Methods and devices for occluding the ascending aorta and maintaining circulation of oxygenated blood in the patient when the patient's heart is arrested

Abstract

A method and device for occluding a patient's ascending aorta, maintaining circulation of oxygenated blood in the patient and delivering cardioplegic fluid to arrest the patient's heart. An aortic occlusion catheter has an occluding member for occluding the ascending aorta. The aortic occlusion catheter passes through a cannula. Delivery of oxygenated blood is accomplished through either the cannula or the aortic occlusion catheter.

Description

BACKGROUND OF THE INVENTION

The present invention is directed to methods and devices for occluding a patient's ascending aorta and maintaining circulation of oxygenated blood in the patient when the patient's heart is arrested. Such devices and methods are useful for performing various procedures on a patient's vascular system and heart such as the procedures described in U.S. Pat. Nos. 5,584,803 and 5,682,906 which describe coronary artery bypass grafting (CABG) and valve procedures, respectively. Another device and method for occluding a patient's ascending aorta is described in Re. 35,352.

The methods and devices described in the above-mentioned patents use an internal occlusion device to occlude the ascending aorta rather than a conventional external cross-clamp. Use of an internal occlusion device may reduce strokes as compared to conventional external cross-clamps since external cross-clamps distort and compress the aorta which may release emboli leading to strokes.

It is an object of the invention to provide alternative methods and devices for occluding a patient's ascending aorta and maintaining circulation of oxygenated blood when the patient's heart is arrested.

SUMMARY OF THE INVENTION

In accordance with the object of the invention, the present invention provides alternative methods and devices for occluding a patient's ascending aorta and maintaining circulation of oxygenated blood in a patient when the patient's heart is arrested.

In a first preferred method and device of the present invention, an aortic occlusion device having a blood delivery lumen and an occluding member is introduced into the patient's aortic arch. The occluding member has an interior in fluid communication with the blood delivery lumen so that delivery of oxygenated blood inflates the occluding member. An advantage of this method is that a separate inflation lumen is not necessary. The aortic occlusion device preferably passes through a cannula having a y-arm with the aortic occlusion catheter passing through an arm of the y-arm. The other arm of the y-arm connector is coupled to the source of oxygenated blood so that bypass support can be maintained even when the aortic occlusion device has been removed.

In another preferred method and device, oxygenated blood is delivered to the patient through the aortic occlusion catheter. The aortic occlusion catheter also passes through a cannula with a y-arm connector so that bypass support can be maintained when the aortic occlusion device is removed. The aortic occlusion device also preferably includes a lumen for delivering cardioplegic fluid and venting the ascending aorta and a pressure lumen for measuring pressure in the ascending aorta. If the lumens are not provided in the aortic occlusion device, delivery of cardioplegic fluid, venting of the ascending aorta and pressure monitoring may be accomplished with the cannula.

In another preferred device, the aortic occlusion device has an occluding member mounted to a side of the catheter. The occluding member has a pathway therethrough which is in communication with a lumen in the aortic occlusion catheter. The pathway directs cardioplegic fluid toward the coronary ostia while the aortic occlusion device directs the oxygenated blood in the direction of normal blood flow in the aorta.

These and other aspects and advantages of the present invention will become apparent from the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an aortic occlusion device;

FIG. 2 is a cross-sectional view of a first step in forming the aortic occlusion catheter of FIG. 1 ;

FIG. 3 is a cross-sectional view of the structure of FIG. 2 after heating;

FIG. 4 is a cross-sectional view of a further step in forming the aortic occlusion catheter of FIG. 1 ;

FIG. 5 is a cross-sectional view of FIG. 1 along line I—I;

FIG. 6 shows a cannula;

FIG. 7 shows an enlarged view of the distal end of the cannula of FIG. 6 ;

FIG. 8 is a plan view of a ring;

FIG. 9 is a side view of the ring;

FIG. 10 shows a n introducer with an incising element in a retracted position;

FIG. 11 shows the introducer with the incising element in an exposed position;

