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The present invention relates to an angioplasty apparatus for removing
abnormal deposits from interior coronary or peripheric arterial walls and
the like.
Devices for removing abnormal deposits from arterial walls in the human
body are known in the art. In particular, U.S. Pat. No. 4,445,509 to Auth
shows a method and apparatus for the removal of abnormal deposits from the
interior walls of a blood vessel. The Auth device includes an elliptical
cutting tool mounted at one end of a hollow flexible rotating drive shaft
that extend sinto a catheter. When the catheter and cutting tool are
inserted into the blood vessel, the cutting tool is rotated by an actuator
which is located exterior to the catheter and coupled to the other end of
the drive shaft. Cutting flutes are provided on the cutting tool for
engaging with and cutting tissue to remove it from the vessel walls. The
cut particles of the deposit are withdrawn from the blood vessel through
radial ports providedin the cutting tool and into the hollow shaft by way
of a suction device.
The Auth device operates on the principle of cutting materials with
different physical characateristics and implements a high speed rotating
cutting tool. In desired operation, the soft vessel tissue when contacted
with the spinning cutting flutes deforms under the force and thus, is not
damaged. However, the more rigid deposit tissue is cut under contact with
the flutes.
However, a number of problems exist in the Auth device. Since the flexible
drive shaft is not provided with means for locating and securing it in the
vessel, the cutting tool is able to move with respect to the deposit,
thereby reducing the effectiveness of the device. Also, since the shape of
the cutting tool is fixed, the device cannot operate effectively in
various size vessels. Moreover, since the Auth device relies on the
healthy vessel tissue deforming under contact with the cutting tool,
damage can often occur to the healthy vessel tissue. Accordingly, there is
a need for an improved angioplasty apparatus for removing abnormal
deposits from the interior walls of blood vessels and the like.
It is an object of the present invention to obviate or mitigate the above
disadvantages.
According to the present invention there is provided an angioplasty
apparatus for removing abnormal deposits such as atheromatic plaque from
the interior walls of blood vessles and the like comprising:
a hollow elongate flexible member having one end for insertion into said
vessel;
a driving member coupled at one end to said elongate member and extending
forwardly at the other end into a vessel;
milling means coupled to a driving member exterior to said elongate
flexible member;
drive means in communication with said driving member for actuating said
driving member , said driving member rotating said milling means
alternately in opposite directions to engage and mill said deposits upon
actuation thereof by said drive means;
suction means in communication with said elongate flexible member for
withdrawing milled particles of said deposit from said vessel and into
said elongated flexible member ; and
sensing means located on said elongate flexible member and being for
coupling between said vessel and said milling means for sensing when said
milling means has removed said deposit from, the interior walls of said
vessel.
Preferably, the sensing means comprises a potential voltage source, a
current comparator and a pair of resistive circuits for the electrical
resistance between a healthy arterial section of vessel tissue and that of
the tissue contacted by the milling means.
Preferably, the milling means is a flexible leaf-shaped milling tool
provided with shallow milling flutes to reduce greatly the occurrence of
damage to the vessel tissue underlying the deposit to be removed. It is
also preferred that the apparatus includes an inflatable member for
securing the flexible member in position in the blood vessel.
Preferably, the elongate member is linearly displaceable with respect to
the driving member in order to impart a force on the flexible milling tool
to cause a change in the radial dimension of the milling tool. This allows
the apparatus to operate effectively in various size arterial branches and
to remove atheromatic deposits of different sizes.
It is also preferred that the angioplasty apparatus further includes a
linear displacement means disposed on the other end of the driving member
to allow the millingmeans to be displaced linearly therealong while still
being rotated alternately in opposite directions. In this manner, a large
deposit in a vessel can be removed without requiring the milling means to
be repositioned in the vessel.
The present apparatus provides the advantages of allowing large deposits to
be removed effectively and safety from blood vessels without frequent
repositioning of the apparatus in the vessel. Furthermore, the sensing
means, the inflatable member and the shallow cutting flutes provided on
milling means allow the apparatus to remove the abnormal deposits of
various sizes from various size blood vessels while greatly reducing the
occurrence of damage to the vessels.
