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FIELD OF THE INVENTION
The present invention relates generally to methods and devices for
performing cardiac procedures. More particularly, the present invention
relates to methods and devices of coronary revascularization without
placing the patient on cardiopulmonary bypass support.
BACKGROUND OF THE INVENTION
It is known that long-term relief from coronary artery disease and improved
longevity may be achieved through complete revascularization of a patient
who suffers from coronary artery stenosis or infarction of the myocardium.
Revascularization by coronary artery bypass grafting (CABG) has long been
the gold standard of total revascularization. In particular, a CABG
procedure in which the left internal mammary artery (LIMA) is anastomosed
to the left anterior descending (LAD) artery is well accepted as providing
a superior survival rate. However, conventional CABG procedures have many
drawbacks. Conventional CABG procedures require the patient to be placed
on cardiopulmonary bypass (CPB) support, and typically require either a
sternotomy or major thoracotomy to be employed. It is well known in the
medical community that CPB produces many deleterious effects to the
patient. A stemotomy is highly traumatic to the patient, requiring a
lengthy recovery period and having some risk of life-threatening
infection. As for a major thoracotomy, a patient typically endures much
postoperative pain from such a procedure. Additionally, the use of
Heparin, which is commonly prescribed for anticoagulation during a CABG
procedure, carries its own potential risks and complications which are
commonly known to surgeons. Furthermore, a CABG approach is often limited
where the subject artery or arteries have multiple segmental or diffuse
stenoses (e.g., the apex of the LAD), or where the arterial size is
unacceptable for grafting.
Consequentially, advanced catheter-based therapies, and percutaneous
transluminal coronary angioplasty (PTCA) in particular, have risen in
popularity in order to provide less invasive means for treating coronary
artery stenosis. These methods have the advantage of being less traumatic
and require a shorter recovery time. However, they are not without their
own limitations. It is known that PTCA carries a significantly higher
restenosis and reintervention rates than a CABG procedure for the left
anterior diagonal (LAD) artery, which provides the majority of blood flow
to the left ventricle which is responsible for cardiac output to the vital
organs. About 80-90% of patients suffering from symptomatic
atherosclerosis require revascularization of the LAD. Accordingly, the use
of catheter-based therapies alone to provide complete revascularization is
limited in many cases.
Under certain conditions, operative transluminal coronary angioplasty
(OTCA) has been used as an adjunct to CABG in the course of one operation.
Most commonly, OTCA has been performed through the arteriotomy used for
the grafting site, and then only in the context of standard CPB.
Unfortunately, OTCA has not shown a proven record of long-term patency
rates.
Considering all of the above, there is a need to for an improved method of
revascularization which optimizes the individual advantages of CABG
procedures and catheter-based interventions while eliminating some of the
drawbacks of these procedures when performed independently of the other.
Such a method would preferably involve a "hybrid" approach comprising a
CABG procedure performed in conjunction with catheter-based interventions
and/or diagnosis. The method would preferably eliminate some of the
drawbacks of conventional CABG procedures and, in particular, would
eliminate the need for CPB for the reasons discussed above. Applicant's
copending U.S. patent application, entitled "Method for Coronary Artery
Bypass" and having Ser. No. 08/419,991, discloses a method for performing
"Minimally Invasive Direct Coronary Artery Bypass Grafting" (MIDCAB.TM.)
on a beating heart, and is hereby incorporated by reference in its
entirety.
The MIDCAB method involves a direct access or "direct vision" approach in
which bypass grafting is accomplished through a small surgical "window" in
the patient's chest. This window is preferably a minimal thoracotomy
formed by an intercostal incision generally less than 12 cm. Access to the
heart is provided by a retractor which spreads the ribs both horizontally
and vertically. Other access ports through the thoracic cavity may be
employed if necessary but are not required. The MIDCAB method includes
techniques which eliminate the need for CPB while still providing a
substantially bloodless and stable operating field for ensuring a
successful anastomosis. Most advantageously, the portion of the heart
proximate to the vessel to be bypassed is stabilized, and a segment of the
vessel is occluded, preferably both proximally and distally to the
arteriotomy site. This is accomplished by providing ligating stay sutures
at the appropriate locations of the vessel or by other more sophisticated
stabilization means which are discussed in more detail below. The method
is primarily directed to grafting the LIMA to either the LAD, the diagonal
(Dx) and circumflex (Cx) arteries; the latter grafts being typically
accomplished by means of a "T-graft" with the radial artery from the LIMA
sequentially to the Dx and Cx arteries.
