Surgery – Instruments – Means for concretion removal
Reissue Patent
1997-09-12
2001-01-16
Dawson, Glenn K. (Department: 3761)
Surgery
Instruments
Means for concretion removal
C606S127000
Reissue Patent
active
RE037024
ABSTRACT:
BACKGROUND OF THE INVENTION
I. Field of the Invention
This invention relates generally to a lithotripsy device for breaking stones in the urinary tract or gall bladder, and more particularly to such a device having an elongated flexible stone impacting member designed to be passed through the working lumen of a steerable endoscope for applying a breaking force to renal or gall bladder calculi (stones) to mechanically break them to a size that can be more readily passed.
II. Discussion of the Prior Art
Over the past 15 years or so, the management of renal stones in the urinary tract has undergone radical change. In many instances, in the late 70's, open surgical removal was the principal mode of treatment for urolithiasis and cholecystolithiasis. In about 1980, percutaneous techniques, ureteroscopy and extracorporeal shock wave lithotripsy (ESWL) began to be used by urologists to successfully treat patients with renal calculus (stones). During the 1980's there have been a significant number of technical advances in the use of ESWL. Nonetheless, there still remains a need for endoscopic treatment of ureteral and renal calculi using ureteroscopy or percutaneous nephrolithotripsy, depending upon the location of the stone, its size and composition.
Various methods of endoscopic stone fragmentation have been discussed in the literature. In a paper by Reuter, et al., entitled “Electronic Lithotripsy of Utereal Calculi” published in the Journal of Urology in 1973, there is described an electrohydraulic lithotrite in which a spark induced shock wave travels through a fluid medium to the calculus to be fragmented. Electrohydraulic lithotripsy, however, is considered by some authors to be the most dangerous type to use.
There is also a laser device used in the endoscopic treatment of patients having renal stones. Here, a flexible or semi-rigid endoscope is used to transmit laser energy to the stone to be fragmented. However, it has been found that while laser probes are smaller in diameter and more readily insertable into the urinary tract, they do not have difficulty in fragmenting dense, poorly fragile calculi, such as calcium oxalate, monohydrate or cystine stones. Moreover, laser systems tend to be very costly, limiting their availability to major medical centers.
In about 1990, a pneumatically driven lithotrite referred to as the “Swiss Lithoclast” has been used and reported on by a number of urologists. The device in question is more particularly described in the Favre U.S. Pat. No. 5,160,336. It includes an elongated wire having an anvil on one end thereof which acts as a wave guide to transmit shock waves, created by a pneumatically driven bullet-like projectile striking the anvil, to a stone to be fragmented. The wave guide is adapted to be inserted through the working lumen of an endoscope for accurate positioning of the distal end thereof against the stone to be reduced.
There still remains a need for a more efficient endoscopic lithotripsy device for treating difficult stones, which are located in areas of the body that are hard to reach. Such a system must be capable of delivering high energy impacts while still capable of operating within the working lumen of small diameter flexible, steerable endoscopes.
It is accordingly a principal object of the present invention to provide a new and improved endoscopic lithotriptor.
Another object of the invention is to provide an endoscopic lithotriptor having a highly flexible stone impacting member, capable of passing through the lumen of an endoscope such as an ureteroscope or a nephroscope of conventional design.
Still another object of the invention is to provide a lithotriptor device capable of delivering a greater blow to a stone to more effectively fragment the stone.
Yet another object of the invention is to provide an improved pneumatic driven lithotriptor that is relatively small in size and attachable to an endoscope with which it is to be used without detracting from the ability of the urologist to view the site and manipulate the working end of the lithotriptor.
SUMMARY OF THE INVENTION
An intracorporeal lithotripsy device in accordance with the present invention comprises an elongated flexible, stone impacting member in the form of a metal wire having a distal end for engaging a calculated and a proximal end adapted to be struck by a hammer device. An elongated flexible sheath may be used to surround the stone impacting member over substantially its entire length and would have an outer diameter allowing its insertion through the working lumen of an endoscope. While the inclusion of the sheath has been found to enhance performance of the device, it is not essential to the effective operation of the present invention. Cooperating with the proximal end of the stone impacting member is a pivotally mounted mass comprising a swinging hammer device for repetitively applying an impact force to the proximal end of the wire. The hammer is pivotally mounted in a pneumatic chamber. Specifically, the hammer member is secured by a hinge pin within a cylindrical chamber and swings about the pin between a first “ready” position and a second “impacting” position in contact with the proximal end of an elongated wire stone impacting member. A means is provided for pneumatically driving the hammer member from its first position forcefully against the end of the wire in the second position to drive the proximal end of the wire against a stone to be divided and for returning the hammer member to its first position in anticipation of the administration of a subsequent blow to the wire.
The stone impacting member preferably comprises a stainless steel or Nitinol wire, each of which is capable of conforming to the shape of a flexible, steerable endoscope with which the lithotripsy device is to be used. The proximal end of the wire preferably has an anvil or striking surface affixed to it. As indicated above, the sheath surrounding the elongated wire is sized to pass through the working lumen of an endoscope and is preferably made from a lubricous plastic material, e.g., Teflon, so as to reduce frictional dampening of the wire even when the sheath and its enclosed wire stone impacting member are bent to some degree.
The cavity defining the pneumatic chamber is partitioned into three segments, the first being arcuate to accommodate the pivoting or swinging motion of the hammer member, the second being a large volume capacitance segment in fluid communication with the arcuate segment through a narrow slit located adjacent the first position and the third being a pressure relief segment in fluid communication with the arcuate segment proximate the second position. Surrounding the slit is a lip seal which cooperates with the hammer when in its “home” position. A source of pressurized air is introduced into the capacitance chamber while the pressure relief segment is exposed to the ambient or to a negative pressure. The lip seal prevents the arcuate segment from becoming pressurized prior to release of the hammer. When the hammer member is triggered, it thus sweeps through an arcuate path, forcefully striking the proximal end of the wire or the anvil member secured thereto and for translating the wire within its sheath and driving its distal end against the calculus to be fractured.
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Brust Thomas E.
Ley Timothy J.
Boston Scientific Corporation
Dawson Glenn K.
Testa Hurwitz & Thibeault LLP
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