TECHNICAL FIELD

[0001] The invention relates to medical systems and more specifically to devices for extracting implants such as pacemaker electrical leads.

BACKGROUND

[0002] Aging people tend to be more inclined to various heart conditions. Such heart conditions may for instance include bradycardia which is a slow abnormal heart beat or arrhythmia which can combine a heartbeat that is either too fast, too slow or with an irregular rhythm. Other heart conditions such as those derived from heart attacks may greatly impair a subject. In these situations, pacemaker devices or implantable defibrillators are implanted in a subject and configured to regulate the abnormal heartbeats the subject may experience. Cardiac leads or wires are used to connect the pacemaker or defibrillator devices to various tissues within the human body to stimulate or defibrillate heart tissues. However, as the pacemaker or defibrillator device reaches its useful life, these electrical leads need to be removed from the body. Sometimes this task is made difficult by the presence of fibrotic and calcified tissues that become attached to the lead and therefore prevent its safe removal.

[0003] In other applications, central catheters connected to an implantable delivery port may be implanted in a subject. The central catheters are used to deliver drug therapy, such as chemotherapy or morphinotherapy, to be further distributed throughout the body or to targeted cells, tissues or organs, for example the heart chamber. When a central catheter reaches its useful life, it needs to be removed from the body. Sometimes this task is made difficult by the presence of fibrotic and calcified tissues that become attached to the central catheter and therefore prevent its safe removal.

[0004] There is therefore a need for an improved device adapted to remove or help removing a medical device implanted into the body of a subject. SUMMARY

[0005] According to a first broad aspect, there is provided an extraction device for removing an implanted medical object, the device comprising: an elongated catheter body extending between a proximal end and a distal end along a longitudinal axis, the elongated catheter body defining an elongated aperture along the longitudinal axis, the elongated aperture being sized and shaped to receive the implanted medical object therein, the elongated catheter body further defining at least one waveguide receiving aperture extending between the proximal and distal ends of the elongated body; and at least one mechanical waveguide receivable in the at least one waveguide receiving aperture, the at least one mechanical waveguide extending between a proximal end operatively connectable to a mechanical wave generator and a distal end, the at least one mechanical waveguide configured to propagate at least one mechanical wave therealong.

[0006] In one embodiment, the elongated catheter body comprises a first hollow and elongated body and a second hollow and elongated body, the second hollow and elongated body defining the elongated aperture for receiving the implanted medical object therein, the second hollow and elongated body being inserted into the first hollow and elongated body and a space between an external face of the second hollow and elongated body and an internal face of the first hollow and elongated body defines the at least one waveguide receiving aperture.

[0007] In one embodiment, the first and second hollow and elongated bodies are tubular.

[0008] In one embodiment, the first and second hollow and elongated bodies are concentric.

[0009] In one embodiment, a distal end of the first hollow and elongated body protrudes outwardly from a distal end of the second hollow and elongated body.

[0010] In another embodiment, a distal end of the second hollow and elongated body protrudes outwardly from a distal end of the first hollow and elongated body.

[0011] In one embodiment, the at least one mechanical waveguide comprises a plurality of mechanical waveguides each positioned within the space defined between an external face of the second hollow and elongated body and an internal face of the first hollow and elongated body.

[0012] In one embodiment, the plurality of mechanical waveguides are positioned circumferentially about the second hollow and elongated body.

[0013] In one embodiment, the plurality of mechanical waveguides are arranged as rows about the second hollow and elongated body.

[0014] In another embodiment, the elongated catheter body is a solid elongated body provided with the elongated aperture and the at least one waveguide receiving aperture.

[0015] In one embodiment, the at least one mechanical waveguide comprises plurality of mechanical waveguides and the at least one waveguide receiving aperture comprises a plurality of waveguide receiving apertures each for receiving a respective one of the plurality of mechanical waveguides.

