Patent Application
20060106420
This invention relates generally to medical devices and particularly to a device, system, and method for treating a septal defect such as a patent foramen ovale.
Fetuses have a normal opening, the foramen ovale, between the left and right atria of the heart. This opening allows blood to bypass the lungs while a child is in utero. The opening normally closes soon after a child is born and pulmonary circulation is established.
In some individuals, the foramen ovale fails to close (i.e., remains patent), resulting in a condition called patent foramen ovale (PFO). Many individuals with PFO experience no symptoms. However, PFO can lead to strokes when small, often undetectable, clots form in the pelvis or lower extremities. If a clot breaks loose, it can travel through veins to the heart and pass through the patent foramen ovale to the left (arterial) side of the heart. The clot may then travel with the arterial blood to the brain and become lodged there, preventing blood flow to a part of the brain, resulting in a stroke.
Other atrial and ventricular septal defects can occur and are commonly called “holes” in the heart. Most of these defects are congenital, but defects can occur rarely as a serious complication of a heart attack.
Septal defects may be repaired surgically. Although relatively simple, surgical therapy is invasive, costly, and painful, and is associated with all the usual risks of cardiac surgery.
Catheter-based treatment is also possible. In the case of PFO, treatment may involve stapling the foramen ovale closed. This method of treatment requires flaps of tissue that overlap sufficiently to effect closure of an opening when the flaps are stapled together. While flaps are usually present in PFO, the foramen ovale typically being a tunnel with openings that are not opposite each other but instead are displaced longitudinally, the longitudinal displacement may not be adequate to allow a staple device to pass through both flaps simultaneously, resulting in the staple passing through only the nearest flap and not engaging the second flap.
Even where the overlap is adequate for stapling, a certain amount of force may be required to ensure that a device passes through both flaps, and the device may need to be relatively long and/or remain in a fully open or straight position for some time before engaging the second flap. For best closure, the staple may need to pass entirely through both flaps, thus extending into the left atrium, which may pose a risk of embolus formation.
Another disadvantage of such systems is that the staples are typically ejected from a delivery catheter rather than having a controlled delivery. If the opening is inadequately closed by the staple, using a second staple may not be possible or desirable, resulting in the need for surgical closure of the PFO.
Therefore, it would be desirable to have a device, system, and method for treating a septal defect that overcomes the aforementioned and other disadvantages.
One aspect according to the present invention is a device for treating a septal defect, comprising a support and a patch attached to the support. The support includes a body segment and a plurality of flexible leg segments. The leg segments self-expand radially outward from the body segment as the support is released from a delivery catheter.
Another aspect according to the present invention is a system for treating a septal defect comprising a delivery catheter and a treatment device slidably received within a lumen of the delivery catheter. The treatment device has a support and a patch attached to the support. The support includes a body segment and a plurality of flexible leg segments. The leg segments self-expand radially outward from the body segment as the device is released from the delivery catheter.
Yet another aspect according to the present invention is an indwelling medical system comprising an elongated member, an anchor, and a retractable sheath. A portion of the elongated member is encircled by the anchor, which includes a body segment and a plurality of flexible leg segments. The retractable sheath encloses the flexible leg segments. At least a plurality of the flexible leg segments self-expand radially outward from the body segment when the sheath is retracted.
Still another aspect according to the present invention is a method of treating a septal defect. A treatment device is delivered in a lumen of a catheter proximate a septal defect. The treatment device has a support and a patch attached to the support. The support includes a body segment and a plurality of flexible leg segments. The treatment device is slid in a distal direction such that a portion of each leg segment is released from the distal end of the catheter and the leg segments are partially expanded radially outward from the body segment. As used herein, the terms “distal” and “proximal” are with reference to the treating clinician during deployment of the device. The treatment device is positioned such that the leg segments contact tissue surrounding the septal defect. The treatment device is again slid in a distal direction such that each leg segment is fully released from the distal end of the catheter and the leg segments are fully expanded radially outward from the body segment. In response to the full radial expansion of the leg segments, a distal portion of each leg segment is implanted in the tissue surrounding the septal defect, thereby positioning the patch against the septal defect.
