Surgery – Devices transferring fluids from within one area of body to...
Reexamination Certificate
2001-04-26
2003-09-16
Look, Edward K. (Department: 3754)
Surgery
Devices transferring fluids from within one area of body to...
C604S096010
Reexamination Certificate
active
06620122
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to gastric pseudocyst drainage and relates more particularly to a novel method for draining gastric pseudocysts and to a novel stent delivery system for use in said method.
A gastric or pancreatic pseudocyst is an aggregation of tissue, fluid, debris, pancreatic enzymes and blood that often develops in the peritoneal cavity after the onset of acute pancreatitis. Although many pseudocysts resolve themselves spontaneously, some pseudocysts become quite large and require treatment due to the unwanted pressure they exert against the stomach and/or neighboring organs.
One approach to treating gastric pseudocysts involves surgery and typically comprises (i) cutting through the abdominal wall of the patient to permit access to the pseudocyst through the abdominal wall, (ii) perforating or puncturing the pseudocyst, (iii) inserting a drainage tube into the pseudocyst through the perforation to allow the contents of the pseudocyst to empty through the drainage tube to a point external to the patient, (iv) removing the drainage tube from the patient once the pseudocyst has been emptied, and (v) repairing the abdominal wall.
As can readily be appreciated, the surgical approach described above is invasive and has easily identifiable drawbacks associated therewith, such as an appreciable risk of infection.
More recently, an endoscopic approach to treating gastric pseudocysts has been devised. This approach is less invasive than surgery and typically involves inserting an endoscope through the patient's mouth and into the patient's stomach. The endoscope is first used to visually locate the pseudocyst on the opposite side of the stomach wall. A needle or sphincterotome is then extended through the distal end of the endoscope to perforate both the stomach wall and the pseudocyst. A contrast agent delivered through the endoscope is then injected into the pseudocyst, and a cystogram is endoscopically performed to confirm entry into a pseudocyst (as opposed to entry into the peritoneal cavity). Following confirmation of entry into a pseudocyst, a guide wire is advanced through the endoscope and into the pseudocyst. Next, a balloon catheter is advanced through the endoscope and over the guide wire into the pseudocyst. The balloon is dilated to enlarge the perforations in the pseudocyst and the stomach and is then deflated and withdrawn. A plurality of straight endobiliary tubes of fixed diameter (each approximately 10 Fr) are then endoscopically implanted across the pseudocyst and stomach perforations to allow the contents of the pseudocyst to drain into the stomach, said biliary tubes being arranged in a side-by-side fashion and being implanted one at a time. The endoscope is then removed from the patient. When drainage is complete (typically within a few weeks), the endoscope is reintroduced into the patient, and the biliary tubes are withdrawn from the patient through the endoscope using a snare.
Although the aforementioned endoscopic approach has certain advantages over the surgical approach described above, the foregoing endoscopic approach still suffers from certain drawbacks. One such drawback is that the biliary tubes presently used are relatively small in diameter and have a tendency to become occluded during use. Such occlusion is due, in part, to the inward radial pressure exerted by the pseudocyst and stomach walls against the tubes, and is due, in part, to the viscous nature of the materials conveyed within the small diameter tubes. Another drawback is that the biliary tubes used are susceptible to dislodgement from the pseudocyst and/or the stomach because they are straight and lack anchoring means. Still another drawback is that a second endoscopic procedure is needed to remove the biliary tubes from the patient following drainage of the pseudocyst. Still yet another drawback is that a multitude of different catheters or other devices must be sequentially inserted into the endoscope to enable the various steps outlined above to be performed.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a novel technique for draining gastric pseudocysts.
It is another object of the present invention to provide a technique as described above that overcomes at least some of the above-described shortcomings associated with existing techniques for draining gastric pseudocysts.
Therefore, in furtherance of the above and other objects to be described or to become apparent from the description below, there is provided herein a method of draining a pseudocyst present within a patient, said method comprising, according to one aspect, the steps of (a) providing a stent, said stent being transformable from a non-expanded state of comparatively lesser diameter to an expanded state of comparatively greater diameter, said stent having a first end and a second end; (b) delivering said stent in said non-expanded state to a pseudocyst located within a patient; (c) inserting said first end of said stent into the pseudocyst; and (d) transforming said stent from said non-expanded state to said expanded state; (e) whereby the pseudocyst drains through said stent.
Preferably, the aforementioned method further comprises the steps of inserting said second end of said stent into the stomach of the patient whereby the pseudocyst drains through said stent into the stomach and, prior to said first end and second end inserting steps, forming a perforation in each of the pseudocyst and the stomach, wherein said first end inserting step comprises inserting said first end of said stent through said perforations in the pseudocyst and the stomach. Moreover, the stent is preferably introduced into the stomach of the patient intraorally.
The above-described stent may be a self-expandable stent or may be a balloon-expandable stent. In the case of a self-expandable stent, said delivering step comprises maintaining said stent in said non-expanded state using a removable restraint, and said transforming step comprises removing said removable restraint from said stent to allow said stent to self-expand. The self-expandable stent, which is preferably made of a braided filamentary material, may be shaped to include a waist of comparatively lesser expanded diameter (e.g., 8-10 mm) and a pair of cuffs on opposite ends of said waist of comparatively greater expanded diameter (e.g., about 15 mm) or may have a uniform relaxed diameter. The self-expandable stent may be made of a biocompatible nonabsorbable material, such as a metal or a plastic, or may be made of a bioabsorbable material.
Where the stent is a balloon-expandable stent, said balloon-expandable stent is preferably a covered balloon-expandable stent. In addition, said delivering step preferably comprises mounting said balloon-expandable stent, in said non-expanded state, over a deflated balloon catheter and then inserting said deflated balloon catheter into a patient in the area of a pseudocyst. Said transforming step preferably comprises inflating said deflated balloon catheter until said balloon-expandable stent is transformed from said non-expanded state to said expanded state.
Where the stent, whether self-expandable or balloon-expandable, is nonabsorbable, the method preferably further comprises the step of endoscopically removing said stent with a snare after drainage of the pseudocyst is complete.
According to another aspect of the invention, there is provided a method of draining a pseudocyst present within a patient, said method comprising the steps of (a) providing a double pigtail stent, said double pigtail stent having a first end and a second end, each of said first and second ends being transformable from a straightened state, when constrained, to a curled state, when relaxed; (b) coaxially mounting said double pigtail stent over the distal end of a catheter, whereby each of said first and second ends is in said straightened state; (c) endoscopically introducing said double pigtail stent and the distal end of said catheter through the mouth and into the stomach
Richardson M. Kevin
Stinson Jonathan S.
Fristoe, Jr. John K
Kriegsman & Kriegsman
Look Edward K.
Sci-Med Life Systems, Inc.
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