Embodiments of the present invention will now be described by way of
example only with reference to the accompanying drawings in which:
FIGS. 1a and 1b are partial perspective sectional views of one end of an
angioplasty apparatus;
FIGS. 2a and 2b are partial perspective sectional views of the one end
illustrated in FIGS. 1a and 1b in operation;
FIG. 3 is a partial perspective sectional view of the other end of an
angioplasty apparatus;
FIGS. 4a and 4b are partial perspective sectional views of one end of
another angioplasty apparatus;
FIGS. 5a and 5b are partial perspective sectional views of FIGS. 4a and 4b
taken along lines 5--5;
FIG. 6 is a partial perspective sectional view of another portion of the
other end of the apparatuses illustrated in FIGS. 4 and 5;
FIGS. 7a and 7b are partial perspective sectional views of one end of still
yet other angioplasty apparatuses;
FIGS. 8a, 8b and 8c are partial perspective sectional views of other
angioplasty apparatuses;
FIGS. 9a, 9b and 9c are partial perspective sectional views of still yet
other angioplasty apparatuses;
FIGS. 10a, 10b, 10c, 10d, 10eand 10f are partial perspective views of
portions of the apparatuses illustrated in FIGS. 8 and 9;
FIGS. 11a and 11b are partial perspective views of the apparatuses
illustrated in FIGS. 8 and 9 in operation;
FIGS. 12a and 12b are perspective views of still yet other angioplasty
apparatuses; and
FIGS. 13a and 13b are perspective views of still yet other angioplasty
apparatuses.
Referring to FIGS. 1, 2 and 3, an angioplasty apparatus 10 is shown. The
apparatus includes an elongate cylindrical flexible hollow plastic outer
tube 12 for insertion into a blood vessel (not shown). A drive mechanism
16 is provided to rotate a milling tool 18 alternatively in opposite
directions in order to remove abnormal deposits (not shown) from the walls
of the vessel. A sensing device 20 is also provided for detecting when the
abnormal deposit has been removed from the vessel by comparing the
electrical resistance of healthy arterial tissue with that of the tissue
contacted by the milling tool 18.
The outer tube 12 includes an outer wall 22 and an inner wall 24 defining
outer and inner passages 26 and 28 respectively. A base plate 30 is sealed
on one end of the outer tube and has a central bore provided therein for
allowing the driving mechanism 16 to extend beyond the end of the outer
tube 12 and into the vessel. The inner wall 24 has a portion of its
structure removed proximal to the base plate 30 to provide an opening 32
between the inner passage 28 and the outer passage 26. A plate 34 is
positioned in the outer passage 26 and is tightly sealed between the inner
and outer walls 24 and 22 to divide the outer passage 26 into upper and
lower portions 26a and 26b respectively. An annular valve 40 moveable
between opened and closed positions is located adjacent the plate 34 on
opposite sides of the inner wall 24 of the lower portion 26b, to provide a
second path from the outer passage 26 to the inner passage 28.
A circular isolating plate 42 is located in the inner passage 28 near the
base plate 30 and is tightly sealed to the inner wall 24. The isolating
plate 42 is also provided with a central bore in alignment with the bore
provided in the base plate 30.
The other end of the inner and outer walls 22 and 24 are sealed to form an
annular shoulder 44. Drainage tubes 48 and 50 outwardly extend from the
inner passage 28 to the exterior of the outer tube 12 to provide a path
from the inner passage 28 to the exterior of the outer tube 12. The
drainage tubes 48 and 50 are also connected to a forced air supply
controller 52 by connector hoses 54 and 56.
The other end of the inner wall 24 is also provided with threads 57a for
mating engagement with the threads 57b provided on a cylindrical hollow
plastic inner tube 58. The inner tube 58 extends into the inner passage 28
thereby defining a central passage 60. The end of the inner tube 58
extending into the outer tube 12 terminates inwardly to form an opening 62
having a diameter less than that of the central passage 60. The other end
of the inner tube 58 extending beyond the shoulder 44 terminates in a
semi-spherical end section 64. The section 64 is provided with an aperture
66 and is coupled to the controller 52 by a connector hose 68. A pair of
nuts 70 and 72 are also provided. The nut 70 is secured to the shoulder 44
and the nut 72 is secured in position on the threads of the inner tube 58.
The threads 57a and 57b allow the inner tube 58 to be displaced linearly
with respect to the outer tube 12 as well be described.
