Removable support device

[0002] This application is a continuation-in-part application of U.S. patent application Ser. No. 09/199,556 filed Nov. 25, 1998.

[0003] This application is a continuation-in-part of a co-pending application entitled “CATHETER”, filed Nov. 25, 1998.

[0004] The present invention relates to a method and a device for widening tubular organs in general and to a method and a device for widening arteries in particular.

[0005] Devices and methods for widening tube shaped organs, in general and in the human body, in particular, are known in the art.

[0006] U.S. Pat. No. 5,716,410, to Wang et al, is directed to a catheter for vascular use. The catheter includes a directing mechanism and an inflatable balloon at the tip. The tip also includes a temporary stent, made of thermoplastic material. The catheter is inserted into the body of the patient, via a wide surface artery and the operator directs the catheter toward the destination location. When the tip is positioned at the destination location, then the operator pumps fluid to the balloon, via a tube, running along the catheter and starts inflating the balloon.

[0007] Reference is now made to FIG. 2, provided by Wang et al as FIG. 1, which is an illustration of a catheter, known in the art.

[0008] At the same time, the thermoplastic stent is heated, thereby unlocking its shape. The balloon, as it inflates, applies circumferencial pressure on the stent and the tubular organ, thereby forcing them to extend. Accordingly, the circumference of the tubular organ becomes larger. When the balloon brings the thermoplastic stent to the destination diameter, then the thermoplastic stent is cooled, thereby fixing its shape at a larger diameter, where it supports the tubular organ at an enlarged position.

[0009] Then, the operator, reduces the pressure within the balloon, which in turn deflates and becomes smaller than the enlarged circumference of the tubular organ. The thermoplastic stent is then kept within the tubular organ for a time period which may range from a few minutes to as long as a week. Finally, the thermoplastic stent is reheated, thereby unlocking its shape, and enabling its removal from the body of the patient.

[0010] It will be appreciated by those skilled in the art, that a balloon is often longer than the segment to be treated. Hence, the inflatable portion of the balloon extends beyond the desired segments to healthy segments, and can cause damage thereto.

[0011] Furthermore, when a balloon is inflated inside a blood vessel, it occludes the blood flow distally and becomes a full barrier for any blood flow therein. It will be appreciated by those skilled in the art that many blood vessel related balloon treatments are performed in coronary arteries. Accordingly, such a procedure, while blocking blood flow through the treated blood vessel, may cause ischemia or even cardiac arrest.

[0012] The balloon blocks the blood flow both in the axial (through the blood vessel) and radial directions blocking branches.

[0013] The complete obstruction, a balloon related treatment is usually limited to one or two minutes of inflation, since the patient can not tolerate long time inflations, because of severe pain and chest discomfort, due to ischemia.

[0014] It will be appreciated by those skilled in the art that a blood vessel is generally a flexible organ. This fact, combined with the short time period in which a balloon expands the circumference of the blood vessel, (as much as 40% of the cases) causes the balloon treated blood vessel to assume its original size (recoil) immediately, or within few months shortly after the treatment.

[0015] A stent is generally an element which is inserted into the tubular organ with the aid of a catheter. The initial shape of a stent is of an elongated cylinder, having a diameter which is smaller than the narrowed section of the tubular organ, through which it has to pass. At the beginning of the treatment, the stent is positioned in the stenosed segment.

[0016] Then, the circumference of the stent is widened, by various methods, known in the art. One of these methods includes inserting a balloon into the stent and applying pressure by inflating it therewith. Accordingly, the stent widens, thereby applying pressure on the narrowed blood vessel. As a result, the stent widens the cross section of the diseased segment.

[0017] Finally, the balloon is deflated and is removed from the stent, which remains in its widened position, forcing the widened blood vessel to remain at its new state. Afterwards, the stent is covered by local tissue and is anchored thereto. This poses a disadvantage in the usage of a stent since such a stent can not be removed. A stent is an alien element within a living organism, which might produce thrombus in it.

[0018] In many cases (15%-40%) instent stenosis occurs. The mechanism of this narrowing is intimal proliferation thereby causing a new blockage at the same location. It is known by those skilled in the art that sometimes, such a reoccurring blockage is difficult to treat and in some cases, surgery is needed, to remove and replace the clogged section.

[0019] In some instances the stent may be lost and migrate distally in the coronary artery, or sometimes in the aorta and its branches. The stent also can be stucked.

[0020] Shape memory effect (SME) is a phenomena, in shape memory alloys (SMA) of a reversible transition from one solid phase into the other (i.e., from Martensite into Austenite or from Austenite to Martensite). Heating the alloy causes the transition from Martensite into Austenite. Cooling the alloy causes the reverse transition, from Austenite into Martensite. NiTi alloys are examples for such shape memory alloys.

