Device For Destroying Stones In The Bladder, In The Ureter, In The Kidneys And The Like

Abstract

A device for destroying stones in the bladder, in the ureter, in the kidneys and the like, comprising an elongated, flexible lithotriptor insertable in conjunction with a cystoscope or a special catheter through the urethra into the interior of the body until such time when it comes into contact with the stone to be destroyed, a driving mechanism comprising a chamber filled with a liquid, a membrane closing the chamber and rigidly connected to the lithotriptor, and imparting longitudinal mechanical vibrations to same two electrodes inserted in the chamber in such a manner as to provide electrical insulation, and a means which makes electric flashovers between the electrodes possible inside the chamber.

Description

The present invention relates to a device for destroying stones in the bladder, in the ureter, in the kidneys and the like, comprising an elongated flexible lithotriptor insertable in conjunction with a cystoscope or a special catheter through the urethra into the interior of the body until such time when it comes into contact with the stone to be destroyed, and connected with a driving mechanism by means of which longitudinal mechanical vibrations are imparted to the lithotriptor.

Conventional lithotriptors serve for the destruction of stones in the urinary bladder exclusively. Such destruction was formerly achieved either blindfold or with the use of endoscopes by purely mechanical means. As a result, more or less serious lesions of the mucuous membrane, haemorrhages and occasionally even perforations did occur in the process.

Some improvement has been achieved after the so-called electro-hydraulical lithotriptic method had become known. This method takes advantage of the effect of hydraulic shock waves produced by electric charges in a liquid dielectric medium. The lithotriptor presents a probe comprising an insulated central and a cylindrical external electrode or, in accordance with a recently devised variety of design, two highly insulated electrodes arranged side by side. However, this method is somewhat inconvenient inasmuch as the diameter of the lithotriptor used for that purpose cannot be less than 8 charr., and electric currents of as much as several thousand volts and several hundred amperes have to be sent through the ureter as far as close to the stone. During the flashover, lesions of the mucuous membrane are liable to occur and when a predetermined minimum distance is not attained, perforation may result from coagulation of the bladder wall. Another drawback of this method resides in the fact that it takes advantage of the hydraulic wave produced by an electric discharge and can therefore, be resorted to only provided there is a liquid between the stone and the lithotriptor and a certain volume of liquid is available in the area of the discharge. In view of the necessity of accommodating two highly insulated electrodes, a liquid current as well as lighting conduits and optical devices inside a common shaft, it is not possible with the technology at present available, to employ this method in the urethra.

Another method which has been tried time and time again, and which recently turned out to be partly successful, is called the supersonic lithotriptic method. The sound energy is supplied by a magnetostrictive or piezoelectric transducer connected to a high-frequency generator. Via an intermediate piece the transducer excites an amplitude transformer which is so designed as to step up the supersonic amplitude. Connected thereto is a cylindrical workhead serving as a probe and preferably ending in a calice-shaped tip designed so as to prevent the drillhead from bogging down. By the high-frequency motions produced by the tip of the probe the stone is eventually pierced through, provided a certain amount of pressure is also applied. Moreover, provision has to be made for a liquid layer to improve the effect of coupling. Apart from these shortcomings, the temperature of the working probe rises in the process so that its diameter cannot be less than a few millimeters. It is therefore, difficult to employ this method in the ureter. Yet another drawback stems from the necessity of continuously tuning this system since the natural vibration of the probe varies as a function of length and of the surrounding medium.

It is the object of the present invention to provide a device by means of which stones in the bladder, in the ureter and in the kidneys can be destroyed without any risk whatsoever for the patient.

According to the invention, the driving element comprises a chamber filled with a liquid and closed by means of a membrane rigidly connected to the lithotriptor, two electrodes being inserted in the chamber in such a manner as to provide electric insulation. Electric flashovers of short duration can be released by means of the electrodes. This arrangement makes it possible to use a long, thin and flexible lithotriptor inserted through the urethra into the bladder or into the ureter by means of an endoscope having an appropriate aperture and a suitable steering means until such time when it comes into contact with the stone to be destroyed. Since no high-voltage lines are introduced in the patient's body, this method can be said to be reliable, easily and precisely applicable without the least risk for the patient. The hydraulic wave produced by means of the electric flashover does not directly affect the stone, but acts upon a membrane which transmits its motion to a long thin wire. The transducer supplies motion amplitudes of up to 1 millimeter. Since the pulses are of the shortest duration possible, it is not necessary to particularly modulate the length of the lithotriptor irrespective of whether the probe is operated in air, water or any other medium.

