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Surgeries to treat disease in the heart, particularly blockages in coronary
vessels, are becoming increasingly common and necessary to treat
atherosclerosis and other conditions causing reduced blood flow to the
muscles of the heart. For many years, surgeons have performed "open heart"
surgery to repair defects in the muscles of the heart and the associated
cardiovascular system. As these procedures have become more common and
more costly, a need has developed for techniques to make cardiac surgical
procedures less traumatic to the patient. The necessity of attaching a
surgical patient to a cardiopulmonary bypass (CPB) apparatus is a primary
contributor to the trauma inherent in traditional procedures. To attempt
to alleviate the trauma and side effects of CPB, surgeons have begun
performing cardiac surgeries without stopping the heart. To successfully
perform such surgery, several challenges must be met. One particular
problem confronting the surgeon who operates on the beating heart is the
difficulty in performing extremely delicate surgical procedures while the
contractions of the heart muscles cause the surface of the heart to
continuously move.
To attempt to restrict the motion of heart at the particular area where the
surgeon is working, the surgeon may pass at least a pair of sutures
through the exterior tissue layers of the heart. By pulling the sutures in
opposite directions, the tissue is stretched, and the motion caused by the
contractions of the heart muscles is reduced or partially compensated.
This technique is not completely effective in restricting the natural
motion of the heart and requires extra time to place the sutures, and,
additionally, may cause damage to the cardiac tissue when the sutures are
placed or manipulated. Preferably, the surgeon would be able to fix the
motion of the cardiac tissue containing or adjacent to an area where
surgery is to be performed without the need to attach or manipulate
additional sutures. The ability to fix the position of the cardiac tissue
in a selected region of the heart would permit the surgeon to perform
delicate surgical procedures on the beating heart while the portion of the
heart on which the surgery is performed remains substantially motionless
throughout the procedure.
SUMMARY OF THE INVENTION
This invention is devices and techniques which use a negative pressure
(vacuum) applied through a surgical instrument, to fix the position of a
portion of the surface of a beating heart so that a surgical procedure can
be more easily performed. The devices disclosed herein apply a negative
pressure at several points on the outer surface of the heart such that a
portion of the exterior tissue of the heart is fixed in place by the
suction imposed through the surgical instrument. Because the negative
pressure introduced through the instrument fixes the position of a region
of tissue, the instrument remains at a constant distance from the
particular portion of the heart where the surgery is being performed. In
this configuration, the device may also serve as a support or platform so
that other surgical instruments or devices can be advantageously used at
the site. In certain preferred embodiments, the devices described herein
have structures to facilitate the use of additional surgical instruments
such that the placement of the negative pressure instrument permits the
surgeon to advantageously manipulate the other instruments used during the
surgery.
The negative pressure is preferably imposed through a plurality of ports
which may be disposed in a substantially planar surface of the instrument
which contacts the cardiac tissue. The ports are preferably oriented such
that the pressure is applied at several points over the target area to fix
the position of the tissue and to reduce any trauma to the tissue caused
by the negative pressure.
DESCRIPTION OF THE FIGURES
FIG. 1 is an embodiment of the invention having a substantially annular
housing with a plurality of suction ports disposed about the periphery of
the instrument and having openings in the bottom surface which contacts
the heart.
FIG. 2 is a dome-shaped or semi-spherical embodiment having a plurality of
suction ports disposed about the periphery of the bottom surface and
having several instrument ports in the dome portion through which
additional surgical instruments may be introduced, positioned, or
manipulated.
FIG. 3 is a section of a substantially circular embodiment showing a
preferred configuration for the suction ports and a pressure conducting
chamber for introducing the negative pressure to each suction port.
FIG. 4 is an embodiment of the instrument, in use, which is fixed on the
surface of the heart and has additional surgical instruments operably
associated therewith to facilitate a graft or a source artery being
attached to a target vessel form an anastomosis, for example, between the
internal mammary artery (IMA) and the left anterior descending (LAD)
artery.
FIG. 5 is an embodiment of the invention wherein the suction ports for
imposing the negative pressure are affixed to a shaft, which may be part
of a hand-held device, and are contained in a block where a plurality of
individual suction ports are arranged in an array.
FIG. 6 is a plurality of suction ports contained within a block having
vacuum lines attached thereto for introducing a negative pressure to each
suction port.
FIGS. 7 and 7a are sectional views of a block showing a configuration for
the suction ports and the pressure conducting space.