[0021] Martensite and Austenite are two solid state phases, which are typical for alloys. Each of these phases is characterized in a certain crystaline structure.

[0022] Basically there are two types of shape memory effects. The first type is called the one way shape memory effect (OWSM), where the material transits from one of the above phase states to the other, only once. The second type is called the two way shape memory effect (TWSM), where the material transits from one of the phase states to the other and back in a reversible process.

[0023] Shape memory alloys, such as Ni—Ti, Ni—Ti—X, Cu—Ni—Al, Cu—Zn—Al, Fe—Mn—Si, Ni—Ti—Co, Ni—Cu—X, Ni—Al and the like, are known in the art. These alloys exhibit a shape memory effect. In the martensite condition, the shape alloy material is relatively flexible and soft, and can be easily deformed. When the material undergoes the transition into an austenite state, it becomes more rigid, and is able to apply force and generate work, deform and enlarge the cross section of the blood vessel.

[0024] U.S. Pat. No. 5,540,713 to Shnepp-Pesch et al, is directed to an apparatus for widening a stenosis in a body cavity, also known as a shape memory stent. Shnepp-Pesch describes a stent made from a shape memory alloy, assuming a first predetermined shape at a first predetermined temperature and second predetermined shape at a second predetermined temperature. When heated from the first temperature to the second one, the shape memory stent changes its shape from a narrow generally cylindrical shape to a wider generally cylindrical shape.

[0025] Shnepp-Pesch describe a plurality of shapes which are applicable as shape memory stents. Reference is now made to FIGS. 1A-1H, provided by Shnepp-Pesch et al, as FIGS. 1A, 1B, 2A, 2B, 3A, 3B, 4A and 4B, respectively. These figures describe four shape memory stent structures, each at two states, one narrowed and the other enlarged.

[0026] It will be appreciated by those skilled in the art that this stent basically suffers the same disadvantages as any other stent, known in the art, as listed above.

[0027] It is an object of the present invention to provide a system for opening and temporarily supporting generally tubular organs, in general and arteries in particular.

[0028] It is a further object of the present invention to provide a novel method for temporarily supporting a tubular organ, in general and vascular organs in particular.

[0029] In accordance with the present invention, there is thus provided a system for opening and temporarily supporting a section of a generally tubular organ. The system includes a dilation catheter and an inflatable balloon. The dilation catheter includes an integrally connected shape memory catheter tip. The shape memory catheter tip is made of a shape memory alloy. The balloon is inserted within the shape memory catheter tip. The balloon is operative to inflate, thereby moving the shape memory catheter tip from a first shape into a second shape. The shape memory catheter tip changes from the second shape to the first shape when heated from a first temperature to a second temperature.

[0030] According to one aspect of the invention, the shape memory catheter tip is generally hollow, thereby enabling flow of bodily fluid therethrough.

[0031] The system can further include an energy control unit, which is connected to the dilation catheter, for controlling the temperature of the shape memory catheter tip, and an energy transfer unit, connected between the shape memory catheter tip and the energy control unit, and generally located within the dilating catheter, for transferring energy therebetween.

[0032] According to another aspect of the invention, the shape memory catheter tip includes a generally cylindrical coil. This generally cylindrical coil can have a solid cross section, or a hollow one. The generally cylindrical coil can have a cross section, which is selected from the list consisting of a radial cross section, a elliptical cross section, a semi radial cross section, a semi elliptical cross section, a near rectangular cross section, and the like.

[0033] According to a further aspect of the invention, the first shape is generally the shape of a cylindrical coil having a first diameter and wherein the second shape is generally the shape of a cylindrical coil having a second diameter.

[0034] According to one aspect of the invention, the energy transfer means includes at least one conduit, and the temperature control unit includes means for providing temperature-controlled fluid towards the shape memory unit via the energy transfer means. One of the conduits, can be opened in the vicinity of the shape memory catheter tip, thereby releasing temperature controlled fluid in the vicinity of the shape memory catheter tip.

[0035] The shape memory catheter tip can include a generally cylindrical coil, having a hollow cross section. Accordingly, the generally cylindrical coil is connected to the at least one conduit at a first end, the generally cylindrical coil being open at a second end. One of these conduits, transfers temperature controlled fluid to the shape memory catheter tip, via the first end. The shape memory catheter tip releasing the temperature controlled fluid via the second end.

[0036] The temperature control unit can be further connected electrically to the shape memory unit, thereby electrically heating the shape memory unit from the first temperature to the second temperature.

[0037] The energy transfer means can include an electricity-conducting unit, connected electrically to the shape memory unit. The temperature control unit includes an electric power supply unit, for electrically heating the shape memory unit from the first temperature to the second temperature.

[0038] According to an aspect of the invention, the first temperature can be equal or below the temperature of the environment, in which the shape memory catheter tip is placed.