[0016] In one embodiment, the plurality of waveguide receiving apertures are circumferentially positioned about the elongated aperture.

[0017] In one embodiment, a distal end of the solid elongated body is beveled.

[0018] In one embodiment, the at least one mechanical waveguide is longer than the elongated catheter body.

[0019] In one embodiment, the at least one mechanical waveguide is fixedly received in the at least one waveguide receiving aperture.

[0020] In another embodiment, the at least one mechanical waveguide is movably received in the at least one waveguide receiving aperture.

[0021] In one embodiment, the elongated aperture is sized and shaped to receive an electrical lead of a pacemaker therein.

[0022] In one embodiment, the elongated catheter body is made of a medical grade biocompatible material. [0023] In one embodiment, the elongated catheter body is made of an acoustically insulating material.

[0024] In one embodiment, the at least mechanical waveguide is made of a medical grade biocompatible material.

[0025] According to another broad aspect, there is provided a system for removing an implanted medical object, the device comprising: the above-described extraction device, and a generator for generating mechanical waves, the generator being operatively connectable to the proximal end of the at least one mechanical waveguide for propagating the mechanical waves along the at least one mechanical waveguide.

[0026] In one embodiment, the generator is configured for generating mechanical pulses.

[0027] It should be understood that a mechanical wave may have an arbitrary amplitude, duration, waveform, frequency, and/or the like. For example, a mechanical wave may have a high/low amplitude, a short/long duration, different waveforms, and any frequency content.

[0028] For the purpose of the present description, a mechanical pulse should be understood as a short duration mechanical wave. The duration of a mechanical pulse is of the order of about l/fc.

[0029] Furthermore, a mechanical waveguide should be understood as a waveguide adapted to propagate mechanical waves or pulses along its length. In the present description, the expressions“waveguide”,“mechanical waveguide” and“transmission member” may be used interchangeably. The shape and dimension of a waveguide may vary. For example, a waveguide may have a cylindrical shape. The diameter of the waveguide may be constant along its length. Alternatively, the diameter of the waveguide may vary along its length. For example, the diameter of a waveguide may decrease along its length so that the waveguide corresponds to a taper.

[0030] In one embodiment, a mechanical waveguide may comprise a single elongated element adapted to propagate mechanical waves and/or pulses therealong. In another embodiment, a mechanical waveguide may comprise a plurality of elongated elements each adapted to propagate mechanical waves and/or pulses therealong.

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Having thus generally described the nature of the invention, reference will now be made to the accompanying drawings, showing by way of illustration example embodiments thereof and in which:

[0032] Figure 1 illustrates a system for removing an implanted medical device surrounded by calcified tissue, the system comprising a mechanical wave generator and an implant extraction catheter device having a single mechanical waveguide adapted to propagate mechanical waves, in accordance with an embodiment;

[0033] Figure 2 illustrates the implant extraction catheter device having a single mechanical waveguide of Figure 1; and

[0034] Figure 3 illustrates an implant extraction catheter device provided with five mechanical waveguides, in accordance with an embodiment.

DETAILED DESCRIPTION

[0035] In the following there is described an extraction device for removing from a body a medical device implanted or inserted into the body or helping removing a medical device implanted into the body. For example, the extraction device may be used for removing a cardiac lead or wire, a catheter, or the like. More particularly, the extraction device may be used for removing an implanted medical device to which fibrotic and calcified tissues are attached.

[0036] Figure 1 illustrates one embodiment of an extraction catheter device 100 that may be used to extract a medical device implanted into a subject’s body. In the illustrated embodiment, the extraction device 100 is used for extracting a cardiac lead 102 surrounded by fibrotic and/or calcified tissue 104 and having its distal end fixed to the fibrotic and/or calcified tissue 104. The extraction device 100 comprises a first elongated body 110 and a second elongated body 112 which both extend along a same longitudinal axis. In the illustrated embodiment, the first and second elongated bodies 110 and 112 each have a tubular shape and are concentric so that the second elongated body 112 is positioned within the first elongated body 110.

