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Description  |
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FIELD OF THE INVENTION
The present invention is directed to devices and methods for immobilization
of a localized region of a compliant body. The invention is suited for
immobilization of a localized region of a living organ without
significantly compromising normal physiological function. The devices and
methods are particularly suited for use in cardiovascular surgical
procedures.
BACKGROUND
In general, performing an exacting procedure on a compliant material can be
difficult due to the inherent evasive nature of the material. The
difficulty can be exacerbated if the compliant material is mobile. One
example of an exacting procedure performed on a mobile compliant material
is cardiovascular surgery performed on a beating heart. Devices and
methods are available for immobilizing the heart during cardiovascular
surgery. However, many available systems can have undesirable effects on
the patient.
Coronary artery bypass (CABG) surgery is a technique for revascularization
of the heart necessitated by coronary artery obstruction. Typically, this
procedure is facilitated by reducing or stopping the motion of the heart
to allow for accurate suturing of the anastamoses. Present methods for
reducing or stopping the motion of the heart include pharmacological and
presently available mechanical means. If the heart is stopped,
cardiopulmonary bypass (CPB) equipment (heart/lung machines) is used to
maintain systemic blood flow. The use of pharmacological agents, with or
without CPB equipment, and presently available mechanical methods to
restrain the heart have inherent disadvantages.
Pharmacological agents can be used to slow or stop the heart. Usually,
these drugs are administered systemically and in the case of cardioplegic
agents must have a short duration of action. One disadvantage of
pharmacological slowing of the heart is that the heart continues to beat
thus allowing only intermittent suturing of anastomoses between beats. In
addition, cardiac slowing compromises systemic circulation to vital organs
thus limiting broad application of these techniques without cardiac
support.
Generally, the use of cardioplegic agents necessitates use of
cardiopulmonary bypass (CPB) equipment or heart/lung machines. While
complete cardiac arrest allows accurate construction of anastomoses, CPB
equipment is expensive to operate and can cause significant
pathophysiological effects in the patient. Examples of pathophysiological
consequences which can occur with CPB equipment include cardiac
consequences, neurological consequences, pulmonary dysfunction, renal
dysfunction, hepatic dysfunction, coagulapathies, blood element trauma and
impairment of cell-mediated immunity.
Mechanical means to stabilize the heart during cardiac surgery use
compression or traction to sufficiently restrain the heart to permit
anastomoses of the vessels. Known mechanical devices are disclosed in, for
example, U.S. Pat. Nos. 3,983,863, 4,973,300 and 5,509,890. These devices
generally stabilize a localized area of the heart by compression. However,
compressive forces sufficient to stabilize the heart can functionally
deform the pumping chambers of the heart and impair cardiac filling or
effective pumping between cardiac contractions. Hence, cardiac output is
compromised. In addition, the frictional forces exerted by some devices
during restraint can cause tearing or abrasion of the epicardial surface
of the heart. Moreover, these devices have a limited range of access thus
limiting utility of such devices to situations where only one or at most
two adjacent arteries are to be bypassed.
Accordingly, there is a need for devices and methods to stabilize a
compliant body during performance of an exacting procedure. In the case of
living organs, there is a need to stabilize the organ without
significantly compromising normal physiological function and without
inducing trauma to the organ or the patient. Moreover, there is a need for
devices and methods to perform exacting procedures on living organs
without the use of costly patient support systems.
SUMMARY OF THE INVENTION
The present invention is directed to devices and methods to stabilize a
compliant body during performance of an exacting procedure. If the
compliant body is a living organ, the invention provides for stabilization
of the organ without significantly compromising normal physiological
function. The devices and methods disclosed herein advantageously provide
for the performance of some cardiovascular surgical procedures with a
reduced need for patient support systems.