FIG. 8 is an array of suction ports having vacuum tubes which run the
length of the block and are oriented to be substantially perpendicular to
a passage space leading to each suction port.
FIGS. 9 and 9a are a hand held instrument, and a portion thereof, having a
removable block, wherein the instrument has a receiving means to
reversibly receive the block.
DETAILED DESCRIPTION OF THE INVENTION
This invention is surgical instruments and techniques which advantageously
apply a negative pressure to the surface of the heart so that a portion
thereof is maintained at a fixed position during a surgical procedure. The
negative pressure is introduced to the instrument and is applied at
several points over the surface of the heart proximate to or surrounding
the portion of the heart whose position is desired to be fixed during the
procedure. The instruments feature several suction ports which are brought
into contact with the heart, followed by the application of a negative
pressure through the instrument, to fix the position of a region of
cardiac tissue based on the placement of the instrument. The instruments
may also contain a sealed, airtight, pressure conducting chamber operably
connected to a pressure inlet for communicating the negative pressure to
the suction ports. Alternatively, each suction port may have a dedicated
vacuum line attached thereto.
The shape of the instrument may be varied depending on the particular
application or the clinical diagnosis for an individual patient. In some
embodiments, the shape of the instrument is defined by a housing forming a
complete or partial, substantially annular, ring-shaped housing having the
suction ports disposed about the periphery of the bottom surface of the
housing. The suction ports are contained within the base of the instrument
and the opening of the suction ports are contained in the bottom surface
of the instrument which may be substantially planar or may be shaped to
conform to the surface of the heart.
In another embodiment, the operative portion of the instrument may be
defined by one or more arrays of suction ports which are substantially
linear. The suction ports may be contained in a block which has at least
one vacuum line attached thereto. This design is particularly suitable for
an instrument having a shaft affixed thereto for positioning the block
containing the suction ports. The shaft may be fixed to a rigid support
during the procedure or may be part of a hand-held instrument having a
handle structure adapted to be grasped by the human hand. In a preferred
embodiment, the hand-held instrument contains a pair of shafts having a
block and suction port assembly at each end thereof. The shafts are
connected at an intermediate portion by a pivot which allows the suction
port assemblies to move relative to one another, to be oriented and
manipulated by hand, and to be locked into place in a desired
configuration.
An embodiment having more than one movable member in which suction ports
are contained offers the advantage that a negative pressure may be first
imposed through the suction ports of each movable member to fix the
tissue, followed by manipulation of the individual members which causes
the tissue to be stretched or oriented such that one portion of the
cardiac tissue is fixed in position by one movable member and can be
oriented relative to another portion fixed by a second movable member.
The negative or vacuum pressure imposed may be varied depending on the
design of the instrument, the orientation of the ports, and the amount of
pressure needed to hold a particular region of the heart in place. When
manipulating the instruments of this invention, it is not desired to exert
a downward force on the instrument once the instrument engages the cardiac
tissue because the tissue could be damaged by being drawn into the suction
ports, thus risking interruption of blood flow and ischemic or reperfusion
injury to the cardiac tissue. However, once a negative pressure is
imposed, the instrument may be drawn away from the heart such that the
portion of the surface tissue fixed by the suction ports is slightly
elevated relative to the remainder of the heart.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIGS. 1 and 3, an embodiment of the invention is an instrument
comprised of an annular housing 1 which could have an alternate shape
depending on the design and clinical application of the instrument. For
example, the body of the instrument has a housing which may be a portion
of a circle, an oval, semi-oval, U-shape, or linear member. The portion of
the housing 1 which contains the suction ports 2 has a bottom surface 6
which rests against the surface of the heart and therefore should be
substantially planar or curved to the extent necessary to simultaneously
bring the suction ports 2 into conforming contact with the heart.
Referring to FIGS. 1 and 3, one embodiment of the invention has suction
ports 2 equally spaced about the circumference of the annular housing 1.
For purposes of stability, it is preferred that each suction port 2 be
substantially equidistant from each adjacent port and their location
spread over the entire portion of the instrument at the points of contact
to the heart by the bottom portion of the instrument to more stably affix
the instrument to the surface of the heart when a negative pressure is
imposed. As described in detail below, the housing 1 may also have one or
more instrument ports 9 to facilitate introducing a surgical instrument to
the site of the surgery to function on or in proximity to the fixed
portion of the cardiac tissue.
