Abstract:
The present invention describes a device for intracorporal, minimal-invasive treatment of a patient, comprising a working instrument that can be introduced into a body cavity of the patient for carrying out a treatment step, wherein a distal end of the introduced working instrument defines an intracorporal working area, and at least one image pick-up unit for picking up an image of the intracorporal working area, further comprising positioning means for orienting an optical axis of the image pick-up unit in dependency on a spatial position of the intracorporal working area, wherein the positioning means comprise a guide shaft, in which the working instrument is guided, and wherein the image pick-up unit is pivotably fixed at an intracorporal portion of the guide shaft. The positioning means have a holder pivotably fixed to the intracorporal portion of the guide shaft, the image pick-up unit being arranged at the holder in a distance from a location where the holder is linked to the guide shaft, such that the image pick-up unit is intracorporally pivotable into a working position, in which the optical axis runs angularly to a longitudinal center axis of the guide shaft and points to the longitudinal center axis.

Description:
CROSS REFERENCE TO PENDING APPLICATION 
     The present application is a continuation of pending International Patent Application PCT/EP01/01039 filed on Jan. 31, 2001, which designates the United States and claims priority of German Patent Application 100 04 264 filed on Feb. 1, 2000. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to a device for intracorporal, minimal-invasive treatment of a patient, comprising a working instrument that can be introduced into a body cavity of the patient for carrying out a treatment step, wherein a distal end of the introduced working instrument defines an intracorporal working area, and at least one image pick-up unit for picking up an image of the intracorporal working area, further comprising positioning means for orienting an optical axis of the image pick-up unit in dependency on a spatial position of the intracorporal working area, wherein the positioning means comprise a guide shaft, in which the working instrument is guided, and wherein the image pick-up unit is pivotably fixed at an intracorporal portion of the guide shaft. 
     Such a device is known from U.S. Pat. No. 5,166,787. 
     In the minimal-invasive, surgical treatment of patients, working instruments are brought to the location to be treated in the body of the patient merely through one or several small incisions. The visual control of the working steps to be carried out in the body of the patient is done endoscopically. An example for a minimal-invasive standard operation is the laparoscopical colecystectomy. In this procedure, three small openings are cut into the abdominal area of the patient. One of the openings serves for introducing an endoscope with a video camera, the image of which can be seen on a monitor by the treating physician. Working instruments, like e.g. scissors, forceps or the like, are introduced through the other two openings. 
     When the operation is carried out, the endoscope is, today, usually handled by an assistant physician, who tracks the endoscope to changes and displacements of the working area so far that the treating physician always has the working instruments in his visual field. Such camera assistance requires, however, a very good coordination between the treating physician and the assistant physician, what often is problematic in practice. Moreover, the necessary camera assistance requires more staff in carrying out the operation, which has a negative effect on the costs. 
     In DE 195 29 950 C1, a device was, thus, suggested, in which the camera assistant is replaced by an automatically controlled robot that is arranged outside the body of the patient. For the control of the robot, the image picked up by the endoscope camera is evaluated with reference to the position of working instrument or instruments appearing in the image picked up. The working instruments are marked with colors to this end, so that they can be identified by means of the proposed image treatment algorithm. 
     It is true that such a robot control can generally replace the assistant physician required as in the past, it is, however, expensive from the technical point of view and has, moreover, further disadvantages. In particular, the robot system requires a very large mechanical holder, which takes a relatively large space over the patient. This limits the freedom of movement for the treating physician over the patient. Apart from that, the sterilization of the relatively large robot device is difficult. The assembly and disassembly of such a device also requires relatively much time, what has a negative effect on the costs and the efficiency particularly in standard operations. 
     From U.S. Pat. No. 5,166,787 mentioned at the outset, an endoscope with a video camera arranged on its distal end is known, wherein the video camera is movable as a whole with respect to the distal end of the endoscope shaft after being introduced into the body cavity to be examined of the patient. The video camera can be pivoted about an axis running parallel with respect to the longitudinal axis of the shaft, which forms a body-own axis of the video camera, in a plane transverse to the longitudinal direction of the shaft out of the longitudinal axis of the shaft. The viewing direction of the video camera remains, in this procedure, in every pivot position of the video camera parallel with respect to the longitudinal center axis of the shaft. In another embodiment, the video camera is additionally pivotable, about a pivot axis running transversely with respect to the longitudinal direction of the shaft, again, about a video camera-own axis. In this procedure, the viewing angle of the video camera is changed with respect to the longitudinal axis of the shaft, however, only such viewing directions are created, which form a very acute angle with the longitudinal axis of the shaft, or such viewing directions, which are facing away from the longitudinal center axis of the shaft and are, thus, not useful for the endoscope when used in an operation. In other words, it is not possible to reach the same or at least similar perspective observation conditions with this known endoscope as with an endoscope that was introduced into the body cavity via an additional access. 
