U.S. patent application number 10/745844 was filed with the patent office on 2004-07-15 for method and system for selective or isolated integrate cerebral perfusion and cooling.
Invention is credited to Barbut, Denise R., Patterson, Russel H..
Application Number | 20040138608 10/745844 |
Document ID | / |
Family ID | 46257822 |
Filed Date | 2004-07-15 |
United States Patent
Application |
20040138608 |
Kind Code |
A1 |
Barbut, Denise R. ; et
al. |
July 15, 2004 |
Method and system for selective or isolated integrate cerebral
perfusion and cooling
Abstract
Patients having diminished circulation in the cerebral
vasculature as a result of cardiac arrest or from other causes are
treated by flowing an oxygenated medium through an arterial access
site into the cerebral vasculature and collecting the medium
through an access site in the venous site of the cerebral
vasculature. In addition to oxygenation, the recirculating blood
may also be cooled to hypothermically treat and preserve brain
tissue. Isolation and cooling of cerebral vasculature in patients
undergoing aortic and other procedures is achieved by internally
occluding at least the right common carotid artery above the aortic
arch. Blood or other oxygenated medium is perfused through the
occluded common carotid artery(ies) and into the arterial cerebral
vasculature. Usually, oxygen depleted blood or other medium leaving
the cerebral vasculature is collected, oxygenated, and cooled in an
extracorporeal circuit so that it may be returned to the
patient.
Inventors: |
Barbut, Denise R.; (New
York, NY) ; Patterson, Russel H.; (New York,
NY) |
Correspondence
Address: |
O'MELVENY & MEYERS
114 PACIFICA, SUITE 100
IRVINE
CA
92618
US
|
Family ID: |
46257822 |
Appl. No.: |
10/745844 |
Filed: |
December 23, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10745844 |
Dec 23, 2003 |
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09904016 |
Jul 11, 2001 |
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6736790 |
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09904016 |
Jul 11, 2001 |
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09256965 |
Feb 24, 1999 |
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60076222 |
Feb 25, 1998 |
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60096218 |
Aug 12, 1998 |
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Current U.S.
Class: |
604/6.13 ;
604/4.01; 604/6.14 |
Current CPC
Class: |
A61M 1/3613 20140204;
A61M 1/3621 20130101; A61M 1/3603 20140204 |
Class at
Publication: |
604/006.13 ;
604/006.14; 604/004.01 |
International
Class: |
A61M 037/00 |
Claims
What is claimed is:
1. A method for cerebral cooling, comprising the steps of:
inserting a first catheter into a right common carotid artery and
expanding an occlusion member disposed about the first catheter;
inserting a second catheter into a left common carotid artery and
expanding an occlusion member disposed about the second catheter;
inserting a third catheter into an inferior vena cava and expanding
an occlusion member disposed about the third catheter; flowing
oxygenated medium from the first catheter into the right common
carotid artery; flowing oxygenated medium from the second catheter
into the left common carotid artery; and withdrawing medium from
the inferior vena cava.
2. The method of claim 1, further comprising the step of stopping
blood flow within the aorta.
3. The method of claim 1, further comprising the step of performing
a diagnostic or interventional procedure on the aorta.
4. The method of claim 1, further comprising the step of performing
an open surgical interventional procedure on the aorta.
5. The method of claim 1, further comprising the step of performing
repair of an aortic aneurysm, repair of an aortic dissection,
reconstruction of the aorta, or endarterectomy.
6. The method of claim 1, further comprising the step of inserting
a fourth catheter into a descending aorta and expanding an
occlusion member disposed about the fourth catheter.
Description
[0001] This is a continuation of Barbut et al., U.S. application
Ser. No. 09/904,016, filed Jul. 11, 2001, which is a continuation
of Barbut et al., Ser. No. 09/256,965, filed Feb. 24, 1999, which
is a continuation-in-part of Barbut et al., U.S. Application Serial
No. 60/076,222, filed Feb. 25, 1998, entitled "Method and System
for Emergency Cerebral Perfusion," and a continuation-in-part of
U.S. Application Serial No. 60/096,218, filed Aug. 12, 1998,
entitled "Methods and Apparatus for Isolation of the Cerebral
Vasculature." All of the above-identified applications are
expressly incorporated herein by reference in their entirety.
FIELD OF THE INVENTION
[0002] The present invention relates generally to medical devices
and methods. More particularly, the present invention relates
generally to methods, systems, and kits for perfusing and
optionally cooling the cerebral vasculature of a patient with
oxygenated blood or other media.
[0003] Cerebral ischemia, i.e., reduction or cessation of blood
flow to the cerebral tissue, can be characterized as either focal
or global. Focal cerebral ischemia refers to reduced perfusion to
the cerebral tissue resulting from a partial or complete occlusion
in the intracranial or extracranial cerebral arteries, e.g.,
stroke, subarachnoid hemorrhage spasms, iatrogenic vasospasm.
Global cerebral ischemia refers to reduced perfusion to the
cerebral tissue resulting from systemic circulatory failure caused
by, e.g., cardiac arrest, shock, circulatory arrest, and
septicemia.
[0004] Cardiac arrest is a major contributor to global cerebral
ischemia. Cardiac arrest refers to cessation or significant
reduction of a patient's cardiac output and effective circulation
to vital organs, most importantly the brain. Cardiac arrest can
result from a number of causes, such as electrical dysfunction,
mechanical failure, circulatory shock, or an abnormality in
ventilation. Within minutes of blood flow cessation, tissue becomes
ischemic (oxygen deprived), particularly in the heart and brain.
Brain tissue is perhaps most immediately at risk, with severe,
irreversible damage occurring minutes after the initial cardiac
arrest. Patients in cardiac or circulatory arrest are usually
treated by a combination of forced ventilation of the lungs and
forced compression of the heart. Most commonly, cardiopulmonary
resuscitation (CPR) is applied to the patient, with manual chest
compression and mouth-to-mouth resuscitation. Advanced cardiac
support (ACS) may also be provided in the form of drugs,
defibrillation, and other techniques. Less commonly, open chest
massage of the heart may be performed, particularly in a hospital
setting where skilled surgeons may be present. Open chest heart
massage is probably the most effective technique at resuscitating a
patient and avoiding ischemic brain damage, but the technique is
quite invasive and not available in most emergency situations.
[0005] CPR and other techniques which are directed at mechanical
heart compression and lung ventilation do not usually provide
adequate brain oxygenation. In addition, vasoconstrictors, e.g.,
epinephrine, administered during CPR are often either ineffective
or given in dosages too high to produce systemic blood pressure
required for cerebral perfusion. In the best cases, conventional
cardiac resuscitation techniques will provide no more than 1 l/min
of total blood circulation (with only about 200 ml/min passing
through the cerebral vasculature) and no more than 5 to 15 mmHg of
blood pressure. Normal circulation and blood pressure are 5 l/min
and 80 to 100 mmHg, respectively, with about 1 l/min passing
through the cerebral vasculature. Such flows are usually not
adequate at normothermia. Even when CPR techniques are applied
within the first several minutes of a cardiac arrest, the
percentage of patients who survive without significant brain damage
is very low. Significantly, most patients suffering from cardiac
arrest die because of cerebral hypoperfusion.
[0006] Recognizing such problems, alternative techniques for
treating patients in cardiac arrest have been proposed. Of
particular interest to the present invention, the emergency use of
cardiopulmonary bypass machines for supporting and cooling systemic
circulation has been proposed. Generally, access is provided with a
pair of catheters, where one of the catheters may be balloon-tipped
to partition the circulation and permit the desired bypass. While
such systems are theoretically effective, they do not isolate the
cerebral vasculature and do not necessarily provide sufficient
oxygenation of the brain. Moreover, the need to deploy
intravascular catheters is time consuming and must be performed by
a highly skilled and trained personnel.
