US 20080312646 A9
The present invention provides for therapeutic treatment methods, devices, and systems for the partial or complete closure or occlusion of a patent foramen ovale (“PFO”). In particular, various methods, devices, and systems for joining or welding tissues, in order to therapeutically close a PFO are described. In yet another aspect of the invention, various methods, devices, and systems for the penetration of the interatrial septum enabling left atrial access are also provided.
1. A treatment method for closing a patent foramen ovale comprising two flap-like tissue structures and which is located on an interatrial septum separating a right and left atrium of a heart; said method comprising the steps of:
a) detecting and locating the patent foramen ovale;
b) encasing the two flap-like tissue structures between one or more heat generating members;
b) energizing the one or more heat generating means; and
c) applying a therapeutic amount of energy to join the two overlapping tissue structures at one or more positions of contact.
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15. A treatment method for therapeutically closing a patent foramen ovale on an interatrial septum separating a right and left atrium of the heart, said treatment method comprising the steps of:
a) determining the location of the patent foramen ovale; and
b) applying therapeutic amounts of energy to the septum at or near the location determined in step (a) to induce______.
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a) puncturing the septum on or near the patent foramen ovale and creating an access pathway into the left atrium of the heart.
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24. A catheter apparatus for closing a patent foramen ovale comprised of two overlapping tissue structures located on an interatrial septum which separates a right and left atrium of the heart, said apparatus comprising:
a) a means for locating and detecting the patent foramen ovale;
b) a means for puncturing the interatrial septum at, or adjacent, the patent foramen ovale; and
c) one or more means for transseptally delivering therapeutic amounts of energy one or more tissue locations in order to affect joining of the overlapping tissue structures.
25. The apparatus of
26. The apparatus of
A portion of this patent document contains material that is subject to copyright protection. The copyright owner does not object to the facsimile reproduction of the patent document as it appears in the U.S. Patent and Trademark Office patent file or records but otherwise reserves all copyright rights whatsoever.
The present invention relates generally to the field of cardiology, and in particular to methods, devices, and systems to close or occlude a patent foramen ovale or “PFO.”
A closed foramen ovale is formed after birth when two fetal structures, the septum secundum (“secundum”) and septum primum (“primum”), become fused and fibrose together. Usually, the fusion of these two anatomical structures occurs within the first two years of life ensuring the formation of a normal functioning heart. However, in about 25-27% of the general population, the secundum and the primum either do not fuse or the fusion is incomplete. As a result, a long tunnel-like opening will exist in the interatrial septum (“septum”) which allows communication between the right and left atrial chambers of the heart. This tunnel-like opening is a cardiac defect known as a PFO.
Normally, a PFO will be found near the fossa ovalis, an area of indentation on the right atrial side of the interatrial septum as illustrated in
Traditionally, open chest surgery was required to suture or ligate closed a PFO. However, these procedures carry high attendant risks such as postoperative infection, long patient recovery, and significant patient discomfort and trauma. Less invasive, or minimally invasive, treatments are preferred and are currently being developed.
To date, most of these non-invasive, or minimally invasive, procedures involve the transcatheter implantation of various mechanical devices to close or occlude a PFO. See
Yet another disadvantage of these mechanical devices is that the occlusion of the PFO is not instantaneous or complete immediately following implantation. Instead, occlusion and complete PFO closure requires subsequent endothelization of these devices. This endothelization process can be very gradual and can take several months or more to occur. Thus, “occlusion” of the PFO is not immediate but can be a rather slow and extended process.
Finally, the procedure to implant these devices can be technically complicated and cumbersome, requiring multiple attempts before the device can be appropriately and sufficiently delivered to the PFO. Accordingly, use of these devices may require long procedure times during which the patient must be kept under conscious sedation posing further risks to patients.
In light of these potentially serious drawbacks, new and improved non-invasive and/or minimally invasive methods, devices, and systems for the treatment of PFO, which either do not require the use of implantable devices or overcome some of the current shortcomings discussed above, are needed. The present invention meets these, as well as other, needs.
