Abstract:
A system and methods are described for performing catheter based procedures on high risk patients that mitigate the risk to the patient and extend the acceptable time window for response when emergencies or complications arise. The system is useful for stopped heart catheter procedures or as a safety backup in beating heart catheter procedures and is compatible with concurrent or sequential surgical interventions. The system combines a therapeutic or diagnostic catheter subsystem with a selective aortic perfusion and cardiopulmonary bypass subsystem. The catheter subsystem may include catheters for angioplasty, stent delivery, atherectomy, valvuloplasty or other diagnostic or therapeutic procedures. The selective aortic perfusion and cardiopulmonary bypass subsystem generally includes catheters and/or cannulas for draining blood from the patient&#39;s venous or arterial system, a perfusion pump, a blood oxygenator, at least one blood heat exchanger and catheters and/or cannulas for perfusing oxygenated blood into the patient&#39;s arterial system. The arterial perfusion catheters and/or cannulas are constructed with an upstream flow control member located in the patient&#39;s ascending aorta and a downstream flow control member located in the patient&#39;s descending aorta. The external flow control members may take the form of inflatable occlusion balloons and/or selectively deployable external catheter flow control valves. The external flow control members may be mounted on a single elongated catheter or cannula shaft or they may be mounted on separate catheter or cannula shafts for independent placement and deployment.

Description:
The present invention claims benefit and is a continuation-in-part application of application Ser. No. 09/060,412, filed Apr. 14, 1998, now U.S. Pat. No. 6,110,145, which is a continuation-in-part of application Ser. No. 08/632,883, filed Apr. 16, 1996 and PCT/US97/06243, filed Oct. 23, 1997, now U.S. Pat. No. 5,738,649 and claims benefit of U.S. Provisional Application No. 60/098,724, filed Sep. 1, 1998, now abandoned. 
    
    
     FIELD OF INVENTION 
     The present invention relates generally to cardiovascular catheters and also to circulatory support systems. More particularly, it relates to a system and method for performing catheter based medical procedures, such as balloon angioplasty, stent placement, atherectomy, valvuloplasty and other therapeutic procedures, with protective circulatory support in order to minimize the risk to the patient from such procedures. The system and methods of the present invention serve to expand the patient population treatable by catheter based procedures to include patients who might otherwise require open chest surgery with cardiopulmonary bypass and also to high risk patients who might not be acceptable candidates for these surgical alternatives. 
     BACKGROUND OF THE INVENTION 
     Many catheter based diagnostic and therapeutic procedures have been developed in the areas of interventional cardiology, interventional radiology, interventional neuroradiology and electrophysiology. Examples of such procedures include balloon angioplasty, stent placement, atherectomy and valvuloplasty. These and many other catheter based diagnostic and therapeutic procedures can benefit from the system and methods of the present invention, particularly in high risk patients. 
     Balloon angioplasty is a procedure in which a small, cylindrical balloon is mounted on an elongated catheter which is inserted into a stenosis or a narrowing in a blood vessel and inflated to dilate the stenosis and improve blood flow. Balloon angioplasty can be applied to coronary arteries, carotid arteries and peripheral arteries, as well as other body passages. Patents which describe apparatus and methods for performing balloon angioplasty include U.S. Pat. Nos. 4,195,637; 4,323,071; 4,545,390; 4,545,390; 4,538,622; 5,055,024; 4,490,421; 4,616,653; 5,133,364; 5,060,660; 5,031,636; 4,922,923; 4,917,103; 4,875,489; 4,827,941; 4,762,129; 4,988,356; 4;748;982; 5,040,548 and 5,061,2,73. The specifications of these patents and all other patents and patent applications mentioned herein are hereby incorporated by reference in their entirety. 
     Valvuloplasty is a closely related procedure in which a somewhat larger balloon or balloons are inserted into a stenosis in a heart valve and inflated to open the stenosis and improve blood flow through the valve. Valvuloplasty can be applied to the aortic valve, mitral valve, tricuspid valve or pulmonic valve. Patents which describe apparatus and methods for performing valvuloplasty include U.S. Pat. Nos. 4,787,388; 4,796,629; 4,909,252; 5,295,958. 
     Atherectomy is an alternative procedure to balloon angioplasty in which, rather than simply dilating the stenosis, some or all of the stenotic material is removed to debulk the stenosis and improve blood flow. Atherectomy includes both rotational atherectomy in which stenotic material is removed symmetrically about the catheter and directional atherectomy in which stenotic material is selectively removed from certain parts of the blood vessel. Patents which describe apparatus and methods for performing atherectomy include. U.S. Pat. Nos. 4,323,071; 5,071,425; 4,781,186; RE 33,569; 4,290,427; 4,315,511; 4,574,781; 4,621,636; 4,890,611; 5,368,603; 3,730,183; 5,071,424; 5,156,610; 5,282,484; 5,211,651; 5,267,955; 5,195,956; 5,178,625; 4,589,412; 4,854,325; 4,883,460; 4,273,128. 
     Stent placement, is a procedure often very closely associated with balloon angioplasty and also sometimes with atherectomy. Vascular stents, also known as endovascular prostheses, are small, generally cylindrical, metallic or polymeric scaffolds that are implanted within the lumen of a blood vessel to maintain patency of the lumen. Elective stent placement may be done as an adjunct to balloon angioplasty or atherectomy or emergency stent placement may be done in the case of a failed angoplas or atherectoiny. Stents can be applied to coronary arteries, carotid arteries and peripheral arteries, as well as other body passages. Stent grafts or covered stents resemble standard vascular stents with the addition of a prosthetic vascular wall over the metallic or polymeric scaffold of the stent. Patents which describe apparatus and methods for performing stent placement include. U.S. Pat. Nos. 5,041,126; 4,856516; 5,037,392; 5,683,452; 5,578,072; 5,571,171; 5,522,880; 5,360,443; 5,102,417; 4,776,337; 4,739,762; 4,733,665; 55674,278; 5,782,855; 5,780,807; 5,766,710; 5,766,239; 5,766,238; 5,759,192; 5,738,674; 5,735,893; 5,733,330; 5,728,158; 5,725,572; 5,725,549; 5,707,385; 5,700,286; 5,681,346; 5,649,977; 5,649,952; 5,637,113; 5,632,840; 5,629,077; 5,618,299; 5,607,444; 5,605,696; 5,603,721; 5,593,434; 5,591,197; 5,569,295; 5,556,413; 5,546,646; 5;514,154; 5,507,768; 5,498,240; 5,476,505; 5,458,615; 5,458,605; 5,456,667; 5,443,500; 5,443,458; 5,441,515; 5,437,083; 5,423,885; 5,421,955; 5,415,637; 5,409,495; 5,391,172; 5,360,401; 5,344,426; 5,242,399; 5,158,548. 