Furthermore, the MIDCAB approach is far less traumatic and less painful
than conventional approaches which require CPB and employ a stemotomy or a
major thoracotomy. Additionally, the MIDCAB method has been shown to
obviate the need for Heparin or require only minor doses.
SUMMARY OF THE INVENTION
The present invention generally involves methods for complete or partial
revascularization of a patient's coronary artery system which do not
require placing the patient on CPB. One aspect of the present invention
involves a hybrid approach to revascularization which employs a MIDCAB
procedure or other cardiac surgical procedure in combination with
catheter-based revascularization interventions. A MIDCAB procedure, for
example, may be employed when the LAD needs revascularization, and one or
more catheter-based procedures, such as PTCA for example, may be used to
revascularize other arteries which are not amenable to bypass grafting or
are otherwise unreachable by a MIDCAB procedure.
This hybrid approach is flexible, providing for either intraoperative
catheter procedures (i.e., where catheters are introduced "directly"
through a surgical opening in the patient's thoracic cavity) or
percutaneous catheter procedures (i.e., where catheters are introduced
through small incisions peripherally via, for example, a femoral artery).
For "direct" intraoperative catheterization, the present invention
provides improved methods and surgical instruments that allow
intraoperative catheter access to coronary arteries directly by means of
"central cannulation" of a coronary lumen such as the aorta or an artery
proximate to the aorta, such as the left subclavian artery, the left
common carotid artery, and the brachiocephalic trunk, commonly referred to
as the innominate artery.
The methods and devices of the present invention also enhance a physician's
ability to achieve complete coronary revascularization in the course of
one operation wherein the MIDCAB procedure is performed
"contemporaneously" with one or more catheter-based procedures, preferably
in one operating room and during a single application of anesthesia in
order to reduce the costs and to maximize the efficiency of the
revascularization process.
More specifically, in one embodiment of the present invention, a method of
revascularization is provided which includes performing at least one
minimally invasive coronary artery bypass graft procedure and
contemporaneously performing at least one catheter-based procedure in at
least one coronary artery while the heart is beating. The minimally
invasive coronary artery bypass graft procedure comprises stabilizing the
beating heart proximate to the coronary artery to be bypassed, with access
preferably provided via a minimal thoracotomy in the thoracic cavity. The
catheter-based procedure(s) may be either therapeutic or diagnostic or
both, and may involve delivering at least one catheter to a coronary
artery via a surgical or percutaneous opening in the thoracic cavity or
via a percutaneous opening at a location peripheral to the thoracic
cavity. The catheter-based procedure is performed contemporaneously with
the bypass graft procedure, and specifically prior to, during, or after
anesthetizing the patient for purposes of the bypass graft procedure.
Another embodiment of the invention involves a method of revascularization
performed on a patient without placing the patient on cardiopulmonary
bypass. The method includes forming at least one surgical opening in the
patient's thoracic cavity, and through a surgical opening, forming at
least one entry site in the wall of a coronary lumen. Preferably, the
coronary lumen is selected from the group consisting of the aorta, the
left subclavian artery, the left common carotid artery, and the innominate
artery. At least one elongated surgical instrument, such as a catheter, is
then introduced in the patient's coronary arterial system through the
entry site for treatment of the patient's coronary arterial system. The
entry site is formed by cannulating the coronary lumen. A particular
example of the procedure just described includes forming at least two
surgical openings in the patient's thoracic cavity wherein the subclavian
artery is cannulated through one of the two surgical openings.
