Abstract:
A catheter delivered device to close a septal defect, the device comprising a cylindrical shaft of metal or polymeric material with concentric parallel cuts through the wall of the device which create flattened support struts. The center of the support struts move radially away from the axis in a hinge like fashion in response to the movement of the device&#39;s proximal and distal ends toward the center of the device. This movement is reversibly effected through mechanical means. The device can be coated with growth factors, mitogenic factors or other determinants which can improve tissue growth such that tissue ingrowth can occur over a period of time. The catheter itself may be an ultrasonic imaging catheter.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of Ser. No. 09/218,381 filed Dec. 22, 1998, U.S. Pat. No. 6,117,159 is a continuation of U.S. patent application Ser. No. 08/935,524 filed Sep. 23, 1997, now U.S. Pat. No. 5,853,422 which is a File Wrapper Continuation of U.S. application Ser. No. 08/620,286 filed Mar. 22, 1996 (now abandoned), both of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to the closure of intravascular defects and more specifically to a device for closing a septal defect, the device being delivered to the site of the defect by a catheter and comprising a metallic or polymeric material which is adjusted by mechanical means to a configuration which functions as a plug. 
     2. General Background 
     The heart is divided into four chambers, the two upper being the left and right atria and the two lower being the left and right ventricles. The atria are separated from each other by a muscular wall, the interatrial septum, and the ventricles by the interventricular septum. 
     Either congenitally or by acquisition, abnormal openings, holes or shunts can occur between the chambers of the heart or the great vessels (interatrial and interventricular septal defects or patent ductus arteriosus and aorthico-pulmonary window respectively), causing shunting of blood through the opening. The ductus arteriosus is the prenatal canal between the pulmonary artery and the aortic arch which normally closes soon after birth. The deformity is usually congenital, resulting from a failure of completion of the formation of the septum, or wall, between the two sides during fetal life when the heart forms from a folded tube into a four-chambered, two unit system. 
     These deformities can carry significant sequelae. For example, with an atrial septal defect, blood is shunted from the left atrium of the heart to the right, producing an over-load of the right heart. In addition to left-to-right shunts such as occur in patent ductus arteriosus from the aorta to the pulmonary artery, the left side of the heart has to work harder because some of the blood which it pumps will recirculate through the lungs instead of going out to the rest of the body. The ill effects of these lesions usually cause added strain on the heart with ultimate failure if not corrected. 
     Previous extracardiac (outside the heart) or intracardiac septal defects have required relatively extensive surgical techniques for correction. To date the most common method of closing intracardiac shunts, such as atrial-septal defects and ventricular-septal defects, entails the relatively drastic technique of open-heart surgery, requiring opening the chest or sternum and diverting the blood from the heart with the use of a cardiopulmonary bypass. The heart is then opened, the defect is sewn shut by direct suturing with or without a patch of synthetic material (usually of Dacron, teflon, silk, nylon or pericardium), and then the heart is closed. The patient is then taken off the cardiopulmonary bypass machine, and then the chest is closed. 
     In place of direct suturing, closures of interauricular septal defects by means of a mechanical prosthesis have been disclosed. 
     U.S. Pat. No. 3,874,388 to King et al. relates to a shunt defect closure system including a pair of opposed umbrella-like elements locked together in a face to face relationship and delivered by means of a catheter, whereby a defect is closed. U.S. Pat. No. 5,350,399 to Erlebacher et al. relates to a percutaneous arterial puncture seal device also including a pair of opposed umbrella-like elements and an insertion tool. 
     U.S. Pat. No. 4,710,192 to Liotta et al. relates to a vaulted diaphragm for occlusion in a descending thoracic aorta. 
     U.S. Pat. No. 5,108,420 to Marks relates to an aperture occlusion device consisting of a wire having an elongated configuration for delivery to the aperture, and a preprogrammed configuration including occlusion forming wire segments on each side of the aperture. 
