U.S. patent application number 12/860106 was filed with the patent office on 2011-05-12 for bifurcated outflow cannulae.
This patent application is currently assigned to CIRCULITE, INC.. Invention is credited to John P. Budris, Robert C. Farnan.
Application Number | 20110112353 12/860106 |
Document ID | / |
Family ID | 43970223 |
Filed Date | 2011-05-12 |
United States Patent
Application |
20110112353 |
Kind Code |
A1 |
Farnan; Robert C. ; et
al. |
May 12, 2011 |
BIFURCATED OUTFLOW CANNULAE
Abstract
A bifurcated cannula for directing blood into the arterial
system. The bifurcated cannula including an ingress channel and
first and second egress channels. The first egress channel directs
a first portion of the blood entering the bifurcated cannula into
the arterial system in a first direction. The second egress channel
directs a second portion of the blood entering the bifurcated
cannula into the arterial system in a direction that opposes the
first direction.
Inventors: |
Farnan; Robert C.;
(Rivervale, NJ) ; Budris; John P.; (Cheshire,
CT) |
Assignee: |
CIRCULITE, INC.
Saddle Brook
NJ
|
Family ID: |
43970223 |
Appl. No.: |
12/860106 |
Filed: |
August 20, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61259347 |
Nov 9, 2009 |
|
|
|
Current U.S.
Class: |
600/16 |
Current CPC
Class: |
A61M 60/857 20210101;
A61M 60/00 20210101; A61M 60/148 20210101; A61M 60/205 20210101;
A61M 60/122 20210101 |
Class at
Publication: |
600/16 |
International
Class: |
A61M 1/12 20060101
A61M001/12 |
Claims
1. A bifurcated cannula for directing blood into the arterial
system having blood flowing in a first direction, the bifurcated
cannula comprising: an ingress channel for receiving blood flow
from a pump; a first egress channel configured to direct a first
portion of the blood from the ingress channel into the arterial
system in the first direction; and a second egress channel
configured to direct a second portion of the blood from the ingress
channel into the arterial system in a direction that opposes the
first direction.
2. The bifurcated cannula of claim 1, wherein a cross-sectional
area of each of the first and second egress channels determines the
first and second portions of blood flowing through the first and
second egress channels.
3. The bifurcated cannula of claim 2, wherein cross-sectional areas
of the first and second egress channels are sized such that the
first portion of the blood is less than the second portion of the
blood.
4. The bifurcated cannula of claim 2, wherein cross-sectional areas
of the first and second egress channels are sized such that the
first and second portions of the blood are each 50% of the blood
flowing through the ingress channel.
5. The bifurcated cannula of claim 1, wherein first and second
stent grafts are coupled in fluid communication respectively with
the first and second egress channels and further adapted to be
connected to the arterial system.
6. The bifurcated cannula of claim 5, wherein an outer surface of
each of the first and second egress channels includes barbs for
retaining the respective stent grafts.
7. The bifurcated cannula of claim 1, wherein an extension tube is
coupled in fluidic communication with the ingress channel and
further adapted to be connected to the pump.
8. The bifurcated cannula of claim 1, further comprising a flow
selector configured to reduce a cross-sectional area of either of
the first or second egress channels.
9. The bifurcated cannula of claim 8, wherein the flow selector is
an iris having two or more pivotable blades.
10. The bifurcated cannula of claim 1 further comprising: a first
channel fitting received by the first egress channel, wherein a
cross-sectional area of a lumen through the first channel fitting
is smaller than a cross-sectional area of the first egress
channel.
11. The bifurcated cannula of claim 10, further comprising: a
second channel fitting received by the second egress channel,
wherein a cross-sectional area of a lumen through the second
channel fitting is smaller than a cross-sectional area of the
second egress channel.
12. A method of removing the bifurcated cannula of claim 1, wherein
first and second stent grafts couple the first and second egress
channels to the arterial system, the method comprising: disengaging
the pump from the ingress channel; removing the pump; removing the
bifurcated cannula; and fluidicly coupling the first and second
stent grafts such that the blood flowing in the first direction
enters the second stent graft and flows into the first stent graft
in the first direction and then flows back into the arterial system
in the first direction.