[0007] Surgical procedures on the aorta are required for the
treatment of a number of conditions, such as aortic aneurysms,
occlusional diseases, aortic dissection, and the like. Exemplary
procedures include conventional aortic aneurysm repair and
grafting, endarterectomy for the treatment of aortic atheroma,
stenting for the treatment of aortic atheroma or dissection, and
the like. Such procedures frequently require that the aorta be
surgically opened to permit reconstruction or other surgical
modification. Surgically accessing and opening the aorta will
usually further require that the patient's circulation be arrested,
i.e., blood flow through the aorta cannot be accommodated while the
aorta is being surgically accessed. Cessation of systemic
circulation places a patient at great risk, particularly in the
cerebral vasculature where ischemia can rapidly lead to
irreversible brain damage.
[0008] A number of techniques have been proposed to at least
partially protect a patient having arrested circulation during a
variety of aortic procedures. It will be appreciated that
conventional cardiopulmonary bypass (CABG) techniques will
generally not be useful when the aorta does not remain in tact.
Thus, various alternative protective protocols have been
proposed.
[0009] Retrograde aortic perfusion (RAP) can be used when a
procedure is being performed on the aorta between the heart and the
aortic arch. The aorta is clamped beneath the aortic arch and
retrograde aortic perfusion established, typically via femoral
access. Advantageously, such retrograde perfusion can continue
throughout the procedure since the operative site within the aorta
is isolated by the clamp. RAP, however, is disadvantageous in a
number of respects. In particular, retrograde perfusion often
results in significant cerebral embolization from dislodgment of
atheromatous material in the descending aorta and aortic arch. Such
risk, as well as the limited region of the aorta that can be
operated on, makes PAP less than ideal. Moreover, RAP is not useful
for procedures distal or proximal to the isolated region of the
aorta and is useful only at the beginning of procedures performed
within the isolated aortic region.
[0010] Another approach for protecting the brain during aortic arch
procedures is referred to as hypothermic circulatory arrest (HCA).
HCA relies on inducing marked hypothermia in the entire body prior
to stopping blood circulation altogether. Circulation remains
stopped during the entire aortic procedure, thus placing the
patient at significant risk of ischemia (despite the hypothermia).
The patient is at further risk because the whole body has been
cooled, thus increasing the duration of the surgery to accommodate
the time needed to return to normal body temperature. HCA has also
been associated with systemic coagulopathy (impaired coagulation)
in a significant number of patients. Coagulopathy can require blood
and plasma transfusion, both of which have been associated with the
risk of viral infection. Aortic surgery performed with HCA has a
very high morbidity, typically about 20%.
[0011] In order to retain some cerebral circulation during the time
the aortic arch is accessed, HCA may be combined with retrograde
cerebral venous perfusion (RCP). A catheter is placed in the
superior vena cava and oxygenated blood introduced. Flow is
established in a retrograde direction up the vena cava into the
brachial and jugular veins. Unfortunately, very little of the
oxygenated blood will reach the cerebral vessels for a number of
reasons. For example, as much as 85% of the blood will enter the
brachial veins and go to the arms with as little as 205 of the
blood entering the brain. Moreover, the jugular venous valves may
inhibit the blood from reaching the cerebral vessels. Blood that
does reach the cerebral veins immediately flows outwardly through
the extensive collateral circulation without perfusing the brain
tissue. The amount of blood that returns to the aorta from the
carotid arteries represents no more than about 5% of the total
blood that is initially introduced to the superior vena cava.
Additionally, as observed by the inventor herein, such retrograde
perfusion results in a build up of the cerebral pressure that
further inhibits any blood inflow. For these reasons, HCA, even
when combined with RCP, falls far short of providing adequate
protection for the patient during procedures performed on the
aorta.
[0012] Another procedure for perfusing the brain during aortic
procedures has recently been proposed. The procedure is referred to
as selective antegrade cerebral perfusion (SCP) and relies on
introducing a catheter through the aorta into a carotid artery in
order to perfuse the cerebral vasculature. Introduction of the
catheter can dislodge atheromatous material which will often be
present at the take-off from the aorta and which may thus cause
cerebral embolization. Furthermore, in order to prevent air from
entering the cerebral vessels, the carotid artery and all other
cerebral arteries must be externally clamped or snared, which can
cause atheromatous embolization. While the procedure can more
effectively maintain cerebral perfusion than HCP, alone or combined
with RCP, the risk of both air and atheromatous embolization more
than outweighs any associated benefits from enhanced perfusion.
[0013] It would therefore be desirable to provide improved methods
and systems for perfusing the cerebral vasculature of a patient
suffering from either focal or global cerebral ischemia with
oxygenated blood or other media in patients. Such methods and
systems should be suitable for rapid deployment, be capable of use
outside of a hospital environment, and should be capable of being
performed with less skilled personnel than comparable
catheter-based systems. Preferably, such systems may be deployed
via direct percutaneous cannulation of the patient vasculature. In
addition, the method and systems of the present invention should be
suitable for use with patients undergoing cardiac and vascular
procedures where it is desirable to perfuse and/or isolate the
cerebral vasculature. At least some of these objectives will be met
by the invention of the present application.
[0014] For these reasons, it would be desirable to provide improved
methods, systems, and kits for protecting the brain and cerebral
vasculature during the performance of surgical procedures on the
aorta. In particular, it would be desirable to provide for cerebral
perfusion which is both antegrade and continuous throughout
performance of the aortic procedure and which would enable profound
cerebral hypothermia without systemic hypothermia. It would be
further desirable to provide for improved isolation of the cerebral
vasculature, still more preferably with minimum and ideally no
external clamping. It would be still further desirable to minimize
the risk of air and/or atheromatous embolization in the cerebral
vasculature or elsewhere as a result of the aortic procedure. Such
methods, systems, and kits should be compatible with reduced and/or
localized hypothermia, particularly hypothermia directed
specifically at the cerebral vasculature. In addition, cerebral
isolation, perfusion and cooling should be compatible with systems
and methods for perfusing non-cerebral portions of the patient's
vasculature. At least some of these objectives will be met by the
invention described hereinafter.
DESCRIPTION OF THE BACKGROUND ART
[0015] Selective cerebral perfusion (SCP) procedures are described
in Kazui et al. (1992) Ann. Thorac. Surg. 53:109-114; Mohri et al.
(1993) Ann. Thorac. Surg. 56:1493-1496; and Tanaka et al. (1995)
Ann. Thorac. Surg. 59:651-657. Advanced cardiac life support
techniques are discussed and compared in Tucker et al. (1995) Clin.
Cardiol. 18:497-504. Emergency cardiopulmonary bypass using access
needles introduced via a cut-down procedure is described in Litzie,
U.S. Pat. No. 4,540,399. Emergency cardiopulmonary bypass using
catheter-based access is described in Safar et al., U.S. Pat. No.
5,383,854; Safar et al., U.S. Pat. No. 5,308,320; Buckberg et al.,
U.S. Pat. No. 5,011,469; and Safar (1993) Ann. Emerg. Med.
22:58/324-83/349. A cardiopulmonary bypass system with cooling
having a balloon tipped cannula for accessing the inferior vena
cava and an anastomotically attached catheter for accessing the
femoral artery is described in Sausse, U.S. Pat. No. 3,881,483.
Cerebral infusion with cooled and/or preservative media is
described in Klatz et al., U.S. Pat. Nos. 5,149,321; 5,234,405;
5,395,314; 5,584,804; and 5,653,685. Aortic perfusion with balloon
catheters is described in Paradis, U.S. Pat. No. 5,334,142;
Manning, U.S. Pat. No. 5,437,633; and Manning et al. (1992) Ann.