     Electrophysiology diagnostic studies and therapeutic ablation procedures are used for diagnosis and treatment of various cardiac arrhythmias. Patents that describe apparatus and methods for performing electrophysiology procedures include U.S. Pat. Nos. 4,699,147; 5,327,889; 4,960,134; 5,140,987; 4,522,212; 4,660,571; 4,664,120; 5,125,896; 5,104,393. 
     Other catheter based procedures will also benefit from the system and methods of the present invention, particularly in high risk patients. For example: transmyocardial revascularization, U.S. Pat. Nos. 4,658,817; 5,125,924; 5,125,926, patent ductus arteriosus closure, septal defect repair, U.S. Pat. Nos. 3,874,388; 4,874,089, intravascular ultrasonic imaging, U.S. Pat. Nos. 5,000,185; 4,794,931; 5,029,588; 4,024,234; 4,917,097; 5,167,233; 5,368,037; 5,190,046; WO 94/16625, laser angioplasty or ablation, U.S. Pat. Nos. 5,354,294; 5,366,456; 5,163,935; 4,740,047; 5,242,438; 5,147,353; 5,242,437; 5,188,634; 5,026,366; 4,788,975. 
     The system and methods of the present invention find particular use in performing catheter based medical procedures, such as balloon angioplasty, stent placement, atherectomy, valvuloplasty and other therapeutic procedures, on high risk patients. High risk patients in this context include extremely young or extremely elderly patients and patients whose cardiopulmonary functions are severely compromised. 
     In addition to the above examples, patients with severe cardiovascular disease or other complicating factors, such as patients requiring balloon angioplasty, stent placement or atherectomy in highly critical portions of the vasculature will particularly benefit from these procedures. Examples of highly critical portions of the vasculature may include: lesions in the ostia of the coronary arteries, the left main coronary artery, diseased saphenous vein grafts and totally occluded coronary arteries or the carotid arteries. 
     Because of the risks to the patient, the aforementioned catheter procedures are usually performed while a surgical backup team stands by on call with a surgical suite reserved for emergency surgery in the event that the procedure fails or if dangerous complications arise. This gives rise to two specific problems, surgical backup may not always be logistically possible and surgical backup is costly. One example of where surgical backup is not logistically possible, is when the catheter procedure is being performed in an emergency situation. 
     Surgical backup is also a significant economic burden for the patient, the hospital and the entire medical system. The timing for emergency surgery is very critical, although the surgical backup team only needs to be relied upon in a very small percentage of cases, it is necessary to have the surgical team and the operating room ready immediately. In particular, where a failed procedure results in severe complications, such as cardiac arrest, myocardial infarction or cerebral ischemia or embolization, there is only a narrow window of response time available to perform emergency surgery in order to save the patient. 
     Therefore, because of the conflicting pressures of economics and of patient safety, it would be extremely desirable to reduce the reliance on surgical backup for high risk catheter based procedures. The present invention is intended to provide a margin of protection that mitigates the risk to the patient and extends the acceptable time window for response when emergencies or complications arise. 
     Various strategies have been proposed to mitigate the danger to patients during high risk catheter procedures. These proposed strategies have include perfusion balloon catheters, intra-aortic balloon pumps, percutaneous or femoral-femoral cardiopulmonary bypass, retrograde coronary perfusion, and single-balloon intra-aortic occlusion catheters for cardioplegic arrest. None of these approaches provide all of the benefits of the present invention. 
     Perfusion balloon catheters, U.S. Pat. Nos. 5,573,508; 5,573,509; 5,344,402, are angioplasty catheters which have been adapted to provide blood flow downstream of the dilatation balloon to prevent ischemia of the myocardium during prolonged inflation of the balloon. This approach protects only the myocardium at risk of infarction downstream from the dilatation site. It does not provide global circulatory protection or selective cerebral protection in the event of low cardiac output or cardiac arrest. It also does not provide for elective cardiac arrest or a transition to cardiopulmonary bypass in the event that surgical intervention becomes necessary. Perfuision balloon catheters can be used in conjunction with the system and methods of the present invention. 
     Intra-aortic balloon pumps (IAPB) are balloon catheters that provide counterpulsation to reduce the cardiac pumping load and to augment coronary artery circulation. An IAPB only assists the beating heart in providing circulation and therefore would not provide global circulatory protection or selective cerebral protection in the event of cardiac arrest. An IAPB also does not provide for elective cardiac arrest or a transition to full cardiopulmonary bypass in the event that surgical intervention becomes necessary. 
     Percutaneous or femoral-femoral cardiopulmonary bypass, U.S. Pat. Nos. 3,513,845; 4,540,399; 5,0119469 is an approach to cardiopulmonary bypass (CPB) which uses peripherally inserted arterial and venous cannulas to avoid the necessity of a median sternotomy. This circulatory support method has been suggested for use in high risk angioplasty cases. However, this method affords no provision for safe, elective (e.g. cardioplegic) cardiac arrest, nor does it provide for prioritized cerebral protection. 