     U.S. Pat. No. 4,007,743 to Blake relates to an opening mechanism for umbrella-like intravascular shunt defect closure device having foldable flat ring sections which extend between pivotable struts when the device is expanded and fold between the struts when the device is collapsed. 
     U.S. Pat. No. 4,699,611 to Bowden relates to a biliary stent having radially protruding lobes. 
     There still exists a need, however, for a simple mechanical method of closing septal defects, either temporarily or permanently, with an improved plug having a unitary construction that i s adjusted by mechanical means from a delivery configuration to a configuration which functions as a plug at the site of a defect. 
     SUMMARY OF THE INVENTION 
     The present invention provides devices and method for closing off, restricting the blood flow through or plugging a septal defect, the devices being made of metallic or polymeric materials in specific conformations which are delivered to the area of defect by a catheter means and adjusted by mechanical means to a configuration which functions as a plug or restriction. 
     The device may contact both sides of the septum thereby plugging the septal defect. 
     The septal defect closure device of the present invention may be used to close the ductus arteriosus, ventricular septum or atrial septum, or may even be used to block or fill an artery, vein or other vessel. 
     The device may be in any shape which is suitable for filling and plugging a defect. The defect may be contacted by the surface of the metallic material or polymeric material, which is biocompatible. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     FIG. 1 shows an anterior to posterior sectional view of a human heart, showing a typical atrial septal defect (ASD) prior to closure, and a typical ventricular septal defect (VSD) prior to closure by the device of the present invention; 
     FIG. 2 shows a side view of a septal defect closure device of the present invention in its delivery state; 
     FIG. 3 is a side view of the device of FIG. 2 in an intermediate conformation which it would assume after delivery and during its mechanical transformation into a plug; 
     FIG. 4 is a side view of the device as in FIG. 3 after its mechanical transformation into a plug; 
     FIGS. 5 a  and  5   b  are anterior to posterior sectional views showing the delivery and placement of the septal defect closure device of FIG. 2; 
     FIG. 6 is a sectional view of an alternative embodiment of a device according to the present invention; 
     FIG. 7 is a sectional view thereof taken along line  7 — 7  in FIG. 6; 
     FIG  8  is a sectional view thereof taken along line  8 — 8  in FIG. 6; 
     FIG. 9 is a view similar to that of FIG. 6 showing an alternative view thereof; 
     FIG. 10 is a sectional view thereof taken along line  10 — 10  in FIG. 9; 
     FIG. 11 is a perspective view of an intralumen mechanical mechanism thereof; 
     FIG. 12 is a perspective view thereof; 
     FIG. 13 is a perspective view of an alternative embodiment of the intralumen mechanical mechanism thereof; 
     FIGS. 14-15 respectively show a perspective view of an alternative embodiment of a device according to the present invention and a pull mechanism whereby the device is transformed into a plug; 
     FIGS. 16-17 show a sectional view of the device of FIG. 14 including a pin locking mechanism; 
     FIG. 18 is a perspective view of the invention with deployment catheter; 
     FIG. 19 is a perspective view of an alternative embodiment thereof; 
     FIG. 20 is a perspective view of an alternative embodiment thereof; 
     FIGS. 21-22 show a sectional view of the device as in FIGS. 14,  16  and  17  further including a plurality of tissue hooks; 
     FIGS. 23-24 show side views of a device as shown in FIGS. 3-4 respectively, the device further including a plurality of tissue hooks, FIG. 23 showing an intermediate conformation which the device would assume after delivery and during its mechanical transformation into a plug, FIG. 24 showing a side view of the device as in FIG. 23 after its mechanical transformation into a plug, and 
     FIG. 25 is an anterior to posterior sectional view showing the septal defect closure device of FIGS. 23-24 after delivery to the atrial and ventricular defects as depicted therein. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention provides an apparatus and method of closing off restricting the blood flow therethrough or plugging a septal defect. The apparatus comprises a catheter delivered device to close a septal defect, the device comprising a hollow shaft with cuts or grooves in the wall of the device which create deformable hinged support struts. The shaft may have a circular cross section. The device may suitably be made of any biocompatible material. Alternatively the device could be made of a non-biocompatible material with a suitable biocompatible coating. 