FIG. 12 shows the aortic occlusion device and cannula passing through a penetration in the ascending aorta;

FIG. 13 shows another aortic occlusion device passing through the cannula and into the patient's ascending aorta;

FIG. 14 shows yet another aortic occlusion device;

FIG. 15 shows still another aortic occlusion device;

FIG. 16 shows a final aortic occlusion device;

FIG. 17 illustrates a preferred method of introducing the aortic occlusion device;

FIG. 18 shows another preferred aortic occlusion device with the balloon occluding the ascending aorta; and

FIG. 19 shows the aortic occlusion device of FIG. 18 with the balloon deflated.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1 and 5 , an aortic occlusion device 2 is shown. The aortic occlusion device 2 has an occluding member 4 configured to occlude a patient's ascending aorta. The occluding member 4 is preferably a balloon but may also be a mechanically actuated member. The aortic occlusion device 2 has an inflation lumen 6 for inflating the occluding member 4 , a pressure lumen 8 for measuring pressure in the ascending aorta, and a lumen 10 for delivering cardioplegic fluid and/or venting the ascending aorta. The aortic occlusion device 2 is preferably manufactured and used in the manner described in U.S. patent application Ser. No. 08/782,113 but may also be manufactured in any other manner such as an extrusion.

The aortic occlusion device 2 is preferably substantially straight in an unbiased position, however, the aortic occlusion device 2 may also have a shaped end. For example, the aortic occlusion catheter 2 can have an L-shaped end which facilitates positioning the occluding member 4 in the ascending aorta depending upon the surgical approach. The aortic occlusion device 2 is preferably flexible so that it can be bent as necessary without kinking.

Referring to FIGS. 2-5 , a preferred method of forming the aortic occlusion device 2 is shown. FIG. 2 shows a longitudinal cross-section of a tube 12 , preferably a urethane tube, mounted on a teflon-coated mandrel 14 with the elongate element 16 wound helically around the tube 12 . The elongate element 16 is preferably a wire ribbon having a thickness of 0.003 inch and a width of 0.012 inch. The elongate element 16 is preferably wrapped around the tube 12 with a spacing of 0.010 inch. Another tube 20 is positioned over the elongate member 16 and a shrink tube (not shown) is positioned over the tube 20 . The entire structure is then heated to fuse the tubes together to form a reinforced tube 22 which is shown in longitudinal cross-section in FIG. 3 . The resulting reinforced tube 22 preferably has an inner diameter of about 0.100 inch and a wall thickness of about 0.010 inch.

Referring to FIG. 4 , a two-lumen member 24 is positioned against the reinforced tube 22 and a shrink tube 26 is positioned around the member 24 and reinforced tube 22 . The two-lumen member 24 has the inflation lumen 6 , which is used for inflating the occluding member 4 , and the pressure lumen 8 , which is used for pressure monitoring in the ascending aorta. The two-lumen member 24 is preferably an extrusion having a D-shaped outer surface in cross-section. The member 24 and tube 22 are then heated and the shrink tube 26 is removed to obtain the egg-shaped cross-sectional shape shown in FIG. 5 . The cross-sectional shape is preferably about 0.145 inch tall and 0.125 inch wide. The inflation lumen 6 is then pierced to provide an inflation path to the occluding member 4 and the occluding member 4 is then mounted to the shaft.

Referring to FIGS. 6 and 7 , a cannula 28 is shown which is used to return oxygenated blood to the patient when the patient's heart is arrested. The aortic occlusion device 2 is introduced into the patient through the cannula 28 as will be described below. The cannula 28 has a y-arm connector 30 with first and second arms 32 , 34 with each coupled to a lumen 35 . The second arm 34 has a hemostasis valve 36 which may be any hemostasis valve and is preferably a Thouy-Borst valve. The cannula 28 has a reinforced body 38 which is preferably formed in the manner described in U.S. patent application Ser. No. 08/749,683, which is hereby incorporated by reference, however, any other method may be used including extrusion. The distal end 40 of the cannula 28 is beveled and has an open end 42 and two side ports 44 for infusing oxygenated blood into the patient. A radiopaque markers 45 are provided at the distal end for visualization as discussed below.