     Retrograde coronary perfusion or coronary retroperfusion (e.g. U.S. Pat. Nos. 5,451,207; 5,451,207; 5,655,548; 5,597,377; 5,533,957; 5,423,745; 5,401,244; 5,395,331; 5,324,260; 5,290,231; 5,059,167; 5,033,998; 5,024,668; 5,011,468; 4,934,996; 4,927,412; 4,917,667; 4,865,581; 4,850,969; 4,648,384; 4,459,977; 4,290,428) has been suggested for the treatment of myocardial ischemia, for myocardial protection during high risk catheter procedures and for administering cardioplegic arrest. For example, U.S. Pat. No. 5,451,207 describes the use of retrograde coronary perfusion for myocardial protection during a coronary atherectomy procedure. Retrograde coronary perfusion, however, requires additional cannulation in order to make the transition to cardiopulmonary bypass and it does not provide prioritized cerebral protection. 
     Single-balloon intra-aortic occlusion catheters, e.g. WO 96/30072, have been suggested for myocardial protection and for emergency or elective cardioplegic arrest during high risk catheter procedures. Single-balloon intra-aortic occlusion catheters of this type do not provide prioritized cerebral protection. U.S. Pat. No. 5,695,457 describes a system of coronary isolation catheters as a substitute for the single-balloon intra-aortic occlusion catheter for cardioplegia delivery and for use in high risk angiopiasty and other catheter procedures. This system also does not provide prioritized cerebral protection. 
     Another related technology involves cardiopulmonary support by selective aortic perfusion. U.S. Pat. Nos. 5,308,320, 5,383,854, 5,820,593 and 5,906,588 by Peter Safar, S. William Stezoski, and Miroslav Klain describe catheters that segment the aorta to perform differential perfusion. Other U.S. patent applications which address the concept of selective aortic perfusion include commonly owned, copending patent applications 08/909,293, filed Aug. 11, 1997; and 09/152,589 filed Aug. 11, 1998 to Safar et al. 
     Furthermore, U.S. Pat. Nos. 5,738,649, 5,827,237, 5,833,671; and commonly owned, copending patent applications 09/060,412, filed Apr. 14, 1998 by John A. Macoviak; and 08/665,635, filed Jun. 17, 1996; by John A. Macoviak and Michael Ross; and 60/067,945, filed Dec. 8, 1997, by Bresnahan et al. and 60/084,835, filed Apr. 25, 1997 by Macoviak et al. describe circulatory support systems and methods of use for isolated segmental perfusion. Perfusion shunt devices and deflectors for perfusing an isolated organ system while the beating heart supplies the remainder of the circulatory system are described in commonly owned, copending patent application 09/212,580, filed Dec. 14, 1998 and 60/116,836, filed Oct. 1, 1998 by Macoviak et al. In addition, commonly owned, copending patent application 09/306,555, filed May 6, 1999 by Macoviak et al. describes a circulatory support system and method of use for isolated segmental perfuision. These patent applications and all other patents referred to herein are hereby incorporated by reference in their entirety. Selective perfusion can be used to prioritize the flow of oxygenated blood or other protective fluids to the various organ systems, with different temperatures or compositions, for achieving optimal preservation of all organ systems within the body. 
     SUMMARY OF THE INVENTION 
     In keeping with the foregoing discussion, the present invention provides a system and methods for performing catheter based procedures on high risk patients that mitigate the risk to the patient and extend the acceptable time window for response when emergencies or complications arise. The system is useful in a number of operating modes, including: stopped heart catheter procedures, concurrent surgical interventions, sequential surgical interventions, catheter based interventions and as a safety backup or bail out system in beating heart catheter procedures. The system provides cardiopulmonary support for the patient&#39;s circulatory system and prioritized protection for the patient&#39;s cerebral and coronary circulation. The system, when used according to the methods of the present invention, allows a patient to be placed in varying degrees of suspended animation during the catheter procedure. Furthermore, when emergencies or complications arise, implementation of these procedures are intended to protect the patient&#39;s critical organ systems and to extend the safe period of time to initiate a surgical intervention. 
     The system combines a therapeutic or diagnostic catheter subsystem, which may take one of many known forms, with a selective aortic perfusion and cardiopulmonary bypass subsystem. The therapeutic or diagnostic catheter subsystem may take the form of an angioplasty subsystem, typically an angioplasty balloon catheter, a guiding catheter and a guidewire; a stent delivery subsystem, typically a stent delivery catheter, a stent, a guiding catheter and a guidewire; an atherectomy subsystem, typically an atherectomy catheter, a guiding catheter and a guidewire; a valvuloplasty subsystem, typically a valvuloplasty balloon catheter and a guidewire; or other known diagnostic or therapeutic catheter systems. The selective aortic perfusion and cardiopulmonary bypass subsystem generally includes catheters and/or cannulas for draining blood from the patient&#39;s venous or arterial system, a perfusion pump, a blood oxygenator, at least one blood heatexchanger and catheters and/or cannulas for perfusing oxygenated blood into the patient&#39;s arterial system. The arterial perfusion catheters and/or cannulas are especially configured to perform aortic segmentation and selective perfusion of the patient&#39;s circulatory system. 
     In order to accomplish aortic segmentation, the arterial perfusion catheters and/or cannulas are constructed with at least a first external flow control member and a second external flow control member. Additional external flow control members may be included if further segmentation of the circulatory system is desired. The external flow control members may take the form of inflatable occlusion balloons and/or selectively deployable external catheter flow control valves. The external flow control members may be mounted on a single elongated catheter or cannula shaft or they may be mounted on separate catheter or cannula shafts for independent placement and deployment. 
