U.S. patent application number 09/750149 was filed with the patent office on 2001-05-10 for method and apparatus for mechanical transmyocardial revascularization of the heart.
Invention is credited to Mueller, Richard L..
Application Number | 20010001124 09/750149 |
Document ID | / |
Family ID | 24866506 |
Filed Date | 2001-05-10 |
United States Patent
Application |
20010001124 |
Kind Code |
A1 |
Mueller, Richard L. |
May 10, 2001 |
Method and apparatus for mechanical transmyocardial
revascularization of the heart
Abstract
An apparatus for creating revascularization channels in tissue,
such as the myocardium of the heart, mechanically cuts the channels
using a hand piece with easily removable cutting tip assemblies
having angled, sharpened edges to allow rapid tip replacement. The
cutting tip assembly has an inner needle within an outer hollow
needle with each needle attached to the hand piece for independent
rotation and axial movement. The inner needle may be hollow, or
formed with a pointed tip, and may rotate counter to the outer
needle to enhance gripping and storage of the tissue excised by the
outer needle. The hand piece may attach a cylindrical magazine of
cutting tip assemblies or one cutting tip assembly. The cutting tip
assembly may be heated to provide thermal damage to the heart
muscle during the creation of the channel, providing some of the
advantages of the laser method of TMR.
Inventors: |
Mueller, Richard L.;
(Sunnyvale, CA) |
Correspondence
Address: |
R. Danny Huntington, Esq.
BURNS, DOANE, SWECKER & MATHIS, L.L.P.
P. O. Box 1404
Alexandria
VA
22313-1404
US
|
Family ID: |
24866506 |
Appl. No.: |
09/750149 |
Filed: |
December 29, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09750149 |
Dec 29, 2000 |
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09248782 |
Feb 12, 1999 |
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09248782 |
Feb 12, 1999 |
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08713531 |
Sep 13, 1996 |
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5871495 |
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Current U.S.
Class: |
606/180 ;
606/167; 606/184 |
Current CPC
Class: |
A61B 17/32002 20130101;
A61B 2010/0208 20130101; A61B 17/320016 20130101; A61B 2018/00392
20130101; A61B 10/04 20130101; A61B 10/0275 20130101; A61B 17/32053
20130101; A61B 2017/00247 20130101; A61B 2017/00292 20130101; A61B
2017/306 20130101 |
Class at
Publication: |
606/180 ;
606/167; 606/184 |
International
Class: |
A61B 017/32; A61B
017/14 |
Claims
What is claimed is:
1. An apparatus for creating channels in tissue appropriate for
improving blood flow and tissue regeneration, the apparatus
comprising: a generally cylindrical cutting assembly defining an
axis; tissue storage means within the cutting assembly for holding
a core of tissue during and following mechanical cutting of tissue
by the cutting assembly; and means for advancing the cutting
assembly into the tissue.
2. The apparatus of claim 1 wherein the cutting assembly comprises
at least one needle having a hollow internal bore and a distal tip,
the distal tip defining a sharpened edge disposed at a specified
angle to the axis and surrounding the hollow internal bore.
3. The apparatus of claim 2 wherein the means for advancing the
cutting assembly comprises a handpiece for attachment of the
cutting assembly thereto, the handpiece having a rotation mechanism
for rotating the cutting assembly and a translation mechanism for
moving the cutting assembly axially.
4. The apparatus of claim 3 further comprising attachment means for
removably connecting the cutting means to the handpiece.
5. The apparatus of claim 4 wherein the handpiece is powered for
operating at least the rotation mechanism and the attachment means
is at least one linkage connected to the cutting assembly and
releasably mounting to the handpiece.
6. The apparatus of claim 5 wherein the handpiece comprises a
housing for enclosing at least one motor having at least one output
shaft; gear means attached to the at least one output shaft and
operatively associated with the linkage, the gear means advancing
and rotating the at least one needle axially into the tissue;
controller means connected to the at least one motor for processing
a preselected sequence of advancement and rotation of the at least
one needle; and at least one actuator means for activating the
motor.
7. The apparatus of claim 1 further comprising means for heating
the cutting assembly.
8. The apparatus of claim 4 comprising an inner needle disposed
within a hollow outer needle, the inner and outer needles each
defining a substantially coincident lateral axis to allow
relatively lateral translation between the inner needle and the
outer needle, the attachment means enabling independent rotation
and axial movement of the inner needle with respect to the outer
needle.
