Intracorporal litotripsy procedure

TECHNICAL FIELD

The present invention relates to lithotripsy (crushing) the stones formed in the body by their fragmentation, namely to so-called intracorporeal lithotripsy, during which fragmentation is carried out using the lithotriptor working element, inside the body. The present invention provides a method of fragmentation, disintegration or degradation by any other means of stones, such as gallstones, kidney stones, bladder stones and other stones, are formed in the biliary or urinary system of a human body.

It should however be understood that the present invention is not limited to the fragmentation of concretions formed in the body. It can also be used for lithotripsy in animals.

Furthermore, the present invention is not limited to the destruction of concretions formed only in the biliary and urinary systems. It is applicable for fragmentation of any other foreign body, which can appear anywhere on the human body, such as blood vessels, etc.

BACKGROUND

During stone fragmentation method shockwave lithotripsy is used high-energy shock waves, causing the disintegration of stones and defragmentation. This method can be classified depending on how the power transmission stone into two broad groups: extracorporeal and intracorporeal lithotripsy. An overview of different ways lithotripsy can be found in a variety of sources, such as online http://www.dsci.com. In accordance with the definitions of extracorporeal shock wave lithotripsy is a process in which there is a transfer of energy required to defragment a stone in the form of a shock wave from a source outside the body through the tissues of concretions. The efficacy of extracorporeal shock wave lithotripsy (ELUV) to achieve defragmentation stones. However, due to the fact that energy transfer occurs indirectly, for the success of the treatment requires precise focusing energy on the rock, carried out through intermediate tissue. This can result in damage to tissues and therefore may require additional treatment to remove these defects.

The intracorporeal lithotripsy probe used, provided endoscopic sight and placed in close proximity to the stone. The energy required for fragmentation is transmitted through the probe to the calculus, stone crushing process visually monitored. Energy transfer may be carried out in various ways, and in accordance therewith intracorporeal lithotripsy techniques are divided into following groups: ultrasonic, laser, electro-mechanical and process / ballistic impact.

The latter group, for example, includes detonating explosives near the stone, which generates a shock wave that acts directly on the rock and smash it to pieces. An example of such a technique is described in U.S. Patent 4605003, which describes a lithotriptor comprising an inner cylinder located inside the narrow outer cylinder and having an explosive layer or a gas generating layer. Under the influence of blasting explosives or gas, or outer layer of the inner cylinder comes into collision with a stone and breaks it.

EXAMPLE method using mechanical shock can be found in U.S. Patent 5448363, which describes an endoscopic lithotriptor provided with a hammer element (a hammer), by which periodic blows on the stone. The impactor is actuated by linear pneumatic air jet, which causes it to swing in an arc about the axis and strikes the object.

There are also several other patents, which describes lithotripters, whose operation is based on a mechanical / ballistic principle, for example, US Patent 6,261,298.

An example of laser technology is described in US Patent No. 4308905, which relates to a multifunctional lithotripter equipped with a laser fiber (optical fibers) for which there is a transfer of energy needed to break the stone.

Relatively common are ultrasound techniques, which are widely used due to safety and efficacy. According to this method, an ultrasonic probe emits ultrasonic energy in the form of high-frequency waves, which have a destructive effect with direct exposure to the stone. For the effectiveness of ultrasonic lithotripsy requires direct contact probe head with a stone. This technology is used in many lithotriptors, for example the apparatus described in U.S. Patent 6,149,656.

The closest to the present invention, the technical solution is electro-technology, which uses electric discharge which occurs between two electrodes placed in the probe, and creates a shock wave that propagates towards the concrement through the liquid environment that surrounds it. In the literature, electrohydraulic lithotripsy is defined as one of the oldest methods of "electric power" lithotripsy. The electrohydraulic lithotripter produces a high-energy pulse which is generated by an electrode located on the end of a flexible probe, which is fed directly to the stone. This method is considered to be highly effective in crushing gallstones and widely used in this area. Since during electrohydraulic lithotripsy shock wave generated considerable force, the probe must not be closer than 5 mm in relation to the soft tissues, otherwise it will cause serious damage.

Due to the fact that discharge occurs in a liquid medium, the calculus is destroyed by force resulting from the combined action of the shock wave caused by the discharge, hydraulic pressure of the surrounding liquid and collision of fragments in the liquid flow. Below are some references related to devices for intracorporeal lithotripsy, which uses electro principle.

