WO2011066847A1

WO2011066847A1 - Catheter with emergency release

Info

Publication number: WO2011066847A1
Application number: PCT/EP2009/008650
Authority: WO
Inventors: Marcos Centola
Original assignee: Nvt Ag
Priority date: 2009-12-04
Filing date: 2009-12-04
Publication date: 2011-06-09
Also published as: DE112009005410T5

Abstract

The present invention concerns a catheter (10, 29) for deploying an endoluminal prosthesis (21) inside a body lumen (11), the catheter (10, 29) comprising a catheter shaft (13, 35) having arranged thereon said endoluminal prosthesis (21), and holding elements (22, 31) for securing, during deployment, said endoluminal prosthesis (21) to said catheter shaft (13, 35), which holding elements (22, 31) are releasably connected to the endoluminal prosthesis (21) and are connected to the catheter shaft (13, 35). Said holding elements (22, 31) are releasably connected to said catheter shaft (13, 35).

Description

Catheter with emergency release

[0001] The present invention relates to a catheter for deploying an endoluminal prosthesis inside a body lumen, the catheter comprising a catheter shaft having arranged thereon said endoluminal prosthesis, and holding elements for securing, during deployment, said endoluminal prosthesis to said catheter shaft, which holding elements are releasabiy connected to the endoluminal prosthesis and are connected to the catheter shaft.

[0002] Such catheters are extensively known from the art.

[0003] For example, US 2007/0203503 Al describes a catheter having a catheter shaft and a multitude of holding elements that are adapted for securing an endoluminal prosthesis to the catheter during deployment. [0004] WO 2009/038949 Al describes a catheter for delivering a prosthesis to a target treatment site, wherein the catheter and the prosthesis are coupled to each other by elements provided on the catheter, which elements, prior to and during deployment, releasably engage the prosthesis.

[0005] US 2007/0255386 Al describes a catheter with a threaded core member releasably engaging a threaded strut member provided on a self-expandable stent. The threaded strut member, upon release of the stent from the catheter, disengages from the threaded core member.

[0006] In such catheters, the engagement between catheter and endoluminal prosthesis, during deployment, serves the exact placement of the endoluminal prosthesis within the body lumen.

[0007] This exact placement is in most cases critical for the success of the operation and is difficult to achieve especially when placing endoluminal prostheses with large cross sections.

[0008] Such endoluminal prostheses with large cross sections may, for example, be stents or stent grafts to be deployed inside a major blood vessel such as the aorta. Moreover, in recent years, the transluminal placement of endoluminal valve prostheses, like endoluminal aortic valve prostheses, has become the preferred treatment for heart valve stenosis in many cases where open surgery for valve replacement is contraindicated by the critical health condition of the patient.

[0009] When compared to normal endoluminal prostheses, like stents, such endoluminal aortic valve prostheses, which have to be deployed within the native aortic valve of a patient, have a relatively wide cross section with respect to their length. The release of such endoluminal aortic valve prostheses from a conventional catheter can, owing to the large difference between compressed and original diameter of the endoluminal aortic valve prostheses, result in rapid radial expansion. This is insofar critical, as such rapid radial expansion may entail damage of the walls of the body lumen, for example the aortic walls, of the endoluminal prosthesis itself or the catheter.

[0010] Further, rapid radial expansion may cause misplacement of the endoluminal aortic valve prosthesis. Here, axial shift of the endoluminal aortic valve prosthesis or a tilt of the longitudinal axis of the endoluminal aortic valve prosthesis with respect to the longitudinal axis of the native heart valve may occur. In such cases, the operation is in most cases unsuccessful.

[0011] An additional problem, generally, is caused by foreshortening of endoluminal prostheses.

[0012] Because of their radial expansion, the majority of endoluminal prostheses, especially endoluminal prostheses with large diameters, shorten during deployment. This foreshortening increases the difficulty to place such endoluminal prostheses exactly.

[0013] For this reason, catheters for the deployment of endoluminal prostheses with large diameters often bear a multitude of holding elements that, on several points along the circumference of the endoluminal prosthesis to be deployed, releasably engage the endoluminal prosthesis; see for example US 2007/0203503 Al mentioned at the outset.

[0014] The holding elements are in this connection configured such that they counteract the rapid radial expansion of the endoluminal prosthesis by restricting the endoluminal prosthesis to, for example, an intermediate diameter. Hence, at least a significant part of the elastic tension exerted by the self-expanding endoluminal prosthesis is dissipated before the endoluminal prosthesis contacts the walls of the body lumen. Thus, after its release from the holding elements, the endoluminal prosthesis will expand gently. [0015] Further, the holding elements may comprise delivery bars engaging the endoluminal prosthesis, which delivery bars, upon deployment of the endolu- minal prosthesis become elastically deformed, bending in lateral directions towards the walls of the body lumen and, hence, absorbing elastic tension exerted by the self- expanding endoluminal prosthesis.

