U.S. patent application number 09/728996 was filed with the patent office on 2001-04-26 for cavo-atrial cannula and method of use.
Invention is credited to Cho, Peter.
Application Number | 20010000528 09/728996 |
Document ID | / |
Family ID | 23048818 |
Filed Date | 2001-04-26 |
United States Patent
Application |
20010000528 |
Kind Code |
A1 |
Cho, Peter |
April 26, 2001 |
Cavo-atrial cannula and method of use
Abstract
An improved method for performing cardiac surgery whereby one
uses cavo-atrial cannula to remove blood from the body while
performing cardiac surgery. The cavo-atrial cannula has at least
two sets of openings, a removable obturator, a curved tip, a closed
terminus, an open terminus, and a bend. The cavo-atrial cannula has
the first openings located adjacent to the curved tip and the
second openings on the side opposite the bend. The cavo-atrial
cannula contains various markings to indicate the correct
positioning of the cavo-atrial cannula. The cavo-atrial cannula is
inserted into the superior vena cava or inferior vena cava. The tip
of the cavo-atrial cannula can lie in either the right atrium or
the vena cava opposite from the insertion point, depending on the
type of surgery being performed.
Inventors: |
Cho, Peter; (Timonium,
MD) |
Correspondence
Address: |
David L. Marks
6110 Ivymount Road
Baltimore
MD
21209
US
|
Family ID: |
23048818 |
Appl. No.: |
09/728996 |
Filed: |
December 4, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09728996 |
Dec 4, 2000 |
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09274588 |
Mar 23, 1999 |
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6186981 |
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Current U.S.
Class: |
604/117 |
Current CPC
Class: |
A61M 25/0043 20130101;
A61M 1/3659 20140204; A61M 25/007 20130101 |
Class at
Publication: |
604/117 ;
604 |
International
Class: |
A61M 005/00 |
Claims
I claim:
1. An improved method of draining blood from a body during cardiac
surgery, said improvement comprising: making an incision in a vena
cava; inserting a cavo-atrial cannula into said incision in said
vena cava, wherein said cavo-atrial cannula has an open terminus, a
closed terminus, a bend, a first openings wherein said first
openings are located adjacent to said closed terminus, a second
openings wherein said second openings are located on the side of
said cannula opposite said bend, and a removable obturator capable
of occluding said second openings; positioning said cavo-atrial
cannula such that said closed terminus is located in the right
atrium; securing said cavo-atrial cannula to said vena cava;
withdrawing said removable obturator from said cavo-atrial cannula
through said open terminus; and attaching said cavo-atrial cannula
to tubing wherein said blood travels through said tubing to a
device for oxygenation and return to the body.
2. The method of claim 1 wherein said vena cava is the superior
vena cava.
3. The method of claim 1 wherein said vena cava is the inferior
vena cava.
4. An improved method of draining blood from a body during cardiac
surgery, said improvement comprising: making an incision in the
vena cava; inserting a cavo-atrial cannula into said incision in
said vena cava, wherein said cavo-atrial cannula has an open
terminus, a closed terminus, a bend, a first openings wherein said
first openings are located adjacent to said closed terminus, a
second openings wherein said second openings are located on the
side of said cannula opposite said bend, a third openings wherein
said third openings are located between said first openings and
said second openings, and a removable obturator capable of
occluding said second openings; positioning said cavo-atrial
cannula such that said closed terminus is located in the right
atrium; securing said cavo-atrial cannula to said vena cava;
withdrawing said removable obturator from said cavo-atrial cannula
through said open terminus; and attaching said cavo-atrial cannula
to tubing wherein blood travels through said tubing to a device for
oxygenation and return to the body.
5. The method of claim 4 wherein said vena cava is the superior
vena cava.
6. The method of claim 4 wherein said vena cava is the inferior
vena cava.
7. An improved method of draining blood from a body during cardiac
surgery, said improvement comprising: making an incision in the
superior vena cava; inserting a cavo-atrial cannula into said
incision in said vena cava, wherein said cavo-atrial cannula has an
open terminus, a closed terminus, a bend, a first openings wherein
said first openings are located adjacent to said closed terminus, a
second openings wherein said second openings are located on the
side of said cannula opposite said bend, and a removable obturator
capable of occluding said second openings; positioning said
cavo-atrial cannula such that said closed terminus is located in
the inferior vena cava; securing said cavo-atrial cannula to said
superior vena cava; withdrawing said removable obturator from said
cavo-atrial cannula through said open terminus; attaching said
cavo-atrial cannula to tubing wherein said blood travels through
said tubing to a device for oxygenation and return to the body; and
applying at least one tourniquet around said superior vena cava and
said inferior vena cava.
8. An improved method of draining blood from a body during cardiac
surgery, said improvement comprising: making an incision in the
inferior vena cava; inserting a cavo-atrial cannula into said
incision in said vena cava, wherein said cavo-atrial cannula has an
open terminus, a closed terminus, a bend, a first openings wherein
said first openings are located adjacent to said closed terminus, a
second openings wherein said second openings are located on the
side of said cannula opposite said bend, and a removable obturator
capable of occluding said second openings; positioning said
cavo-atrial cannula such that said closed terminus is located in
the superior vena cava; securing said cavo-atrial cannula to said
superior vena cava; withdrawing said removable obturator from said
cavo-atrial cannula through said open terminus; attaching said
cavo-atrial cannula to tubing wherein said blood travels through
said tubing to a device for oxygenation and return to the body; and
applying at least one tourniquet around said superior vena cava and
said inferior vena cava.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
1. This application is a Continuation in Part application related
to U.S. patent application Ser. No. 09/274,588 which has issued as
U.S. Pat. No. ______ on ______.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
2. None
REFERENCE TO MICROFICHE APPENDIX
3. N/A
BACKGROUND OF THE INVENTION
4. 1. Field of the Invention
5. This invention relates to the field of heart surgery. More
specifically, this invention relates to a method of performing
heart surgery using a cavo-atrial cannula to remove blood from the
body.