     Neither the known endoscope nor the video camera, moreover, have positioning means by which the viewing direction and/or the image field of the video camera can automatically be tracked to certain displacements or shiftings of the intracorporal working area. Thus, also for this known device a manual positioning with the disadvantages already mentioned is necessary. 
     It is, thus, an object of the present invention to provide a device of the type mentioned at the outset, by which at least similar perspective viewing conditions can be reached like with an endoscope that is introduced into the body cavity via an additional access. 
     SUMMARY OF THE INVENTION 
     According to the invention, the object underlying the invention is achieved by a device for intracorporal, minimal-invasive treatment of a patient, comprising: 
     a working instrument that can be introduced into a body cavity of said patient for carrying out a treatment step, said working instrument having a distal end defining an intracorporal working area when said working instrument is introduced in said body cavity; 
     at least one image pick-up unit for picking up an image of said intracorporal working area, said image pick-up unit having an optical axis; and 
     positioning means for orienting said optical axis of said image pick-up unit in dependency on a spatial position of said intracorporal working area, said positioning means further comprising: 
     a guide shaft in which said working instrument is guided, said guide shaft having an intracorporal portion, and 
     a holder pivotably fixed to said intracorporal portion of said guide shaft, wherein said image pick-up unit is arranged at said holder in a distance from a location where said holder is linked to said guide shaft, such that said image pick-up unit is intracorporally pivotable into a working position, in which said optical axis runs angularly to a longitudinal center axis of said guide shaft and points to said longitudinal center axis. 
     The device according to the invention differs from the known device in particular by the fact that the image pick-up unit is fixed at the guide shaft via a holder, and, due to the pivotability of the holder, can be pivoted away from the guide shaft, i.e. can be spaced apart from the guide shaft. In that way, the viewing direction can be positioned under a larger angle with respect to the longitudinal axis of the guide shaft, which corresponds to the perspective viewing conditions of an endoscope being introduced through an additional opening into the body cavity, what is welcomed by the physician. By the coupling of the image pick-up unit with the intracorporal portion of the guide shaft, it is moreover possible, as is in the following described in more detail, that the image pick-up unit can automatically follow at least a part of the movements of the working instrument, without a robot or a corresponding device outside of the body cavity being necessary. It is therefore practically a seeing working instrument. The device according to the invention is consequently considerably smaller and more space saving and less cost-expensive than common devices with an extracorporal positioning device. 
     By means of the present invention, practically a “distal end of an endoscope” is coupled with the working instrument, which can be positioned with a perspective viewing direction onto the working area, just as if a whole endoscope was introduced into the body cavity through an additional opening. 
     In preferred embodiments of the invention, which are described in more detail in the following, a separate holder for the image pick-up unit outside the body cavity of the patient can even be completely omitted, so that in this case no additional space at all over the patient is necessary. The freedom of movement for the treating physician is then not limited at all anymore. 
     In addition, with the smaller device the effort for assembly and disassembly is reduced, what has a positive effect on the efficiency and the handling in practical use. 
     Finally, the sterilization of the device according to the invention is easier due to the smaller dimensions. In spite of all that, the device of the invention has all advantages of an automatic tracking system, so that, altogether, a considerable cost saving in minimal-invasive treatments of patients is possible. Apart from that, the risk of an unintended contamination of the image pick-up unit by tissue contact is reduced. Furthermore, also shorter operation times can be reached due to the improved handling, what results in less strain and a lesser operation risk for the patient. 
     In minimal-invasive operations, as already mentioned at the outset, two incisions are created, wherein an active working element, e.g. scissors is introduced, through the first incision, from the sight of the physician usually the “right” one, and, a passive or more passive working instrument, e.g. a holding instrument, is introduced through the other one, i.e. from the sight of the physician the “left” one. For the device according to the invention, it is particularly preferred in this sense, if the image pick-up unit is coupled with the more passive working instrument via the guide shaft. 
     The object mentioned before is therefore completely achieved. 
     In a preferred embodiment, the holder has at least one pivot arm that is articulatedly fixed to the intracorporal portion. 
     By this measure, the device with the functions and effects according to the invention mentioned before can be configured particularly simple in design in order to configure a coupling of the image pick-up unit on the guide shaft for obtaining perspective viewing conditions. 
     In a particularly simple preferred embodiment, the image pick-up unit is arranged at the free end of the at least one pivot arm in such a way that the optical axis of the image pick-up unit runs approximately perpendicular to the longitudinal axis of the pivot arm and points to the longitudinal center axis of the guide shaft. 
     In this embodiment, only one articulation is necessary in an advantageous manner, namely the one via which the at least one pivot arm is connected to the guide shaft and via which the image pick-up unit can then be pivoted out from the guide shaft for adjusting a perspective viewing angle, in order to adjust the desired perspective angle between the longitudinal axis of the guide shaft or the working instrument and the image pick-up unit. 