The invention includes a unibody device for immobilizing a localized region
of a compliant body. As fully disclosed herein, a compliant body includes
an anatomical organ, such as a heart. According to the invention, the
unibody device includes, at least, a frame and at least two suction
arrangements coupled to the frame. The frame includes an elbow region
having an angle and a first and second arm which meet at, and extend from
the elbow region. At least one suction arrangement mounts to each arm of
the frame. The suction arrangement includes a pod for coupling the suction
arrangement to the frame, a releasable retainer mounted to the pod for
engaging the compliant material and an aspiration channel that passes
through the releasable retainer. The aspiration channel can communicate
with known aspiration sources.
In one embodiment, the frame includes an aspiration circuit that
communicates with the aspiration channel of the releasable retainer. An
aspiration circuit can be internal or external to the frame. The
aspiration circuit can be a "parallel" circuit by providing a vacuum
directly to each releasable retainer individually. Alternatively, the
aspiration circuit can be a "series" circuit by providing a vacuum to more
than one releasable retainer sequentially through an aspiration circuit.
The pod component of the suction arrangement can be removably coupled to
the frame. Alternatively, the pod can be integrated with the frame. The
releasable retainer can be removably coupled to the pod, or the releasable
retainer and pod can be integrated into a single piece.
The surface area of the region of a compliant body which can be immobilized
by the unibody device is adjustable. In one embodiment, the surface area
can be adjusted by extending the length of the arms. The arms of the
unibody device can be extended through use of a frame insert, a frame
telescope or addition of one or more extender pods. Alternatively, the
surface area to be immobilized can be altered by adjusting the size of the
angle between the arms. The angle can be adjusted, for example, by use of
a hinge or use of a malleable material at the elbow region. The use of a
malleable material at the elbow region allows for quick adjustment of the
elbow angle during surgery. In another embodiment, the entire device can
be prepared from a malleable material. This not only provides for
adjustment of the angle at the elbow region, but it also allows for "fine
tuning" the shape of the arms to follow the contours of the compliant body
being stabilized.
The unibody device can include a direct vacuum inlet or an indirect vacuum
inlet. A direct vacuum inlet provides a vacuum force from the source
directly to the aspirator channel of the releasable retainer. In contrast,
an indirect vacuum inlet provides a vacuum force from the source through
an aspiration circuit that communicates with the aspiration channel of the
releasable retainer.
The unibody device can also include a fixing arrangement. In one
embodiment, the fixing arrangement includes a handle for manual fixation
of the position of the unibody device. Alternatively, the fixing
arrangement can mount the unibody to a standard surgical retractor using a
fixing member that is malleable or has multiple articulations. The fixing
member can mount to the retractor using, for example, a retractor clamp
and one or more compression clamps.
In one embodiment, a unibody device of the invention is advantageous for
stabilizing a localized region of an anatomical organ, for example, a
heart during a surgical procedure. Cardiac surgical procedures which can
be performed using the unibody device include coronary artery bypass graft
(CABG) surgery, and tricuspid or mitral valve replacement or repair.
The devices and methods disclosed herein advantageously can be used to
perform cardiovascular surgery without incurring the financial or
pathophysiological costs of some patient support systems.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top plan view of a first embodiment of a unibody device
according to the invention.
FIG. 2 is a side plan view of the embodiment of the unibody device shown in
FIG. 1.
FIG. 3 is a cross-sectional view of a suction arrangement used with the
unibody device shown in FIGS. 1 and 2.
FIG. 4 is a top plan view of a second embodiment of a unibody device
according to the invention.
FIG. 5 is a side plan view of the embodiment of the unibody device shown in
FIG. 4.
FIG. 6 is a top plan view of a third embodiment of a unibody device
according to the invention.
FIG. 7 is a top plan view of a fourth embodiment of a unibody device
according to the invention. This embodiment includes pod extenders to
extend arm length.
FIG. 8 is a cross-sectional view of an arm extender and suction arrangement
used with the unibody device shown in FIG. 7.
FIG. 9 is an illustration of a unibody device positioned to immobilize a
region of the anterior epicardial surface of a heart around the left
anterior descending coronary artery.