The aforementioned and other features and advantages of the invention will become further apparent from the following detailed description, read in conjunction with the accompanying drawings, which are not to scale.
One aspect according to the present invention is a device for treating a septal defect. One embodiment of the device, in accordance with the present invention, is illustrated in
In the present embodiment, support 110 comprises a section of tubing having evenly spaced longitudinal slots cut into an end portion of the tubing to form body segment 112 and six flexible leg segments 114. One skilled in the art will appreciate that the number and shape of the leg segments may be varied. The slots may be, for example, rectangular, v-shaped, u-shaped, or Ω-shaped (omega-shaped). In another embodiment, support 110 may be manufactured by cutting, stamping, or otherwise forming the device from material not previously shaped into a tube. In either embodiment, the leg portions may be formed separately from the body portion of the contracting device and assembled to create an integral whole.
Support 110 is manufactured using one or more materials. At least leg segments 114 of support 110 comprise a material capable of being preset into a desired shape, for example that shown in
During manufacture, leg segments 114 are bent outward and heat set or otherwise set such that each of the leg segments is self-expanding radially outward at an angle of between 60 and 100 degrees from the longitudinal axis of body portion 112 when the treatment device is released from a delivery catheter. Leg segments 114 are in a radially compressed, folded configuration while device 100 is within the delivery catheter. As support 110 is released from the delivery catheter, leg segments 114 resume their preset shape, self-expanding radially outward from body segment 112. When the device is released adjacent to a septal defect, this radial expansion along with the force keeping the delivery catheter adjacent the septal defect implants a distal portion of each leg segment into tissue surrounding a septal defect. The leg segments are preferably implanted between the surfaces of the septal wall but may also pass through the tissue, piercing the septal wall.
To increase the ability of leg segments 114 to grip the tissue surrounding a septal defect, one or more barbs 116 may be formed on or adjacent to the distal tip of each leg segment as seen in
Each leg segment 114 may include an attachment structure 118 for attaching patch 120 to the underside of support 110 (i.e., to the side that faces away from body portion 112 when leg segments 114 are expanded.) In the present embodiment, the attachment structures are loops formed onto an edge of each leg segment. Other attachment structures are possible, for example hooks or notches. In the present embodiment, patch 120 is stitched to each attachment structure. A series of additional stitches may be spaced along each leg to securely attach patch 120 to support 110. In another embodiment, the patch may be attached to the support using other means of attachment, for example adhesive bonding or thermal bonding.
Patch 120 comprises one or more materials that physically block and/or encourage growth of tissue to block an opening in the septal wall. Appropriate materials include, but are not limited to, a bioabsorbable compound, a polyester fabric, a polyurethane fabric, a polyethylene terephthalate fabric (e.g., Dacron®), a biocompatible woven fabric, collagen, another biologic, a material capable of promoting tissue growth, combinations thereof, and the like. Patch 120 must be flexible enough to be compressed into a delivery configuration when device 100 is contained within a delivery catheter and to expand into a deployment configuration when leg segments 114 self-expand radially outward from body segment 112. When in its delivery configuration, patch 120 is folded or otherwise compressed and at least partially contained within leg segments 114. When fully expanded into its deployment configuration, patch 120 is substantially flat for positioning against the septal defect. Patch 120 is shown as a round, flat structure in
It is desirable that treatment device 100 be visible using intracardiac echocardiography (ICE), transesophogeal echocardiography (TEE), intravascular ultrasound, angioscopy, fluoroscopy, or another means of visualization to aid in positioning. Where fluoroscopy is utilized, any or all of treatment device 100 may be coated with a radiopaque material, or a radiopaque marker may be included on any portion of the device that would be useful to visualize.