6. 2. Description of the Related Art
7. When the heart must be stopped for a surgical procedure, the
function of the heart and lungs is assumed temporarily by a
mechanical device, a pump oxygenator, which drains the patient's
blood, oxygenates it, and returns it to the patient through tubing
connected to cannulae placed in the patient's heart and aorta. This
surgical technique is known as cardiopulmonary bypass surgery.
Typically, drainage is accomplished by a single venous cannula,
possessing two sets of openings, placed through an incision in the
right atrium and secured in place by a pursestring-suture
tourniquet applied along the edges of the atrial incision such that
the cannula tip lies in the inferior vena cava. The set of openings
at the cannula's terminus drain blood from the inferior vena cava,
and the openings proximal to it drain the blood which has arrived
from the superior vena cava and other lesser sources into the right
atrium. An alternative method uses two venous cannulae, one
directed into the superior vena cava and the other into the
inferior vena cava. One or both of these cannulae are introduced
through incision(s) in the right atrium.
8. The currently used venous cannulae and the methods by which they
are placed in the heart present certain problems. The right atrium
suffers significant damage not only from the incisions made to
introduce the cannula(e) but also because of the right atrium's
relative inaccessibility to the protective measures used to
preserve heart tissue functional integrity during surgery. These
protective measures consist primarily of drugs, such as
cardioplegic solutions, infused into the blood supply of the heart
tissue to arrest beating, as well as the constant application of
ice-cold saline or ice to the surface of the arrested heart to slow
down the heart's metabolism. The method by which the cannula(e)
is/are currently placed in the right atrium prevents the protective
drugs from reaching the atrial tissue constrained in the
tourniquet. Furthermore, the atrial tissue at the entry site of the
cannula(e) escapes the cold saline bath inasmuch as the atrial
tissue is suspended upward out of the chest by the outward course
of the cannula(e) toward the pump oxygenator. The functional
consequences of direct injury to the atrial tissue as well as the
sub-optimal access to the protection afforded to the rest of the
heart include decreased strength of contraction and, perhaps more
importantly, disordered atrial rhythm, e.g., atrial fibrillation,
which can cause poor cardiac function, blood clots, and dangerously
high heart rates. The drugs used to treat atrial fibrillation also
have an array of potentially dangerous side-effects. The economic
costs of atrial dysfunction reflect the price of the drugs used to
treat it, longer hospital stays, and the additional hospital
admissions for related complications.
9. These problems can be avoided by making no incision in the
atrium, and instead, placing the venous drainage cannula through an
incision in the superior vena cava or inferior vena cava.
10. Currently available cannulae can not be inserted into the vena
cava as a single drainage conduit for blood from the venae cava and
right atrium for three reasons. First, most currently available
caval cannulae are designed to be used in pairs and if used singly
have too narrow a diameter for adequate venous drainage and to
maintain adequate flow of blood from the patient. Second, even if
the diameter of the currently available cannulae were enlarged
enough to maintain adequate flow of blood from the patient, the
placement of such enlarged diameter cannulae in the superior vena
cava would cause significant obstruction to blood flow from the
head and upper body which normally courses through the superior
vena cava into the right atrium. Similarly, enlarged diameter
cannulae can not be inserted into the inferior vena cava because
the placement of such cannulae in the inferior vena cava would
cause significant obstruction to blood flow from the lower body
which normally courses through the inferior vena cava into the
right atrium. Third, currently available cannulae contain
circumferential openings. If a large cannula with circumferential
openings lies obliquely just within the vena cava, then it would
increase the risk of entraining air into the pump circuit, causing
an "air lock" and obstruction to flow.
11. The placement of the openings in the currently available
cannulae is not appropriate for effective drainage of the blood
flowing down the superior vena cava when the cannulae are inserted
through the superior vena cava nor for effective drainage of the
blood flowing up the inferior vena cava when the cannulae are
inserted through the inferior vena cava. Use of currently available
cannulae for drainage of blood through the superior vena cava would
cause obstruction of the blood flow and could cause swelling of the
brain, neurological dysfunction, and stroke. Obstruction of
inferior vena cava blood flow could cause congestion and
dysfunction of the abdominal organs.
BRIEF SUMMARY OF THE INVENTION
12. This invention overcomes all of the problems associated with
the prior art. The heart may be effectively drained of blood during
cardiopulmonary bypass using a single cannula without injuring the
right atrium, thereby according the right atrium all the benefits
of cardioprotective measures. The device and the methods of its use
accomplish these effects by placing a cannula into the right atrial
cavity through an incision in the adjacent vena cava. No incision
is made in the atrium. There is no pursestring-suture tourniquet in
the atrial tissue. Cardioprotective agents are infused into all of
the atrial tissue. The atrium lies well within the chest,
accessible to the cold saline bath.