9. The apparatus of claim 8 wherein the inner needle defines a
hollow internal bore and a distal tip defining a sharpened edge
disposed at a specified angle to the axis and surrounding the
hollow internal bore.
10. The apparatus of claim 8 wherein the inner needle is shaped to
define a drill tip configuration.
11. The apparatus of claim 8 wherein the inner needle is shaped to
define a screw tip configuration.
12. The apparatus of claim 8 wherein the inner needle is hollow and
defines a cylindrical outer wall, the tissue storage means is a cut
away portion in the outer wall of the inner needle, and the inner
needle defines a piercing tip at a distal end thereof.
13. The apparatus of claim 8 wherein the means for rotating
includes rotation of the inner needle counter to the outer
needle.
14. The apparatus of claim 5 wherein the hand piece further
comprises vacuum means for applying a counterforce to cutting
forces of the cutting assembly.
15. The apparatus of claim 2 wherein the storage means is the
hollow internal bore of the at least one needle.
16. The apparatus of claim 4 for creating channels in cardiac
muscle appropriate for transmyocardial revascularization, the
apparatus further comprising a removable magazine attached to the
handpiece, the magazine holding a plurality of cutting assemblies
for automatically and rapidly rotating an unused cutting assembly
into position within the handpiece to create each channel.
17. The apparatus of claim 16 wherein the cutting assembly further
comprises a piercing tool for creating a small entry hole through
epicardium to allow introduction of the at least one needle into
myocardium.
18. The apparatus of claim 2 for creating channels in cardiac
tissue appropriate for transmyocardial revascularization wherein
the cutting assembly comprises a single needle having a hollow
internal bore for retaining and storing excised cardiac tissue, the
needle having a tapered distal tip defining a sharpened edge
disposed at a specified angle to the axis and surrounding the
hollow internal bore, the cutting assembly further comprising
support means surrounding the tapered needle for supporting the
cutting tip assembly in contact with the cardiac tissue during
creation of the channels.
19. A method for creating channels in the wall of the cardiac
muscle appropriate for transmyocardial revascularization, the
method comprising: rotating an inner needle disposed within a bore
of an outer needle about the inner needle's lateral axis; orienting
the lateral axis of the inner needle to insert with the surface of
the external heart wall; translating the inner needle laterally
along said lateral axis until the inner needle cuts partway into
the heart wall; stabilizing the inner needle in the partial cut
heart wall by ceasing rotation thereof; rotating the outer needle
about its lateral axis, the outer needle being disposed such that
the lateral axis of the inner needle and the lateral axis of the
outer needle are substantially coincident, the disposition of the
inner needle within the bore of the outer needle allowing relative
lateral translation between the inner needle and the outer needle;
translating the outer needle laterally along the lateral axis of
the outer needle until the outer needle cuts the desired depth of
channel into the heart wall and the excised tissue is held by the
inner needle; and laterally withdrawing the inner needle and the
outer needle.
20. The method of claim 19 further comprising the step of heating
the inner and outer needles to a temperature of at least 60 degrees
Celsius.
21. The method of claim 20 further comprising the step of applying
a suction counter force while rotating and advancing the outer
needle.
22. The method of claim 19 further comprising the step of rotating
the inner needle while rotating the outer needle, the inner needle
being rotated in a direction counter to a direction of rotation of
the outer needle.
Description
FIELD OF THE INVENTION
1. This invention relates to the field of surgical interventions
for correction of coronary disease, and more particularly to the
methods and devices for transmyocardial revascularization of the
heart.
BACKGROUND OF THE INVENTION
2. Heart disease is a significant health problem which has been the
subject of substantial medical study. Bypass surgery has become
commonplace; yet such surgery may be unavailable to many patients,
either because of the nature of the occlusions or the physical
condition of the patient.
3. One promising alternative technique for treating such cases is
known as trans-myocardial revascularization (TMR). Although this
technique was considered as early as the work of Dr. C. Beck "the
Development of a New Blood Supply to the Heart By Operation",
Annals of Surgery, Vol. 102, No. 5 (11/35) pp. 801-813, the method
was not extensively studied until the work of Dr. M. Mirhoseini and
M. Cayton, an example of which is found in "Lasers in
Cardiothoracic Surgery in Lasers in General Surgery (Williams and
Williams; 1989) pp. 216-223.