[0016] As the partially deployed endoluminal prosthesis still is releasably connected to the catheter, it can be shifted with respect to the longitudinal axis of the body lumen. Also, the releasable link to the catheter prevents the endoluminal prosthesis from being tilted with respect to the longitudinal axis of the body lumen to be treated.

[0017] After the endoluminal prosthesis is placed correctly and, for example, has been finally dilated with a dilation balloon in order to firmly engage the walls of the body lumen, the holding elements are released from the endoluminal prosthesis in an active or passive way.

[0018] A number of release mechanisms for such holding elements are described for example in US 2007/0203503 Al, WO 2009/038949A1 and US 2007/0255386 Al mentioned at the outset, the entire contents of these documents being incorporated herein by reference.

[0019] After successful release of the holding elements, the catheter is retracted.

[0020] The problem in this connection is that the release of the holding elements from the material of the endoluminal prosthesis occasionally is incomplete.

[0021] In these cases, not only the holding elements but also the catheter as a whole remains jammed inside the body lumen to be treated. [0022] In such situations, the only possibility to retrieve the catheter from, for example, the vasculature of the patient is open surgery.

[0023] On the premise that endoluminal and hence minimal-invasive treatments are primarily performed on older patients with severe co-morbid conditions, such open surgery is associated with a very high lethality rate.

[0024] In view of the above, it is an object of the present invention to improve the known catheters in such way that, despite the fact that jamming of holding elements may still occur, the catheters as such can still be retrieved from body lumen of the patient.

[0025] According to the present invention, this and other objects are achieved with a catheter of the kind mentioned at the outset, wherein said holding elements are releasably connected to said catheter shaft.

[0026] A "catheter", according to the invention, is an elongate device that can be inserted into a body lumen and can be used there to deploy an endoluminal prosthesis. In case the endoluminal prosthesis is self-expandable, which means that the endoluminal prosthesis expands without external force being exerted on it, the catheter usually comprises a constraining or cover sheath, covering the endoluminal prosthesis and keeping it radially compacted. Upon or during retraction of said cover sheath, said prosthesis expands and comes into contact with the inner wall of the body vessel.

[0027] Alternatively, the catheter may be configured as a balloon catheter, comprising an inflatable balloon for dilating the body lumen to be treated and a balloon-expandable endoluminal prosthesis which, in these cases, is crimped on the balloon's exterior. [0028] Also combinations of these two solutions are possible. For example, an endoluminal prosthesis may be self-expandable, such that, upon release from a cover sheath, it assumes a pre-expanded conformation. In this conformation, the position of the endoluminal prosthesis may be corrected. Thereafter, the endoluminal prosthesis is balloon-expanded, using a dilation balloon, fastening the endoluminal prosthesis to the inner walls of the body lumen.

[0029] A "body lumen", within the scope of the present invention, may be any lumen comprised inside the human or animal body, for example a lumen of the vasculature, the digestive tract, the respiratory- or genitourinary system. The following description mainly refers to the body lumen being a blood vessel, without, however, restricting the scope of the present invention to blood vessels or other parts of the vasculature.

[0030] Within the scope of the present invention, a "guide wire" is a wire used for catheter placement according to the Seldinger-technique. For this purpose, the guide wire is inserted into a body lumen, for example a blood vessel, prior to advancing a catheter. The catheter is then advanced into the blood vessel, whereby it is guided by the guide wire accommodated in the lumen or the lumina of the catheter.

[0031] Such catheters may be either of the "Over the Wire-" or the "Fast- exchange-"type. Over the Wire catheters comprise an internal lumen, extending over the entire length of the catheter, which lumen is provided for accommodating said guide wire. By contrast, Fast-exchange-catheters comprise only a relatively short guide wire lumen, provided at the distal end of the catheter. While Fast-exchange- catheters are comparably easy to use and require shorter guide wires, Over the Wire catheters are generally regarded to be safer in use. This is due to the fact that the catheter is kept in place over its entire length by the guide wire comprised in its interior lumen. [0032] It is understood that the catheter according to the present invention may be either an Over the Wire- or a Fast-exchange-catheter.

[0033] According to the invention, a "catheter shaft" is an essentially tubelike structure. This catheter shaft may have one or several lumens provided therein, for example for accommodating a guide wire, and may also have external structures, for example nose cones, pushing elements or mating structures for engaging a connector.

[0034] Within the scope of the present invention, "holding elements" are understood to be elements connected to the catheter shaft, which elements are adjusted for releasably engaging an endoluminal prosthesis. For this purpose, the holding elements may, for example, comprise hooks engaging the material of the endoluminal prosthesis. During deployment of the endoluminal prosthesis, such holding elements secure the endoluminal prosthesis to the catheter shaft in axial direction, at the same time preventing rapid radial expansion.