     In such a simple embodiment of the device according to the invention, it is advantageous to integrate even more than one image pick-up unit in order to obtain a video stereo system for an improved stereoscopic representation and reproduction. 
     In the embodiment mentioned before, it is further preferred if the pivot arm has an adjustable length. 
     This measure has the advantage that in a displacement of the working instrument in axial direction the angle between the optical axis and the image pick-up unit and the longitudinal axis of the working instrument can be held constant by shortening or extending the pivot arm in the one-axis embodiment of the articulation mechanism. The pivot arm can be designed in a telescope-like manner to this end, for example. 
     In another preferred embodiment of the invention, the holder has a one-axis or a multi-axis articulation mechanism. 
     This measure has the advantage that with increasing number of the axes of the articulation mechanism the number of degrees of freedom of movement of the image pick-up unit increases with reference to the guide shaft. As a result, the image pick-up unit can be oriented onto the working area, if a multi-axis articulation mechanism is used. 
     In another preferred embodiment, the image pick-up unit is pivotable into a resting position at the guide shaft, in which an outer cross-sectional contour of the image pick-up unit is arranged in an essentially congruent manner with respect to an outer cross-sectional contour of the guide shaft. 
     This measure has the advantage that the image pick-up unit can be introduced together with the guide shaft, i.e. through the same opening, into the body cavity of the patient. As a result, e.g. in laparoscopical colecystectomy, one of the three incisions required up to now can be dispensed with. This results in a lesser traumatization of the patient, what results, again, in a lesser risk. In other applications, e.g. in tube sterilization, even only one incision is required with the perspectively seeing instrument of the invention. 
     In another embodiment of the invention, the image pick-up unit is fixable via an intracorporally activatable coupling mechanism at the guide shaft. 
     In this embodiment of the invention, the initially separate image pick-up unit can be intracorporally fixed at the guide shaft. By this measure, it is possible to introduce the image pick-up unit separately from the guide shaft into the body cavity of the patient, e.g. over an own incision opening. The measure has the advantage that both the image pick-up unit and the guide shaft each for itself can be realized in a larger dimension, so that altogether there is more construction space available. This is particularly advantageous in view of the image pick-up unit, since a larger construction space can, for example, receive more optical fibers and, thus, allows a higher light intensity. 
     In another embodiment of the invention, the positioning means comprise a mechanically constrained coupling between the working instrument and the image pick-up unit. 
     A mechanically constrained coupling allows in a simple way an automatic tracking of the image pick-up unit, without additional actuating drives or sensors being necessary. As a result, this embodiment of the invention can be realized with very low costs and, moreover, in a very robust manner. The latter is particularly advantageous for the practical use in working and in sterilizing. 
     In this connection, it is preferred if the positioning means have locking means for an at least partial axial immobilization of the working instrument with respect to the guide shaft. 
     This measure represents the simplest tracking between the image pick-up system and the working area, as the image pick-up unit connected with the guide shaft via the holder, by the axial fixation of the working instrument with respect to the guide shaft, is entrained by every axial movement of the working instrument. The pivoted position of the holder is maintained in the simplest case, so that also the perspective viewing direction remains unchanged. The perspective observation angle can, before, be fixed by pivoting the holder and, thus, the image pick-up unit, such that the point of the working instrument which defines the working area rests approximately in the image center. The working instrument is then immobilized e.g. at the proximal side at the guide shaft by means of the locking means, such that it is preferably rotationally movable in the guide shaft, but can, however, be axially moved only in connection with the guide shaft. In order to achieve a complete axial fixation of the working instrument at the guide shaft, in the simplest case, an annular groove can be provided in the guide shaft in which runs a pin which is preferably spring-loaded and which is located at the working instrument. By such a locking, it is guaranteed that the working area lies in the viewing area of the image pick-up unit in spite of a movement of the working instrument. 
     In this connection, it is further preferred if the locking means are configured in such a way that the working instrument is axially freely displaceable with respect to the guide shaft within predetermined limits, but axially entrains the guide shaft, if the working instrument is displaced beyond the predetermined axial limits. 
     It may be interfering when the image pick-up unit always follows the working instrument when it is axially moved, so that no visual registration of the movement of the instrument is possible. By the embodiment described before, it is now possible to move the instrument axially with respect to the guide shaft within predetermined limits, without the guide shaft and, with it, the image pick-up unit being also moved. The limits mentioned before are preferably adjusted in such a way that they just correspond to the distance between the entering of the point of the working instrument into the image field and the outgoing of the point of the working instrument from the image field. Only if the point of the working instrument would leave the image field, the locking means become active and entrain, then, the guide shaft and, with it, the image pick-up unit. Such locking means may be realized by a broader annular groove in the guide shaft, in which runs a pin arranged at the working instrument which is axially shorter compared to the axial length of the annular groove. 