4. An early device to perform TMR is described in Aita et al., U.S.
Pat. No. 5,380,316, issued Jan. 10, 1995. In the procedure
described in that patent, a number of channels are formed through
the myocardium between the ventricle and the exterior of the heart
through the epicardium and myocardium by means of a laser
apparatus. These channels were approximately 1.5 mm-2.0 mm in
diameter and approximately 1 to 3 cm deep. Clinical tests have
demonstrated that such channels facilitate revascularization of the
heart muscle and recovery of heart function.
5. Unfortunately, this technique has some attendant difficulties.
The laser equipment for performing such procedures is large and
expensive and may be unavailable to smaller and more remote medical
facilities. Some patients may therefore find it difficult to gain
access to a properly equipped medical facility when treatment is
needed.
6. One alternative to the use of lasers would be to use a
mechanical cutter to produce the channels. Unfortunately, as noted
in the Aita et al. patent, prior art methods of mechanical piercing
and cutting of the heart wall produce tearing of the tissue. Such
tearing leads to fibrosis, which combined with the problems of
maintaining clear, clean channels, seriously diminishes the
effectiveness of the TMR treatment produced by such methods. Hence,
such prior art mechanical piercing does not adequately facilitate
rapid and clean healing of channels.
7. Another alternative approach, melting of the myocardium by hot
probes, has proven unsatisfactory, partly because there is no
mechanism for removal of melted material from the channel.
8. It would therefore be desirable to produce clear, clean channels
using relatively inexpensive and easily transportable systems,
which may be deployed in remote locations.
SUMMARY OF THE INVENTION WITH OBJECTS
9. Broadly, an advantage of the present invention to provide an
apparatus and method for producing viable channels suitable for TMR
without the use of lasers.
10. More specifically, an advantage of the present invention to
provide an apparatus and method for mechanically performing TMR
without excessive tearing or other complications which cause
blockage of the created channels.
11. It is a further advantage of the present invention to provide
an apparatus and method for mechanically performing TMR without a
requirement for large, expensive equipment.
12. Yet another advantage of the present invention is to provide a
hollow cutting device, which may or may not be heated, for
mechanically cutting and removing myocardial tissue to create
channels in the myocardium.
13. Still one more advantage of the present invention is to provide
a hand held tool for deploying cutting devices for non-laser TMR
procedures.
14. The present invention comprises a method and apparatus for
mechanically performing transmyocardial revascularization (TMR).
Although the invention may be implemented in a variety of
embodiments, several of which are illustrated herein, all require
an apparatus with a special cutting tip assembly, preferably an
easily removable cutting tip assembly which would allow rapid
replacement to permit several channels to be created in a
relatively short period of time. This cutting tip assembly has
means for supporting the assembly in location on the heart wall
while in operation. In several of the embodiments shown herein, the
support means may include suction to assist in clean, complete
removal of the material excised from the heart wall by the cutting
tip assembly during formation of channels. In all embodiments there
also is a mechanical means present to remove that material which is
to be excised to form the channel. Preferably, the cutting tip
assembly is removably mounted to a hand piece with an actuator to
deploy, rotate, and remove the cutting tip assembly. The hand tool
may accommodate one or more cutting tip assemblies.
15. The cutting tip assembly optionally may be heated to provide
thermal damage to the heart muscle during the creation of the
channel, providing some of the advantage of the laser method of
TMR. Such heating may be provided by placing the cutting tip
assembly in a specially designed heater base which permits rapid
connection of the assembly to the remainder of the apparatus while
the cutting tip assembly is still in the heater. In this way the
cutting tip assembly may be maintained at optimal temperature until
the apparatus is ready to be deployed.
16. These and other objects, advantages and features of the present
invention will be apparent to those skilled in the art from the
following detailed description and the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
17. FIGS. 1A-1E illustrate a presently preferred method and
apparatus according to the present invention, utilizing a cutting
tip assembly comprising two concentric rotatable needles.
18. FIGS. 2A-2D illustrate a second preferred method and apparatus
according to the present invention, utilizing a cutting tip
assembly comprising a single hollow needle within a support
means.
