Abstract:
The present invention takes the form of a catheter or cannula having a deployable aortic flow divider mounted on an elongated catheter shaft. The elongated catheter shaft is adapted for introduction into a patient&#39;s ascending aorta either by a direct aortic puncture or by a peripheral arterial approach. The aortic flow divider has an undeployed state where it is compressed or wrapped around the catheter shaft and a deployed state where it expands within the aortic lumen. The aortic flow divider is configured to provide embolic protection to the patient&#39;s brain and to the coronary arteries of the heart during cardiac surgery and other procedures involving cardiopulmonary bypass or circulatory support. One or more flow channels near the upstream end of the aortic flow divider direct a flow of blood from the superior aortic arch into the aortic root, which creates a washing action that directs potential emboli out of the aortic root and away from the coronary arteries.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to an arterial perfusion catheter or cannula for infusion of oxygenated blood or other fluids into a patient for cardiopulmonary bypass or circulatory support. More particularly, it relates to an arterial perfusion catheter with a deployable aortic flow divider for protecting a patient&#39;s brain and heart from adverse effects due to embolization that may occur during cardiac surgery and other procedures involving cardiopulmonary bypass or circulatory support.  
         BACKGROUND OF THE INVENTION  
         [0002]    Over the past decades tremendous advances have been made in the area of heart surgery, including such life-saving surgical procedures as coronary artery bypass grafting (CABG) and cardiac valve repair or replacement surgery. Typically, in order to gain access to the heart a median sternotomy is performed, which creates an open surgical field, conducive for the placement of cannulae and direct visualization for performing the required procedure. Heart activity generally ceases for some period of time, and cardiopulmonary support is provided by diverting blood through an extracorporeal circuit to maintain sufficient oxygenated blood flow to the body and brain while the heart is arrested. Cardiopulmonary bypass (CPB) is a technology that has helped to make these advances possible.  
           [0003]    Recently, however, there has been a growing awareness within the medical community, and among the patient population as well, concerning the adverse affects associated with heart surgery, the trauma associated with median sternotomies, as well as well the physiological reactions associated with cardiopulmonary bypass. Chief among these concerns is the potential for stroke or neurologic deficit.  
           [0004]    Clinical research has indicated that one of the primary causes of stroke or neurologic deficit is cerebral embolization. Emboli vary in size as well as physical properties and their sources vary. However, embolic materials include atherosclerotic plaques or calcific plaques residing within the ascending aorta or cardiac valves and thrombus or clots from within the chambers of the heart. Emboli may also be dislodged during surgical manipulation of the heart or ascending aorta, aortic cross-clamping, aortic cannulation or due to high velocity jetting from the aortic perfusion cannula (sometimes called the “sandblasting effect”). In addition, air can enter the heart chambers or the blood stream during surgery through open incisions or through the aortic perfusion cannula from the CPB system. Lipid emboli may also enter through the CPB system, particularly when blood salvaged using cardiotomy suction is reintroduced into the circulation. (Brooker R F, Brown W R, Moody D M, et al.  Cardiotomy suction: a major source of brain lipid emboli during cardiopulmonary bypass . Annals of Thoracic Surgery, June 1998, 65(6) p1651-5.) As blood is pumped to the brain, either through the extracorporeal circuit or by the beating heart in an off-pump minimally invasive procedure, transient or mobile emboli can become lodged in a vessel of the brain causing a stroke or other neurologic deficit. Clinical studies have shown a correlation between the number and size of emboli passing through the carotid arteries and the frequency and severity of neurologic damage. At least one study has found that frank strokes seem to be associated with macroemboli larger than approximately 100 micrometers in size, whereas more subtle neurologic deficits seem to be associated with multiple microemboli smaller than approximately 100 micrometers in size. In order to improve the outcome of cardiac surgery and avoid adverse neurological effects it would be very beneficial to eliminate or reduce the potential of such cerebral embolic events.  
           [0005]    Other devices for embolic protection during cardiac surgery are described in: U.S. Pat. No. 6,254,563 Perfusion shunt apparatus and method, U.S. Pat. No. 6,139,517 Perfusion shunt apparatus and method, U.S. patent application Ser. No. 09/378,676, filed Aug. 20, 1999, Perfusion filter catheter, U.S. patent application Ser. No. 09/158,405, filed Sep. 22, 1998, Aortic catheter with flow divider and methods for preventing cerebral embolization, U.S. patent application Ser. No. 09/447,458, filed Feb. 28, 2001, Cerebral embolic protection assembly and associated methods, and PCT International Patent Application WO 0043062 Aortic catheter with flow divider and methods for preventing cerebral embolization. These patents and patent applications, and all other patents and patent applications referred to herein, are hereby incorporated by reference in their entirety for all purposes. While these previous devices represent a significant advance in technology available for embolic protection during cardiac surgery, there continues to be a need for further research and improvements in this area. In particular, there is a continued need for a device that provides embolic protection to the brain and to the coronary arteries of the heart during cardiac surgery and other procedures involving cardiopulmonary bypass.  