A typical electrohydraulic lithotriptor is described in patent CA 2104414. This apparatus is intended for the destruction of such deposits as biliary or urinary stones, and atherosclerotic plaques. Lithotriptor comprises a flexible elongated guide intended for oral administration, a device for supplying a working fluid, a hollow tube mounted on a distal end of the probe, a means of initiating an electrical discharge within the hollow tube from a power source located outside of which are capable of generating pulsed shock waves in the working fluid strike the stone and a nozzle made of heat resistant material and shock- and fixed to the distal end of the guide. The nozzle (nozzle) is able to direct shock waves at the focal point to strike the rock. Lithotripter is also equipped with an optical observation system (viewfinder).

U.S. Patent 2559227 discloses a device for creating a shock wave. The apparatus comprises a truncated ellipsoidal reflector for reflecting the shock waves and a cavity defining a chamber for reflecting said shock waves. The cavity has the same shape of a truncated ellipsoid, with one or two focal points of an ellipsoid disposed in the cavity opposite the truncated part. The cavity is filled with liquid, such as oil, for transmitting shock waves. The apparatus is provided with means for generating shock waves, usually consisting of two electrodes disposed at least partially within the cavity. These electrodes are designed to create an arc discharge in focus is located opposite the truncated part. The device is also provided with a device for selective and instantaneous supply voltage to the two electrodes, which leads to occurrence of arc discharge between the electrodes to form shock waves propagating through the liquid contained in the cavity. The electrodes are made of materials with high electrical conductivity such as copper or brass, and are fixed on an insulator with possibility of adjusting the distance therebetween.

Patent DE 19609019 discloses a shock tube, provided with at least one electrode located within the pilot hole. The electrode acts on the object when the probe is moved in the longitudinal direction of the object, such as stone. At the free end of the probe occurs electro-wave, causing a pressure drop.

In applying the standard electrohydraulic lithotripters no direct physical contact with the stone, and had therefore been numerous attempts to focus maximum energy emitted directly on the stone.

Efficacy electrohydraulic lithotripter stone destruction depends on voltage and duration of electrical pulses, required for achieving breakdown and initiating the spark discharge, since these parameters are interrelated with the amount of energy that can produce lithotripter.

It is easy to appreciate that due to the fact that energy is transferred to the stone, not directly but via a liquid medium, the amount of energy required to break the stone must be sufficient to exceed its durability and cause its destruction after the energy has reached the stone through the liquid (water , urine or saline). Electric pulses having duration parameters corresponding to the standard used in lithotriptor, allow to generate a significant amount of energy of about 2.5-3 J, sufficient for the formation of bumps, can destroy various types of stones formed in the body.

Unfortunately, release of an amount of energy by generating a shock wave may have a traumatic effect on the surrounding tissue and, therefore, can be hazardous to the patient.

The following well-known flaw in the technology of electrohydraulic lithotripsy methods associated with the inability to identify and trace the beginning of crushing. Because the pulse generator continues to produce pulses after the stone has already been destroyed, the excess energy is released, which is a danger to the patient.

Furthermore, another drawback of electrohydraulic lithotripsy methods associated with the necessity of forming a plurality of electrical discharges if required to destroy large stone or high density. Because the discharge occurs at the tip surface of the insulator, it causes damage to the insulation coating of the end portion of the probe and may cause its failure before the medical procedure is completed.

Another problem of almost all intracorporeal lithotripsy techniques by destroying kidney stones by transmitting mechanical energy of impact or shock wave is the fact that with each pulse stone "shifted" from the old place and "thrown" to the other. This complicates the operation and can cause mechanical damage to the surrounding tissue. In this case, it would be very desirable physical "capture" of processed stone.

An attempt to solve the aforementioned problems of increasing the effectiveness of treatment without the risk of harming the patient is considered in patent DE 3927260. This patent discloses a method for breaking rock using electrohydraulic lithotripsy probe provided with a head made of impact-resistant ceramic material and having the shape of a rounded rod. The rod has two longitudinal channels into which are immersed and fixed by means of polymeric material wire whose ends are flush with the end face of the rod. Wires coming to a fork in a flexible sleeve, which passes through the head.

Nevertheless, this particular solution is not to create a direct physical contact between the stone and the final section of the probe, generating a shock wave.

