Lithotripsy Probe

1. Field of the Invention

This invention relates to a lithotripsy probe for stone disintegration comprising two mutually insulated conductors surrounded by a thin metal sleeve over a distal length thereof.

2. Description of the Prior Art

In the case of lithotripsy probes of the aforesaid kind which have been utilised hitherto, the metal sleeve could split throughout its length with excessive or incorrect use, e.g. in the case of more than 200 spark discharges. This split is caused by the fact that the two conductors of the probe are moved apart by the spark discharges and thereby lead to eventual tearing of the thin metal sleeve. Since there is no firm joining of the sleeve with the insulation of the conductors, the metal sleeve can under particular conditions separate from the distal extremity of the probe during the withdrawal of the probe out of the bodily cavity and remain in the patient's bodily cavity, which represents a risk to the patient.

It is accordingly an object of the invention to secure the metal sleeve situated at the distal end of the probe on the two conductors, which are insulated from each other, in such manner that it is fixedly secured notwithstanding the utilisation period and the frequency with which the probe is used.

According to the invention, this object is achieved in that the case of the lithotripsy probe referred to in the foregoing, the metal sleeve is provided with an opening at least at one point, situated at a distance from the distal extremity of the probe, and a shrink-on tube surrounds the sleeve and through the opening engages the two insulated conductors to secure the sleeve on the two insulated conductors. The engagement of the shrink-on tube may be promoted by the application of heat so that the sleeve is held at all times, and in particular during withdrawal of the probe from the bodily cavity.

In this connection, it is advantageous according to a preferred embodiment of the invention to provide several perforations or to endow or provide the metal sleeve with a coil-shaped excision or the like, the pitch of which is of a size such that the shrink-on tube which is to be fitted over it bears at least partially against the conductor insulation via the excision.

According to another embodiment of the invention, it is also possible for the metal sleeve to comprise a coil spring closely wound around the conductors at the distal extremity of the probe which in continuation thereof comprises turns with an increased pitch such that the shrink-on tube can engage in gaps between the turns to immobilise the sleeve on the two conductors.

In this case too, an indetachable fitting of the metal sleeve on the conductor wires of the probe is established thanks to which it is no longer possible for a split metal sleeve to be stripped off upon withdrawing the probe from the bodily cavity.

Further features and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate a preferred embodiment of the invention.

In the drawings;

FIG. 1 is a side view of a lithotripsy probe with an axial cross-section of the distal extremity of the probe shown enlarged;

FIG. 2 is a side view of the metal sleeve utilised in FIG. 1, with helical perforations, and

FIG. 3 is a side view of a metal sleeve of modified form, which could also be used in the embodiment of FIG. 1.

The lithotripsy probe 1 for connection to a surge wave generator is traversed in a manner known per se by two conductors 3 and 4 insulated by sleeving 2. To this end, the distal extremity is surrounded by a small thin metal tube or sleeve member to assure a constant electrode or conductor spacing during utilisation of the probe.

In accordance with the invention, the distal end of the probe has installed on it a thin metal sleeve 5 which is provided at a short distance from the distal extremity with at least one aperture or perforation and in the case of FIGS. 1 and 2, with perforations in the form of a pair of helical excisions to form a perforated section 6. This metal sleeve 5 has fitted over it a shrink-on tube 7 which under the application of heat is deformed elastically to engage in the excisions and bears directly against the insulating sleeving 2 of the two conductors 3 and 4. Thanks to this arrangement, the metal sleeve remains firmly joined to the two conductors 3 and 4 even in the case of possible splitting.

It is also possible to use a metal sleeve as shown in FIG. 3, in the form of a spring comprising turns 8 closely wound around the probe at its distal extremity, which are then proximally followed by turns 9 with an increased pitch to form gaps between successive turns. The shrink-on tube 7 which is to be fitted over the spring may penetrate between the turns 9 and bear against the insulations 2 of the two conductors 3 and 4, so that the metal sleeve is always held fast.