Emerg. Med. 21:28-35. Coronary and/or cerebral retroperfusion is
described in Pizon et al., U.S. Pat. No. 4,459,977; Jackson, U.S.
Pat. No. 4,850,969; Jackson, U.S. Pat. No. 4,917,667; and Grady,
U.S. Pat. No. 5,084,011. Other relevant patents include Barkalow et
al., U.S. Pat. No. 4,198,963; Ward et al., U.S. Pat. No. 5,531,776;
and Meyer, I I I, U.S. Pat. No. 5,626,143.
SUMMARY OF THE INVENTION
[0016] According to the present invention, methods, systems, and
kits are provided for perfusing an oxygenated medium, usually
autologous blood, through the cerebral vasculature of patients
suffering from global ischemia caused by, e.g., cardiac arrest,
shock, circulatory arrest, and septicemia; focal ischemia caused by
stroke, subarachnoid hemorrhage spasms, iatrogenic vasospasm; or,
cerebral edema, e.g., head trauma. The method, systems, and kits
are useful not only in providing selective isolated cerebral
perfusion during all conditions of cerebral ischemia, but also in
reducing the dosage of vasoconstrictors required to achieve a
desired perfusion pressure.
[0017] Optionally, in addition to improving cerebral perfusion, the
methods of the present invention may combine or otherwise rely on
cooling of the patient's head and cerebral vasculature in treatment
of both global and focal cerebral ischemia to inhibit tissue damage
resulting from lack or limitation of cerebral blood circulation.
Usually, the oxygenated medium which is circulated as part of the
methods of the present invention will be cooled in order to cool
the brain tissue and reduce the risk of ischemic damage. Further
optionally, the patient's head may be cooled even prior to
initiating perfusion of externally oxygenated, optionally cooled
blood. In some instances, the cooled blood can be used to
externally cool the patient's head during the treatment protocol,
e.g., by passing the blood through a helmet or other structure
which permits the blood to selectively cool the head. This
selective isolated cooling of the head and/or cerebral vasculature
is desirable and preferred over systemic cooling, since
coagulopathy, poor healing, cardiac arrhythmia and cardiac arrest
can ensue as a result of systemic cooling.
[0018] The methods of the present invention for improving cerebral
perfusion comprise accessing at least one extracranial vein, such
as the internal jugular vein, the femoral vein, and/or the
subclavian vein, and accessing at least one artery which feeds the
cerebral vasculature through incisions on any extracranial artery,
such as the common carotid artery, the internal carotid artery, the
femoral artery, or the subclavian artery. In providing both
selective isolated perfusion and cooling of the cerebral tissue,
the methods comprise assessing at least one thing at location(s)
which drain at least a portion of the cerebral vasculature, such as
the internal jugular vein and/or external jugular vein, and
assessing at least one artery which feeds the cerebral vasculature
through incisions on any extracranial artery, such as the common
carotid artery, the internal carotid artery, the femoral artery, or
the subclavian artery. In emergency cases, access will usually be
provided by a percutaneous needle stick as described in more detail
below. When performed in conjunction with aortic arch or other
cardiac surgery, in contrast, the access will usually be provided
via surgical exposure of the target vein(s) and artery(ies). An
oxygenated medium is flowed from the arterial access location
through the cerebral vasculature to the venous access location in
order to perfuse the cerebral vasculature with the oxygenated
medium. The vein(s) and artery(ies) are chosen to provide access to
at least a major portion of the blood circulation through the
cerebral vasculature. Preferably, the vein(s) and artery(ies) will
also be directly accessible via a percutaneously inserted needle or
other cannula for emergency performance of the procedures in the
field. Suitable veins include the internal and/or external jugular
vein, the superior vena cava, and the like. Suitable arteries
include the common carotid arteries, the external and internal
carotid artery, and the like. The particular access sites in each
of the artery and vein will be selected based primarily on
percutaneous accessibility. Preferred venous access sites lie
within the internal jugular vein and preferred venous access sites
lie within the common carotid artery.
[0019] After access is established, typically using percutaneously
introduced needles, cannulas, or other conduits, a flow of
oxygenated medium is initiated at a rate sufficient to provide
oxygen to the brain tissue. The rate will depend on the amount of
oxygen being carried by the oxygenated medium, typically being in
the range from 0.1 l/min to 1.5 l/min, typically from 0.2 l/min to
1 l/min. For oxygenated autologous blood, the rate will typically
be in the range from 0.2 l/min to 1 l/min. In some instances, in
order to inhibit possible reperfusion injury, it will be desirable
to initiate the flow rate of oxygenated medium at a relatively low
rate and subsequently increase the flow rate to a final rate within
the ranges set forth above. Usually, the final flow will be
maintained at a steady rate, but it will also be possible to
initiate a pulsatile or other non-steady flow rate.
[0020] In order to enhance the efficiency of oxygenated medium
delivered to the cerebral vasculature, it will usually be desirable
to at least partly occlude the access blood vessel(s) near the
access sites in order to prevent flow away from the cerebral
vasculature. That is, at the venous access site(s), the vein will
be occluded in order to inhibit flow caudal to the access location.
At the arterial access site(s), the artery will be occluded to
inhibit flow into the aorta. As described in more detail in
connection with the systems of the present invention, such
occlusion will typically be provided by inflatable occluding
balloons on the access needles, cannulas, or other conduits.
[0021] In the preferred methods of the present invention, the
oxygenated medium will consist essentially of blood, usually
patient autologous blood, and the blood will be recirculated from
the venous access location to the arterial access location using a
pump. In addition to the primary antegrade flow, some flow may
occur in a retrograde direction to the contralateral hemisphere
and/or posterior territories as well. The blood will be
extracorporeally oxygenated and optionally cooled, typically to a
temperature in the range from 7.degree. C. to 35.degree. C.
External pumping, oxygenation, and cooling can be provided by
systems of a type used for cardiopulmonary bypass procedures.
[0022] Alternatively, the oxygenated medium may comprise a
synthetic oxygen carrier, such as a perfluorocarbon, or other
synthetic blood substitute material. In some instances, such
synthetic oxygen carriers may be combined with patient or
non-autologous blood. The synthetic oxygen carriers may be
preoxygenated and flowed through the cerebral vasculature only
once. In such cases, a large reservoir of the synthetic oxygen
carrier may be provided, passed through the cerebral vasculature,
and collected as it passes out of the venous access site.
Alternatively, the synthetic oxygen medium, optionally combined
with blood, may be extracorporally recirculated and oxygenated as
described above for autologous blood.
[0023] In all cases, the oxygenated medium may have other
biologically active agents combined therewith. For example, drugs
and biological agents which inhibit deterioration of brain tissue
in cases of limited oxygen supply may be utilized. Such
compositions include NMDA receptor-inhibitors, calcium-channel
blockers, anticoagulants, glutamate inhibitors, free-radical
inhibitors, vasodilators, and the like.
[0024] The present invention still further provides improved
methods for selective isolated cerebral perfusion in patients with
global or focal ischemia. Such improved methods comprise isolating
at least a portion of the patient's cerebral vasculature from the
remainder of patient circulation, typically by partitioning using
occlusion balloons as described in more detail hereinafter. Patient
blood is oxygenated and recirculated through the isolated
vasculature in order to inhibit ischemia and resulting damage to
brain tissue while steps are taken to treat the cardiac arrest.