[0035] After or at the final stages of such "controlled" deployment, the holding elements disengage or are disengaged from the prosthesis, thus allowing retraction of the catheter.

[0036] Examples for holding elements and their functionality can be found in US 2007/0203503 Al, US 2007/0255386 Al and WO 2009/038949 Al, mentioned at the outset.

[0037] Further, according to the invention, the expression "upstream", with respect to a blood vessel, describes the direction opposing the blood flow, while the expression "downstream" describes the direction following the blood flow. [0038] The expression "proximal", with respect to a catheter, describes the direction towards an operator handling the catheter, while the expression "distal" describes the direction towards the catheter tip, facing away from the operator.

[0039] For insertion of an endoluminal prosthesis into a blood vessel, the novel catheter may be used following exactly the use of the catheters known in the art. The catheter is inserted, via a guide wire, into a blood vessel. Then, the endoluminal prosthesis is deployed by release from a cover sheath and/or dilation with a dilation balloon provided on the catheter. During these processes, the endoluminal prosthesis preferably remains engaged by the holding elements provided on the catheter. After positioning or final dilation of the endoluminal prosthesis, the endoluminal prosthesis is released from the catheter by disengaging the holding elements from the endoluminal prosthesis. After this, the catheter is retrieved.

[0040] The differences in use between the novel catheter and the catheters known from the art become evident only, when jamming of holding elements to the endoluminal prosthesis occurs. In such a case, the known catheters cannot be retrieved endoluminally from the blood vessel but have to be released from the endoluminal prosthesis in open surgery.

[0041] By contrast, the novel catheter is constructed such that in such a jamming or emergency situation the holding elements are released from the catheter shaft, making the catheter movable with respect to the endoluminal prosthesis.

[0042] Hence, even though jamming of the holding elements at the prosthesis may not under all circumstances be avoided, the novel catheter does not become entrapped within the vasculature of the patient.

[0043] As a result, the catheter shaft can be retracted and the operation can be finished. [0044] Due to the fact, that in this emergency situation some or all of the holding elements remain within the body lumen at least temporarily, the outcome of this operation is an intermediate state. In this state, regeneration of the patient may be allowed for a certain duration of time until a further surgery is done in order to remove the holding elements still present somewhere in the patient. This retrieval of the holding elements may then be achieved either using a retrieval catheter or applying open surgery.

[0045] Due to the additional time allowed for the patient's recovery, the lethality rate of the retrieval operation is markedly decreased.

[0046] Hence, the object underlying the invention is fully achieved.

[0047] In this connection, it is preferred if said holding elements are fixedly connected to a connector that is releasably connected to the catheter shaft.

[0048] A "connector" within the scope of the present invention firmly but releasably engages the catheter shaft, but is tightly, irremovably connected to one or several or, preferably, all of the holding elements. The release mechanism of the connector, and respectively the catheter, is configured such that it requires direct and conscious triggering by the operator.

[0049] When jamming of holding elements to a prosthesis occurs, not all holding elements of the catheter may be affected. Hence, when the holding elements are released individually from the catheter, holding elements without jamming connection to the endoluminal prosthesis are released directly into the patient's vasculature.

[0050] Even jammed holding elements might, after some time, be released into the patient's vasculature due to the movements of the vasculature, in particular triggered by pulsing blood flow from the heart. [0051] Owing to their little cross section, these individual holding elements might be carried deeply into the patient's vasculature from which they might be retrievable only in extensive open surgery. Moreover, such small holding elements might embolize small vessels, potentially resulting in severe tissue and organ damage.

[0052] In this connection, it is of advantage if the holding elements, rather than being individually released from the catheter, remain attached to a larger structure comprised of the connector and the holding elements connected thereto.

[0053] Hence, the holding elements, due to sterical hindrance of the large structure preventing it from entering small vessels, remain inside the large, easily accessible vessels of the patient's vasculature, from where they ideally can be removed later with a retrieval catheter or by open surgery.

[0054] In this connection, it is preferred if said connector comprises at least two connector elements.

[0055] This has the advantage that release of the connector from the catheter shaft is facilitated.

[0056] Upon release, the at least two connector elements separate from each other and from the catheter shaft. During this process, connector elements, still connected to the endoluminal prosthesis via jammed holding elements, are shifted by relaxation of the elastic tension of the holding elements and by the blood stream present inside the blood vessel to lateral positions within the blood vessel. Connector elements not connected any more to the endoluminal prosthesis are carried by the blood stream to a more downstream position in the vasculature.

[0057] Hence, the central lumen of the blood vessel is not obstructed by the connector elements and the holding elements, and the catheter can be safely retracted. [0058] Moreover, it is preferred if said connector elements each comprise a recess engaging a mating structure on said catheter shaft.

[0059] This mating structure may have the overall shape of a rotation body, like a sphere or cylinder, or may, for example, have a shape similar to the threaded core member described in US 2007/025586 Al, mentioned at the outset.

