 |
Description  |
|
|
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
heart. For many years, surgeons have performed "open-heart" surgery to
repair defects in 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 contribution 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 preventing 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 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 being inserted to form an
anastomosis between the internal mammary artery (IMA) and the left
anterior descending (LAD) artery.
FIG. 5 is an alternative 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
attached thereto a pair of vacuum lines for introducing a negative
pressure to each suction port.
FIGS. 7 and 7A are sectional views of the block showing an alternate
configuration for the suction ports and the pressure conducting space.
FIG. 8 is an alternative embodiment for 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 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 the tissue based
on the placement of the instrument. The instruments may also contain a
sealed, airtight, pressure conducting chamber for operably connected to a
pressure inlet for communicating the negative pressure to the suction
parts. 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 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.
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 housing 1. For
purposes of stability, it is preferred that each suction port 2 be
substantially equidistant from each adjacent port and spread over the
entire portion of the instrument at the points of contact to the heart so
that the instrument is more stably affixed 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 advantageously
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 1 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 each
suction port 2 rests 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 each suction port 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 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 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
advantageously 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 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 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 at 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. 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 have an
independent inlet 5.sup.1 for a separate vacuum line 3.sup.1.
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 and 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 of the graft.
Referring to FIG. 5, pursuant to this invention, the suction ports 2 may be
incorporated into a hand-held apparatus 20 having a shaft 21 attached to a
suction part 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 may be operated by a surgeon or surgical assistant by hand
grips 24 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, a pair of 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 manipulating the rigid shafts 21, or 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) end at the shaft 21 which is shaped to
receive the block 23 and to permit introduction of the 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 suctions 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 parts 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 other suction port 2 is connected to
either of two vacuum lines 3 which traverse substantially the length of
the block 23. Alternatively, each suction port may also be connected to a
single suction line as shown in FIG. 8. In the embodiment of FIG. 6, the
passages 26 are oriented off-center to the circumference of the opening of
the suction port 2. 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.
Referring to FIG. 7, a sectional view of the block 23 through line B--B of
FIG. 6 shows the suction ports 2 disposed with 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, a single vacuum line 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 FIG. 5). 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 end of the apparatus 20 has a
receiving means 29 which is adapted to reversibly receive the block 23. In
a preferred embodiment, 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.
* * * * *
|
|
 |
|
 |
Description |
|