Yet another aspect of the present invention involves accessing a patient's
coronary arterial system for the purpose of coronary revascularization, in
which heart contractions are not artificially halted, by first forming at
least one surgical opening in the patient's thoracic cavity, introducing
an arterial access device into the thoracic cavity via a surgical opening,
and then puncturing the wall of a coronary lumen with the arterial access
device. The arterial access device includes a cannula which is designed to
remain in the lumen wall upon puncturing. At least one elongated surgical
instrument can then be introduced into the patient's coronary arterial
system through the cannula to perform some interventional or diagnostic
function. This procedure further includes the step of sealing the lumen
wall at the puncture site around the cannula wherein the leakage of blood
at the puncture site is minimized.
The present invention also provides for a method of intraoperative
catheterization performed in conjunction with at least one minimally
invasive cardiac surgical procedure. This method involves creating at
least one minimally invasive opening in the patient's thoracic cavity
through which the cardiac surgical procedure is performed, forming an
entry site in the wall of a coronary lumen, introducing one or more
catheters through the one entry site, and advancing the distal end of a
catheters through the coronary lumen to a target site within a coronary
artery. Each of these steps is performed while the patient's heart is
beating. The coronary lumen through which the entry site is made depends
on the particular clinical diagnosis. The cardiac surgical procedure
performed may be, but is not limited to, a coronary artery bypass graft.
The present invention further provides for devices and a system of devices
for performing the methods described above. In particular, an arterial
access device is provided which includes a tubular member, such as a
cannula, having a proximal end and a distal end, and an elongated
puncturing member, such as a trocar, which is slideably disposed within
the tubular member. The puncturing member has a sharp distal end for
puncturing through the wall of a coronary lumen. The arterial access
device further includes a sealing member for engaging the coronary lumen
wall at the puncture site in order to minimize the leakage of blood from
the puncture site. The sealing member may be, for example, a tubular braid
or an expandable mechanism.
The present invention also provides for an intraoperative catheterization
system which includes an arterial access device for forming an entry site
in the wall of a coronary lumen via an opening in the patient's thoracic
cavity. The arterial access device comprises a cannula and at least one
flexible catheter which is adapted for direct insertion into the coronary
lumen via the cannula and which is positionable at the ostium of a
selected coronary artery to be revascularized. The cannula has a length
not substantially more than 30 cm. The catheter includes a tip portion
having a length not substantially more than 10 cm, a shaft portion having
a length not substantially more than 50 cm, and a profiled portion between
the tip and shaft portions. The profiled portion of the catheter is a bend
having an angle between about 20.degree. and 90.degree..
Preferably, at least one of the catheters of the intraoperative catheter
system is a guide catheter which has a tip design and a length adapted for
direct entry via central cannulation through the aorta, subclavian, or
other artery, and for facilitating the proper delivery of therapeutic and
diagnostic catheters or other surgical instruments to the ostia of the
coronary arteries selected for revascularization.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A is an isometric view of a device used to facilitate minimally
invasive access to the patient's cardiac area.
FIG. 1B is a perspective view of the device of FIG. 1A positioned in the
thoracic cavity of a patient for its intended application.
FIG. 2 is a schematic side view of one embodiment of the arterial access
device of the present invention.
FIGS. 3A-C are schematic representations depicting the operation of the
device of FIG. 2 upon insertion into a coronary lumen of a patient.
FIGS. 4A-C are schematic representations depicting the operation of another
embodiment of the arterial access device of the present invention upon
insertion into a coronary lumen of a patient.
FIG. 5 is a schematic illustration of the anterior view of a human heart
with one embodiment of the arterial access device and intraoperative
catheters of the present invention positioned in the aorta.
FIG. 6 is a schematic illustration of an embodiment of a guide catheter of
the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The methods of the present invention are suitable for performing complete
or partial revascularization of a patient's coronary artery system where
the patient is not placed on CPB; hence, the revascularization
procedure(s) are intended to be performed while the patient's heart is
beating. The revascularization method(s) involves, at least in part, one
or more catheter-based treatments performed contemporaneously with one or
more cardiac surgical procedures. Such catheter-based therapies include
but are not limited to angioplasty, perfusion, stent placement,
extraction, ablation, and drug delivery. Several cardiac surgical
procedures are suitable in the context of the present invention including,
but not limited to, CABG, electrophysiology procedures, myocardial
ablation therapy, congenital heart repairs, and valvuloplasty. Preferably,
such contemporaneously performed cardiac surgical procedure is a MIDCAB
procedure.