13. A method of directing blood from a pump to the arterial system
having blood flowing in a first direction with a bifurcated cannula
comprising an ingress channel and first and second egress channels,
the method comprising: directing the blood from the pump into the
ingress channel of the bifurcated cannula; directing a first
portion of the blood through the first egress channel and into the
arterial system such that the first portion enters the arterial
system in the first direction; and directing a second portion of
the blood entering the bifurcated cannula from the ingress channel
through the second egress channel and into the arterial system such
that the second portion of the blood enters the arterial system in
a direction that opposes the first direction.
14. The method according to claim 13, wherein directing the first
and second portions is determined by relative cross-sectional areas
of each of the first and second egress channels.
15. The method according to claim 13, wherein the directing of the
first and second portions is determined by a flow selector, wherein
the flow selector is configured to reduce a cross-sectional area of
either of the first or second egress channels.
16. The method according to claim 13, further comprising: coupling
the first and second egress channels in fluidic communication
respectively to the arterial system by first and second stent
grafts.
17. A method of disengaging a circulatory assist system from the
arterial system of a patient having blood flowing in a first
direction, wherein the circulatory assist system includes a
flexible cannula body coupling the left side of the heart of a
patient to a pump and a bifurcated cannula comprising an ingress
channel for receiving blood from the pump, a first egress channel
configured to direct a first portion of the blood from the ingress
channel into a first stent graft coupled to the arterial system
such that the blood moves in the first direction, and a second
egress channel configured to direct a second portion of the blood
from the ingress channel into a second stent graft coupled to the
arterial system such that the blood moves in a direction that
opposes the first direction, the method comprising: disengaging the
first and second egress channels from the first and second stent
grafts; and fluidicly coupling the first and second stent grafts
such that the blood flowing in the first direction enters the
second stent graft and flows into the first stent graft in the
first direction and then flows back into the arterial system in the
first direction.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the priority of U.S. Provisional
Patent Application Ser. No. 61/259,347, filed on Nov. 9, 2009
(pending), the disclosure of which is incorporated by reference
herein.
TECHNICAL FIELD
[0002] The present invention relates generally to devices for
assisting the heart in moving blood through the body; more
specifically the invention relates to pump outflow cannulae.
BACKGROUND
[0003] The circulatory system of the human body transports blood
containing chemicals, such as metabolites, hormones, and cellular
waste products, to and from the cells. This organ system includes
the heart, blood, and a vascular network. Veins are vessels that
carry blood toward the heart while arteries carry blood away from
the heart. The human heart consists of two atrial chambers and two
ventricular chambers. Atrial chambers receive blood from the veins
and the ventricular chambers, which include larger muscular walls,
pump blood from the heart. Movement of the blood is as follows:
blood enters the right atrium from either the superior or inferior
vena cava and moves into the right ventricle. From the right
ventricle, blood is pumped to the lungs via pulmonary arteries to
become oxygenated. Once the blood has been oxygenated, the blood
returns to the heart by entering the left atrium, via the pulmonary
veins, and flows into the left ventricle. Finally, the blood is
pumped from the left ventricle into the aorta and the vascular
network.
[0004] In some instances, it becomes necessary to maintain fluidic
communication with the vascular network. For example, a circulatory
assist system uses a pump to aid in moving blood through the
vascular network, thereby relieving the symptoms associated with
congestive heart failure (commonly referred to as heart disease).
The pump of the circulatory assist system includes inflow and
outflow cannulae. Often the inflow cannula connects the left side
of the heart to the pump; the outflow cannula connects the pump to
the arterial network.
[0005] However, the fluidic output of the pump will often greatly
exceed the natural fluid capacity of the particular artery used for
implanting the outflow cannula. The insufficiency of the venous
network to then immediately compensate for the increased blood
inflow may result in edema of the extremity immediate to the
implanted outflow cannula. While the venous network may adapt and
compensate over time, it would be beneficial to have devices that
better distribute the fluid flow from the pump in a manner that
would prevent the initial occurrence of swelling.