           [0006]    The terms downstream and upstream, when used herein in relation to the patient&#39;s vasculature, refer to the direction of blood flow and the direction opposite that of blood flow, respectively. In the arterial system, downstream refers to the direction further from the heart along the arterial network, while upstream refers to the direction closer to the heart. The terms proximal and distal, when used herein in relation to instruments used in the procedure, refer to directions closer to and farther away from the operator performing the procedure. Since the present invention is not limited to peripheral or central approaches, the device should not be narrowly construed when using the terms proximal or distal since device features may be slightly altered relative to the anatomical features and the device position relative thereto.  
         SUMMARY OF THE INVENTION  
         [0007]    In keeping with the foregoing discussion, the present invention takes the form of a catheter or cannula having a deployable aortic flow divider mounted on an elongated catheter shaft. The elongated catheter shaft is adapted for introduction into a patient&#39;s ascending aorta either by a direct aortic puncture or by a peripheral arterial approach. The aortic flow divider has an undeployed state where it is pressed against or wrapped around the catheter shaft and a deployed state where it expands within the aortic lumen. The aortic flow divider is configured to provide embolic protection to the patient&#39;s brain and the coronary arteries of the heart during cardiac surgery and other procedures involving cardiopulmonary bypass or circulatory support.  
           [0008]    Radiopaque markers and/or sonoreflective markers may be located on the catheter and/or aortic flow divider. Preferably, one or more perfusion lumens extend through the elongated catheter shaft to one or more perfusion ports upstream and/or downstream of the aortic flow divider. Oxygenated blood is perfused through the perfusion lumen, or is supplied by the beating heart or a combination of both. Embolic materials that might be dislodged within the heart or ascending aorta are rerouted away from the cerebral circulation by the aortic flow divider.  
           [0009]    In use, the aortic flow divider is introduced into the patient&#39;s aorta, either by a peripheral arterial approach or by direct aortic puncture, with the aortic flow divider in a collapsed state. The aortic flow divider is advanced across the aortic arch and positioned with the upstream end of the divider in the ascending aorta between the aortic valve and the brachiocephalic artery. The aortic flow divider is then deployed within the aortic arch. When deployed, the aortic flow divider takes on the configuration of a wing or baffle that hemodynamically separates blood flow in the aorta into a first channel that delivers oxygenated blood to the aortic arch vessels and cerebral circulation and a second channel that delivers oxygenated blood to the corporeal circulation. This hemodynamic flow separation reduces the embolic load to the brain by rerouting potential emboli away from the cerebral circulation. In addition, one or more flow channels, preferably located near the upstream end of the aortic flow divider, direct a flow of oxygenated blood from the superior aortic arch into the aortic root, which creates a washing action that directs potential emboli out of the aortic root and away from the coronary ostia.  
           [0010]    The position of the catheter and the deployment state of the aortic flow divider may be monitored using fluoroscopy, ultrasound, transesophageal echography (TEE) or aortic transillumination using visible, infrared or near infrared light. Once the aortic flow divider is deployed, oxygenated blood may be infused into the aorta through the perfusion lumen or alternatively the beating heart may supply all the blood or a combination of both. Any potential emboli are rerouted by the aortic flow divider and are thereby prevented from entering the neurovasculature. After use, the aortic flow divider is returned to the collapsed position and the catheter is withdrawn from the patient.  
           [0011]    Methods according to the present invention are described using the aortic catheter for partitioning the patient&#39;s aortic lumen and performing selective aortic perfusion. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is a perspective drawing of an aortic perfusion catheter having two perfusion lumens with a deployable aortic flow divider shown in the deployed or inflated state.  
         [0013]    [0013]FIG. 2 is a top view of a distal portion of the perfusion catheter of FIG. 1 with the aortic flow divider shown in the undeployed or deflated state.  
         [0014]    [0014]FIG. 3 is a cross section of the perfusion catheter of FIG. 1 taken along the line  3 - 3 .  
         [0015]    [0015]FIG. 4 is a cross section of the perfusion catheter of FIG. 1 taken along the line  4 - 4 .  