Known methods for the destruction of stones by means of "capture" and subsequent processing, for example through the combined device for gripping and lithotripter stone described in the patent DE 19810696. Said composite device consists of a highly NiTi (nickel-titanium) alloy and provided with at least three manipulators are curved in an expanded state in the form of a tulip. The end section of each arm is provided with teeth and is folded in the direction of the tool axis. When the handles are drawn into the tube device or operating channel, they are placed on a stone and seize it as their further retraction. The holding device is located on the axis of the tool so that the angle between adjacent manipulators never exceeds 180 °. This ensures reliable gripping and retention and thus prevents slipping of the captured stone. Securely attached stone can be completely destroyed by fragments of predetermined dimensions using a lithotripter, ie mechanically-ballistic method, ultrasound, cryogenically or thermally with laser.

Unfortunately, this method is not suitable for use in electro-hydraulic mode, as the probe head does not provide for the supply of its electrodes with the insulating coating and are therefore not capable of producing shock waves, caused by electrical discharge.

On the other hand, has for some time a method is known so-called high-power electro-impulse destruction of materials, based on the fact that by applying electrical pulses with a period of increase of not more than 500 nanoseconds to electrodes located on the solid material immersed in water is generated discharge which does not extend through the surrounding liquid medium, but is passed through the bulk of the solid. This technology was developed in Russia in the late fifties and has since been successfully applied for the destruction of solid rock and ore mining, destruction of concrete blocks in the building industry, drilling frozen ground and highly sawmills, destruction of various inorganic materials, etc. .

Review this technology can be found in the book "Fundamentals of electro material destruction" Semkin and colleagues, St. Petersburg, Nauka, 1993.

According to this technology two or more electrodes are placed directly on the surface of a solid body (rock) and send them via the very short pulses with a voltage U (t). Once initiated between the electrodes of an electrical breakdown, it occurs in the bulk solid and leads to a discharge channel that extends within the solid body. The body serves as a medium for the spread of electric breakdown to a much greater extent than the environment. Distribution of the discharge channel through solid accompanied by the creation of mechanical stresses, which stretched above the body and destroy it as soon as exceeded the tensile strength. In fact, in the process of destruction of electro-initiation and spread of discharge similar to microexplosions what is happening inside the body. It is easy to appreciate that as the tensile strength of the stone, at least an order of magnitude less than its compressive strength, electropulse destruction associated with the expenditure of much less energy, than conventional electro-hydraulic destruction.

It was also found empirically that the probability of propagation of the discharge channel through the material is higher when a very short voltage pulses applied to electrodes placed on a solid body immersed in a liquid medium, since the voltage necessary for the occurrence of discharge in the mass of the solid body is less than the voltage required for the occurrence of discharge in the liquid medium surrounding the body.

Unfortunately, despite the fact that this technology exists for more than 40 years, it is still mainly used in the coal industry, and building industry for destruction of very large objects like rocks or concrete blocks.

An example of such use can be found in WO 9710058, which describes a method of crushing and breaking of solids, for example blocks of reinforced concrete. In accordance with this method, the solid blown by creating shock waves therein.

Unfortunately, the obvious advantages of this technology, associated with more efficient destruction, have never been used in a completely new aspect, as medicine and, in particular intracorporeal lithotripsy.

In conclusion, it must be emphasized that, despite the fact that it was already developed many different types of lithotripters, there is still a need for a new approach that would guarantee an effective, reliable, easy and safe fragmentation of stones in intracorporeal lithotripsy.

SUMMARY OF THE INVENTION

The main object of the present invention is to provide such an improved method for intracorporeal lithotripsy, which would allow to significantly reduce or overcome the above drawbacks of the known solutions.

In particular, one object of the invention is to provide such an improved method for intracorporeal lithotripsy, which would ensure the application of tensile stress instead of a compressive stress stones forming in vivo.

Furthermore, another object of the invention is to provide such an improved method for intracorporeal lithotripsy, which would allow to reduce the likelihood of traumatizing of adjacent body tissues during the treatment.

Another object of the invention to provide an improved method of performing intracorporeal lithotripsy, which would allow to determine the start of the fracture process and terminate further generation of high voltage pulses.

Furthermore, the present invention is to provide an improved method for intracorporeal lithotripsy, which would provide an easy and rapid destruction and simultaneous capture and hold the stone to be fragmented during the procedure.

The above and other objects and advantages of the present invention can be achieved by the following combination of its essential features, referring to different embodiments of the disclosed method for intracorporeal lithotripsy.