The present invention is directed to methods, devices, and systems for applying energy to join tissues, and in particular for joining the two flap-like tissues, the secundum and primum, that comprise a PFO. Tissues and blood in the human body demonstrate several unique properties when heated; accordingly heat can be used as an effective means for inducing the joining of tissues. Typically, when biological tissues and blood are heated, denaturation, melting, and/or coagulation of tissue and blood proteins, including collagen, takes place, along with the disruption of the cells and cellular walls, allowing intra-and-intercellular fluids and proteins to mix and form a type of “biological glue” which can be used to join tissues together. Yet another response to heat includes the activation of the body's healing mechanisms, which includes the activation of platelets, thrombin, fibrin, etc., and the formation of new scar tissue connections, which serve to join tissues.
A first aspect of the invention provides for methods, devices, and systems for joining tissue structures, and in particular, for joining the secundum and the primum to close or occlude a PFO. In accordance with this aspect of the invention, one method involves coapting the secundum and primum between one or more members and delivering therapeutic amounts of energy in order to join the two tissue structures together. As used herein, “coapt” means the drawing together of separated tissues or other structures. Energy sufficient to raise the native tissue temperatures of the coapted tissues to about 50°-100° C. is applied to the secundum and the primum. In accordance with this first aspect of the invention, various catheters for coapting and joining the primum and secundum are provided and further described herein.
In a second and related aspect of the invention, the primum and secundum are joined at one or more tissue contact sites, or alternatively are joined along a seam. Depending on the technique employed, complete or partial PFO closure can be selectively achieved. Described herein are possible implementations and configurations of heat generating members for creating: (1) a single tissue contact site; (2) a pattern of contact sites forming a seam; or (3) continuous seams having different shapes, for example, circular, curvilinear or straight seams.
A third aspect of the invention provides different methods, devices, and systems for ensuring tight joining of the tissues involving a welding technique. As used herein, “welding” refers to the use of heat in conjunction with pressure (as opposed to heat only) to join tissues together. Energy sufficient to raise the native tissue temperatures to about 50°-100° C. is applied in order to affect tissue welding of the secundum and the primum. Preferably, compressive force is used to not only coapt the primum and the secundum, but also to ensure the efficient and secure tissue welding during heating or energy delivery. To efficiently weld the primum and secundum, the two tissues should be encased between two opposed members that are provided as means to compress the tissues in question. Describe herein are methods and devices including various inflation members and other like devices for encasing, coapting, and compressing the tissue to be welded. As will be better understood in reference to the description provided below, one method for encasing the primum and the secundum between two opposed members is to transseptally deploy and position the two opposed members. As used herein “transseptal” means across or to the other side of the interatrial septum of the heart.
A fourth aspect involves various methods, devices, and systems for transseptally deploying various heating members, compressive members, or other like structures. In accordance with this aspect of the invention, one method involves puncturing the interatrial septum and a creating a passage therethrough so that one or more compressive members, heating members, or any combination thereof, which located at a distal working end of a PFO treatment catheter or catheter assembly, can be passed from one atrium of the heart to the other, preferably from the right to the left atrium.
A fifth aspect of the invention involves various medical kits comprising one or more catheters, puncturing means, guidewires, and/or other related components for therapeutically joining tissues or welding tissues in order to close or occlude a PFO in accordance with the present invention.
A sixth aspect of the invention involves various medical kits comprising one or more catheters, tissue penetrating devices, and other like means for transseptal penetration of the interatrial septum, thus allowing left atrial access. These devices and catheters embody various techniques and other aspects for easily identifying, positioning, and penetrating the septum at a pre-determined location.
A seventh aspect involves methods, devices, and systems for the deployment and implantation of various mechanical devices that represent an improvement over PFO occlusion devices and techniques currently known to those skilled in the art. In a related embodiment, these various devices and implants can be heated fixed or secured inside the patient.
A further aspect of the invention involves the various forms of energy that can be used to affect joining or welding of tissues, including, but not limited to: high intensity focused or unfocused ultrasound; direct heat; radiofrequency (RF); chemically induced heat (as in exothermic reactions), and other types of electromagnetic energy of differing frequencies, such as light (coherent and incoherent), laser, and microwaves can also be used. As described below, tissue heating in accordance with the present invention is char-free and controlled to prevent unintended thermal injury to the surrounding and adjacent cardiac tissues. One or more monitoring methods, devices (such as thermosensors), and systems are provided to ensure controlled and selective tissue heating.
Further understanding of the nature and advantages of the invention may be realized by reference to the remaining portions of the specification and the drawings.