Referring to FIGS. 6-9 , a ring 46 is attached to the distal end 40 of the cannula 28 . The ring 46 limits insertion of the cannula 28 into the vessel, stabilizes the cannula 28 , and receives purse-string sutures which provide hemostasis around the cannula 28 when the cannula 28 is positioned in a vessel. Referring to FIGS. 8 and 9 , the ring 46 has slots 48 which may receive purse-string sutures as will be described below.

Referring to FIGS. 10 and 11 , an introducer 50 is positioned in the cannula 28 to introduce the cannula 28 into a vessel. The introducer 50 has a connector hub 51 which is received by the hemostasis valve 36 on the second arm 32 of the cannula 28 to seal the space between the introducer 50 and cannula 28 . The introducer 50 has an incising element 52 for incising the vessel into which the cannula 28 is introduced. The incising element 52 is attached to a shaft 54 which is coupled to a trigger 56 for moving the incising element 52 from the retracted position of FIG. 10 to the exposed position of FIG. 11 . An o-ring seals 58 the space between an outer housing 60 and the shaft 54 . The incising element 52 is biased toward the retracted position by a spring 62 so that the incising element 52 is only exposed when the trigger 56 is actuated. When introducing the cannula 28 into the vessel, the trigger 56 is actuated to move the incising element 52 to the exposed position, the vessel is incised with the incising element 52 and the cannula 28 is inserted through the incision. As will be described below, one or more purse-string sutures are then used to form a hemostatic seal around the cannula 28 . The incising element 52 may be omitted if a separate incising device is used.

Referring to FIG. 12 , the cannula 28 is positioned in a patient's ascending aorta with the aortic occlusion device 2 passing through the hemostasis valve 36 . Placement of the cannula 28 and aortic occlusion device 2 into the position of FIG. 12 is described below. Referring to FIGS. 5 and 12 , the lumen 10 is coupled to a source of cardioplegic fluid 64 , the inflation lumen 6 is coupled to a source of inflation fluid 66 , and the pressure lumen 8 is coupled to the pressure monitor 68 for measuring pressure in the ascending aorta. The lumen 10 is also coupled to a vacuum source 70 for venting the ascending aorta.

The first arm 32 of the cannula 28 is coupled to a source of oxygenated blood 72 so that blood is delivered through the lumen 35 of the cannula 28 with the blood passing through the annular area between the cannula 28 and the aortic occlusion device 2 . The oxygenated blood passing through the open end 42 of the cannula 28 is directed at the occluding member 4 so that the oxygenated blood is not directed at the wall of the aorta. An advantage of directing the oxygenated blood at the occluding member 4 is that the fluid is dispersed radially outward by the occluding member 4 before coming into contact with the wall of the aorta. By directing the blood at the occluding member 4 , rather than at the wall of the aorta, the likelihood of releasing emboli from the wall of the aorta may be reduced. Oxygenated blood is also directed through the side ports 44 so that oxygenated blood is delivered to the patient even if the occluding member 4 blocks the open end 42 of the cannula 28 .

Referring to FIG. 13 , another aortic occlusion device 2 A is shown having a balloon 76 which is inflated with the oxygenated blood delivered to the patient. The aortic occlusion device 2 A has a blood flow lumen 78 which is fluidly coupled to the interior of the balloon 76 for inflating the balloon 76 . Oxygenated blood is then delivered to the patient through an opening 80 , preferably a number of openings, in the balloon 76 . An advantage of the aortic occlusion device 2 A is that a separate inflation lumen is not required since occlusion is accomplished by simply delivering oxygenated blood through the aortic occlusion device 2 A. The aortic occlusion device 2 A may also include a pressure lumen 82 for measuring pressure in the ascending aorta and a lumen 84 for delivering cardioplege and venting the ascending aorta. The aortic occlusion device 2 A is preferably formed in the manner described above except that the lumen 78 is sized large enough to provide sufficient flow of oxygenated blood at an acceptable pressure. Acceptable blood flow rates and pressures are disclosed in the above-mentioned patents and patent applications which have been incorporated by reference. Although it is preferred to manufacture the device in the manner described above, the aortic occlusion device 2 A may also simply be an extrusion or laminated structure. The balloon 76 is preferably made of silicone having a thickness of between 0.005 and 0.009 inch.