The present invention may be implemented as a method, which provides for settlement of the probe to the stone to be destroyed, said probe is provided with electrodes connected to the means for generating high voltage pulses, said pulses supplied to the electrodes to generate a spark discharge between them and release of energy, causes destruction of the stone, said method comprising the step of driving at least one electrode in direct electrical contact with the stone, so as to form a discharge channel capable to create shock waves and stresses that exceed the strength of the stone material.

The present invention may be implemented using a device which comprises:

- Means for generating high-voltage pulses needed to create a spark discharge and generate enough energy to destroy the stone;

- A probe for insertion within the body and energy transmission stone comprising the sheath with electrodes, arranged inside said shell and having respective distal and proximal ends, said proximal ends of said electrodes are connected to the means for generating the pulse, and the distal end of the at least one electrode adapted be brought into direct electrical contact with a rock;

- Handling means for controlling the probe sheath with electrodes inside the body and bringing at least one electrode in direct electrical contact with the stone.

Here is a brief description of the invention and its two basic design options. For a better understanding of the present invention and its embodiments and advantages, a detailed description with reference to the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

1 schematically shows the formation of a spark discharge in the electro-hydraulic and electric pulse lithotripter.

2 is a block diagram of an apparatus for electro-impulse lithotripsy according to the present invention.

3 shows an example of a pulse generator, which is used in the lithotriptor of the present invention.

Figure 4 shows another embodiment of the pulse generator, which is used in the present invention lithotripter.

4B is a more detailed schematic of the pulse generator shown in Figure 4a.

5 shows a control circuit used in conjunction with the pulse generator shown in Figure 4b.

6a-6c schematically illustrate the principle of electro-hydraulic and electro-lithotripsy.

7-10 refer to various embodiments of the probe, which is used in the method according to the present invention.

Detailed description of specific examples of the present invention

Consider the principle of operation of electro-hydraulic and electro-impulse destruction of the example circuit shown in Figure 1.

The source of high voltage pulses 110 delivers pulses through the switching device 120 in the platform 130, filled with hydraulic fluid, where the electrodes are placed between the electrodes 140. Emerged electrical discharge used for the destruction of the object 150 located in the workspace. Although not shown in the diagram, but it should be understood that the object implies a stone to be destroyed, and the working area is a body cavity, where the said stone surrounded by a liquid, such as a gallstone, formed in the gall bladder, stones in the urinary system etc.

The figure on the left (a) illustrates an electro-destruction method; wherein due to the fact that the electrodes are not in direct contact with the object, failure occurs mainly due to shock waves - SW (shock waves), caused by the spark discharge and transmitted through the working fluid object.

The figure to the right (b) illustrates the electric pulse method of destruction; wherein electrodes are placed directly on the surface of the object, so that a spark discharge occurs within the object. This solution spark high power generates a spark channel within the object itself. Through the release impulse energy within the spark channel the pressure within the channel dramatically increases its diameter increases, causing tensile stresses within the object. Due to these tensile stresses in combination with hydraulic pressure of the surrounding liquid medium and collisions fragments object takes its effective fragmentation and degradation. The present invention relates to an intracorporeal lithotripsy carried out based on the principle of electro-impulse.

It is found that the probability of propagation of the spark channel through the bulk of the object increases with an increase in the energy release rate inside the object. This means in particular that it was preferable to apply high voltage pulses with a very short rise time and duration. In practice it has been found that for the destruction of a wide spectrum of stones formed in the living body and be intracorporeal lithotripsy, is preferably supplied to the electrodes of pulses, characterized by the following parameters: rise time tf less than 50 nanoseconds, preferably less than 40 nanoseconds, duration of the actual pulse ti max 5000 nanoseconds, preferably 500-3000 ns, pulse energy W0 = 0.1-1.0 J, the pulse amplitude U = 5-20 kV. The preferred configuration of the pulse - rectangular.

The pulses may be supplied either as a single pulse or a repetitive pulse with a frequency of several Hz.

Furthermore, it was empirically found that by supplying electrical pulses, characterized by the aforementioned parameters, it is possible to destroy the stone, having electrical strength exceeding the pulse amplitude, since the electrical breakdown threshold for repetitive pulses below the threshold electric breakdown during simultaneous pulsing. At the same time the energy spent on the destruction of stone, much less than the total energy pulse is applied, since all pulses except the last, due to the partial discharge.

In actual use, it is preferably supplied to the electrodes high voltage impulses with positive polarity, since this is associated with increased likelihood of breakdown.

It has been found that the application of the present invention, even when using one or more pulses may effectively destroy various stones. It is easy to calculate that the level of energy associated with the applied pulse, about two, three and more times lower than for standard devices electrohydraulic lithotripsy, which is an additional advantage of the present invention.

