Anti-refluxive internal ureteral stent with a dynamic hood-valve

Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Bone

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Details

623 2, 623 11, 604323, 604264, 604281, A61F 204

Patent

active

050191020

DESCRIPTION:

BRIEF SUMMARY
The invention concerns an anti-refluxive internal ureteral stent in accordance with the preceding patent claims.
Internal ureteral stents are customarily used to conduct urine out of the pelvic-calceal system into the bladder when normal urine transport is compromised
by constriction of the ureter, for instance by scar formation, external encroachment of congenital stricture
or by obstruction of the ureteral lumen, for instance by urinary calculus, clot or tumor.
The purpose of such stents is to guard against the threat of damage to the renal parenchyme from persistently high pressure, and to prevent life-threatening infection of the "stagnant waters" in the upper urinary tract.
Internal ureteral stents in present use are tube-shaped, synthetic catheters with curvature at both ends, the radius of the upper coil, above the uretero-pelvic junction, being smaller than that of the lower coil in the bladder, in order to block dislocation in either direction. The stents carry numerous lateral (punched) perforations, particularly in the portions to be positioned in the renal pelvis and the bladder, guaranteeing inflow and outflow during lengthy indwelling periods, and in case of incrustation of single openings. In order check positioning, the synthetic catheters give X-ray contrast, by using radio-opaque material either for the entire tube or for a longitudinal skein in the wall of the tube.
The insertion of customary ureteral stents is occasioned by threading in a much longer and considerably stiffer guide-wire to straighten the forementioned curvatures. Retrograde insertion of the stent catheters is carried out through the working port of a cystoscope under visual and fluoroscopic guidance, threading them into the lower ureteral outlet--the ostium--and advancing them up the ureter with the help of the guide-wire. A second synthetic tube is threaded onto the guide-wire, reaching from the end of the ureteral catheter almost to the end of the guide-wire, thus leaving the latter free for manipulation. When the internal ureteral catheter is correctly placed, the free end of the second synthetic tube is fixed by hand and the guide-wire is drawn out through its lumen. During this extraction, the vesical end of the stent is braced against the synthetic tube, so that friction in the coiled portions does not extract the stent catheter from the ureter along with the guide-wire. This procedure is carried out under visual cystoscopic guidance; as soon as the guide-wire lies only in the outer synthetic tube--the stop-tube--the vesical end of the stent is freed and coils up in the bladder as dictated by the vesical curvature.
Safeguarding urinary outflow to the bladder to date with customary internal catheter stents is bought at the expense of periodically recurrent, unphysiological pressure peaks in the upper urinary tract. The unimpeded patency of such stents abolishes the anatomical valve function of the lower ureteral orifice, or ostium, which normally protects against urinary reflux. This leads to continuous transmission of any pressure increases in the bladder lumen into the pelvio-calyceal system by reversed urine flow, or reflux. As a result, the patients provided with such stents frequently suffer severe pain. On the one hand, the transmission of the sudden pressure rise during micturition activates stretch receptors in the renal pelvic wall, whose irritation is perceived as pain similar to colics. On the other hand, the presence of foreign bodies in the bladder--and the vesical portion of such stent catheters is a foreign body--frequently leads to painful bladder cramps by irritation of the bladder wall. The pressure waves of these cramps are then perceived as flank pain on the side with an indwelling stent catheter. These patients often are simultaneously treated for obstructive micturition disorders by transurethral catheterization, presenting an access port for germs, which then may unimpedely ascend, with the infected urine, along the internal ureteral catheter, occasionally causing life-threatening infection of

REFERENCES:
patent: 3965900 (1976-06-01), Boedecker
patent: 3999551 (1976-12-01), Spitz et al.
patent: 4334327 (1982-06-01), Lyman et al.
patent: 4512770 (1985-04-01), Cianci et al.
patent: 4574806 (1986-03-01), McCarthy
patent: 4643732 (1987-02-01), Pietsch et al.
patent: 4671795 (1987-06-01), Mulchin
patent: 4685905 (1987-08-01), Jeanneret nee Aab
patent: 4759758 (1988-07-01), Gabboy

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