[0060] The recesses in the connector elements then usually have a mating opposite shape, tightly engaging the structure on the catheter shaft.

[0061] Hence, the engagement of the mating structure and the connector elements provides for longitudinal fixation of the connector with respect to the catheter shaft.

[0062] Further, the mating structure and the connector elements may engage each other also against movement in rotational direction.

[0063] In this case, the connector is fixed to the catheter shaft with respect to any degree of freedom.

[0064] The advantage here is that the connector is fixed such that the holding elements, being attached to the connector, can exert force on the endoluminal prosthesis to be deployed inside the blood vessel such that the endoluminal prosthesis, during positioning, may be shifted with respect to its longitudinal position, and may be rotated as well.

[0065] This facilitates correct positioning of the endoluminal prosthesis.

[0066] Further, it is preferred if said connector elements are connected to each other by a connection wire. [0067] This connection wire may be either relatively stiff or flexible or may be comprised of a shape memory material such as Nitinol. Hence, when during an emergency release the connector elements are released from the catheter shaft, connector elements, which are connected to not jammed holding elements and, hence, are free to follow the blood stream, will not be carried away within the blood stream to downstream positions where they might partly obstruct tighter blood vessels.

[0068] Rather, also such connector elements together with "their" attached non jammed holding elements will stay, connected to the jammed holding elements and, hence, remain close to that part of the blood vessel, in which the endoluminal prosthesis has been deployed.

[0069] Hence, downstream embolization by connector elements is prevented.

[0070] It is further preferred if said connector elements are permeable to the flow of blood.

[0071] As with the flexible connection between connector elements, the advantage in this case is that downstream embolization of blood vessels by connector elements released from the endoluminal prosthesis after the release from the catheter is efficiently prevented. Even substantial reduction of blood flow, caused by connector elements being stuck inside a major blood vessel, can, at large, be avoided.

[0072] As, in this connection, the connector elements generally comprise a larger surface than solid connector elements, it is especially advantageous if such connector elements are, in addition, coated with an anti-thrombogenic coating. [0073] Hence, the duration between endol uminal prosthesis deployment and an additional intervention for retrieving the connector elements may be prolonged while reducing the embolic risk.

[0074] It is also preferred if said connector is, in normal operation of said catheter, secured to said catheter by a cover sheath.

[0075] Such cover sheaths are widely used in catheters for endoluminal prosthesis deployment for constraining within their interior self-expandable prostheses and for protecting the vasculature from protruding parts of catheters and/or endoluminal prostheses during catheter insertion.

[0076] When the novel catheter comprises a cover sheath, the cover sheath in this connection may fulfill a triple function. It may, in an initial position, protect the vasculature from the catheter's interior structures while constraining the endoluminal prosthesis. When retracted into a release position, for example proximal to said initial position, it releases the endoluminal prosthesis, allowing the deployment of the endoluminal prosthesis. In this release position, the cover sheath still encloses the connector, fastening it to the catheter shaft.

[0077] Further, the holding elements are still connected to the endoluminal prosthesis after at least partial release of said prosthesis from the cover sheath. Hence, the position of the endoluminal prosthesis may be corrected via the holding elements. If the holding elements of the catheter become jammed to the endoluminal prosthesis, the cover sheath is retracted to an emergency position proximal to said release position, whereupon the connector is released and the catheter can be retracted from the blood vessel.

[0078] The advantage here is that securing and releasing of the connector is achieved in a mechanically very simple manner, necessitating no additional movable parts within or about the deployment catheter. [0079] Rather, only parts already necessary for the normal operation of the novel catheter are required.

[0080] Alternatively or in addition, according to a further embodiment of the present invention, said connector is, in normal operation of said catheter, secured to said catheter by one or more wires.

[0081] In this connection, the wires traverse channels formed within the connector and the shaft especially in the region of the mating element. These channels and the wires accommodated therein are configured such that tight positive lockings are formed by the wires between the connector on one side and the mating structure and shaft on the other side.

[0082] For this purpose, the channels have a diameter which is only slightly larger than the diameter of the wires, allowing the wires to slide within the channels while at the same time maintaining tight lateral guidance of the wires.

[0083] Depending on the shape of the connector elements, the mating element and the shaft, there do exist one or more transition points between the parts of the channels comprised within the catheter shaft and the mating element and the parts of the channels comprised in the connector. Wires traversing such transition point engage with both respective channel parts, thereby forming a positive locking between such channel parts.

[0084] Accordingly, in normal operation of the catheter, the wires hold shaft and connector together.

[0085] For releasing the connector elements from the catheter shaft, the wires are retracted from the channels into an emergency position. This emergency position is chosen such that the distal ends of the wires are located proximal of the transition points mentioned hereinabove. Hence, the positive lockings are dissipated and the connector can freely part from the catheter shaft.