Another aspect according to the present invention is a system for treating a septal defect. One embodiment of the system, in accordance with the present invention, is illustrated in
Delivery catheter 210 is a conventional catheter, as is known in the art. Catheter 210 has an appropriate inner diameter to deliver treatment device 220 to a treatment site. The length of catheter 210 may depend upon the delivery route.
Treatment device 220 comprises support 222 and patch 224. In the present embodiment, support 222 is a section of nitinol tubing having evenly spaced longitudinal slots cut into an end portion of the tubing to form body segment 221 and six flexible leg segments 223, as shown in
One skilled in the art will appreciate that the number of treatment device leg segments may be varied and that the support may be fabricated using other methods, including forming the support from one or more flat sheets of material. In addition, materials other than nitinol may be used, with at least leg segments 223 comprising a material capable of being preset into a desired shape. Such materials include, but are not limited to, a nickel-titanium alloy, a nickel-cobalt alloy, another cobalt alloy, a thermoset plastic, stainless steel, a stainless steel alloy, a biocompatible shape-memory material, a bioabsorbable shape-memory material, a biocompatible superelastic material, a bioabsorbable superelastic material, combinations thereof, and the like. Leg segments 223 are preset during manufacture into the radially expanded position they are to assume when deployed.
An antithrombotic component may be included in the chemical composition of a polymer used to form the device. Alternatively, a polymeric or metallic device may be coated with a polymer that releases an anticoagulant and thereby reduces the risk of thrombus formation. If desired, additional therapeutic agents or combinations of agents may be used, including antibiotics and anti-inflammatories.
Patch 224 comprises one or more materials that physically block and/or encourage growth of tissue to block an opening in the septal wall. Appropriate materials include, but are not limited to, a bioabsorbable compound, a polyester fabric, a polyurethane fabric, a polyethylene terephthalate fabric (e.g., Dacron®), a biocompatible woven fabric, collagen, another biologic, a material capable of promoting tissue growth, combinations thereof, and the like. Patch 224 must be flexible enough to assume both a compressed delivery configuration and an expanded deployment configuration. Each leg segment 223 may include an attachment structure 225 for attaching patch 224 to support 222.
Treatment device 220 is designed to be positioned using minimally invasive catheterization techniques. In
As described more fully below, treatment device 220 is preferably deployed in two stages. As shown in
In
Patch 224 expands into its deployment configuration when the leg segments self-expand. When fully expanded into its deployment configuration, patch 224 is substantially flat for positioning against the septal defect, as seen in
Treatment device 220 is deployed with the aid of elongated delivery device 230, which is slidably received within the lumen of catheter 210. In the present embodiment, delivery device 230 is a hypotube that is releasably attached to body segment 221 by means of connector 232. The outer surface of the treatment device body segment includes threads 226. Connector 232 is set onto the distal end of delivery device 230 and includes threads 236 on the inner surface of the connector that are complementary to the threads on body segment 221. Thus, treatment device 220 may be screwed onto delivery device 230 for delivery to and deployment at a treatment site and then unscrewed once the treatment device is fully deployed and ready to be released. A distal portion of the hypotube comprising delivery device 230 may include a spiral cut formed such that when delivery device 230 is rotated to disengage it from the fully deployed treatment device, the spiral tightens against itself rather than unwinding. The spiral cut increases flexibility of a distal portion of the delivery device without limiting transmission of torque to unscrew and release the treatment device.
One skilled in the art will appreciate that the treatment device body segment may have threads on an inside surface, and a connector having an outer diameter smaller than the inner diameter of the treatment device body may have threads on an outer surface. In another embodiment, the hypotube itself may include threads, eliminating the need for a connector. In yet another embodiment, neither the treatment device nor the delivery device may include threads, and the delivery device may be a length of hypotube that is not attached to treatment device 220. However, better control of delivery and deployment of the treatment device is possible if threads or other means of releasably attaching the treatment device to the delivery device are included.