The aortic occlusion catheter 2 A passes through the cannula 28 so that oxygenated blood can be delivered to the patient when the aortic occlusion device 2 A is removed. The cannula 28 is preferably the cannula 28 described above with the first arm 32 coupled to the source of oxygenated blood 72 , pressure monitor 68 , and source of cardioplegic fluid via valve 86 . Thus, cardioplegic fluid and oxygenated blood can be directed through the lumen 35 in the cannula 28 if the lumen 84 is not provided in the aortic occlusion catheter 2 A. The cannula 28 has the hemostasis valve 36 to seal the space between the cannula 28 and aortic occlusion device 2 A.

Referring to FIG. 14 , yet another aortic occlusion device 2 B is shown. The aortic occlusion device 2 B has the occluding member 4 and the inflation lumen 6 coupled to the source of inflation fluid 66 for inflating the occluding member 4 . The aortic occlusion device 2 B also has a lumen 88 for delivering oxygenated blood to the patient from the source of oxygenated blood 64 . The shaft is preferably reinforced with a wire in the manner described above except that the lumen 88 is sized large enough to provide adequate blood flow to the patient at an acceptable pressure as discussed above. The cannula 28 is preferably the same as the cannula 28 described above and the aortic occlusion device 2 B is introduced through the cannula 28 in the manner described below. The first arm 34 of the cannula 28 has the hemostasis valve 36 for receiving the aortic occlusion device 2 B. The second arm 32 is coupled to a valve 90 which determines whether cardioplegic fluid or oxygenated blood is delivered through the lumen 35 in the cannula 28 . Valve 92 determines whether oxygenated blood is delivered through the lumen 35 in the cannula 28 or the lumen 88 in the aortic occlusion device 2 B. An advantage of the aortic occlusion device 2 B and cannula 28 is that bypass support can be provided before inflating the occluding member 4 and can also be maintained after the aortic occlusion device 2 B is removed from the cannula 28 .

Referring to FIGS. 15 , another aortic occlusion device 2 C is shown. The aortic occlusion device 2 C has a balloon 94 mounted to a side of a shaft 96 . The aortic occlusion device 2 C has an inflation lumen 98 for inflating the balloon 94 through inflation outlet 100 and a lumen 102 for delivering cardioplegic fluid from the source of cardioplegic fluid 64 and venting the ascending aorta using the vacuum source 70 . The aortic occlusion device 2 C also has a blood flow lumen 104 for delivering oxygenated blood to the patient from the source of oxygenated blood 72 . A fluid path 106 passes through the balloon 94 which is in fluid communication with the lumen 102 so that cardioplegic fluid is delivered through the fluid path 106 in the balloon 94 . An advantage of the aortic occlusion device 2 C is that the cardioplegic fluid can be delivered toward the aortic valve while oxygenated blood is directed in the direction of normal blood flow in the aortic arch. The distal end of the aortic occlusion device has an open end 108 and side ports 110 through which the oxygenated blood is delivered. The aortic occlusion device 2 C also includes the ring 46 which is the same as the ring 46 described above. The aortic occlusion device 2 C may be manufactured in any manner such as the manner described above or as a simple extrusion or laminated structure.