         [0016]    [0016]FIG. 5 is a cross section of the perfusion catheter of FIG. 1 taken along the line  5 - 5 .  
         [0017]    [0017]FIG. 6 is an exploded view showing the shaft construction of the perfusion catheter of FIG. 1.  
         [0018]    [0018]FIG. 7 is a cross section of the perfusion catheter of FIG. 1 taken along the line  7 - 7 .  
         [0019]    [0019]FIG. 8 is a side perspective view of a distal end portion of the aortic catheter of FIG. 1.  
         [0020]    [0020]FIG. 9 is a cutaway perspective view of a distal end portion of the aortic catheter of FIG. 1.  
         [0021]    FIG  10  is a cutaway view of a distal end portion of the aortic catheter of FIG. 1 showing the shaft construction.  
         [0022]    FIG  11  shows a flow diagram of the perfusion catheter of FIG. 1 with the aortic flow divider deployed within a patient&#39;s aortic arch.  
         [0023]    [0023]FIG. 12 is a perspective drawing of a perfusion catheter having a single perfusion lumen with a deployable aortic flow divider shown in the deployed or inflated state.  
         [0024]    [0024]FIG. 13 is a top view of a distal portion of the perfusion catheter of FIG. 12 with the aortic flow divider shown in the undeployed or deflated state.  
         [0025]    [0025]FIG. 14 is a side view of the perfusion catheter of FIG. 12 with the aortic flow divider shown in an uninflated state positioned alongside an insertable obturator.  
         [0026]    [0026]FIG. 15 shows a flow diagram of the perfusion catheter of FIG. 12 with the aortic flow divider deployed within a patient&#39;s aortic arch.  
         [0027]    [0027]FIG. 16 shows a flow diagram of a perfusion catheter with an aortic flow divider deployed within a patient&#39;s aortic arch via a peripheral artery insertion site. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0028]    FIGS.  1 - 11  show an aortic catheter  200  with an aortic flow divider  210  configured for performing differential perfusion of a patient&#39;s circulatory system. FIG. 1 shows a perspective view of the aortic catheter  200 . In this illustrative example, the aortic catheter  200  is configured for central introduction into the aortic arch through an aortotomy in the ascending aorta. The aortic catheter  200  could alternatively be configured for introduction via peripheral arterial access. The aortic flow divider  210  is mounted on a distal portion of an elongated catheter shaft  202 . The catheter shaft  202 , shown in cross section in FIG. 5, is constructed with three lumens: an arch perfusion lumen  204 , a corporeal perfusion lumen  206  and an inflation lumen  208 . The arch perfusion lumen  204  extends through the catheter shaft  202  and communicates on its distal end with one or more arch perfusion ports  212 , which are located on an upper surface  214  of the aortic flow divider  210 . The proximal end of the arch perfusion lumen  204  connects to an arch perfusion extension tube  216 , shown in cross section in FIG. 3, which terminates in an arch perfusion connector  218 , such as a barb fitting with a Luer-lock side branch or the like. The corporeal perfusion lumen  206  extends through the catheter shaft  202  and communicates on its distal end with a corporeal perfusion end port  220  and/or corporeal perfusion side ports, which are located near the distal end of catheter shaft  202  and preferably downstream of and below the aortic flow divider  210 . Alternatively or in addition, one or more corporeal perfusion ports  220 ′ may be located near the upstream end of the aortic flow divider  210 . The proximal end of the corporeal perfusion lumen  206  connects to a corporeal perfusion extension tube  224 , shown in cross section in FIG. 4, which terminates in a corporeal perfusion connector  226 , such as a barb fitting with a Luer-lock side branch or the like.  
         [0029]    The inflation lumen  208  extends through the catheter shaft  202 , preferably within the arch perfusion lumen  204 , and connects on its distal end with an inflation port  228 , shown in FIGS. 9 and 10, which communicates with the interior of the inflation chamber  230  of the aortic flow divider  210 . The proximal end of the inflation lumen  208  connects to, or is continuous with, an inflation lumen extension tube  232 , which terminates in an inflation lumen connector  234 , such as a stopcock with a Luer-lock connector or the like. A manifold  236 , which is preferably an injection molded part, provides the junction where the catheter shaft  202 , the arch perfusion extension tube  216 , the corporeal perfusion extension tube  224  and the inflation lumen extension tube  232  join together. Optionally, a strain relief tube  203  may be provided to reinforce the junction between the manifold  236  and the catheter shaft  202 . Preferably, the aortic catheter  200  includes an inflation indicator  238  on the inflation lumen extension tube  232 . The inflation indicator  238  is a small, low-pressure balloon that is mounted on the inflation lumen extension tube  232 , such as by heat sealing or adhesive bonding. The interior of the inflation indicator  238  is connected to the inflation lumen  208  by an inflation indicator port  240  on the inflation lumen extension tube  232 . Alternatively, the balloon-shaped inflation indicator  238  may be formed integrally with the inflation extension tube  232 . The inflation indicator  238  inflates to provide a visual indication whenever the aortic flow divider  210  is inflated.  