[0086] In this connection, in case the connector is comprised of two or more connector elements, at least a single wire may be provided for each connector element.

[0087] Moreover, the catheter may be configured such that the wires securing any connector element are retractable independently from the wires securing other connector elements. Thus connector elements can individually be released from the catheter.

[0088] The advantage in this case is that the operator has the possibility to release only those connector elements, which are attached to jammed holding elements, while leaving the others secured to the catheter.

[0089] Accordingly, the amount of catheter material remaining within the patient is minimized, reducing the danger of downstream embolization as well as the danger of thrombus formation, elicited by the surfaces of the connector elements and holding elements left behind.

[0090] It is further preferred if said one or more wires are as well used for actuating said holding elements.

[0091] For example, when using holding elements comprising hooks of the kind described in US 2007/0203503 Al, the wires, in their initial positions, engage with cuts in the apexes of the hooks, locking the hooks in a 180° loop conformation firmly engaging with the material of the endoluminal prosthesis.

[0092] For release of the endoluminal prosthesis, the wires are retracted in proximal direction into a release position. The wires hence release the hook's apex, allowing it to stretch and to release the material of the endoluminai prosthesis. At this stage, the wires still hold connector and catheter shaft together.

[0093] Once a holding element becomes jammed to the endoluminai prosthesis, the wires are retracted to an emergency position, their distal ends then being located proximal to the channels connecting connector and catheter shaft. In this configuration, the connector is released from the catheter shaft.

[0094] In a catheter employing holding means of the kind described hereinabove, the means for securing and releasing said connector correspond to parts already required for the catheter's normal operation. Hence, like described before in connection with the cover sheath, no additional movable parts have to be included into such catheter.

[0095] When combining the two safety release mechanisms mentioned hereinabove in one catheter, the advantage is that unwanted release of the connector elements can be even better prevented.

[0096] This is the case, because the release of the connector elements requires two independent, subsequent release operations to be performed by the operator. Still, in this case, there exists no need for additional movable parts to be incorporated into the catheter shaft.

[0097] Further, it is preferred if the catheter comprises one or more release handles for releasing said connector from said catheter shaft, whereby said one or more release handles preferably are connected to said cover sheath and/or said wires.

[0098] For example, a release handle may be configured such that it is dis- tally connected to a cover sheath and/or wires for actuating the holding elements and for deploying the endoluminai prosthesis. Accordingly, the release handle has a distal initial position, in which the endoluminai prosthesis is secured to the catheter by a cover sheath and/or holdi ng elements. When the endoluminal prosthesis is to be released, the release handle is retracted in proximal direction into a release position, retracting the cover sheath and/or the wires such that the endoluminal prosthesis is released from the catheter.

[0099] In case holding elements become jammed to the endoluminal prosthesis, the release handle is retracted further in proximal direction into an emergency position. When the release handle is in emergency position, the cover sheath and/or the wires no longer secure the connector to the catheter, the connector is released from the catheter shaft and the catheter can be retracted from the blood vessel.

[0100] It is, in this connection, especially preferred if the one or more release handles, in normal operation of said catheter, are blocked by one or more safety elements from releasing said connector from said catheter shaft.

[0101] In the scope of the present invention, a "safety element" is understood to by any kind of structure that can block the moving of the release handle, for example in proximal direction. Such safety element is usually configured such that it can only be removed deliberately.

[0102] In order to avoid unwanted retraction of the release handle into its emergency position during normal operation, the safety element blocks the retraction of the release handle from its release position into its more proximal emergency position.

[0103] This is advantageous, because in normal operation of the catheter, the holding elements, preferably, are adjusted to exert force on the endoluminal prosthesis to be deployed in several degrees of freedom, in particular in longitudinal direction as well as in rotational direction. [0104] An unwanted release of connector elements and, respectively, holding elements would result in a situation comparable to the situation found with catheters not having holding elements at all. Rapid radial expansion and, therefore, misplacement of the endoluminal prosthesis might occur in this case.

[0105] According to a different embodiment, several release handles are provided, allowing retracting cover sheath and wires independently or even allowing retraction of certain wires independent of other wires. Hence, individual release of connector elements from the catheter can be achieved.

[0106] In this connection, each release handle may be blocked individually by a safety element.

[0107] Generally, it is preferred if the connector and/or the holding elements comprise radiopaque markers.

[0108] The advantage here is that connector and holding elements remaining within the patient's body due to emergency retrieval of the catheter can be localized at a later stage within the patient via X-ray.

[0109] It is understood that the features described hereinabove and those still to be described below fall within the scope of the present invention not only in the respectively specified combinations, but also in different combinations or on their own.

[0110] Further features follow from the description and the preferred embodiments.