Figure 2 schematically illustrates an apparatus 200 for performing the method intracorporeal electro-impulse lithotripsy according to the present invention. The apparatus comprises a pulse generator 201 coupled to the probe 203 and probe control means during his stay in the patient.

Driving pulse generator includes the following main blocks: the charger 210, energy storage means (eg, a capacitor) 220, switching means 230, a pulse generating circuit 240 and the control circuit 250. As a suitable charger, you can use a constant voltage source or a pulsed power source. As suitable switching means can be used conventionally used in the art spark gaps and control switches, such as transistors, thyristors, tirotrony and other electronic switches. The specific design of the pulse generator can vary. For example, according to one of designs generator shown in Figure 3 and designated by reference numeral 300, includes a transmission line 310 made ​​of coaxial cable and having a fixed length, wave resistance Z and capacity Cp electricity. Power of the line is carried out from the power supply 320 to provide voltage reaching U0, which allows you to create a positive surge voltage, followed by discharge of the voltage across the switching means 330 to the load 340 has a resistance RH, such as stone. The hallmark of this constructive embodiment is that the beginning of one of the conductors comprising a cable connected to its tip and thus, by closing the switching means a certain kind of wave is formed simultaneously at both ends of the cable.

Since the line at one end of a load resistor 360 has activity equal to the characteristic impedance (Rc = Z), at this end of the reflected waves do not arise, and the load 340 irrespective of its resistance RH, repeated pulses are not transmitted. The pulse duration in the load is equal to the time of wave propagation from one end of the line to another. The amplitude of the voltage and current for the generator is determined by the following relationships:

U = U0RL (Z + RL) I = U0 / (Z + RL),

where RL = Z, U = 0,5 I = U0 / 2Z.

In this embodiment variant pulse energy, which will be released on the load RH, two times lower than the stored energy as load resistance RC consumes half the energy.

If RL << Z, the pulse amplitude of the load voltage approaches the value U0 (power supply voltage).

In practice, use a coaxial cable with a characteristic impedance of 50 ohms, the specific capacitance of 0.1 nF / m and the speed of propagation of the wave 5 ms / m. With a cable length of 50 m length of the load pulse is about 250 ns at capacity Cp = 5 nF. The amount of accumulated energy, defined as W = CPU2 / 2 ranges from 0.25 to 1 joule in accordance with the voltage variation from 10 to 20 kV.

Pulse rise time of the load depends on the parameters of the switching means. In practice it was about 15 nanoseconds. It was also found that if the RC >> Z, can be achieved with a flat top pulse (plateau) of duration equal to tenths of a microsecond. The pulse thus is complete breakdown (short circuit) on RL and decays exponentially with a time constant τ = CPRL, if the sample does not occur.

Further, in Figure 4, showing another embodiment of a pulse generator for implementing the method according to the invention. In this arrangement, the pulse generator 400 is designed as a "concentration capacity." As in the previous embodiment, the pulse generator connected to a probe 420, which is controlled by means of control probe 410.

In this arrangement, the pulse generator circuit includes a charger 430 connected in parallel with the first capacitor 440, which in turn is connected through unregulated switching means 450 of the dividing inductance 460, secondary tanks 470, 471, 472, 473 and a transformer, consisting of the induction coils 480, 481, 482, 483 wound around common ferrite core (not shown). The scheme also includes adjustable switching means 451, a pair of current sensors 490, 491 and a control circuit 495, equipped with a pulse counter, pulse generation mode indicator and mode indicator breakdown.

Sensor 490 is placed on the first winding of the transformer and for counting the total number of voltage pulses, generated during the procedure. The sensor 491 is located on the second side of the transformer and is designed to determine the occurrence of breakdown between the electrodes and the formation of a spark channel. Both sensors are connected to the control circuit, which controls operation of chargers and disables them as soon as a predetermined number of pulses is reached, or the breakdown occurred, depending on what happens first.

Next, with reference to Figure 4b, a more detail diagram of an embodiment of the invention, using "lumped capacitance."

The circuit indicated by reference numeral 500 and comprises a group of primary containers C1 and C2; separating inductive coil L1; two bit device P1 (unregulated) and P2 (adjustable), a group of secondary containers C3-C6; a pulse transformer T3; elements R7, C7, RE, constituting the discharge control circuit to the device F2, and inductive sensors T4, T5, connected in parallel with respective resistors R9, R8.