[0025] In yet another aspect of the method of the present
invention, improved antegrade cerebral perfusion with an oxygenated
medium comprises introducing the oxygenated medium, typically
autologous blood, to a carotid artery to establish antegrade flow
into the cerebral vasculature. The oxygenated medium, after it has
passed through the cerebral vasculature, is collected through a
jugular vein. Such improved methods may be used with both
once-through perfusion using a synthetic oxygen carrier and/or
heterologous oxygenated blood. More usually, such improved methods
will be used with extracorporeal recirculation and oxygenation of
autologous blood.
[0026] Systems according to the present invention for recirculating
and oxygenating blood in the cerebral vasculature of a patient
comprise a venous cannula, an arterial cannula, a pump, and an
oxygenator. The venous cannula typically has a lumen diameter in
the range from 2 mm to 4 mm and includes a distal occlusion
balloon, wherein the cannula and balloon are sized to access and
occlude a vein which drains the cerebral vasculature, typically a
jugular vein. The arterial cannula typically has a lumen diameter
in the range from 2 mm to 4 mm and also has a distal occlusion
balloon, and the cannula and balloon are sized to access and
occlude an artery which feeds the cerebral vascular, typically the
common carotid artery. The pump may be connected between the venous
cannula and the arterial cannula to circulate blood from the venous
cannula to the arterial cannula, typically at a flow rate in the
ranges set forth above. The oxygenator processes the externally
circulating blood to provide a desired degree of oxygenation, also
within the ranges set forth above.
[0027] The present invention still further provides kits including
a venous cannula sized to access a vein which drains the cerebral
vasculature and an arterial cannula sized to access an artery which
feeds the cerebral vasculature. Such kits will further include
instructions for use according to any of the methods set forth
above. Additionally, the kits may comprise a package for holding
all or a portion of the kit components, typically in a sterile
condition. Typical packages include trays, pouches, boxes, tubes,
and the like. Preferably, the cannulas will each have an occlusion
balloon sized to occlude the respective blood vessel lumen into
which they are placed. Other optional kit components include
oxygenated medium, drugs to be delivered via the flowing blood or
other oxygenated medium, catheters for connecting the cannulas to
an extracorporeal recirculation/oxygenation cooling system,
cassettes for use with such extracorporeal recirculation systems,
cooling elements, thermometers, pressure transducers, and the
like.
[0028] In still other embodiments, methods, systems, and kits are
provided for isolating and perfusing the cerebral vasculature,
usually to facilitate access to a patient's aorta, during
performance of a diagnostic or interventional procedure on the
aorta, more usually during performance of an open surgical
interventional procedure on the aorta, such as repair of an aortic
aneurysm, dissections, reconstruction of the aorta, endarterectomy,
or the like. The heart will usually be arrested during open
surgical procedures where the aorta is opened and procedure is
performed within the lumen of the aorta. In some instances,
however, the heart may remain beating while the procedure is
performed intravascularly, i.e. through using catheters and other
instruments introduced from the peripheral vasculature and into the
aorta. The methods of the present invention will serve primarily to
isolate the cerebral vasculature and prevent gaseous and
atheromatous emboli from entering the cerebral vasculature while
the vasculature is perfused with an oxygenated medium.
[0029] Methods according to the present invention comprise
internally occluding blood flow to the arterial cerebral
vasculature at a location(s) above the aortic arch. At a minimum,
blood flow to the right cerebral vasculature will be internally
occluded. Preferably, blood flow to both the right and left
cerebral vasculature is internally occluded. Such internal
occlusion is usually accomplished using an expansible occluder or
partial occluder with central lumen, such as an inflatable balloon
positioned at the distal end of a catheter, cannula, or other
access device. The access device further provides for perfusion of
an oxygenated medium into the occluded artery distal to the point
of occlusion, e.g., the device may have a lumen that delivers the
medium at a suitable positive pressure.
[0030] Occlusion of blood flow from the aortic arch and perfusion
of oxygenated medium to the arterial cerebral vasculature may be
accomplished in a number of ways, e.g., by occluding the right
common carotid artery or by occluding an upstream portion of the
brachiocephalic artery which-feeds the right carotid artery. In
both cases, the oxygenated medium can be perfused distally of the
balloon or other occluding device so that it flows up through the
right common carotid artery into the cerebral vasculature. When
occluding the brachiocephalic artery and perfusing the oxygenated
medium upstream of the right common carotid artery, it may be
desirable to at least partially inhibit blood flow through the
right subclavian artery, e.g. using another occluding balloon or
using an externally applied tourniquet on the arm. Inhibiting the
loss of oxygenated medium to the arm helps redirect the medium to
the cerebral arterial vasculature through both the right common
carotid artery as well as the right vertebral artery, assuming that
the subclavian artery is occluded at a point distal to the
vertebral arterial branch. Other, more complex occlusion patterns
could also be employed, although not necessarily being
preferred.
[0031] Occlusion of blood flow from the aortic arch and perfusion
of oxygenated medium to the left arterial cerebral vasculature may
be effected within the left common carotid artery, the left
subclavian artery, and/or the left vertebral artery. When blood or
other oxygenated medium is introduced into the left subclavian
artery, it may further be desirable to inhibit blood flow into the
arm, e.g., by internally or externally occluding the left
subclavian artery at a point that prevents such blood flow.
[0032] In a presently preferred procedure, occluding balloons will
be positioned within the brachiocephalic artery, the left common
carotid artery, and the left subclavian artery. Both the right
subclavian artery and the left subclavian artery will be blocked,
preferably with external tourniquets on the arms. Blood or other
oxygenated medium will then be perfused into the arterial cerebral
vasculature to points immediately upstream of each of the occluding
balloons, preferably using lumens or other infusion components
incorporated within the occluding devices themselves. Inhibition of
blood flow down into the arms is beneficial since it redirects the
blood or other oxygenated medium back into the cerebral arterial
vasculature. While this approach may be optimal in many ways, the
present invention can be carried out in other ways as well. Most
simply, internal occlusion of the right brachiocephalic artery and
perfusion of oxygenated medium distal to the point of occlusion may
be sufficient in some cases by itself.
[0033] In many cases, it will be desirable to occlude the arteries
at a point as close to the aortic arch as possible. In particular,
this is true of the brachiocephalic artery, the left carotid
artery, and the left subclavian artery which branch directly from
the aortic arch. Occlusion close to the aortic arch (i.e.,
immediately above the branch or within 3 cm thereof) is of benefit
primarily because it enables the surgeon to access the artery and
initiate the occlusion with minimal aortic dissection toward the
neck. In other cases, of course, it will be possible to access any
one of the brachiocephalic artery at a point close to the aortic
arch and to intravascularly advance an occluding balloon or other
devise to a desired point of occlusion. In some instances, it may
even be desirable to deliver and position devices carrying multiple
occluding balloons and/or lumens for delivering oxygenated medium
to the cerebral arterial vasculature.
[0034] Access to the occlusion site and the target artery may be
obtained in a variety of ways. For example, the target artery may
be surgically exposed when the chest and neck are opened as part of
a procedure being performed on the aortic arch. In such cases,
small incisions can be made directly into the wall of the target
artery to permit introduction of the occluder. Alternatively, in
procedures that are performed away from the aortic arch and/or
where it is not desired to surgically open the patient above the
target sites within the arteries, the target sites can be accessed
by conventional cut-down procedure or a needle-based procedure,
such as the Seldinger technique. As yet another alternative, the
arterial vasculature can be accessed at a point remote from the
desired point of occlusion, e.g. in the femoral artery or in an
artery of the arm, such as the axillary or brachial artery. The
balloon or other occluding member on the catheter may then be
intravascularly advanced from the access location to the desired
point of occlusion in a conventional manner, e.g. over a guidewire
under fluoroscopic observation. An approach to a desired occlusion
point within the brachiocephalic artery and/or the right common
carotid artery from an artery in the arm may be preferred since no
catheter would be present in the aortic arch itself.