     In comparison to the very simple tracking mentioned before, it is also preferred if the working instrument is axially freely displaceable with respect to the guide shaft, and that the holder has coupling means, which can be brought in engagement with the working instrument in such a way that, when the working instrument is displaced relative to the guide shaft, the holder is pivoted, in order to track the optical axis to the working area. 
     In this embodiment, thus, an axial relative displacement between the working instrument and the guide shaft results in a pivoting of the holder at the guide shaft and, thus, in a change of the viewing direction of the image pick-up unit, wherein the coupling causes the viewing direction of the image pick-up unit to be always directed onto the working area. 
     In a further embodiment of the invention, the positioning means comprise an actuator unit for pivoting the image pick-up unit and a sensor unit coupled therewith, by which a current position of the working area can be determined. 
     This measure may be used alternatively to a mechanically constrained coupling. The measure is, however, preferably used complementary to a mechanically constrained coupling, wherein the mechanically constrained coupling on the one hand and the sensor/actuator unit on the other hand control different degrees of freedom of movement of the image pick-up unit. The measure has the advantage that a sensor/actuator unit allows an electronic positioning, which results in a higher flexibility and a larger scope of arrangements. This holds true both for the design of the device according to the invention and for its practical use. 
     In a further embodiment of the measure mentioned before, the sensor unit comprises measuring means for determining a relative position of the working instrument with reference to the guide shaft. 
     The measuring means may e.g. comprise a bar code, a resistance measurement, an angle decoder or a position sensor on the basis of infrared, ultrasound or electromagnetic fields. The measure has the advantage that such position sensors are sufficiently known per se in the prior art, so that a position determination by a position sensor is very simply possible. The reference to the guide shaft allows, moreover, a reference that is always constant and exactly known. 
     In a further embodiment, which can be used both alternatively and complementary to the measure mentioned before, the sensor unit comprises image-processing means for identification of the distal end of the working instrument in the image picked up. 
     This measure has the advantage that additional measuring devices, like e.g. in the form of a position sensor, can be dispensed with, whereby the necessary construction space can also be saved. Complementary to a position sensor, a redundancy is achieved which allows an increase of the reliability and measuring accuracy. 
     Preferably, in the working position, the optical axis encloses an angle of at least 10°, particularly preferably between 20° and 700°, with the longitudinal center axis of the guide shaft. 
     Also preferably, in the working position, the image-entering opening of the image pick-up unit is in a lateral distance from the guide shaft, which is larger than approximately 1 cm. 
     Due to these measures, the operating physician achieves an optimal viewing angle onto the working area, what considerably facilitates the carrying out of the operation. From an angle of about 10°, the operating physician achieves a sufficient lateral view (perspective) on the distal end of the working instrument. The angle range between 20° and 70° is optimal. The measure is particularly advantageous if the image pick-up unit is introduced via the same incision into the body cavity of the patient as the guide shaft, as the operating physician would otherwise have to accept disadvantages with respect to the viewing angle in this case. 
     In a further embodiment of the invention, the image pick-up unit is an integrated video probe, which provides an electrical image signal of the working area. 
     Preferably, the video probe is a stereo video probe, which allows for the operating physician an, again, better perspective stereoscopic image, in particular in connection with the embodiment according to claim 3. The measure has generally the advantage that an electric image signal, in particular in digital form, can be transported without or with relatively slight quality losses, because no illustration errors like in lens systems occur. As a result, the quality of the image reproduction is very high in this measure. Just for stereo image pick-up units, the invention has the additional advantage that double images and/or distortion are reduced, as an always constant, optimal working distance and, thus, a constant 3D perspective are maintained. 
     In connection with the measure mentioned before, it is preferred if the image picked up by the image pick-up unit is telemetrically transmitted. 
     It is advantageous herewith that the image picked up by the video sensor can be transmitted into the proximal direction without expensive cable systems. In connection with the one-axis or multi-axis articulation mechanism mentioned before for coupling the image pick-up unit onto the guide shaft, this is particularly advantageous, because no cables have to be led through the articulation or the articulations of the pivot mechanism. Also the susceptibility for damages and an untightness due to the implementation of cables is considerably reduced by the measure mentioned before. 
     It is further preferred if the image pick-up unit has a transmitter, the transmitted image signals of which are received by a receiver. 
     The integration of a transmitter into the image pick-up unit, i.e. into the video sensor, has the advantage that cables for image transmission between the video sensor and the receiver can be completely dispensed with, so that the image pick-up unit can be completely encapsulated, wherein problems of tightness can be completely removed. 
     It is further preferred if the receiver or at least its antenna is arranged at the intracorporal portion of the guide shaft. 
