, is limited to extraction of ureteral stones in
the lower third section of the ureter. Further, this dislodger is
substantially limited in usefulness to extract stones having a
diameter smaller than 8 millimeters.
Several other limitations of the Dormia stone dislodger also exist.
The structure of the basket and the materials of which it is
compressed can cause entrapment of the basket within the ureter
and/or possible perforation of the ureteral wall. Additionally, the
lack of expansive power of the wires of the pear-shaped basket to
fully dilate the ureter has caused a substantially high failure
rate when attempting stone extraction.
Another prior art device comprises a single catheter with two
inflatable balloons located at concentric predetermined positions
near the tip of the catheter. A syringe plunger attached to the
lower end of the catheter provides variation in balloon size while
the catheter is positioned in the ureter. The catheter is
manipulated so that the arrested stone is between the balloons and
is then slowly withdrawn with the lower balloon acting as a dilator
and the upper balloon pushing the stone toward the bladder. With
only a single catheter, this device does not allow the balloons to
be separately manipulated. Further, the fixed positional
relationship of the balloons and the concentric attachment of the
upper balloon to the catheter limits the adaptability of the device
to achieve extraction of relatively large stones, and, more
particularly, the extraction of any size arrested above the lower
third ureter section.
SUMMARY OF THE INVENTION
Advantageously, a technical advance is achieved in a ureteric stone
extractor capable of extracting ureteral stones arrested above the
lower one-third section of a ureter and further capable of
extracting stones having a diameter greater than 8 millimeters. The
stone extractor comprises structure and materials adapted to
substantially minimize failure of accomplishment of stone
extraction and complications which can arise therefrom.
The extractor comprises a first catheter means for positioning a
first inflatable means below the position of arrestment of the
ureteral stone. A second catheter means is adapted to apply a
downward force to the ureteral stone sufficient to achieve
dislodgement of the stone from the inner walls of the ureter. The
first inflatable means applies an outward radial force to the
ureter inner walls to distend the same in response to the force in
a manner such that a stress relaxation state is achieved. The
second catheter means is manually manipulable to move the ureteral
stone into the ureteric area distended by the first inflatable
means.
The second catheter means is connected to a second inflatable means
which is positionable above the position of arrestment of the
ureteral stone for dislodging the ureteral stone from the ureter
inner walls. The second inflatable means is movable relative to the
first inflatable means and is eccentrically arranged about the
second catheter means. The second catheter means comprises a
dislodger catheter connected to the second inflatable means for
manually extending the second inflatable means to the position
above the ureteral stone. The first catheter means comprises a
dilator catheter extendible into the ureter and connected to the
first inflatable means for positioning the first inflatable means
below the ureteral stone. Additionally, the dislodger catheter
means is extendible through and beyond the dilator catheter
means.
The first inflatable means comprises a dilator balloon having a
cylindrical shape and arranged concentrically about a first lumen
of the dilator catheter and inflatable by injection of material
through openings of first lumen. The second inflatable means
comprises a dislodger balloon connected to the dislodger catheter
and arranged eccentrically about a lumen of the dislodger catheter.
The dislodger balloon is inflatable by injection of material
through openings of the dislodger lumen.
A method for achieving stone extraction in accordance with the
invention comprises the application of a gradually increasing
outward radial force to the inner walls of the ureter immediately
below the position of the arrested stone. This increasing radial
force is sufficient to induce stress relaxation of the inner walls
to the extent that the diameter of the spacial area between the
walls at the position of concentric force application is larger
than the maximum diameter of the stone. The application of the
concentric force is then ceased and a downward force is applied
from a position above the stone sufficient to dislodge the stone
from the inner walls. The stone is then manipulated into the
spacial area already dilated by application of the radial force.
The aforementioned procedure is repeated until the stone passes
into the bladder area of the patient.
BRIEF DESCRIPTION OF DRAWINGS
The invention will now be described with reference to the drawings
in which:
FIG. 1 depicts a sectional view of one illustrative embodiment of a
ureteric stone extractor in accordance with the invention;
FIG. 2 is a sectional view of the ureteric stone extractor shown in
FIG. 1 in a ureter with the balloon elements of the extractor in an
inflated position with the metal stylet removed;
FIG. 3 depicts a cross-sectional top view of the ureteric stone
extractor shown in FIG. 1 taken along the axis 3--3 of FIG. 1;
FIG. 4 depicts a cross-sectional top view of the ureteric stone
extractor shown in FIG. 1 taken along axis 4--4 of FIG. 1;
FIG. 5 depicts a cross-sectional top view of the ureteric stone
extractor shown in FIG. 2 taken along axis 5--5 of FIG. 2;
FIG. 6 depicts a cross-sectional top view of the ureteric stone
extractor shown in FIG. 2 taken along axis 6--6 of FIG. 2.