     When the arterial perfusion catheters and/or cannulas are deployed, the first external flow control member is positioned in the patient&#39;s ascending aorta between the coronary arteries and the brachiocephalic artery, and the second external flow control member is positioned in the patient&#39;s descending aorta downstream of the aortic arch. The external flow control members are used to control or to occlude fluid flow through the lumenof the aorta so that the aorta is divided into an ascending aorta or coronary artery segment, an aortic arch or cerebral blood flow segment and a descending aorta or corporeal blood flow segment. Each of these segments is perfusable separately or in combination. This may be accomplished by perfusion lumens within the same catheter or cannula shaft as the external flow control members are mounted on and/or through separate perfusion cannulas that are inserted into each segment. Each of the segments may be perfused with oxygenated blood and/or other fluids having a composition and/or temperature chosen for optimal preservation of the organ systems fed by the blood vessels branching from the segments. 
     In one particular embodiment of the system, the first and second external flow control members are mounted off the upstream and downstream ends of a perfusion shunt lumen, which allows blood flow from the heart to flow past the aortic arch without entering the arch vessels. An arch perfusion lumen allows selective perfusion of the arch vessels. 
     In some embodiments of the system, one or more of the components of the therapeutic catheter subsystem may be integrated with the components of the selective aortic perfusion and cardiopulmonary bypass subsystem to create a dual purpose device. For example, an angioplasty or atherectomy guiding catheter may be combined with two external flow control members to create a combined guiding catheter and aortic segmentation catheter. 
     When the system is used for performing stopped heart catheter procedures on a patient, cardiopulmonary bypass is established and the heart is stopped by elective cardiac arrest, for example by cardioplegic or hypothermic arrest. While the heart is stopped, each segment of the circulatory system is perfused with an, appropriate fluid to optimize preservation of the organs within each segment. The catheters of the therapeutic catheter subsystem are introduced either coaxially or in parallel with the aortic perfusion catheters or cannulas and the catheter procedure is performed while the heart is stopped. After the catheter procedure is complete, the heart is restarted and the patient is weaned off of bypass. Performing the catheter procedure while the heart is stopped significantly mitigates the risk to the patient from the catheter procedure or its possible complications. 
     When the system is used as a safety backup or bail out system while performing beating heart catheter procedures, the patient is cannulated and partial cardiopulmonary bypass may be initiated for circulatory support, but full cardiopulmonary bypass is not initiated. The catheters of the therapeutic catheter subsystem are introduced either coaxially or in parallel with the aortic perfusion catheters or cannulas and the catheter procedure is performed in the normal manner while the heart is still beating. If the catheter procedure is successful and there are no complications, the patient is extubated at the end of the procedure and sent to the recovery room. However, if emergencies or complications arise during the catheter procedure, full cardiopulmonary bypass can be established immediately by simply stepping up the flow rate of the perfusion pump. In addition, selective aortic perfusion can be performed by deploying the external flow control members enabling the segmentation of the aorta whereby each segment can be perfused with a separate protective fluid. Through this method, the patient can be placed in varying degrees of suspended animation protecting the affected organ systems until an emergency surgical intervention can be performed. The different degrees of suspended animation include: partial bypass for circulatory support, full cardiopulmonary bypass and elective cardiac arrest, neuroplegic arrest, with or without elective cardiac arrest, and complete hypothermic circulatory arrest. The patient can be kept in the selected degree of suspended animation while the surgical team is assembled and while the operating room is being prepared or while the patient is being transferred to another facility with the necessary surgical resources. 
     The system may also be used for performing catheter procedures on a patient in conjunction with elective surgical interventions. For example angioplasty, stenting or atherectomy can be performed in conjunction with coronary artery bypass or cardiac valve replacement surgery. The catheter procedures may be performed concurrently with the surgical interventions while the heart is stopped or they can be performed sequentially before or after the surgical interventions while the heart is stoppe,d or while it is beating. If the catheter procedure is performed while the heart is beating, the selective aortic perfusion and cardiopulmonary bypass subsystem will be used as a safety backup system during the catheter procedure, as described above. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A shows a first embodiment of the system for performing catheter based medical procedures with protective circulatory support having a dual-balloon selective arterial perfusion cannula. 
     FIG. 1B is a cross section view of the catheter shaft of the aortic catheter of FIG.  1 . 
     FIG. 2 shows a second embodiment of the system for performing catheter based medical procedures with protective circulatory support having a dual-balloon selective arterial perfusion cannula and a contralateral therapeutic catheter subsystem. 
     FIG. 3A shows a third embodiment of the system for performing catheter based medical procedures with protective circulatory support having a selective arterial perfusion cannula with first and second selectively deployable external catheter flow control valves. 
     FIG. 3B is a cross section view of the catheter shaft of the aortic catheter of  3 A. 
     FIG. 4 shows a fourth embodiment of the system for performing catheter procedures with a perfusion shunt device for selective perfusion of a patient&#39;s cerebral circulation and upper extremities, while the beating heart supplies the viscera and lower extremities with blood. 
     FIG. 5A shows an alternative embodiment of the system for performing catheter procedures, wherein the therapeutic catheter subsystem includes a guiding catheter having first and second external flow control members in the form of inflatable occlusion balloons or selectively deployable external catheter flow control valves. 
     FIG. 5B is a cross section view of the catheter shaft of the aortic catheter of FIG.  5 A. 
     FIG. 6 shows another alternative embodiment of the system for performing catheter procedures with a low profile dual-balloon occlusion catheter having a first and a second external flow control member in the form of inflatable occlusion balloons or selectively deployable external catheter flow control valves. 
     FIG. 7 shows another alternative embodiment of the catheter system of the present invention with a first and second perfusion cannula configured for delivering a therapeutic catheter subsystem and capable of selective perfusion to separate organ systems. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the figures where like reference numbers refer to similar components or features, FIG. 1A shows a first exemplary embodiment of the system for performing catheter based medical procedures with protective circulatory support in high risk patients. The system of FIG. 1A uses a dual-balloon selective arterial perfusion cannula similar to those described in U.S. Pat Nos. 5,308,320, 5,383,854, 5,820,593 and 5,906,588 and in commonly owned, copending patent applications 08/909,293, 09/152,589 and 09/205,753, which have previously been incorporated by reference. The dual balloon selective arterial perfusion cannula is modified for this application by making the distal perfusion lumen with sufficient internal diameter to accommodate the catheters of the therapeutic catheter subsystem. 