[0037] The extraction device 100 further comprises a mechanical waveguide 114 for propagating mechanical waves such as high amplitude and short duration mechanical pulses or shock waves therealong. The mechanical waveguide 114 is inserted between the first and second elongated bodies 110 and 112.

[0038] The mechanical waveguide 114 extends between a proximal end operatively connectable to a mechanical wave generator 116 and a distal end. It should be understood that the proximal end of the mechanical waveguide 114 may be fixedly connected to the mechanical wave generator 116. Alternatively, the proximal end of the mechanical waveguide 114 may be removably connected to the mechanical wave generator 116 as long as the mechanical waves or pulses generated by the mechanical wave generator 116 are at least partially coupled into the mechanical waveguide 114.

[0039] The first and second elongated bodies 110 and 112 also each extend between a respective proximal end and a respective distal end. While in the illustrated embodiment the proximal end of the first elongated body 110 and that of the second elongated body 112 are secured to the mechanical wave generator 116, it should be understood that the proximal end of the first elongated body 110 and/or the proximal end of the second elongated body 112 may not be connected or secured to the mechanical wave generator 116.

[0040] While in the illustrated embodiment, the first and second elongated bodies 110 and 112 and the mechanical waveguide 114 are provided with the same length, it should be understood that the length of the first elongated body 110 and/or the length of the second elongated body 112 may be shorter than that of the mechanical waveguide 114.

[0041] In the illustrated embodiment, the distal end of the mechanical waveguide 114, the distal end of the first elongated body 110 and the distal end of the second elongated body 112 are coplanar. However, other configurations may be possible. For example, the distal end of the mechanical waveguide 114 may protrude from the distal ends of the first and second elongated bodies 110 and 112 which may be coplanar. In another example, the distal end of the second elongated body 112 and the distal end of the mechanical waveguide 114 may be coplanar and both protrude from the distal end of the first elongated body 110. In a further embodiment, the distal end of the first elongated body 110 and the distal end of the mechanical waveguide 114 may be coplanar and the distal end of the second elongated body 112 may protrude from the distal ends of the first elongated body 110 and the mechanical waveguide 114..

[0042] In one embodiment, the mechanical waveguide 114 has a fixed position relative to the first and second elongated bodies 110 and 112. In one embodiment, the mechanical waveguide 114 is maintained in a fixed position within the space between the external lateral wall/face of the second elongated body 112 and the internal lateral wall/face of the first elongated body 110 by being sandwiched between the first and second elongated bodies 110 and 112 via compression forces. For example, the distance between the internal wall of the first elongated body 110 and the external wall of the second elongated body 112 may be equal to the diameter of the mechanical waveguide, or less than the diameter of the mechanical waveguide if the first elongated body 110 is made of a stretchable material.

[0043] In another embodiment, the mechanical waveguide 114 is secured to the internal wall of the first elongated body 110 and the external wall of the second elongated body 112. For example, adhesive such as glue or silicone may be used for securing the mechanical waveguide 114 to the first and second elongated bodies 110 and 112.

[0044] In another embodiment, the mechanical waveguide 114 may translate and/or rotate relative to the first and second elongated bodies 110 and 112. In this case, the first and second elongated bodies 110 and 112 have a fixed relative position. For example, the first and second elongated bodies may be fixedly secured together thanks to arms extending between the internal face of the first elongates body 110 and the external wall of the second elongated body 112. In this case, the mechanical waveguide 114 is positioned between two adjacent arms.

[0045] While the first and second elongated bodies 110 and 112 are concentric, it should be understood that other configurations may be possible. [0046] While the first and second elongated bodies 110 and 112 are each provided with a circular cross-section, it should be understood that other cross-section shape are possible. For example, the cross-section of the first and second elongated bodies 110 and 112 may have a triangular shape, a rectangular shape, a hexagonal shape or the like. It should be understood that the shape and cross-sectional of at least the distal section of the second elongated body 112 adjacent to the distal end thereof are chosen based on the shape and cross-sectional size of the lead 102 so that the lead may be inserted into the distal section of the second elongated body 102.