         [0030]    The catheter shaft  202  may be formed as a multilumen extrusion or it may be formed as a composite construction made up of individual tubes. In one particularly preferred construction, the catheter shaft  202  is constructed by joining together three individual tubes representing the arch perfusion lumen  204 , the corporeal perfusion lumen  206  and the inflation lumen  208 . FIG. 6 shows an exploded view of the composite construction catheter shaft  202 . FIG. 10 shows the catheter shaft  202  with the aortic flow divider  210  removed to illustrate the composite construction more clearly. The corporeal perfusion lumen  206  is constructed as a D-shaped tube  246 , which is preferably reinforced over its entire length with a wire coil  248 . Similarly, the arch perfusion lumen  204  is constructed as a D-shaped tube  242 , which is reinforced over at least part of its length with a wire coil  244 . The wire coil  244  reinforcing the D-shaped tube  242  for the arch perfusion lumen  204  preferably extends from the proximal end of the catheter shaft  202  to an intermediate point located under the proximal end of the aortic flow divider  210 , and the D-shaped tube  242  continues unreinforced to the distal end of the catheter. A molded plastic tip plug  254  may be inserted into the distal end of the D-shaped tube  242  to terminate and seal the arch perfusion lumen  204  and a second internal plug  255  may be located within the arch perfusion lumen  204  just distal to the most distal arch perfusion port  212 . The inflation lumen  208  is constructed as a single lumen tube  250 , which, as noted above, may be continuous with the inflation lumen extension tube  232 . The three tubes  242 ,  246 ,  250  are then covered with a clear, thin-walled tube  252  and heated under pressure to create the composite construction shown in FIG. 5. One or more arch perfusion ports  212  are cut or drilled through the unreinforced wall of the arch perfusion lumen  204  in the distal portion catheter shaft  202 .  
         [0031]    A gentle S-shaped curve is set into the catheter shaft  202  by placing the catheter shaft  202  on a curved mandrel and heating it. The distal portion of the catheter shaft  202  where the aortic flow divider  210  will be mounted is given a curve that approximates the internal curvature of a human aortic arch. A depth stop  268  is attached to the exterior of the catheter shaft  202  slightly proximal to where the aortic flow divider  210  will be mounted. Preferably, the depth stop  268  is mounted slightly obliquely on the catheter shaft  202 , as shown in FIG. 10, so that it will lie flat against the outer wall of the aorta when the curved catheter shaft  202  is inserted through an aortotomy incision into the ascending aorta. Preferably, an orientation stripe  201  or other mark is printed on the exterior of the catheter shaft  202  to indicate the orientation of the aortic flow divider  210  once it has been inserted through the aortotomy incision into the ascending aorta.  
         [0032]    [0032]FIG. 2 shows a top view of a distal end portion of the aortic catheter  200  of FIG. 1 showing the aortic flow divider  210  in a deflated condition. FIG. 8 shows a side perspective view of the aortic flow divider  210  in an inflated condition. FIG. 9 shows a cutaway side perspective view of the aortic flow divider  210  in the inflated condition. The aortic flow divider  210  has an upper wall  214  and a lower wall  222  that enclose an inflation chamber  230 . The upper wall  214  and lower wall  222  of the aortic flow divider  210  are preferably constructed of a first and second sheet of plastic film that are joined to one another around their peripheral edges  256  and at one or more interior locations  258 , for example by heat sealing or adhesive bonding. Suitable materials for the upper wall  214  and lower wall  222  of the aortic flow divider  210  include, but are not limited to, polymers, elastomers, thermoplastics, polyvinylchloride, polyurethane, polyethylene, polyamides, polyesters, silicone, latex, and alloys or copolymers, and reinforced composites thereof. The plastic film that makes up the upper wall  214  and lower wall  222  may have the same or different thicknesses. For example, the upper wall  214  may be made of a thinner plastic film than the lower wall  222 .  