     The system of FIG. 1A includes a venous cannula  106  that is inserted into a large vein of the patient&#39;s circulatory system, such as the inferior or superior vena cava, the femoral vein or the jugular vein, and/or into the right ventricle. The venous cannula  106  mnay be inserted through a peripheral venous access, such as through the femoral vein or the jugular vein, or through a central access into the inferior or superior vena cayva or the right ventricle. The venous cannula  106  has at least one drainage lumen for draining venous blood from the patient. The drainage lumen of the venous cannula  106  is connected by way of connector tubing to a cardiopulmonary support system  114 . The cardiopulmonary support system  114  typically includes a venous blood reservoir, a blood oxygenator, a perfusion pump and at least one blood heat exchanger and a cardioplegia source. The output of the cardiopulmonary support system  114  is connected to the double-balloon selective aortic perfusion cannula  100 . 
     The dual-balloon, selective arterial perfusion cannula  100  is configured for retrograde introduction into the patient&#39;s aorta via a peripheral arterial access point, such as the femoral artery. Referring to FIG. 1B the dual-balloon, selective arternal perfusion cannula  100  has a tubular shaft  102  that includes an arch perfusion lumen  126 , a cardioplegia or distal perfusion lumen  153 , upstream and downstream balloon inflation luimens  158  and  159 , alternatively one lumen may be used, and optionally, a corporeal perfusion lumen  151  and a root pressure lumen  179 . A first, upstream occlusion balloon  104  or other expandable occlusion member is mounted on the tubular shaft  102  so that it is positioned in the ascending aorta between the coronary arteries and the right brachiocephalic artery. A second, downstream occlusion balloon  101  or other expandable occlusion member is mounted on the tubular shaft  102  so that it is positioned in the descending aorta downstream of the left subclavian artery. The optional corporeal perfusion lumen  151  extends through the tubular shaft  102  from a corporeal perfusion fitting  121  on the proximal end of the catheter  100  to one or more corporeal perfusion ports  130  on the tubular shaft  102  proximal to the downstream occlusion balloon  101 . 
     If the catheter  100  is constructed without the optional corporeal perfusion lumen  151 , corporeal perfusion can be provided through a coaxial, collateral or contralateral perfusion cannula. The arch perfusion lumen  126  extends through the tubular shaft  102  from an arch perfusion fitting  122  on the proximal end of the catheter  100  to one or more arch perfusion ports  103  on the tubular shaft  102  between the upstream occlusion balloon  104  and the downstream occlusion balloon  101 . 
     The cardioplegia or distal perfusion lumen  153  extends through the tubular shaft  102  from a cardioplegia fitting  132  on the proximal end of the catheter  100  to one or more cardioplegia ports  116  on the tubular shaft  102  distal to the upstream occlusion balloon  104 . The cardioplegia fitting also includes a Touhy-Borst compression fitting  115  or other suitable hemostasis valve configured for receiving a second medical instrument and creating a fluid tight seal. The distal perfusion lumen  153  is made with an, internal diameter sufficient to accommodate the catheters of the therapeutic catheter subsystem as well as fluid delivery. Optionally, the arterial catheter may also include a root pressure lumen  179  that extends through the tubular shaft  102  from a pressure fitting  169  on the proximal end of the catheter  102  to a pressure port  189  on the tubular shaft distal to the upstream occlusion balloon. A common balloon inflation lumen or separate balloon inflation lumens  158  and  159  extend through the tubular shaft from one or more balloon inflation fittings  128  and  129  on the proximal end of the cannula to balloon inflation ports  155  within the upstream occlusion balloon  104  and the downstream occlusion balloon  101 . 
     The system includes a therapeutic catheter subsystem, which may take one of many known forms. In this illustrative embodiment, the system is shown with a coronary angioplasty subsystem, including an angioplasty balloon catheter  123 , a guiding catheter  105  and a guidewire  190 . In similar exemplary embodiments, the, system may include a coronary stent placement subsystem, a coronary atherectomy subsystem using a directional or rotational atherectomy catheter, an aortic or mitral valvuloplasty subsystem or other known therapeutic catheter system. 
     Angioplasty guiding catheters are typically made with an external diameter between 6 and 9 French (approximately 2-3 mm outside diameter), whereas atherectomy guiding catheters are typically made with an external diameter between 6 and 12 French (approximately 2-4 mm outside diameter). The distal perfusion lumen  153  of the dual-balloon, selective arterial perfusion cannula  100  should be made with an internal diameter sufficient to accommodate the chosen guiding catheter with additional clearance for easy insertion and manipulation of the guiding catheter. In addition, the distal perfusion lumen  153  may be lined with a lubricious material, such as a fluoropolymer like PTFE, to facilitate. insertion and manipulation of the guiding catheter. Alternatively, the guiding catheter of the angioplasty subsystem may be integrated into the dual-balloon, selective arterial perfusion cannula  100  to create a combined dual-purpose device. A Y-fitting  115  with a hemostasis valve or Touhy-Borst compression fitting is provided at the proximal end of the distal perfusion lumen  153  of the dual-balloon, selective arterial perfusion cannula  100  to allow insertion and withdrawal of the therapeutic catheter subsystem without excessive bleeding or leaking of perfusate. 
     FIG. 2 shows a second exemplary embodiment of the system for performing catheter based medical procedures with protective circulatory support in high risk patients. The system of FIG. 2 uses a dual-balloon selective arterial perfusion cannula  200  similar in many ways to the cannula  100  described above in connection with FIG.  1 A. However, in this embodiment the therapeutic catheter subsystem is inserted into the contralateral femoral artery and advanced through the aorta in parallel with the dual-balloon selective arterial perfusion cannula  200 . Possible modifications to the dual-balloon, selective arterial perfusion cannula  100  of FIG. 1A for this embodiment of the system include elimination of the Y-fitting and possible reduction of the internal diameter of the distal perfusion lumen since it is not required to accommodate the catheters of the therapeutic catheter subsystem. 