     The device of the present invention may be made of any suitable polymeric material including but not limited to polycarbonate urethanes, polyamides, polyether urethanes, polyethylene terephthalate (PET), polybutylene terephthalate, polyethylenes, high density polyethylene, polyimides, epoxides, composites of collagen and PET, composites of high strength carbon fiber and PET and composites of PET or carbon fibers within epoxides. Any thermosets, thermoplastics, thermoplastic elastomers, elastomers, composites, pseudo-thermoplastics, carbohydrates, proteins, or mixtures thereof may suitably be used. In addition to synthetic polymers portions of the device could be constructed of natural materials as collagen I or III, or IV or of glycosaminoglycans as chondroitin sulfate or composites thereof. 
     The device may alternatively be made of a metallic material. Examples of suitable metallic materials include stainless steel, spring steel, memory shape metals (such as nitinol), titanium, and metal alloys of any kind not limited to the aforementioned. Furthermore, the configuration of the metal device may be solid, braided or woven. 
     The device may alternatively be made of carbon fiber composites coated with any of the prior cited polymeric materials or of metal fibers coated with polymeric materials. The device may be completely or partially coated with polymeric materials. The apparatus may also be comprised of metal substrates coated with polymer which is in turn coated with natural materials. 
     Referring now to the Figures, FIG. 1 is a sectional view of a human heart showing defects in septal tissue, a typical atrial septal defect (ASD)  6  and a typical ventricular septal defect (VSD)  6 ′, prior to closure. The defects are shown together for illustrative purposes only, not as a depiction of multiple septal defects. However, multiple defects may be present. Apparent in the figure are left ventricle  50 , left atrium  56 , right ventricle  58 , right atrium  60 , mitral valve  54 , tricuspid valve  66 , inferior vena cava  62  and superior vena cava  64 . 
     As shown in FIG. 2, the catheter delivered device, shown generally at  10 , comprises a cylindrical shaft  12  having a proximal end  14 , a distal end  16 , and a central portion  18 . Cylindrical shaft  12  has parallel cuts  20  therethrough, which as shown in FIGS. 3-5, create support struts  22 . The cuts could also be helical or serpentine. The struts could be covered by a cloth or other covering. 
     As shown in FIGS. 2-4,  5   a  and  5   b , hinge point  24  of support struts  22  move radially away from the axis of the device in a hinge like fashion in response to the movement of proximal and distal ends  14 ,  16  toward the central portion  18  of the device  10 . The hinge point  24  could be formed in a variety of ways. It could be a mechanical hinge, a thinned section created by chemical etching, mechanical denting, grinding, heat forming or machining, a weakened section created by micro cuts, tapered grooves ( 20 ), chemical treatment, or any other process which will cause a preferential stress point. 
     As shown in FIGS. 4,  5   a  and  5   b , the device will assume a plug like formation when in place, whereby device  10  will span both sides of the septal defect. Device  10  will be anchored to the tissue of the septal defect by the physical interaction such as pressure from struts  22 . The septal defect closure device may further comprise a plurality of tissue hooks located thereon to anchor the device in place in the septal defect. 
     The delivery and placement of device  10  in a septal defect is illustrated in FIGS. 5 a  and  5   b , which depict placement of the device and removal of delivery catheter  40 . Like FIG. 1, FIG. 5 a  and  5   b  depict defects  6 , 6 ′ of both atrial septal tissue and ventricular septal tissue, respectively. 