19. FIGS. 3A-3C illustrate additional aspects of inner needles of
cutting tip assemblies comprising two needles. FIG. 3A illustrates
a drill style inner needle; FIG. 3B illustrates a screw style inner
needle; and FIG. 3C illustrates an inner needle defining a side cut
and a piercing tip.
20. FIG. 4 is a perspective view of a mechanism for mounting a
cutting tip assembly of the present invention to a hand piece for
rotation and axial movement.
21. FIG. 5 is a side view of a preferred hand piece having a
cylindrical magazine, shown linearly for purposes of illustration
only, holding multiple cutting tip assemblies.
22. FIG. 6 is a side view of another aspect of a hand piece for
performing mechanical TMR and having a single, detachable cutting
tip assembly.
23. FIG. 7 is a front view of a heating block for cutting tip
assemblies.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
24. While a variety of embodiments of the present invention are
disclosed herein, one exemplary presently preferred embodiment is
illustrated in FIGS. 1A through 1D. FIGS. 1A through 1D each
represent a different stage in the process of creating a channel 18
in the myocardium 10, which has an outer wall (epicardium) 12 and
an inner wall (endocardium) 14.
25. FIG. 1A illustrates that the apparatus of this embodiment of
the present invention has a cutting tip assembly 40 with an inner
cylindrical needle 20, which has a tubular hollow internal bore 22
within its body 24. Because inner needle 20 is cylindrical, it has
a lateral axis 28. Inner needle 20 has a sharpened edge 26, which
may be made sharp through use of a variety of geometries (e.g.,
beveled inward, beveled outward). A presently preferred cutting
edge defines an angle less than 45 degrees, and preferably less
than 30 degrees, from the lateral axis 28. The cutting edge is
sharpened using conventional techniques used in, for instance, the
production of razor blades. Use of a newly sharpened cutting edge
for each channel is recommended to reduce drilling trauma, tissue
wrapping forces, and create cleanly excised channels.
26. As shown in FIG. 1E, the inner needle 20 also may have a
sharpened retractable piercing tool 42 with a sharped point 44 for
making a small, initial incision through the epicardium, as better
described below. The piercing tool 42 moves upwardly and downwardly
as shown by the directional arrow in FIG. 1E with such movement
being controlled conventionally using manual or automatic control
methods and apparatus.
27. FIGS. 1A-1E further illustrate that the cutting tip assembly 40
has an outer cylindrical needle 30, which has a tubular hollow
internal bore 32 within its body 34. Again, because outer needle 30
is cylindrical, it has a lateral axis 38. Outer needle 30 has a
sharpened edge 36, which also is made sharp through use of a
variety of geometries (e.g., beveled inward, beveled outward) using
the sharpening techniques discussed above, and may define an angled
cutting edge as described in connection with inner needle 20.
28. Outer needle 30 is disposed relative to inner needle 20 roughly
surrounding inner needle 20 (which may also be viewed as inner
needle 20 being disposed within the internal bore 32 of outer
needle 30). The lateral axis 28 of inner needle 20 and lateral axis
38 of outer needle 30 need to be substantially coincident; such an
arrangement of needles should allow relative lateral translation
between inner needle 20 and outer needle 30, as well as
differential rotation of the two needles, as shall be described
below.
29. Alternative aspects of the inner needle are shown in FIGS. 3A
and 3B. In FIG. 3A, the inner needle is formed as a sharped,
spiraled drill 200 which may be rotated downwardly with the outer
needle 134. The drill needle configuration 200 defines a sharpened
piercing tip 440 serving the same purpose as point 44 in FIG. 1E
and further functions to pull excised tissue upwardly into the
hollow outer needle 30. The drill needle 200 may or may not be
rotated at the same speed and same time as the outer needle 30. In
FIG. 3B, the inner needle 200', is formed as a screw mechanism 200'
which may be rotated to advance into myocardial tissue 10. The
screw mechanism 200' may be held stationary within the myocardium
10 as the outer needle 30 is rotated and moved downward to cut a
channel through the myocardium 10 and, preferably, through the
endocardium 14. the screw mechanism 200' also includes a pointed
piercing tip 440'. Removal of the screw mechanism 200' (or the
drill needle 200) and the outer needle 30 causes removal of the
excised myocardial tissue which is held by the screw or drill
mechanism 200, 200' within the hollow outer needle 30. FIG. 3C
illustrates an additional aspect of an inner needle 200" which
defines a side cut aperture 50 for holding excised tissue and a
sharpened piercing tip 440".