13. The present invention contains a bend in the cannula because a
cannula entering a vena cava from the usual opening in the
patient's chest must make a roughly right-angle bend to proceed on
to the right atrium or into the opposite vena cava.
14. The present invention also contains openings at a bend in the
cannula. These openings face the direction of approach of the blood
from the head and upper body if the invention is inserted into the
superior vena cava or from the lower body if the invention is
inserted into the inferior vena cava. Thus, the openings must be on
the outer aspect of the bend in the cannula. Furthermore, the
openings at the cannula's bend are not circumferential.
15. Therefore, in addition to openings at the closed terminus of
the cannula to drain the right atrium, the device incorporates
separate openings in the cannula, specifically positioned on the
outer aspect of the bend in the cannula such that it would receive
the blood from the head and upper body when inserted through the
superior vena cava into the right atrium and from the torso and
lower body when inserted through the inferior vena cava into the
right atrium.
16. Furthermore, in order to prevent the massive loss of blood
during insertion of the cannula into the vena cava in the form of
blood entering the openings at the closed terminus and exiting
through the openings at the bend before it is seated in the vena
cava, the device incorporates a removable obturator to block the
second openings from within the cannula until the cannula is
properly seated, at which time the obturator is withdrawn from the
lumen of the cannula.
17. In an alternative embodiment the removable obturator is placed
on the outside of the cannula over the openings at the bend. These
obturators can include a sliding cover over the openings that is
either moved or removed or a tape-like cover that is removed prior
to securing the cannula into position.
18. To maximize drainage of blood from the right atrium, the
diameter of the distal portion of the cannula should not be
substantially less than that of the cannula resting in the vena
cava. Therefore, the invention provides for little or no narrowing
of the cannula beyond the vena cava openings except a short curved
taper at the tip to facilitate initial insertion into the vena
cava.
19. The invention also pertains to an improvement in the method of
performing cardiopulmonary bypass surgery, the improvement being
the use of a cavo-atrial cannula inserted into the superior vena
cava or inferior vena cava and having its closed terminus within
the right atrium to remove blood from the patient. The cavo-atrial
cannula is connected to tubing through which the blood travels to a
pump oxygenator. From the pump oxygenator, the blood travels
through tubing to an arterial cannula positioned in the aorta or
another artery.
20. The invention also pertains to an improvement in the method of
performing cardiopulmonary bypass surgery, the improvement being
the insertion of a cavo-atrial cannula into either venae cava and
positioning the closed terminus of the cannula in the right atrium.
The cavo-atrial cannula has a curved tip at the closed terminus,
openings near the closed terminus, a bend, and openings at a bend
on the outside of the bend. In this improvement, if the cavo-atrial
cannula is inserted into the inferior vena cava, blood from the
lower body enters the lumen of the cannula via the openings at the
bend seated in the inferior vena cava while blood from the head,
upper body, and right atrium enters the lumen of the cannula via
the openings near the closed terminus, seated in the right atrium.
Alternatively, if the cavo-atrial cannula is inserted into the
superior vena cava, the blood from the head and upper body enters
the lumen of the cannula via the openings at the bend which is
seated in the superior vena cava while blood from the lower body
and right atrium enters the lumen of the cannula via the openings
near the closed terminus which is seated in the right atrium. In
this method, one removes the removal obturator from the openings at
the bend after insertion of the device into the venae cava to
prevent blood from flowing out of the device through the openings
at the bend. The cavo-atrial cannula is connected to tubing through
which blood travels to a pump oxygenator and any other device
before returning to the patient's body via arterial cannula placed
in aorta or other artery.
21. Another improvement for the method of cardiopulmonary bypass
surgery relates to using the cavo-atrial cannula having three sets
of openings. This cavo-atrial cannula is inserted into a vena cava,
the closed terminus is seated in the opposite vena cava. The
cavo-atrial cannula is secured into position and the obturator is
removed. Alternatively the obturator is removed or moved prior to
completely securing the cavo-atrial cannula into place. Blood from
the lower body enters the cannula via one set of openings. Blood
from the head and upper body enters the cannula via another set of
openings. Blood from the right atrium enters the cannula from a
third set of openings. The cannula is connected to tubing which
takes the blood to a pump oxygenator after which the blood is
returned to the body via a cannula previously placed in the aorta
or another artery.
22. This invention also relates to a method of removal of blood
from a patient so that one can perform surgery with an opened right
atrium. For this method of removal of blood from a patient during
surgery the cavo-atrial cannula is inserted in the superior vena
cava and then extended into the inferior vena cava or inserted into
the inferior vena cava and then extended into the superior vena
cava. The obturator is removed or moved prior to completely
securing the cannula into proper position, or completely removed
after securing the cannula into proper position. Again tubing is
connected to the cannula to take blood to a pump oxygenator after
which the blood is returned to the body via a cannula inserted into
the aorta or other artery. Tourniquets around the outside of the
vena cavae are used to prevent blood from entering into the right
atrium, thereby permitting one to perform surgery with the right
atrium open.
23. A further improvement to these methods is one using the safe
mark, the reference mark and the rotation mark to assist in the
proper positioning of the cannula in the patient's vena cava.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
24. FIG. 1 shows a side view of the invention according to the
preferred embodiment.