Referring to FIG. 16 , the aortic occlusion device 2 is shown passing through a side port 112 of a cannula 28 D. The side port 112 facilitates positioning the occluding member 4 in the ascending aorta. The aortic occlusion device 2 is preferably the aortic occlusion device 2 described above. The aortic occlusion device 2 passes through a lumen 114 in the cannula 28 D. The lumen 114 is coupled to the source of oxygenated blood 72 so that the oxygenated blood is delivered through the annular area between the aortic occlusion device 2 and the wall of the lumen 114 . The lumen 114 has an open end 116 with a cross-member 118 which prevents the aortic occlusion catheter 2 from passing through the open end 116 . An advantage of the side port 112 is that the aortic occlusion device 2 is directed into the ascending aorta while blood passing through the lumen 114 is directed in the direction of normal blood flow in the aorta.

Referring to FIGS. 18 and 19 , another aortic occlusion device 2 E is shown. The aortic occlusion device 2 E is similar to the aortic occlusion device 2 A of FIG. 13 in that balloon 130 is inflated with oxygenated blood delivered from the source of oxygenated blood 72 . Oxygenated blood is delivered to the patient through a lumen 132 and an open end 134 of the aortic occlusion device 2 E. As will be described below, the interior of the balloon 130 is fluidly coupled to the lumen 132 through an inflation hole 133 for inflating the balloon 130 when blood is delivered through the lumen 132 .

The aortic occlusion device 2 E includes a body 136 having the y-arm connector 30 described above. A sleeve 138 is positioned in the lumen 132 to control inflation and deflation of the balloon 130 . Blood passing through the lumen 132 passes through the sleeve 138 so that the sleeve 138 does not interfere with delivery of oxygenated blood to the patient. The sleeve 138 is attached to a rod 140 which is manipulated to move the sleeve 138 between the positions of FIGS. 18 and 19 . The sleeve 138 has a hole 142 which is aligned with the inflation hole 133 as shown in FIG. 18 to fluidly couple the interior of the balloon 130 with the lumen 132 . When the sleeve 138 is advanced to the position of FIG. 19 , the hole 142 is not aligned with the inflation lumen 133 and the sleeve 138 covers the inflation hole 133 so that the interior of the balloon 130 is not fluidly coupled to the lumen 132 .

The sleeve 138 permits the surgeon to control inflation and deflation of the balloon 130 . After introduction of the aortic occlusion device 2 E, bypass support is generally initiated before inflating the balloon 130 . This can be accomplished by maintaining the sleeve 138 in the position of FIG. 19 so that the balloon 130 is not inflated by the blood delivered through the lumen 132 . When it is desired to inflate the balloon 130 and occlude the ascending aorta, the sleeve 138 is moved to the position of FIG. 18 so that the balloon 130 is inflated with blood. The sleeve 138 also permits the surgeon to maintain full occlusion of the ascending aorta even when blood flow is reduced to a level which would not provide sufficient pressure to inflate the balloon to maintain full occlusion of the aorta. In order to maintain occlusion at low flow rates, the sleeve 138 is moved to the position of FIG. 19 before reducing the blood flow rate so that the balloon 130 will remain inflated when the delivery pressure drops. Finally, the sleeve 138 also permits the surgeon to maintain bypass support with a deflated balloon 130 after the surgical procedure is completed. In order to maintain deflation of the balloon while delivering blood, the blood flow rate is reduced to deflate the balloon 130 , the sleeve is moved to the position of FIG. 19 to deflate the balloon, and the blood flow rate is then increased. The sleeve 138 prevents the balloon 130 from inflating when the blood flow rate is increased.

The body 136 may be made in any suitable manner and is preferably manufactured similar to the cannula 28 of FIG. 6. A support tube 144 is attached to the body and the balloon 130 is mounted to the support tube. A soft tip 145 is attached to the distal end of the support tube 144 to provide an a traumatic distal end to prevent injury during introduction of the device 2 E. The sleeve 138 may be made of any suitable material and is preferably a urethane tube. The rod 140 may also be made of any suitable material and is preferably urethane coated polyamide. Although it is preferred to provide the sleeve 138 between the interior of the balloon 130 and the lumen 132 any other device may be used such as a valve, balloon or plug.

