Perfusion catheter providing segmented flow regions and methods of use

Apparatus and methods are provided for delivering oxygenated blood at a first flow rate to a first region of the body and at a second lower flow rate to a second region of the body using first and second balloons and a first lumen that delivers blood to a first plurality of apertures interposed between the first and second balloons. A second lumen is used to deliver blood to a second plurality of apertures disposed proximally of the second balloon. Methods of using the apparatus also are provided.

FIELD OF THE INVENTION 
The present invention relates to catheters used to return oxygenated blood 
from a cardiopulmonary bypass machine to a patient during cardiac surgery. 
More specifically, the present invention relates to a perfusion catheter, 
and methods of use, that provide different flow rates to different regions 
of the body. 
BACKGROUND OF THE INVENTION 
Each year hundreds of thousands of people are afflicted with vascular 
diseases, such as arteriosclerosis, that result in cardiac ischemia. For 
more than thirty years, such disease, especially of the coronary arteries, 
has been treated using open surgical procedures, such as coronary artery 
bypass grafting. During such bypass grafting procedures, a sternotomy is 
performed to gain access to the pericardial sac, the patient is put on 
cardiopulmonary bypass, and the heart is stopped using a cardioplegia 
solution. 
More recently, techniques are being developed, for example, by Heartport, 
Inc., Redwood City, Calif., that permit cardiac surgery using an 
endoscopic approach, in which small access openings are created between 
the ribs and the bypass graft or heart valve repair procedure is performed 
guided by an image displayed on a video monitor. In the "keyhole" 
techniques developed by Heartport, the patient's heart is stopped and the 
patient is placed on cardiopulmonary bypass. Still other techniques being 
developed, for example, by CardioThoracic Systems, Inc., of Cupertino, 
Calif., enable such bypass graft procedures to be performed on a beating 
heart. 
In those techniques that involve stopping the heart to perform the surgery, 
blood flow to the heart is occluded, for example, by placing occlusion 
balloons in the ascending aorta and/or the vena cava. Venous blood is then 
withdrawn from the patient, for example, from the vena cava, and 
oxygenated using an extracorporeal oxygenation circuit. The oxygenated 
blood is then perfused into the patient in the vicinity of the ascending 
aorta to provide oxygenated blood to the brain, internal organs and 
extremities. 
U.S. Pat. No. 5,312,344 to Grinfeld et al. describes a multi-lumen 
perfusion catheter for perfusing oxygenated blood into a patient on 
cardiopulmonary bypass. The catheter has a distal balloon for occluding 
the ascending aorta, a first lumen for delivering cardioplegia solution 
through a first opening distal to the balloon, and a second lumen for 
perfusing oxygenated blood through a second opening proximal to the 
balloon. The catheter may be positioned in the ascending aorta either 
directly through an opening in the aorta, or in a retrograde manner via a 
femoral artery and the abdominal aorta. 
U.S. Pat. No. 4,173,981 to Mortensen describes an arterial perfusion 
catheter having a tapered shape and a plurality of openings along its 
length. When the catheter is positioned within a patient, one or more 
openings preferably are aligned with the branch vessels in the aortic 
arch, the renal arteries, the iliac bifurcation, and the internal iliac 
artery. 
The foregoing catheters have a number of disadvantages. In particular, 
multi-lumen catheters, such as described in Grinfeld et al., must have a 
large diameter to provide oxygenated blood sufficient to perfuse the whole 
body. In addition, because the foregoing catheters preferably are 
positioned with the blood perfusion openings in predetermined locations, a 
variety of catheters of different lengths must be available for use in 
patients of different sizes. 
The perfusion system described in the literature by Heartport, Inc., 
Redwood City, Calif., comprises an "endo-aortic clamp" ("EAC") portion and 
an arterial return catheter ("ARC"). The EAC, which comprises a catheter 
having a balloon for occluding the aortic root, and a lumen for delivering 
cardioplegia distal to the balloon, passes through the ARC. The ARC 
extends only a short distance into the patient's femoral artery. 
Oxygenated blood is perfused through the annulus formed by the ARC and the 
EAC and in a retrograde manner in the aorta. 