FIGS. 14 generally illustrate yet another aspect of the present invention wherein the various PFO treatment catheters and device can be adapted with a location member designed to facilitate detection and location of a PFO, puncture location, as well as maintains the position of the PFO treatment catheter during the treatment process.
Referring now to the drawings, the flow chart of
PFO treatment catheter 21, in accordance with the present invention is illustrated in
PFO treatment catheter 21 can be used in conjunction with guidewire 31 so that it can be readily introduced and percutaneously advanced from the insertion site (such as a femoral vein, femoral artery, or other vascular access location) until distal working end 29 is appropriately seated within the patient's heart, at or near, PFO 1. In one possible implementation, guidewire 31 can be inserted into the femoral vein, advanced up the inferior or superior vena cava, into the right atrium and to the interatrial septum 3, near the fossa ovalis 10, and PFO 1.
Penetration of the interatrial septum 3 at a pre-determined location can be accomplished, with or without image guidance. Imagine guidance methods include but are by no means limited to: fluoroscopic; ultrasound (IVUS); intracardiac echo (ICE) ultrasound; magnetic resonance imaging (MRI); and echocardiographic guidance including transesophageal echocardiography (TEE). To penetrate and pass through interatrial septum 3, guidewire 31 can be removed and tissue penetrating device 41 advanced. In one embodiment of the present invention, tissue penetrating device 41 may be a puncturing needle such as conventionally available Brockenbrough needles or other like means. Another possible implementation involves the direct use of guidewire 31 to penetrate interatrial septum 3, eliminating the need to insert and advance separate tissue penetrating device or devices 41. In addition, various other transseptal penetrating methods and devices as disclosed in U.S. provisional applications: Serial No. 60/477,760, filed Feb. 13, 2003 and entitled “PFO and ASD Closure via Tissue Welding” and Serial No. 60/474,055, filed May 28, 2003 and entitled “Atrial Transseptal Atrial Access Technology;” the entire contents of which are hereby incorporated by reference and commonly assigned, can also be used to affect penetration of interatrial septum 3 to facilitate the transseptal passage of various devices, including the distal end of PFO treatment catheter 21, into the left atrium of the heart.
As illustrated in
In the present invention, various energies, energy delivery sources and devices can be employed to increase the native tissue temperatures within a therapeutic range between about 50°-100° C. including: (i) a radiofrequency (RF) generating source coupled to one or more RF electrodes; (ii) a coherent or incoherent source of light coupled to an optical fiber; (iii) a heated fluid coupled to a catheter with a closed channel configured to receive the heated fluid; (iv) a resistive heating source and heating element; (v) a microwave source coupled to a microwave antenna; (vi) an ultrasound power source coupled to an ultrasonic emitter or from external ultrasound; or (vii) any combination of the above. Tissue heating by any of these methods should be tightly controlled to ensure no charring and prevent overheating of the surrounding cardiac tissues. Accordingly, various known temperature sensing means, tissue impedance monitoring techniques, feedback systems, and controls may be incorporated into the present invention and to PFO treatment catheter 21 to allow monitoring of the heating process. Various cooling techniques can be employed (such as the seepage or circulation of various biocompatible liquids, saline, or blood during the heating process as a cooling mechanism). Moreover, such heating systems can be made to focus more energy on the right side of the septum, so that any emboli that are generated will not be allowed to enter the systemic circulation.
For ease of discussion and illustration, and for the remainder of this invention, use of RF energy, in a range of about 100-1000 kHz, supplying power in a range of about 5-50 watts, for duty cycles in a range of about 0.5-20 seconds, will be discussed. The various heat generating members described below are either monopolar or bipolar RF electrodes 53. However, all of the other energy sources and devices described above are equally applicable and may be incorporated into any of the embodiments provided below and used to affect the transseptal joining or welding of tissues to partially or completely, close or occlude, a PFO.