         [0033]    The aortic flow divider  210  is generally an elongated oval shape that is sized to fit within the lumen of a patient&#39;s aortic arch. In one particularly preferred embodiment, the upper wall  214  of the aortic flow divider  210  is slightly larger in length and width than the lower wall  222 . When the peripheral edges  256  of the upper wall  214  and lower wall  222  are heat sealed together, this creates a pair of longitudinal folds or wrinkles  260 ,  262  and at least one lateral fold or wrinkle  264  in the upper wall  214  when the aortic flow divider  210  is deflated, as seen in the top view in FIG. 2. These folds or wrinkles  260 ,  262 ,  264  create flow channels that assist the aortic flow divider  210  to deflate fully under applied vacuum.  
         [0034]    The interior seals  258  of the aortic flow divider  210  are located so that they will cover the arch perfusion ports  212  in the distal portion of the catheter shaft  202 . Holes  266  are cut through the interior seals  258  to coincide with each of the arch perfusion ports  212 . Once the aortic flow divider  210  is formed, it is adhesively bonded and/or heat bonded to the distal portion of the catheter shaft  202  with the holes  266  positioned over the arch perfusion ports  212 . Alternatively, the holes  266  through the interior seals  258  and the arch perfusion ports  212  may be drilled simultaneously after the aortic flow divider  210  has been bonded to the catheter shaft  202  to assure precise alignment. The distal end of the single lumen tube  250  is connected to the aortic flow divider  210  so that the inflation lumen  208  communicates with the inflation chamber  230  through the inflation port  228 .  
         [0035]    One or more flow channels  270 ,  272  are preferably formed near the upstream end of the aortic flow divider  210  to provide a fluid flow path from the upper side to the lower side of the aortic flow divider  210  when it is deployed within a patient&#39;s aorta. In the exemplary embodiment shown in FIG. 2, two flow channels  270 ,  272  are formed between a pair of inflatable tails or extensions  274 ,  276  extending from the upstream end of the wing-shaped inflatable aortic flow divider  210 . The inflatable extensions  274 ,  276  hold a web  278 , which extends between the catheter shaft  202  and the inflatable extensions  274 ,  276 , slightly away from the aortic wall to allow blood to flow through the flow channels  270 ,  272  into the aortic root.  
         [0036]    Prior to use, the aortic flow divider  210  is deflated and pressed against or wrapped around the catheter shaft  202 . This reduces the profile of the aortic catheter  200 , which facilitates insertion of the aortic catheter  200  through an aortotomy incision or introducer sheath. When it is inflated, the aortic flow divider  210  unwraps or extends from the catheter shaft  202  and assumes a somewhat flattened or gently curved shape that follows the distal curve of the catheter shaft  202 . The sealed peripheral edge  256  of the aortic flow divider  210  creates a flexible skirt around the periphery of the aortic flow divider  210  that helps to form a fluid flow seal between the aortic flow divider  210  and the aortic wall.  
         [0037]    [0037]FIG. 11 shows a flow diagram of the perfusion catheter  200  of FIG. 1 with the aortic flow divider  210  deployed within a patient&#39;s aortic arch. The patient&#39;s corporeal circulation may be perfused with blood or other fluids through the corporeal perfusion lumen  206  and the aortic arch vessels may be separately perfused through the arch perfusion lumen  204 . The multiple hole pattern of the arch perfusion ports  212  tends to diffuse the fluid flow exiting the arch perfusion ports  212 , which helps to eliminate high velocity jetting that could dislodge plaques, thrombus or other potential embolic materials. In one particularly preferred method, the patient&#39;s cerebral circulation is perfused with hypothermic oxygenated blood at approximately 28-34 C. through the arch perfusion lumen  204 , while the corporeal circulation is perfused with normothermic oxygenated blood at approximately 35-37 C. through the corporeal perfusion lumen  206 . Preferably, the ratio of the flow rates through the arch perfusion lumen  204  and the corporeal perfusion lumen  206  is maintained in the range of approximately 1:2 to 1:4, with a total flow rate of approximately 3-6 liters per minute. Studies have shown that under normothermic conditions, the flow to the arch vessels is approximately 25% of the cardiac output. This percentage drops somewhat as the brain cools to a protective hypothermic state. Maintaining the ratio within this preferred range helps to assure adequate perfusion of the cerebral circulation by providing a flow of oxygenated blood in excess of the demand by the arch vessels. This method creates a hemodynamic flow separation between the cerebral circulation and the corporeal circulation, which protects the brain by redirecting any potential emboli originating in the heart or the ascending aorta toward the corporeal circulation. In addition, excess perfusate from the arch perfusion lumen  204  flows upstream through the flow channels  270 ,  272  at the upstream end of the aortic flow divider  210  into the aortic root, which creates a washing action that directs potential emboli out of the aortic root and away from the coronary ostia. Optionally, one or more corporeal perfusion ports  220 ′ positioned on the catheter shaft  202  near the upstream end of the aortic flow divider  210  may provide additional flow into the aortic root to augment this washing action.  