[0039] The shape memory alloy can be selected from the list consisting of Ni—Ti, Ni—Ti—X, Cu—Ni—Al, Cu—Zn—Al, Fe—Mn—Si, Ni—Ti—Co, Ni—Cu—X, Ni—Al, and the like.

[0040] The first temperature can be in the range of 5 degrees Celsius and 38 degrees Celsius. Alternatively, the first temperature can be in the range of 20 degrees Celsius and 38 degrees Celsius. The second temperature can be in the range of 36 degrees Celsius and 65 degrees Celsius. Alternatively, the second temperature is in the range of 36 degrees Celsius and 46 degrees Celsius.

[0041] According to a further aspect of the invention, the shape memory unit can include a generally cylindrical hollow coil, having an inlet and an outlet. In this case, the temperature transfer means includes two conduits. One of the conduits is connected to the inlet for introducing the fluid thereto. The other conduit is connected to the outlet, for receiving the fluid therefrom.

[0042] The front section of the shape memory catheter tip can be shaped as a guiding front end. Alternatively, the system can include guiding unit having a guiding tip, wherein the guiding unit is located within the dilation catheter and the guiding tip extends beyond the shape memory catheter tip. The guiding tip can be operable to change relative to the shape memory catheter tip.

[0043] According to one aspect of the invention, the first diameter is smaller than the second diameter. According to another aspect of the invention, the first diameter is larger than the second diameter.

[0044] It is noted that can be designed to enable flow of bodily fluid in a radial direction and in an axial direction.

[0045] In accordance with another aspect of the invention, there is provided a method for operating the system of the invention. The method includes the steps of:

[0046] inflating the balloon, thereby increasing the diameter of the shape memory catheter tip, deflating the balloon, thereby enabling flow of bodily fluids through the shape memory catheter tip, heating the shape memory catheter tip to a predetermined temperature, thereby moving the shape memory catheter tip to an Austenite state which decreases the diameter of the shape memory catheter tip.

[0047] The method can include the step of locating the shape memory catheter tip and the balloon in a selected area within a generally tubular organ. In addition, the method can further include a preliminary step of inserting the shape memory catheter tip and the balloon into the body of the patient. Similarly, the method can further include the step of removing the shape memory catheter tip from the selected area.

[0048] The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the drawings in which:

[0049] FIGS. 1A-1H, are schematic illustrations of a tubular restraining devices, which are known in the art;

[0050] FIG. 2 is a schematic illustration of a catheter having a balloon as its tip, which is known in the art;

[0051] FIG. 3 is a schematic illustration of a device for treating a tubular organ, constructed and operative in accordance with a preferred embodiment of the invention;

[0052] FIGS. 4A and 4B are illustrations of the tip end of the device of FIG. 3, constructed and operative in accordance with another preferred embodiment of the present invention;

[0053] FIGS. 5A, 5B, 5C, 5D and 5E are illustrations of typical cross sectional variations for helical SMA element of FIGS. 4A and 4B;

[0054] FIG. 6 is a schematic illustration of a method for operating the device of FIG. 3, operative in accordance with another preferred embodiment of the present invention;

[0055] FIG. 7 is a schematic illustration of a system, constructed and operative in accordance with a further embodiment of the present invention;

[0056] FIG. 8 is a schematic illustration in detail of the connection section of a helical SMA element and the inner side of the guiding catheter;

[0057] FIG. 9 is a schematic illustration in detail of a catheter tip, constructed and operative in accordance with another preferred embodiment of the present invention;

[0058] FIGS. 10A, 10B, 10C, 10D, 10E, 10F and 10G are illustrations of typical cross sectional variations for the catheter tip of FIG. 9;

[0059] FIG. 11 is a schematic illustration of a catheter tip, constructed and operative in accordance with a further preferred embodiment of the present invention;

[0060] FIG. 12 is a schematic illustration of a catheter tip, constructed and operative in accordance with another preferred embodiment of the present invention;

[0061] FIG. 13 is a schematic illustration of a catheter tip, and energy transfer means, constructed and operative in accordance with a further preferred embodiment of the present invention;

[0062] FIG. 14A is an illustration of a catheter system, constructed and operative in accordance with a further preferred embodiment of the present invention;

[0063] FIGS. 14B, 14C, 14D, 14E and 14F are illustrations of parts of the system of FIG. 14A; and

[0064] FIG. 15 is an illustration of a combined catheter tip and balloon assembly, constructed and operative in accordance with another preferred embodiment of the present invention.

[0065] The present invention overcomes the disadvantages of the prior art by providing a novel device which is a catheter, having a hollow SMA element as its tip.

[0066] Furthermore, the present invention provides a novel method for operating the device of the invention, which overcomes the disadvantages of the prior art.

[0067] Reference is now made to FIG. 3 which is a schematic illustration of a device, generally referenced 100, for treating a tubular organ, constructed and operative in accordance with a preferred embodiment of the invention.