DETAILED DESCRIPTION
The invention will now be described with reference to the drawings
and to FIGS. 1, 3 and 4 in particular. The principles of this
invention are disclosed, by way of example, in a ureteric stone
extractor 100. A stone extractor of this type can be utilized for
removing ureteral stones without necessitating major open surgery
on the patient. As will be described herein, extractor 100 is
adapted to apply a downward force above the position of ureteral
stone arrestment and correspondingly decrease the frictional
attraction between the stone and ureteral inner walls by dilating
the ureter sufficiently to induce a stress relaxation state.
Extractor 100 comprises an inner dislodger catheter 101 and an
outer dilator catheter 102 as shown in FIG. 1. Dislodger catheter
101 is depicted in FIG. 1 extending through and in part beyond
dilator catheter 102. Catheter 101 can be manually extended into a
patient's ureter and beyond the dilator catheter 102 and provides a
means for positioning subsequently described apparatus above the
arrested stone. Dislodger catheter 101 comprises tubular walls 103
within a cylindrical lumen 104 formed therein. Catheter 101
terminates at its far end in a conical tapering structure 105
comprising a filiform tip, flexible but having, for example, a
spring wire inner core or the like to provide sufficient rigidity
for insertion into the ureter. Preferably, the size of the
dislodger catheter 101 can comprise a diameter at its maximum width
of approximately 3 to 4 F. (F is a standard unit of measure for
catheters commonly known and used in the medical arts and is
approximately equal to 0.33 millimeters).
Within the lumen 104 of dislodger catheter 101 is a metal stylet
106 which provides a stiffening effect necessary to allow the end
of catheter 101 to easily pass beyond a stone arrested within the
ureter.
Connected to dislodger catheter 101 is an eccentric balloon 107
which is attached to the exterior of tubular walls 103 near the top
of lumen 104 through a suitable adhesive 120. Dislodger balloon 107
is depicted in FIG. 1 in a deflated state and provides an
inflatable means for applying, at a requisite time as subsequently
described herein, a downward force sufficient to dislodge the
arrested stone. Additionally, when balloon 107 is in an inflated
state, migration of the dislodged stone toward the kidneys is
prohibited. As shown in subsequently described figures of the
drawing herein, dislodger balloon 107 is eccentric with respect to
the tubular structure of dislodger catheter 101 to enable the
balloon to be positioned immediately above the stone during the
extraction process.
The dislodger balloon 107 is connected to the tubular walls 103 of
dislodger catheter 101 in a manner and position such that an
opening 108 in the tubular walls 103 from lumen 104 is interior to
balloon 107. An additional opening 109 of lumen 104 exists at the
lower end of stone extractor 100. Opening 109 remains external to
the patient's ureter during all phases of the extraction process. A
suitable syringe or other means (not shown) can be utilized to
inject a material into lumen 104 to inflate the dislodger balloon
107 to a requisite size after positioning thereof. As evident to
any physician having knowledge of the invention, a radio-opaque
inflation material can be advantageously utilized to provide
visualization by the physician via X-ray type machines commonly
known in the medical art. When the eccentric dislodger balloon 107
is inflated to a requisite size, a stopcock or other suitable means
can be utilized to close the lumen opening 109. Dislodger 107 can
be of any suitable volumetric capacity, preferrably such as
approximately 2 cubic centimeters (cc).
Attached to and passing longitudinally around the eccentric
dislodger balloon 107 are a pair of strings 110, one of which is
shown in FIG. 1. Strings 110 provide a means for manually
manipulating dislodger balloon 107 to achieve dislodgement of the
arrested stone and to move it downward into an area of the ureter
dilated in a manner subsequently described herein. Further, the
strings allow the application of pressure to maintain balloon 107
in a correct spacial position. Strings 110 are preferably composed
of nylon material or the like, and are attached to dislodger
balloon 107 at suitable positions subsequently described herein.