By "contemporaneously," it is contemplated that all revascularization
procedures be performed in spacial and/or temporal proximity to each
other, and preferably in one room (i.e., the operating room) during the
course of a single anesthetization of the patient. Also, the procedures
may be performed sequentially or simultaneously.
All catheter and surgical procedures are performed through one or more
minimally invasive surgical openings. Preferably, only one minimally
invasive surgical opening is made if the procedure(s) are done under
direct vision through the patient's thoracic cavity; however, more
openings may be necessary if catheters are peripherally introduced via the
femoral arteries and/or a thoracoscope is used. With respect to the
catheter-based procedures, the present invention provides for the
introduction of catheters either directly through the thoracic cavity or
peripherally through other percutaneous openings.
Procedures involving peripherally (often referred to as "percutaneously")
inserted catheters, such as with PTCA, provide for the insertion of one or
more catheters via a percutaneous penetration at a location peripheral to
the diseased coronary artery. Most commonly, a catheter is introduced into
one of the patient's femoral arteries at the patient's groin, and then
directed to the target site in a selected coronary artery. The arterial
length to be traversed in such a procedure involves a risk of dissection
of the arterial lining, (e.g., either in the stenotic plaque or the
arterial intima). This dissection allows blood flow between the arterial
wall and the dissected lining which may constrict the flow passage or
cause a section of the dissected lining, commonly called a "flap," to be
forced into the flow passageway thereby partially or completely blocking
the blood flow through the artery. This risk may be minimized if the
coronary artery to be treated is accessed directly through the thoracic
cavity, rather than accessed peripherally.
On the other hand, intraoperative catheterization by means of cannulation
of a coronary lumen under direct vision, or central cannulation as it is
commonly referred, has its own risks. Of particular concern is the risk of
stroke to the patient caused by plaque which may be broken loose from the
endothelial lining of the coronary lumen upon cannulation of the coronary
lumen.
Thus, while both percutaneous and intraoperative catheter techniques have
their respective advantages and associated risks, the flexibility of the
present invention allows a physician to employ the technique which is most
advantageous for the patient based on the particular clinical diagnosis.
The various methods of the present invention for performing
revascularization of a patient's coronary artery system will now be
described in more detail. A MIDCAB procedure is used herein as an example
of a contemporaneous cardiac surgical procedure which is performable in
the context of the methods of the present invention, however, it is
readily appreciated that the techniques and instruments discussed herein
may be applied to other procedures (examples mentioned above) depending on
the clinical diagnosis. In addition, the MIDCAB procedure is described
herein as being performed through a minimal left thoracotomy, however, it
is also readily appreciated that the procedure may be accomplished by
means of a minimal right throracotomy, a minimal sternotomy, or smaller
percutaneous openings in the thoracic cavity and by use of a thoracoscope.
For purposes of describing intraoperative catheterization methods of the
present invention, exemplary treatments and particular types of catheters
are discussed. The description following is not intended to limit the
present invention to these specific procedures, treatments, and
instruments, but is intended to be only exemplary of the present
invention.
In addition, a particular order of revascularization procedures has been
chosen for purposes of discussion, however, this order is not intended to
be limiting to the present invention. In fact, the order in which the
revascularization procedures are performed is patient-specific and depends
on the clinical diagnosis in each case. For example, a particular
diagnosis might require that a MIDCAB or other cardiac surgical procedure
be performed first followed by one or more catheter-based therapies.
Starting with a MIDCAB procedure which successfully establishes critical
blood flow through the LAD, for example, is advantageous where it is then
determined that the need for interventional catheter methods is obviate.