[0068] The device 100 includes a guiding catheter 102, a “Y” connector 110, a hollow SMA tip 104, a guidance unit 108 and a fluid supply and temperature control unit 106.

[0069] The guide wire 108 is inserted through guiding catheter 102 via the “Y” connector 110. The temperature control unit is connected to the Hollow SMA tip which is inserted via the “Y” connector 110 and over the guide wire 108.

[0070] The guiding catheter 102 is an elongated tubular element which guides and locates the tip 104 within the patients tubular organ, which for example, can be a blood vessel, a urether, urethra, bile duct, colon eosophagus, stenosed valve, etc. and the like. The user of the device 100, which is a medically trained person, uses the guidance Wire 108 to insert over it SMA tip into the diseased segment.

[0071] Reference is also made now to FIGS. 4A and 4B, which are illustrations of the tip end of the device 100, of FIG. 3. FIG. 4A shows the tip 104 inserted into a blood vessel 152, having a section 158, which is relatively narrower than the rest of the blood vessel.

[0072] The tip 104 includes a hollow shaped SMA element which is adapted to perform a transition from one shape at a first predetermined temperature range to another shape, at a second predetermined temperature range.

[0073] In the present example, the tip includes a helical SMA element 156. The helical SMA element 156 has a narrow circumference shape at a temperature, which is equal or lower to a first temperature value T₁, as shown in FIG. 4A. The helical SMA element 156 has a wide cross section shape at a temperature, which is equal or higher to a second temperature value T₂, as shown in FIG. 4B.

[0074] The helical SMA element 156 is inserted over the guide wire 108 through guiding catheter 102 (FIG. 3). It is shaped so that its front end 164 (FIG. 4) has a round shape which is designed so that no damage is inflicted onto the blood vessel through which the tip is inserted. At its other end 162, the helical SMA element 156 is connected to hollow tubes, which are able to supply various fluid temperatures thereon (shown in detail in conjunction with FIG. 8).

[0075] The device 100 is used to expand the circumference of the blood vessel 152, at its narrowed cross section 158, using the SMA tip 104.

[0076] Accordingly, the user inserts the SMA element 156 into the blood vessel 152 and positions it in the diseased segment 158. It is noted that all through the insertion phase, the helical SMA element 156 is maintained at a temperature, which is not higher than T₁, thereby assuming its narrowed form.

[0077] When the helical SMA element 156 is located within the diseased section 158, then, the user operates the temperature control unit 106, which heats the helical SMA element 156 to a temperature which is not lower than T₂. As the helical SMA element 156 heats, it undergoes a transition from its narrow shape into its wider shape. Accordingly, the helical SMA element 156 applies circumferencial pressure on the diseased segment 158, thereby forcing it to become wider (FIG. 4B).

[0078] According to the present invention, the user can maintain the helical SMA element 156 at its position, for a considerable period of time, which is in the order of minutes, hours and days, as needed.

[0079] As the shape of the helical SMA element 156 does not block flow. No ischemia is produced and hence, no harm or suffer is inflicted onto the patient, during this time period.

[0080] After reducing the SMA element 156 to its' original size, the physician can direct it to another location, within the artery and use it again. Accordingly, the device of the present invention can be used for a plurality of narrowed artery locations, one after the other, without the need to remove the catheter out of the patients body.

[0081] According to the present invention, the heating up and cooling down of the helical SMA element 156 can be performed in a plurality of ways such as inducing a temperature bearing fluid there through, electric current, radiation, induction heating, and the like.

[0082] According to one aspect of the present invention, the helical SMA element 156 is made of a hollow wire, through which temperature bearing fluid is induced or others.

[0083] As the diseased segment 158 is forced to be in a widened state (FIG. 4B) for a considerable time, by the helical SMA element 156, then the probability of it shrinking back to its narrow state (FIG. 4A) decreases significantly.

[0084] At the end of the treatment, the user, operates the temperature control unit 106, to lower the temperature of the helical SMA element 156, which in turn returns to its initial state as shown in FIG. 4A. Finally, the user takes out the SMA catheter 100 than the guide wire 108 and finally the guiding catheter 102 out of the patients body, or to another vessel which needs to be dilated.

[0085] It will be noted that according to this aspect of the present invention, no element such as a stent, remains in the artery, to maintain its widened state, at the end of the treatment. Hence, at any time after the treatment, any type of catheter can be inserted into the artery, passing distally through section 158, for example, for repeating the treatment of section 158.

[0086] According to the present invention, the helical SMA element 156 is made of a hollow conduit. A fluid flowing there through having a predetermined temperature, applies that temperature thereon. Accordingly, a temperature change can be applied on the element 156.

[0087] The side walls of the catheter are substantially round shaped having a smooth surface, for reducing the probability of inflicting any damage to the inside walls of the treated artery (the intima).

