Abstract:
The invention relates to an instrument, particularly a medical device for minimal invasive surgery, that comprises an inflatable balloon ( 104 ) to which at least one movable tool element ( 105 ) is attached. In preferred embodiments, the tool element is a filamentary flexible structure like a wire ( 105 ) or an optical fiber. Moreover, a plurality of such tool elements is preferably arranged circumferentially around the balloon ( 104 ) constituting for example a cage-like grab that can be opened or closed by inflating or deflating the balloon ( 104 ). Furthermore, pulling a cord attached to the balloon ( 104 ) additionally allows to change the balloon configuration.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to an instrument with an inflatable balloon that is particularly suited for medical procedures like minimal invasive surgery, and to a system comprising such an instrument. Moreover, it relates to a method for moving a tool element in e.g. minimal invasive surgery. 
       BACKGROUND OF THE INVENTION 
       [0002]    From the U.S. Pat. No. 6,106,550 a catheter is known that comprises a radially folded tip and a plurality of axially extending optical fibers which are attached to the walls of the catheter. An annular balloon at the tip of the catheter can be inflated to unfold and extend the catheter tip in order to adapt it to the size of a blood vessel to be treated. 
       SUMMARY OF THE INVENTION 
       [0003]    Based on this background, it was an object of the present invention to provide alternative means for the manipulation of objects in for example minimal invasive surgery, wherein it is desirable that tool elements can be moved over a significant range with comparatively simple means. 
         [0004]    This object is achieved by an instrument according to claim  1 , a system for minimal invasive surgery according to claim  11 , and a method according to claim  12 . Preferred embodiments are disclosed in the dependent claims. 
         [0005]    The instrument according to the present invention may serve for any purpose in e.g. science, industrial production, robotics etc. It is particularly suited for medical procedures like minimal invasive surgery. The instrument comprises the following components:
   a) An inflatable balloon as it is known for example from the field of medical catheters, where such balloons are used to dilate vessels or to place and extend stents. In principle, the inflatable balloon may have any topology, though simple spheroidal or toroidal topologies are preferred. Typical materials for the inflatable balloon are physiologically acceptable and may e.g. comprise a latex rubber.   b) At least one tool element with a movable section that is solely attached to the wall of the balloon. While said section is typically attached to the outer side of the balloon, there may also be applications in which it is attached to the inner side of the balloon.   
 
         [0008]    The described instrument has the advantage that its tool element can be moved over a large range because it is with at least one section solely attached to the wall of the balloon such that this section can in principle completely follow the movement of said wall. When the balloon is inflated or deflated, the tool element will therefore shift and typically also change its orientation accordingly. In contrast to this, tool elements like the optical fibers described in U.S. Pat. No. 6,106,550 are more or less firmly embedded in some carrier structure that severely restricts their movement and largely decouples it from the associated balloon. 
         [0009]    While in general there are no restrictions as to the size and function of the tool element, said tool element will have in many applications a substantially filamentary and flexible configuration. Such a tool element can have a performance like a finger that can be bent or stretched if the associated balloon is deflated or inflated. 
         [0010]    In a particular embodiment of the invention, the (filamentary, flexible) tool element comprises a wire. Said wire may preferably have a free end portion that projects from the balloon and that can be used to manipulate objects. 
         [0011]    According to a further development of the aforementioned embodiment, the wire has an end portion with a barb, a bending or the like, wherein said end portion preferably projects freely from the balloon. Designing the end portion in such a way optimizes the tool element for certain functions. If for example a bent tool element cooperates with at least one counterpart (e.g. a further similar tool element), it can be used like a pince gripper for grabbing an object. 
         [0012]    In another embodiment of the invention, the (filamentary) tool element comprises an optical fiber. Light can then be conducted through the fiber and emitted from its end into the surroundings for purposes of e.g. illumination or for cutting tissue with a laser beam. By inflating or deflating the balloon, the emission of the optical fiber can selectively be focused within a large range. 
         [0013]    Of course the described embodiments of the invention with wires and optical fibers as tool elements can be combined. Thus a balloon may for example carry an alternating sequence of optical fibers and wires on its outer wall, wherein the fibers can illuminate the operating field of the wires. 
         [0014]    While the invention was up to now described including the case of an instrument with just one tool element, preferred embodiments of the invention comprise a circumferential arrangement of a plurality of (similar or differently designed) tool elements around the balloon. Thus a radial symmetry of the arrangement around the axis of the balloon can be achieved. If wires are used as tool elements, at cage-like grabber can be realized. If optical fibers are used as tool elements, their outlets can be positioned on a circle of variable radius, and their emissions can be adjusted continuously between a convergent and a divergent direction. 