The interior of the housing 1 may be further comprised of a means for
introducing a negative pressure to the suction ports 2. For example, each
suction port 2 may have a dedicated vacuum line 3 for introducing a
negative pressure to each suction port 2. However, it is preferred that a
single vacuum line 3 introduce the negative pressure via an inlet 5 which
leads to an airtight, sealed, and pressure conducting chamber 4 contained
within the annular housing 1 which in turn communicates the negative
pressure to each suction port 2. Thus, by connecting a negative pressure
source to the inlet 5, the negative pressure is introduced to the
instrument through inlet 5, thereby creating a negative pressure in the
pressure conducting chamber 4 which is communicated to each suction port
2. The housing may also have at least one instrument port 9 comprised of
an opening that preferably traverses the width of the housing and is
shaped to receive an instrument. In use, the surgeon may rely on the
housing 1 as a platform for other instruments which may advantageously be
used at the portion of the heart fixed in place by the negative pressure.
The instrument port 9 may be a simple opening in the housing I or may be
designed to operably receive a specific instrument as described in more
detail below.
In use (See FIG. 4), the instrument is gently positioned on the surface of
the heart by manipulating the position of the housing 1 such that the
suction ports 2 rest against the cardiac tissue. Once the instrument is
positioned on the surface of the heart, the negative pressure is applied
through vacuum line 3 and inlet 5 while the housing may be gently
manipulated to insure that the negative pressure is causing the cardiac
tissue to become fixed to the suction ports 2. Once the suction ports
become functionally attached to the surface of the heart, the portion of
the surface of the heart becomes fixed relative to the instrument. Once
the negative pressure is applied, the instrument may be attached to a
stable support such as a rib retractor or other structure which does not
move relative to the beating heart.
Referring to FIG. 2, a dome-shaped or semi-spherical embodiment of the
invention has a plurality of suction ports 2 spaced about the periphery of
the bottom surface 6 of the dome portion 8 such that the entire instrument
is fixed to the cardiac tissue at the point of contact by each of the
several suction ports 2. As with the above embodiment, it is preferred
that each suction port 2 be pneumatically connected via an air-tight
pressure conducting chamber 4. The base of the instrument is comprised of
a substantially flat bottom surface 6 wherein the opening of each of the
suction ports 2 is flush at the bottom surface 6. The bottom surface 6 is
preferably substantially flat because the bottom surface 6 will engage the
surface of the heart when the negative pressure is imposed. Alternatively,
depending on the size of the instrument and the location of placement on
the surface of the heart, the bottom surface 6 may be contoured so that
the suction ports 2 may engage a curved surface of the heart. The bottom
surface 6 may also have a separate contact layer 7 to cushion the contact
between the instrument and the heart tissue and to facilitate forming a
tight seal when the negative pressure is imposed. The contact layer 7 may
cover substantially the entire bottom surface 6 proximate to the openings
of the suction ports 2. If the contact layer material surrounds the
openings of the suction ports, it is preferable that the material not be
air permeable to prevent the negative pressure from passing through the
contact layer 7. Also, the contact layer 7 may be attached at the
periphery of the bottom surface 6. The available materials for the contact
layer 7 include the well-known and commercially available medical plastics
such as teflon, silicon, and others which are pliable and biocompatible.
The dome-shaped or semi-spherical embodiment of the invention preferably
has at least one instrument port 9 which may be placed in any of several
locations but which is preferably located in the dome portion 8 of the
apparatus. The instrument port 9 facilitates introducing the functional
portion of an instrument 10 into the interior of the dome portion 8, such
that the instrument 10 can perform any of several functions on or about
the cardiac tissue. The instrument 10 could include a cutting apparatus,
visual means, such as a scope or light, suturing instruments, suction,
blowing, or irrigation apparatus or any like instrument used during a
surgical procedure. Multiple instrument ports 9 disposed in the dome
portion 8 allow several instruments 10 to be introduced to the surgical
site from numerous directions and to be fixed in place relative to the
heart.
The instrument ports 9 may be comprised of only a simple opening in the
dome portion 8. Alternatively, the instrument ports 9 may also have a
flexible or rigid shaft 11 or other attachment means fixed to the dome
portion 8 to facilitate introducing an instrument or a member associated
therewith such as wires, tubes, cables, etc. which comprise or are used to
perform the function of the instrument 10. The shaft 11 may also comprise
the inlet (not shown) for introducing negative pressure to the pressure
conducting chamber 4. Because the dome portion 8 remains at a fixed
distance to the heart, the instrument ports 9 or shaft 11 may have a
collar 23 or stop associated therewith such that the distance between the
instrument 10 and the heart can be predetermined and fixed by, for
example, abutting a stop 12a on the instrument 10 against a stop 12b or
collar on the instrument port 9.