[0088] Reference is now made to FIGS. 5A, 5B, 5C, 5D and 5E, which are illustrations of cross sectional variations for helical SMA element 156, constructed and operative in accordance with the present invention.

[0089] FIG. 5A shows a circular cross section, FIG. 5B shows an elliptical cross section, FIG. 5C shows a half elliptical cross section, FIG. 5D shows a near rectangle cross section and FIG. 5E shows a solid (full) radial cross section.

[0090] Reference is now made to FIG. 6, which is a schematic illustration of a method for operating the device 100 of FIG. 3, operative in accordance with another preferred embodiment of the present invention.

[0091] In step 200, a guiding wire is inserted into the tubular organ within the body of the patient, and is guided into the section to be treated. This tubular organ can be, for example, a blood vessel, a urether, a urethra, bile duct, colon, eosophagus, stenosed valve, and the like. In the case of a blood vessel, the guiding tip can be inserted from a peripheral artery.

[0092] In step 201, the device 100, which is an SMA catheter is inserted into the tubular organ, guided via the guiding wire towards the section to be treated.

[0093] In step 202, the device 100 is guided through the tubular organ towards a selected location, which is a portion of the tubular organ which is narrower than as it should be and need to be widened. In the present example, there is a blockage in this location caused by atherosclerosis.

[0094] In step 204, the user, which is part of the medical staff treating the patient, positions the tip of the SMA catheter in the selected location. The SMA element can be heated by fluid, electric current, radiation, induction heating, and the like.

[0095] In step 206, the SMA tip of the device 100 changes from an initial shape to a transition shape. This can be done by means of a phase transition which can be caused by a temperature change (increase). Being in the transition shape, the SMA tip applies circumferencial pressure on the walls of the selected section, thereby forcing it to increase its circumference (208). The tip is maintained in this position and shape, so as to reduce the probability of the selected section returning to its original circumference shortly after the treatment is ended.

[0096] In step 210, the tip element is changed from the transition shape back into the initial shape. This is done by means of a phase transition which is caused by a temperature change (decrease).

[0097] In step 212, the device 100 is removed from the tubular organ. It will be noted that the device 100, can remain in the body of the patient for a subsequent treatment of another such section.

[0098] It is noted that according to the present invention blood flow is maintained throughout the treatment and the device, according to the invention, does not block blood flow neither in the axial direction, nor in the radial direction. Accordingly, the method of the present invention is applicable for patients which may not endure a blood blocking balloon treatment.

[0099] Since the device of the present invention is completely removed from the body of the patient and leaves no object therein, then, the probability of intimal proliferation in the treated segment, is significantly reduced.

[0100] It is noted that the method of the present invention enables the physician to treat conical shaped segment by using conical SMA tip.

[0101] Reference is now made to FIG. 7, which is a schematic illustration of a system, generally referenced 300, constructed and operative in accordance with a further embodiment of the present invention.

[0102] System 300 includes a catheter assembly 302, a guidance unit 308, a fluid connector 306 and a temperature control system 320.

[0103] The catheter assembly 302 includes a tip 304, a temperature sensor 336 for sensing the temperature of the treated area as well as the temperature of the tip 304 and a quick release interface 310. It is noted that the addition of temperature sensors is an option, provided by the invention. This addition enhances the control and accuracy of the temperature of the fluid and hence, the temperature of the SMA tip 304.

[0104] The guidance unit 308 enables the physician to guide the tip of the catheter 302, towards the target area to be treated.

[0105] The fluid connector 306 enables the physician to supply variable fluid temperature and flow into the catheter 302, and the like.

[0106] The temperature control system 320 provides a continuous supply of fluid according to the specification, received from the user via connector 306.

[0107] The temperature control system 320 includes a pump 338, a hot fluid container 322, a cold fluid container 324, a cooling unit 326, a heating unit 328, control valves 332 and 334 and a sensor 330.

[0108] The cooling unit 326 is connected to the cold fluid container 324. The hot fluid container 322, is connected to the heating unit 328 and to the control valves 332 and 334. The control valve 332 is connected between the pump 338 and both containers 324 and 322.

[0109] The pump 338 is further connected to the fluid connector 306, which is further connected to the control valve 334.

[0110] The cooling unit 326 cools the fluid which is contained in the cold fluid container 324. The heating unit 328 heats the fluid which is contained in the hot fluid container 322. The control valve 332 directs fluids received from the cold fluid container 324 and the hot fluid container 322 and provides the fluid to the pump 338.

[0111] The pump 338 provides a fluid at a controlled pressure to the fluid interface 306. This fluid flows towards the tip 304 thereby applying its temperature, thereon (i.e., when the temperature of the fluid is greater than the temperature of the tip, then the tip will be heated up and when the temperature of the fluid is lower than the temperature of the tip, then the tip will cool down).