Use of the cannula and aortic occlusion device 2 is now described in connection with FIGS. 12 and 17 . The description below is applicable to all cannulae 28 , 28 D and aortic occlusion devices 2 , 2 A, 2 B, 2 C described herein. Although the method described below is for direct insertion of the cannula 28 and aortic occlusion device 2 into the aortic arch, the cannula 28 and aortic occlusion device 2 may also be introduced through a peripheral artery such as the femoral, subclavian or axillary arteries as described in U.S. Pat. No. 5,484,803.

Before introduction of the cannula, a rib retractor 120 or other device is used to form an opening in an intercostal space such as the 4 th intercostal space. The opening through the intercostal space is used for access to perform a surgical procedure such as a valve repair or replacement. The opening also provides direct access to the ascending aorta for control of the ascending aorta and to place purse-string sutures in the aorta.

An incision is also created in the 1 st or 2 nd intercostal space in which an 11.5 mm trocar 122 is positioned. The cannula 28 is then introduced through the trocar 122 and advanced to the surface of the aorta with the introducer 50 (see FIGS. 10 and 11 ) positioned in the lumen 35 of the cannula 28 to determine the appropriate orientation of the cannula 28 . The distal end of the introducer 50 is then moved into contact with the aorta about 1-2 cm below the origin of the innominate artery to identify the appropriate location for purse-string sutures 124 . The surgeon then places two purse-string sutures 124 around the site. The ends of the purse-string sutures 124 are passed through tubes 126 which are used to tension the purse-string sutures 124 . The purse-string sutures 124 are then passed through the slots 48 in the ring 46 .

The cannula 28 is then advanced into contact with the aorta at the site now surrounded by the purse-string sutures 124 . The surgeon then incises the aorta with the incising element 52 of the introducer 50 or with a separate incising instrument. The cannula 28 is then immediately advanced through the incision until the ring 46 engages the aorta. The radiopaque marker 45 may be viewed under fluoroscopy and the cannula 28 manipulated until the beveled tip is directed toward the aortic valve. Alternatively, the tip orientation may be determined by TEE. The purse-string 124 sutures are then tensioned to seal around the cannula 28 . The aortic occlusion device 2 is then passed through the hemostasis valve 36 and advanced until the occluding member 4 is positioned in the ascending aorta. Delivery of oxygenated blood, occlusion of the ascending aorta and delivery of cardioplegic fluid is then performed in the manner described in U.S. Pat. No. 5,484,803.

Although the method described above positions the aortic occlusion device through an opening separate from the opening through which the surgeon operates, the cannula and aortic occlusion device 2 may also be introduced through the same opening through which the surgeon operates. The choice of opening location, number and size are a matter of surgical choice depending upon patient anatomy, the medical procedure being performed, surgeon preference and the particular embodiment of the invention being used. Furthermore, the devices described herein may have application in other parts of the heart and in other parts of the body. Thus, the description of the specific procedure described above is merely an example and other surgical methods may be used with the devices and methods of the present invention.

Claims

1. A system for occluding a patient's ascending aorta and delivering oxygenated blood to the patient, comprising:a cannula having a first lumen and a second lumen, the first lumen having a distal end for delivering oxygenated blood; an occluding member mounted to one side of the cannula at a location proximal the distal end, the occluding member being movable between a collapsed position and an expanded position, the occluding member having a pathway therethrough in fluid communication with the second lumen, wherein the occluding member is a balloon.

2. The system of claim 1, wherein the occluding member is configured to occlude the aorta at a location between the barchiocephalic arteries and the coronary ostia.

3. The system of claim 2, wherein the occluding member is configured such that the cannula is located between the occluding member and the brachiocephalic arteries when the occluding member occludes the aorta at a location between the brachiocephalic arteries and the coronary ostia.

4. The system of claim 1, wherein the cannula has a third lumen in fluid communication with the interior of the occluding member.

5. The system of claim 4, comprising a source of cardioplegia fluid coupled to the second lumen.

6. The system of claim 1, comprising a source of oxygenated blood coupled to the first lumen.

7. The system of claim 1, wherein the distal end of the cannula has side ports.