         [0015]    In another embodiment of the invention, the instrument comprises a rigid body to which a further section of the tool element is attached. In an optional modification of this design, the balloon is at least partially connected to said rigid body. If the tool element is attached both to the rigid body and the flexible balloon, a flexion of the tool element can be realized. The rigid body can serve in this case as a stationary base to which for example the body of a wire or of an optical fiber is attached, while the tip of this tool element moves according to the filling state of the balloon. 
         [0016]    In a further development of the invention, the instrument comprises a manipulating element that is fixed with one end to the wall of the balloon for selectively exerting forces onto said wall. The manipulating element may particularly be located within the balloon and be fixed to the inner wall of the balloon, and it may optionally be realized as a cord or a rod. Pulling on such a cord or pulling or pushing on such a rod can then selectively change the shape of the balloon without changing its state of inflation. Thus a further degree of freedom is achieved for the manipulation of the tool element attached to the balloon, which increases the functionality of the instrument. 
         [0017]    The instrument may optionally further comprise a tubular element in which the balloon is disposed. The tubular element provides a shelter and a kind of skeleton for the balloon. The balloon is preferably not fixed to the tubular element but axially movable with respect to it. 
         [0018]    The invention further relates to a system for minimal invasive surgery, said system comprising an endoscope or a catheter and a medical instrument of the kind described above (i.e. an instrument with an inflatable balloon and at least one tool element with a movable section that is solely attached to the wall of the balloon). 
         [0019]    Moreover, the invention relates to a method for moving a tool element of an instrument for minimal invasive surgery, wherein a movable section of the tool element is attached to a balloon and wherein said balloon is inflated or deflated to produce a corresponding movement of the tool element. 
         [0020]    The system and the method for minimal invasive surgery comprise the essential features of an instrument of the kind described above. Therefore, reference is made to the preceding description for more information on the details, advantages and improvements of that system and method. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter. These embodiments will be described by way of example with the help of the accompanying drawings in which: 
           [0022]      FIG. 1  shows schematically an axial section (top) through and a top view (bottom) of an instrument with a cage-like grab formed from wires; 
           [0023]      FIG. 2  shows an enlarged view of the tip area of the instrument that is encircled in  FIG. 1 , wherein the grab is in its neutral configuration with the wires extending axially; 
           [0024]      FIG. 3  shows an axial section (top left), a top view (bottom left), and an enlarged view of the tip (right) of the instrument of  FIG. 1  in a state in which the balloon is inflated and the grab is opened; 
           [0025]      FIG. 4  shows in a similar representation as  FIG. 3  the instrument when the balloon is deflated and the grab is closed; 
           [0026]      FIG. 5  shows schematically an axial section through an instrument with a plurality of optical fibers arranged circumferentially around a balloon; 
           [0027]      FIG. 6  shows an enlarged view of the tip area of the instrument that is encircled in  FIG. 5 , wherein the balloon is in its neutral configuration with the optical fibers extending axially; 
           [0028]      FIG. 7  shows an enlarged view of the tip of the instrument of  FIG. 6  in a state in which the balloon is inflated and the optical fibers have a divergent configuration; 
           [0029]      FIG. 8  shows in a similar representation as  FIG. 7  the instrument when the balloon is deflated and the optical fibers converge. 
       
    
    
       [0030]    Like reference numbers or numbers differing by integer multiples of  100  refer in the Figures to identical or similar components. 
       DETAILED DESCRIPTION OF EMBODIMENTS 
       [0031]    In the following, the invention will be explained with respect to an application at catheters. The invention can however also be used in other medical applications (e.g. in endoscopes and the working area of endoscopes) as well as in a non-medical applications. 
         [0032]    A catheter is an important tool for modern minimal invasive interventions. It is essentially a tube that can be inserted into a body cavity or blood vessel, thereby allowing easy access to critical positions of the body. Catheters are being used for diagnostics and therapy of predominantly cardiovascular diseases, e.g. placing stents in blood vessels, but also for urinary and neurovascular applications. 
         [0033]    When a loose object has to be removed in a minimal invasive intervention, it has to be grasped. If this object is very fragile, soft, very hard, slippery, slimy or small, it is often hard to grab it with a pliers without pressing it into pieces. 
         [0034]    In other applications of catheters, light coming from optical fibers is used to coagulate tissue for example in the cardiac area. Aiming the light onto a location and spreading the light over a variable surface poses a non-trivial problem in this case. 
         [0035]      FIGS. 1 to 4  illustrate a first embodiment of an instrument  100  that addresses the above mentioned issues. Said instrument  100  comprises the following components: 
         [0036]    An inflatable balloon  104  that is shown in  FIGS. 1 and 2  in its “neutral” or resting state in which it has substantially a cylindrical shape and in which its distal tip has the same diameter as its body. At its proximal end, the balloon  104  comprises an inlet  102  that it is continued by a channel leading to some controllable supply (not shown) of gas or liquid, e.g. a physiological solution, by which the balloon can be inflated or the deflated. Balloons of the shown type are principally known from for example percutaneous angioplasty. 