FIG. 10 is an illustration of an embodiment of a unibody device including a
fixing arrangement.
DETAILED DESCRIPTION
It will be noted that in several places throughout the specification,
guidance is provided through lists of examples. In each instance, the
recited list serves only as a representative group. It is not meant,
however, that the list is exclusive.
The invention is directed to a unibody device and method for immobilizing a
localized region of a compliant material while the remainder of the
material remains relatively mobile. In one embodiment, a unibody device
can be used to immobilize a region of a beating heart surrounding a
coronary artery during coronary artery bypass graft surgery.
As used herein, the term "unibody device" refers to a device having a
single piece that is configured to flank (i.e., to place something on each
side of) a region of a compliant material substantially within the
perimeter of the shape of the single piece. As discussed below, in some
embodiments, the single piece can include a hinging arrangement or
telescoping arrangement to expand or contract the size of the region which
can be flanked. The unibody device also includes two or more arms which
are positioned relative to one another to provide immobilization of a
region of compliant material located between at least two of the arms.
Generally, the device is composed of a rigid material shaped to surround
the region to be immobilized. The device can completely surround the
region, however, typically it may not be necessary to completely surround
the region to provide adequate immobilization.
During use, the unibody device is positioned to flank the region of the
compliant material to be immobilized. Once positioned, a negative pressure
is exerted from the device to draw the compliant material snugly to the
device. It is believed that the combination of the negative pressure
drawing the compliant material to the device and the rigid perimeter
support of the device provides for the region within the perimeter of the
device to be immobilized while the region external to the perimeter of the
device remains relatively mobile.
In one embodiment, the unibody device is configured in a U-shape. According
to this embodiment, the area to be immobilized is positioned substantially
within the perimeter of the "U" and a negative pressure is applied to
engage the compliant material to the U. It is not necessary that the
entire perimeter surface of the device be able to exert a negative
pressure on the compliant material. Generally, the negative pressure is
applied at two or more locations along the arms of the U through, for
example, suction cups which provide contact between the compliant material
and the device. The amount of negative pressure applied need only be that
which is sufficient to adequately immobilize the region of the material
for the purpose immobilization is desired.
As used herein, the term "compliant material" or "compliant body" refers to
any material which tends to yield elastically or flexibly when a force is
applied to the material. According to the disclosure, a compliant material
includes non-living materials and living materials such as skin, fascia,
muscle, tendon, fat, etc. The term "compliant body" refers to a compliant
material having three dimensions and includes, for example, non-living
bodies and living bodies such as anatomical organs including, heart, lung,
kidney, liver, intestine, bladder, etc.
When referring to a unibody device of the invention, the term "rigid" is a
relative term. That is, in this context, a "rigid material" is a material
which is sufficiently "non-compliant" to provide adequate immobilization
of the particular compliant material on which the device is used. Hence, a
rigid material can also include, for example, a hardened rubber or a
malleable metal material that is flexible but has less flexibility than
the compliant material on which the device may be used. The term
"immobilization" is also a relative term. Generally, "immobilization"
refers to sufficiently restraining the mobility of a compliant material or
compliant body to permit an operator to adequately perform the procedure
for which immobilization is desired.
I. Unibody Device
A unibody device according to the disclosure includes, at least, a frame
and a suction arrangement. The device can also include one or more of an
arm extender, an aspiration circuit, a vacuum inlet, or a fixing
arrangement.
A. Frame
The "frame" of the unibody device includes an "elbow region" and at least a
first and second "arm" extending from the elbow region. The "elbow region"
is a region including an apex where the arms of the frame meet. The term
"arm" includes the non-apical portions of the elbow region referred to as
"branches," and any components mounted to the branches to extend the
length dimension of the device. That is, in some embodiments, the arms
include only the branches of the elbow region. In other embodiments, the
arms include herein described "arm extenders" which attach to the branches
or to other arm extenders to increase the length of the arm at its distal
end. The "apical end" of the arm is that end nearest the apex. The "distal
end" of the arm is that end farthest from the apex. The arms can be linear
or non-linear. As used herein, "non-linear" includes curved, S-shaped,
undulating, or other configuration which can provide flexibility in the
shape or size of the surface area immobilized by the device.