Sensor T4 detects pulses in the first winding of the pulse transformer T3, i.e. all the pulses supplied to the object. Sensor T5 detects pulses in the output (discharge) the pulse transformer T3. The sensor is configured to determine the pulse, causing the breakdown of the passage through the object. It also provides specialized chip, which will be discussed later, the transmission signal corresponding to each pulse to pulse counter (not shown) for counting the number of generated pulses. In practice, as the pulse encoder can be used Rogowski coil (Rogovski coil) or any other suitable type of sensor.

The high-voltage rectifier charges the capacitors using the primary circuit of the transformer T2 and diodes VD1, VD2, shunted resistors R1-R4. Resistors limit the pulse currents passing through the transistors when there is a discharge of capacitors C1, C2.

As soon as the voltage across the capacitor reaches a value sufficient for the occurrence of the breakdown in the discharge device P1, it is charging the capacitor through the secondary inductive coil L1. Each of the capacitors C3-C6 discharges on the first winding of the pulse transformer T3 after the discharge device worked P1 and P2.

The amplitude and frequency of the pulses depends on the position of the control switch S2 and on the embodiment of the discharge devices P1 and P2.

Further circuit comprises a control circuit 510, which is equipped with, among other things, the relay K1 and light indicators VD3, VD4, and VD5, denote the "Network", "Discharge" and "Breakdown."

The control circuit is connected to a pedal switch S3 for remote switching pulse generator from the "discharge" to "Stop". The control circuit is connected via a transformer T1 and a switch S1 to a network having a voltage of 220 V and 50 Hz.

The generator connected to the grid through the relay K1, which is controlled by a remote pedal switch S3. At the moment when the generator warning light illuminates and shows VD4 mode "Discharge".

5 shows a control circuit 510 that contains, among other things, a pulse counter, consisting of microcircuits DA1, DA2, transistors VT1 and VT2, and chips DD1, which compares the actual number of generated pulses with a predetermined value. Before turning on the pulse counter is put up for the required number of working pulses from 1 to 99.

After switching pulses generated by the generator fixed sensors T4, whereupon transistor VT2 passes the signals associated with those pulses to the pulse counter. Once the number of generated pulses reaches a predetermined value, the chip DD1 closes the transistor VT1 generator automatically turns off. Further work of the generator is possible only after pressing and release the foot switch S3.

Once breakdown occurs and the spark channel is formed, the generation of pulses stops and indicator lights VD5 to alert about this event. In this situation the pedal switch should be released to stop the generator. Inspect the stone in order to determine further treatment. If the observation found that the stone requires further destruction, the generator includes repeated by pressing once and release the foot switch, each time accompanied by the observation of the stone.

The above pulse generator is capable to generate pulses with duration of about 100 nanoseconds, and the pulse rise time is about 50 nanoseconds, and the pulse amplitude is 10 to 20 kV.

Since the above described control circuit allows limiting the number of pulses, which are potentially harmful to the patient, it is obvious that the procedure becomes more safe and at the same time robust.

In the above-described oscillator is applied energy storage means, which comprise the capacitive reactance. It should be understood, however, that it is possible to use alternative means of storage, for example on the basis of induction devices.

According to the present invention may be various kinds of electric contact between the electrodes and the object.

Figure 6 schematically shows the different forms of spark discharge propagation depending on the location of electrodes relative to the object to be destroyed. 6 is a diagram which relates to the standard electro degradation and comprises a high voltage central electrode 610 surrounded by a second annular electrode 620, having a tube shape, concentric with respect to the first electrode. The diagram shows that the object 630, such as a stone, is spaced from both electrodes and due to the presence of the gap 640 none of the electrodes is not in direct electrical contact with the stone. The shock waves of 650 resulting from the spark discharge 660 propagate toward the stone. The stone with the discharge channel is not formed.

6b shows that both electrodes are in direct electrical contact with a rock and stone, and between them there is no gap. The discharge channel 660 is formed between the electrodes inside the object and causes its destruction due to the formation of many small cracks 670.

6C shows that in direct electrical contact with the object is just one electrode, while the central electrode is spaced. However, while the discharge channel is formed inside the mass of the object which causes its destruction.

7a-d shows a probe for electro-impulse lithotripsy, which allows to establish direct electrical contact with the object to be fragmented, as shown in Figure 6b.