The driving mechanism 16 is preferably formed from lightweight plastic
components and includes a turbine 74 located near the inner end of the
inner tube 58. The turbine 74 is formed having a diameter slightly less
than the diameter of the central passage 60 but greater than the diameter
of the opening 62. The turbine 74 is connected to an elongate hollow
driving rod 76 extending through the bores provided in the isolating plate
42 and the base plate 30 and out into the vessel. The driving rod 76 also
extends upwardly into the central passage 60 beyond the turbine 74 and is
rotatably coupled to three anchors, two 78 and 80 of which are shown. The
anchors are spaced by 120.degree. and are secured to the inner tube 58, to
permit rotational movement of the driving rod 76 while inhibiting linear
movement thereof. The end of the hollow driving rod 76 positioned in the
central passage 60 is provided with a closure flap 82 moveable between
open and closed positions.
The milling tool 18 is secured to the driving rod 76 exterior to the tube
12 and is flexible and leaf-shaped. Preferably, the tool 18 is formed from
stainless steel and includes shallow milling flutes 84 and airing slots
86. The distal end of the milling tool 18 is secured to the driving rod 76
by a coupling 88. The other end of the milling tool 18 is slidably engaged
with the driving rod 76 by a second coupling 90. The second coupling 90 is
dimensioned so that it is not capable of passing through the central bore
of the base plate 30. The driving rod 76 also has a portion of its
structure removed extending from inside the outer tube 12 to the coupling
88 to allow milled particles of the deposits to be removed from the vessel
into the apparatus 10 by suction.
One side of the outer tube 12 is provided with a guiding tube 92 for
supporting a guiding wire 94. The guiding tube and wire aid in the
placement of the apparatus 10 in the vessel. The outer tube 12 is also
surrounded by an inflatable balloon 96 which contacts a healthy arterial
vessel wall section when inflated to secure the apparatus 10 in the
vessel. A valve 100 positioned near the shoulder 44 allows air or a saline
solution to be infused into the upper portion 26a of the outer passage 26
so that the balloon 96 can be inflated.
The sensing device 20 includes first resistive wires 98 which are coupled
at one end to opposite ends of the balloon 96 and second resistive wires
102 which are coupled at one end to the coupling 90. The other end of the
first and second resistive wires 98 and 102 respectively are coupled to
potential voltage sources 104 which in turn are connected to the
controller 52. The controller 52 also includes a comparator 106 and an
indicator 108 operable to detect and inform the operator when the abnormal
deposit has been removed.
In operation of the angioplasty apparatus 10, the outer tube 12 is inserted
into the vessel so that the milling tool 18 is positioned near the deposit
to be removed. Thereafter, the balloon 96 is inflated with the air or
saline solution via the valves 100 and the upper portion 26a to secure the
apparatus 10 in the vessel and to bring the resistive wires 98 into
contact with the healthy arterial vessel wall section. Following this, air
is pumped into the central passage 60 of the inner tube 58 via the
controller 52 and connector hose 68 and is forced downwardly towards the
turbine 74. The turbine 74 which is securely affixed to the driving rod
76, rotates when the forced air passes therethrough and translates the
rotational motion to the driving rod 76 and hence, the milling tool 18.
The forced air is recirculated to the controller 52 via the inner passage
28, the drainage tubes 48 and 50 and the connector hoses 54 and 56.
As the milling tool 18 is rotated, it contacts and mills the abnormal
deposits locatedon the inner wall of the vessel since the deposit tissue
does not deform under contact with the milling flutes 84 due to its
rigidity. The milled particles of the deposit are drawn into the removed
structure of the driving rod 76 due to the pressure differential in the
vessel caused by the rotation of the milling tool 18 and the negative
pressure created in the passageways 28 and 60 due to the air flow. The
milled particles are forced upwardly through the driving rod 76 into the
lower portion of the outer tube 12 defined by the isolating plate 42 and
the base plate 30. The particles are then drawn through the opening 32 and
pass upwardly through the lower portion 26b of the outer passage 26.
The particles are then drawn into the inner passage 28 through the valve 40
which is held open by the recirculating air flowing in the inner passage
28. The particle and recirculating air mixture is conveyed to the
controller 52 as previously described and the mixture is filtered to
remove the particles before the air is recirculated into the central
passage 60.