     Again, the therapeutic catheter subsystem may take one of many possible forms. For example, when used in combination with a coronary angioplasty, stent placement or atherectomy subsystem, the guiding catheter  250  is advanced through the aorta parallel with the dual-balloon selective arterial perfusion cannula  200 . If the system is being used as a safety backup system in beating heart catheter procedures, the first  204  and second aortic occlusion balloons  205  of the dual-balloon selective arterial perfusion cannula need not be inflated initially. If it is deemed necessary to make a transition to a stopped heart procedure, either electively or in the event of an emergency, the first  204  and second  205  aortic occlusion balloons are inflated to occlude the aortic lumen. The guiding catheter  250  is sealed between the inflated second balloon  205  and the aortic wall. This does not interfere with the ability of the second occlusion balloon  205  to segment the aortic lumen. 
     This embodiment of the system is particularly useful for procedures, such as carotid angioplasty and carotid stent placement, where the therapeutic catheter subsystem is not required to extend all the way through the dual-balloon selective arterial perfusion cannula  200 . FIG. 2 illustrates the use of the system with a carotid stent placement subsystem, including a stent placement catheter  240 , a stent  230 , a guiding catheter  250  and a guidewire  260 . The guiding catheter  250  parallels the dual-balloon selective arterial perfusion cannula  200  until it reaches the aortic arch, at which point, it branches off selectively or subselectively into the left or right carotid artery. The stent placement catheter  240  is advanced through the guiding catheter  250  to place the stent  230  in the carotid artery. If it is deemed necessary to make a transition to a stopped heart procedure, either electively or in the event of an emergency, the first  204  and second  205  aortic occlusion balloons are inflated to occlude the aortic lumen. The guiding catheter  250  is sealed between the second balloon  205  and the aortic wall. This configuration is particularly useful for selectively delivering prioritized perfusion and/or neuroprotective agents (e.g. neuroplegic agents) to the cerebral circulation to prevent neuroral damage from hypoperfusion or embolization that may result from carotid catheter procedures, including angioplasty, atherectorny or stent placement. 
     In an alternative embodiment to FIG. 1A or FIG. 2, the dual-balloon selective arterial perfusion cannula may be constructed with the arch perfusion lumen being of sufficient internal diameter to accommodate the guiding catheter of a carotid angioplasty or stent placement subsystem and having a catheter exit port located in the aortic arch between the first and second occlusion balloons. 
     FIG. 3A shows a third exemplary embodiment of the system for performing catheter based medical procedures with protective circulatory support in high risk patients. The system of FIG. 3A uses a selective arterial perfusion cannula  300  having first  304  and second  305  external flow control members in the form of selectively deployable external catheter flow control valves. External catheter valves suitable for use as external flow control members are described in U.S. Pat Nos. 5,833,671 and 5,827,237 as well as commonly owned, copending U.S. patent application Ser. No. 08/665,635 which are hereby incorporated by reference in their entirety. 
     The dual-valve, selective arterial perfusion cannula  300  is configured for retrograde introduction into the patient&#39;s aorta via a peripheral arterial access point, such as the femoral artery. Referring to FIG. 3B, the dual-valve, selective arterial perfusion cannula  300  has a tubular shaft  102  that includes an arch perfusion lumen  126 , a cardioplegia or distal perfusion lumen  153 , one or two valve actuation members and/or lumens  158  and  159  and, optionally, a corporeal perfusion lumen  151  and a root pressure lumen  179 . A first, upstream external catheter flow control valve  304  is mounted on the tubular shaft  102  so that it is positioned in the ascending aorta between the coronary arteries and the right brachiocephalic artery. A second, downstream external catheter flow control valve  305  is mounted on the tubular shaft so that it is positioned in the descending aorta downstream of the left subclavian artery. In one particularly preferred embodiment, the first, upstream external catheter flow control valve  304  is an antegrade valve that allows greater fluid flow in the antegrade direction than in the retrograde direction, and the second, downstream external catheter flow control valve  305  is a retrograde valve that allows greater fluid flow in the retrograde direction than in the antegrade direction. The optional corporeal perfusion lumnen  151  extends through the tubular shaft  102  from a corporeal perfusion fitting  121  on the proximal end of the catheter  300  to one or more corporeal perfusion ports  130  on the tubular shaft  102  proximal to the downstream occlusion valve  305 . 
     If the cannula  300  is constructed without the optional corporeal perfusion lumen  151 , corporeal perfusion can be provided through a coaxial or collateral perfusion carnula. The arch perfusion lumen  126  extends through the tubular shaft  102  from an arch perfusion fitting  122  on the proximal end of the catheter  300  to one or more arch perfusion ports  103  on the tubular shaft  102  between the upstream occlusion valve  304  and the downstream occlusion valve  305 . The cardioplegia or distal perfusion lumen  153  extends through the tubular shaft  102  from a cardioplegia fitting  132  on the proximal end of the catheter to one or more cardioplegia ports  116  on the tubular shaft  102  distal to the upstream occlusion valve  304 . The distal perfusion lumen  153  is made with an internal diameter sufficient to accommodate the catheters of the therapeutic catheter subsystem as well as the ability to deliver fluid therethrough. Optionally, the arterial cannula may also include a root pressure lumen  179  that extends through the tubular shaft from a pressure fitting  169  on the proximal end of the catheter to a pressure port  189  on the tubular shaft distal to the upstream occlusion valve  304 . 