[0047] While the illustrated mechanical waveguide 114 has a cylindrical shape, it should be understood that the mechanical waveguide 114 may be provided with any other adequate shape as long as it may be inserted between the first and second elongated bodies 110 and 112. It should also be understood that the mechanical waveguide 114 is adapted to propagate the mechanical waves or pulses generated by the mechanical wave generator 116.

[0048] In use, the extraction device 100 is first mounted around the lead 102 by inserting the lead 102 into the second elongated body 112. The extraction device 100 is further pushed to further insert the lead 102 into the second elongated body 112 until the distal end of the extraction device 100 abuts against the calcified tissue 104. The distal end of the mechanical waveguide 114 is then adjacent to the calcified tissue 104 or in physical contact with the calcified tissue 104.

[0049] The mechanical wave generator 116 is then actuated to generate mechanical waves such as pulses having a high amplitude and short duration. The mechanical waves then propagate along the mechanical waveguide 114 from its proximal end operatively connected to the mechanical wave generator 116 towards its distal end. When reaching the distal end of the mechanical waveguide 114, the mechanical waves are transmitted to the calcified tissue 104. In one embodiment, only a portion of the mechanical waves are transmitted at the distal end of the mechanical waveguide 114.

[0050] The transmitted mechanical waves reaching the calcified tissue allow for cracking, eroding, cleaving, tunneling, crossing and/or breaking the calcified tissue 104 surrounding the lead 102. [0051] In an embodiment in which the mechanical wave generator 116 generates mechanical pulses, the mechanical pulses arriving at the distal end of the mechanical waveguide 114 creates a movement. The created movement of the distal end of the mechanical waveguide 114 may also be used for cracking, eroding, cleaving, tunneling, crossing and/or breaking the calcified tissue 104 in addition to the transmitted mechanical pulses when the distal end of the mechanical waveguide is abutted against the calcified tissue 104. The created movement may be along the longitudinal axis of the mechanical waveguide 114. Alternatively, the movement may be perpendicular to the longitudinal axis, i.e. along the perpendicular axis. In a further embodiment, the created movement of the distal end of the mechanical waveguide may be a combination of movements along both the longitudinal axis and perpendicular axis of the mechanical waveguide 114.

[0052] During this movement, the distal end of the mechanical waveguide 114 may first move towards the tissue 104 surrounding the lead 102 and then moves back into its initial position. It should be understood that the movement may be inverted depending on the polarity of the mechanical pulses reaching the distal end of the mechanical waveguide 114. For instance, the distal end of the mechanical waveguide 114 may first move away from the tissue 104 and then move towards the tissue 104.

[0053] In one embodiment, a train of successive mechanical pulses are generated at a given repetition rate during a given period of time. In one embodiment, the repetition rate may be substantially constant in time. In another embodiment, the repetition rate may vary in time. Repetitive and successive distinct mechanical pulses transmitted at the distal end of the mechanical waveguide 114 may trigger a jackhammer movement which may create cracks, erosion, cleavages, tunnels and/or breaks therein for penetrating into the tissue 104 when the distal end of the mechanical waveguide 114 abuts against the tissue 104.

[0054] As the tissue 104 is detached from the lead 102, the extraction device is further pushed so as to further insert the lead 102 into the second elongated body 112 in order to further remove the remaining tissue 104.

[0055] In one embodiment, once the lead 102 has been inserted into the second elongated body 112, the extraction device 100 is rotated about its longitudinal axis to vary the angular position of the distal end of the mechanical waveguide 114 in order to remove the tissue 104 located around the circumference of the lead 104.