Turning now to
During use, guidewire 31 can be used to advance PFO treatment catheter 21 across and through interatrial septum 3 after interatrial septum 3 has been penetrated. Preferably, PFO treatment catheter 21 is advanced over guidewire 31 until distal inflation member 63 is located on the left atrial side of the interatrial septum 3 while proximal inflation member 61 is located on the right atrial side. To ensure this relative arrangement, these balloon structures 61, 63 can be inflated with contrast fluid, or one or more radio-opaque markers may be disposed on, or adjacent to, the inflation members, so that the desired transseptal positioning of the inflation members can be visually verified, for example, under fluoroscopy. After transseptal positioning of inflation members 61, 63 is visually verified, guidewire 31 may be removed and the tissue coapted together between proximal inflation 61 and distal inflation member 63. A simple method for coapting the tissues may be to expand the inflation members 61, 63 with a fluid (such as contrast solution); a gas (such as carbon dioxide), or any combination thereof. As shown in
Once coapted, the one or more RF electrodes 53 disposed on the surface of inflation members 61, 63 can be energized to heat the encased tissues and increase native tissue temperatures to about 500-100° C. In accordance with this aspect of the invention, RF electrodes 53 should be disposed on the surface of the inflations member 61, 63 so that when inflated, these RF electrodes 53 are in direct contact with the tissues to affect efficient tissue heating. RF electrodes 53 can be energized as many times as needed to affect sufficient tissue heating and subsequently heat induced joining of the tissues. As illustrated in
RF electrodes 53 can be disposed on the surface of proximal 61 and/or distal 63 inflation members using techniques including: ion implanting, electroplating, sputtering, electro-deposition and chemical and/or adhesive bonding methods; to disposed various RF electrodes 53 on the surface of the proximal 61 and distal 63 inflation members. Electrodes 53 may be formed from gold, platinum, silver, or other materials, preferably, these other materials should be malleable, suitable for in-vivo tissue contact, and thermally conductive.
To verify that a satisfactory level of closure or occlusion has been achieved, contrast TEE, ICE or TCD bubble studies can be performed before catheter is withdrawn from the patient through the passage created during penetration of interatrial septum 3. Preferably, the opening should be small enough so that the body's natural injury response mechanisms will serve to close this left atrial access pathway. PFO treatment catheter 21 can be used in conjunction with a guide or introducer sheath or catheter to facilitate advancement of catheter 21 into and through the tortuous vasculature.
In this aspect of the invention, joining or welding of the tissues may be affected at a single tissue contact point; at multiple tissue contacts points; or alternatively along a seam in order to affect partial or complete closure of the PFO tunnel. To this end, RF coils 71, 73 may be configured with one or more selectively spaced RF electrodes 71, 73 disposed on the coiled surfaces of RF coils 71, 73 in order to create the desired tissue contact point, pattern or seam given a pre-selected size and shape.
During operation, guide catheter 81 should be disposed on the right atrial side while the distal working end of inflation catheter 101 is transseptally passed through until inflation member 99 is located on the left atrial side. Various tissue penetrating devices 41, as well as guidewires 31, can be used to facilitate the transseptal advancement of the distal working end of inflation catheter 101 into the left atrium (as well as insertion and advancement of guide catheter 81 to the interatrial septum 3). Once appropriately advanced, inflation member 99 can be inflated to coapt and encase the secundum 5 and primum 7 between distal end 89 of guide catheter 81 and inflation member 99. In one embodiment of the invention, one or more RF electrodes 53 can be disposed on distal end 89 of guide catheter 81 and on inflation member 99 located on the inflation catheter so that bipolar RF energy may be used to join or weld the tissues. In another embodiment, one or more monopolar RF electrodes 53 can be disposed on distal end 89 of the guide catheter 81 and energized. Once the energy delivery is completed, inflation member 99 may be deflated, and with inflation catheter 91 and guide catheter 81, withdrawn from the patient.
As illustrated, the high intensity ultrasound catheter 111 is comprised of catheter shaft 113, first balloon 115, and gas-filled second balloon 117 located at distal working end of catheter 111. Comprised within first balloon 115 is gas filled inner “structural” balloon 121 and liquid filled outer “reflector” balloon 123, which is coaxially disposed around the inner structural balloon such that when both structural 121 and reflector 123 balloons are in a deflated configuration, reflector balloon 123 closely overlies deflated structural balloon 121. As shown in
In use, a high intensity ultrasound catheter 111 is positioned so that first balloon 115 is disposed within right atrium and second balloon 117 is disposed within the left atrium. Once appropriately positioned, first 115 and second 117 balloons may be inflated and the tissues to be joined or welded, coapted between first 115 and second 117 balloon. Ultrasound transducer 125 located within first balloon 115 is energized and acoustic energy projected forward into the tissues coapted between the two 115, 117 inflated balloons.