     The therapeutic catheter subsystem may take one of many possible forms. By way of example, the system of FIG. 3A is shown with a coronary atherectomy subsystem, including an atherectomy catheter  390 , a guiding catheter  105  and a guidewire  190 . The distal perfusion lumen  153  of the dual-valve, selective arterial perfusion cannula  300  should be made with an internal diameter sufficient to accommodate the chosen guiding catheter  105  with additional clearance for easy insertion and manipulation of the guiding catheter  105  as well as delivery of fluid. In addition, the distal perfusion lumen  153  may be lined with a lubricious material, such as a fluoropolymer like PTFE, to facilitate insertion and manipulation of the guiding catheter  105 . Alt&amp;rnatively, the guiding catheter  105  of the angioplasty subsystem may be integrated into the dual-valve, selective arterial perfusion cannula  300  to create a combined dual-purpose device. A Y-fitting with a hemostasis valve  1132  or compression fitting is provided at the proximal end of the distal perfusion lumen  153  of the dual-valve, selective arterial perfusion cannula  300  to allow insertion and withdrawal of the therapeutic catheter subsystem without excessive bleeding or leaking of perfusate. 
     Alternatively, dual-valve, selective arterial perfusion cannula  300  can be constructed without the Y-fitting and hemostasis valve and with a smaller diameter distal perfusion lumen for operating the system by the method described above in connection with FIG.  2 . 
     FIG. 4 shows a fourth embodiment of the system for performing catheter procedures in high risk patients using a perfusion shunt device  450 , mounted on a selective arterial perfusion cannula  400 , for selective perfusion of a patient&#39;s cerebral circulation and upper extremities, while the beating heart supplies the viscera and lower extremities with blood. Suitable perfusion shunt devices  450  for this application are described in detail in commonly owned, copending patent application 60/069,470, filed Dec. 15, 1997 and corresponding utility application 09/212,580 filed Dec. 14, 1998 by Macoviak et al., which are hereby incorporated by reference in their entirety. The system of FIG. 4, includes a venous cannula  106  that is inserted into a large vein of the patient&#39;s circulatory system and connected by way of connector tubing to a cardiopulmonary support system  114 . Oxygenated blood from the output of the cardiopulmonary support system  114  is directed to an arch perfusion lumen of the perfusion shunt device  450  and out the arch perfusion ports  103 . 
     In a simplified version of this embodiment, the venous cannula  106  can be replaced by an arterial drainage cannula for draining oxygenated blood from the patient. A perfusion pump redirects the oxygenated blood through an optional heat exchanger to cool or warm the blood, then to an arch perfusion lumen of the perfusion shunt device. This embodiment of the system avoids the complexity of a blood oxygenator by using the patient&#39;s own lungs to supply oxygenated blood to the arch perfusion lumen. This simplified version of the system cannot be used for complete cardiopulmonary bypass. 
     The arch perfusion shunt device  450  has an expandable shunt conduit  411  mounted on an elongated catheter shaft  102 . The expandable shunt conduit  411  has an upstream sealing member  404  at the upstream end of the conduit  411  and a downstream sealing member  405  at the downstream end of the conduit  411 . The upstream and downstream sealing members  404  and  405  may be inflatable, toroidal balloons, as illustrated, or external flow control valves may be used. A common inflation lumen or separate inflation lumens  158  and  159  extend through the catheter shaft  102  from one or more inflation; fittings  128  and  129  on the proximal end of the catheter  400  to inflation ports  491 ,  492  within the upstream sealing member  404  and the downstream sealing member  405 . The expandable shunt conduit  411  is inserted into the patient&#39;s aorta in a collapsed state and is expanded within the aortic arch with the inflated upstream sealing member  404  positioned between the aortic valve and the brachiocephalic artery and the inflated downstream sealing member  405  positioned downstream of the left subclavian artery. An arch perfusion lumen within the catheter shaft extends from a perfusion fitting  122  at the proximal end of the catheter shaft to one or more arch perfusion ports  103  within the annular chamber  489  surrounding the shunt conduit  411 . Optionally, the arch perfusion shunt device  450  may also include a shunt conduit lumen occlusion balloon for converting the patient to full cardiopulmonary bypass with cardioplegic arrest. 
     The system includes a therapeutic catheter subsystem, for example a coronary stent placement subsystem is illustrated, including a stent placement catheter  490 , which may be an angioplasty balloon catheter, a guiding catheter  105  and a guidewire  442 . The therapeutic catheter subsystem may also take the form of a coronary or carotid angioplasty, stent placement or atherectomy subsystem, an aortic or mitral valvuloplasty subsystem or other known therapeutic catheter system. The catheters of the therapeutic catheter subsystem may be placed through the lumen of the shunt conduit  474 , as illustrated, particularly for catheter procedures in the heart or the coronary arteries. 
     Alternatively, the catheters of the therapeutic catheter subsystem may be placed exterior to the shunt conduit  411 . This configuration is particularly useful when the perfusion shunt device  450  is being used as a safety backup in beating heart catheter procedures or when performing carotid procedures. 
     In another alternative construction, the perfusion shunt device  450  may be constructed with the arch perfusion lumen being of sufficient internal diameter to accommodate the guiding catheter  472  of a carotid angioplasty or stent placement subsystem and having a catheter exit port  475  located in the aortic arch between the upstream  404  and downstream sealing members  405 . 
     Furthermore, a corporeal perfusion lumen connected to corporeal perfusion ports  130  may be provided either through the therapeutic catheter subsystem as depicted or through the selective arterial perfusion cannula  400  by adding an additional corporeal lumen to either to make the system completely compatible for emergency bypass. Alternatively, a separate contralateral or collateral cannula may be used independently. 
     FIG. 5A shows an alternative embodiment of the system of the present invention. In this embodiment, the therapeutic catheter subsystem includes a guiding catheter  105  having a first  104  and a second  101  external flow control member in the form of inflatable occlusion balloons, as illustrated, or of selectively deployable external catheter flow control valves. Referring to FIG. 5B the guiding catheter  105  has an elongated tubular shaft  102  with a central instrument lumen  153  and one or two balloon inflation lumens  158  and  159  or valve actuation lumens. The main aortic catheter of the selective aortic perfusion and cardiopulmonary bypass subsystem is eliminated. 