     The route by which the cardiac defects are accessed via catheter are described as follows. An ASD or VSD may be accessed from the arterial circuit, as shown in FIG. 5 a . The catheter/device is introduced into the arterial vascular system and guided up the descending thoracic and/or abdominal aorta. The device may then be advanced into the left ventricle (LV)  50  through the aortic outflow tract. Once in LV  50 , the device may be deployed in VSD  6 ′. Alternatively, once in LV  50 , the device may be directed up through mitral valve  54  and into the left atrium (LA)  56 . When the device is in LA  56 , it may be directed into ASD  6  and installed. In FIG. 5 b , device  10  is shown already in place in ASD  6  with catheter/delivery means  40  in the process of being withdrawn. Device  10 ′ is shown being placed in VSD  6 ′. Device  10 ′ is delivered to the area of septal defect  6 ′ by catheter  40  and inserted in place, centered in septal defect  6 ′ as shown in FIG. 5 a . Device  10 ′ may be either pulled or pushed out of catheter  40 ′ and installed in a manner set forth more fully hereinbelow. After installation, device  10 ′ will assume its preform shape in a narrow center portion with enlarged ends. Device  10  is shown in place closing off atrial septal defect  6 , as catheter delivery means  40  is being withdrawn. 
     Alternatively, an ASD or VSD may be accessed from the venous circuit, as shown in FIG. 5 b . The catheter/device may be introduced into the venous system, advanced into Inferior Vena Cava (IVC)  62  or Superior Vera Cava (SVC)  64  and guided into the right atrium (RA)  60 . The device may then be directed into ASD  6 . 
     Alternatively, once in RA  60 , device  10  may be advanced through tricuspid valve  66  into the right ventricle (RV)  58  and directed into VSD  6 ′ and installed. In FIG. 5 b , device  10  is shown being placed in ASD  6 . Device  10 ′ is shown already in place in VSD  6 ′ with catheter  40 ′ in the process of being withdrawn. Device  10  is delivered to the area of septal defect  6  by catheter  40  and inserted in place, centered in septal defect  6  as shown in FIG. 5 b . Device  10  is shown in place closing off ventricular septal defect  6 ′, as catheter delivery means  40 ′ is being withdrawn. 
     An alternative embodiment is shown in FIGS. 6-10. FIG. 6 is a cross-section of the device, indicated generally at  100 . Device  100  has an interior portion  110 , an exterior portion  112 , proximal and distal ends  114 ,  116  and a center portion  118 . Distal end  116  of device  100  is closed to block blood flow through its interior  110 . Proximal end  114  has an opening  120  which provides access to interior  110 . Arrow head  122  extends proximally from distal end  116  into interior  110 . Lock  124  extends distally from opening  120  at proximal end  114  into interior  110 , and is shaped to mate with arrow head  122 . Arrow head  122  fits or snaps into lock  124  when distal end  116  is pulled toward proximal end  114 . Lock  124  has a proximal undercut  126  shaped to mate with central barbs  128 , which are located in the central portion  118  of interior  110 . Proximal undercut  126  snaps onto central barbs  128  when proximal end  114  is pulled towards center  118 . 
     Device  100  may be reversibly locked in place by means of an intralumen mechanical mechanism or twist-lok mechanism  140  (best seen at FIGS.  11  and  13 ). Both distal end  116  and proximal end  114  have twist-lok tracks, proximal  130  and distal  132 . Cross sections of proximal twist-lok track  130  and distal twist-lok track  132  are shown at FIGS. 7 and 8, respectively. Proximal twist-lok track  130  is shown at FIG. 7 with twist-Lok mechanism  140  at resting/delivery position. Twist-lok mechanism  140  comprises a hollow outer shaft  146  with proximal twist-lok means  142  attached thereto and an inner shaft  148  having distal twist-lok means  144  attached thereto. As shown in FIG. 11, twist-lok means  142 ,  144  may be T-shaped. Twist-lok means  142 ,  144  may alternatively be star-shaped, as shown in FIG.  13 . Twist-lok mechanism  140  may have twist-lok means of any other shape that will provide linear movement and permit locking and unlocking of the delivery means from device  100 . 
     Twist-lok mechanism  140  is constructed and arranged to pull ends  114 ,  116  toward center  118  of device  100 . Alternatively, this movement may be reversibly effected through any suitable mechanical means, such as screws, ratchet, snap fittings, or tie off procedures, all of which would prevent the device from opening up and resuming a cylindrical shape. 