SUMMARY
[0006] In one illustrative embodiment, the present invention is
directed to a bifurcated cannula for directing blood into the
arterial system. The bifurcated cannula including an ingress
channel and first and second egress channels. Blood from a pump
flows into the bifurcated cannula through the ingress channel. The
first egress channel directs a first portion of the blood entering
the bifurcated cannula into the arterial system in a first
direction. The second egress channel directs a second portion of
the blood entering the bifurcated cannula into the arterial system
in a direction that opposes the first direction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a diagrammatic view of a circulatory assist system
with the outflow of the pump being connected to the right
subclavian artery by a bifurcated cannula, with the heart shown in
cross-section.
[0008] FIG. 2 is a perspective view of one exemplary embodiment of
a bifurcated outflow cannula connected to the right subclavian
artery and an implantable pump.
[0009] FIG. 3 is a cross-sectional view of the bifurcated outflow
cannula shown in FIG. 2.
[0010] FIG. 4 is a perspective view of an exemplary method of
removing the bifurcated outflow cannula and connecting the stent
grafts.
[0011] FIG. 5A is a cross-sectional view of another embodiment of a
bifurcated outflow cannula with a channel fitting.
[0012] FIG. 5B is a view similar to FIG. 5A, but showing the
channel fitting assembled with the bifurcated outflow cannula.
[0013] FIGS. 6-8 are cross-sectional views of additional
embodiments of the bifurcated outflow cannulae.
[0014] FIG. 9 is a diagrammatic view of an alternate method of
implanting the circulatory assist system, with the heart shown in
cross-section.
DETAILED DESCRIPTION
[0015] FIG. 1 illustrates an implanted circulatory assist system
10. For illustrative purposes, certain anatomy is shown including
the heart 12 of a patient 14 having a right atrium 16, a left
atrium 18, a right ventricle 20, and a left ventricle 22. Blood
from the left and right subclavian veins 24, 26 and the left and
right jugular veins 28, 30 enters the right atrium 16 through the
superior vena cava 32 while blood from the lower parts of the body
enters the right atrium 16 through the inferior vena cava 34. The
blood is pumped from the right atrium 16, to the right ventricle
20, and to the lungs (not shown) to be oxygenated. Blood returning
from the lungs enters the left atrium 18 via pulmonary veins 36 and
is then pumped into the left ventricle 22. Blood leaving the left
ventricle 22 enters the aorta 38 and flows into the left subclavian
artery 40, the left common carotid 42, and the brachiocephalic
trunk 44 including the right subclavian artery 46 and the right
common carotid 48.
[0016] With respect to the implanted circulatory assist system 10,
a flexible cannula body 50 extends from within the left atrium 18,
through the intra-atrial septum 52, and percutaneously to a
vascular access site 54 in the right subclavian vein 26. The
flexible cannula body 50 is attached to an input port 56 of an
implantable pump 58. Though not shown, the flexible cannula body 50
may alternatively be surgically implanted into the heart 12 and
extend to the pump 58 through the thoracic cavity.
[0017] The pump 58 may be an axially-driven pump with an impeller
(not shown). Those skilled in this art, however, recognize that
other types of pumps may be used in other embodiments but may
include pumps such as those described in U.S. application Ser. No.
11/627,444, published as 2007/0197854, which is incorporated herein
by reference in its entirety. The suitable pump 58 for use with the
circulatory assist system 10 may be capable of pumping blood.
[0018] A cable 60 can extend transdermally from the pump 58 to a
position in the abdomen where the cable 60 exits the patient 14 and
may connect to a power supply (not shown). Suitable power supplies
may be any universal-type power supply that sends power to the pump
58 via the cable 60 and may include, but is not limited to, a
rechargeable battery pack.
[0019] The physician may position the implantable pump 58 at least
subcutaneously and, optionally, submuscularly in a pump pocket 62
located near the vascular access site 54, or alternatively,
maintain the pump 58 externally.