[0111] Preferred embodiments are shown in the Figures and are described in further detail hereinbelow. [0112] In the Figures:

Fig. 1 shows, in longitudinal section, a catheter according to a first embodiment of the invention, comprising a cover sheath located in its initial position;

Fig. 2 shows the catheter of Fig. 1, but with the cover sheath having assumed its release position;

Fig. 3 shows the catheter of Fig. 2, but with the cover sheath having assumed its emergency position;

Fig. 4 shows the blood vessel as in Fig. 3, but with the catheter having been retracted from the blood vessel;

Fig. 5 shows a part of the catheter according to an alternative embodiment of the invention, with wires located in their initial positions;

Fig. 6 shows the part of Fig. 5, but with the wires having assumed their release positions;

Fig. 7 shows the part of Fig. 6, but with the wires having assumed their emergency positions; and

Fig. 8 shows in side view an embodiment of a catheter handle.

[0113] When treating a blood vessel with an endoluminal prosthesis, as a first step, a catheter 10 is inserted into the blood vessel to be treated with the endoluminal prosthesis. In the present embodiment, the blood vessel to be treated is an aorta 11. [0114] Fig. 1 shows catheter 10 being inserted into aorta 11. Aorta 11 comprises an aortic valve 12. Catheter 10 comprises a catheter shaft 13 with a central lumen 14 for accommodating a guide wire 15. Said guide wire 15 has been inserted into aorta 11 and through aortic valve 12 prior to catheter advancement and, during advancement of catheter 10, has served to guide catheter 10 through aorta 11 and aortic valve 12. A nose cone 16, being provided at the distal end of the catheter shaft 13, serves to protect the vasculature from damage during catheter advancement.

[0115] Further, a cover sheath 17 is provided on catheter 10, which cover sheath 17 engages, in its initial position, a circumferential recess 18 on said nose cone 16. Cover sheath 17 can be shifted along the longitudinal axis of the catheter by means of actuating elements 19. Cover sheath 17 serves to protect aorta 11 from damages inflicted by interior structures of catheter 10 and additionally keeps radially compressed in its interior an endoluminal aortic valve prosthesis 21.

[0116] Endoluminal aortic valve prosthesis 21 is provided in between catheter shaft 13 and cover sheath 17 and, in the present example, is self-expandable.

[0117] Endoluminal aortic valve prosthesis 21, during the deployment process, is held in position with respect to catheter shaft 13 by a multitude of holding elements 22 proximally engaging said endoluminal aortic valve prosthesis 21 and being connected to said catheter shaft 13 via a connector 23.

[0118] The holding elements 22 are configured as hooks that engage struts of the endoluminal prosthesis. Such holding elements 22 are described, for example, in US 2007/0203503 Al, mentioned at the outset.

[0119] These holding elements 22 serve the positioning of endoluminal prosthesis 21 after its deployment from cover sheath 17. Additionally, they prevent rapid radial expansion of endoluminal prosthesis 21. Moreover, holding elements 22 may be used to hold endoluminal prosthesis 21 in place while cover sheath 17 is re- advanced, hence enabling the re-constraining and retraction of endoluminal prosthesis 21 from aorta 11.

[0120] Connector 23 is comprised of two connector elements 24. These connector elements each comprise a recess 25 engaging a mating structure 26 fixedly provided on catheter shaft 13. In the present embodiment, mating structure 26 has a ball-like shape. Hence, connector 23 is secured to catheter shaft 13 in axial direction as long as it is covered by cover sheath 7.

[0121] Connector elements 24 are comprised of a porous material or comprise holes, allowing the passage of blood through the connector elements 24.

[0122] In a second step of treating aorta 11 with said self-expandable endoluminal aortic valve prosthesis 21, cover sheath 17 is shifted in proximal direction from its initial position towards its release position.

[0123] This situation is shown in Fig. 2, which shows the catheter 10 as in Fig. 1 but with endoluminal prosthesis 21 being partially deployed.

[0124] Cover sheath 17 has been shifted with respect to the longitudinal axis of catheter 10 in proximal direction, now having assumed its release position that is proximal to endoluminal prosthesis 21 and holding elements 22, but still overlaps connector 23 and, accordingly, mating structure 26.

[0125] Thus, connector 23 is still safely fixed to catheter shaft 13.

[0126] Endoluminal prosthesis 21 has self-expanded almost over its entire length. On its proximal end, endoluminal prosthesis 21 is still engaged by holding elements 22. [0127] In normal operation of the catheter 10, holding elements 22 are now released from endoluminal prosthesis 21, allowing it to gently expand into its final conformation, firmly engaging the walls of aorta 1 1. After disengagement of holding elements 22 from endoluminal prosthesis 21, cover sheath 17 is shifted in distal direction covering holding elements 22 and, finally, engaging circumferential recess 18 on nose cone 16. After this, catheter 10 can be safely retracted from aorta 11.

[0128] It is during release of holding elements 22 from endoluminal prosthesis 21 that jamming of holding elements 22 may occur. As a consequence, holding elements 22 cannot be released from endoluminal prosthesis 21 and catheter 10 cannot be retracted from aorta 11.