     Referring to FIGS. 11-12, inner shaft  148  is rotatably mounted in outer shaft  146  to provide independent rotational movement of proximal and distal twist-lok means  142 ,  144 . Inner shaft  148  is also distally extensible from outer shaft  146 . 
     In operation, proximal twist-lok means  142  is rotated counter-clockwise to its resting/delivery position, and is rotated clockwise to un-lock. Distal twist-lok track  132  of device  100  is shown at FIG. 8 with distal twist-lok means  144  therein. The rotational directions of proximal and distal twist-lok means  142 ,  144  are opposite of each other, so that device  100  may not detach from the delivery system unless twist-lok means  142 ,  144  are rotated. 
     Subsequent removal of device  100  may be effected by inserting twist-lok mechanism  140  and rotating twist-lok means  142 ,  144  in their respective removal directions to recapture device  100  for un-deployal and removal. 
     FIGS. 10 and 12 show an optional anchoring means  150   a ,  150   b  which may be employed as a safety or reinforcement, anchoring means  150   a  being located at the proximal end  114  of device  100 , and anchoring means  150   b  being located at the distal end  160  of outer shaft  146  of twist-lok means  140 . To eliminate rotation, splines  152  located at proximal end  114  of device  100  interlock or press fit into ribs  154  located in the interior of outer shaft  146  of twist-lok means  140 . Distal movement of inner shaft  162  will push device  100  out of outer shaft  160 , disengaging splines  152  and ribs  154 ; shaft  148  will cause distal end  162  of inner shaft  148  of twist-lok means  140  to contact device  100 , pushing anchoring means  150   a  of device  100  away from anchoring means  150   b  and out of outer shaft  146  of twist-lok means  140 , disengaging splines  152 . Proximal and distal twist-lok bars  142 ,  144  are each capable of movement both distally and proximally depending on their current position, thus allowing for deploying and undeploying before releasing of device  100  altogether. 
     An alternative embodiment of the closure device according to the present invention is shown at FIGS. 14-17. FIG. 14 shows a perspective view of an alternative embodiment of a device according to the present invention. FIG. 15 shows a perspective view of a pull mechanism whereby the device is transformed into a plug. As shown in FIG. 14, the catheter delivered device, shown generally at  200 , comprises a cylindrical shaft  212  having a proximal end  214 , a distal end  216 , and a central portion  218 . Cylindrical shaft  212  has parallel struts  222 . Struts  222  may be covered by a cloth or other suitable biocompatible covering. 
     Pull mechanism  230  comprises shaft  231  with distal pull bar (or twist-lok bar)  232 , pull mechanism being constructed and arranged for invention into device  200  through proximal opening  233  and distally through distal opening  234 , and rotated as shown in FIGS. 16-17. In the position shown at FIGS. 16-17, pull mechanism  230  can pull distal end  216  toward center  218  and center  218  toward proximal end  214 . Alternatively, this movement may be reversibly effected through any suitable mechanical means, such as screws, ratchet, snap fittings, or tie off procedures, all of which would prevent the device  200  from opening up and resuming a cylindrical shape. 
     As shown in FIGS. 16-17, hinge points  225  move radially away from the axis of the device in a hinge like fashion in response to the movement of proximal and distal ends  214 ,  216  toward the central portion  218  of the device  200 . Hinge points  225  could be formed in a variety of ways. Such a hinge point could be a mechanical hinge, a thinned section created by chemical etching, mechanical denting, grinding, heat forming or machining, a weakened section created by micro cuts, tapered grooves, chemical treatment, or any other process which will cause a preferential stress point. 