Because second balloon 117 is gas filled (and because high intensity acoustic waves cannot and do not travel well in gases) second balloon 117 functions to reflect any excess energy, preventing overheating in the left atrium and minimizing the risk of left side embolic events.
Briefly, the forward projection of acoustic energy from ultrasound transducer 125 into the coapted tissues is achieved by the configuration and shape of gas-filled structural balloon 121 and fluid filled reflector balloon 123 within first balloon 115, as described in more detail in U.S. Pat. No. 6,635,054. As described therein, gas-filled structural balloon 121 is comprised of active wall 127 which is formed from a flexible material and has a specific shape or configuration (parabolic or conical shape) when inflated. The shape of active wall 127, in conjunction with air-filled reflector balloon 123, functions to refract and project the acoustic waves 128 generated by the ultrasound transducer distally forward as illustrated in
As discussed above, sticking of heated tissues to the various heating elements 53, RF coils 71, 73, etc. should be avoided in those non-implant embodiments of the present invention. To this end, several techniques can be employed. For instance, various non-adhesive biocompatible gels, hydrogels, liquids (such as saline) may be employed to facilitate the release of the heated tissues from various PFO treatment catheters 21 of the present invention. Preferably, such materials are bio-absorbable. Also, these materials should be electrically conductive when used in conjunction with RF energy based components creating a complete electrical circuit. These materials may be disposed on the external surface of catheter 21 or extruded from one or more ports disposed at or near the distal ends of the various devices (coils 71, 73, balloons 61, 63) and catheters 21 of the present invention. In accordance with this aspect of the invention, inflation members 61, 63 may be formed of porous material in order to facilitate seepage of saline or other. like liquids to the tissues being heated. This seepage facilitates char-fee heating, ready release of tissues from the heating elements, and/or completion of the electrical circuit to enhance and promote the energy delivery process. In addition, circulation of these materials (as well as blood and/or other biological fluids) can also be provided as a means to promote cooling and heat dissipation during the energy delivery process to prevent issues of overheating, tissue charring, etc.
Detecting and locating PFO 1 is an important aspect of the invention and conventional techniques, including ultrasound, fluoroscopy, TEE, ICE, and ear oximetry techniques can be used for this purpose. In yet another embodiment, of the present invention the various catheters 21 of the present invention can be adaptively shaped to identify and engage certain detectable anatomical structures (such as the annular structure surrounding the fossa ovalis 10) as one means of locating PFO 1 as well as securely positioning PFO treatment catheters 21 and catheter assemblies 21 for penetration of interatrial septum 3 and the energy delivery process. In one embodiment, the various catheters 21 may be configured to further comprise location means 161 complementarily shaped to securely engage the antero-superior portion of the annular tissue structure 162 that typically surrounds the fossa ovalis 10 which is near PFO 1; or location means 161 may alternatively be used to locate the fossa ovalis 10. This aspect of the invention is illustrated in
In a further aspect of the present invention, the process of joining or welding of the tissues can be immediate leading to PFO 1 closure or occlusion following energy delivery in accordance with the present invention. However, it is also contemplated that joining or welding of the tissues can occur over several days wherein the tissue joining process is mediated in part to the body's healing response to thermal injury. Nevertheless, whether the closure or occlusion of the PFO is immediate or gradual, complete or partial; preferably, the attachment of the primum and secundum to affect PFO 1 closure or occlusion should be permanent.
Finally, while several particular embodiments of the present invention have been illustrated and described, it will be apparent to one of ordinary skill in the art that various modifications can be made to the present invention, including one aspect of one embodiment combined with another aspect of one embodiment. Other obvious adaptations of the present invention include the use of the devices, methods, and systems during minimally invasive surgery.
Also, as will be readily appreciated by those skilled in the art, the present invention described methods and devices that can be used to treat other types of cardiac defect. The general energy-based method for joining tissues is applicable as a therapeutic treatment method for closing other cardiac defects including, but not limited to patent ductus arteriosus, atrial septal defects, and other types of abnormal cardiac openings wherein an effective treatment is to join or weld tissue. Accordingly, the present invention and the claims are not limited merely for the therapeutic treatment of PFO but can be used for closure of occlusion of cardiac defects, body lumens, vessels, etc. Modifications and alterations can be made without departing from the scope and spirit of the present invention and accordingly, it is not intended that the invention be limited, except as by the appended claims.