[0035] The oxygenated medium will usually be blood, more usually
being autologous blood obtained from the patient being treated. In
the most usual cases, patient blood will be recirculated through a
conventional blood pump and oxygenator so that the patient may be
continuously supplied with oxygen in the perfused cerebral
vasculature. The blood or other oxygenated medium will also be
cooled in order to induce selective hypothermia within the cerebral
vasculature. A preferred hypothermic temperature for the brain will
be in the range from 7.degree. C. to 35.degree. C., more preferably
from 9.degree. C. to 30.degree. C. The actual temperature that is
maintained will depend both on the temperature and the flow rate of
the oxygenated medium, with higher flow rates generally requiring
less cooling to achieve the target hypothermic temperature. Useful
flow rates for the oxygenated medium will be in the range from 300
ml/minutes to 1500 ml/minutes, typically from 400 ml/minute to 1000
ml/minute without hypothermia, and from 80 ml/minute to 600
ml/minute, typically from 150 ml/minute to 400 ml/minute with
hypothermia induced in the patient. Generally, the patient requires
progressively less oxygen with increased hypothermia, allowing the
flow rates of oxygenated cooled medium to be decreased. A
sufficient flow of the oxygenated medium should be maintained,
however, in order to maintain the desired level of hypothermia.
Suitable temperatures will be in the range from 8.degree. C. to
35.degree. C., typically from 14.degree. C. to 30.degree. C. It
will be appreciated, of course, that the values of temperature,
flow rate, and degree of oxygenation will be quite interdependent
in that particular optimum values might be selected for individual
patients and/or for different procedures.
[0036] The methods of the present invention will-find their
greatest use in open and thoracoscopic surgical procedures where
the aorta is exposed and surgically opened to permit performance of
the desired procedure. In such cases, the heart will be arrested
and the perfusion of the oxygenated medium will be relied on to
achieve adequate oxygenation of the brain tissue and to avoid
deleterious ischemia. Generally, the flow rates and temperatures
set forth above will be sufficient to both achieve adequate
perfusion and avoid ischemia. After the open procedure is
completed, and the aorta is surgically closed, heart function may
be reestablished. In order to avoid the release of emboli from the
aorta into the cerebral vasculature, occlusion of carotid
artery(ies) will be maintained for a minimum amount of time after
heart function has been reestablished, typically for at least about
2 minutes, preferably for at least about 5 minutes, in order to
permit atheromatous debris and air to be cleared from the aorta and
away from the brain.
[0037] Occlusion of the selected arteries with the expansible
occluder may be achieved in a variety of ways. Usually, in open
surgical procedures, the outside of the target artery(ies) will be
surgically exposed, permitting surgical incisions through the
arterial wall(s). The expansible occluder may then be introduced
through the incision, expanded, and perfusion of oxygenated medium
established through the occluder. Alternatively, the expandable
occluders may be introduced percutaneously through the patient's
neck and to the selected artery(ies) using conventional access
techniques, such as the Seldinger technique. The expansible
occluders will typically but not necessarily include catheters,
cannulas, or other devices that permit the perfusion of the
oxygenated medium through the expansible member and into the
carotid artery for perfusion of the cerebral vasculature. It will
also be possible to utilize separate devices for occlusion and for
the perfusion of oxygenated medium. Fore example, it would be
possible to employ an external clamp on the target artery and to
utilize a separate needle or other cannula for infusion the
oxygenated medium upstream of the clamp. The use of clamps,
however, is generally not preferred since they can cause the
release of significant amounts of atheromatous debris when
released. It would also be possible to employ separate occluder(s)
and infusion needles/cannulas, where the points of occlusion and
infusion of oxygenated medium could be close together or
spaced-apart. Also, as mentioned above, it will be possible to
employ devices with more than one occlusion balloons and/or more
than one infusion lumens in order to occlude and/or infuse
oxygenated medium to different points in the vasculature from a
single incision site.
[0038] As an alternative to access at points in the arterial
vasculature above the aortic arch, the occlusion and perfusion
devices may be introduced intravascularly through sites remote from
the aortic arch. Most commonly, intravascular catheters may be
introduced by conventional techniques through the femoral arteries
and advanced to the target cerebral arteries using conventional
techniques. Such access routes, will necessarily involve passing
the catheters through the aortic arch itself. Thus, in many
instances, it will be undesirable to use such intravascular
techniques since they will lie within the regions where the
procedure is being performed. Intravascular access could also be
achieved in a retrograde manner through the axillary and brachial
arteries as discussed above.
[0039] While it will be possible to perfuse a cold, oxygenated
medium without collecting and recycling the medium, it will usually
be desirable to establish a continuous extracorporeal flow circuit
for filtering, oxygenating, and returning patient blood or other
oxygenated medium to the patient. The oxygenated medium perfused
into the arterial cerebral vasculature will generally flow through
the anterior and posterior regions of the brain and into the venous
system of the brain. From the venous system, the oxygenated medium
will flow outwardly from the brain, primarily from the jugular
veins. Thus, it will be convenient to collect the oxygenated medium
from the brain from at least one of the right and left internal
jugular veins, preferably from both internal jugular veins, or from
the superior vena cava into which the jugular veins drain. This
blood can then be returned to the extracorporeal blood pump,
oxygenated, and cooled before return to the patient's arterial
cerebral vasculature. Additionally, a very small portion of the
blood or other oxygenated medium perfused into the brain through
the cerebral arteries may leak back into the aortic arch through
the left vertebral artery if the left subclavian artery is not
occluded. This leakage, typically in an amount from 5 ml/minute to
25 ml/minute, can be suctioned or otherwise collected by the
surgeon and returned to the extracorporeal circulation system.
[0040] The brain and cerebral vasculature are at greatest risk from
embolization and ischemia during the performance of aortic
procedures that require arresting of the heart. Other portions and
tissues within the body, however, are also at significant risk and
in some cases it may be desirable to establish a perfusion of
oxygenated medium through the noncerebral vasculature, in
particular the vasculature in the lower portion of the patient's
body. For example, oxygenated blood or other medium can be
introduced into the aorta below the aortic arch, where the aortic
arch is isolated using an expansible occluder or other conventional
occlusion device. The oxygenated medium will thus flow to the lower
portion of the patient's body where it will collect in the venous
system and be returned towards the patient's heart through the
inferior vena cava. By occluding the inferior vena cava, again
typically using an expansible occluder, the blood or other
oxygenated medium may be collected and returned to an
extracorporeal oxygenation, pumping, and optional cooling
circuit.
[0041] The present invention still further provides kits including
one or more expansible occluders adapted to occlude selected
artery(ies) as described above. Such kits will further include
instructions for use according to any of the methods set forth
above. Additionally, the kit may comprise a package for holding all
or a portion of the kit components, typically in a sterile
condition. Typical packages include trays, pouches, boxes, tubes,
and the like. Preferably, the cannulas will each have an occlusion
balloon sized to occlude the respective blood vessel lumen into
which they are placed. Other optional kit components include
oxygenated medium, drugs to be delivered via the flowing blood or
other oxygenated medium, catheters for connecting the cannulas to
an extracorporeal recirculation/oxygenation cooling system,
cassettes for use with such extracorporeal recirculation systems,
cooling elements, thermometers, pressure transducers, and the
like.
BRIEF DESCRIPTION OF THE DRAWINGS
[0042] FIG. 1 is a schematic illustration of a patient's head
illustrating arterial and venous access sites suitable for use in
the methods of the present invention.