     While it is also possible to do the telemetric transmission from the image pick-up unit through the abdominal wall to an extracorporally arranged receiver, the measure mentioned before has the advantage that also frequency ranges of higher frequency can be used, which, otherwise, would be dampened by the abdominal wall. 
     In a further preferred embodiment, an illuminating device is arranged at the image pick-up unit, which has preferably at least one light emitting diode. 
     This has the advantage that also for a light supply to the working area, optical fibers can be completely dispensed with, which cannot be led over the articulation mechanism and, thus, would have to be led through the guide shaft. A light emitting diode at the image pick-up unit has, however, the essential advantage that the direction of the illumination and the viewing direction of the image pick-up is the same, so that, when the image pick-up unit is tracked to a movement of the working instrument, also the illumination is optimally tracked. 
     In a further preferred embodiment, the image pick-up unit has a source of energy, e.g. a battery or an accumulator, for its supply. 
     Altogether, thus, a completely autonomous image pickup unit is created, if necessary, with a light source for illuminating the working area, the image pick-up unit being advantageous in connection with the positionability of the image pick-up unit according to the invention. 
     Taking CMOS video sensors as a basis, it is possible in the future that such autonomous image pick-up units can be manufactured as one-way products, so that problems of cleaning and recycling will not arise any more. 
     In an alternative embodiment of the measure mentioned before, the image pick-up unit is an optical element, which provides an optical image signal of the working area. 
     The optical element can be, for example, an ordered fiber bundle, a lens system and/or a mirror system. The measure has the advantage that such passive elements can be realized in very small dimensions and with usual, controllable techniques. This is particularly advantageous if the image pick-up unit is to be introduced via the same opening into the body cavity of the patient as the guide shaft. 
     In a further embodiment of the invention, the guide shaft has a guide channel that is open on both ends for receiving and guiding exchangeable working instruments. 
     This measure allows the operating physician to use different working instruments in the same guide shaft, wherein the image pick-up unit can always be constantly directed onto the defined working area. As a result, the operating physician can orient very quickly and simply even if the working instrument is changed. Alternatively to this measure, however, it is also possible to couple the different working instruments each with an own guide shaft. 
     As already mentioned before, according to embodiments mentioned before, the working instrument is guided in the guide shaft movably in axial direction. 
     This measure has the advantage that the operating physician can manipulate the working instrument in the working area as usual and, in doing so, can perform e.g. cuts with scissors in the usual way. 
     In a further embodiment, the working instrument is immovable in radial direction in the guide shaft. 
     This measure has the advantage that the guide shaft directly follows radial movements of the working instrument, which is a particularly simple and effective constrained coupling. When the working instrument rotates in the guide shaft, the guide shaft is preferably not entrained, so that the viewing direction of the image pick-up unit remains unchanged, as is provided in another preferred embodiment. 
     In comparison to a complete radial fixation, it can, however, be advantageous, again, if the working instrument has a certain radial play with respect to the guide shaft, so that, in a lateral movement of the working instrument transverse with respect to the longitudinal axis of the working instrument, the image pick-up unit is not entrained within certain limits and the image field remains unchanged, and an entrainment occurs only if the movement exceeds the limits, as it was described before for the axial mobility. 
     In a further embodiment of the invention, the image pick-up unit has means for modification of a picked up image sector. 
     In particular, the image pick-up unit of this embodiment has a zoom objective, by which the image of the working area can be enlarged within predetermined limits, without changing the spatial distance between the image pick-up unit and the working area. In that way, the operating physician obtains a further possibility to adjust a visual range that is optimal for the performance of the treatment, to be more precise, without having to change the position of the working instrument. 
     In a further embodiment of the invention, an illuminating device is arranged on the intracorporal portion of the guide shaft. 
     This measure has also the advantage that the working area is well illuminated. In combination with the measure mentioned before, due to the different illumination directions, different shadows are created, which cause an increase of the depth indentation or of the stereo effect. 
     It is to be understood that the features mentioned above and those yet to be explained below can be used not only in the respective combinations indicated, but also in other combinations or in isolation, without leaving the scope of the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Embodiments of the invention are shown in the drawings and will be explained in more detail in the description below. In the drawings: 
     FIG. 1 shows a first embodiment of a device according to the invention; 
     FIG. 2 shows an enlarged and partly sectioned portion of the device according to FIG. 1; 
     FIG. 3 shows a guide shaft with an image pick-up unit according to a second embodiment of the invention; 
     FIG. 4 shows the guide shaft in FIG. 3 along the line IV—IV; 
     FIG. 5 shows a guide shaft with an image pick-up unit in resting position according to a third embodiment of the invention; 
     FIG. 6 shows the guide shaft from FIG. 5, wherein the image pick-up unit is pivoted in a working position; 
     FIG. 7 shows a guide shaft and an image pick-up unit according to a second embodiment of the invention; 
     FIG. 8 shows another embodiment of a device according to the invention; 
     FIG. 9 shows a representation of a locking mechanism between a guide shaft of the device in FIG. 8 and a working instrument guided in same; and 
     FIG. 10 shows an embodiment of a locking mechanism modified in comparison to FIG. 9 between a guide shaft of the device in FIG. 8 and a working instrument. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     In FIG. 1, a device according to the invention is altogether designated with the reference numeral  10 . The device  10  serves for the performance of an operation in the abdomen  12  of a patient. 