     The aortic segmentation function of the aortic catheter is fulfilled by the first  104  and second  101  external flow control members on the guiding catheter  105 . The perfusion functions are fulfilled by a first peripheral arterial cannula  570  placed in a lower extremity, for example in the femoral artery and a second peripheral arterial cannula  580  that is placed in an upper extremity, for example in the left or right subelavian or axillary artery and by the central instrument lumen  153  of the guiding catheter. The first peripheral arterial cannula  570  supplies oxygenated blood to the corporeal circulation, the second peripheral arterial cannula  580  supplies oxygenated blood and/or neuroprotective agents to the cerebral circulation. The central instrument lumen  153  of the guiding catheter  105  can be used to deliver oxygenated blood and/or cardioplegic and/or protective agents to the coronary circulation. 
     FIG. 6 shows, another alternative embodiment of the system of the present invention. In this embodiment, the main aortic catheter of the selective aortic perfusion and cardiopulmonary bypass subsystem has been replaced with a low profile dual-balloon occlusion catheter  601  having a first  604  and a second external flow control members  605  in the form of inflatable occlusion balloons, as illustrated, or of selectively deployable external catheter flow control valves. 
     The low profile dual-balloon occlusion catheter  601  is placed in parallel with the guiding catheter  105  of the therapeutic, catheter subsystem. The low profile dual-balloon occlusion catheter  601  has an elongated catheter shaft  602  having one or two balloon inflation or valve actuation lumens and, optionally, a guidewire lumen. Alternatively, the elongated catheter shaft  602  may be constructed similar to a guidewire body with no additional lumens for easy insertion and extremely low profile. 
     The aortic segmentation function of the system is fulfilled by the first  604  and second  605  external flow control members on the low profile dual-balloon occlusion catheter  601 , and the perfusion functions are fulfilled by a first peripheral arterial cannula  570  placed in a lower extremity, for example in the femoral artery, and the second peripheral arterial cannula  580  that is placed in an upper extremity, for example in the left or right subclavian or axillary artery and or by the instrument lumen of the guiding catheter. 
     The first peripheral arterial cannula  570  supplies oxygenated blood to the corporeal circulation, the second peripheral arterial cannula  580  supplies oxygenated blood and/or neuroprotective agents to the cerebral circulation, and the instrument lumen of the guiding catheter  105  can be used to deliver cardioplegic and/or protective agents to the coronary circulation. The extreme low profile of the low profile dual-balloon occlusion catheter  601  makes it especially useful as an emergency bail out catheter because it can be placed through an existing arterial access site or introducer sheath, and the peripheral arterial cannulas and the venous cannula can be placed percutaneously to quickly initiate cardioplegic arrest and/or selective cerebral perfusion in the event of an unforeseen complication during a catheter based procedure. 
     Although the examples given include many specific uses, they are intended as illustrative of only some of the possible embodiments of the invention. Other embodiments and modifications will, no doubt, occur to those skilled in the art. For example, each of the aortic catheters or cannulas of the system can be configured for peripheral placement via the subclavian or axillary artery or for central placement via an aortotomy incision, as described in conmmonly owned, copending patent application 60/067,945 and the corresponding utility application 09/205,753 filed Dec. 4, 1998 which are hereby incorporated by reference in their entirety. In addition, the functions of the aortic catheters or cannulas of the system can be replaced by two or more separate catheters with the first and second flow control members mounted thereon, as described in commonly owned, copending patent application 60/084,835 and the corresponding utility application 09/306,555 filed May 6, 1999 which are hereby incorporated by reference in their entirety. 
     By way of example, FIG. 7 illustrates an embodiment of a system where aortic segmentation and/or perfusion is fulfilled by a first catheter having an upstream occlusion member adapted for occluding the patient&#39;s ascending aorta which is expandable from a first elongated catheter shaft. A second catheter having a second elongated catheter shaft has a downstream occlusion member mounted thereon which is sized and configured for occluding the patient&#39;s descending aorta. The catheter device for performing a diagnostic or therapeutic catheter procedure within a patient&#39;s aorta maybe provided through another peripheral access site, in parallel with the access site of one of the aforementioned catheters or coaxially through either one of the previously mentioned catheters. 
     One method of using the previously described catheters is to insert a first peripheral arterial cannula  300  in an upper extremity, for example the left or right subclavian artery or axillary artery and place a second peripheral arterial cannula  400  in a lower extremity, for example in the femoral artery. A first upstream occlusion member  104 , in this illustrative embodiment in the form of an external flow control valve; is mounted on the first catheter shaft  302 . A second flow control member  404 , in this illustrative embodiment in the form of an occlusion balloon, is mounted on the second catheter shaft  402 . The perfusion functions are fulfilled by the first peripheral arterial cannula  300  which supplies oxygenated blood and/or neuroprotective agents to the arch circulation through arch ports  103 , and the second peripheral arterial cannula  400  which supplies oxygenated blood to the corporeal circulation through corporeal ports  130 . In addition, the second perfusion cannula  400  can provide for the perfusion functions of both the arch and corporeal circulations which would allow for a low profile cannula design for the first perfusion cannula  300  which would serve as a flow control regulator catheter and or therapeutic catheter delivery catheter with optional cardioplegia delivery and aspiration of the aortic root. A central instrument lumen can be located in either one or both of the peripheral arterial cannulas depending upon the procedure to be performed. In this illustrative embodiment both perfusion cannulas have an instrument lumen. A carotid stent assembly is being placed through the instrument lumenr of the second perfusion catheter  400  and a coronary stent is being placed through the instrument lumen of the first perfusion catheter  300 . In addition, either one or both of the occlusion members may be incorporated into the therapeutic/diagnostic catheters as illustrated in connection with FIG.  5 A. 
     Thus, the examples given should only be interpreted as illustrations of some of the preferred embodiments of the invention. It is understood that the figures are examples of illustrative embodiments and any of the catheter systems may be compatible with other catheter systems described in different figures, therefore the full scope of the invention should be determined by the appended claims and their legal equivalents.