Abstract:
A muscular tissue revascularizing apparatus. First electrodes generate a heat effect into the muscular tissue. Second electrodes generate pulsed spark discharge shockwaves into the muscular tissue.

Description:
BACKGROUND OF THE INVENTION 
     The invention concerns a device for revascularizing muscular tissue by producing a tubular necrosis. 
     Such devices are known and are finding increasing clinical application, in particular in the field of cardiac surgery. 
     In the category of “transmyocardial laser revascularization”, such as laser myocardial revascularization (LMR), predominantly three different laser systems, i.e., pulsed CO 2  laser, pulsed holmium-YAG laser, and pulsed excimer laser are currently used, primarily devices from the US companies PLC, CARDIO GENESIS, and United States Surgical Corporation. With these pulsed laser. systems, it is possible, through the use of the mechanism of so-called photoablation, to create transmyocardial channels; and, based on the system, thermally affected marginal zones and also shock waves are produced through the process of photoablation. These systems are extremely expensive, and, even so, amplitude and depth of effect of the shock waves cannot be optimized. 
     SUMMARY OF THE INVENTION 
     The object of the invention is, consequently, to provide a comparatively simple and economical device for revascularizing muscular tissue, in particular heart muscular tissues, which offers improved possibilities for optimization of the treatment parameters. 
     The invention includes the technical teaching of providing a device with which, independently of one another, the wall of a tubular necrosis or of the channel generated in the course of revascularization can be deliberately affected thermally and with which shock wave-like pressure amplitudes with separately adjustable parameters can at the same time be generated in the vicinity of the wall. 
     It also includes the idea of using different energy sources to produce the thermal effects on the one hand and the shock wave effects on the other, in the interest of separate control of the parameters. According to investigations by the inventor, the combined use of HF energy and electrical pulses with relatively high field intensities of an electrical shock wave generator is particularly economical and presents advantageous effects. The HF energy is expediently in the range of a few watts and the pulse field intensity is a few kV/cm. 
     Surprisingly, it turned out that the use of bifilar, helically wound high frequency electrodes, which are mounted mutually isolated on an puncture needle, causes shrinkage of this tissue upon input of the high frequency energies and distribution in the parietal tissue. After removal of the puncture needle, an open channel remains. At the same time, by deliberate variation of the high frequency energy, the heat introduced into the channel wall can be deliberately varied with a view to the expansion and consistency of the remaining tissue. Similar effects were also obtained with other HF electrode configurations. 
     By the additional installation of two mutually isolated high-voltage electrodes, which can lie exposed on the end or along the HF application system (the HF puncture needle), it is also possible to produce a spark-like puncture by the brief application of zero-potential high voltage, which in turn produces shock waves in the vicinity. 
     By variation of the high voltage in the duration of the high-voltage pulse, it is possible—independently of the introduction of thermally active HF energy via the bipolar HF electrodes—to separately vary the strength of the shock wave amplitudes. Through selection of different bipolar electrode configurations, it is possible to control the thermal coagulation zone. 
     In a preferred exemplary embodiment, the HF puncture needle is made of a break-resistant ceramic metal composite capillary, on whose outside wall the bipolar HF electrodes are installed and in whose interior the leads of the HP electrodes are guided mutually isolated and attached on the edges of the distal end. However, other suitable materials, such as high temperature resistant plastics (PBEK, PPSU, etc.), may also be used as electrode carriers. 
     According to a preferred exemplary embodiment, the HF puncture needle is exchangeably mounted in an electrically, mechanically, or hydraulically driven advancing device located in the interior of a hand piece. The hand piece itself is advantageously designed with a distal attachment holder such that during use of the device for perforation of the heart muscle, anchoring in the epicardium is possible and the puncture needle can be inserted under control into the heart muscle by means of the advancing device. 
     Energy is supplied to the HF electrodes by a bipolar high frequency generator with adjustable output and appropriately adapted terminating impedance; the high-voltage pulse electrodes are supplied by a high-voltage pulse generator. 