The instrument ports may also contain a locking means, which may be
magnetic or suction-driven, so that the instrument 10 can be locked into
place on the dome-portion 8. For example, the surgeon may view the
procedure via a scope 22 which communicates an image to a video monitor.
This invention may be advantageously used to establish and maintain an
optimal position for the scope by inserting the scope 22 through the
instrument port and then fixing the position of the scope 22. The end of
the scope 22 may have a collar 23 or other stop mechanism near its end,
such that the scope 22 may be introduced through the instrument port 9
wherein the movement of the scope 22 toward the heart is terminated by the
contact between the collar 23 of the scope 22 and the periphery of the
instrument port 9.
Referring to FIG. 3, a sectional view through line A--A of FIG. 1 shows the
interior of the pressure conducting chamber 4 and associated passages or
conduits associated with the suction ports 2 such that the negative
pressure in the pressure conducting chamber 4 is introduced from vacuum
line 3, via inlet 5, and ultimately to the suction ports 2 to provide the
means for introducing the negative pressure. The suction ports 2 have a
substantially circular opening 12 disposed in the bottom surface 6.
Although this embodiment has a single inlet 5 such that the pressure is
introduced to each suction portion 2 via the pressure conducting chamber
4, one or more of the suction ports 2 may each optionally have an
independent inlet 5' for a separate vacuum line 3'.
As noted above, the suction ports 2 are disposed within a bottom surface 6
which is preferably substantially flat. As noted above, the bottom surface
6 of the housing 1 may be a continuous ring or other annular shape which
contacts the heart about the entire periphery of housing 1, but may also
be comprised of a plurality of individual bases 13 which contain the one
or more suction ports 2 and which contact the heart at several independent
points which may be co-planar or which may be adapted to the contours of
the heart.
Referring to FIG. 4, FIG. 4 shows an embodiment of the invention in use in
a coronary artery bypass graft (CABG) procedure where an anastomosis is
formed between the internal mammary artery (IMA) 13 and the left anterior
descending artery (LAD) 14 which is held open by vessel retractors 16a and
16b. One end of the anastomosis is sewn to the LAD 14 by sutures 17 being
manipulated by instrument 10. A vacuum line 3 is attached to inlet 5, to
introduce a negative pressure to the pressure conducting chamber 4. An
instrument 10, which in this example is manipulating suture 17 for sewing
the anastomosis at the LAD 14, is introduced via instrument port 9a
located in the housing 1 of the apparatus. An instrument port 9a has a
shaft 18 disposed within the instrument port 9a to facilitate positioning
the instrument 10 relative to both the housing 1 and to the surgical site.
The shaft 18 traverses all or a portion of the instrument port 9a and may
be flexible such that the shaft 10 can be oriented in a fashion to direct
the instrument 10 to the desired point within the surgical field. The
shaft 18 may also be incorporated into a pivot 24 of any of several
configurations, including a ball 25 and socket 26 joint having a passage
27 running axially through the ball 25 wherein the shaft 18 is contained
in the passage 27 such that the ball 25 is rotated within the socket 26 to
rotate the instrument 10 about the pivot 24 to position the functional end
of the instrument 10. An example of another instrument 19 is inserted
through instrument port 9b by passing the instrument 19 through a rigid or
flexible shaft 12 which is disposed within the instrument port 9b. In this
example, the instrument 19 passes through the shaft 12 such that the
position of the functional end of the instrument 19 is fixed. In the
example shown in FIG. 4, the instrument 19 is being used to grasp the IMA
13 proximate to the attachment to the LAD.