[0112] After modifying the temperature of the tip 304, the fluid flows back to the temperature control system 320, via the fluid connector 306, to be stored in the containers. The control valve 334 provides fluid to the containers 322 and 324.

[0113] The fluid sensor 330 monitors the fluid at the output of the pump 338, thereby providing data relating to the temperature and pressure of the fluid. This data is used to control the pump 338 and the heating element 328 and the cooling element 326.

[0114] It is noted that the catheter assembly 302, can also conduct fluid, directly therethrough, and release it in the vicinity of the tip. Accordingly, the tip can be made of a wire which has a solid cross-section.

[0115] Reference is further made to FIG. 8, which is a schematic illustration in detail of the connection section of a helical SMA element 356 and the inner side of the guiding catheter 302 (FIG. 8). The helical SMA element 356 includes an inlet 362A and an outlet 362B, which are connected to a fluid inlet conduit 380A and a fluid outlet conduit 380B. the fluid inlet conduit 380A is connected to the inlet 362A, while the fluid outlet conduit 380B is connected to the outlet 362B. Temperature controlled fluid, provided by system 320, is provided to the helical SMA element 356 via the inlet fluid conduit 380A. After modifying the temperature of the helical SMA element 356, the fluid exits via the outlet fluid conduit 380B. It is noted that a guiding wire 360 is inserted through the guiding catheter 302 to the end of the tip 304.

[0116] According to the present example, the helical SMA element 356 is alternatively connected to two electrically conducting wires 384A and 384B, via electrical contacts 364A and 364B, respectively. These wires provide a flow of electrical current via the metal body of the helical SMA element 356, thereby heating it. According to this example, the heating is performed electrically, while the cooling can be performed either by setting the reduced diameter temperature to the body temperature of the patient or by introducing cooled fluid via conduits 380A and 380B.

[0117] Reference is now made to FIGS. 9, 10A, 10B, 10C, 10D, 10E, 10F and 10G. FIG. 9 is a schematic illustration in detail of a catheter tip, generally referenced 400, constructed and operative in accordance with another preferred embodiment of the present invention. FIGS. 10A, 10B, 10C, 10D, 10E, 10F and 10G are illustrations of cross sectional variations for catheter tip 400, which include auxiliary elastic means.

[0118] Catheter tip 400 includes a helical SMA element 402, and a helical elastic element 404, attached thereto. SMA element 402 is generally similar to elements 104 and 304.

[0119] According to one aspect of the invention, the helical elastic element 404 is inserted within helical SMA element 402, as illustrated in FIGS. 10A, 10B, 10C, 10D and 10E. According to a further aspect of the invention (FIGS. 10F and 10G), the helical elastic element 404 is attached to the outer surface of helical SMA element 402.

[0120] FIG. 10A is a cross sectional illustration of a variation of SMA element 402, which includes a hollow helical SMA element 402A having an elliptic cross section and a helical elastic element 404B having an “I” cross section.

[0121] FIG. 10B is a cross sectional illustration of a variation of SMA element 402, which includes a hollow helical SMA element 402B having a semi-elliptic cross section and a helical elastic element 404B having a radial cross section.

[0122] FIG. 10C is a cross sectional illustration of a variation of SMA element 402, which includes a hollow helical SMA element 402C having a near rectangle cross section and a helical elastic element 404C having a radial cross section.

[0123] FIG. 10D is a cross sectional illustration of a variation of SMA element 402, which includes a hollow helical SMA element 402D having an elliptic cross section and a helical elastic element 404D having a radial cross section.

[0124] FIG. 10E is a cross sectional illustration of a variation of SMA element 402, which includes a hollow helical SMA element 402E having a radial cross section and a helical elastic element 404E having an “I” shaped cross section.

[0125] FIG. 10F is a cross sectional illustration of a variation of SMA element 402, which includes a hollow helical SMA element 402F having a radial cross section and an external elastic element 404F.

[0126] FIG. 10G is a cross sectional illustration of a variation of SMA element 402, which includes a solid (full) helical SMA element 402G having a radial cross section and an external elastic element 404G.

[0127] The helical SMA element 402 has a narrow circumference shape at a temperature which is equal to or lower than a first temperature value T₁. The helical SMA element 402 has a wide circumference shape at a temperature which is equal to or higher than a second temperature value T₂.

[0128] The helical elastic element 404 has a narrow diameter shape, which is in the order of the narrow diameter shape of the helical SMA element 402.

[0129] It is noted that the helical elastic element 404 can be deformed to a different shape, by an external force and return back by itself, to its original narrow circumference shape.