     Device  10  comprises a guide shaft  14 , which is introduced via a trocar  16  through the abdominal wall  18  of the patient into the abdomen  12 . Alternatively, guide shaft  14  can also be part of trocar  16 . 
     An image pick-up unit is designated with the reference numeral  20 , which is fixed via a holder  21  at an intracorporal portion  23  of guide shaft  14 , holder  21  having a multi-axis articulation mechanism  22 , which has two articulation axes in the present case. The image pick-up unit is in this case an integrated, miniaturized video probe, which supplies an electrical image signal to an image reproduction unit being arranged outside abdomen  12  via an electrical connection not shown. 
     The image pick-up unit or video probe  20  can advantageously also have a transmitter, in order to transmit telemetrically the image taken by video sensor  20  in the form of transmitted image signals. For receiving these image signals, a receiver is arranged at intracorporal portion  23  of guide shaft  14 . 
     A working instrument, which is in the present case a grasping forceps as an example, is designated with the reference numeral  24 . Generally, working instrument  24  can be any instrument, which is required for the performance of the minimal-invasive operation in abdomen  12  of the patient. 
     Video probe  20  has in the present embodiment a zoom objective  26  with a variable focal distance, which is indicated by an arrow  28 . 
     The optical axis of video probe  20  is designated with the reference numeral  30 , the optical axis running in the working position shown under an angle  32  with respect to the longitudinal center axis  34  of guide shaft  14 . 
     The working area of working instrument  24  is designated with the reference numeral  36 , the working area being defined by the distal end  38  of working instrument  24 . 
     Video probe  20  is connected in such a way with intracorporal portion  23  of guide shaft  14 , via articulation mechanism  22  and via measures shown in more detail in the following, that its optical axis  30  and, thus, its viewing angle can always follow automatically spatial changes of working area  36 . In order to explain this function, reference is additionally made to FIG. 2 in the following. The same elements as in FIG. 1 are designated with the same reference numerals. 
     As can be seen in FIG. 2, articulation mechanism  22  is fixed at guide shaft  14  via an articulation  40 , wherein articulation  40  is the point where holder  21  is linked to guide shaft  14 . Image pick-up unit  20  is arranged at holder  21  in a distance from this link, in the embodiment shown at the outer free end. Articulation mechanism  22  has a lever arm  42 , which projects into the inner part of guide shaft  14  via articulation  40 . At the free end of lever arm  14 , a spring-loaded sphere  44  is shown, which is an example for a locking mechanism not described in detail. 
     Working instrument  24  is releasably connected with lever arm  42  via sphere  44  or via the locking mechanism represented more generally thereby. This connection has as result that a movement of working instrument  24  into the direction of an arrow  46 , i.e. a movement in axial direction, tilts articulation mechanism  22  into the direction of an arrow  48 . In that way, optical axis  30  of video probe  20  is moved into the direction of an arrow  50 , so that the viewing angle of video probe  20  finally follows the axial movement of working instrument  24 . 
     In a movement of working instrument  24  against the direction of arrow  46 , the viewing angle of video probe  20  is displaced in reversed direction, so that video probe  20  altogether is automatically tracked to a displacement of working area  36 , due to the mechanically constrained guiding via lever arm  42  and sphere  44 . 
     In radial direction, i.e. in the direction of an arrow  52  in FIG. 2, working instrument  24  has no degree of freedom of movement with respect to guide shaft  14 . As a result, guide shaft  14  follows every movement of working instrument  24  in the direction of arrow  52 . As can easily be understood, by this measure, the viewing direction of video probe  20  is also tracked to a movement of working area  36 . However, a certain radial play between the working instrument and guide shaft  14  may be provided, so that the tracking is only performed in movements of working instrument  24  which exceed the play. 
     An automatic tracking of image pick-up unit  20  with respect to axial movements of working instrument  24  can be omitted if the viewing field of image pick-up unit  20  is so wide that distal end  38  of working instrument  24  is always visible when being manipulated by the operating physician. This may be considered in device  10 , for example, by the fact that working instrument  24  has, with respect to the free end of lever arm  42 , a play, so that lever arm  42  follows movements of working instrument  24  not before a predetermined intensity. 
     In the following description of other embodiments, the same reference numerals further designate the same elements as in the previous figures. 