[0056] While the extraction device 100 comprises two hollow and elongated bodies 110 and 112, Figure 2 illustrates one embodiment of an extraction body 200 which comprises a solid and cylindrical elongated body 202 extending between a proximal end 204 and a distal end 206. The elongated body 202 is provided with a lead receiving aperture 208 and a waveguide receiving aperture 210. The lead receiving aperture 208 extends from the distal end 206 of the elongated body 202 along a given length thereof. The shape and cross-sectional dimension of the lead receiving aperture 208 are chosen based on the shape and cross- sectional dimension of the lead to be removed and the given length of the lead receiving aperture 208 is chosen based on the length of the lead so that the lead may at least partially inserted into the lead receiving aperture 208. The waveguide receiving aperture 210 extends between the proximal and distal ends 204 and 206 of the elongated body 202. The shape and cross-sectional size of the waveguide receiving aperture 210 are chosen based on the shape and cross-sectional size of a mechanical waveguide so that the mechanical waveguide may be inserted into the waveguide receiving aperture 210.

[0057] In one embodiment, the mechanical waveguide is inserted into the waveguide receiving aperture 210 so that the distal end of the mechanical waveguide be flushed or coplanar with the distal end 206 of the elongated body 202. In another embodiment, the mechanical waveguide may be inserted into the waveguide receiving aperture 210 so that its distal end protrudes from the distal end 206 of the elongated body 202.

[0058] In one embodiment, the mechanical waveguide once inserted into the waveguide receiving aperture 210 may translate relative to the elongated body 202. In another embodiment, the mechanical waveguide is fixedly secured within the waveguide receiving aperture 210.

[0059] Once the mechanical waveguide has been inserted into the waveguide receiving aperture 210, the extraction device 200 may be used in a manner similar to the extraction device 100. [0060] While the distal end of the first elongated body 110 and that of the second elongated body 112 is orthogonal to the longitudinal axis of the extraction body 100, it should be understood that the distal end of the first elongated body 110 and/or the distal end of the second elongated body 112 may be provided with any other adequate shape. For example, the distal end of the first elongated body 110 and/or the distal end of the second elongated body 112 may be provided with a sharp-edged or beveled shape to enhance the penetration of the extraction device 100 into the calcified tissue 104.

[0061] While the extraction devices 100 and 200 are each provided with a single mechanical waveguide, it should be understood that an extraction device may comprise more than one mechanical waveguide.

[0062] Figure 3 illustrates one embodiment of an extraction device 300 that may be used to extract an implanted medical device. In the illustrated embodiment, the extraction device 300 is used for extracting a cardiac lead 302 surrounded by fibrotic and/or calcified tissue (not shown). The extraction device 300 comprises a first elongated body 310 and a second elongated body 312 which both extend along a same longitudinal axis. In the illustrated embodiment, the first elongated body 310 and the second elongated body 312 each have a tubular shape and are concentric so that the cardiac lead 304 is positioned within the second elongated body 310.

[0063] The extraction device 300 further comprises four mechanical waveguides 320, 322, 324 and 326 for propagating mechanical waves such as high amplitude and short duration mechanical pulses or shock waves therealong. The mechanical waveguides 320, 322, 324 and 326 are each inserted between the first elongated body 310 and the second elongated body 312, each at a respective angular position. In the illustrated embodiment, the mechanical waveguides 320, 322, 324 and 326 are evenly distributed around the second elongated body 312. However, it should be understood that the mechanical waveguides 320, 322, 324 and 326 may be non-evenly distributed around the second elongated body 312.

[0064] While in the illustrated embodiment the mechanical waveguides 320, 322, 324 and 326 are identical, it should be understood that at least two of the mechanical waveguides 320, 322, 324 and 326 may be different, i.e. they may have a different cross-sectional shape, they may have a different cross-sectional size, they may be made of different materials, etc.