[0130] According to the present invention, the catheter tip 400 performs a transition from the narrow circumference shape to a wide circumference shape, by heating the helical SMA element 402 beyond predetermined temperature T₂. At this stage, the helical SMA element 402 is in an Austenite state, where it applies force on helical elastic element 404, thereby deforming it into a shape which is generally the same shape of the helical SMA element 402 (i.e., a wide circumference).

[0131] At a later time, the catheter tip 400 performs a transition from the wide circumference shape, back to the narrow circumference shape, by cooling the helical SMA element 402 below predetermined temperature T₁.

[0132] Accordingly, the helical SMA element 402 transforms into a Martensite state, where it becomes less rigid. Being in the Martensite state, the helical SMA element 402 is no longer able to apply sufficient force onto helical elastic element 404. Hence, the helical elastic element 404, retracting to its initial shape, deforms the helical SMA element 402, into a shape which is generally the same initial shape of the helical elastic element 404 (i.e., a narrow circumference).

[0133] According to a further aspect of the invention, which is illustrated in FIG. 9, the temperature controlled fluid is provided through the guiding catheter 410 and released in the vicinity of the shape memory catheter tip. It is noted that the shape memory catheter tip can be cooled or heated, by this temperature controlled fluid, to temperatures other than the temperature of the environment in which the tip is placed. When the supply of temperature controlled fluid stops, then the shape memory catheter tip is either cooled or heated to this environment temperature.

[0134] Reference is now made to FIG. 11, which is a schematic illustration of a catheter tip, generally referenced 450, constructed and operative in accordance with a further preferred embodiment of the present invention. Tip 450 is made of a hollow SMA tube which enables the flow of temperature controlled fluid therethrough. The tip 450 is inserted in the body of the patient over a guiding wire 460.

[0135] According to this aspect of the invention, one end tip 450 is opened. The temperature controlled fluid which is provided to the tip, travels through the tip 450 and is released through the tip end 452, in the vicinity of the shape memory catheter tip 450.

[0136] Reference is now made to FIG. 12, which is a schematic illustration of a catheter tip, generally referenced 470, constructed and operative in accordance with another preferred embodiment of the present invention. shape memory catheter tip 470 includes a guiding tip 472, which extends at the front of the tip 470. The shape memory catheter tip 470 is guided in the tubular organ to its destination, using this guiding tip, without the requirement of a guiding wire. It is noted that a guiding wire can also be used as further guiding assistance.

[0137] It is noted that each part of a catheter, according to the invention, and especially the catheter tip, can be coated with an anti-coagulation material such as Heparin.

[0138] Reference is now made to FIG. 13, which is a schematic illustration of a catheter tip, generally referenced 500, and energy transfer means, generally referenced 502, constructed and operative in accordance with a further preferred embodiment of the present invention.

[0139] Energy transfer means include two concentric conduits 504 and 506, where conduit 504 is the outer conduit and conduit 506 is the inner conduit. The outer conduit 504 transfers the temperature controlled fluid to the tip 500 and the inner conduit 506 receives temperature controlled fluid from the tip and transfers it outside. It is noted that the directions of flow within the two conduits 504 and 506 can be swapped so that the inner conduit 506 transfers the temperature controlled fluid to the tip 500, while the outer conduit 504 transfers the temperature controlled fluid from the tip 500.

[0140] The entire assembly is generally inserted via a guiding catheter 510. It is noted that the concentric structure of the conduits provides reduced surface area and volume, so that a narrower guiding catheter can be used. Furthermore, the concentric structure provides a smoother shape, so that the movement of the conduits within the guiding catheter is easier.

[0141] According to another aspect of the present invention, a catheter is provided, which includes an integral SMA tip and a balloon mechanism.

[0142] According to this aspect of the invention, the balloon is used to enlarge the diameter of the tip, while the SMA characteristics of the tip is used to reduce its diameter to its original size.

[0143] Reference is now made to FIG. 14A, which is an illustration of a catheter system, generally referenced 600, constructed and operative in accordance with a further preferred embodiment of the present invention.

[0144] System 600 includes a main catheter 608, an integrally connected catheter tip 604, a balloon mechanism 602 and a controller 606.

[0145] The tip 604 is a coil shaped element, made of a hollow tube, having a shape which is generally similar to the shape of tip 104, described hereinabove in conjunction with FIGS. 4A and 4B. It is noted that tip 604 has a large diameter shape when in the Martensite state and narrow diameter shape when in the Austenite state.

[0146] Reference is further made to FIGS. 14B, 14C, 14D, 14E and 14F, which are illustrations of parts of system 600, inserted in an artery, generally referenced 610.

[0147] With reference to FIGS. 14B and 14C, the balloon 602 is inserted in the tip 604, so that the helical shape of the tip surrounds the balloon. The tip 604 and balloon 602 are inserted into an area, generally referenced 614, to be treated within artery 610 (FIG. 14B). As can be seen, the area, which is to be treated, is stenosed, thereby reducing the blood flow there through.