A drawback associated with all of the foregoing perfusion systems is that 
all require relatively high performance pumps to deliver flow rates high 
enough to perfuse the entire body. In multi-lumen catheter designs, the 
pressure drop encountered in delivering a high flow rate proximal to the 
occlusion balloon favors the use of larger diameter lumens, thereby 
resulting in catheters having a profile too large to fit many patients 
having smaller frames or vessels. 
Similarly, in the Heartport system, the need to perfuse the blood in a 
retrograde fashion along the length of the aorta requires a high 
performance pump. This is especially so because the oxygenated blood is 
perfused into the iliac artery, where the degree of oxygenation is 
relatively low, and must then flow in a retrograde manner through the 
aorta to reach the aortic arch, where the highest flow rates are required 
to preserve the brain. 
In view of the foregoing, it would be desirable to provide apparatus and 
methods for delivering oxygenated blood to a patient from a 
cardiopulmonary bypass machine, and that overcome the drawbacks of 
previously known perfusion catheters. 
It further would be desirable to provide apparatus and methods for 
delivering oxygenated blood to a patient that permit the use of one or 
more lower performance pumps than has heretofore been possible. 
It still further would be desirable to provide apparatus and methods for 
delivering flow rates to different regions of the body in proportion to 
the degree of oxygenation required by those different regions. 
SUMMARY OF THE INVENTION 
In view of the foregoing, it is an object of this invention to provide 
apparatus and methods for delivering oxygenated blood to a patient from a 
cardiopulmonary bypass machine, and that overcome the drawbacks of 
previously known perfusion catheters. 
It is a further object of the present invention to provide apparatus and 
methods for delivering oxygenated blood to a patient that permit the use 
of one or more lower performance pumps than has heretofore been possible. 
It is another object of this invention to provide apparatus and methods for 
delivering flow rates to different regions of the body in proportion to 
the degree of oxygenation required by those different regions. 
These and other objects of the invention are accomplished by providing a 
perfusion catheter having a first and second balloons, a first lumen 
capable of delivering oxygenated blood to a first plurality of apertures 
interposed between the first and second balloons, and a second lumen 
capable of delivering blood to a second plurality of apertures disposed 
proximally of the second balloon. In accordance with the principles of the 
present invention, the perfusion catheter delivers oxygenated blood at a 
first flow rate to the region between the first and second balloons, and 
delivers oxygenated blood at a second flow rate to the region proximal of 
the second balloon. 
In one embodiment, the perfusion catheter includes a first inlet port 
communicating with the first lumen, and a second inlet port communicating 
with the second lumen. The first and second lumens may be sized so that, 
when coupled to an outlet of a single cardiopulmonary bypass machine, the 
flow rates exiting the first and second pluralities of apertures are 
adequate to provide whole body perfusion. The first and second balloons 
and first and second lumens may be integral in a single multi-lumen 
catheter. 
Alternatively, the first balloon and first lumen may form part of a first 
catheter and the second balloon and second lumen may form part of a second 
catheter that is longitudinally adjustable relative to the first catheter. 
The first catheter delivers oxygenated blood at a first flow rate to a 
first region of the body defined by placement of the first and second 
balloons, while the second catheter delivers oxygenated blood at a second 
flow rate to a second region of the body. 
As further alternative, the first and second balloons, and first lumen may 
form part of a first catheter that is inserted via a first access site to 
perfuse a first region of the body while the second lumen may form part of 
a second catheter that is inserted via a second access site to perfuse a 
second region of the body.

DETAILED DESCRIPTION OF THE INVENTION 
The present invention provides a perfusion catheter that provides different 
flow rates of oxygenated blood to different regions of a patient's body. 
Perfusion catheters constructed in accordance with the principles of the 
present invention are based on the observation that, during cardiac 
surgery, some regions of the body, such as the brain, require near-normal 
blood flow rates to avoid injury, while other regions of the body, such as 
the lower extremities, can tolerate much lower blood flow rates without 
injury. It is expected that the perfusion catheters of the present 
invention may reduce the need for high performance pumps by reducing the 
overall volume of blood that must be perfused into the body by up to 40%. 