[0065] Each mechanical waveguide 320, 322, 324, 326 extends between a proximal end operatively connectable to a respective mechanical wave generator or to the same mechanical wave generator and a distal end. It should be understood that the proximal end of the mechanical waveguide 320, 322, 324, 326 may be fixedly connected to the mechanical wave generator. Alternatively, the proximal end of the mechanical waveguide 320, 322, 324, 326 may be removably connected to the mechanical wave generator as long as the mechanical waves or pulses generated by the mechanical wave generator(s) are at least partially coupled into the mechanical waveguides 320, 322, 324 and 326.

[0066] The first elongated body 310 and the second elongated body 312 also each extend between a respective proximal end and a respective distal end. While in the illustrated embodiment, the first elongated body 310 and the second elongated body 312 and the mechanical waveguides 320, 322, 324 and 326 are provided with the same length, it should be understood that the length of the first elongated body 310 and/or the length of the second elongated body 312 may be shorter than that of the mechanical waveguides 320, 322, 324 and 326.

[0067] In the illustrated embodiment, the distal ends of the mechanical waveguides 320, 322, 324 and 326, the distal end of the first elongated body 310 and the distal end of the second elongated body 312 are coplanar. However, other configurations may be possible as described above with respect to Figure 1. For example, the distal ends of the mechanical waveguides 320, 322, 324 and 326 may protrude from the distal end of the first elongated body 310 and the distal end of the second elongated body 312.

[0068] In one embodiment, the mechanical waveguides 320, 322, 324 and 326 each have a fixed position relative to the first elongated body 310 and the second elongated body 312. In one embodiment, the mechanical waveguides 320, 322, 324 and 326 are maintained in a fixed position within the space between the external lateral wall/face of the second elongated body 312 and the internal lateral wall/face of the first elongated body 310 by being sandwiched between the first elongated body 310 and the second elongated body 312 via compression forces. For example, the distance between the internal wall of the first elongated body 310 and the external wall of the second elongated body 312 may be equal to the diameter of the mechanical waveguides 320, 322, 324 and 326, or less than the diameter of the mechanical waveguides 320, 322, 324 and 326 if the first elongated body 310 is made of a stretchable material.

[0069] In another embodiment, the mechanical waveguides 320, 322, 324 and 326 are secured to the internal wall of the first elongated body 310 and the external wall of the second elongated body 312. For example, adhesive such as glue may be used for securing the mechanical waveguides 320, 322, 324 and 326 to the first elongated body 310 and the second elongated body 312.

[0070] In another embodiment, the mechanical waveguides 320, 322, 324 and 326 may translate relative to the first elongated body 310 and the second elongated body 312. In this case, the first elongated body 310 and the second elongated body 312 have a fixed relative position. For example, the first elongated body 310 and the second elongated body 312 may be fixedly secured together thanks to arms extending between the internal face of the first elongates body 310 and the external wall of the second elongated body 112. In this case, the mechanical waveguides 320, 322, 324 and 326 are positioned between two respective adjacent arms.

[0071] While the first elongated body 310 and the second elongated body 312 are concentric, it should be understood that the first elongated body 310 and the second elongated body 312 may not be concentric, e.g. when one of the mechanical waveguides 320, 322, 324 and 326 has a diameter that is greater than the diameter of the other mechanical waveguides 320, 322, 324 and 326.

[0072] While the mechanical waveguides 320, 322, 324 and 326, the first elongated body 310 and the second elongated body 312 are each provided with a circular cross-section, it should be understood that other cross-section shape are possible. For example, the cross- section of the second elongated body 312 may be hexagonal or oval as long as the lead 302 may be received within the second elongated body 312.. [0073] In use, the extraction device 300 is first mounted around the lead 302 by inserting the lead 302 into the second elongated body 312. The extraction device 300 is further pushed to further insert the lead 302 into the second elongated body 312 until the distal end of the extraction device 300 abuts against the calcified tissue for example. The distal end of the mechanical waveguides 320, 322, 324 and 326 is then adjacent to the calcified tissue or in physical contact with the calcified tissue.