To ensure a continuous exchange of liquid, the chamber is preferably provided with a feed pipe and a drain pipe protruding into same, both pipes being closed at their front ends and provided with lateral apertures. Preferably the lithotriptor is guided within a thin ureter catheter connected to the interior of a cover plate located on the side of the membrane opposite the chamber, the rinsing liquid being supplied to the interior via a connecting pipe.

Further details of the invention will become apparent from the following description of a proven embodiment of the invention with reference to the accompanying drawing wherein

FIG. 1 is an axial cross-sectional view, and

FIG. 2 a horizontal cross-sectional view on line II--II of FIG. 1.

A long, thin and flexible lithotriptor 4 with a workhead 4' is connected to a membrane 3 forming the termination of a rigid chamber 1 filled with water. By the release of electric flashovers of extremely short duration via two opposite electrodes 6 introduced through insulating bushes 8 with special electrode heads 7, hydraulic shock waves are produced in the chamber by means of vaporization in the area of the arc, causing deformation of the membrane 3 for a short period of time. When coupled to an appropriately selected lithotriptor these membrane deformations can be transformed into longitudinal vibrations in the lithotriptor. In order to keep the conductivity increase of the liquid due to electrochemical and photochemical reactions as low as possible, the liquid in the chamber is continuously exchanged through the feed and drain pipes 9, 9'. The feed and drain pipes are closed at their front ends and provided with lateral apertures 10 so as to preclude the direct escape of pressure waves.

The membrane 3 rests on a gasket 11 inserted in the planished front end of the chamber 1, tightly closing the same after it has been clamped down by means of a cover plate 2 of particular design and a clamping ring 5. In order to avoid disruption of the connection between the lithotriptor and the membrane as a result of buckling, the cover plate is provided with a cylindrical guiding means for the lithotriptor.

For the destruction of stones in the ureter, the lithotriptor 4 is guided inside a thin ureter catheter 12 which on the one hand, serves as a means for centering the lithotriptor, and on the other hand as a means for supplying the workhead with liquid between the catheter and the lithotriptor. The ureter catheter is fixed in the guiding portion of the cover plate. The rinsing liquid can be introduced into the interior 14 of the cover plate 2 through a connecting pipe 13 on the cover plate.

Claims

We claim:

1. A device for destroying stones in the bladder, in the ureter, in the kidneys and the like, comprising a housing open on one side, a cover plate mounted on the open side of the housing and having a central crossbore, a membrane clamped between the cover plate and the open side of the housing, said membrane defining a chamber within the housing, said chamber being tightly closed and filled with a liquid, an ureter catheter, one end of it fitted in said crossbore of the cover plate, the other end of the catheter being insertable through the urethra into the interior of the body, an elongated flexible lithotriptor penetrating the catheter in longitudinal direction, one end of the lithotriptor being rigidly connected to the membrane, the other end of the lithotriptor contacting the stone to be destroyed, two crossbores penetrating the housing on opposite sides in transverse relation to the catheter, two electrodes inserted in said crossbores of the housing and electrically insulated from the housing, the inner ends of said electrodes being opposed to each other at a distance, and electrical means for the production of electric flashovers between said inner ends of the electrodes.

2. A device according to claim 1, wherein a feed pipe and a drain pipe are inserted in the chamber in such a manner as to protrude into same, the feed pipe and the drain pipe each being closed at its front end in the area of the chamber but provided with lateral apertures.

3. A device according to claim 1, wherein said cover plate defines an interior together with the side of the membrane facing away from the chamber, the ureter catheter being connected to the interior, a connecting pipe being provided on the cover plate for the supply of rinsing liquid to the interior and consequently to the ureter catheter.