Other delivery devices known in the art may be used. For example, in another embodiment, the delivery device may be biopsy forceps or another gripping device that holds the treatment device until it is properly positioned relative to the septal defect.
Stop 250 is shown in
In another embodiment, the stop(s) may be eliminated and an adaptor may be removably mounted on a proximal portion of the delivery catheter, the adaptor being movable between a first position in which the treatment device is fully within the lumen of the delivery catheter, a second position in which the treatment device is partially extended beyond a distal end of the delivery catheter, and a third position in which the treatment device is fully extended beyond the distal end of the delivery catheter. The adaptor may move amongst these positions using, for example, a ratcheting assembly or a thumb screw that contacts the delivery device to advance and retract it within the delivery catheter. In yet another embodiment, the body of the delivery device may simply include markings to indicate the Stage 1 and Stage 2 positions of the delivery device within the delivery catheter.
Delivery catheter 210 carrying treatment device 220 is passed through the venous system and into a patient's right atrium adjacent to the septal defect, in this embodiment a patent foramen ovale (PFO). Delivery may be accomplished as shown in
It is desirable that treatment device 220 be visible using intracardiac echocardiography (ICE), transesophogeal echocardiography (TEE), intravascular ultrasound, angioscopy, fluoroscopy, or another means of visualization to aid in positioning. Where fluoroscopy is utilized, any or all of treatment device 220 may be coated with a radiopaque material, or a radiopaque marker may be included on any portion of the device that would be useful to visualize.
As will be apparent to one skilled in the art, the support shown at 110 in
The aspect according to the present invention illustrated in
As illustrated in
Attachment structures 618 are positioned on body segment 612, rather than being on the leg segments as in previously described embodiments according to the present invention. Anchor 610 is attached to the outer surface of gastrostomy tube 620 using sutures that connect the attachment structures to the outer surface of the tube. In another embodiment, the attachment structures may be eliminated, and anchor 610 may be bonded to the outer surface of the gastrostomy tube using, for example, a biocompatible adhesive such as polyethylene oxide.
Anchor 610 and gastrostomy tube 620 are delivered to the stomach within delivery catheter 630. Leg segments 614 assume a radially compressed, folded configuration within catheter 630, which encloses the leg segments during delivery. The system is passed through the mouth, down the esophagus, and into the inner lumen of the stomach. The system may track down a guidewire and may include a piercing catheter for piercing through the stomach wall and the abdominal wall to the outside of the body. Alternatively, the opening to the outside of the body may be made using a trocar or other sharp instrument prior to introducing system 600 into the stomach lumen.
Anchor 610 may be deployed using a two-stage process similar to that described above. Tube 620 holds the placed anchor 610 in position against the wall of stomach 640 while delivery catheter 630 is retracted to deploy the anchor. As anchor 610 is released from the catheter, leg segments 614 resume their preset shape, self-expanding radially outward from body segment 612, penetrating into the gastric muscle layer and anchoring gastrostomy tube 620.
Anchor 710 encircles a portion of pacemaker lead 720 and is slidable along the lead until the anchor is fully deployed. The anchor includes a body segment 712 and a plurality of distal and proximal flexible leg segments, seen at 714 and 718, respectively. Proximal leg segments 718 serve as attachment members for fixing anchor 710 to lead 720 once the anchor is fully deployed.
Distal leg segments 714 are preset such that each of the leg segments is self-expanding radially outward at an angle of between 60 and 100 degrees from the longitudinal axis of body portion 712 when a retractable sheath, in this embodiment delivery catheter 730, is retracted. As shown in
Pacemaker lead 720 is delivered to its target position using techniques known in the art. Once the distal end of lead 720 has been conventionally attached within target zone 746, anchor 710 is positioned adjacent to coronary sinus ostium 742 and deployed using a two-stage process such as has been described above. An inner catheter may be used to hold anchor 710 in position as delivery catheter 730 is withdrawn to deploy the anchor. Leg segments 714 are implanted in tissue surrounding the coronary sinus ostium, anchoring the lead in the vein and reducing the risk of the lead being displaced over time.