         [0037]    A plurality of (in the shown example  12 ) linearly extending wires  105 , wherein a subsection of these wires  105  is attached to the balloon  104 . The wires are further equally distributed over the circumference of the balloon  100  and for instance provided with tips  106  that are radially bent inwards to the axis A of the balloon. In general, the ends  106  can have a variety of shapes. Depending on the application, they can for example be smooth (as shown) or have a barb. 
         [0038]    A rigid body  103 , which is substantially cylindrical in the depicted case, wherein a large part of the wall of the balloon  104  is attached to this rigid body. When the balloon is inflated for deflated, the rigid body  103  will keep its shape (cf.  FIGS. 3 and 4 ). 
         [0039]    A pulling cord  101  that runs within the balloon  104  along the axis A and that is fixed to the tip of the balloon. 
         [0040]    The wires  105  of the described instrument  100  realize a cage-like grab that can be manipulated by inflating or deflating the balloon and additionally by pulling the cord  101 .  FIGS. 1 and 2  show in this respect the neutral state of the grab with the wires extending linearly. 
         [0041]      FIG. 3  shows the state of the instrument  100  in which an overpressure expands the balloon  104 , which lets the wires  105  diverge and leads to an opening of the grab. 
         [0042]    In contrast to this,  FIG. 4  shows the situation when the balloon  104  is deflated by an underpressure, which leads to a convergent configuration of the wires  105  that closes the grab. Additionally or alternatively, the closed configuration of the grab can also be achieved by pulling the cord  101  which leads to an indentation in the tip of the balloon  104 . In this case a cavity in which the instrument is located can be kept open by the inflated balloon  104  during a grabbing action. 
         [0043]    With the described movement of the wires  105 , loose cut tissue and other loose objects can be grabbed by changing the pressure inside the balloon. During the grabbing action, the overall position of the instrument will not change. Only the grabbing wires  105  will move inwards to enclose the object. 
         [0044]      FIGS. 5 to 8  show a second embodiment of an instrument  200  that comprises an inflatable balloon  204  with filamentary, flexible tool elements  205  being partially fixed to its outside. In general, the inflatable balloon  204 , its inlet  202 , and a pulling cord  201  are analogous to the corresponding elements in the first embodiment and need therefore not be described again. The filamentary, flexible tool elements are now however not constituted by wires but by optical fibers  205  through which laser light can be conducted from a proximally located light source (not shown) to the outlets  206  at the distal ends of the fibers  205 . Moreover, the balloon with the attached optical fibers is located in this embodiment within a catheter  210 , which provides a hollow flexible tube in which the balloon  204  is free to move axially. 
         [0045]    Again, the inflation or deflation of the balloon  204  and/or a pulling at the cord  201  can be used to alter the shape of the balloon and thus also the direction of the optical fibers  205  and their outlets  206 .  FIGS. 5 and 6  show in this respect the neutral configuration in which the optical fibers are axially stretched and the emitted light is more or less straight forward concentrated on a spot with about the diameter of the catheter  210  (wherein the actual size of the spot depends on the distance between the end of the catheter and the illuminated area). 
         [0046]      FIG. 7  shows a state in which the balloon  204  is pushed over a certain distance out of the catheter  210  and expanded by an overpressure, letting the optical fibers  205  diverge. In this way a larger area can be illuminated. If the expansion is larger than the area illuminated by one fiber, a circular illumination will appear with a dark spot in the middle. 
         [0047]      FIG. 8  shows a state in which the middle of the balloon tip is pulled backwards by the cord  201  and/or in which the balloon is deflated. The fibers  205  will then bend inwards to the centre of the catheter. In this way all fibers can be aimed at the same focus point on the axis A of the instrument. 
         [0048]    Aiming the fibers  205  towards a predetermined point can be done by directing the catheter  210  appropriately with existing catheter aiming solutions. The described variable convergence or divergence of the fibers  205  can then particularly be used to adjust the illumination area. Thus spreading the fibers will illuminate a larger area, while aiming them to one point creates a large concentration of light at said point. 
         [0049]    The described instrument  200  can be used in medical catheter applications for illuminating tissue for several medical reasons, e.g. for coagulating or burning tissue. 
         [0050]    Finally it is pointed out that in the present application the term “comprising” does not exclude other elements or steps, that “a” or “an” does not exclude a plurality, and that a single processor or other unit may fulfill the functions of several means. The invention resides in each and every novel characteristic feature and each and every combination of characteristic features. Moreover, reference signs in the claims shall not be construed as limiting their scope.