The strings are preferably further attached to the base of filiform
tip 105 to provide greater stability. Strings 110 pass from the
dislodger balloon 107 to the external area of the patient's ureter
along the exterior of tubular walls 103 of dislodger catheter 101.
These strings are accessible to the physician and utilized for
manipulation of eccentric balloon 107 during the stone extraction
process.
Surrounding the dislodger catheter 101 is the relatively larger
outer dilator catheter 102 as shown in FIGS. 1, 4 and 6. Dilator
catheter 102 provides an extendable means for positioning
subsequently described inflatable means below the arrested stone
and gradually dilating the ureter through the use thereof. Catheter
102 comprises a cylindrical structure having substantially tubular
walls 111 which form an open-ended first lumen 112 therein. The
dilator catheter 102 is of a requisite size to allow the dislodger
catheter 101 to be slidably received within first lumen 112 and
extendable beyond its open upper end. This extension capability
allows the previously described dislodger balloon 107 to be passed
beyond and come in contact with the upper portion of the ureter
above the stone for purposes of applying a downward dislodging
force. Preferrably, catheter 102 can have a maximum width diameter
of approximately 7 to 8 F, which is sufficiently small to readily
allow insertion thereof into the ureter.
Connected to the upper portion of dilator catheter 102 is a dilator
balloon 113 cylindrical in shape and arranged concentrically around
the exterior tubular walls 111. Dilator balloon 113 is depicted in
a deflated state in FIG. 1 similar to dislodger balloon 107. As
subsequently described herein, balloon 113 provides an inflatable
means for applying a gradually increasing outward radial force to
the inner walls of the ureter immediately below the arrested stone,
thereby distending the ureteral walls and dilating the spacial area
therebetween.
Catheter 102 further comprises a second cylindrically shaped lumen
114 relatively smaller than first lumen 112 and formed by wall 119.
Lumen 114 is closed at its upper portion and comprises an opening
115 through tubular walls 111. The dilator balloon 113 is connected
to catheter 102 in a manner and position such that opening 115 is
interior to balloon 113. An additional opening 116 to lumen 114
exists at the lower end of catheter 102 and remains external to the
ureter during the extraction process. In a manner similar to that
previously described with respect to dislodger balloon 107, the
attending physician can utilize a syringe or other suitable means
to inject a radio-opaque material into lumen 114 through opening
116, thereby inflating dilator balloon 113 via opening 115. When
dilator balloon 113 is inflated to its requisite size, a stopcock
or other suitable means can be utilized to close opening 116.
Dilator balloon 113 can be of any suitable volumetric capacity,
preferrably, a capacity of approximately 10 cc. Catheters 101 and
102 can be composed of any materials generally known in the arts
which are suitable for insertion into human organs. For example,
the catheters can comprise Teflon or like material. Further, the
previously described dislodger balloon 107 can be reinforced with
Latex rubber layers 122 or other suitable materials at positions
where strings 110 attach and pull on the balloon 107, and above the
area in contact with the arrested stone.
Reference is now made to FIGS. 2, 5 and 6 for a description of the
operation of the invention. The dislodger balloon 107 and dilator
balloon 113 are both in an inflated state. It should be noted that
FIG. 2 does not depict the metal stylet 106 which is removed by the
physician once the extractor 100 is in suitable position within the
patient's ureter.
Before the extraction process begins, the patient is normally put
under a general anesthesia in a lithotomy position, which is a
position commonly known in the medical art and utilized when a
physician makes a cystoscopic examination to extract a stone by
manipulation. Commonly known X-ray apparatus and an image
intensifier screen are utilized throughout the extraction procedure
to provide visual location of the stone and to further provide
visual indications of the relative positions of the previously
described catheters and balloons with respect to the stone.
Preferably, the ureteric orifice is initially catheterized for
purposes of gently injecting a sterile mineral oil or like
substance in the ureter where the stone is arrested. The injected
mineral oil provides additional lubrication for purposes of
decreasing the friction between the arrested stone and the ureteral
walls, thereby aiding the extraction process.
By means such as a suitable linear panendoscope (e.g. a McCarthy's
foroblique cystoscope well known in the medical arts), the ureteric
stone extractor 100 is introduced into the ureter through the
ureteric orifice. Extractor 100 is passed up through the ureter
while visualized by the physician on the image intensifier screen.