[0148] At this stage, tip 604 has a shape having a narrow diameter. Hence, the tip 604 is easily inserted in the artery 610. The physician locates the tip 604 in the artery 610 at the desired location, which, as can be seen from the drawing, suffers a major blockage 612, which significantly reduces flow there thorough.

[0149] Then, the physician operates the balloon mechanism and inflates the balloon 602. As the balloon 602 expands, it applies pressure on the tip 604, thereby enlarging its diameter (FIG. 14C). The inflation of the balloon 602 also pushes artery 610 walls and the blockage 612, outwardly, so as to increase the inner diameter thereof.

[0150] When the Balloon enlarges the artery 610 and tip 604 to the desired size, the physician operates the balloon mechanism so as to deflate the balloon (FIG. 14D). According to the present invention, the balloon deflates, thereby reducing the diameter of its shape, while the SMA tip maintains its large diameter shape, thereby supporting the walls of the treated section of the artery 610.

[0151] It is noted that term artery is presented only by way of example and that the present invention is applicable for any type of tubular organ.

[0152] As the balloon deflates, blood resumes its flow within the treated section of the artery, in both radial and axial directions. It is noted that since the tip 604 supports the walls of the treated section of the artery 610, then the physician can start deflating the balloon right after it reached the desired diameter. Accordingly, the time period in which the balloon blocks the treated section, thereby preventing blood flow, is significantly minimized to the order of few seconds. It is noted that at this stage, the balloon 602 can be removed from the treated section and for that matter, from the body of the patient. According to the present invention, the tip can remain in the artery, supporting the artery walls, for as long as required, to stabilize the shape of the artery in its new condition (FIG. 14D). The time period in which the tip supports the artery can be in the order of second, minutes, hours and even days.

[0153] When the artery is fixed in its new shape, then the physician operates system 600 so as to heat up the tip 604, thereby changing it into the Austenite state. Accordingly, the tip changes its shape by reducing its overall diameter (FIG. 14E). It is noted that the heating up of the tip can be performed in a plurality of ways such as pumping hot fluid through the tip 604. The arrows within the tip 604 (FIG. 14E) denote the flow of such fluid.

[0154] According to another aspect of the invention, the tip is heated by applying fluid to the vicinity of the tip, as shown in conjunction with FIG. 9.

[0155] According to a further aspect of the invention, when the transition temperature is located below body temperature, then the heating of the tip can be performed by use of the body temperature.

[0156] According to yet another aspect of the invention, when the transition temperature is located above body temperature, then the cooling of the tip can be performed by use of the body temperature.

[0157] According to yet a further aspect of the invention, the tip is heated by applying electric current therethrough, for example, as shown in conjunction with FIG. 8 and as will be described in detail hereinbelow, in conjunction with FIG. 15.

[0158] As the tip 604 shrinks, it is no longer attached to the walls of the artery and the physician can easily remove it from the treated section of the artery (FIG. 14F).

[0159] At this stage, the physician can remove the catheter from the body of the patient. However, it is noted that the physician can also move the catheter tip 604 to a new location within the artery system, which can be treated sequentially. Hence, the present invention incorporates an advantage over the prior art, where the catheter tip 604 can be used for more than one treatment.

[0160] It is noted that for an additional treatment, a new balloon can be provided and inserted to the tip 604. Alternatively, if the balloon 602 structure permits it, then the balloon 602 can be reused in the other location.

[0161] According to the present invention, when catheter tip is reused in a new location, it is first cooled down so as to move to a Martensite state, where it can be deformed by an inflating balloon. Such a cool down procedure can be performed by pumping cold fluid therethrough or by applying cold fluid to the vicinity of the tip.

[0162] Reference is now made to FIG. 15, which is an illustration of a combined catheter tip and balloon assembly, generally referenced 650, constructed and operative in accordance with another preferred embodiment of the present invention.

[0163] Assembly 650 includes a catheter tip 652, a balloon 654 and electrical heating means 656. The catheter tip 652 is made of solid SMA material, and has the shape of a general helix. The electrical heating means include two electrical wires 662A and 662B and two contact rings 660A and 660B.

[0164] The Balloon 654 is inserted within the tip 652. Contact rings 660A and 660B are each connected to the tip 652 at a different location, which defines an electrical path therebetween. The wires 662A and 662B are connected to contact rings 660A and 660B, respectively.

[0165] When the balloon 654 is inflated, it pushes the tip structure outwardly, thereby enlarging the diameter of the helix. It is noted that at this stage the tip is maintained in a Martensite state.

[0166] The wires 662A and 662B apply electrical current onto the tip 652, thereby heating it. When the tip 652 heats-up, it moves from the Martensite state to the Austenite state, thereby reducing the diameter of the helix.

[0167] It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather the scope of the present invention is defined only by the claims which follow.