When it is desired to reverse the direction of rotation of the milling tool
18, air is supplied into the inner passage 28 via the connector hoses 54
and 56 and drainage tubes 48 and 50 as opposed to the central passage 60.
Thus, the air is forced downwardly into the inner passage 28 and passes
upwardly through the turbine 74 and into the central passage 60. The
return air flow in the central passage 60 is conveyed to the controller 52
via the connector hose 68. The passage of air upwardly through the turbine
74 causes it to rotate in a direction opposite to that as previously
described.
The rotation of the turbine 74 in the opposite direction causes the driving
rod 76 and hence, the milling tool 18 to rotate to contact and mill the
deposits. Similarly, the rotation of the milling tool 18 forces the milled
particles to be drawn into the removed structure of the driving rod 76.
However, since the upward force generated by the rotation of the milling
tool 18 acts to open the closure flap 82 and since the air passing through
the central passage 60 flows in the same direction as the upward force,
the closure flap 82 opens, to allow the milled particles to pass into the
central passage 60. Thus, the particles removed by the milling tool 18 are
carried with the return flow of air in the central passage 60 and filtered
from the air by the controller 52 before the air is recirculated. this
design allows the milled particles withdrawn from the vessel to be
filtered by the controller 52 without the particles contacting the turbine
74 regardless of the direction of rotation of the turbine. Furthermore, by
alternating the direction of the air flow into and out of the passages 28
and 60, the milling tool 18 can be rotated alternately in opposite
directions. This alternate rotational operation increases the
effectiveness of the milling procedure.
To extend the edges of the milling tool 18 outwardly beyond the outer
diameter of the outer tube 12, the nut 72 is rotated, thereby rotating the
inner tube 58 to withdraw it from the outer tube. The resulting movement
of the inner tube 58 acts to retract the driving rod 76 and milling tool
18 into the outer tube 12. The retraction of the milling tool 18 causes
the coupling 90 to abut against the end plate 30 to prevent movement of
the milling tool 18 into the outer tube 12. However, since the coupling 90
is slidable along the driving member, as the inner tube 58 is further
withdrawn from the outer tube, the milling tool 18 is caused to expand in
a direction perpendicular to the longitudinal axis of the apparatus. As
the nut 72 is further rotated to withdraw the inner tube 58 from the outer
lumen 12, the milling tool 18 is forced to expand further beyond the outer
side of the outer tube 12. This allows the milling tool 18 to contact
smaller deposits or opeate in wider arterial vessels. The second nut 70 is
provided to set a limit for the release of the compressive forces placed
on the milling tool 18 to ensure that the milling tool 18 is not permitted
to resume a shape having a dimension which is inoperable for removing
deposits from the vessel walls.
To sense when the deposit has been removed from the vessel walls, the
voltage sources 104 located external to the outer tube 12 supply a
potential voltage to the resistive wires 98 and 102. The comparator 106
monitors the currents flowing in each of the circuits 98 and 102 and
compares the electrical resistance of the tissue contacted by the milling
tool 18 with that of the healthy tissue contacted by the circuits 98. The
presence of abnormal deposit tissue is detected, since the electrical
resistance of the deposit tissue is greater than that of healthy arterial
vessel tissue. When the abnormal deposit has been removed, the milling
tool 18 will contact healthy tissue and hence, the monitored electrical
resistance will be equal in both circuits 98 and 102 respectively. When
this occurs, the comparator 106 inhibits operation of the controller 52 to
prevent further milling in the vessel and provides an output to the
indicator 108. The indicator in turn provides an to the user that the
milling operation has been completed.
Referring now to FIGS. 4, 5 and 6, another angioplasty apparatus 10' is
shown. In this embodiment, like reference numerals will be used to
indicate like components with a "'" added for clarity. In this embodiment,
the inner wall 24 is not provided with an opening 32, but rather extends
to the driving rod 76' to form the isolating plate 42'. The outer tube 12'
is also provided with a divider 120 as opposed to an inner tube. The
divider 120 positions the drive mechanism 16' and separates the inner
passage 28' into a pair of parallel passages 122 and 124.
The drive mechanism 16' includes a pair of mating bevel gears 126 and 128.