On the other hand, the diagnosis might require the physician to first
perform a PTCA procedure, for example, on a selected coronary artery,
either before or after the patient is anesthetized. The success of the
PTCA procedure may then be assessed by use of one or more diagnostic
catheter methods. Upon completion of catheterization procedures, one or
more bypass grafts may then be employed on the same or other coronary
arteries.
In another case, a MIDCAB procedure may be performed simultaneously with a
catheter-based procedure, wherein the catheters are inserted
intraoperatively, percutaneously, or both intraoperatively and
percutaneously. Notwithstanding a particular clinical diagnosis and a
particular order of procedures, under the method of the present invention,
all revascularization procedures are performed contemporaneously within a
single period of time for which the patient may be completely
anesthetized, and preferably in one operating room, on one operating
table, and by one physician.
Turning now to a detailed description of the surgical process, the patient
undergoing the procedure is prepared for cardiac surgery, and is placed
under general anesthesia. Once anesthetized, the patient may be intubated
with a double-lumen endobronchial tube, for example, which allows for the
selective ventilation or deflation of the right and left lungs. As all
procedures of the present invention are performed on a beating heart, no
steps are taken to place the patient on CPB and administer cardioplegia
solution as would otherwise be done at this point in a conventional
operation.
After the patient has been prepared as described above, the physician
commences the revascularization surgery by making one or more percutaneous
surgical openings. The number of percutaneous openings and the optimal
location of each opening will depend on several factors: (1) the location
of the arteries to be revascularized by means of a MIDCAB procedure, if
any; (2) the location of the arteries to be revascularized by means of
catheter-based procedures; and (3) the anatomy and physiology of the
particular patient.
At least one surgical opening will be formed in the thoracic cavity to
allow for the introduction of surgical instruments for the designated
surgical procedure for revascularizing at least one coronary artery or
repairing or reconstructing a valve, for example. Preferably, only one
surgical opening is made within the thoracic cavity of the patient.
However, a thoracoscope may be employed, requiring multiple surgical
openings in the patient's thoracic cavity. Additionally, one or more
peripheral percutaneous openings (e.g., in the patient's groin) may be
employed if necessary for a particular catheter-based method.
If a MIDCAB procedure is performed, a single minimal thoracotomy is
preferable as it provides a surgical window sufficient to accommodate
surgical instruments for the MIDCAB as well as catheters and other
instruments (i.e., cannula, trocar, guide wire, probes, etc.) for carrying
out revascularization. Minimally invasive openings (i.e., those having an
incision length not substantially more than 12 cm, preferably less than 12
cm, and most preferably less than 10 cm) are preferable; however, larger
incisions may be employed if necessary. As between a minimal thoracotomy
and multiple port-like percutaneous openings which require the physician
to perform the surgery with a thoracoscope and possibly a separate light
source, a minimal thoracotomy is preferable because of the greater
visibility and accessibility provided by it. The minimal thoracotomy
incision may be intercostal or parasternal but is preferably performed
intercostally, and preferably on the second, third, fourth, or fifth
intercostal spaces, and most preferably on the fourth or fifth intercostal
spaces. If employed, multiple percutaneous ports may be formed on either
the left or right side of the patient's thoracic cavity, however, the
exact locations are dependent upon the above enumerated factors. The means
for creating these ports are commonly known in the art of cardiac surgery.
In the case where a minimal thoracotomy is used, and particularly when one
or more bypass grafts are contemplated, the surgery is preferably
performed in part by means of the Minimally Invasive Direct Coronary
Artery Bypass (MIDCAB.TM.) method and system as described in Applicant's
copending patent applications having Ser. No. 08/419,991, mentioned above,
and Ser. Nos. 08/603,758, 08/604,161, and 08/619,903 which are hereby
incorporated by reference in their entirety. The MIDCAB system is
comprised of surgical instruments designed to provide atraumatic
attenuation of heart motion during cardiothoracic surgery and, therefore,
is ideal for cardiothoracic surgeries when the patient is not on CPB. More
specifically, the MIDCAB system is used to spread the ribs, providing
access to the thoracic cavity, retract the skin from the surgical
incision, dampen the movement of the beating heart, and isolate and
present the target cardiac vasculature.