[0020] A bifurcated outflow cannula 64 connects an output port 66
of the implantable pump 58 to a suitable artery, illustrate here as
the right subclavian artery 46. One skilled in the art would
understand that while the bifurcated outflow cannula 64 is
illustrated as extending over the right subclavian vein 26 to the
right subclavian artery, in practice the bifurcated outflow cannula
64 would likely reside beneath the right subclavian vein 26.
[0021] FIGS. 2 and 3 illustrate the bifurcated outflow cannula 64
formed as a y-connector having an ingress channel 68 and first and
second egress channels 70, 72. The first egress channel 70, as
illustrated, directs blood into the right subclavian artery 46 via
a first stent graft 74 and in a direction that opposes (i.e.,
retrograde) the native blood flow direction of the right artery 46,
illustrated by arrow 75. The second egress channel 72, as
illustrated, directs blood into the artery 46 via a second stent
graft 76 and in a direction that is the same (i.e., radial) as the
native blood flow direction of the right subclavian artery 46. The
stent grafts 74, 76 may be any commercially-available self
expanding, covered, endovascular stent graft, such as the FLAIR,
which is manufactured by Bard Peripheral Vascular (Tempe, Ariz.) or
the covered WALLSTENT by Boston Scientific (Natick, Mass.). As
illustrated, the size of the stent grafts 74, 76 are selected to
allow for a minimum of about 5 cm engagement within the vascular
structure and up to about 10 cm of length outside of the vascular
structure for connection to the bifurcated outflow cannula 64;
however, the size and lengths of the stent grafts 74, 76 should not
be limited to those specifically shown.
[0022] FIG. 3 illustrates the further details of the bifurcated
outflow cannula 64 in cross-section. The bifurcated outflow cannula
64 may be machined from a metallic material, for example titanium,
and polished to minimize the incidence of thrombus formation;
alternatively, the bifurcated outflow cannula 64 may be molded from
a polymeric material, such as silicone or urethane.
[0023] The egress channels 70, 72 are constructed to permit a
desired, relative amount of blood flow in the radial and retrograde
directions. As shown, the second egress channel 72 branches distal
to the first egress channel 70; however, other arrangements may be
used. The egress channels 70, 72 are constructed with lumens 78, 80
having relative cross-sectional areas that are selected to provide
a retrograde:radial flow ratio that is approximately 80:20 to meter
the blood flow from the pump 58. Accordingly, a first flow through
the first egress channel 70 in the retrograde direction will be
high volume while a second flow through the second egress channel
72 in the radial direction will be low volume. Though not
specifically shown, it is possible to construct the cross-sectional
areas such that the ratios are 50:50 or other ratios as desired,
but generally the volume directed in the retrograde direction will
meet or exceed the volume directed in the radial direction.
[0024] Referring now to FIGS. 1, 2, and 3, in use, the physician
creates first and second vascular incisions 82, 84 in the
appropriate vascular structure, illustrated here as the right
subclavian artery 46. The first and second stent grafts 74, 76 are
directed into and deployed in the right subclavian artery 46 in a
manner that is well known to one that is skilled in the art and
that accommodates placement of the bifurcated outflow cannula
64.
[0025] The physician then positions the proximal ends of the stent
grafts 74, 76 over an outer surface of the respective egress
channels 70, 72 of the bifurcated outflow cannula 64. The outer
surface may be constructed to include one or more barbs 86, 88 for
providing resistance against the undesired removal of the stent
grafts 74, 76. Graft collets 90, 92 may then be used to clamp and
secure the stent grafts 74, 76 onto the egress channels 70, 72 in a
manner that is known.
[0026] If desired, the physician may connect an extension tube 94
between the ingress channel 68 and the outflow port 66 of the pump
58. In this way, the pump 58 may be positioned at a desired
distance from the right subclavian artery 46. The extension tube 94
may be constructed from a biodurable, low durometer thermoplastic
or thermoset elastomer material. Coupling of the extension tube 94
to the ingress channel 68 may include directing a distal end of the
extension tube 94 over the outer surface of the ingress channel 68,
which may also include one or more barbs 96. The extension tube 94
may then be secured with a collet 98 and in a manner that is
similar to the methods described above. Another collet 100 may be
used to secure the extension tube 94 to the outflow port 66 of the
pump 58.