The first gear 126 is disposed on a shaft 130. Opposite ends of the shaft
130 are connected to members 132 viq gearings 134 and extend upwardly to
engage with the divider 120. The ends of the shaft 130 are also coupled to
the driving rod 76' via a support frame 136. The gear 126 is positioned to
engage continuously with gear 128 and so that its axis of rotation is
substantially perpendicular to the driving rod 76'.
The second gear 128 is secured to the driving rod 76' and aligned so that
its axis of rotation is parallel to the longitudinal axis of driving rog
76'. The driving rod 76' similarly has a portion of its section removed,
extending from the milling tool 18' to the exterior side of the isolating
plate 42'. Apertures 138 are provided at the terminating ends of the lower
portion 26b' of the outer passage 26' to provide a path for the milled
particles from the vessel into the apparatus.
To rotate the milling tool 18', air is forced into one of passage 122 and
recirculated through the other passage 124, thereby causing the gear 126
to rotate. The rotation of gear 126 in turn rotates gear 128 and hence,
driving rod 76'. The milling tool 18' in turn is rotated, thereby allowing
the deposits to be milled and hence, removed from the vessel. The milled
particles of the deposit are drawn upwards through the driving rod 76' and
into the other passage 124 by way of the apertures 138, lower portion 26b'
of the outer passage 26' and the valve 40'. The particle and air mixture
is conveyed to the controller 52' and the particles are filtered from the
air in the manner previously described. To reverse the direction of
rotation of the milling tool 18', the air is forced into the other passage
124 and recirculated through the one passage 122, thereby reversing the
direction of rotation of the gears 126 and 128. As can be appreciated, by
alternating the direction of air flow into the passages 122 and 124, the
milling tool 18' can be rotated alternately in opposite directions.
Similar to the previous embodiment, the inner tube 58' and drive mechanism
16' can be displaced linearly with respect to the outer tube 12 to allow
the flexible milling tool 18' to be compressed longitudinally so that the
radial dimension of the milling tool increases. This is performed by
rotating the nut 72' to withdraw the divider 120 from the outer tube 12'
and in turn retract the drive mechanism 16' into the outer tube 12'. When
this occurs the shaft 130 of the gear wheel 126 moves upwardly along the
inner surface 24' via the bearings 134. The support frame 136 coupled
between the shaft 130 and the driving rod 76' in turn moves the gear wheel
128 and the driving rod 76' in the same direction. Thus, in a similar
manner, the milling tool 18' is compressed to extend its radial dimension.
As should be appreciated, the apparatus 10' of this embodiment is also
positioned in the vessel via an inflatable balloon 96' and the removal of
the deposit tissue is monitored by a sensing device 20' identical to that
described previously.
FIGS. 7a and 7b show yet another embodiment of an angioplasty apparatus.
Similarly, like reference numerals will be used to indicate like
components with "200" added for clarity. In this embodiment the outer tube
212 is rectangular in shape and is provided with an integrally formed base
plate 230. The plate 230 is provided with the central bore for the passage
of the driving rod 276. The inner wall 224 is also sealed to the base
plate 230, thereby sealing the lower portion 226b of outer passage 226
from the inner passage 228. Electromagnets 160 are provided in the lower
portion 226b and surround the driving mechanism 216. The electromagnets
are coupled to an AC power source (not shown) located in the controller
for energizing the magnets 160. Provided in the outer tube 212 is a
rectangular-shaped inner tube 258. A rotating magnetic rotor 164 is
provided in the inner tube and is engaged with the driving rod 276. The
inner tube 258 includes a base 259 having a control bore for allowing the
driving rod 276 to extend beyond the base while sealing the lower end of
the central passage 260, from the inner passage 228.
When the electromagnets 160 are energized via the power source, the rotor
164 is rotated in a direction dependent on the direction of the magnetic
fields, thereby rotating the milling tool 218. Thus, the milling tool 218
rotates alternatively in opposite directions when energized with the AC
supply voltage. The deposit material milled by the millting tool 218 is
conveyed through the removed structure of the driving rod 276 and into the
controller by way of the inner passage 228. The controller although not
shown in this embodiment acts solely as a suction device since the
rotation of the driving mechanism 216 is electrically powered and is not
dependent on recirculating air.