A MIDCAB device 30 is illustrated in FIGS. 1A and 1B with FIG. 1B showing
the device within a patient's thoracic cavity functioning in its intended
application. In general, MIDCAB device 30 includes access platform 32 and
stabilizer 48. Access platform 32 in turn includes a spreader 34 having a
housing and a spreader knob 35. Extending from spreader 34 is a stationary
retractor arm 36 and a moveable retractor arm 38. Enclosed in the housing
of spreader 34 is a cable drive mechanism (not shown) which is operated by
rotating spreader knob 35, which can accommodate about 50 lbs/in.sup.2 or
more of torque. This cable drive mechanism laterally translates retractor
arm 38 away from retractor arm 36. The operation of spreader knob 35 with
spreader 34 may alternatively comprise other suitable configurations such
as a rack and pinion mechanism.
Retractor arms 36 and 38 each have two joints 33 having an axial rotation
of about 40.degree. for optimal adjustment of arms 36 and 38 when in
operation. Attached to the distal ends of retractor arms 36 and 38 are
retractor blades 40 and 42, respectively. Blades 40 and 42 are designed to
be positioned within an incised intercostal space and have recessed
throats 41 and 43 to engage with the rib adjacent thereto. Extending from
blades 40 and 42 are a set of skin retractor fingers 44 and 46,
respectively.
Stabilizer 48 comprises a stabilizer arm 50 which is slideably mountable to
either retractor arm 36 or 38. At the distal end of stabilizer arm 50 is a
stabilizer shaft 52 which is in omnidirectional communication with
stabilizer arm 50 by means of a ball and socket mechanism 54. Stabilizer
arm 50 is adjustably fixed 61 to a retractor arm by stabilizer knob or
wing nut 60 and clamp 61. Such a configuration allows liberal positioning
of stabilizer shaft 52 within the planar area between retractor arms 36
and 38. The distal end of stabilizer shaft 52 has a stabilizer foot 56
having tines 58 which have a surface designed to atraumatically grip the
epicardium of the heart.
MIDCAB device 30 may also include other optional accessories (not shown)
which are mountable or attachable to either access platform 34 or
stabilizer 48. Such accessories include but are not limited to a scope, a
light, an arterial graft holder, and a suture holder.
MIDCAB device 30 is employed as follows: in an initially collapsed state,
the device 30 is placed over the incision with retractor arms 36 and 38
positioned intercostally between opposing ribs which are proximal to the
chest incision. After retractor blades 40 and 42 are engaged with the
ribs, skin retractor fingers 44 and 46 are to be bent away from each other
over the patient's skin to displace soft tissue away from the incision.
Spreader knob 35 can then be rotated to displace moveable retractor arm 38
in a lateral direction away from stationary retractor arm 36 causing the
ribs to spread laterally and displace vertically with respect to each
other.
Once the desired opening size is achieved, the physician can proceed with
the revascularization procedures. With respect to a MIDCAB procedure,
after access has been established, an arterial blood source is then
prepared for subsequent bypass connection to the narrowed coronary artery
to be bypassed at a location beyond the narrowing. The arterial blood
source may be supplied by either an existing artery, such as the left
internal mammary artery (LAMA), or by shunting a natural or synthetic
blood vessel, typically a length of the saphenous vein, from the aorta to
the target vessel. However, it is preferable to use a peticled or
transected arterial conduit, such as the LIMA, the right anterior
descending artery (RIMA), or the gastroepiploic artery as they tend to
have a better patency rate and require only one anastomosis. When an
existing artery is used as the graft vessel, it is preferably harvested
from its natural location by means identified in the above-identified
patent applications which have been incorporated by reference.
After the graft vessel is harvested and prepared for the anastomosis, the
target site of the coronary artery to be bypassed is identified. Most
typically, the diseased coronary artery which is the subject of the bypass
is the LAD, however, the methods of the present invention are suitable for
bypassing other arteries including the right coronary artery (RCA), the
obtuse marginal artery, the ramus intermedius artery, and the posterior
descending artery, among others.