[0043] FIGS. 2A and 2B illustrate the use of a pair of access
cannulas for perfusing oxygenated medium through the cerebral
vasculature of a patient according to the methods of the present
invention.
[0044] FIG. 3 illustrates a preferred system constructed in
accordance with the principles of the present invention.
[0045] FIG. 4 illustrates an exemplary kit constructed in
accordance with the principles of the present invention.
[0046] FIG. 5 illustrates the great vessels that exit and enter the
heart and which are relevant to the occlusion and circulation
patterns of the present invention.
[0047] FIGS. 6A-6E illustrate the use of differing arrangements of
expansible occluders for occluding and directing the flow of
oxygenated medium to the cerebral arteries according to the methods
of the present invention.
[0048] FIG. 7 illustrates the occlusion pattern of FIG. 6, with
further occlusion of the internal jugular veins to collect
oxygenated medium flowing from the venous structure of the
brain.
[0049] FIG. 8 illustrates an alternate occlusion pattern for
collecting oxygenated medium from the brain, where the superior
vena cava is occluded and all medium flowing into the superior vena
cava collected.
[0050] FIG. 9 illustrates an occlusion pattern according to the
present invention where the lower vasculature of the patient is
occluded and perfused with oxygenated medium.
[0051] FIG. 10 is a schematic illustration of a patient undergoing
an aortic procedure with an oxygenated medium being supplied
according to the scheme set forth in FIGS. 8 and 9.
[0052] FIG. 11 illustrates a kit constructed in accordance with the
principles of the present invention.
DESCRIPTION OF THE SPECIFIC EMBODIMENTS
[0053] The present invention provides methods, systems, and kits
for perfusing the cerebral vasculature of a patient with an
oxygenated medium. For the purposes of the present invention, the
cerebral vasculature includes all arteries and veins leading into
or from the patient's head, particularly including the common
carotid arteries, the external and internal carotid arteries, and
all smaller arteries which branch from the main arteries leading
into the head. In some cases, particularly in open surgical
procedures, access may be established in the aortic arch and
innominate (brachycephalic trunk) artery as well. Cerebral veins
include the external and internal jugular veins, the superior vena
cava, and the smaller veins which feed into the primary veins
draining the cerebral vasculature. Preferred access points should
be at locations in the vasculature which permit relatively direct
percutaneous introduction of a needle, cannula, or other access
conduit through which the flow of oxygenated medium will be
established. Exemplary access sites are in those regions of the
internal jugular vein IJV and common carotid artery CCA which are
readily located and accessed through a patient's neck, as
illustrated in FIG. 1.
[0054] Usually, only a single arterial and a single venous site
need be accessed. Blood or other oxygenated medium perfused at a
flow rate of at least 0.2 l/min (preferably at least 0.5 l/min)
will usually be sufficient to go up from the arterial access site,
e.g., through either the right or left common carotid artery,
perfuse the ipsilateral hemisphere, and to cross over and perfuse
the contralateral hemisphere of the brain. Suitable perfusion
pressures are in the range from 250 mmHg, preferably from 30 mmHg
to 160 mmHg. The ipsilateral hemisphere will thus be perfused in an
antegrade direction while the contralateral hemisphere and
territories supplied by the posterior circulation will be perfused
in a retrograde direction. The blood will then flow into the
cerebral venous vasculature from where it may be collected at one
or two venous access sites. In this way, the entire brain can be
perfused with oxygenated and optionally cooled blood or other
oxygenated medium.
[0055] As illustrated in FIGS. 2A and 2B, access will usually be
established using cannulas 10 and 20, each having inflatable
isolation balloons 12 and 22 near their distal ends, respectively.
In the illustrated embodiment, the cannulas 10 and 20 are needles
having sharpened distal tips such that the needles may be
penetrated through the patient's skin S without the need to employ
separate stylets, needles, or other access means. The treating
personnel are thus able to locate the appropriate access points on
the patient's neck or other location and directly introduce the
cannulas 10 and 20 so that their distal tips lie within the lumens
of the artery A and vein V, respectively. Alternatively, the
treating professional may access the artery and/or vein through a
small incision or puncture allowing introduction of a blunt cannula
or other access tube.
[0056] Once the cannulas 10 and 20 have been placed, as illustrated
in FIG. 2A, the balloons 12 and 22 will be inflated, as illustrated
in FIG. 2B. The balloons and 12 and 22 partition the cerebral
vasculature so that oxygenated medium introduced through the
arterial cannula 10 will travel upwardly into the cerebral
vasculature and will be inhibited from flowing downwardly to the
arterial system below the head. Similarly, the balloon 22 on the
venous cannula 20 will prevent the outflow of blood or other
oxygenated medium from the cerebral vasculature from flowing
downwardly from the head, allowing efficient collection of the
outflow by the cannula 20.
[0057] In the simplest cases, the methods of the present invention
may rely on providing relatively large volumes of oxygenated
medium, such as a pre-oxygenated carrier, such as a
perfluorocarbon, or pre-oxygenated heterologous blood, and flowing
the oxygenated medium through the arterial cannula 10, through the
cerebral vasculature, and out the venous cannula 20 in a
once-through manner. The oxygenated medium passing out of the
venous cannula will not be recirculated.
[0058] More typically, however, the methods of the present
invention will rely on circulating the oxygenated medium from the
venous cannula 20 back to the arterial cannula 10. To circulate the
oxygenated medium, it will usually be necessary to oxygenate the
medium externally of the patient, further usually being desirable
to also cool the medium to lower the temperature of the brain. Such
external oxygenation and optional cooling may be provided by a
system 50 as illustrated in FIG. 3. The system 50 includes a pump
52, typically a peristaltic pump, a cooler 54, a temperature gauge
56, and a port 58 for infusing cerebral protective agents and/or
other drugs or biologically active substances. Such systems are
analogous to the cardiopulmonary bypass systems used in heart and
vascular surgery. Suitable portable bypass pumps and oxygenators
are described in U.S. Pat. No. 4,540,399; U.S. Pat. No. 5,011,469;
and U.S. Pat. No. 5,149,321, the full disclosures of which are
incorporated herein by reference. The systems described in these
patents, however, are generally intended for maintaining artificial
circulation through all or a substantial portion of the patient's
entire vasculature. The systems of the present invention will
generally be modified to provide blood or other oxygenated medium
at lower flow rates within the ranges set forth above.
[0059] Optional features of the cannulas 10 and 20 illustrated in
FIG. 3 include separate inflation conduits 13 and 23 for inflating
balloons 12 and 22, respectively. The inflation conduits may be
connected to syringes or other conventional devices for selectively
inflating the balloons after the cannulas 10 and 12 have been
properly positioned within the target blood vessels. Additionally,
ports 14 and 24 may be provided near the sharpened distal tips of
the cannulas 10 and 12, respectively. Alternatively, the distal
tips of the cannulas could simply have a chamfered, sharpened
distal tip where flow passes directly out the tip. As a further
alternative, the cannulas 10 and 12 could be provided with simple
stylets which permit self-introduction. After introduction, the
stylets could be quickly removed to provide an open flow lumen at
the tip.
[0060] Referring now to FIG. 4, kits according to the present
invention will comprise at least cannulas 10 and 20 and
instructions for use (IFU) 75. The cannulas 10 and 20 will be
suitable for connection to an extracorporeal flow system 50, or for
connection to a reservoir of oxygenated medium, depending on the
intended use. The instructions for use 75 will set forth any of the
methods described above. Usually, the catheters 10 and 20 and
instructions for use 75 will be packaged together in a suitable
package 80, such as a pouch, tray, box, tube, or the like.