The elbow region can be an apical "arch", an apical "angle" or other apical
configuration. As used herein, an "arch" connotes a rounded elbow region
giving the device a "U-shaped" appearance when viewed from the top of the
device. An "angle" connotes a more acute intersection of the branches
giving the device a "V-shaped" appearance. The terms "arch" and "angle"
are used to aid in the visual description of the device, they are not to
be construed as limiting the shape of the apex of the elbow region.
Generally the angle of intersection of the arms of the frame at the elbow
region is about 0 degrees to about 160 degrees. In many embodiments the
angle of intersection will not exceed 90 degrees, and in some embodiments
will not exceed 60 degrees. When the frame is "U" shaped, the arms are
essentially parallel and the "angle" of intersection is a rounded arch.
The frame of the unibody device can be made from any material suitable for
the particular application of the device. For medical uses, the frame can
be prepared from solid or tubular materials including metals, metal-alloys
(nickel-titanium, stainless steel, etc.) and non-metals such as plastic,
plexiglass, ceramic, etc. The frame can be a malleable material which
advantageously provides for varying the shape of the arms of the frame to
more closely follow the contours of the compliant body.
The dimensions of the frame of a unibody device can vary. Generally, the
dimensions are limited only by the procedure in which the device will be
used. Typically, the size of the device used for a particular application
is determined by the surface area to be immobilized and by the space
available in the environment where the device is used. For medical
applications, the length of the unibody device from the apex to the distal
end of the arms can be about 4 cm to 15 cm, and the distance between the
arms, can be about 1 cm to 7 cm.
If the frame is a hollow tubular structure, the outside diameter of the
tubing can be about 2 mm to 11 mm. The inside diameter can be about 0.5 mm
to 9.5 mm. Preferably, the wall thickness of the tubing is at least 1.5
mm. In one presently preferred embodiment, the frame tubing has about a 4
mm inside diameter and about a 6 mm outside diameter. If the frame is a
solid structure, the cross-sectional dimension of a rectangular frame
structure can be about 2 mm to 12 mm by about 2 mm to 12 mm.
The surface area of a region of a compliant material which can be
immobilized can be fixed for a particular unibody device. Alternatively,
the surface area which can be immobilized can be adjustable. According to
the invention, there are at least three ways the size of the surface area
to be immobilized can be adjusted: (1) altering the size of the apex
angle; (2) altering the length of the arms; or (3) altering the shape of
the arms.
The size of the apex angle of a unibody device can be made adjustable by
including a hinging arrangement. A hinging arrangement includes a hinge
between the arms of the device at the elbow region. A hinging arrangement
can also include a locking device to maintain the arms in a fixed position
once the desired angle is selected. In an alternative embodiment, the
angle of intersection of the arms can be adjusted by use of a malleable
material which will not tend to crack or break upon repeated adjustment in
the elbow region. According to this embodiment, the angle of the apex can
be adjusted by pressing the arms together or pulling the arms apart to the
desired size. As previously stated, the entire frame can also be prepared
from a malleable material. Suitable malleable materials are known.
In yet another embodiment, the surface area between the arms can be
adjusted by telescoping one branch of the frame into a second branch in
the elbow region, at or near the apex. This embodiment is particularly
suited for a U-shaped frame. Additional arrangements for adjusting the
surface area immobilized by a unibody device are discussed below.
B. Suction Arrangement
In addition to a frame, a unibody device also includes a suction
arrangement. The suction arrangement includes a region of the device which
directly contacts the compliant material for engaging the compliant
material to the device. The suction arrangement can also include
components for increasing the surface area of the region immobilized by
extending the length of the arms.