30. Any of the inner and outer needle arrangements shown in FIGS.
1A-1E and 3A-3D enable initial piercing of the epicardium utilizing
the point 44 in conjunction with FIGS. 1A-1E or the piercing tips
(440, 440', 440") of the inner needle in conjunction with FIGS.
3A-3C to create a small hole for entry into the myocardium.
Alternatively, the smaller bore inner needle 20 may be used to
create the initial opening. The creation of a small entry point is
preferred to decrease bleeding at the epicardial surface and reduce
any tendency for the formation of adhesions between the epicardium
and the pericardial sac. The inner needle (20, 200, 200', or 200")
is advanced into the myocardium and stabilizes the entire cutting
tip assembly by embedding the inner needle into myocardium. The
embedded inner needle serves as an anchor to secure the assembly to
the beating heart while the outer needle is rotated and advanced.
The inner needles described above also hold the excised tissue in
place, prior to retracting that tissue, and ensure that excised
tissue is evenly distributed within the internal bore of the outer
needle as the outer needle is advanced and retracted.
31. Another preferred embodiment of the present invention having a
cutting tip assembly 400 with a single needle 402 is illustrated in
FIGS. 2A through 2D. Again, FIGS. 2A through 2D each represent a
different stage in the process of creating a channel 18 in the
myocardium, or heart wall 10, which has an outer wall 12 and an
inner wall 14.
32. A support means 100 with a tubular hollow internal bore 102
within its body 104 is placed against outer heart wall 12. The
support means 100 may be a generally disk shaped block with a
frictional contact surface, preferably with vacuum apparatus 106 to
assist in removal of excised tissue and to provide a counter force
to the cutting tip assembly 400. Because the internal bore 102 of
the support means is cylindrical, it has a lateral axis 108.
Alternatively, the support means may be a wall surrounding an
aperture for inserting the cutting tip assembly into a hand piece,
to be described below.
33. The tapered needle single needle 402 has a hollow internal bore
404 within its body 406. Again, because tapered needle 402 is
cylindrical, it has a lateral axis 408. Tapered needle 402 has an
edge 406, which may be made sharpened and angled as described in
connection with the FIG. 1A-1D and 3A-3D embodiments above.
34. Tapered needle 402 is disposed relative to support means 100 by
being disposed within the internal bore 102 of support means 100.
The lateral axis 108 of internal bore 102 and lateral axis 408 of
tapered needle 400 need to be substantially coincident; such an
arrangement of needles should allow relative lateral translation
between tapered needle 402 and internal bore 102, as well as
rotation of tapered needle 402. A piercing tool, such as tool 42
shown in FIGS. 1A-1E also may be used within the bore of tapered
needle 402.
35. In order for the various cutting tip assemblies described above
to function as described herein, each cutting tip assembly
preferably is linked to a hand held device, such as the hand pieces
85 and 850 shown in FIGS. 5 and 6. Hand pieces 85, 850 allow
automatic advancement and rotation of the cutting tip assembly.
36. FIG. 4 illustrates an example of linkages 70, 71 which may be
used to connect the cutting tip assemblies to the hand pieces. Dual
linkages 70, 71 separately mount an inner needle 20 and an outer
needle 30 to allow independent rotation and movement of the inner
and outer needles. The inside diameter of linkage 71 is larger than
the inside diameter of linkage 70 to facilitate loading the
linkages into the hand piece and to allow reciprocation of inner
needle 20 within outer needle 30. Because inner needle 20 is
disposed within outer needle 30, its linkage 71 may be disposed
within the linkage 70 for outer needle 30. Preferably, the linkages
70, 71 fit into mating cavities in the hand pieces, although other
conventional mounting arrangements may be used. The linkages 70, 71
may snap mount within the mating cavities of the hand pieces to
enable new, unused cutting tip assemblies to be quickly and easily
connected to the hand pieces. Such drives and their linkages must
be capable of providing independent rotational and translation
motion for both needles of cutting tip assembly 40. Hence, four
separate degrees of freedom, two rotational and two translational,
must be provided for cutting tip assemblies having an inner and
outer needle. Only one linkage need be provided for the single
needle embodiment of FIG. 2. In this FIG. 2 embodiment, the drive
and its linkage must be capable of providing independent rotational
and translation motion for the tapered needle 402. Hence, two
separate degrees of freedom, one rotational and one translational,
must be provided for tip 400 of this preferred embodiment.