Still another aspect according to the present invention is a method of treating a septal defect.
A treatment device is releasably attached to an elongated delivery device (Block 810). The treatment device comprises a support and a patch attached to the support. The support includes a body segment and a plurality of flexible leg segments. Treatment devices in accordance with the present invention are shown in
The delivery device and attached treatment device are positioned within a delivery catheter (Block 820). This may be accomplished by inserting the proximal end of the delivery device into the distal end of the delivery catheter, and feeding the delivery device and attached treatment device through the delivery catheter until the treatment device is drawn into the distal end of the delivery catheter as shown in
The treatment device is deployed in two stages. At Stage 1 deployment, shown in
One or more stops may be attached to a proximal portion of the delivery device to indicate when a deployment stage has been achieved. For example, the treatment device may be drawn into the catheter until it assumes the Stage 1 configuration. To mark this stage, a releasable stop, for example a wire torquing apparatus, may be attached to the delivery device and positioned abutting the proximal end of the catheter. The treatment device may then be drawn fully within the catheter, with the releasable stop drawn proximal to the end of the catheter and in position to indicate to the medical professional when Stage 1 deployment has been achieved. If desired, a stop indicating Stage 2 deployment may be similarly attached prior to attaching the Stage 1 deployment indicator.
It will be apparent to one skilled in the art that the stop(s) may be eliminated, and other means for achieving staged deployment may be employed. For example, the body of the delivery device may include markings that indicate the position of the delivery device within the delivery catheter at Stage 1 and Stage 2 deployment. Alternatively, an adaptor may be removably mounted on a proximal portion of the delivery catheter, the adaptor being movable between a first position in which the treatment device is fully within the lumen of the delivery catheter, a second position in which the treatment device is partially extended beyond a distal end of the delivery catheter (Stage 1 deployment), and a third position in which the treatment device is fully extended beyond the distal end of the delivery catheter (Stage 2 deployment). The adaptor may move amongst these positions using, for example, an assembly that contacts the delivery device to advance and retract it within the delivery catheter.
In another embodiment, the delivery device may be supplied already threaded into the delivery catheter, and the treatment device may be attached to the distal end of the delivery device and drawn into the delivery catheter as described above. In yet another embodiment, both the delivery device and the treatment device may be supplied already positioned within the delivery catheter.
The treatment device, fully contained within the lumen of the catheter, is delivered proximate a septal defect (Block 830). One path for delivering the treatment device is shown in
Once the treatment device is in place proximate the septal defect, the treatment device is slid in a distal direction such that a portion of each leg segment is released from the distal end of the catheter and the leg segments are partially expanded radially outward from the body segment (Block 840). The treatment device is positioned with the leg segments contacting tissue surrounding the septal defect (Block 850). The treatment device is slid farther in a distal direction until the leg segments are fully released from the distal end of the catheter and fully expanded radially outward from the body segment (Block 860). In response to the full radial expansion of the leg segments, a distal portion of each leg segment is implanted in tissue surrounding the septal defect, thereby positioning the patch against the septal defect (Block 870). The leg segments are preferably embedded within the septal wall (i.e., implanted between the surfaces of the tissue) but may also pass through the wall.
Once the leg segment distal portions have been implanted in the tissue, the treatment device is released from the delivery device (Block 880). In the present embodiment, this is accomplished by unscrewing the delivery device from the treatment device. The delivery catheter and delivery device may then be removed from the patient, leaving the treatment device in place with the patch positioned against the septal defect. The patch comprises one or more materials that physically block and/or encourage growth of tissue to block an opening in the septal wall, thereby treating a patent foramen ovale or other septal defect.
While specific embodiments have been disclosed, various changes and modifications can be made without departing from the spirit and scope of the invention. The scope of the invention is indicated in the appended claims, and all changes and modifications that come within the meaning and range of equivalents are intended to be embraced therein.
