looking first at fig1 - 3 , there is shown an access system 5 formed in accordance with the present invention . access system 5 generally comprises an erectable proximal isolation barrier 10 and an erectable distal isolation barrier 15 for disposition within the lumen of a vascular structure or other body lumen . erectable proximal isolation barrier 10 and erectable distal isolation barrier 15 are formed so that they can ( i ) initially assume a diametrically - reduced configuration so as to facilitate insertion of access system 5 to a site where a procedure ( e . g ., therapy , diagnosis , exploration , etc .) is to be conducted , and ( ii ) thereafter assume a diametrically - expanded configuration once at the procedure site so as to form a fluid - tight ( occlusive ) seal against the wall of the vascular structure , whereby to isolate a segment of the vascular structure from the remainder of the vascular structure , e . g ., while a procedure is performed . in one preferred form of the invention , proximal isolation barrier 10 and distal isolation barrier 15 have a peripheral surface texture to help ensure that the barriers will maintain their position in the vascular structure once deployed . by way of example but not limitation , such peripheral surface texturing may comprise dimpling , circumferential ribbing , etc . in this respect it will be appreciated that the proximal and distal isolation barriers should remain in place when systolic pressure is present on the outer surfaces of each of the isolation barriers and atmospheric pressure is present within the isolated segment of the vascular structure . furthermore , erectable proximal isolation barrier 10 and erectable distal isolation barrier 15 are formed so that they may be collapsed when desired so as to facilitate removal of access system 5 from the vascular structure , e . g ., at the conclusion of the procedure . by way of example but not limitation , erectable proximal isolation barrier 10 and erectable distal isolation barrier 15 may be formed by inflatable / deflatable balloons , compressible / expandable superelastic shape memory alloy ( e . g ., nitinol ) rings , etc . as a result of this construction , when access system 5 has been deployed at a desired point in a vascular structure or other body lumen , and erectable proximal isolation barrier 10 and erectable distal isolation barrier 15 have been expanded to their sealing condition , access system 5 can isolate a segment of the vascular structure ( i . e ., the portion located between erected proximal isolation barrier 10 and erected distal isolation barrier 15 ) from the remainder of the vascular structure , e . g ., while a procedure is performed . this can be important in a variety of situations , e . g ., where the procedure may dislodge debris which could harm downstream tissue . access system 5 is preferably constructed so that erectable proximal isolation barrier 10 and erectable distal isolation barrier 15 may be diametrically - expanded and diametrically - reduced independently of one another . in other words , access system 5 is preferably constructed so that proximal isolation barrier 10 may be diametrically - expanded or diametrically - reduced regardless of the condition of distal isolation barrier 15 , and vice - versa . where erectable proximal isolation barrier 10 and erectable distal isolation barrier 15 are formed out of an inflatable / deflatable balloon , access system 5 also comprises channels for delivering fluid ( a liquid or a gas ) for inflating / deflating the balloons . by way of example but not limitation , a channel 16 may be provided for inflating the balloon of erectable proximal isolation barrier 10 and a channel 17 may be provided for inflating the balloon of erectable distal isolation barrier 15 . access system 5 further comprises a bypass channel 20 secured to , and extending between and through , proximal isolation barrier 10 and distal isolation barrier 15 . bypass channel 20 comprises a central lumen 25 ( fig3 ) which opens proximal to proximal isolation barrier 10 and distal to distal isolation barrier 15 , whereby to permit flow from one side of access system 5 to the other side of access system 5 . as a result of this construction , when access system 5 is deployed in a vascular structure so as to isolate a segment of the vascular structure from the remainder of the vascular structure , access system 5 can still permit blood to flow uninterrupted through the bypass channel 20 which traverses the isolated segment of the vascular structure . this can be important in a variety of physiologic situations , e . g ., such as where continued blood flow is important for the oxygenation of downstream tissues . in one embodiment , the upstream isolation barrier may be configured so as to channel blood flow into bypass channel 20 . thus , for example , in fig1 , proximal isolation barrier 10 may be configured so as to channel blood flow into bypass channel 20 . by way of example but not limitation , the upstream side of proximal isolation barrier 10 may be formed with a concave ( e . g ., funnel - shaped ) surface surrounding the entrance to bypass channel 20 . thus it will be seen that access system 5 provides both zone isolation ( via proximal isolation barrier 10 and distal isolation barrier 15 ) and distal perfusion ( via bypass channel 20 ). these features can be important in a variety of situations where zone isolation and distal perfusion are both desirable and / or necessary , e . g ., where vascular trauma needs to be temporarily stabilized while the patient is transported to another site for further treatment , where an aneurysm ( e . g ., abdominal or thoracic , iliac or femoral , etc .) is bleeding and / or threatening to rupture , or actually has ruptured , etc . furthermore , it should be appreciated that access system 5 may be used on both the arterial and venous sides of the circulation system . access system 5 