[0074] The mechanical wave generator(s) is(are) then actuated to generate mechanical waves such as pulses having a high amplitude and short duration. The mechanical waves then propagate along the mechanical waveguides 320, 322, 324 and 326 from their proximal end operatively connected to the mechanical wave generator(s) towards their distal end. When reaching the distal end of the mechanical waveguides 320, 322, 324 and 326, the mechanical waves are transmitted to the calcified tissue. In one embodiment, only a portion of the mechanical waves are transmitted at the distal end of the mechanical waveguides 320, 322, 324 and 326.

[0075] The transmitted mechanical waves reaching the calcified tissue allow for cracking, eroding, cleaving, tunneling, crossing and/or breaking the calcified tissue surrounding the lead 302.

[0076] In an embodiment in which the mechanical wave generator generates mechanical pulses, the mechanical pulses arriving at the distal ends of the mechanical waveguides 320, 322, 324 and 326 creates a movement at the distal end of each mechanical waveguide 320, 322, 324, 326. The created movement of the distal ends of the mechanical waveguides 320, 322, 324 and 326 may also be used for cracking, eroding, cleaving, tunneling, crossing and/or breaking the calcified tissue in addition to the transmitted mechanical pulses when the distal ends of the mechanical waveguides 320, 322, 324 and 326 are abutted against the fibrotic and/or calcified tissue.

[0077] In one embodiment, a train of successive mechanical pulses are generated at a given repetition rate during a given period of time. In one embodiment, the repetition rate may be substantially constant in time. In another embodiment, the repetition rate may vary in time. Repetitive and successive distinct mechanical pulses transmitted at the distal ends of the mechanical waveguides 320, 322, 324 and 326 may trigger a jackhammer movement at the distal end of each mechanical waveguide 320, 322, 324, 326 which may create cracks, erosion, cleavages, tunnels and/or breaks therein for penetrating into the tissue when the distal ends of the mechanical waveguides 320, 322, 324 and 326 abut against the tissue.

[0078] As the tissue is detached from the lead 302, the extraction device 300 is further pushed so as to further insert the lead 302 into the second elongated body 312 until the distal end of the lead 302 be inserted into the second elongated body 312.

[0079] In one embodiment, once the lead 302 has been inserted into the second elongated body 312, the extraction device 300 is rotated about its longitudinal axis to vary the angular position of the mechanical waveguides 320, 322, 324 and 326 relative to the tissue 302 in order to remove the tissue located around the circumference of the lead 302.

[0080] It should be understood that the number and the disposition of the mechanical waveguides 320, 322, 324 and 326 may vary. For example, the distal end of one of the mechanical waveguides 320, 322, 324 and 326 may protrude away from the distal ends of the other mechanical waveguides 320, 322, 324 and 326..

[0081] Similarly to the extraction device 200, the extraction device 300 may be embodied as a cylindrical body comprising a central lead receiving aperture for receiving therein the lead 302 and four waveguide receiving apertures each for receiving therein a respective mechanical waveguide.

[0082] In one embodiment, the elongated bodies 110, 112, 202 and 310 and the second elongated body 312 are made of medical grade biocompatible material. In the same or another embodiment, their material is acoustically insulating. Furthermore, they may be made of a flexible material to correspond to a catheter sheath.

[0083] In one embodiment, the mechanical waveguide(s) is(are) made of medical grade biocompatible material such as stainless steel, nitinol or a titanium alloy, although other materials may be used. [0084] In an alternative embodiment, the extraction device 300 may comprise more than one layer of mechanical waveguides distributed between the second elongated body 312 and the body 310 and forming a plurality of rows of mechanical waveguides. The mechanical waveguides of the first row may be evenly distributed around the circumference of the second elongated body 312 and in physical contact therewith. The next rows may thus be concentrically positioned around the first row and may comprise a different number of mechanical waveguides. The mechanical waveguides may further be adjacent or spaced apart from one another to avoid coupling therebetween. Further, in order to prevent contact between adjacent rows, the extraction catheter 300 may further comprise an elongated sheath made of an acoustically insulating material, inserted between two adjacent rows of mechanical waveguides to isolate the mechanical waveguides from different rows.