The first example of the invention, indicated by reference numeral 700. In this embodiment the probe itself comprises a tubular sheath 710, through which extends a high voltage central electrode 711 with the insulating coating 712. Preferably the sheath 710 is made of a dielectric material, although alternatively it can also be made of a conductive material provided insulation coating. There is also a second electrode 713. This electrode comprises a tubular part that is placed inside the casing coaxially and concentrically with respect to the central electrode.

The distal end of the second electrode is provided with a pair of elastic contacts 714, isolated insulation coating 715. Both electrodes are placed inside the shell with the possibility of independent linear displacement along the longitudinal axis of the probe from the extreme positions offset backward (retracted state) in which the electrodes are completely inside the shell, in the limit position forward bias at which the electrodes are outside the sheath. In the extended position of the electrodes can be close to the outer surface of the stone to be degradation and then from the pulse generator is supplied to the electrodes high voltage impulses.

The diagram is not shown in detail, but it is understood that the proximal ends of the electrodes are operatively connected with the means of carrying out a linear displacement of the electrodes, wherein said device is indicated in Figure 2, 4a as a control probe 202 and 410 respectively. It is understood that the biasing means may comprise any suitable apparatus normally used for controlling a lithotriptor probe.

Next in Figure 7a is not shown in detail, one of the electrodes is electrically connected to the pulse generator to receive high voltage impulses with the above parameters and the second electrode is grounded.

7a shows the situation when both electrodes are located within the shell in the retracted position and almost ready for exit.

In Figure 7b it shows that the second electrode is provided in an extreme extended position, wherein the resilient contacts 714 are connected to the stone 716 and are located with it in direct electrical contact. Wherein the central electrode is still within the sheath and ready for advancement towards the stone to establish electrical contact with it.

According to the present invention, the number and specific shape of elastic contacts might be different. In practice the contacts are made of biologically inert, elastic and electrically conductive material such as TiNi, or any other suitable material, including so called memory alloys form (temperature-dependent carrier effect). The insulation coating completely covers the contact, except for their front end, which will have to be in contact with the stone.

According to another embodiment of the invention, in the embodiment shown in Figure 7, the contacts have a controlled capture rectilinear shape, wherein the ends are bent at an acute angle relative to the longitudinal axis of the probe. This creates the opportunity to better capture and hold the stone and at the same time ensuring better contact with its surface.

7C shows an alternative constructive embodiment of a probe in which the sheath is made of electrically conductive material and the second electrode is covered by an insulation coating 717. The distal end of the second electrode is provided with a pair of elastic contacts 718 of the arcuate shape.

7D shows another embodiment in which the elastic contact with the second electrode are provided with holding basket 719, which serves for immobilization of the stone and its retention during the procedure. An example of such a basket is described in our previous patent application PCT / IL01 / 00591, the disclosure of which is fully included in the description of this application by reference.

Another embodiment of the probe shown in Figure 7. In this embodiment the sheath is made of metal and instead of two concentric electrodes using a symmetrical two-core cable 720, disposed inside the shell with the possibility of linear displacement along the sheath. The cable has two conductors 721, 722, the proximal ends of which are electrically connected to a pulse generator (not shown). The distal ends of the electrodes are connected, for example soldered, to elastic contacts 723, for example similar to those described above. 7A, f respectively show the probe provided with a two-core wire at the time of displacement forward and back.

On 7G shows a further design of the present invention, where the supply of pulses instead of a two-wire balanced cable using two separate insulated wires. The two wires may be twisted together or may be arranged parallel to each other. As in the previous embodiment, to the distal ends of both wires are attached elastic contacts, the shape of which is suitable to capture the stone and establishing immediate electrical contact therewith. In practice the electro-impulse lithotriptor used in combination with an endoscope, equipped with suitable optics enabling monitoring the procedure produced in a living organism. The endoscope is introduced into the front of the introduction of the probe, and is fed directly to the stone. Then the stone is supplied probe. Once the probe occupies a desired position by means of a pushing device bias electrodes to achieve a contact with the stone. If the probe consists of two concentric electrodes, first it moves forward a second electrode provided with resilient contacts and only after that - the central electrode. Once the stone is captured contacts switched pulse generator and the electrodes are fed voltage pulses with the above parameters for the initiation of the spark discharge, resulting in the stone mass passes through the discharge channel, which leads to the destruction of the stone.

8a-c show further variants of embodiment of the probe. These design options are adapted for establishing electrical contact with the object according to the method shown in Figure 6c.