25. FIG. 2A shows a back view of the invention according to the
preferred embodiment.
26. FIG. 2B shows a front view of the invention according to the
preferred embodiment.
27. FIG. 3 shows a cut-away view of the invention according to the
preferred embodiment.
28. FIG. 4 shows a side view of an alternative embodiment of the
invention.
DETAILED DESCRIPTION OF THE INVENTION
29. FIG. 1 illustrates the preferred embodiment of a cavo-atrial
cannula, 10. A cavo-atrial cannula is a hollow tube containing an
upper portion, 11, a middle portion, 12, and a closed terminus, 14.
The closed terminus contains a curved tip, 13. At the end opposite
the curved tip is the cavo-atrial cannula's open terminus, 15. The
cavo-atrial cannula possesses, at a minimum, two sets of openings,
a first openings, 16, and a second openings, 17. The first openings
may be circumferential, but the second openings can not be
circumferential. In the preferred embodiment, the cavo-atrial
cannula also contains a bend, 18, located at the junction between
the upper portion and middle portion.
30. As illustrated in FIG. 3, when used in adult patients, it is
preferable for the interior diameter, 51, of the middle portion,
12, and upper portion, 11, to be constant until the beginning of
the closed terminus, 14. However, it is possible for the upper
portion, 11, to have a wider diameter above the safe mark, 30, than
the diameter in the middle portion, 12. The interior diameter, 51,
can range approximately between one to two centimeters which is
sufficient caliber to permit blood to flow freely within the lumen
of the cavo-atrial cannula, and to avoid sheer stress on the blood
cells. The thickness of the walls, 52, of the cavo-atrial cannula
does not add substantially to the overall diameter of the device.
The overall diameter of the cavo-atrial cannula enables the
invention to fit inside the patient's superior vena cava and/or
inferior vena cava. For pediatric patients, the interior diameter,
51, and overall diameter will be smaller than when used for adult
patients.
31. Referring to FIGS. 1, 2B, and 3, the curved tip, 13, has a
gradual taper. Thus, the cavo-atrial cannula's overall diameter
increases from the curved tip's terminus to the beginning of the
middle portion, 12. The curved tip is curved in the plane and same
direction as the bend, 18. The end of the curved tip terminates
prior to it reaching beyond the overall diameter of the cavo-atrial
cannula in order to minimize the tendency to snag tissue as the
cavo-atrial cannula is advanced or withdrawn. The curved tip makes
it easier for the user to insert the device into the patient's vena
cava. The tapered, curved tip also helps the surgeon to negotiate
the right angle of the vena cava with respect to the approach as he
first inserts the cannula into the vena cava.
32. The first openings, 16, can be located anywhere between the
closed terminus, 14, and a point in the middle portion located
approximately three centimeters from the junction of the middle
portion, 12, and the closed terminus. While the exact location can
vary, the first openings should be located at a point where the
interior diameter, 51, of the cavo-atrial cannula is large enough
to permit blood to flow freely within the lumen of the cavo-atrial
cannula, and to avoid sheer stress on the blood cells. When the
cavo-atrial cannula is properly inserted, the first openings should
be located inside the patient's right atrium. The first openings
will be of sufficient size to permit the unobstructed flow of blood
into the cannula and to minimize the disruption of red blood
cells.
33. In FIG. 1, the bend, 18, is located at the junction of the
middle portion, 12, and upper portion, 11. The angle of
inclination, 40, of the bend can range from approximately
twenty-five degrees (25.degree.) to one-hundred eighty degrees
(180.degree.), depending on the physical properties of material
used to make the cavo-atrial cannula. If the material is flexible
and can bend without creating a closure of the lumen of the device,
then the angle of inclination can be larger than one-hundred
thirty-five degrees (135.degree.). In the preferred embodiment, the
angle of inclination ranges between forty-five degrees (45.degree.)
and one-hundred thirty-five degrees (135.degree.).
34. In FIGS. 1 and 2A, the second openings, 17, of the cavo-atrial
cannula is located at the junction of the upper portion, 11, and
the middle portion, 12, on the outer side of the bend, 18. When the
cavo-atrial cannula is properly inserted into the vena cava, the
second openings is located so that blood from the vena cava can
flow into the cavo-atrial cannula. If the second openings was
absent the cavo-atrial cannula would obstruct the flow of blood
from the head to the heart when the invention is inserted into the
superior vena cava or from the lower body to the heart when the
invention is inserted into the inferior vena cava. The distance
from the curved tip, 13, to the second openings, 17, can range from
approximately five centimeters to approximately fifteen
centimeters.
35. The first openings, 16, and the second openings, 17, can be a
plurality of holes or slits adjacent to each other in the walls of
the cavo-atrial cannula. They may run laterally or longitudinally.
It is recommended that the walls of the cavo-atrial cannula
proximal to and surrounding the openings be of a stiffer, stronger
material than the rest of the walls of the cavo-atrial cannula for
increased support. The increased support is recommended but not
vital.
36. The distance between the first openings and the second openings
can range from approximately five to thirteen centimeters. The
length of the upper portion can be approximately twenty centimeters
or longer.
37. The cavo-atrial cannula, 10, can be made of any material that
is approved by the Food and Drug Administration for these types of
devices. The material should be flexible yet not able to bend or
kink so that the flow of blood will not be obstructed. Use of a
polyvinylchloride reinforced with an intramural spiral wire is
commendable.