FIGS. 2, 5 and 6 depict extractor 100 within the area between
ureteral walls 117. At the time extractor 100 is in a suitable
position with respect to the arrested stone, dislodger catheter 101
is extended through and beyond the dilator catheter 102. It can be
somewhat useful to the extraction process if the extension of
dislodger catheter 101 causes partial dislodgement of the arrested
stone and slight movement towards the upper portion of the ureter
and the kidney. This action is useful since the portion of the
ureter above the arrested stone is normally somewhat dilated and
provides a larger spacial area for subsequent manipulation.
The dislodger catheter 101 is extended until it appears to the
physician that the presently delfated dislodger balloon 107 is
positioned above the stone. When the physician is certain of
correct positioning, metal stylet 106 is removed from lumen 104 of
catheter 101. It should be noted that FIG. 2 does not depict stylet
106 since removal occurs prior to inflation of balloons 107 and
113. Dislodger balloon 107 is then inflated with radio-opaque
material in a manner previously described with respect to FIG. 1.
Balloon 107 is inflated sufficiently to prohibit possible extensive
migration of the stone 201 towards the kidneys if it becomes
completely dislodged. FIG. 2 depicts the dislodger balloon 107 in
an inflated state above a stone 201 to be extracted.
Dilator catheter 102 is then positioned such that dilator balloon
113 is immediately below stone 201. Balloon 113 is then also
inflated with radio-opaque material in the manner described with
respect to FIG. 1. The process of inflation of dilator balloon 113
is performed in a gentle and gradual manner to slowly apply an
increasing radial force to the inner walls of the ureter below the
position of arrestment of stone 201. This application of radial
force is of a magnitude and duration to distend the uretal inner
walls sufficiently to induce a stress relaxation state therein as
described in the section entitled "Background of the Invention."
Correspondingly, the spacial area in the ureter below the stone.
Balloon 113 is inflated until the minimum lateral diameter of the
dilated spacial area is greater than the maximum diameter of stone
201. This requisite inflation is readily visualized and determined
by the attending physician via the image intensifier screen.
When requisite inflation has occurred and the aforementioned stress
relaxation state has been induced, dilator balloon 113 is deflated.
Dilator catheter 101 is then withdrawn downwards until balloon 113
is in next non-dilated area of the ureter. Dilator balloon 13 is
then again gradually inflated in the manner previously
described.
With the spacial area below the stone distended, dislodger catheter
101 and dislodger balloon 107 are manipulated, by lated, by
previously described strings 110, to dislodge the arrested stone
201 and move it downward into the dilated spacial area. It is
advantageous, for manipulation purposes, to attach the pair of
strings 110 to dislodger catheter 101 and balloon 107 in a manner
such that the strings remain substantially equidistant from the
walls 103 of catheter 101. The process of distending the inner
ureteral walls to a stress relaxation state below the stone by
dilator balloon 113, deflating balloon 113, and moving the stone
201 to the dilated spacial area of the ureter is repeated until
stone 201 passes through the ureter and into the patient's bladder.
When stone 201 is within the bladder, it can easily be retrieved by
the attending physician.
A stone extractor of the type depicted as extractor apparatus 100
and described herein in accordance with the invention has several
advantages over prior art stone extraction systems. The absence of
metal wires on the exterior of the apparatus which can accidentally
protrude into ureteral walls provides a substantial probability of
trauma occurring to the ureter during the previously described
extraction procedure. Further, there is no chance of broken metal
or metal being accidentally caught within the ureter which is
unable to be withdrawn without major surgery. Additionally,
relatively large sized stones can be withdrawn by utilization of an
extractor in accordance with the invention, provided that the
attending physician has the patience and skill to gradually dilate
the ureter before attempting to manipulate the stone into the
dilated area. Further, the utilization of an inflatable means such
as a balloon which can be gradually inflated is physiologically
advantageous for distending the ureteral walls and dilating the
ureter. Conversely, any means of dilation which utilizes a sudden
or rapid ureteral wall distension can cause folds of mucosa to be
produced ahead of the stone. The mucosal folds can be damaged if an
extraction force is then applied to the stone.
The principles of the invention are not limited to a stone
extractor completely equivalent to the extractor 100 described
herein. It will be apparent to those skilled in the medical arts
that modifications and variations of the above-described
illustrative embodiment of the invention may be effected without
departing from the spirit and scope of the novel concepts of the
invention.
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