Optionally, the instructions for use may be printed in whole or in
part on a portion of the packaging 80. Usually, at least the
catheters 10 and 20 will be sterilely maintained within the package
80. Other optional kit components which could be placed within the
package 80 include oxygenated medium, cerebral protective agents
and/or other drugs, additional catheters for connecting the
cannulas to system 50 or other extracorporeal apparatus,
replaceable cassettes for system 50 which permit replacement of all
system components which directly contact the blood, and the
like.
[0061] Referring now to FIG. 5, systemic circulation relevant to
the methods of the present invention will be briefly described.
Oxygenated blood from the heart normally flows upwardly through the
aortic arch and then downward to the lower portions of the body
through the thoracic aorta. Three major arteries extend upwardly
from the top of the aortic arch. The brachiocephalic artery
branches into the right carotid artery and the right subclavian
artery. In contrast, the left carotid artery and left subclavian
artery extend directly from the aortic arch and do not have a
common portion. Together, the right common carotid artery and left
common carotid artery provide oxygenated blood to most parts of the
head and neck. They ascend through the anterior neck just lateral
to the trachea and are covered by relatively thin muscles which
permits direct percutaneous access via cut-down or needle
introduction (the Seldinger technique) in certain embodiments of
the present invention. In addition to the carotid arteries,
oxygenated blood is provided to the brain through the vertebral
arteries, although to a significantly lesser extent.
[0062] As will be described in more detail below, the methods of
the present invention will rely on internally occluding blood flow
from the aortic arch to at least one common carotid artery, and
preferably both common carotid arteries. Occlusion of blood flow
from the aortic arch to the right common carotid artery may be
effected by occluding the blood flow lumen in the brachiocephalic
artery and/or the right common carotid artery itself. Occlusion of
the left common carotid artery will take place in a lumen of the
left common carotid artery itself, and optionally either or both of
the right and left vertebral arteries may also be directly or
indirectly occluded. Blood or other oxygenated medium will be
provided to the cerebral arterial vasculature through at least some
of the occluded arteries by perfusing a medium to the artery(ies)
at a point distal to the occlusion. As the carotid arteries supply
most of the blood flow to the brain, it will not be necessary to
occlude the vertebral arteries and/or provide oxygenated blood to
the brain through the vertebral arteries. While some leakage of
blood back to the aorta may occur through the vertebral arteries,
such leakage is minor and can be removed from the aortic arch using
conventional suction devices.
[0063] By occluding blood flow to the right common carotid artery
using an occluder present in the brachiocephalic artery, blood
supplied distal to the occluder will flow to both the right common
carotid artery and the right vertebral artery. Thus, it will
usually be preferred to occlude flow to the right common carotid
artery at a point within the brachiocephalic artery. It will be
appreciated, of course, that by providing the perfusion of
oxygenated medium distally of the brachiocephalic artery, blood
will flow not only to the right common carotid artery and right
vertebral artery, but also toward the arm through the right
subclavian artery. Thus, in order to inhibit the flow of oxygenated
medium to the arm and redirect such flow to the cerebral arteries,
it will in some cases be desirable to provide a tourniquet on the
right arm. Alternatively, an occlusion balloon could be located
within the lumen of the right subclavian artery to point downstream
from the right vertebral artery branch. Optionally, a catheter
having a pair of balloons could be used, where one balloon occludes
within the brachiocephalic artery and a second, more distal balloon
occludes within the right subclavian artery.
[0064] Occlusion of the left vertebral artery may be effected in
either the left subclavian artery, usually at a point near the
branch with the aortic arch, or within the left vertebral artery
itself. Occlusion within the left subclavian artery is generally
preferred since it will inhibit passage of atheromatous material
into the entire arterial structure branching from the left
subclavian artery. Moreover, by perfusing oxygenated medium beyond
the point of occlusion, that medium will flow into the left
vertebral artery to supply the left cerebral arterial vasculature.
Loss of blood to the patient's arm can be inhibited by applying a
tourniquet to the left arm.
[0065] The venous system of the brain drains primarily through the
right internal jugular vein and the left-internal jugular vein.
These veins, in turn, drain into the superior vena cave where the
oxygen-depleted blood is returned to the heart. Blood supplied to
the lower body through the thoracic aorta returns to the heart
through the inferior vena cava.
[0066] Referring now to FIG. 6A, a first exemplary method for
accessing an aorta according to the present invention comprises
internally occluding the right common carotid artery at a point
above the aortic arch. Typically, the occlusion may be achieved
using expansible occluders, such as balloon-tipped cannula 10 that
is placed in a lumen of the right common carotid artery. The
balloon may be any conventional type of balloon commonly used for
blood lumen occlusion, e.g., being elastomeric balloons having a
generally spherical geometry. The balloons will be expandable to a
size in the range from 3 mm to 20 mm, typically at a relatively low
inflation pressure on the order of 2 atmospheres to 5 atmospheres.
The expansible occluders may be introduced surgically,
percutaneously, or intravascularly, as discussed above.
[0067] Most commonly, the surgeon accessing the aorta will extend
the incision so that the exterior surfaces of each carotid artery
are exposed. A small surgical incision can then be made and the
exposed wall of the artery and the occlusion balloon introduced in
a conventional manner. Alternatively, the balloon may be
percutaneously introduced via a cut-down procedure or using a
needle, guidewire, and appropriate insertion sheath using
conventional techniques, such as the Seldinger technique. In all
cases, after occlusion is achieved, the oxygenated medium may be
introduced through the cannula, typically within the flow rate and
temperature ranges set forth above. It will also be desirable to
monitor and control the pressure of the oxygenated medium being
introduced, typically within a range of about 10 mmHg to 200 mmHg,
preferably from 30 mmHg to 90 mmHg. The blood may be introduced in
a continuous, non-pulsatile flow.
[0068] By occluding only the right common carotid artery, as shown
in FIG. 6A, the oxygenated medium will be provided only to the
right arterial cerebral vasculature. Moreover, as none of the right
vertebral artery, left common carotid artery, nor left vertebral
artery are occluded, those arteries are placed at risk at receiving
atheromatous material, particularly when heart function is
reestablished. Thus, it will frequently be desirable to occlude at
least the right common carotid artery with the balloon-tipped
cannula 10 and the left common carotid artery with a second
balloon-tipped cannula 12, as shown in FIG. 6B. Oxygenated medium
may then be perfused through either or both of the cannulas 10 and
12, preferably through both. Further optionally, cannulas 10, 12,
14, and 16 may be disposed within the lumens of the right common
carotid artery, left common carotid artery, right vertebral artery,
and left vertebral artery, respectively, as shown in FIG. 6C. Such
an arrangement is advantageous because it both reduces the risk of
entry of atheromatous material into the cerebral vasculature and
provides for multiple access points for introducing oxygenated
medium to the cerebral vasculature.
[0069] The arrangement of cannulas shown in FIG. 6C is not optimal
for at least two reasons. First, it requires the use of four
separate cannulas. Second, atheromatous material from the aortic
arch can enter both the right subclavian artery and the left
subclavian artery since the entry points to these arteries are not
occluded. Thus, an improved arrangement of multiple cannulas is
shown in FIG. 6D. There, a first balloon-tipped cannula 100 is
placed into the brachiocephalic artery and positioned to perfuse
oxygenated medium to the cerebral vasculature through both the
right common carotid artery and right vertebral artery. Loss of
oxygenated medium to the right arm may be inhibited by placing a
tourniquet 102 on the arm. A second balloon-tipped catheter 12 may
be placed in the left common carotid artery, generally as described
above. A third balloon-tipped catheter 104 is placed in the left
subclavian artery relatively near the branch point from the aortic
arch. Placement near the aortic arch branch will enhance the
isolation of the arterial system branching from the left subclavian
artery. Moreover, oxygenated medium perfused distally of the
balloon-tipped cannula 104 will flow upwardly through the left
vertebral artery into the left cerebral arterial vasculature. Loss
of such oxygenated medium may be inhibited by placing a second
tourniquet 106 on the patient's left arm.