38. In the preferred embodiment, as shown in FIGS. 1 and 3, the
cavo-atrial cannula has a removable obturator, 25, located inside
the lumen of the invention, extending from the second openings, 17,
through the open terminus, 15. The obturator occludes the second
openings while the cavo-atrial cannula is being inserted into the
patient. The obturator prevents blood which enters the lumen of the
cavo-atrial cannula via the first openings, 16, from leaving the
lumen of the invention through the second openings, 17, prior to
the proper seating of the cavo-atrial cannula within the vena cava.
Without the obturator, blood may exit the cavo-atrial cannula
inappropriately, causing excessive bleeding, blood loss, and
possibly death. The obturator, 25, may be made from plastic or any
other appropriate material. The obturator has an occluding portion,
26, and non-occluding portion, 27. The occluding portion covers the
second openings, 17, and extends above the second openings for some
distance. The diameter of the occluding portion is identical to or
slightly smaller than the interior diameter, 51, of the cavo-atrial
cannula so that the occluding section fits snugly inside the lumen
of the invention and prevents blood from entering or exiting the
cannula through the second openings, 17. The diameter of the
non-occluding portion, 27, of the obturator can be less than the
interior diameter, 51, of the cavo-atrial cannula so as to reduce
friction during withdrawal and insertion of the obturator, 25. When
properly seated, the obturator terminates at or just beyond the
bend, 18, and blocks completely the second openings, 17. The
obturator may be solid or hollow. After the cavo-atrial cannula is
properly inserted into the vena cava and is secured into place with
a Rummel tourniquet and pursestring suture, one slides the
obturator, 25, out through the open terminus, 15, thereby
uncovering the second openings, 17.
39. In alternative embodiments, the removable obturator can rest on
the outside of the cannula and cover the second openings. In one of
these embodiments, the obturator can be a strong, flexible
material, such as a bendable plastic or metal, that is detachably
secured by an adhesive to the outside of the device. It completely
covering the second openings. Alternatively, each hole or slit of
the second openings can be covered by an individual obturator. The
second openings are covered by the occluding portion, 26, of the
obturator. The non-occluding portion, 27, of the obturator extends
from the bottom edge of the occluding portion, closest to the
middle portion, 12. The non-occluding portion folds one-hundred
eighty degrees upon itself, traveling upward along the outside of
the occluding portion and the upper portion, 11, of the cannula.
After the cavo-atrial cannula is seated in a vena cava, but before
detachably securing it into place by tightening a Rummel tourniquet
and pursestring suture, one pulls the non-occluding portion upward,
peeling the occluding portion away from the second openings. The
adhesive must be strong enough to prevent the obturator from
falling off during handling but permits one to remove the obturator
by pulling on the non-occluding portion with a small amount of
force. Too strong of an adhesive may require too much force which
may cause the device to move around and injure the patient.
40. In a second alternative embodiment, the obturator is made of
stiff material. The occluding portion is shaped to conform to the
curvature of the outside of the cannula. The obturator presses
against the outside of the cannula and remains attached via
pressure of the occluding portion pressing against the cannula over
the second openings. A non-occluding portion extends upward from
the top of the occluding portion along the upper portion of the
cannula. After insertion of the device into a vena cava, one pulls
on the non-occluding portion to slide the occluding portion upward
along the outside of the cannula, thereby uncovering the second
openings. One can either remove the obturator completely or let it
stay attached to the cannula, so long as the obturator is
completely above the safe mark. Then one secures the cavo-atrial
cannula into place by tightening a Rummel tourniquet and
pursestring suture.
41. In any embodiment, after the occluding portion of the obturator
is moved away from the second openings, blood from the vena cava
enters the lumen of the cavo-atrial cannula through the second
openings. When the cavo-atrial cannula is used properly, the open
terminus, 15, remains outside the vena cava. After removal of the
obturator, 25, or uncovering of the second openings, depending on
the embodiment used, one connects the open terminus, 15, of the
cavo-atrial cannula to tubing that carries the blood to a pump
oxygenator or other equipment.
42. As shown in FIGS. 1, 2A and 2B, the cavo-atrial cannula has a
plurality of markings on the upper portion, 11. These markings are
visible markings. They can be colored lines or indentations or
bumps or a combination of all three on the exterior of the
cavo-atrial cannula. The markings need not be visible during
radiographic imaging of the device. The safe mark, 30, indicates
the lowest level at which one can safely tighten and secure a
pursestring suture. The safe mark is located approximately five
millimeters above the top of the second openings, 17, and
designates the point beyond which the cavo-atrial cannula should
not be withdrawn from the patient's vein because of the danger of
air entrainment. Air entrainment can occur if, after the
cavo-atrial cannula is connected to a pump oxygenator, air enters
the lumen of the cavo-atrial cannula through the second openings
and causes an air-lock. The safe mark ensures the proper depth of
insertion of the cavo-atrial cannula. The reference mark, 31, is
located approximately five millimeters above the safe mark. The
reference mark serves as a reference to warn that the last extent
of safe withdrawal of the cavo-atrial cannula during seating is
nearby. The safe mark and reference mark extend around the upper
portion, 11, perpendicular to the direction of flow of blood
through the cavo-atrial cannula.