[0085] In the following there is described an exemplary mechanical pulse generator that can be used for generating mechanical pulses for weakening a calcified tissue.

[0086] The mechanical pulse generator is configured to generate high amplitude and short duration mechanical pulses.

[0087] In one embodiment, the high amplitude and short duration mechanical pulse produced by the pulse generator has a center frequency fc comprised between about 20 kHz and about 10 MHz. In one embodiment, the duration of the mechanical pulse generated by the mechanical pulse generator is less than 10 microseconds, preferably around 1 microsecond, and may have an amplitude greater than 5 MPa, preferably greater than 10 MPa. In some embodiments, such values for the duration and amplitude of the mechanical pulse optimize the drilling efficiency of the jackhammer movement at the distal end of the mechanical waveguide when a series or sequence of mechanical pulses is generated.

[0088] The pulse generator may comprise one broadband source and/or one narrow band source. The narrow or broadband source may be an electromechanical transducer that converts electrical energy into mechanical energy.

[0089] In one embodiment, the pulse generator comprises a plurality of broadband sources and/or a plurality of narrowband sources. The outputs of several sources covering adjacent frequency bands are combined to generate the mechanical pulse. In one embodiment, the outputs of at least two broadband sources, i.e., the mechanical pulses generated by the at least two broadband sources, are combined. In another embodiment, the outputs of at least one broadband source and at least one narrowband source are combined.

[0090] In another embodiment, the mechanical pulse is generated by focusing, via a pulse focusing device, the output of a large broadband source toward a focal zone. It should be understood that the outputs of more than one large broadband source may be concurrently focused on the same focal zone.

[0091] In one embodiment, the pulse focusing device is a spatial concentrator, an acoustic lens, an acoustic mirror or the like.

[0092] In a further embodiment, a high amplitude mechanical pulse may be generated by spatially and/or temporally combining mechanical pulses or waves sequentially emitted by a single broadband source using a reverberating cavity. It should be understood that the mechanical pulses generated by more than one broadband source may be spatially and/or temporally combined together by a reverberating cavity to provide the high amplitude mechanical pulse.

[0093] In still another embodiment, high amplitude mechanical pulses may be generated by using a dispersive medium and/or a dispersive geometry to combine the component waves emitted sequentially by a single broadband source. It should be understood that the mechanical pulses generated by more than one source may be combined together using the dispersive medium or the dispersive geometry.

[0094] In still a further embodiment, the mechanical pulse may be amplified. In an embodiment in which a temporal concentrator is present, the mechanical wave becomes a mechanical pulse of which the amplitude is greater than that of each component wave of the mechanical wave. In an embodiment in which a spatial concentrator is present, the amplitude of a mechanical pulse or wave is increased while propagating through the spatial concentrator. In another embodiment in which a spatial concentrator is present, different mechanical waves or pulses are combined to generate a greater amplitude mechanical wave or pulse, i.e. the different mechanical waves or pulses add to each other.

[0095] In one embodiment, the amplitude of the mechanical pulse when reaching the distal end of the mechanical waveguide is comprised between about 1 MPa and about 1000 MPa. In one embodiment, the duration of the short duration mechanical pulse when reaching the distal end of the transmission member is in the order of l/fc, where fc is the center frequency of the wave. In one embodiment, the center frequency fc is comprised between 20 kHz and 10 MHz, preferably between 100 kHz and 2 MHz.

[0096] The embodiments described above are intended to be exemplary only. The scope of the invention is therefore intended to be limited solely by the appended claims.