As in the previous embodiment, the probe 800 is provided with a high voltage central electrode 810, extending along the probe and having a coating of an insulating tube (sheath) 811 made of a dielectric material, e.g. TEFLON, FEP or RTEE, or any other suitable material, mechanically resistant shock wave arising in the course of the procedure.

The front end of the center electrode is exposed so as to allow an electrical contact with the object to be destroyed (not shown) immediately after the lead electrode in physical contact with the latter. The second electrode 812 has a cylindrical shape and is placed concentrically with respect to the central electrode. The second electrode has outside an insulating cover 813 is also made of a dielectric. Unlike previous versions of design the second electrode is not provided with the electrodes with an adjustable gripper, a basket or any other means of ensuring the seizure and retention of the object. Instead, the front end of the second electrode is attached a washer (ring) 814 made of a conductive material. To a proximal end attached to the probe tip having a bowl portion 815 facing forward, and a conical rear portion 816. The inner diameter of the front portion is larger than the outer diameter of the probe, so therebetween an annular space is formed. In the annular space located short sleeve 817, made of an electrically conductive material and provides the possibility of establishing electrical contact with the second electrode through said washer. The length of the sleeve and the back of the tip are selected so that the end of the center electrode and the end of the bushing lie in the same plane P and form a working electrode. In practice, it is necessary that the length of contact between the sleeve disposed within the tip and the probe is 4-6 mm. Once the probe is brought to the object and working electrodes are brought into contact with it, electrical connection is established according to the mode illustrated in Figure 6b or 6c. Obviously, due to Embodiment shown in Figure 8, can localize the spark channel at the very end of the probe and hence make it possible to spread either on the surface of the object, or through its bulk, thus providing much more efficient destruction than during normal electrohydraulic lithotripsy. 8b shows another constructive version of the probe, according to which the auxiliary contact 818 made of elastic heat resistant (refractory) material fastened to the front end of the center electrode. Examples of suitable materials for the auxiliary contacts may be TiNi, stainless steel etc. Due to the possibility of extending said contact spark channel within the object increases, which in turn extends the life of the probe.

Another embodiment of the invention shown in 9a, b, c. According to this Embodiment is provided with a probe contact element made of electrically conductive superelastic material (e.g., stainless steel) or a shape memory alloy (e.g. NiTi).

The probe consists of a central electrode 901 electrically insulated from the second electrode 903 and coating 902 disposed parallel to the central electrode. By the end of the second electrode, capable displaceable along the probe is attached a loop-like contact element 904, made of a thin strip or thread. This contact element may include stone, whereas the second electrode is in the forward position shown in Figure 9b. The central electrode is also arranged slidably along the probe and once it comes in contact with the rock 905 the contact element starts bending around the stone, as shown in 9c, which ensures reliable contact with the last loop. Flexing or possible due to the elasticity of the hinges, or during manufacture of the alloy with shape memory, when it is applied to a weak voltage.

Examples of probe constructed in accordance with this constructive embodiment, shown in Figure 10a, b.

Thanks to the method according to the present invention can more effectively destroy various kinds of concretions formed in the body by applying energy, which is several times less, than in conventional electro hydraulic lithotripsy. It becomes possible as a result of degradation due to the rupture stress, caused by propagation of the spark channel, passing over the surface or through the bulk of the concrement.

Furthermore, as destruction can be carried out selectively, by supplying a predetermined amount of impulses instead of plurality of high frequency pulses, the procedure safer for the patient and the possibility of traumatizing the adjacent tissues is worse.

Another advantage is that the number of high voltage pulses needed for the occurrence of electrical breakdown between the electrodes may be set beforehand, and consequently the electrodes are worn less, and the probe lifetime increases accordingly.

The probe design is simple and at the same time secure. It allows you to capture and hold the stones during the procedure, which also contributes to the reliability of the treatment.

It should be understood that the present invention is not limited to the above described examples and embodiments. Any person competent in the art may make variations and modifications without departing from the scope of the invention. For example, as a sensor for detecting the generated pulses can use inductive or capacitive sensor, instead of a current sensor to determine the onset of breakdown can use inductive, capacitive or resistive sensor, etc.

Description referring to Figure 4b, does not disclose details of the private parts of different images on its components, such as diodes, resistors, integrated circuits, since the choice of these items refers to the standard transactions usually require skills in this area.

Note also that all of the features listed in the above description and / or the following claims and / or in the accompanying drawings (circuits) in combination or taken singly, are essential for realizing the invention in various embodiments.