43. In FIGS. 1 and 2B, the rotation mark, 32, runs on the exterior
of the cavo-atrial cannula, on the side containing the angle of
inclination, 40, and opposite the location of the second openings,
17. It begins on the middle portion, 12, and terminates on the
upper portion, 11, above the safe mark, 30. The rotation mark, 32,
assists in identifying the axial rotation of the second openings,
17, particularly in those embodiments of the invention with a angle
of inclination greater than 90.degree..
44. FIG. 3 illustrates the relative placement of the cavo-atrial
cannula when inserted into a vena cava, 55, and advanced into the
right atrium, 56. The pursestring suture and Rummel tourniquet are
placed at the safe mark, 30, or higher than the safe mark (see FIG.
1).
45. As illustrated in FIG. 4, in another alternative embodiment,
the cavo-atrial cannula has three sets of openings. This
alternative embodiment differs from the preferred embodiment by
having an extended middle portion, 12a, and another set of
openings, the third openings, 35. The third openings, 35, is
located in or just prior to the beginning of the curved tip, 13.
The extended middle portion allows the curved tip, 13, and third
openings, 35, to lie in the vena cava opposite the site of
insertion. The third openings, 35, when the cavo-atrial cannula is
properly inserted into the superior vena cava, is located in the
inferior vena cava, and thus can drain blood from the inferior vena
cava. The extended middle portion, 12a, is extended approximately
eight centimeters in length. In this alternative embodiment, the
first openings, 16, and the second openings, 17, are located in the
same positions with respect to each other on the cavo-atrial
cannula as in the embodiment containing two sets of openings.
46. The improved methods of cardiopulmonary bypass surgery using
the cavo-atrial cannula differs from current surgical techniques.
In current surgical techniques, one either maks an incision in the
right atrium and inserts a cannula through the right atrium into
the inferior vena cava, or make two incisions for separate
cannulation of each vena cava. In the improved method of
cardiopulmonary bypass surgery of this invention, one makes an
incision in the superior vena cava and inserts the cavo-atrial
cannula into the superior vena cava. One then advances the
cavo-atrial cannula through the superior vena cava to the right
atrium. (See FIG. 3) The curved tip should either rest within the
right atrium if one uses the cavo-atrial cannula with a first
openings and a second openings or the inferior vena cava if one
uses the cavo-atrial cannula with a first openings, a second
openings, and a third openings. Alternatively, one makes an
incision in the inferior vena cava and inserts the cavo-atrial
cannula into the inferior vena cava. One then advances the
cavo-atrial cannula through the inferior vena cava to the right
atrium. (See FIG. 3) The curved tip should either rest within the
right atrium if one uses the cavo-atrial cannula with a first
openings and a second openings or the superior vena cava if one
uses the cavo-atrial cannula with a first openings, a second
openings, and a third openings. Caution must be exercised when the
cavo-atrial cannula is inserted into the inferior vena cava because
the extent of the inferior vena cava in the chest is quite
short.
47. In these improved methods of cardiopulmonary bypass surgery,
there are several steps that are performed on the patient prior to
the commencement of surgery; these steps are well-known in the art
field of surgery and, more specifically, cardiac surgery. After
performing these well-known steps, the patient is lying on the
operating table, anaesthetized, and has intravenous lines inserted
into the patient's body. Various apparatuses are attached to the
patient to monitor the patient's physiological status.
48. To begin cardiopulmonary bypass surgery, one exposes the heart
through a sternotomy incision. Heparin or other anticoagulant drug
is administered intravenously to prevent clotting of the patient's
blood. Next one makes an incision in the aorta or other artery and
inserts an arterial cannula into the artery. One applies a
tourniquet around the arterial opening and the arterial cannula to
keep the arterial cannula in place and prevent leakage of blood out
and entrainment of air into the artery. One attaches tubing to the
arterial cannula; the tubing is connected to the pump oxygenator
and other various equipment.
49. In the improved method of cardiopulmonary bypass surgery, one
makes an incision in the superior vena cava and inserts the curved
tip of the cavo-atrial cannula into the superior vena cava. Then
one inserts the middle portion of the cavo-atrial cannula into the
superior vena cava such that the curved tip comes to rest in the
right atrium, if the cavo-atrial cannula has two sets of openings,
or the inferior vena cava, if the cavo-atrial cannula has three
sets of openings. One positions the cavo-atrial cannula such that
the second openings, 17, is located inside the patient's superior
vena cava and pointed toward the patient's head so that the blood
from the head and upper body can enter into the lumen of the
cavo-atrial cannula after removal of the obturator from the second
openings. Blood in the right atrium and the inferior vena cava can
enter the lumen of the cavo-atrial cannula through the first
openings or the first openings and third openings, depending on the
version of the cavo-atrial cannula used.
50. In an alternative improved method of cardiopulmonary bypass
surgery, one makes an incision in the patient's inferior vena cava,
and inserts the curved tip of the cavo-atrial cannula into the
inferior vena cava. Then one inserts the middle portion of the
cavo-atrial cannula into the inferior vena cava such that the
curved tip comes to rest in the right atrium, if the cavo-atrial
cannula has two sets of openings, or the superior vena cava, if the
cavo-atrial cannula has three sets of openings. One positions the
cavo-atrial cannula such that the second openings, 17, is located
inside the patient's inferior vena cava and pointed toward the
patient's feet so that the blood from the lower body can enter into
the lumen of the cavo-atrial cannula after removal of the obturator
from the second openings. Blood in the right atrium and the
superior vena cava can enter the lumen of the cavo-atrial cannula
through the first openings or the first openings and third
openings, depending on the version of the cavo-atrial cannula
used.
