Surgery – Instruments – Means for concretion removal
Reexamination Certificate
1999-03-30
2001-04-17
Jackson, Gary (Department: 3731)
Surgery
Instruments
Means for concretion removal
C606S127000, C606S170000
Reexamination Certificate
active
06217588
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a metallic flexible probe for use in lithotripsy and more particularly to a probe for use with an intracorporeal lithotripter of the kind as disclosed in U.S. Pat. No. 5,160,336 which is adapted to effect an intracorporeal fragmentation of calculi such as nephroliths, ureteroliths or urinary calculi by using an endoscope.
BACKGROUND OF THE INVENTION
U.S. Pat. No. 5,160,336 discloses an intracorporeal lithothripter having a handpiece which is adapted for holding a probe. The probe forms a waveguide which is adapted to transmit impact energy that is produced by a projectile. The projectile is pneumatically driven within a guide tube for periodically causing an impact force against the proximal end of the probe to thereby obtain shock waves at the distal end of the probe.
The efficiency of the probes as used with such lithotripters is dependent on the transfer of energy as well as also of the transformation of energy which is caused by the impact energy acting on the proximal end of the probe and being transmitted to its distal end as a shock wave resulting from such impact energy. The particular shock wave which is accordingly transmitted from a head portion to a tip portion of the probe may be considered as a repeating sequence of compressions and expansions whereby the propagation also results in a translational movement of the distal end of the probe which finally generates a deformation wave that causes the specific intracorporeal fragmentation of calculi. It is therefore to be understood that the geometric dimensions of the probe highly influence the propagation of the shock waves so that optimization of the geometric dimensions of the probe is considered as a very essential object in particular for use in a lithotripter operating with ultrasonic frequencies of the shock waves for obtaining a particle size of the calculi as fragmented by such a probe which for example may be flushed via a separate flush channel of the endoscope into which the probe has been inserted by the operator of the lithotripter.
The metallic probes which so far have been used in lithotripsy in combination with an intracorporeal lithotripter of the kind as mentioned above are usually provided with a uniform diameter of between 0.6 mm as a minimum and 3.2 mm as a maximum with an average length of the probe of about 500 mm. The probes having the smaller diameter may also be used with so-called flexible endoscopes which could also be provided with a controllable tip portion. The same mostly necessitates larger operation lengths of the probe of up to 700 mm and more for allowing a deflection of such flexible endoscopes in two directions with a circular measure by radians of up to 170°. For obtaining with such a large deflection of the endoscope a correspondingly high flexibility of the probe it already has been suggested in U.S. Pat. No. 5,449,363 to provide the probe with a flattening over the actual partial length which has to take up the deflection of the endoscope whereby the provision of such a flattening is at the same time intended to avoid any unwanted frictional contact with the surrounding wall of the lumen of the endoscope. It is further disclosed in this document that such a flattening could also allow a laser cutting or electrical discharge machining of slits at selected locations to further improve flexibility of the probe.
As the result of the relatively high stress and loading to which the head portion of the probes is exposed by the impact force as continuously produced by the pneumatically driven projectile there actually exists an enlarged risk of fractures at arbitrary portions along the length of the probe. Such fractures of the probe could lead to injuries of the patient in the course of an endoscopic treatment and could also result in damages of the wall of the working channel of the endoscope. The presence of such fractures when not timely noticed could as well tempt the operator to continue with the endoscopic treatment then even with a defective probe which would make the operation imperfect and possibly also incomplete.
SUMMARY OF THE INVENTION
The principle object of the present invention is to provide an improved probe for use more particularly in shock wave lithotripsy which will guarantee a more secure endoscopic treatment and which in general will also optimize the conditions for the transmission of the shock waves from the proximal end of the probe to its tip portion.
In accordance with the present invention a metallic flexible probe for use in lithotripsy of the kind as above referred comprises a head portion at its proximal end having a cross-section which is larger than a nominal diameter of the probe that corresponds to a predetermined lumen of an endoscope for use with an intracorporeal lithotripter, whereby a predetermined break point of the probe is provided next to its head portion and approximately at a transition to an adjoining initial length of the probe which is provided with the nominal diameter of the probe.
With the provision of such predetermined break point of the probe next to its head portion at the proximal end of the probe it should be understood that the same will have no influence on the main body of the probe extending to its tip portion at a distal end so that this main body of the probe may be designed with supplemental features in accordance with the present invention which will serve more or less the object of optimizing the transmission of the shock waves to the distal end of the probe for the purpose of an intracorporeal fragmentation of calculi as a result of the impact force and impact energy created by the pneumatically driven projectile of the lithotripter.
The predetermined break point of the probe could thusly be predetermined for example by a thermal treatment of the probe which in the vicinity of the transition to an adjoining initial length of the probe that is provided with the nominal diameter of the probe would locally weaken the strength of the probe. The predetermined break point could alternatively also be predetermined by a cross-section of the probe which in the vicinity of this specific transition is locally limited to a reduced value in comparision with the adjoining initial length of the probe and could therefore be provided for example by an indentation or a notch of the probe. Such a predetermined break point could as well be predetermined by an adhesive joint between the head portion of the probe and its adjoining initial length and as a still further alternative there could also be provided a crimp connection instead of or even supplementing such an adhesive joint.
When a predetermined break point is realised in this way then the head portion of the probe as well as its entire length may be designed in such a manner as to optimize the reception of the impact force as well as its transmission as a shock wave towards the distal end of the probe for the fragmentation of calculi. The efficiency factor of this fragmentation depends on the particular design of the probe. The initial length of the probe starting at its head portion should therefore be designed with the nominal diameter mainly under the aspect that with the propagation of the shock waves along this initial length also all existing transfer losses of the impact energy will be minimized. If most of the impact energy without any substantial transfer losses will thusly be available at the distal end of the probe this will then guarantee a most effective fragmentation of calculi without any appreciable risk of injury for the surrounding tissue so that the remaining length of the probe could then be designed with dimensional features that primarily influence the flexible behaviour of the probe without any negative influence on the propagation of the shock waves.
Under a more specific aspect of the present invention the probe is therefore preferably provided with an intermediate partial length next to its initial length having a diameter which is continuously reduced to a slightly smaller diameter at an intermediate d
Goin Emanuel
Horn Uwe
Jerger Thomas
Menne Andreas
Ferton Holding S.A.
Jackson Gary
Ratner & Prestia
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