     Guide shaft  60  in FIG. 3 differs from guide shaft  14  in the first embodiment essentially by an actuator unit  62  and a sensor unit  64  connected with same, which are arranged in a common housing  66  at the proximal end  68  of guide shaft  60 . Actuator unit  62  comprises an evaluation unit not shown in detail and an actuating drive also not shown in detail, which controls holder  21  comprising articulation mechanism  22  and, thus, the adjustment of video probe  20 . An intermittent motor is preferably used as actuating drive. 
     The sensor unit comprises in this embodiment a position sensor, which determines the relative position of working instrument  24  (here not shown) being guided in guide shaft  60  with respect to guide shaft  60 . From the obtained position, the current position of working area  36  can be deduced, so that actuator unit  62  can track video probe  20  correspondingly. 
     In FIG. 3, video probe  20  is pivoted at guide shaft  60  in a resting position, which allows to introduce guide shaft  60  together with video probe  20  through trocar  16  into abdomen  12  of the patient to be treated. As can be seen in front view according to FIG. 4, video probe  20  is located in such a position that its outer cross-sectional contour  72  is arranged essentially within and, thus, congruent to the outer cross-sectional contour of guide shaft  60 . The working position of video probe  20  of guide shaft  60  corresponds to the representation of guide shaft  14  in FIG.  1 . 
     In the representation in FIG. 4, furthermore, a guide channel  76  of guide shaft  60  can be seen, which is open on both ends, i.e. at its distal end  38  and at its proximal end  68 . In that way, it is possible to introduce different working instruments  24  into guide shaft  60  or to remove them from the same in the course of the operation. 
     With reference numerals  77  and  78 , two illumination devices are designated, which are arranged at the distal end of guide shaft  60  and at image pick-up unit  20 . Illumination device  77  comprises two LED&#39;s, which are integrated in guide shaft  60  at both sides of guide channel  76 . Illumination device  78  comprises, in comparison, a disordered fiber bundle, wherein the fiber ends are arranged concentrically to an image entrance opening  79 . Instead of the fiber bundles, however, also LED&#39;s can be arranged at image pick-up unit  20 . In the embodiment of the image pick-up unit described in connection with FIG. 1, for control and supply of the video probe and of the LED&#39;s mentioned before, furthermore, an energy source, e.g. a battery or an accumulator, can be provided in the image pick-up unit, so that the image pick-up unit works altogether autonomously. 
     In FIGS. 5 and 6, a further embodiment of a guide shaft according to the invention is designated with the reference numeral  80 . The guide shaft  80  is connected to video probe  20  via a holder  81  having a multi-axis articulation mechanism  82 . In its inner part, guide shaft  80  has a guide channel  76  open on both sides for receiving and guiding exchangeable working instruments  24 . 
     Different from the previous embodiments, articulation mechanism  82  has in this embodiment two scissor-type members  84 , between which video probe  20  is pivotably kept. As can be seen from the representation in FIG. 5, video probe  20  can also be pivoted into a resting position, in which its outer cross-sectional contour  72  is arranged within the outer cross-sectional contour  74  of guide shaft  80 . In this case, outer cross-sectional contour  72  of video probe  20  is completely congruent to the outer cross-sectional contour  74  of guide shaft  80 . 
     The functioning of guide shaft  80  corresponds to the one of the previous embodiments, wherein guide shaft  80  can be provided alternatively or complementary to each other both with a mechanically constrained coupling and with a sensor/actuator unit for tracking the video probe. 
     In FIG. 7, as a further embodiment of the invention, a guide shaft  90  is shown, which mainly corresponds to guide shaft  80  according to FIGS. 5 and 6. Different from that, video probe  20  can be separated, however, from articulation mechanism  82  and intracorporally coupled thereto. In that manner, it is possible to introduce video probe  20  and guide shaft  90  into abdomen  12  of a patient via different incisions. Video probe  20  is, in this procedure, connected with an own shaft  92  via a cable  91 . The coupling of video probe  20  with articulation mechanism  82  is preferably performed by means of electromagnets  94 , which are arranged at the outer side of video probe  20 . The tracking of video probe  20  is done in the manner described before in this embodiment. 
     In FIGS. 8 through 10, as a further embodiment of the invention, a guide shaft  100  is shown, which is similar to guide shaft  14  according to FIGS. 1 and 2. The embodiment differs, however, according to FIGS. 8 through 10, by the coupling of image pick-up unit  20  onto guide shaft  100  and the type of tracking of image pick-up unit  20  with respect to working instrument  24 . 
     Image pick-up unit  20  is fixed at guide shaft  100  via a holder  101 , which has a pivot arm  104  articulatedly fixed at intracorporal portion  102  of guide shaft  100 . Pivot arm  104  is, thus, a one-axis articulation mechanism for connection of image pick-up unit  20  with guide shaft  100 . 