51. During insertion and positioning of the cavo-atrial cannula,
one uses the safe mark, 30, and reference mark, 31, on the upper
portion, 11, to make sure that the cavo-atrial cannula is inserted
to the proper depth. Also, one uses the rotation mark, 32, to make
sure that the cavo-atrial cannula is in the proper orientation.
52. Depending of which embodiment of the obturator that one uses,
the steps are different but accomplish the same goal.
53. If one uses the obturator that covers the second openings from
the lumen of the cavo-atrial cannula, first one detachably secures
the cavo-atrial cannula using a variety of methods known in the
field. A preferred method is to use a Rummel tourniquet with a
pursestring suture to detachable secure the cavo-atrial cannula to
the superior vena cava or inferior vena cava. Then, after the
cavo-atrial cannula is inserted into the patient's vena cava and
properly secured, one removes the obturator, 25, by withdrawing the
obturator through the open terminus, 15. After removal of the
obturator, one connects tubing to the open terminus of the
cavo-atrial cannula.
54. If one uses the obturator that covers the second openings from
the outside of the cavo-atrial cannula, one loosely detachably
secures the cavo-atrial cannula into place using a variety of
methods known in the field with the preferable method being a
Rummel tourniquet and pursestring suture. Then one uncovers the
second openings by removing or moving the obturator. Next, one
tightly detachably secures the cavo-atrial cannula into proper
position. Then one attaches tubing to the open terminus of the
cavo-atrial cannula.
55. The Rummel tourniquet or other type of securing mechanism is to
prevent blood from leaking out of the incision in the venae cavae
and to prevent air from entraining into the venae cavae and
becoming entrapped inside the cavo-atrial cannula.
56. The tubing attached to the open terminus carries blood to a
pump oxygenator or any other device. Gravity drainage is the
preferable mode of removal of blood from the body, however, one can
also use augmented suction drainage. Other instruments to which the
cavo-atrial cannula can be attached may utilize other methods for
the draining of blood. Blood is returned from the pump oxygenator
to the patient's body via tubing and the arterial cannula inserted
into the aorta or other artery.
57. While using the cavo-atrial cannula, cardioplegic solutions is
infused into the heart's blood supply to arrest the heart and/or
ice-cold saline is applied topically to the heart, if the surgeon
so chooses. Also, blood passing through the pump oxygenator may be
cooled. One blocks entry of blood and/or cardioplegic solution into
the coronary blood vessels on which one is operating using
well-known in the art-field techniques.
58. After one completes the surgical tasks that required the
diversion of the patient's blood away from the heart, one first
restores cardiac function by flushing out the cardioplegic
solutions from the coronary vessels and restores blood flow to the
coronary blood vessels. Next one removes the tourniquets from the
vena cava. Once the temperature of the patient is normal, one weans
the heart from the cardiopulmonary bypass equipment, such as the
pump oxygenator and/or other equipment, by progressively decreasing
the pump flow rates. Then one removes the cavo-atrial cannula from
the vena cava and sutures close the cannulation hole in the vena
cava. One also removes the arterial cannula and sutures close the
hole in the artery or aorta. Reversal of the effects of the
anticoagulation drugs is accomplished by administering protamine or
a similar acting drug. Then one places temporary pacing wires on
the heart to help control the heart's rhythm and inserts temporary
drains to remove any fluid accumulation around the heart. Finally
one closes the chest. Other post-operative care is provided to the
patient which is well-known in the art field of surgery and more
specifically cardiac surgery.
59. When one desires to perform surgery with the patient's right
atrium opened, such as during mitral valve surgery, one must divert
the patient's blood from the body to a pump oxygenator prior to the
entry of blood into the right atrium, and then return the blood to
the patient's body via an artery or aorta. In such a manner, one
can prevent blood from interfering with the surgery and prevent
massive air locks in the venous drainage tubing. For this type of
surgery through an atrium, one can use the cavo-atrial cannula to
remove blood from the patient's body. In this method, the
cavo-atrial cannula would be approximately fifteen centimeters from
the curved tip to the second openings. One would use a cavo-atrial
cannula with only the first openings and the second openings.
60. In this method, there are several steps that are performed on
the patient prior to the commencement of surgery; these steps are
well-known in the art field of surgery and more specifically
cardiac surgery. After performing all of these well-known steps,
the patient is lying on the operating table, anaesthetized, and has
intravenous lines inserted into the patient's body. Various
apparatuses are attached to the patient to monitor the patient's
physiological status.
61. To begin the cardiac surgery, one exposes the heart through a
sternotomy incision. Heparin or other anticoagulant drug is
administered intravenously to prevent clotting of the patient's
blood. Next one makes an incision in the aorta or other artery and
inserts an arterial cannula into the artery. One applies a
tourniquet around the arterial opening and the arterial cannula to
keep the arterial cannula in place and prevent leakage of blood out
and entrainment of air into the artery. One attaches tubing to the
arterial cannula; the tubing is connected to the pump oxygenator
and other various equipment.