Stabilizer arm 50 with the attached stabilizer shaft 52 is then connected
to either retractor arm 36 or 38 depending on the physician's preference.
Stabilizer shaft 52 is then positioned above the target coronary artery to
be bypassed and carefully lowered to the epicardium. Incremental pressure
is applied to the epicardium until the desired stabilization of the heart
is achieved, i.e., until the contraction of the heart does not cause
either vertical or horizontal motion at the target site. Stabilizer shaft
52 is then locked into place by turning stabilizer knob 60. Optimal
stabilization of the epicardium is achieved when the vessel between tines
58 of stabilizer foot 56 is stable relative to the heart's motion. At this
point, the anastomosis is performed between the graft vessel and the
target vessel by various means commonly known in the art of cardiac
surgery. FIG. 1B is a perspective view of the MIDCAB device of FIG. 1A in
application in a patient's thoracic cavity 66. Here, a physician is shown
performing the anastomosis with surgical instruments 62 and 64 while
movement of the patient's heart is being stabilized by stabilizer foot 56.
Catheterization may now be performed either directly through the minimal
thoracotomy, or through peripheral percutaneous openings, or both. For
purposes of this description, intraoperative catheterization is described
as being performed through the minimal thoracotomy wherein catheters are
directly inserted into the coronary artery system via a cannula which is
to be introduced into the wall of the patient's aorta. However,
percutaneous insertions sites (e.g., the groin area) and other coronary
lumen entry sites (e.g., the femoral artery, subclavian artery, left
subdlavian artery, etc.) are contemplated. For example, based on the
clinical diagnosis, it may be determined that cannulation of the
subclavian artery is preferential to cannulation of the aorta. As the
subdlavian artery may be more difficult to access (for purposes of
cannulation) than the aorta from a minimal thoracotomy in the fourth or
fifth intercostal space, a percutaneous opening through the chest wall
directly above the subdlavian artery and superior to the minimal
thoracotomy opening may be required for cannulation of the subdlavian
artery.
Prior to commencing intraoperative catheterization (in the context of the
minimal thoracotomy described above, with or without a MIDCAB procedure),
it may be necessary to optimize visualization of and access to the aorta.
This necessity may arise when access is made at a location in the thoracic
cavity which is below the fourth intercostal space. This may involve
readjusting the access platform component 32 or utilizing another
retractor or rib pry-bar (as disclosed in Applicant's patent applications
having Ser. Nos. 08/604,161 and 08/619,903) to further offset the rib
cage. After having established adequate access to and visibility of the
aorta (whether through a minimal thoracotomy or through one or more
percutaneous ports), the physician is ready to cannulate the aorta.
Cannulation of the aorta or other appropriate coronary lumen is
accomplished with the present invention by means of an arterial access
device 100 of FIG. 2. Access device 100 has a tubular body or cannula 102
having a top portion 104 and a shaft portion 106 and housing a central
lumen. Cannula 102 is preferably relatively small in size and may be rigid
or flexible. Cannula 102 may be made of a metal, plastic, polyurethane,
polyethylene, polycarbonate, nylon or other similar materials suitable for
medical applications. Extending upwardly at an angle from top portion 104
are two auxiliary tubular arms or ports 112 and 113 each having a central
lumen which is in fluid communication with the central lumen of cannula
102. Although two arms are shown, none are required and any number of arms
are contemplated within the scope of the present invention. The purpose
and function of such auxiliary arm(s) is discussed in more detail below
with respect to FIG. 5. At the proximal end 108 of cannula 102 is a valve
mechanism 110 which prevents blood from flowing out of end 108 and allows
insertion of a trocar or catheter without leakage. Valve mechanism 110 is
preferably a rotating hemostatic valve or Luer fitting which selectively
seals or provides access to the central lumen. Such valves or fittings are
commonly used in the art of cannulation and catheterization. Other valve
mechanisms which are suitable for such an application may also be used
with the present invention. When closed, valve mechanism 110 seals port
122 closed. Also illustrated but optional, are valve mechanisms 124 and
125 at the opening of arms 112 and 113, respectively. Valve mechanisms 124
and 125 function similarly to valve mechanism 110. The distal end of
cannula 102 comprises an atraumatic tip 114 which is made of a compliant
plastic or other similar material. Tip 114 preferably has a smooth shape
so as not to damage the tissue upon entering the aortic wall. Also, tip
114 is preferably radially expandable upon entering the aortic wall or has
a width which is slightly greater than that of shaft 106 so as to anchor
cannula 102 within the aortic wall.