further comprises a working catheter 30 which passes through proximal isolation barrier 10 and provides access ( e . g ., for medical instruments including but not limited to cutting instruments , biopsy instruments , closure instruments , material delivery systems , endoscopes , etc ., including for the delivery of adhesives and / or agents for promoting thrombus , gene therapeutic agents , etc .) to the wall of the isolated length of the vascular structure . preferably , working catheter 30 can slide forward and backward through proximal isolation barrier 10 such that working catheter 30 can be positioned anywhere between proximal isolation barrier 10 and distal isolation barrier 15 . additionally , access system 5 is preferably configured so that working catheter 30 can be rotated in order that the distal tip 33 of working catheter 30 can access substantially the entire circumference of the isolated vessel . access system 5 is preferably configured so as to be mountable on a guidewire 35 , so that access system 5 may be delivered to a desired position within the vascular structure . by way of example but not limitation , access system 5 may comprise a guidewire channel 40 mounted to proximal isolation barrier 10 and / or working catheter 30 ( e . g ., proximal to proximal isolation barrier 10 , as shown in fig1 ), such that guidewire 35 may be received within bypass channel 20 and guidewire channel 40 , whereby to permit controlled delivery of access system 5 to a desired location within a vascular structure . in one preferred form of use , and looking now at fig1 - 3 , access system 5 may be used to isolate , bypass and access the wall of a vascular structure . by way of example but not limitation , access system 5 may be used to isolate , bypass and access a lateral aneurysm 45 formed in the wall of a vascular structure 50 . in this case , guidewire 35 is first deployed down vascular structure 50 . then access system 5 , with proximal isolation barrier 10 and distal isolation barrier 15 set in their diametrically - reduced condition , is advanced over the guidewire to a point adjacent to lateral aneurysm 45 . next , proximal isolation barrier 10 and distal isolation barrier 15 are set in their diametrically - expanded condition , so as to conform to , and seal against , the wall of the vascular structure and thereby create an isolation zone 55 which encompasses lateral aneurysm 45 . however , it will be appreciated that blood is still able to flow past the isolation zone ( e . g ., from flow zone 60 to flow zone 65 ) via bypass channel 20 . to the extent that the proximal end of working catheter 30 is open to the atmosphere , blood in the isolation zone may flow out of the isolation zone via the working catheter and be replaced with air . alternatively , the working catheter may be used to introduce another fluid ( e . g ., saline ) into the isolation zone . at this point , instruments may be advanced through working catheter 30 so as to access , and provide therapy to , lateral aneurysm 45 . such instruments may include , but are not limited to , cutting instruments , biopsy instruments , closure instruments , material delivery systems , endoscopes , etc . at the conclusion of the procedure , proximal isolation barrier 10 and distal isolation barrier 15 are set in their diametrically - reduced condition , and then access system 5 is withdrawn along guidewire 35 . finally , guidewire 35 is removed from vascular structure 50 . any debris created in isolation zone 55 during the procedure may be removed by withdrawing blood / debris from isolation zone 55 . in one form of the invention , blood / debris evacuation may be effected by applying suction via working catheter 30 while both proximal isolation barrier 10 and distal isolation barrier 15 remain erected . in another form of the invention , blood / debris evacuation may be effected by first returning proximal isolation barrier 10 to its diametrically - reduced configuration while retaining distal isolation barrier 15 in its diametrically - expanded configuration , then removing blood / debris via suction , and then returning distal isolation barrier 15 to its diametrically - reduced configuration so that access system 5 may be removed from the vascular structure . this latter approach may be particularly applicable to angioplasty in the coronary and / or carotid arteries . fig4 and 5 show an alternative form of access system 5 . the access system shown in fig4 and 5 is substantially the same as the access system shown in fig1 - 3 , except that guidewire channel 40 extends parallel to , but spaced from , bypass channel 20 and bypass channel 20 is positioned diametrically outboard so as to sit proximate to the wall of the vascular structure . if desired , working catheter 30 may be made detachable from the remainder of access system 5 . this feature can be advantageous where longer term isolation of a vascular region is desired , e . g ., for aneurysm embolization , since it allows the relatively large - bore working catheter to be removed , leaving only the zone isolation apparatus and fluid bypass apparatus present in the body lumen . as noted above , proximal isolation barrier 10 and distal isolation barrier 15 are designed so as to be able to assume a diametrically - expanded configuration or a diametrically - reduced configuration . as also noted above , proximal isolation barrier 10 and distal isolation barrier 15 may comprise an inflatable / deflatable balloon or a compressible / expandable ring , etc . in this respect it should be appreciated that where proximal isolation barrier 10 and distal isolation barrier 15 comprise an inflatable / deflatable balloon , the balloon may extend across substantially the entire diameter of the vascular structure . alternatively , the balloon may extend only about the periphery of the diameter of the vascular structure , and a membrane 67 may extend across the interior of the balloon , such as is shown in fig3 . a similar construction may be used where proximal isolation barrier 10 and distal isolation barrier 15 comprise a compressible / expandable ring , e . g ., such as one formed from a superelastic shape memory alloy . again , a membrane may extend across the interior of the ring . fig6 - 9 show an alternative form of access system 5 . the access system shown in fig6 - 9 is substantially the same as the access system shown in fig1 - 3 except that proximal isolation barrier 10 and distal isolation barrier 15 comprise multi - segmented balloons 70 , and working catheter 30 includes an opening 75 connected to the lumen of working catheter 30 . the use of these multi - segmented balloons 70 to form proximal isolation barrier 10 and distal isolation barrier 15 provide a wider , more stable barrier without restricting blood flow through bypass channel 20 . as seen in fig9 , channels 80 may be provided between adjacent balloons so that the interior of the balloons are in communication with one another . fig1 - 12 show an alternative form of access system 5 . the access system shown in fig1 - 12 is substantially the same as the access system shown in fig6 - 9 except that channels 80 may be replaced with holes 85 so that the interior of the balloons are in communication with one another . access system 5 may be deployed in a vascular structure or other body lumen using a delivery catheter . more particularly , and looking next at fig1 , 14 , 14 a and 15 - 20 , a delivery catheter 100 comprising a delivery sheath 103 may be provided for advancing access system 5 to a procedure site within a vascular structure ( or other body lumen ), and for erecting access system 5 in the manner previously discussed . furthermore , delivery catheter 100 may be used for advancing instruments down to the procedure site and / or removing debris from the procedure site ( e . g ., a fusiform aortic aneurysm 104 of the type shown in fig1 a ), again in the manner previously discussed . finally , delivery catheter 100 may be used to collapse access system 5 and remove it from the vascular structure ( or other body lumen ). in the case where access system 5 comprises inflatable / deflatable balloons in its proximal isolation barrier and / or distal isolation barrier 15 , delivery catheter 100 may contain one or more fluid supply tubes 105 for inflating / deflating the balloons . it should be appreciated that delivery sheath 103 of delivery catheter 100 may also perform the function of an introducer sheath , in the sense that it can be secured to the exterior tissue of the patient once the delivery catheter is properly positioned . a hemostatic valve 110 , with a side port 115 , is preferably located on the proximal end of the delivery catheter to prevent the loss of blood through the catheter while still allowing the insertion of access system 5 . it should be appreciated that access system 5 can be used to provide a wide range of therapies to vascular structures , e . g ., aneurysm therapy , lesion therapy , infusion therapy , gene therapy , photodynamic therapy , etc . access system 5 may also be used to repair tears , flaps and leaks in a vascular structure . furthermore , it should be also be appreciated that the present invention can be used to access structures other than vascular structures , e . g ., the esophagus , stomach , small or large bowel , ureter , bladder , urethra , bronchus , bile duct , ear , nose , fallopian tube , other tubular or hollow structures within the human body , etc . in essence , the present invention can be advantageously used in substantially any body lumen where isolation , access and / or fluid bypass are desired . additionally , it should be appreciated that the zone which is isolated between the proximal and distal isolation barriers could be of varying lengths , and of various diameters as well . furthermore , many different catheter shapes and sizes may be utilized . without limiting the breadth and scope of the present invention , it is anticipated that the present invention is particularly well suited for treating fusiform aneurysms in the aorta and the larger peripheral blood vessels . furthermore , without limiting the breadth and scope of the present invention , it is anticipated that the present invention is particularly well suited for treating vascular trauma in a variety of situations where zone isolation and distal perfusion are both desirable and / or necessary , e . g ., where vascular trauma needs to be temporarily stabilized while the patient is transported to another site for further treatment . while the present invention has been described in terms of certain exemplary preferred embodiments , it will be readily understood and appreciated by one of ordinary skill in the art that it is not so limited , and that many additions , deletions and modifications may be made to the preferred embodiments discussed above while remaining within the scope of the present invention .
apparatus and method for accessing the wall of a body lumen while simultaneously providing zone isolation and fluid bypass capability , the apparatus comprising : an erectable proximal isolation barrier capable of making a sealing engagement with the wall of the body lumen ; an erectable distal isolation barrier capable of making a sealing engagement with the wall of the body lumen ; a bypass channel secured to , and extending between , the proximal isolation barrier and the distal isolation barrier , the bypass channel comprising a lumen communicating with the region proximal to the proximal isolation barrier and with the region distal to the distal isolation barrier ; and a working catheter passing through the proximal isolation barrier and terminating short of the distal isolation barrier , the working catheter providing a central lumen for providing access to the wall of the body lumen between the proximal isolation barrier and the distal isolation barrier .