     The embodiment shown in FIGS. 16-17 has three locking locations, center, proximal and distal. Distal end  216  may be locked to central portion  218  by means of distal locking pins  236  constructed and arranged to mate with central locking bores  240 , and proximal end  214  may be locked to central portion  218  by means of central locking pins  242  constructed and arranged to mate with proximal locking bores  238 . All mating locking surfaces preferably shaped in such a maner to facilitate locking. Locking pins  236 ,  242  may be ratcheted for the tightest fit. FIG. 17 is a partial view of device  200  showing the manner in which pins  236 ,  242  respectively lock into bores  238 ,  240 . 
     FIGS. 18-20 show deployment catheters with device  100  as shown in FIG.  6 . FIG. 18 shows deployment catheter  40  according to the present invention, with control means  300  located at proximal end  41  thereof. Control means  300  has linear slides  310 ,  312 , unlock lever  314  and flush port  316 . FIG. 19 shows catheter  40  with an alternative embodiment of control means  300 , having dual rotation knobs, i.e. proximal rotation knob  320  and distal rotation knob  322 . FIG. 20 shows a further alternative embodiment of deployment catheter  40 , having a gun-like handle  330  with up and down triggers  332 ,  334 , and un-lok slides  336 ,  338 . 
     The septal defect closure devices and apparatus disclosed herein may further comprise a plurality of tissue hooks located thereon to anchor the device in place in a septal defect. For example, FIGS. 21-22 show a sectional view of the device as in FIGS. 14,  16  and  17  further including a plurality of tissue hooks  270 . 
     FIGS. 23-24 show side views of a device as shown in FIGS. 3-4 respectively, the device further including a plurality of tissue hooks  70 . FIG. 23 shows an intermediate conformation which the device would assume after delivery and during its mechanical transformation into a plug. FIG. 24 is a side view of the device as in FIG. 23 after its mechanical transformation into a plug. FIG. 25 is an anterior to posterior sectional view showing the septal defect closure device of FIGS. 23-24 after delivery to the atrial and ventricular defects as depicted therein. Device  10  is anchored to the tissue of the septal defect by the physical interaction of the tissue hooks  70  therewith. 
     In a preferred embodiment, distal tip  42  of insertion catheter  40  according to the present invention is made of metal for visualization under fluoroscopy and is shaped in such a manner which does not interfere with the insertion of the twist-lok mechanism or pulling mechanism, fitting flushly with proximal end  14  of closure device  10 . 
     The entire closure device or the portion thereof exposed to the heart chambers may be covered or coated with a fabric and/or elastic material (not shown) which may be biodegradable. This material will block blood shunting across the septal defect and may also allow tissue ingrowth to help in the stabilization of the device. Fabrics with which the mid-section may be coated with are polyamides, such as nylon 6, nylon 6,6, and the like, polyesters, such as PET, polyethers, fluorinated polymers, such as polytetrafluoroethylene, or biodegradable or nonbiodegradable fibers derived from natural sources such as carbohydrates, collagens, and proteins. The fabric may be of a woven knit, or solid structure. 
     The unique features of the device are the manner of its deployment and its reversibility, its low profile which may prevent interference with normal heart functions, the shape of the support struts, and the non-invasive nature of the delivery which would reduce costs normally associated with closure of such a defect. The device may be made of metal or polymeric material and is delivered via catheter in a non-invasive procedure. The device operates through mechanical means to close a septal defect. 
     The practice of the present invention achieves several objectives and advantages. The device and method of the present invention provides an advantage over surgery in that the cost of the procedure is substantially less, the risk of infection is less, the hospital residency time is less and there is no physically deforming scar. 
     Advantages include the flexibility of the reversible deployment, the fact that the non-invasive delivery would reduce costs associated with this type of procedure, the low profile may prevent interference with normal heart functions. Support arms have three support locations which may provide increased support arm strength. 
     While this invention may be embodied in many different forms, there are described in detail herein specific preferred embodiments of the invention. This description is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiments illustrated. 
     The above Examples and disclosure are intended to be illustrative and not exhaustive. These examples and description will suggest many variations and alternatives to one of ordinary skill in this art. All these alternatives and variations are intended to be included within the scope of the attached claims. Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims attached hereto.