Patent Application
20120059387
1. Field of Invention
This invention pertains to removable stents. More particularly it relates to a delivery system and method for the placement of removable stents into urethra obstructed by enlarged prostates to alleviate restrictions in the prostatic urethra.
2. Description of Related Art
For many men, as they age, the prostate is enlarged restricting the prostatic urethra resulting in difficulties in emptying the bladder. Even slight constipation can aggravate the situation making it difficult for a person to begin urinating or emptying the bladder. A number of removable stents to relieve this condition are known.
McIntyre et al., U.S. Pat. No. 5,833,707 issued Nov. 10, 1998 discloses a removable stent for temporarily implanting an intraluminal stent in a body lumen and its subsequent removal, which operates in a manner similar to your device. McIntyre et al has an extending rolled coil design, which coils the stent into a sheath at the end of the removable catheter.
An et al., U.S. Pat. No. 6,241,757 issued Jun. 5, 2001 discloses an hour glass shaped stent with flared ends to prevent the stent from moving. Its mesh construction is used in many applications, rather than the solid stent you have in mind.
Heath, U.S. Pat. No. 7,101,392 issued Sep. 5, 2006 discloses another tubular stent made of a metal filament material with an outer member having an exposed outer surface and a core within the extended member formed of a different metal. This stent is balloon expanded and is made of a radio-opaque material to check its placement with x-rays, etc.
Reever, U.S. Pat. No. 6,790,223 issued Sep. 14, 2004 discloses a delivery system for placement of an expanding coil stent. This coil stent is dipped in liquid silicone to coat the coil segment with a webbing to prevent tissue ingrowths. A number of different types of coatings may be employed in this regard. Reever also mentions that a number of stents are positioned using an endoscope.
Robertson, U.S. Pat. No. 6,949,125 issued Sep. 27, 2005 discloses a Urethral Stent, which extends into the bladder.
Lennox et al., U.S. Pat. No. 6,494,879 issued Dec. 17, 2002 discloses a urethral prosthesis with first and second tubular elements: the first extending into the bladder into the bladder and the second holding open the urethra for relief of urinary retention.
Gellman, U.S. Pat. No. 7,527,651 issued May 5, 2009 discloses another two part stent located on either side of the external sphincter to inhibit migration while not interfering with the normal functioning of the sphincter.
The invention described below provides a practical non-intrusive stent for removing the obstruction of the flow of urine caused by enlarged prostate blockage.
The present invention comprises a delivery system for placing a urethra stent within the urethra of a patient at the point of obstruction by an enlarged prostate. It comprises a stent and flexible stent inserter. The stent inserter has a shaft of a length to be inserted within the urethra and extend to the bladder. It has first and second ends and defines a liquid passageway there between for transporting liquids with an inlet and outlet. It also has a combination air/liquid passageway there between for transporting air/liquids with an inlet and outlet.
The first end of the stent inserter has an expandable securing segment defining an interior liquid reservoir. The liquid reservoir is in communication with the outlet of the liquid passageway to expand/contract the securing segment in response to pressure changes in the liquid passageway. The securing segment is structured to expand and hold a stent placed on the securing segment for positioning when expanded, and to contract and release the stent in place within a segment of the urethra when contracted.
A ballooning positioning tip is located proximate the securing segment and has an interior air/liquid reservoir in communication with the outlet of the combination air/liquid passageway. The positioning tip is structured to inflate/deflate with either air to form a contrast media balloon for ultrasound location and positioning of the securing segment with stent, or liquid. When inflated with liquid, the tip expands and unblocks obstructed portions of the urethra for placement of the stent.
The second end of the stent inserter contains inlets of the liquid passageway and inlets of the air/liquid passageway.
An hourglass shaped stent with an interior channel is structured to fit over the positioning tip and secured onto the securing segment. The hour glass shaped insures that the stent will remain in place in the urethra until removed. When secured, the stent is then placed within an obstructed segment of the urethra to allow urine to pass through the interior channel, when the stent inserter is removed. This stent interior channel may have rippled or roughened frictional surfaces to create better contact grip with the securing segment of the stent inserter to aid in its removal when the temporary blockage has subsided. For stents implanted longer, they may be made of an antibiotic impregnated silicone or other material resistant to bacterial adhesion. This prolongs the life of the stent by reducing tissue overgrowth.
A liquid filled inflation/deflation pump, such as a retractable syringe or squeezable bulb with an internal liquid reservoir with an opening is operably associated and is in communication with the inlet of the liquid passageway. For example, the squeeze bulb consists of a balloon made from resilient rigid material. When it is squeezed, the fluid inside is forced out. Releasing the bulb sucks fluid back in. A valve may be associated with the opening to adjust the flow of fluid, if needed.
The squeezable bulb, when compressed, forces liquid from the internal liquid reservoir through the liquid passageway to inflate the expandable securing segment to hold thereon a stent during positioning and insertion. The retractable squeezable bulb is then released to retract and deflate the securing segment to release the stent within the urethra to allow urine to pass through its interior channel.
A valve controlled air/liquid filled inflation/deflation pump, such as a retractable syringe or squeezable bulb is operably associated and in communication with the inlet of the air/liquid passageway. It has an internal reservoir initially filled with liquids and is capable of being interchanged with an internal air reservoir to selectively fill the air/liquid passageway with air. When squeezed, the air/liquid filled retractable squeezable bulb selectively forces either air from an air source to inflate the ballooning positioning tip with air in one mode or with liquids in another mode to unblock obstructed portions of the urethra for placement of a stent. After inflation, the air or liquids are withdrawn from the positioning tip, allowing removal of the stent inserter.