37. Referring now to FIGS. 5 and 6 showing the hand pieces 85 and
850, the linkages 70, 71 for the two needle cutting tip assemblies
are independently connected to, respectively, reciprocation
mechanisms 74, 75 and motor drives 76, 77 to provide both axial
movement and rotation. The motor drives 76, 77 may be gear motors
operatively connected to a controller (not shown). The controller
is activated when the operator pushes actuator 78, such as one or
more triggers or buttons, to activate the motor drives 76, 77. The
motor drives 76, 77 may be powered by a battery (not shown) and the
controller operates to regulate the motor drives to correctly
sequence channel creation. Rotating output shafts 79 of the motors
76, 77 engage gear mechanisms 81 which rotate and engage the inner
and outer needles 20, 30 and cause rotation thereof.
38. At the same time as rotation is occurring as described above,
lead screws 83 rotate in response to operation of reciprocation
mechanisms 74, 75 thereby causing linear movement of piston 91. As
piston 91 moves linearly towards linkage 70, inner needle 20
advances in an axial direction because it is operatively connected
to reciprocation mechanisms 74, 75 by a bracket 89. Further
advancement of the piston 91 causes the outer needle 30 to advance
in an axial direction when the piston 91 engages linkage 71. The
stroke length of the piston is controlled using mechanical or
electrical stops on the lead screws. Alternatively, stepper motors
may be used to advance and retract the needles thereby allowing
control of the stroke of the piston.
39. Referring now to FIG. 5, multiple cutting tip assemblies 40 are
disposed within a cartridge 80 which is removably mounted to the
hand piece 85. The cartridge 80 preferable is generally cylindrical
and defines a plurality of apertures for insertion of the cutting
tip assemblies 40. FIG. 5 shows the cutting tip assemblies 40 in a
linear arrangement for the purpose of illustration only. An
advancement mechanism 82 includes a motor drive 84 which, upon
activation of the actuator 78, causes rotation of the cartridge 80
to introduce a new cutting tip assembly 40 into aperture 87. As the
new cutting tip assembly 40 is rotated into position, the gear
motors 76, 77 cause reciprocation and rotation of the cutting tip
assembly 40 as described above. Following creation of each channel
and movement of the hand piece to a different location on the
heart, the trigger is again pressed to reactive the sequence. Any
conventional rotational mechanism may be used to rotate the
cartridge 80.
40. FIG. 6 is a hand piece 850 for snap mount attachment of a
single cutting tip assembly which may be easily disconnected prior
to snap mounting a new tip into place. The FIG. 6 embodiment
operates the cutting device in the same manner as described in
connection with the FIG. 5 embodiment.
41. The method of the present invention using a hand piece 85 or
850 with a cutting tip assembly having an inner and outer needle
may now be understood. FIG. 1E illustrates that, when activated,
piercing tool 42 moves downwardly below the edge of inner needle 20
to create an inital hole through the epicardium prior to retraction
upwardly within inner needle 20. FIG. 1A illustrates that, when
actuated by trigger 78, inner needle 20 is rotated about its
lateral axis 28. Lateral axis 28 of inner needle 20 is held
substantially perpendicular to the exterior surface 12 of the
heart. Movement of the piston 91 causes the inner needle to be
translated laterally along lateral axis 28 until sharpened edge 26
of inner needle 20 enters the epicardium 12 through the initial
hole and travels partway into the myocardium 10. In this way a core
16 of tissue from the myocardium 10 extends into the tubular hollow
internal bore 22 of inner needle 20.
42. FIGS. 1B and 1C illustrate the next step in this method. Inner
needle 20 is stabilized in location by ceasing rotation of inner
needle 20 and holding inner needle 20 stationary as piston 91
reaches its maximum stroke for inner needle 20. This stabilization
may be improved by use of a vacuum applied to tubular hollow
internal bore 22 to provide suction upon core 16 to hold it in
place during further cutting. As shown in FIG. 6, the piston 91 may
be hollow for attachment of a vacuum line 93 communicating with the
hollow internal bores of, at least, the inner needle.