62. In the improved method of cardiac surgery, one makes an
incision in the superior vena cava and inserts the curved tip of
the cavo-atrial cannula into the superior vena cava. Then, one
inserts the middle portion of the cavo-atrial cannula into the
superior vena cava such that the curved tip comes to rest in the
inferior vena cava. One positions the cavo-atrial cannula such that
the second openings face toward the patient's head so that all the
blood flowing down the superior vena cava from the head and upper
body can enter into the lumen of the cavo-atrial cannula upon
uncovering of the second openings and be diverted away from the
heart. The blood from the lower body enters the cavo-atrial cannula
from the inferior vena cava through the first openings and is
diverted away from the heart.
63. In an alternative improved method of cardiac surgery, after the
arterial tubing is connected to the arterial cannula and pump
oxygenator, one makes an incision in the inferior vena cava and
inserts the curved tip of the cavo-atrial cannula into the inferior
vena cava. Then, one inserts the middle portion of the cavo-atrial
cannula into the inferior vena cava such that the curved tip comes
to rest in the superior vena cava. One positions the cavo-atrial
cannula such that the second openings face toward the patient's
legs so that all the blood flowing up the inferior vena cava from
the lower body can enter into the cavo-atrial cannula upon
uncovering of the second openings and be diverted away from the
heart. The blood from the head and upper body enters the
cavo-atrial cannula from the superior vena cava through the first
openings and is diverted away from the heart.
64. During insertion and positioning of the cavo-atrial cannula,
one uses the safe mark, 30, and reference mark, 31, on the upper
portion, 11, to make sure that the cavo-atrial cannula is inserted
to the proper depth. Also, one uses the rotation mark, 32, to make
sure that the cavo-atrial cannula is in the proper orientation.
65. Depending of which embodiment of the obturator that one uses,
the steps are different but accomplish the same goal.
66. If one uses the obturator that covers the second openings from
the lumen of the cavo-atrial cannula, first one detachably secures
the cavo-atrial cannula using a variety of methods known in the
field. A preferred method is to use a Rummel tourniquet with a
pursestring suture to detachable secure the cavo-atrial cannula to
the superior vena cava or inferior vena cava. Then, after the
cavo-atrial cannula is inserted into the patient's vena cava and
properly secured, one removes the obturator, 25, by withdrawing the
obturator through the open terminus, 15. After removal of the
obturator, one connects tubing to the open terminus of the
cavo-atrial cannula.
67. If one uses the obturator that covers the second openings from
the outside of the cavo-atrial cannula, one loosely detachably
secures the cavo-atrial cannula into place using a variety of
methods known in the field with the preferable method being a
Rummel tourniquet and pursestring suture. Then one uncovers the
second openings by removing or moving the obturator. Next, one
tightly detachably secures the cavo-atrial cannula into proper
position. Then one attaches tubing to the open terminus of the
cavo-atrial cannula.
68. The Rummel tourniquet or other type of securing mechanism is to
prevent blood from leaking out of the incision in the venae cavae
and to prevent air from entraining into the venae cavae and
becoming entrapped inside the cavo-atrial cannula.
69. The tubing attached to the open terminus carries blood to a
pump oxygenator or any other device. Gravity drainage is the
preferable mode of removal of blood from the body, however, one can
also use augmented suction drainage. Other instruments to which the
cavo-atrial cannula can be attached may utilize other methods for
the draining of blood. Blood is returned from the pump oxygenator
to the patient's body via tubing and the arterial cannula inserted
into the aorta or other artery.
70. Next one applies a tourniquet around the superior vena cava
near the junction of the superior vena cava and the right atrium,
and around the inferior vena cava near the junction of the inferior
vena cava and the right atrium using well-known in the art-field
techniques. In such a manner, one prevents the flow of blood into
the right atrium and, upon opening of the right atrium, air from
entering into the venae cavae. Furthermore, the tourniquets prevent
air from entering into the cavo-atrial cannula and becoming
entrapped. After securing the tourniquets around the superior vena
cava and the inferior vena cava, one arrests the heart by perfusing
the coronary vessels with cardioplegic solutions. Topical ice-cold
saline or ice may be applied to the heart surface. The patient may
be cooled by cooling the blood passing through the pump oxygenator.
Next, one makes an incision into the right atrium. One can proceed
with the surgery on the mitral valve or other section of the
heart.
71. After one has completed the surgical tasks that required the
diversion of the patient's blood away from the heart, one first
restores cardiac function by flushing out the cardioplegic
solutions from the coronary vessels and restores blood flow to the
coronary blood vessels. Next one removes the tourniquets from the
venae cavae. Once the temperature of the patient is normal, one
weans the heart from the cardiopulmonary bypass equipment, such as
the pump oxygenator and/or other equipment, by progressively
decreasing the pump flow rates. Then one removes the cavo-atrial
cannula from the vena cava and sutures close the cannulation hole
in the vena cava. One also removes the arterial cannula and sutures
close the hole in the artery or aorta. Reversal of the effects of
the anticoagulation drugs is accomplished by administering
protamine or a similar acting drug. Then one places temporary
pacing wires on the heart to help control the heart's rhythm and
inserts temporary drains to remove any fluid accumulation around
the heart. Finally one closes the chest. Other post-operative care
is provided to the patient which is well-known in the art field of
surgery and more specifically cardiac surgery.
72. Although the present invention has been described and
illustrated in detail, it is clearly understood that the same is by
way of illustration and example and is not to be taken by way of
limitation, the spirit and scope of the present invention being
limited only by terms of the appended claims.
* * * * *