The suction arrangement includes a "pod," and a "releasable retainer." The
releasable retainer includes a surface that directly contacts the
compliant material and an aspiration channel through which negative
pressure can flow to the contact surface of the releasable retainer. The
"aspiration channel" of the releasable retainer can connect directly to an
aspiration source or it can communicate with an aspiration source
indirectly through a hereinbelow described "aspiration circuit." As used
herein, the terms "negative pressure" and "aspiration" are synonymous and
refer to a vacuum force.
In general, the pod couples the suction arrangement to the unibody device,
typically on the arm of the frame. The pod also couples the releasable
retainer to the unibody device. The pod can be an integrated part of the
frame or it can be removably coupled to the arm. Alternatively, the pod
can be an integrated part of the releasable retainer, or the releasable
retainer can be removably mounted to the pod. As used here, the term
"integrated" means that the components are joined as a single piece. In an
embodiment of a pod that is not an integrated part of the arm, the pod can
be mounted to the arm using, for example, threads, latches, clamps,
clasps, rings, friction fit etc. If the pod is integrated with the frame,
the pod can be mounted to the frame by welding, brazing, soldering, poured
molding, etc.
The pod can be prepared from the same material as the frame. The pod can
also be prepared from the same material as the releasable retainer.
Alternatively, the pod can be prepared from a material different than the
frame or the releasable retainer. The size and shape of the pod can vary.
In some embodiments the pod can be configured and arranged to extend the
length of the arm when mounted to the frame. When used as an arm extender,
the pod may or may not include a continuation of the aspiration circuit to
communicate a negative pressure from an aspiration source to the
aspiration channel of the releasable retainer. The configuration and
arrangement of the pod can provide for the releasable retainer to be
mounted inside the perimeter of the frame, outside the perimeter of the
frame or directly in line with the frame. In addition, the pods can be
permanently fixed in relation to the frame or rotatably adjustable around
the long axis of the arm to conform the angle of the plane of the contact
surface with the contours of the surface of a compliant body.
The releasable retainer component of the suction arrangement includes a
"contact surface", the region of the device that directly contacts the
compliant material, or any covering or coating directly attached to the
compliant material, that is to be immobilized. Preferably, the composition
of the releasable retainer is selected from a material which is minimally
irritating to the compliant material. This is particularly desirable when
the compliant material is a living tissue. In one embodiment, a releasable
retainer can be a suction cup. Suitable minimally irritating or
nonirritating materials for a suction cup used with living tissues
include, for example, rubber, silicon rubber, latex, plastic, metal alloy,
etc. Known suction cups suitable for the invention are available.
The releasable retainer also includes an aspiration channel through which a
vacuum from an aspiration source can flow to the contact surface of the
releasable retainer. While it is conceivable that the unibody device could
perform its intended function without a vacuum, for most effective
functioning an aspiration channel for vacuum flow is preferred.
The releasable retainer can be removably mounted to the pod using known
methods, such as threads, latches, clasps, clamps, friction fit, rings,
etc. Alternatively, the releasable retainer and pod can be integrated.
The releasable retainer can be reusable. However, for hygienic purposes,
when used in a medical procedure, it is foreseen that the releasable
retainer will be disposed of after a single use. If the releasable
retainer and pod are integrated, the pod can also be disposable.
Generally, if the pod and releasable retainer are integrated, the
integrated components can be prepared from a material suitable for
directly contacting the compliant material, as discussed above for the
releasable retainer. A reusable releasable retainer for use in a medical
procedure is preferably prepared from a composition that can withstand
repeated sterilization.
During use, at least one releasable retainer should be present on each arm
of the unibody device. Typically, two or more releasable retainers are
present on each arm. However, the number of releasable retainers on each
arm does not have to be equal. The number of releasable retainers used for
a particular application can vary based on the particular compliant
material, the su | | |