It should be noted that the inner tube 258 can also be displaced linearly
with respect to the outer tube 212 to expand the milling tool 218 in the
same manner described for previous embodiments provided that the rotor 164
remains in the rotating field created by the electromagnets 160.
Referring now to FIGS. 8a to 8c, 10 and 11 still yet another angioplasty
apparatus 410 is shown. In this embodiment, like reference numerals will
be used to indicate like components with "400" added for clarity. The
apparatus 410 uses as the drive mechanism 416, a piston 170 coupled to the
driving rod 476. The hollow driving rod 476 terminates in a twisted wire
pair 172 which permits bi-directional rotation of the milling tool 418.
The piston 170 separates the inner passage 428 into lower and upper
portions and is coupled on one side to the hollow driving rod 476. The
driving rod 476 passes through the lower portion of the tube 412 to engage
with the lower ring 186a of a coupling 186, the lower ring 186a is also
being secured to the base 430. The milling tool 418 is rotatably coupled
at one end to the top ring 186b of the coupling 186 and secured at the
other end thereof to a second coupling 188 mounted on the twisted pair 172
and thus, rotates as it advances along the pair when the driving rod 476
is linearly reciprocated by the piston 170. A central tube 178 extends
from the lower portion of the outer tube, up through the driving member
476 and piston 170 and is connected to the controller 452 to allow the
particles milled by the milling tool 418 to be removed from the vessel by
suction. An access tube 190 is also provided to allow the upper portion of
the tube 412 to be pressurized in order to reciprocate the piston 170. A
second tube 191 is provided to allow the balloon 496 to be inflated by the
infusion of air or saline.
To drive the piston 170, the upper portion of the tube 412 is pressurized
by air or saline solution supplied by the controller 452 via the access
tube 190. The air is alternatively withdrawn and applied into the upper
portion and provides the force for reciprocating the piston. The piston
170 in turn linearly drives the driving rod 476 to extend beyond the
milling tool 418 so that the coupling 188 rotates around the twisted pair
172 as the pair advances, thereby causing the milling tool 418 to rotate.
When the piston 170 is drawn into the tube 412, the engagement between the
coupling 188 and the twisted pair 172 allows the milling tool 484 to
rotate in the opposite direction. As shown in FIGS. 9a to 9c, the forced
air piston drive mechanism is replaced by an electromagnetic drive
mechanism, the operation of which is known in the art and will not be
described here.
FIGS. 10a to 10f show the milling tool 418 and the twisted pair 172 in more
detail. The twisted pair 172 is also provided with abutment pegs 184 for
limiting the linear movement of the driving rod 476 with respect to the
milling tool 418 and for providing an abutment means. The milling tool 418
can also include an "umbrella" 180 secured to the driving rod 476 and
capable of opening upon movement of the twisted pair 172 towards the
milling tool 418. The umbrella 180 is provided with teeth 182 for cutting
the deposit and is rotatable with the milling tool 418. Thus, the milling
tool 418 can provide further cutting of the deposit in a plane
substantially perpendicular to the axis of the driving rod 476. To expand
the edges of the milling tool 418, the abutment pegs 184 are brought into
further engagement with the tool 418 thereby compressing the tool since
the milling tool is secured to the removable rings 186b at one end.
Referring to FIGS. 12 and 13, still yet further embodiment of the
angioplasty apparatus are shown. In these embodiments, the drive mechanism
is similar to that shown in FIGS. 8 and 9 except the milling tool 418 is
secured to the reciprocating driving rod 476 rather than being rotatably
secured to the base 430 by the coupling 186. Thus, in these embodiments,
the milling tool 418 is linearly reciprocated with the driving rod 476 and
alternately rotates in opposite directions. This allows the milling tool
418 to extend further into the vessel unlike the milling tool 418 in the
embodiment of FIGS. 8 and 9. Furthermore, the milling tool 418 can be
compressed so that the outer edges extend beyond the outer edge of the
tube 412 by moving the milling tool 418 so that it abuts against the base
plate 430 while still being rotated. It should be apparent that each of
the above embodiments described include a sensing device similar to that
described in FIG. 1 for monitoring the removal of deposits from vessel
tissue. It should also be appreciated that a balloon is used to secure the
apparatus in the vessel and that an appropriate controller is used to
provide forced air, an electrical power supply or simply suction depending
on which embodiment of the angioplasty aparatus is being used.
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