[0027] With the fluidic coupling complete, the circulatory assist
system 10 may be used to aid the heart 12 in pumping the patient's
blood through the vascular network as was shown in FIG. 1.
Accordingly, blood flow can proceed in the native manner with
oxygenated blood traveling from the left atrium 18 into the left
ventricle 22 to the aorta 38. From the aorta 38, blood moves into
the left subclavian artery 40, the left common carotid 42, and the
brachiocephalic trunk 44. Blood flow may also proceed along the
artificial path by entering the flexible cannula body 50 from the
left atrium 18 and traveling through the lumen of the flexible
cannula body 50 to the pump 58.
[0028] From the pump 58, blood flows into the bifurcated outflow
cannula 64, which is then distributed in a manner that is
consistent with the selected retrograde:radial ratio. For example,
with the illustrated bifurcated outflow cannula 64 having the
retrograde:radial ratio of 80:20, the majority of the blood will be
directed in the retrograde direction. Because the pump 58 is
typically operated within a range of about 2 L/min to about 3 L/min
and the native flow rate of the right subclavian artery 46 is about
0.5 L/min, the blood pumped in the retrograde direction will
overpower the native flow into the right subclavian artery 46.
Accordingly, the net blood flow in the right subclavian artery 46
that is distal to the first egress channel 70 will be in the
retrograde direction into the brachiocephalic trunk 44, and even
the aorta 38. From there, the blood is redistributed, for example,
into other arteries, such as the carotid arteries 42, 48 and the
vertebral artery 104. The other 20% of the blood flow is directed
radially, in the native blood flow direction of the right
subclavian artery 46 and, accordingly, will enter the axillary
artery 106 and the brachial artery 108 of the right arm 112. In
this way, blood is supplied to the patient's right arm 112 or the
extremity downstream of the select artery while not overwhelming
the venous capacity to remove the same and thus eliminating
edema.
[0029] In some patients, there may be a time after the surgery in
which the circulatory assist system 10 is no longer necessary.
Thus, it would be beneficial to remove the unnecessary components,
such as the implantable pump 58 and the flexible cannula body 50.
However, the decrease in blood flow in the portion of the right
subclavian artery 46 between the stent grafts 74, 76 will have
caused the vessel to thrombus completely and become occluded within
a short time after the circulatory assist system 10 is implanted.
One exemplary method of reversing the procedure and continuing
blood flow through the right subclavian artery 46 is illustrated in
FIG. 4.
[0030] As shown, once the pump 58 (FIG. 1) and flexible cannula
body 50 (FIG. 1) have been removed, the extension tube 94 (FIG. 2)
and bifurcated outflow cannula 64 (FIG. 2) are also removed. The
stent grafts 74, 76 are then coupled together using a U-shaped
adaptor 114. The U-shaped adaptor 114 may be constructed in a
manner that is similar to the bifurcated outflow cannula 64 (FIG.
3), namely, machined from a metallic material and polished, or
molded from a polymeric material. The adaptor 114 may include barbs
(not shown) located near the ingress and egress openings, in a
manner similar to the bifurcated outflow cannula 64 (FIG. 3), for
attaching the first and second stent grafts 74, 76. Collets 116,
118 may then be used to secure the stent grafts 74, 76 to the
adaptor 114.
[0031] With the circulatory assist system 10 (FIG. 1) removed,
blood will flow only in accordance with the native path, which was
described in detail above. Blood entering the right subclavian
artery 46 will be unable to traverse the portion of the vessel
residing between the stent grafts 74, 76. Instead, blood will flow
through the stent grafts 74, 76 and the U-shaped adaptor 114 and
then to the axillary artery 106 (FIG. 1).
[0032] While the manner of reversing the procedure has been shown
with a U-shaped adaptor 114 and the right subclavian artery 46, it
would be understood that adaptors having other shapes could also be
used in other vascular structures.