[0070] As illustrated thus far, the balloon-tipped cannulas have
included only single balloons and have been introduced through the
vascular wall at a point immediately adjacent to the point of
occlusion. As discussed above, however, the cannulas need not be
introduced adjacent to the point of occlusion nor do they need to
be simple, single-balloon catheters. An alternative balloon-tipped
catheter arrangement employing a cannula 120 having a pair of a
balloons 122 and 124 as illustrated in FIG. 6E. The cannula 120 may
be introduced in a retrograde fashion through the right subclavian
artery, optionally from an artery of the arm, such as the axillary
artery or the brachial artery. The cannula 120 is advanced so that
the distal-most balloon 124 is disposed within the lumen of the
brachiocephalic artery. By inflating the balloon 124, blood flow
from the aortic arch to the vasculature above the brachiocephalic
artery is occluded. By inflating balloon 122, blood flow through
the right subclavian artery at points distal to the branch of the
right vertebral artery is also occluded. Perfusion ports 123 are
provided on the cannula 120 between the distal-most balloon 124 and
second balloon 122, and oxygenated medium may be introduced through
the perfusion ports to flow to both the right vertebral artery and
the right common carotid artery. Moreover, flow out the right
subclavian artery beyond balloon 122 is also occluded, helping to
direct substantially all flow of oxygenated medium to the cerebral
vasculature. Usually, the second balloon-tipped catheter 12 will be
disposed within the left common carotid artery and further
optionally (although not shown) one or more balloon-tipped
catheters may be used to occlude flow to the left vertebral artery,
as shown in either FIG. 6C or 6D.
[0071] When the oxygenated medium is autologous patient blood, it
will be necessary to collect at least a portion of the
oxygen-depleted blood after it has passed through the cerebral
vasculature and to return that blood to the patient after
filtering, reoxygenation, and optional cooling. The blood may be
collected in the venous vasculature which drains the brain,
typically by placing a pair of expansible occluders 20 and 22 into
the right internal jugular vein and left internal jugular vein,
respectively, as illustrated in FIG. 7. The expansible occluder 20
and 22 may be constructed similarly to the expansible occluders 10
and 12, but will include distal tips 24 and 26, respectively,
having a plurality of ports adapted to collect the oxygen depleted
blood as it flows toward the heart. As an alternative to blocking
the internal jugular veins with a pair of expansible occluders, the
superior vena cava may be blocked with a single expansible occluder
30, as illustrated in FIG. 8. In both cases, the blood or other
oxygen depleted medium collected in the venous side of the
vasculature will be returned to an extracorporeal system for
reoxygenation, pumping, and optional cooling, as will be described
in more detail in connection with FIG. 10 below: The expansible
occluders 20, 22, and 30, will be sized and adapted to be
surgically or percutaneously introduced to the associated vein.
[0072] In addition to isolation and perfusion of the cerebral
vasculature by any of the techniques described above, the present
invention also provides for optional perfusion of non-cerebral
portions of the patient vasculature, particularly the lower body
vasculature as illustrated in FIG. 9. Conveniently, the lower body
vasculature may be perfused by introducing blood or other
oxygenated medium into the descending aorta using an expansible
occluder 40, typically a balloon catheter, optionally a balloon
catheter adapted for introduction through the femoral artery in a
conventional manner. The expansible occluder 40 will include flow
ports, which are disposed below the balloon when a catheter is
placed within the thoracic aorta. This way, the oxygenated medium
will flow downwardly from the balloon into the lower arterial
vasculature. After perfusing through tissue in the lower body, the
oxygen depleted blood or other medium will flow into the venous
system and ultimately upwardly through the inferior vena cava. By
placing an expansible occluder 50 within the lumen of the inferior
vena cava may be occluded and the return blood flow collected. The
collected blood may then be circulated through an extracorporeal
recirculation system, as described in more detail in connection
with FIG. 10.
[0073] Referring now to FIG. 10, a patient P is undergoing an open
surgical procedure through a sternotomy S that exposes the aortic
arch AA and the superior vena cava SVC. Expansible occluders 10 and
12 are then placed into the right and left common carotid arteries,
respectively, and connected brachiocephalic to an extracorporeal
oxygenator and pump 70. Expansible occluder 30 (as illustrated in
FIG. 8) is introduced to the superior vena cava SVC and also
connected to the external oxygenator and pump 70. Blood is
introduced to the common carotid arteries through the expansible
occluders 10 and 12 and return to the external oxygenator and pump
through the expansible occluder 30. A reservoir of blood is
maintained within the external oxygenator and pump 70 so that
sufficient blood will remain in circulation even as a certain
amount of blood is lost since it flows outwardly to points other
than the superior vena cava.
[0074] Preferably, perfusion and oxygenation of the lower portion
of the patient P is accomplished using expansible occluders 40 and
50 which are introduced intravascularly according to conventional
techniques, such as the Seldinger technique. In this way, the
cerebral vasculature and lower body vasculature may be continuously
perfused with oxygenated blood while blood is kept out of the aorta
and the aorta may be opened for performing a desired procedure.
[0075] For open surgical procedures as illustrated in FIG. 10, the
patient's heart will be arrested using conventional techniques.
Typically, the heart will be catheterized and cooled, and supplied
with cardioplegia, according to known techniques. The aorta,
typically at the aortic arch, may then be opened and a desired
procedure performed. After the procedure is complete, cardioplegia
will be stopped--the heart will be warmed, and heart function
reestablished.
[0076] A particular advantage of the present invention is that the
cerebral vasculature may continue to be isolated during the period
immediately following cessation of bypass and reestablishment of
heart function. It will be appreciated that any procedure performed
in and around the aorta may leave significant debris in the aortic
lumen presenting a substantial risk of embolization to the patient.
By reestablishing heart function and blood flow through the aorta
while maintaining isolation of the cerebral vasculature, the
potentially embolic material may be cleared from the aorta and
removed to less sensitive portions of the vasculature. Blood flow
to the cerebral vasculature can then be reestablished, typically
from 2 minutes to 5 minutes following the restarting of the
heart.
[0077] Referring now to FIG. 11, kits according to the present
invention will comprise at least one expansible occluder 10,
usually comprising at least two expansible cannulas 10 and 12, as
illustrated, instructions for use (IFU) 75. The expansible
occluders 10 and 12 will be suitable for connection to an
extracorporeal flow system 70 (FIG. 10), or for connection to a
reservoir of oxygenated medium, depending on the intended use. The
instructions for use 75 will set forth any of the methods described
above. Usually, the expansible occluders 10 and 12 and instructions
for use 75 will be packaged together in a suitable package 80, such
as a pouch, tray, box, tube, or the like. Optionally, the
instructions for use may be printed in whole or in part on a
portion of the packaging 80. Usually, at least the expansible
occluders 10 and 12 will be sterilely maintained within the package
80. Other optional kit components which could be placed within the
package 80 include oxygenated medium, cerebral protective agents
and/or other drugs, additional catheters for connecting the
cannulas to system 70 or other extracorporeal apparatus,
replaceable cassettes for system 70 which permit replacement of all
system components which directly contact the blood, and the
like.
[0078] While the above is a complete description of the preferred
embodiments of the invention, various alternatives, modifications,
and equivalents may be used. Therefore, the above description
should not be taken as limiting the scope of the invention which is
defined by the appended claims.
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