Referring to FIG. 5, pursuant to this invention, the suction ports 2 may be
incorporated into a hand-held apparatus 20 having at least one shaft 21
attached to a suction port assembly 22 containing the suction ports 2, at
least one vacuum line 3, and a block 23 wherein the suction ports 2 are
contained. This embodiment is adapted for, may be manipulated by, a
surgeon or surgical assistant by hand grips 24 at the proximal ends of the
shaft or the hand grips 24 may be replaced by a conventional attachment
(not shown) for fixing the shaft 21 to a stable support such as a surgical
retractor or other such fixed structure available during the surgical
procedure. In a preferred embodiment, first and second shafts 21 are
interlinked by a pivot link 25 at an intermediate point in the shaft 21
such that each suction port assembly may be positioned independently of
one another either before or after the negative pressure is applied. In
this configuration, the cardiac tissue which is functionally attached to
the instrument at the points of contact with the suction port assembly 22
may be drawn apart by imposing a negative pressure through the suction
ports 2 and then independently manipulating the rigid shafts 21, or
proximally disposed hand grips 24 of the instrument 20 such that each
suction port assembly 22 is moved a distance from the other. The suction
port assembly 22 is comprised of the block 23, in which the suction ports
2 are contained, and a receiving means 29 located at the terminal (lower)
or distal end at the shaft 21 which is shaped to receive the block 23
which is in turn adapted to receive a vacuum line 3 to permit the
introduction of negative pressure from vacuum line 3 to the suction ports
2 contained within the block. The negative pressure is preferably imposed
by one or more vacuum lines 3 which may run parallel to the shaft 21
before terminating in the block 23 containing the suction ports 2 or at
any convenient point in the suction port assembly 22. In a preferred
embodiment, the blocks 23 are substantially rectangular structures wherein
the suction ports 2 are placed in an array as described below.
Referring to FIG. 6, the block 23 is comprised of a plurality of suction
ports 2 which are connected to vacuum line 3 to create a negative pressure
at each suction port 2. The number of individual vacuum lines 3 may be any
number less than or equal to the number of suction ports 2. An individual
suction port 2 may be connected to negative pressure via the pressure
conducting space 4 (See FIG. 7a) or by a passage 26 which communicates an
individual suction port 2 directly to the vacuum line 3. The passage 26 is
preferably smaller in circumference than the opening of the suction port
2. In the embodiment of FIG. 6, every suction port 2 is connected to a
vacuum line 3 which traverses substantially the length of the block 23.
Alternatively, every other suction port may also be connected to either of
two vacuum lines as shown in FIG. 8. In the embodiment of FIG. 8, the
passages 26 are oriented off-center to the circumference of the opening of
the suction port 2.
Referring to FIG. 7, a sectional view of the block 23 through line B--B of
FIG. 6 shows the suction ports 2 disposed within the block 23 in a linear
array such that each suction port is equidistant from each adjacent
suction port 2. The openings 12 of the suction ports 2 are flush with the
bottom surface 6 of the block 23. In this embodiment, a pair of vacuum
lines 3 connects each suction port 2 to negative pressure via a single
passage 26 which runs from the vacuum line 3 to the suction port 2 and is
substantially perpendicular to the vacuum line 3. Alternatively, as shown
in FIG. 8, vacuum lines 3 may connect each suction port 2 to negative
pressure.
Referring to FIG. 7a, the block 23 may also have an inlet 5 which
introduces the negative pressure to the suction ports 2. The suction ports
2 are disposed within the bottom surface 6 of the block 23 which is to be
affixed to the end of the shaft 21 (see FIGS. 5 and 9). As will be readily
appreciated, the negative pressure can be introduced to the suction ports
2 by a variety of techniques as described above. The vacuum line 3 may be
attached to the apparatus 20 at several points such as the individual
suction ports as illustrated in FIG. 7 or via a single inlet 5 and
communicated to each suction port 2 via pressure conducting space 4 (FIG.
7a) such that the negative pressure is introduced to the block 23 and
communicated to each suction port 2. Thus, the objective of communicating
the negative pressure to the suction ports 2 to fix the position of the
cardiac tissue may be achieved via several alternate techniques which are
based on or may be developed from the embodiments disclosed herein.
Referring to FIGS. 9 and 9a, as noted above the block 23 may be removable
from the apparatus 20. The terminal and distal end of the apparatus 20 has
a receiving means 29 which is adapted to reversibly receive the suction
port assembly and the block 23. In a preferred embodiment, the block 23 is
a separate molded rubber unit which is configured to fit reversibly into a
receiving means 29 at the terminal end of the shaft 21. In this
configuration, the suction port assembly 22 may be disassembled and the
block 23 disposed after a single use. The receiving means 29 is comprised
of a substantially parallel walls 27 having a grip means 28 associated
therewith to maintain the position of the block 23 in place when attached
to the receiving means 29. The grip means 28 may be one of several
alternate designs. For example, the block 23 may have a ridge or
indentation 30 which runs along the lateral exterior surface of the block
23 and fits conformingly in a groove or ridge 31 formed in the interior
face of the wall 27.
The particular examples set forth herein are instructional and should not
be interpreted as limitations on the applications to which those of
ordinary skill are able to apply this invention. Modifications and other
uses are available to those skilled in the art which are encompassed
within the spirit of the invention as defined by the scope of the
following claims.
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