[0033] FIGS. 5A and 5B illustrate a bifurcated outflow cannula 120
having an alternate Y-shaped configuration where egress channels
121, 122 are constructed to diverge angularly from the same point
distal to the ingress channel 123. Construction of the alternate
bifurcated outflow cannula 120 may be in accordance with the
methods described previously. The ingress channel 123 may include a
barb 124 for receiving an extension tube 94 (FIG. 2); however, it
would be understood that the ingress channel 123 could also couple
directly to the output port 66 (FIG. 1) of the pump 58 (FIG. 1),
with or without the use of a collet. To achieve a desired
retrograde:radial flow ratio, channel fittings 126, 128 may be
constructed and fitted into the egress channels 121, 122,
respectively. Each channel fitting 126, 128 will include an
internal lumen 130, 132 having an internal cross-sectional area for
determining the retrograde:radial flow ratio. The channel fittings
126, 128 may include barbs 134, 136 for coupling to the respective
egress channel 121, 122. Glue, epoxy, or welding may be used to
secure the channel fittings 126, 128. Additional barbs 138, 140 may
be included on the channel fittings 126, 128 for receiving the
stent grafts 74, 76 (FIG. 1).
[0034] FIGS. 6 and 7 illustrate yet two additional manners of
constructing the bifurcated outflow cannula 120 where the desired
retrograde:radial ratio is selected by the inclusion of a flow
selector. The flow selectors in FIG. 6 include irises 141, 142
having different inner diameters; the flow selectors in FIG. 7
include rings 144, 146 also having different inner diameters. While
these figures specifically illustrate the flow selectors within the
egress channels 121, 122, it would be understood that the flow
selectors could be positioned alternatively, or additionally, in
the ingress channel 123, a position between the ingress channel 123
and one of the egress channels 121, 122, or in a combination of
these positions. Further, it would be understood that the flow
selectors could be positioned in any one of the various embodiments
of the bifurcated outflow cannula and can be mixed to suit a
particular function.
[0035] FIG. 8 illustrates yet another alternate configuration of
the bifurcated outflow cannula 148, formed as a t-connector. In
this particular configuration, the egress channels 150, 152 form a
90.degree. angle with respect to the ingress channel 154 and form a
180.degree. angle therebetween. While the illustrative embodiment
is shown with an 80:20 ratio, which was molded or machined, it
would be understood that the channel fittings 126, 128 of FIGS. 5A
and 5B could alternatively be used. One or more of the channels
150, 152, 154 may be constructed with barbs 156, 158, 160 for
securing the stent grafts 74, 76 (FIG. 2) as described
previously.
[0036] It would be appreciated by one skilled in the art that the
egress channels need not necessarily direct blood into the same
arterial vessel. FIG. 9 illustrates another method of using the
bifurcated cannula 64 where the first stent graft 74 enters the
aorta 38 at the first vascular incision 82a and the second stent
graft 76 enters the left subclavian artery 40 at the second
vascular incision 84a. In this way, the low volume blood flow is
directed into the left subclavian artery 40 for the left arm 162
while the high volume blood flow is directed into the aorta 38 for
distribution amongst the left subclavian artery 40, the left common
carotid 42, and the brachiocephalic trunk 44. FIG. 9 also
illustrates the flexible cannula body 50 being surgically
positioned into the left atrium 18.
[0037] While only a few specific configurations are shown, it would
be understood that various arrangements are possible having a
single ingress channel and two egress channels.
[0038] While the present invention has been illustrated by a
description of various preferred embodiments and while these
embodiments have been described in some detail, it is not the
intention of the Applicant to restrict or in any way limit the
scope of the appended claims to such detail. Additional advantages
and modifications will readily appear to those skilled in the art.
The various features of the invention may be used alone or in any
combination depending on the needs and preferences of the user.
This has been a description of the present invention, along with
the preferred methods of practicing the present invention as
currently known. However, the invention itself should only be
defined by the appended claims.
* * * * *