43. Next, outer needle 30 is actuated to rotate about its lateral
axis 38 and is translated laterally along lateral axis 38, with
sharpened edge 36 entering the hole through the epicardium 12 and
passing into the myocardium 10 when the piston 91 engages outer
needle linkage 71. This translation is continued until outer needle
30 cuts the desired depth of channel into the myocardium 10. In
this manner the remainder of the heart tissue to be excised is
located within hollow internal bore 32 of outer needle 30. Ideally,
this will be a channel that extends completely through the
endothelium 14, thus creating a channel extending into the
ventricle.
44. Finally, FIG. 1D illustrates that cutting tip assembly 40,
including both inner needle 20 and outer needle 30, is removed from
the myocardium 10 after lateral withdrawal of both needles,
creating a channel 18. Core 16 of heart wall 10 is also removed
cleanly if channel 18 extends completely through the endothelium
15.
45. By providing multiple degrees of freedom of motion to the
cutting tip assemblies, the inner needle may be rotated for several
turns in a first direction while the advancing outer needle rotates
in the opposite direction. Rotation of the inner needle 20 counter
clockwise to the direction of rotation of the outer needle 30
compresses the excised tissue and holds it away from the outer
needle 30. The excised tissue attached to the inner needle is
twisted by the counter rotation thereby reducing its diameter to
enhance channel formation and free the excised tissue from the
interior wall of outer cutting needle 30. Additionally, counter
rotation with the application of counter cutting forces by an
applied vacuum is particularly useful to achieve a clean cut
through the endothelium without leaving a flap or ragged edge.
46. The method of the present invention using the FIG. 2 preferred
embodiment may now be understood. FIG. 2A illustrates that support
means 100, or distal tip of a hand piece 85 or 850, is placed
adjacent to the exterior surface 12 of heart wall 10, with internal
bore 102 substantially perpendicular to that surface. Tapered
needle 402 is disposed within internal bore 102, or within the bore
of the hand piece. FIGS. 1B and 1C illustrate the next step in this
method. Tapered needle 402 is rotated about its lateral axis 408.
Then, tapered needle 402 is translated laterally along lateral axis
108, with sharpened edge 406 cutting through heart wall 10,
creating a core 16 of heart wall 10 contained within internal bore
404 of tapered needle 402.
47. This translation is continued until tapered needle 402 cuts the
desired depth of channel into heart wall 10. In this manner the
remainder of the heart tissue to be excised is located within
hollow internal bore 404 of tapered needle 402. Ideally, this will
be a channel that extends completely through the inner heart wall
14, thus creating a channel extending through heart wall 10.
48. Finally, FIG. 2D illustrates that tapered needle 402 is
laterally removed from heart wall 10, creating a channel 18. Core
16 of heart wall 10 is also removed cleanly if channel 18 extends
completely through inner heart wall 115, particularly if a vacuum
is applied. The tapered configuration of the needle 402 holds the
excised tissue and prevents it from exiting through the narrower
distal tip when the needle 402 is withdrawn.
49. The creation of viable channels using any of the cutting tip
assemblies, with or without the hand pieces discussed above, is
greatly facilitated by first heating the cutting tip assemblies to
a temperature of at least 60 degrees Celsius. This provides thermal
damage to the heart wall 10, in addition to the thermal damage
created from frictional engagement of the cutting tip assembly,
which has been found to be efficacious in production of viable
channels, and simulates the thermal shock of the prior art laser
methods. The cartridge embodiment of FIG. 5 may include a separate
heating element (not shown), such as a conventional thermal band
(not shown) to ensure that each cutting tip assembly is heated as
it is rotated into place. Alternatively, a plurality of cartridges
80 may be heated in an oven (not shown) and attached with a snap
lock or quick disconnect mechanism to the hand piece. Heated
cutting tip assemblies for the FIG. 6 embodiment may be
accomplished using a heating block 120 as shown in FIG. 7. The
heating block 120 holds a plurality of cutting tip assemblies which
snap mount into the hand piece 850. The aperture in the hand piece
may be slipped over the linkage at the top of the cutting tip
assembly within the heating block and snapped into place without
handling the cutting tip assembly.
50. As will be understood by those familiar with the art, the
present invention may be embodied in other specific forms without
departing from the spirit or essential characteristics thereof. The
scope of the present invention is therefore limited only by the
scope of the claims appended hereto.
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