         [0038]    The aortic flow divider  210  need not form a perfect seal with the walls of the aorta, nor does it need to be impermeable to emboli, in order to provide cerebral and coronary embolic protection because its primary function is not as a physical barrier to potential emboli. The hemodynamic flow separation between the cerebral circulation and the corporeal circulation provides the primary mechanism for cerebral embolic protection, while the washing action of the aortic root by the flow passing through the flow channels  270 ,  272  at the upstream end of the aortic flow divider  210  provides the primary mechanism for coronary embolic protection.  
         [0039]    FIGS.  12 - 15  show an aortic catheter  100  with a aortic flow divider  110  configured for perfusion of a patient&#39;s circulatory system. FIG. 12 shows a perspective view of the aortic catheter  100 . As in the previous example, the aortic catheter  100  is configured for central introduction into the aortic arch through an aortotomy in the ascending aorta. The aortic catheter  100  could alternatively be configured for introduction via peripheral arterial access. The aortic flow divider  110  is mounted on a distal portion of an elongated catheter shaft  102 . The catheter shaft  102  is constructed with two lumens: a perfusion lumen  104  and an inflation lumen  108 . The perfusion lumen  104  extends through the catheter shaft  102  and communicates with one or more arch perfusion ports  112 , which are located on an upper surface  114  of the aortic flow divider  110 , and with a corporeal perfusion end port  120  and/or corporeal perfusion side ports, which are located near the distal end of catheter shaft  102  and preferably downstream of and below the aortic flow divider  110 . Alternatively or in addition, one or more corporeal perfusion ports  120 ′ may be located near the upstream end of the aortic flow divider  110 . The proximal end of the perfusion lumen  104  connects to a perfusion extension tube  116  which terminates in a perfusion connector  118 , such as a barb fitting with a Luer-lock side branch or the like.  
         [0040]    The inflation lumen  108  extends through the catheter shaft  102  and connects on its distal end with an inflation port  128 , shown in FIG. 13, which communicates with the interior of the inflation chamber  130  of the aortic flow divider  110 . The proximal end of the inflation lumen  108  connects to, or is continuous with, an inflation lumen extension tube  132 , which terminates in an inflation lumen connector  134 , such as a stopcock with a Luer-lock connector or the like. A manifold  136 , which is preferably an injection molded part, provides the junction where the catheter shaft  102 , the perfusion extension tube  116  and the inflation lumen extension tube  132  join together. Preferably, the aortic catheter  100  includes an inflation indicator  138  on the inflation lumen extension tube  132 . The inflation indicator  138  is a small, low-pressure balloon that is mounted on the inflation lumen extension tube  132 , such as by heat sealing or adhesive bonding. The interior of the inflation indicator  138  is connected to the inflation lumen  108  by an inflation indicator port  140  on the inflation lumen extension tube  132 . Alternatively, the balloon-shaped inflation indicator  138  may be formed integrally with the inflation extension tube  132 . The inflation indicator  138  inflates to provide a visual indication whenever the aortic flow divider  110  is inflated.  
         [0041]    The catheter shaft  102  may be formed as a multilumen extrusion or it may be formed as a composite construction made up of individual tubes. In one particularly preferred construction, the catheter shaft  102  is constructed by joining together two individual tubes representing the perfusion lumen  104  and the inflation lumen  108 . The perfusion lumen  104  is preferably constructed as a round cross section tube, which is reinforced over at least part of its length with a wire coil  144 , as shown in FIG. 14. A molded plastic tip plug  154  may be inserted into the distal end to terminate the perfusion lumen  104 . The inflation lumen  108  is constructed as a single lumen tube, which, as noted above, may be continuous with the inflation lumen extension tube  132 . In one particularly preferred embodiment, the tube that forms the inflation lumen  108  passes through the interior of the perfusion lumen  104  in a proximal portion of the catheter shaft  102  that extends from the manifold  136  to the flow divider  110 . Optionally, this proximal portion of the catheter shaft  102  may be externally reinforced with a clear, thin-walled heat shrink tube  103  and/or a strain relief tube may be provided to reinforce the junction between the manifold  136  and the catheter shaft  102 . One or more arch perfusion ports  112  are cut or drilled through the wall of the perfusion lumen  104  in the distal portion catheter shaft  102 .  
