Patent Application
20110066226
The present invention relates to an intravascular device for treatment of erectile dysfunction. More particularly, the intravascular device is a venous valve that may be implanted in a penile vein to selectively restrict blood outflow through the penile vein in order to achieve and/or maintain an erection.
The National Institutes of Health estimates that 30 million American men suffer from mild, moderate or complete erectile dysfunction. Erectile dysfunction is the chronic, i.e., greater than three months duration, inability to maintain a penile erection for satisfactory sexual intercourse.
There are both psychological and physical causes of erectile dysfunction. Most causes of erectile dysfunction have an adverse effect on nerves and/or blood vessels to, from, and within the penis. Vascular disease is considered a leading physical cause of erectile dysfunction with atherosclerosis of the penile arteries alone accounting for about 40% of patients over 40 years of age with erectile dysfunction. Other possible vascular-related causes include diabetes, hypertension, high cholesterol, renal disease, and smoking.
Essentially, penile erection occurs when the two corpora cavernosa fill with blood and maintain pressure adequate for penetration. Each corpus cavernosum is fed by a deep artery of the penis located in the center of each cavernosum. Each deep artery has many smaller coil-shaped arteries, called helicine arteries extending downstream therefrom that open directly into the corpora cavernosa. Erection of the penis is a parasympathetic nervous system process that effects the release of neurotransmitters, which allows the relaxation of smooth muscle fibers surrounding the helicine arteries resulting in an increase in arterial inflow in the corpora cavernosa. Blood then fills these erectile compartments, and in the process compresses the penile veins that drain these tissues. The obstruction of venous flow is as important in obtaining and maintaining an erection as is an adequate arterial blood supply. The net effect of this increased inflow and decreased blood outflow is to raise the pressure of the corpora cavernosa to approximately the mean arterial pressure of the cavernosal artery, which in a normal patient is approximately 100 mm Hg. Subsequent activation of the sympathetic nervous system returns the penis to a flaccid state. With reference to
In cases where erectile dysfunction occurs due to, or is complicated by venous leakage there are various bands, rings and ligatures that have been suggested to restrict blood flow leaving the penis and thereby enable a patient to achieve an erection. Some such restrictive devices are externally secured around the base of the penis and are worn only during sexual activity, whereas others are surgically or laparoscopically implanted and are externally activated to temporarily contract around penile tissue or exit veins of the penis to enable the erection. A binary duct valve has also been suggested for use in penile veins to selectively induce tumescence. The binary duct valve is implanted surgically or via a needle puncture into the vein and includes a ball valve of a magnetic material that is operated extracorporeally by a user manipulating a magnet. Each of the afore-mentioned apparatuses for treating erectile dysfunction that is caused or aggravated by venous leakage suffers from disadvantages, some of which are addressed by a venous valve according to the present invention.
Embodiments hereof are directed to an implantable venous valve for selectively restricting the outflow of blood from a penile vein to aid a user in achieving and/or maintaining an erection. The venous valve includes a self-expanding stent framework defining a blood flow lumen therethrough. The self-expanding stent framework is constructed to recoil from a radially compressed configuration in which the blood flow lumen is narrowed to restrict blood flow through the venous valve to a radially expanded configuration in which the blood flow lumen is fully open to permit unrestricted blood flow through the venous valve. A recoil delay component is attached to the self-expanding stent framework for slowing the recoil of the self-expanding stent framework and thereby provides an extended time period during which the blood flow lumen is narrowed such that blood flow through the venous valve is restricted.
Embodiments hereof are also directed to methods of using a venous valve for selectively restricting the outflow of blood from a penile vein to aid in achieving and/or maintaining an erection. The methods include implanting a venous valve into a penile vein at a target location that is susceptible to a compressive radial force exerted on the penis. A venous valve for use in methods hereof includes a self-expanding stent framework defining a blood flow lumen there through and a recoil delay component attached to the self-expanding stent framework that delays the recoil of the self-expanding stent framework from a radial compressed configuration to a radially expanded configuration. The methods further include firmly pressing on the penis to impart a compressive radial force on the venous valve implanted at the target location thereby radially compressing the self-expanding stent framework and initiating an extended time period during which the blood flow lumen is narrowed to restrict blood outflow from the penile vein.