     In further development of the idea according to the invention, to produce larger channel diameters, a rotating hollow knife by which the contour of the channel is cut into the tissue can be provided instead of the puncture needle. The addition of a suction pump on the above-described hand piece makes it possible to aspirate the excess tissue in the interior of the hollow knife. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Advantageous improvements of the invention are presented in detail within the framework of the description of the preferred embodiments of the invention with reference to the figures which depict: 
     FIG. 1 a device according to one exemplary embodiment of the invention depicted in longitudinal cross-section, 
     FIGS. 2 a-   2   c  additional embodiments in side views, 
     FIG. 3 a cross-sectional depiction of the hollow point of the device according to FIG. 1, and 
     FIG. 4 a side view of another embodiment. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 depicts, as an example for a device according to the invention, an application system  1  with an instrument or hand piece  2 , an electrical drive unit  3  accommodated therein, and an HF assembly  4 , which can be displaced linearly in the axial direction by means of the drive unit  3  against a zone of body tissue T. 
     Distally coupled to the HF assembly  4  is an applicator, the bipolar puncture needle  10 , which can output both the electrical energy generated by a controllable HF generator  5  and that from a controllable high-voltage pulse generator (shock wave generator)  6  to surrounding tissue (not shown). The electrical connection of the HF assembly  4  with the puncture needle  10  to the voltage generators  5 ,  6  takes place via flexible leads  7 . A process control unit  8  is provided to actuate the drive  3  as well as the voltage generators  5 ,  6  as a function of the EKG signals ECG reflecting heart movements. 
     Through a laterally open area  9   a , a positioning plate  9  provided on the distal end of the hand piece  2  with a tissue holding arrangement enables precise visually supported positioning of the applicator  10  in the operating field. 
     For a revascularizing treatment of the heart, the hand piece  2  is placed with the positioning plate  9  on a selected epicardial zone and—after preselection of the treatment parameters, such as HF power, pulse amplitude, and pulse repetition frequency as well as advancing speed, etc.—in synchronization with the heart activity by means of the process control  8  and the drive  3 , the puncture needle  10  is pushed into the tissue, and simultaneously HF power as well as a voltage pulse is introduced into the tissue and then the puncture needle is again withdrawn. 
     FIG. 2 a  through  2   c  depict different embodiments of HF applicators (puncture needles)  10 ,  20 , and  30 , respectively, which are used in an overall structure which corresponds fundamentally to the structure depicted in FIG.  1  and described above. 
     The applicator  10  in FIG. 2 a  has two electrodes  11 ,  12  of equal length and equal diameter separated by an isolating zone  13  arranged one behind the other in the direction of the longitudinal axis on the distal end, there is a hollow point  14  with lateral openings  14   a  Pulse electrodes are arranged inside this point (see FIG.  3 ). 
     The applicator  20  according to FIG. 2 b  has two bifilar electrodes  21 ,  22  wrapped on the basic body  23 , which are at different potential during use. A hollow point  24  on the distal end has the same structure as described above with regard to FIG. 2 a.    
     The applicator  30  in FIG. 2 c  has two electrodes  31 ,  33  [sic  32 ] extending in axial direction arranged in parallel on a dielectric basic body  33 . This applicator  30  also has a hollow point  34  on the distal end, as described above. 
     FIG. 3 depicts a cross-section of the transition zone between the cylindrical section and the hollow point of the HF applicators along the cutting plane A—A. 
     There, four pulse electrodes  15  are arranged spaced such that a pulsed arc discharge L can develop between them, the energy of which passes through the openings  14   a  of the point  14  into the surrounding tissue T in which a channel C is formed by means of the applicator and produces a shock wave. 
     FIG. 4 depicts as another embodiment an applicator  40 , wherein the I-IF electrodes  41 ,  42  are arranged on the carrier body  43  as in the embodiment according to FIG. 2c, where the pulse electrodes  45  are not arranged in a hollow end, but rather are arranged galvanically isolated on the applicator jacket surface in its cylindrical zone. The point  44  is manufactured as a solid from biocompatible plastic. 
     The invention is not restricted in its embodiment to the above-reported preferred exemplary embodiments. Rather, a number of variants which make use of the solution presented in differently designed embodiments is possible. 
     Thus, a simplified embodiment has a manual process controller of the puncture needle advancement and the application of the HF and pulse voltage via a pushbutton on the hand piece. Satisfactory results can also be obtained with this embodiment on the quiescent heart.