Positioned concentrically within cannula 102 is a trocar or introducer
device 118 (partially shown in phantom) having a tapered body which ends
distally in a very sharp point 119 (shown in phantom) and having a head
120 at the proximal end. Head 120 has a dimension such that it sealingly
engages with port 122. Trocar 118 is relatively rigid and may be made of
materials (listed above) similar to those used for cannula 102. Cannula
102 has a length not substantially greater than about 30 cm, and trocar
118 has a length such that it extends beyond the end of atraumatic tip
114. The specific length of cannula 102 and trocar 118 are dependent upon
the coronary lumen being cannulated. Cannula 102 has an internal diameter
of not substantially more than 5 French and preferably less than 5 French,
and trocar 118 has an external diameter such that it is slideably moveable
within cannula 102. It is preferable that the arterial access device of
the present invention, and particularly the diameters of cannula 102 and
trocar 118, have relatively small profiles to ensure a small puncture site
in order to reduce trauma to the coronary lumen and to minimize the
possibility of extricating plaque that has formed on the interior of the
lumen.
Positioned concentrically around the distal end of cannula 102 is a sealing
member 116 and a sleeve 115. Sealing member 116 may be an expandable
sheath, such as a coated metal braid, an inflatable balloon, or other
similar means, which sealingly engages with an arterial wall when operably
positioned therein (see FIGS. 3A-C). Sealing member 116 is shown as
expandable braid having its distal end connected to the tip of cannula
102. Extending from the proximal end of sleeve 115 is elongated arm 117
which runs approximately parallel cannula 102. In the case of a balloon
type sealing member, actuating lever is in the form of a syringe for
inflation and deflation of the balloon. A clip 123 serves to maintain
elongated arm 117 in a parallel relationship with cannula 102. Mounted at
the proximal end of elongated arm 117 is head 121. Actuating member 115 is
slideably moveable along the length of cannula 130 to actuate expansion of
braid 132. Alternatively, sealing member 116 may comprise a flexible
flange or other similar mechanism which is flexible enough to
atraumatically enter the entry site and then automatically radially expand
upon entry into a coronary lumen without the need for an actuating means.
FIGS. 3A-C illustrate the operation of the sealing member of the arterial
access device of FIG. 2 upon insertion into a coronary lumen, such as the
aorta. Cross-sectional views are provided of the distal portion of a
cannula 130, a trocar 134, braid 132 having a constricted portion 133, and
sleeve 131 of an arterial access device of the present invention. FIG. 3A
illustrates trocar 134 puncturing lumen wall 140 in the direction of arrow
142. Cannula 130 is introduced into lumen wall 140 with atraumatic tip 136
snugly passing through the puncture site and until constricted portion 133
of braid 132 reaches the edges of lumen wall 140 (FIG. 3B). Sleeve 131 is
then pushed downward, in the direction of arrow 144, compressing braid 132
and causing braid 132 to expand radially as the ends thereof are axially
moved closer together wherein the portions of braid 132 above and below
artery wall 140 are caused to expand radially outward to seal the entry
site (FIG. 3C). Trocar 134 can then be removed from cannula 130 in the
direction of arrow 146. Although braid 132 is illustrated as having
expanded portions above and below artery wall 140, other embodiments which
provide expansion either above or below artery wall 140 are contemplated.
FIGS. 4A-C illustrate similar cross-sectional views of the operational
steps involved in the insertion of another embodiment of the arterial
access device of the present invention having a cannula 170, a trocar 174,
a braid 172, and a sleeve 171. Sleeve 171 is provided with a stop member
173 which is extends radially from the distal end of sleeve membe | | |