Specifically, the perfusion catheters of the present invention enable 
smaller, lower performance pumps to be used to provide high flow rates, 
but at reduced volumes, to critical areas of the body, such as the branch 
vessels of the aortic arch. A second lumen is provided for delivering 
oxygenated blood to the remainder of the body, but at much lower flow 
rates. Unlike the multi-lumen catheter described in the Grinfeld et al. 
patent, the catheters of the present invention do not attempt to provide 
whole-body perfusion. Accordingly, the portion of the catheter that 
extends into the aortic arch may be much smaller in diameter. Moreover, 
because the remainder of the body is perfused at a lower flow rate, a 
smaller diameter lumen also may be used. 
Referring to FIG. 1, an illustrative perfusion catheter constructed in 
accordance with the principles of the present invention is described. 
Catheter 10 comprises distal end 11 having radioopaque marker band 11a, 
outlet port 12, distal balloon 13, apertures 14, proximal balloon 15 and 
apertures 16. Proximal end 17 of catheter 10 includes blood inlet ports 18 
and 19, balloon inflation ports 20 and 21, and cardioplegia injection port 
22. Catheter 10 is shown positioned within aorta A with distal balloon 13 
positioned near aortic root AR, proximal balloon 15 positioned just below 
renal arteries R, and the proximal portion of the catheter exiting through 
a cut-down in femoral artery F. 
Referring now also to FIG. 2, lumen 23 couples cardioplegia injection port 
22 to outlet port 12. Lumen 24 couples balloon inflation port 20 to distal 
balloon 13, while lumen 25 couples balloon inflation port 21 to proximal 
balloon 15. Lumen 26 couples blood inlet port 18 to apertures 14, while 
lumen 27 couples blood inlet port 19 to apertures 16. 
Cardioplegia solution injected into cardioplegia injection port 22 exits 
catheter 10 through outlet port 12. Oxygenated blood pumped into catheter 
10 via blood inlet port 18 exits the catheter only through apertures 14, 
while blood pumped into catheter 10 via blood inlet port 19 exits the 
catheter only through apertures 16. One or more apertures 28 communicate 
inflation medium injected via balloon inflation port 20 and lumen 24 with 
the interior of balloon 13. Likewise, one or more apertures 29 communicate 
inflation medium injected via balloon inflation port 21 and lumen 25 with 
the interior of balloon 15. 
Catheter 10 may be constructed of any of a number of materials commonly 
used in catheter construction, such as polyethylene, polyurethane, or 
polyvinylchloride. Distal balloon 13 and proximal balloon 15 may comprise 
a noncompliant or semi-compliant material, such as polyethylene, 
polyurethane, or nylon. Inlet ports 18-22 are equipped with standard luer 
connections that permit coupling to a source of inflation medium, 
cardioplegia solution, and a cardiopulmonary bypass machine, respectively. 
In accordance with the principles of the present invention, catheter 10 may 
be coupled to a cardiopulmonary bypass machine so that blood may be pumped 
through apertures 14 in the region of the aorta between balloons 13 and 15 
at a flow rate of up to 7-8 liters/minute, and blood may be pumped through 
apertures 16 at flow rates of up to 3-4 liters/minute. Blood inlet ports 
18 and 19 therefore may be coupled to two separate pumps, or coupled to a 
Y-shaped connector (not shown) on the outlet of a single pump. In the 
latter case, the diameters of lumens 26 and 27 may be selected to provide 
the desired flow rates. 
In operation, catheter 10 first is positioned in a patient's aorta via a 
femoral cut-down, and then advanced so that distal end 11 is positioned in 
the ascending aorta, for example, as determined by fluoroscopy and 
suitable radioopaque marker 11a. Once the catheter is in place and 
connected to a cardiopulmonary bypass machine, distal balloon 13 is 
inflated. Cardioplegia solution then is injected via port 22, lumen 23 and 
outlet port 12 to stop the heart. Proximal balloon 15 is inflated, and the 
cardiopulmonary bypass machine may then be activated to perfuse the upper 
and lower regions of the body at different flow rates. 
Advantageously, because the total volumetric flow rate required to perfuse 
the body using catheter 10 is expected to be significantly lower than 
previously known perfusion arrangements, lower performance, less costly 
pumps may be used. This in turn may contribute to an overall reduction in 
the cost of the bypass procedure. 
Referring now to FIG. 3, an alternative embodiment of a perfusion catheter 
constructed in accordance with the present invention is described. 