The foregoing and other features and advantages of the invention will be apparent from the following description of embodiments thereof as illustrated in the accompanying drawings. The accompanying drawings, which are incorporated herein and form a part of the specification, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention. The drawings are not to scale.
Specific embodiments of the present invention are now described with reference to the figures, wherein like reference numbers indicate identical or functionally similar elements. The terms “distal” and “proximal” are used in the following description with respect to a position or direction relative to the treating clinician. “Distal” or “distally” are a position distant from or in a direction away from the clinician. “Proximal” and “proximally” are a position near or in a direction toward the clinician.
The following detailed description is merely exemplary in nature and is not intended to limit the invention or the clinical application and uses of the invention. Although the description of the invention is in the context of placement within a blood vessel such as the superficial and deep dorsal veins, the invention may also be used in any other body passageways where it is deemed useful. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following
Stent framework 206 is an exemplary stent framework in accordance with an embodiment of the present invention that is made self-expanding by virtue of the internal restoring forces of the spring-type or superelastic material selected for its construction. In an embodiment hereof, stent framework 206 is formed of a pseudoelastic or stress induced martensitic (SIM) alloy of nickel-titanium (nitinol). Stent framework 206 is a patterned tubular device that includes a plurality of radially expandable cylindrical rings 216. Cylindrical rings 216 are formed from struts 218 having a generally sinusoidal pattern that includes peaks 220, valleys 222, and generally straight segments 224 connecting peaks 220 and valleys 222. Connecting links 226 connect adjacent cylindrical rings 216 together. In
The superelastic or pseudoelastic material selected for forming self-expanding stent framework 206 permits venous valve 204 to recoil or recover from a radially compressed configuration in which blood flow lumen 208 is narrowed, as shown in
The recoil or recovery of stent framework 206 alone, i.e., without recoil delay component 214 attached thereto, from a radially compressed configuration to a radially expanded configuration conventionally occurs immediately upon removal of the external force causing the compression, which means that stent framework 206 conventionally will quickly or over a short time period such as 0.1-1.0 seconds, return to its radially expanded configuration. In order to slow or delay the recoil of self-expanding stent framework 206 after release of an external force in accordance with an embodiment hereof, recoil delay component 214 is coupled to self-expanding stent framework 206 to increase or extend a time period after release of an external force during which venous valve 204 is in a radially compressed configuration and blood flow lumen 208 is narrowed or flattened. Recoil delay component 214 is formed of a viscoelastic polymeric material having a thickness of 0.1-1.0 mm that exhibits slow elastic recovery in order to impart a damping effect on self-expanding stent framework 206 and that is biostable such that recoil delay component 214 will not biodegrade or bioabsorb during prolonged implantation in vivo. In another embodiment, recoil delay component 214 may be formed of a biostable elastomeric material, such as biostable polyurethane elastomers or silicone foams. The damping effect of recoil delay component 214 is expected to inhibit or delay the internal restoring forces of stent framework 206 from quickly returning venous valve 204 to a radially expanded configuration upon release of an external force. The viscoelastic polymeric material selected for recoil delay component 214 undergoes time dependent strain and therefore takes a longer period of time to elastically recover from an applied external force than does self-expanding stent framework 206 formed from a superelastic material.