For example, a liquid filled squeezable air/liquid squeeze bulb with an internal liquid reservoir is in communication with the internal air/liquid passageway of the flexible inserter. A valve is included, which can selectively allow ambient air to be drawn into the internal liquid reservoir. In a sense, the air/liquid squeeze bulb is an example of a simple pump to force either air or liquids into the reservoir for pumping of gases or fluids.
The stent inserter is used by squeezing the air/liquid squeeze bulb to force first liquid from the liquid reservoir through the air/liquid passageway to inflate the ballooning positioning tip structured to force open obstructed segments of the urethra for placement of the stent. To locate where the stent is placed within the urethra near the bladder, the ballooning positioning tip is then filled with air to provide contrasting media for ultrasound location. If the stent is not at the desired location, the ballooning positioning tip is deflated and the process is repeated until the stent is located in a desired area. The ballooning positioning tip is then contracted for placement of the stent and removal of the stent inserter.
Selectively activated valves are associated with ambient air or liquid reservoirs to inflate the ballooning tip with air or liquids. Preferred valves are luer lock valves, septum vales, or push button valves, which allow either air or liquids to be selectively forced through the air/liquid passageway.
Although other contrasting media gases could be employed in the reservoirs and passageways for location of the stent, air is safe to handle and readily abundant. Similarly, other inflation liquids could be used, but water is safe to handle and readily abundant. Also, other types of air/liquid reservoirs could be used, such as plunger syringes associated with Luer lock valves.
The stent inserter system and stent thus provides a simple to use device, which allows placement without the need for a fluoroscope. In addition, as urologists usually have ultrasound equipment in their offices, and are familiar with Luer lock valves, the device avoids the need for resort to another facility to perform the stent insertion procedure. The stent inserter system and stent provides a viable, practical non-intrusive solution performed in a doctor's office, which is as simple as inserting or removing a catheter.
Attached to the other end of the stent inserter 10 is a squeezable bulb 20 with an interior liquid reservoir 21 in communication with the liquid passageway 12. The liquid passageway 12 is approximately 25 mm in diameter at the end connected to the squeezable bulb 20, and narrows to 4.0 mm at its upper end within the stent securing end 16. The squeezable bulb 20 is filled with water. When the bulb 20 is squeezed it creates hydraulic pressure that travels through the liquid passageway 12 increasing in pressure at the end of the narrowing liquid passageway 12 to expand the stent securing end 16 of the stent inserter 10.
A stent 22 shown in
A Luer lock valve 24 is associated with a squeezable air or liquid bulb 27 in communication with the air/liquid passageway 14 and is initially filled with water. When it is squeezed it forces either air liquid through the combination air/liquid passageway 14 to inflate the balloon positioning tip 18. When it contracts, liquid is drawn back into its internal reservoir 27.
A second squeezable air bulb 27 is then interchanged with the liquid filled bulb 27 in communication with the air/liquid passageway 25 and 14 to inject air to inflate the positioning tip 18. The Luer Lock valve 24 mechanism manufactured by many manufacturers facilitates this interchange. Although their appearance may vary, the principle of operation is the same. The technician using same can either inject air or water. This can be accomplished by squeezing the internal reservoir 27 for water to inflate the positioning tip 18. By replacing the internal liquid filled reservoir 27 with a second air filled reservoir 27, thereby draining the system of water, the positioning tip 28 is then inflated with air. A syringe type adaptor using the valve 24 may also be used for this purpose to inflate the positioning tip 18. Inflation of the positioning tip is critical.
The inflated positioning tip 18 assists in securing the stent 22 in the right position proximate the bladder neck. The air filled positioning tip 18 creates a different media thickness that is easily detected by ultrasound equipment. This allows a doctor to place the stent 22 precisely without the use of a fluoroscope. As every urologist has access to ultrasound in his office, if the position of the stent 22 is questionable, it may be located with ultrasound and repositioned, if necessary. Water can be replaced with air entering the air/liquid passageway 14 via the Luer lock valve 24 to inflate the positioning tip 18 with air, which will show up much easier on the ultrasound than water. This gives more accurate confirmation of the positioning tip 18 and stent 22 location. The doctor therefore does not have to resort to another facility to perform the procedure using fluoroscopes.
In cases where the urethra is severely obstructed, it may require a stent 22, which is better held by the securing end 16 during positioning.
When stent 22 is in the desired location Luer lock valve 24, is then set for air injection and is squeezed. Squeezing the Luer lock valve 24 forces air through the air/liquid passageway 16 inflating the positioning tip 18 for ultrasound positioning. Pressing Luer lock valve 24 again releases the air pressure and deflates the positioning tip 18 for easy removal of the stent inserter 10.
It is estimated that this device will provide relief for over 65% of the patients with urination difficulties, which require frequent trips to the bathroom to empty the bladder. The fact that this can be accomplished in a urologist's office without having to go to an emergency room out patient clinic saves expense, and better serves patient's needs.
Although this specification has referred to the specific embodiments, it is not intended to restrict the scope of the claims. The scope of the invention is, therefore, indicated by the appended claims, rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.