[0129] At this point, the novel catheter 10 provides means for releasing holding elements 22 from catheter shaft 13. These means, primarily, are comprised of releasable connector 23.

[0130] Fig. 3 shows the catheter as in Fig. 2, but with connector elements 24 having been released from the catheter shaft 13.

[0131] Cover sheath 17 has been retracted into an emergency position, said emergency position being proximal to the position of said connector elements 24 and mating structure 26. Hence, connector elements 24 are no longer fixed to catheter shaft 13 and are released into the lumen of aorta 11.

[0132] After their release from catheter shaft 13, connector elements 24 still remain connected to each other by a connecting wire 27. Owing to this interconnection of connector elements 24, both connector elements 24 remain close to the position of endoluminal prosthesis 21. Hence, at least as long as one or more of the holding elements 22 remain jammed to endoluminal prosthesis 21, connector elements 24 and holding elements 22 connected thereto are prevented from being carried by the blood stream into the downstream vasculature. [0133] Further, catheter shaft 13 is no longer connected to endoluminal prosthesis 21 and catheter 10 can safely be retracted from aorta 11.

[0134] Fig. 4 shows aorta 11 as in Figs. 1 to 3, but with catheter 10 having been retracted.

[0135] One of connector elements 24 is still connected to endoluminal prosthesis 21 via a jammed holding element 22. The other connector element 24, including the holding elements 22 attached thereto, is released from endoluminal prosthesis 21 and has entered the lumen of aorta 11. Said released connector element 24 is held close to the position of endoluminal prosthesis 21 by being connected to jammed holding element 24 via connection wire 27.

[0136] When, during or after the retraction of catheter 10 from aorta 11, also the jammed holding element 22 is released from endoluminal prosthesis 21, for example due to natural vascular movements, both connector elements are jointly transported by the blood stream into the downstream vasculature. In this situation, the blood permeability of the connector elements 24, resulting e.g. from pores or holes comprised in the material of the connector elements 24 and not detectable from the drawings, prevents the occlusion of downstream vessels by the connector elements 24. In such an event, the connection wire 27 between connector elements 24 has the effect that both connector elements 24 later can be jointly retrieved from the patient's vasculature.

[0137] Radiopaque markers 28 are provided on connector elements 24, holding elements 22 and connection wire 27.

[0138] Hence, prior to removal of connector elements 24, holding elements 22 and connection wire 27 by open surgery, the exact location and potentially even respective orientation of these structures can be visualized using X-Ray. [0139] This way, retrieval of connector elements 24, holding elements 22 and connecting wire 27 from a patient's vasculature is markedly simplified. This holds true especially in cases where these structures have been released from endo- luminal prosthesis 21 and carried downstream to a different location within the patient's vasculature.

[0140] Fig. 5 shows, in an enlarged sectional side view, a part of a catheter 29 according to an alternative embodiment of the present invention.

[0141] Catheter 29 comprises holding elements 31, irremovably connected to a connector 30 which is comprised of connector elements 32. Connector elements 32, with their recesses 33, engage mating structure 34 on catheter shaft 35. Holding elements 31, at their distal ends, comprise hooks 36 engaging endoluminal prosthesis 21.

[0142] In this embodiment, connector elements 32 are not secured to catheter shaft 35 via a constraining sheath 17, as in the embodiment of Figs. 1 to 3, but rather are held in position by wires 37.

[0143] Said wires 37 are guided through catheter shaft 35 and connector elements 32 in such way that they structurally tether connector elements 32 to catheter shaft 35 by means of a positive locking. This is achieved by accommodating wires 37 in channels 38 that traverse connector elements 32, mating structure 34 and catheter shaft 35.

[0144] Moreover, in their initial position, wires 37 keep closed hooks 36 provided on holding elements 31 in a manner known for example from US 2007/0203503 Al .

[0145] In order to release hooks 36 from endoluminal prosthesis 21, wires 37 are retracted by the operator through channels 38 into their release position. [0146] The result of this process is shown in Fig. 6, which shows the part of catheter 29 as in Fig. 5, but with wires 37 having assumed their release positions.

[0147] In normal operation, wires 37 are retracted into their proximal release position, with their distal ends being located proximal to hooks 36, allowing hooks 36 to open up and release endol uminal prosthesis 21. Thereby, wires 37 still firmly secure connector elements 32 to catheter shaft 35.

[0148] During deployment of endoluminal prosthesis 21, incomplete opening of one or more hooks 36 may occur, entailing the jamming of hooks 36 to endoluminal prosthesis 21. In such case, catheter 29 is still tightly connected to endoluminal prosthesis 21 even after completion of the deployment-process.

[0149] Hence, in order to be able to retract catheter 29 from the patient's vasculature, the operator has to trigger the release of connector 30, connected to jammed holding element 31.