Catheter 30 comprises inner catheter 31 disposed for sliding movement in 
outer catheter 32. Inner catheter 31 comprises distal end 33 having 
radioopaque marker band 33a, outlet port 34, distal balloon 35 and 
apertures 36. Outer catheter 32 comprises proximal balloon 37, apertures 
38 and endcap 39 including radioopaque marker band 39a. Proximal end 40 of 
catheter 30 includes blood inlet ports 41 and 42, balloon inflation ports 
43 and 44, and cardioplegia injection port 45. Catheter 30 is shown 
positioned within aorta A with distal balloon 35 positioned near aortic 
root AR, proximal balloon 37 positioned just below renal arteries R, and 
the proximal portion of the catheter exiting through a cut-down in femoral 
artery F. 
Referring now also to FIG. 4, lumen 46 couples cardioplegia injection port 
45 to outlet port 34. Lumen 47 couples balloon inflation port 43 to distal 
balloon 35, while lumen 48 couples balloon inflation port 44 to proximal 
balloon 37. Lumen 49 couples blood inlet port 41 to apertures 36. Annulus 
50, defined by the exterior of inner catheter 31 and the interior surface 
of catheter 32 forms a lumen that couples blood inlet port 42 to apertures 
38. 
Cardioplegia solution injected into cardioplegia injection port 45 exits 
inner catheter 31 through outlet port 34. Oxygenated blood pumped into 
inner catheter 31 via blood inlet port 41 exits the catheter only through 
apertures 36, while blood pumped into catheter 30 via blood inlet port 42 
exits the outer catheter 32 only through apertures 38. One or more 
apertures 51 communicate inflation medium injected via balloon inflation 
port 43 and lumen 47 with the interior of distal balloon 35. Likewise, one 
or more apertures 52 communicate inflation medium injected via balloon 
inflation port 44 and lumen 48 with the interior of proximal balloon 37. 
As shown in FIG. 5, inner catheter 31 preferably is disposed concentrically 
in outer catheter 32 for sliding movement by O-rings 55 disposed in 
recesses 56 of endcap 39. Accordingly, the longitudinal spacing between 
distal balloon 35 and proximal balloon 37 may be adjusted by sliding inner 
catheter 31 relative to outer catheter 32. Consequently, catheter 30 may 
be used for a variety of patients of different size, with the spacing 
between the distal and proximal balloons adjusted on a per-patient basis. 
Radioopaque markers 33a and 39a assist in visualizing this positioning of 
the catheter under fluoroscopic guidance. 
Catheters 31 and 32, and endcap 39, may be constructed of any of the 
materials described hereinabove, such as polyethylene, polyurethane, or 
polyvinylchloride, while balloons 35 and 37 likewise may comprise a 
noncompliant or semi-compliant material, as described above. O-rings 55 
preferably comprise a biocompatible material, such as silicone or 
polytetrafluoroethylene. Inlet ports 41-45 preferably are equipped with 
standard luer connections, as described hereinabove. 
Catheter 30 may be coupled to a single or multiple pumps, as described 
hereinabove. If catheter 30 is to be designed so that blood inlet ports 41 
and 42 are to be coupled to a single pump using a Y-connection, the 
diameters of lumens 49 and 50 may be selected to control the flow rates 
delivered through apertures 36 and 38. 
Operation of catheter 30 is similar to that described hereinabove with 
respect to catheter 10. In particular, catheter 30 first is positioned in 
a patient's aorta via a femoral cut-down, and then advanced so that distal 
end 33 is positioned in the ascending aorta, for example, as determined by 
fluoroscopy and radioopaque marker 33a. Outer catheter 32 is then adjusted 
in the proximal and distal directions until proximal balloon 37 is 
disposed in a desired position, e.g., either above or below renal arteries 
R, as determined by fluoroscopy and radioopaque marker 39a. 
Once catheter 30 is in place and connected to a cardiopulmonary bypass 
machine, distal balloon 35 is inflated. Cardioplegia solution then is 
injected via port 45, lumen 46 and outlet port 34 to stop the heart. 
Proximal balloon 37 is inflated, and the cardiopulmonary bypass machine 
may then be activated to perfuse the upper and lower regions of the body 
at different flow rates. Catheter 30 provides not only the advantages of 
catheter 10, described hereinabove, but also permits the catheter to be 
employed in patients of different sizes by adjusting the spacing the 
distal and proximal balloons. 