     Image pick-up unit  20  immovable with respect to pivot arm  104  is arranged in such a way at the free end of the at least one pivot arm  104  that optical axis  30  runs approximately perpendicular to longitudinal axis  106  of pivot arm  104  and points at the same time to longitudinal center axis  34  of guide shaft  100  or of working instrument  24 . 
     Pivot arm  104  is pivotably connected to guide shaft  100  via an articulation  108 , wherein the pivotability of pivot arm  104  like in the holders described before in connection with the other embodiments is such that optical axis  30  can enclose an angle of at least 10°, preferably of between 20° and 70°, with longitudinal center axis  34  of guide shaft  100 , if the device is introduced into the body cavity. 
     In the working positions, image pick-up unit  20  is laterally spaced apart more than approximately 1 cm from guide shaft  100 , with pivot arm  104  having a corresponding length to this end. 
     Furthermore, pivot arm  104  can be configured in telescope-like fashion, so that the length of pivot arm  104  and, thus, the distance of image pick-up unit  20  from the articulation point at guide shaft  100 , which is formed by articulation  108 , can be enlarged, so that the angle range mentioned before and the lateral distance can be maintained. 
     Whereas for holder  101  and, thus, for image pick-up unit  20 , a mechanism comparable with FIG. 2 for tracking optical axis  30 , i.e. the viewing direction of image pick-up unit  20  to a movement of working instrument  24 , in particular an axial movement of working instrument  24 , can also be provided in the embodiment in FIG. 8, now, a particularly simple tracking mechanism will be described with reference to FIGS. 9 and 10. 
     Instead of working instrument  24  being axially freely displaceable with respect to guide shaft  100 , like shown in the embodiment in FIG. 2, and the holder having couple means in the form of lever arm  42  and of sphere  44 , which can be brought in engagement with working instrument  24 , so that, in a relative movement between working instrument  24  and guide shaft  100 , holder  101  is pivoted in order to track optical axis  30  to working area  36 , locking means  110  are provided for guide shaft  100  in order to immobilize working instrument  24  at least partially axially relative to guide shaft  100 . 
     Locking means  110  have, according to FIG. 9, at guide shaft  100 , preferably in its extracorporal portion, an annular groove  112 , in which a pin  114  runs which is provided at working instrument  24 . Pin  114  is preferably spring-loaded so that it may be disengaged by means of a suitable snap-lock mechanism not shown with annular groove  112  and can, on its own, snap into annular groove  112 . Working instrument  24  remains freely rotatable about its longitudinal axis by locking means  110  in guide shaft  100 . 
     While, by a rotation of working instrument  24  about its longitudinal axis, guide shaft  100  is, thus, not rotated, and the adjusted viewing direction of image pick-up unit  20  is, thus, not changed, guide shaft  100  is entrained into the same direction by an axial movement of working instrument  24 , and via the mechanical coupling of image pick-up unit  20  via pivot arm  104  at guide shaft  100 , same is parallely moved in the same way. In a rotation of working instrument  24  about its longitudinal axis, image pick-up unit  20  remains unchanged in its position. 
     Locking means  110  causes, thus, a complete axial fixation of working instrument  24  with respect to guide shaft  100 . 
     In comparison, in FIG. 10, a modified embodiment of locking means  110 ′ is shown, which are configured in such a way that working instrument  24  is axially displaceable relative to guide shaft  100  within predetermined limits, but entrains guide shaft  100  when the displacement exceeds the predetermined axial limits. 
     To this end, locking means  110 ′ are configured with an annular groove  112 ′ at guide shaft  100  and a pin  114 ′ at working instrument  24  in a manner comparable to FIG. 9, with pin  114 ′ being axially shorter than annular groove  112 ′. 
     Working instrument  24  can be, thus, be axially displaced over a distance relative to guide shaft  100 , which corresponds to the difference of the axial length of annular groove  112 ′ and the axial length of pin  114 ′. The limits mentioned before of the axial free mobility are, thus, determined by the front end  116  and the rear end  118  of annular groove  112 ′ and by the axial length of pin  114 ′. 
     Within this free axial mobility of working instrument  24  relative to guide shaft  100 , when working instrument  24  is displaced, guide shaft  100  is, thus, not also displaced, whereby, correspondingly, image pick-up unit  20  also is not moved and, thus, the viewing direction of optical axis  30  is maintained. The point of working instrument  24  can, thus, be moved within the predetermined limits in the unchanged image field. The limits mentioned before of the relative mobility between working instrument  24  and guide shaft  100  are, advantageously, adjusted in such a way that the range of the free axial mobility corresponds exactly to the distance between the entering in and the outgoing of the point of working instrument  24  out of the image field. Only if the point of working instrument  24  would leave the image field, guide shaft  100  and, thus, image pick-up system  20  would also be moved.