[0150] The result of this process is shown in Fig. 7, which shows the part of catheter 29 as in Figs. 5 and 6, but with wires 37 having assumed their emergency positions proximal to their release positions.

[0151] In order to release connector elements 32, the operator retracts wires 37 through channels 38 into their emergency position, with their distal ends being located proximal connector elements 32.

[0152] Hence, the positive locking formed by wires 37 between connector elements 32 on one side and mating structure 34 and shaft 35 on the other side are dissipated. Accordingly, connector elements 32 no longer are secured to catheter shaft 35 and are released from catheter 29. [0153] Subsequently, catheter 29 can be retracted from the patient's vasculature, resulting in the situation shown in Fig. 4

[0154] Fig. 8 shows a proximal part of a catheter 10/29 according to an embodiment of the present invention, catheter 10/29 having a catheter handle 39. Catheter handle 39 is connected to catheter shaft 13/35. A release handle 41 is slidably provided on catheter shaft 13/35. Release handle 41 may be connected to actuating element 19 of the embodiment shown in Fig. 1, and thus to cover sheath 17. Alternatively or in addition, release handle 41 may be connected to one or several wires 37 of the embodiment shown in Figs. 5 to 7.

[0155] A breakable handle 42 is provided on catheter shaft 13/35.

[0156] During normal operation of catheter 10/29, breakable handle 42 prevents the retraction of release handle 41 beyond the release position shown in Fig. 8.

[0157] When, during release of endoluminal prosthesis 21, catheter 10/29 becomes jammed inside the blood vessel, breakable handle 42 is removed from catheter shaft 13/35.

[0158] Then, release handle 41 can be shifted into a more proximal emergency position releasing connector elements 24 from catheter shaft 13/35.

[0159] In such emergency situation, connector elements 24, holding elements 22 and connecting wire 27 remain within the patient after catheter shaft 13/35 has been retracted, and have to be removed from the patient later.

[0160] To summarize, the new catheter enables the save deployment of endoluminal prostheses of large diameters. [0161] Such catheter, despite the jamming of one or more of the holding elements, may be released endoluminally.

[0162] Thus, the novel catheter makes unnecessary immediate open surgical removal of a jammed catheter when jamming of holding elements occurs in the course of endoluminal treatment of a body lumen.

[0163] Hence, the lethality rate during transluminal treatment is lowered.

Claims

Catheter for deploying an endoluminal prosthesis (21) inside a body lumen (11), the catheter comprising a catheter shaft (13, 35) having arranged thereon said endoluminal prosthesis (21), and holding elements (22, 31) for securing, during deployment, said endoluminal prosthesis (21) to said catheter shaft (13, 35), which holding elements (22, 31) are releasably connected to the endoluminal prosthesis (21) and are connected to the catheter shaft (13, 35), characterized in that said holding elements (22, 31) are releasably connected to said catheter shaft (13, 35).

Catheter according to claim 1, characterized in that said holding elements (22, 31) are fixedly connected to a connector (23, 30) that is releasably connected to the catheter shaft (13, 35).

Catheter according to claim 1 or claim 2, characterized in that said connector (23, 30) comprises at least two connector elements (24, 32).

Catheter according to claim 3, characterized in that said connector elements (24, 32) each comprise a recess (25, 33) engaging a mating structure (26, 34) on said catheter shaft (13, 35).

5. Catheter according to claim 4, characterized in that said connector elements (24, 32) are connected to each other by a connection wire (27).

6. Catheter according to anyone of claims 3 to 5, characterized in that said connector elements (24, 32) are permeable to the flow of blood.

7. Catheter according to anyone of claims 2 to 6, characterized in that said connector (23, 30) is, in normal operation of said catheter (10, 29), secured to said catheter (10, 29) by a cover sheath (17).

8. Catheter according to anyone of claims 1 to 7, characterized in that said connector (23, 30) is, in normal operation of said catheter (10, 29), secured to said catheter (10, 29) by one or more wires (37).

9. Catheter according to claim 8, characterized in that said one or more wires (37) are as well used for actuating said holding elements (22, 31).

10. Catheter according to anyone of claims 2 to 9, characterized in that it comprises one or more release handles (41) for releasing said connector (23, 30) from said catheter shaft (13, 35).

11. Catheter according to claim 10, characterized in that the one or more release handles (41) are connected to said cover sheath (17).

12. Catheter according to claim 10 or 11, characterized in that the one or more release handles (41) are connected to said wires (37).

13. Catheter according to anyone of claims 10 to 12, characterized in that the one or more release handles (41), in normal operation of said catheter (10, 29), are blocked by one or more safety elements (42) from releasing said connector (23, 30) from said catheter shaft (13, 35).

14. Catheter according to anyone of claims 2 to 13, characterized in that the connector (23, 30) and/or the holding elements (22, 31) comprise radiopaque markers (32).