With respect to FIG. 6, a further alternative embodiment of a perfusion 
catheter of the present invention, suitable for very small frame patients, 
is described. Catheter 60 comprises distal end 61 having radioopaque 
marker band 61a, outlet port 62, distal balloon 63, apertures 64, and 
proximal balloon 65. Proximal end 66 of catheter 60 includes blood inlet 
port 67, balloon inflation ports 68 and 69, and cardioplegia injection 
port 70. Catheter 60 is used in conjunction with return catheter 75. 
Return catheter 75 comprises a single lumen catheter having distal end 76 
including radioopaque marker band 76a, plurality of apertures 77 and 
proximal end 78 including luer fitting 79 for connecting the catheter to a 
cardiopulmonary bypass machine. 
Catheter 60 is shown in FIG. 6 positioned within aorta A with distal 
balloon 63 positioned near aortic root AR, proximal balloon 65 positioned 
just below renal arteries R, and the proximal portion of the catheter 
exiting through a cut-down in femoral artery F.sub.1. Return catheter 75 
is positioned in aorta A with distal end 76 disposed above iliac 
bifurcation IB, and exits through a cut-down in femoral artery F.sub.2. 
Referring now also to FIG. 7, lumen 80 couples cardioplegia injection port 
70 to outlet port 62. Lumen 81 couples balloon inflation port 68 to distal 
balloon 63, while lumen 82 couples balloon inflation port 69 to proximal 
balloon 65. Lumen 83 couples blood inlet port 67 to apertures 64. 
Apertures 64 preferably are arranged in two groups along the length of 
catheter 60, so that first group 64a is disposed in the aortic arch and 
second group 64b is disposed adjacent renal arteries R. 
Cardioplegia solution injected into cardioplegia injection port 70 exits 
catheter 60 through outlet port 62. Oxygenated blood pumped into catheter 
60 via blood inlet port 67 exits the catheter only through apertures 64. 
One or more apertures 84 communicate inflation medium injected via balloon 
inflation port 68 and lumen 81 with the interior of distal balloon 63. 
Likewise, one or more apertures 85 communicate inflation medium injected 
via balloon inflation port 69 and lumen 82 with the interior of proximal 
balloon 65. 
Catheters 60 and 75, and balloons 63 and 65 may be constructed of any of 
the materials described hereinabove. Inlet ports 67-70 and 79 preferably 
are equipped with standard luer connections, as described hereinabove. 
Radioopaque markers 61a and 76a assist in positioning the catheters under 
fluoroscopic guidance. 
Use of catheters 60 and 75 is now described. Catheter 60 first is 
positioned in a patient's aorta via a femoral cut-down in femoral artery 
F.sub.1, and then advanced so that distal end 61 is positioned in the 
ascending aorta, for example, as determined by fluoroscopy and radioopaque 
marker 61a. Return catheter 75 is positioned in the patient's aorta, below 
the position of balloon 65 and above iliac bifurcation IB, via a femoral 
cut-down in femoral artery F.sub.2, as determined by fluoroscopy and 
radioopaque marker 76a. 
Once catheters 60 and 75 are in place and connected to a cardiopulmonary 
bypass machine, distal balloon 63 is inflated to occlude the aorta. 
Cardioplegia solution then is injected via port 70, lumen 80 and outlet 
port 62 to stop the heart. Proximal balloon 65 is inflated, and the 
cardiopulmonary bypass machine then may be activated to perfuse the upper 
region of the body at a first flow rate via blood inlet port 67, lumen 83, 
and apertures 64. Catheter 75 is used to perfuse the lower region of the 
body at a second, lower, flow rate. Catheters 60 and 75 therefore provide 
many of the advantages of catheters 10 and 30, described hereinabove, but 
also permit the catheter system to be employed in patients of very small 
size or having very small femoral arteries. 
While preferred illustrative embodiments of the invention are described 
above, it will be apparent to one skilled in the art that various changes 
and modifications may be made therein without departing from the 
invention. For example, the various lumens depicted in the illustrative 
cross-sections of FIGS. 2, 4, 5 and 7 may have alternative arrangements, 
and it is intended in the appended claims to cover all such changes and 
modifications which fall within the true spirit and scope of the 
invention.