Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1997-03-26
2002-04-02
Stright, Jr., Ronald K. (Department: 3762)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S008000, C604S096010, C604S104000, C604S544000
Reexamination Certificate
active
06364868
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a device and method by which a human ureter may be made to expand to form what is known as a megaureter. In addition, this invention describes a device which will accomplish this without injury to the kidney.
BACKGROUND OF THE INVENTION
The term “megaureter” refers to a large, ectatic, dilated ureter, a condition may be congenital or acquired. It is the end result of increased hydrostatic pressure in the ureter from obstruction to the flow of urine, reflux of urine from the bladder back into the ureter (known as vesicoure-teral reflux), or for reasons unknown (i.e., idiopathic). Although megaureter is considered to be a pathologic condition, current medical advances in the field of urinary tract reconstruction have led to the recognition of certain circumstances in which the existence of a megaureter is desirable. A detailed description of urinary tract anatomy and the fundamentals of megaureter may be found in J. N. Kabolin, “Anatomy of the Retroperitoneum and Kidney”,
Campbell's Urology,
Ed.6, W. B. Saunders Co., 1992, pp. 3, 36-40 and L. R. King, “Vesicoureteral Reflux, Magaureter, and Ureteral Reimplantation”,
Campbell's Urology,
pp. 1689-1742.
Yearly, several thousand individuals undergo surgical reconstruction of the urinary tract. Reasons for requiring urinary tract reconstruction vary greatly and include: cancers of the urinary tract such as bladder or ureter, congenital defects such as bladder exstrophy, and poorly compliant, small capacity bladders (causing urinary incontinence and renal failure) often seen in paraplegics or patients with posterior urethral valves. The surgical procedures performed vary greatly, though common to all these procedures is the frequent necessity of utilizing segments of the gastrointestinal tract in the reconstructive process.
In the past virtually all segments of the gastrointestinal tract have been used successfully in the reconstruction of the urinary tract. Unfortunately, the incorporation of tissue from the gastrointestinal tract into the urinary tract predisposes the patient to several problems. These problems involve anatomic and physiologic deficiencies of the gastrointestinal tract subsequent to the removal of various lengths of intestine (i.e., malabsorption, diarrhea, and vitamin or bile salt deficiencies). Also, problems inherent in combining the gastrointestinal and urinary tracts include mucous production by intestinal mucosa, enhanced bacterial growth with frequent urinary tract infections, pyelonephritis, abnormal electrolyte and acid reabsorption, urinary stone formation, and occasionally even cancer formation. Further descriptions and fundamentals of urinary tract reconstruction (i.e., urinary diversion and bladder augmentation) can be found in
Campbell's Urology:
W. S. McDougal, “Use of Intestinal Segments in the Urinary Tract: Basic Principles”, pp. 2595-2629, and M. E. Mitchell et al., “Augmentation Cystoplasty Implantation of Artificial Urinary Sphincter in Men and Women and Reconstruction of the Dysfunctional Urinary Tract”, pp. 2630-2653.
Extensive research has been carried out in an effort to identify an alternative to the gastrointestinal tract in the reconstruction of the urinary system. Ideas have included use of muscle flaps and fascia, harvesting cells of the urinary tract (i.e., urothelium) and cultivating them over bio-absorbable polymers, and transplantation of urothelium from human donors or animals. To date these approaches and others have been seuboptimal.
Recently, however, several medical investigators, have described the use of native urothelium from megaureters to reconstruct the urinary tract (Churchill, B. M., Aliabadi, H., Landau, E. H., McLorie, G. A., Steckler, R. E., McKenna, P. H., Khoury, A. E. “Ureteral Bladder Augmentation”,
Journal of Urology,
150: 716-720, 1993; Hitchcock, R. J., Duffy, P. G., Malone, P. S., “Ureterocystoplasty: The ‘Bladder’ Augmentation of Choice”,
British Journal of Urology,
73(5): 575-579, 1994). Each of these authors concluded that when possible, bladder augmentation using ureteral tissue from dilated ureters yielded the best outcome, with reduction in the complications common to all reconstructions utilizing the intestinal tract. of course, the feasibility of this operation was contingent upon the patient already having a megaureter. Thus, their experience was restricted to those select patients who, ironically, were “fortunate” enough to have the pathologic entity of megaureter. Unfortunately, this represents only a small fraction of the population in need of urinary tract reconstruction. Also, since most of these patients had poorly functioning kidneys associated with megaureter, nephrectomy (i.e., removal of the kidney) or partial nephrectomy (i.e., removal of a portion of the kidney) was performed in the majority of cases reported.
Thus, there is a need to develop a device and method by which a megaureter could be produced in a controlled, monitored setting while maintaining the physiologic integrity of the associated kidney. To date there is no known device or method which will allow a megaureter to be produced iatrogenically without jeopardizing the kidney in a patient requiring urinary tract reconstruction. This could be accomplished with the invention described below which is a method utilizing a ureteral catheter which combines a urinary drainage tube and a tissue expander.
Tissue expanders are reservoirs which can contain varying volumes of either gaseous or liquid materials. Usually constructed of rubber, latex, or silicone elastomers, tissue expanders are extremely pliable, enabling them to be filled to very large volumes while maintaining low pressures within the reservoirs themselves. To date, the most common use of tissue expanders is in the field of plastic surgery, where they are often implanted under the skin and gradually (i.e., over the course of weeks to months) expanded to stretch the overlying skin. Once the tissue is stretched to the desired surface area, the tissue expander may then be deflated and removed. The overlying stretched skin can then be used to cover many types of large wounds ranging from those rendered with the excision of large unsightly scars or tattoos to wounds sustained in avulsion injuries, amputations, or burns.
Tissue expanders differ from the simple “balloons” placed at the ends of conventional urinary catheters (e.g., the “Foley” catheter), which serve the purpose of maintaining a catheter in a certain position or preventing a catheter from becoming dislodged. Also, several ureteral catheters which incorporate balloons are currently in production. For instance, the Microvasive Corporation of Natick, Mass. produces several ureteral dilation products. However, these catheters are not meant to dilate the ureter slowly over several days, weeks, or even months under low pressures (i.e., below diastolic pressure) to achieve large volumes (i.e., three to six hundred milliliters or volumes comparable to normal human bladder capacity) but, rather, are meant to rapidly dilate the ureter to allow stones to pass, rupture strictures in the wall of the ureter, or allow passage of larger bore ureteral instruments. Microvasive's product catalogues describe the nature of the balloons on the ureteral dilation catheters as “noncompliant,” able to withstand dilation pressures of up to ten or more atmospheres while maintaining balloon diameters ranging from four to ten millimeters.
Tissue expanders have fluid reservoirs which function as carriers of large capacities while maintaining low pressures inside the walls of the reservoirs themselves. This unique property of tissue expanders, which is attributable to the extremely elastic and complaint substance from which they are made (usually silicone elastomer), is an important feature that is crucial in preventing the ischemia and necrosis of surrounding tissue. So unique is this quality of tissue expanders that a multitude of patents have been issued for various tissue expanders and breast protheses. For instan
Cowan Liebowitz & Latman P.C.
Dippert William H.
Stright Jr. Ronald K.
The Trustees of Columbia University in the City of New York
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