         [0042]    A gentle S-shaped curve is set into the catheter shaft  102  by placing the catheter shaft  102  on a curved mandrel and heating it. The distal portion of the catheter shaft  102  where the aortic flow divider  110  will be mounted is given a curve that approximates the internal curvature of a human aortic arch. A depth stop  168  is attached to the exterior of the catheter shaft  102  slightly proximal to where the aortic flow divider  110  will be mounted. Preferably, the depth stop  168  is mounted slightly obliquely on the catheter shaft  102 , as shown in FIG. 14, so that it will lie flat against the outer wall of the aorta when the curved catheter shaft  102  is inserted through an aortotomy incision into the ascending aorta. Preferably, an orientation stripe  101  or other mark is printed on the exterior of the catheter shaft  102  to indicate the orientation of the aortic flow divider  110  once it has been inserted through the aortotomy incision into the ascending aorta.  
         [0043]    [0043]FIG. 13 shows a top view of a distal end portion of the aortic catheter  100  of FIG. 12 showing the aortic flow divider  110  in a deflated condition. The aortic flow divider  110  has an upper wall  114  and a lower wall  122  that enclose an inflation chamber  130 . The upper wall  114  and lower wall  122  of the aortic flow divider  110  are preferably constructed of a first and second sheet of plastic film that are joined to one another around their peripheral edges  156  and at one or more interior locations  158 , for example by heat sealing or adhesive bonding. Suitable materials for the upper wall  114  and lower wall  122  of the aortic flow divider  110  include, but are not limited to, polymers, elastomers, thermoplastics, polyvinylchloride, polyurethane, polyethylene, polyamides, polyesters, silicone, latex, and alloys or copolymers, and reinforced composites thereof. The plastic film that makes up the upper wall  114  and lower wall  122  may have the same or different thicknesses. For example, the upper wall  114  may be made of a thinner plastic film than the lower wall  122 .  
         [0044]    The aortic flow divider  110  is generally an elongated oval shape that is sized to fit within the lumen of a patient&#39;s aortic arch. In one particularly preferred embodiment, the upper wall  114  of the aortic flow divider  110  is slightly larger in length and width than the lower wall  122 . When the peripheral edges  156  of the upper wall  114  and lower wall  122  are heat sealed together, this creates a pair of longitudinal folds or wrinkles  160 ,  162  and at least one lateral fold or wrinkle  164  in the upper wall  114  when the aortic flow divider  110  is deflated, as seen in the top view in FIG. 13. These folds or wrinkles  160 ,  162 ,  164  create flow channels that assist the aortic flow divider  110  to deflate fully under applied vacuum.  
         [0045]    The interior seals  158  of the aortic flow divider  110  are located so that they will cover the arch perfusion ports  112  in the distal portion of the catheter shaft  102 . Holes  166  are cut through the interior seals  158  to coincide with each of the arch perfusion ports  112 . Once the aortic flow divider  110  is formed, it is adhesively bonded and/or heat bonded to the distal portion of the catheter shaft  102  with the holes  166  positioned over the arch perfusion ports  112 . Alternatively, the holes  166  through the interior seals  158  and the arch perfusion ports  112  may be drilled simultaneously after the aortic flow divider  110  has been bonded to the catheter shaft  102  to assure precise alignment. The distal end of the inflation lumen  108  communicates with the inflation chamber  130  through the inflation port  128 .  
         [0046]    One or more flow channels  170 ,  172  are preferably formed near the upstream end of the aortic flow divider  110  to provide a fluid flow path from the upper side to the lower side of the aortic flow divider  110  when it is deployed within a patient&#39;s aorta. In the exemplary embodiment shown in FIG. 13, two flow channels  170 ,  172  are formed between a pair of inflatable tails or extensions  174 ,  176  extending from the upstream end of the wing-shaped inflatable aortic flow divider  110 . The inflatable extensions  174 ,  176  hold a web  178  of plastic film, which extends between the catheter shaft  102  and the inflatable extensions  174 ,  176 , slightly away from the aortic wall to allow blood to flow through the flow channels  170 ,  172  into the aortic root.  
         [0047]    [0047]FIG. 14 shows a side view of the aortic catheter  100  with the aortic flow divider  110  in a deflated condition positioned alongside an insertable obturator  105 . The obturator  105  is preferably configured as a flexible rod or tube having a length slightly longer than the overall length of the catheter  100  and a diameter sized to substantially fill the perfusion lumen  104  of the catheter  100 . Suitable materials for the obturator  105  include, but are not limited to, polymers, elastomers, thermoplastics, polyvinylchloride, polyurethane, polyethylene, polyamides, polyesters, silicone, latex, and alloys or copolymers, and reinforced composites thereof. The obturator  105  may be inserted into the perfusion lumen  104  of the aortic catheter  100  prior to use in order to reduce backbleeding through the perfusion lumen  104  during insertion of the catheter  100  into the arterial system.  
         [0048]    Prior to use, the aortic flow divider  110  is deflated and pressed against or wrapped around the catheter shaft  102 . This reduces the profile of the aortic catheter  100 , which facilitates insertion of the aortic catheter  100  through an aortotomy incision or introducer sheath. When it is inflated, the aortic flow divider  110  unwraps or extends from the catheter shaft  102  and assumes a somewhat flattened or gently curved shape that follows the distal curve of the catheter shaft  102 . The sealed peripheral edge  156  of the aortic flow divider  110  creates a flexible skirt around the periphery of the aortic flow divider  110  that helps to form a fluid flow seal between the aortic flow divider  110  and the aortic wall.  
         [0049]    [0049]FIG. 15 shows a flow diagram of the perfusion catheter  100  of FIG. 12 with the aortic flow divider  110  deployed within a patient&#39;s aortic arch. The patient&#39;s circulation may be perfused with oxygenated blood or other fluids through the perfusion lumen  104 . Flow from the arch perfusion ports  112  supplies the cerebral circulation, while flow from the corporeal perfusion port  120  supplies the corporeal circulation. The multiple hole pattern of the arch perfusion ports  112  tends to diffuse the fluid flow exiting the arch perfusion ports  112 , which helps to eliminate high velocity jetting that could dislodge plaques, thrombus or other potential embolic materials. The patient may be perfused with hypothermic oxygenated blood at approximately 28-34 C. or with normothermic oxygenated blood at approximately 35-37 C. Preferably, the perfusion catheter  100  is configured to provide a flow ratio of approximately 1:2 to 1:4 between the arch perfusion ports  112  and the corporeal perfusion port  120 , with a total flow rate of approximately 3-6 liters per minute. Studies have shown that under normothermic conditions, the flow to the arch vessels is approximately 25% of the cardiac output. This percentage drops somewhat as the brain cools to a protective hypothermic state. Maintaining the ratio within this preferred range helps to assure adequate perfusion of the cerebral circulation by providing a flow of oxygenated blood in excess of the demand by the arch vessels. This method creates a hemodynamic flow separation between the cerebral circulation and the corporeal circulation, which protects the brain by redirecting any potential emboli originating in the heart or the ascending aorta toward the corporeal circulation. In addition, excess perfusate from the arch perfusion lumen  104  flows upstream through the flow channels  170 ,  172  at the upstream end of the aortic flow divider  110  into the aortic root, which creates a washing action that directs potential emboli out of the aortic root and away from the coronary ostia. Optionally, one or more corporeal perfusion ports  120 ′ positioned on the catheter shaft  102  near the upstream end of the aortic flow divider  110  may provide additional flow into the aortic root to augment this washing action.  
         [0050]    As noted above, the aortic flow divider  110  need not form a perfect seal with the walls of the aorta, nor does it need to be impermeable to emboli, in order to provide cerebral and coronary embolic protection because its primary function is not as a physical barrier to potential emboli. The hemodynamic flow separation between the cerebral circulation and the corporeal circulation provides the primary mechanism for cerebral embolic protection, while the washing action of the aortic root by the flow passing through the flow channels  170 ,  172  at the upstream end of the aortic flow divider  110  provides the primary mechanism for coronary embolic protection.  
         [0051]    [0051]FIG. 16 shows a flow diagram of an exemplary embodiment of a perfusion catheter  200  with an aortic flow divider  210  deployed within a patient&#39;s aortic arch via a peripheral artery insertion site. The peripheral entry aortic perfusion catheter  200  of FIG. 16 may be configured with one or two perfusion lumens within the catheter shaft  202 .  
         [0052]    While the present invention has been described herein with respect to the exemplary embodiments and the best mode for practicing the invention, it will be apparent to one of ordinary skill in the art that many modifications, improvements and subcombinations of the various embodiments, adaptations and variations can be made to the invention without departing from the spirit and scope thereof.