In an embodiment, recoil delay component 214 should sufficiently slow the recovery of stent framework 206 from the radially compressed configuration such that blood flow lumen 208 of venous valve 204 will be narrowed or closed for a time period of between 20 to 60 minutes. When venous valve 204 is positioned in vivo within a penile vein, such as the deep dorsal vein or the superficial dorsal vein as further discussed below, blood flow through venous valve 204 may be restricted for 20 to 60 minutes so that outflow of blood from the penile vein is diminished for this time period thereby aiding the user in achieving and/or maintaining an erection. The end of the restricted time period may be defined as the time at which venous valve 204 has completely reverted to the radially expanded configuration shown in
Viscoelastic polymeric materials that may be adapted for use in forming recoil delay components in accordance with embodiments hereof include but are not limited to foam rubber such as foam polyurethane sold under the trademark PPT and available from Langer Biomechanics, Deer Park, N.Y., and thermoset polyether-based polyurethane material sold under the trademark SORBOTHANE, available from Sorbothane, Inc. of Kent, Ohio, and acrylate polymer sold under the trademark 3M Viscoelastic Damping Polymer 242NR02 available from 3M Corporation of St. Paul, Minn. As well, viscoelastic polymeric gels, thermoset polyurethane gels, cohesive polymeric silicone gels sold under trademarks MEMORY GEL and COHESIL available from Mentor Corporation, Santa Barbara, Calif., and slow elastic recovery hydrogels, such as hydrogels disclosed in U.S. Pat. No. 4,452,776 to Refojo which is incorporated by reference herein in its entirety, may be adapted for use in embodiments hereof.
In the embodiment of venous valve 204 shown in
Recoil delay component 314 of venous valve 304 may be formed of any of the slow elastic recovery materials disclosed above with reference to recoil delay component 214 and may have a thickness of 0.1-1.0 mm in order to impart a damping effect on intermediate section 330 of self-expanding stent framework 306. The damping effect of recoil delay component 314 inhibits or delays the internal restoring forces of intermediate section 330 of stent framework 306 from quickly returning that portion of venous valve 304 from a radially compressed configuration to a radially expanded configuration upon release of an external force causing the compression. The delayed recoil of intermediate section 330 of venous valve 304 is expected to provide a time period during which blood flow lumen 308 is narrowed or closed and blood flow through venous valve 304 is restricted, such as a time period of between 20 and 60 minutes.
Recoil delay component 414 of venous valve 404 may be formed of any of the slow elastic recovery materials disclosed above with reference to recoil delay component 214 and may have a thickness of 0.1-1.0 mm in order to impart a damping effect on self-expanding stent framework 406. The damping effect of recoil delay component 414 inhibits or delays the internal restoring forces of stent framework 406 from quickly returning venous valve 404 from a radially compressed configuration to a radially expanded configuration upon release of an external force causing the compression. The delayed recoil of venous valve 404 is expected to provide a time period during which blood flow lumen 408 is narrowed or closed and blood flow through venous valve 404 is restricted, such as a time period of between 20 and 60 minutes.
With reference to
Catheter-based delivery system 750 includes an inner shaft 755 having venous valve 504 mounted around a distal end 760 thereof, and a retractable outer sheath 765 that covers and constrains venous valve 504 in a reduced diameter while delivery system 750 is tracked through a vessel to the delivery site. The operation and structure of catheter-based delivery system 750 is more fully described in U.S. Pat. No. 6,126,685 to Lenker et al., which is incorporated by reference herein in its entirety. In other embodiments, delivery systems that are well known in the art may be used to deliver implantable venous valves in accordance herewith. In embodiments hereof, the delivery site for the venous valve may be within deep dorsal vein 100 or superficial dorsal vein 102 at a location near the base of the penis proximate the point where the penile vein enters the torso. The venous valve is intended to be positioned such that it may be radially compressed within the penile vein by a user pressing firmly on the base of the penis, as discussed further below with reference to the embodiment shown in
As prophetically illustrated in
Another means for keeping the venous valve 504 at the target location is shown in
In an embodiment shown prophetically in
Another method of delivering a venous valve in accordance with embodiments hereof may include identifying a target penile vein via ultrasound or color Doppler imaging and gaining access to the penile vein by performing a micropuncture procedure on the penis with a cannula. The venous valve may then be deployed within the penile vein through the cannula.
After initial deployment within the target penile vein, a venous valve in accordance with embodiments hereof is expected to become attached to or embedded within the penile vein due to endothelialization that occurs as cells grow around the stent framework of the venous valve. Implantable venous valves in accordance with embodiments hereof must be sufficiently endothelialized in order to prevent dislodgment from the penile vein when radially compressed and in order to “pull” the walls of the vein inward upon being radially compressed to stop or restrict the blood flow there through. Full endothelialization of venous valves in accordance herewith may occur as quickly as three weeks or may take up to eight weeks. In order to allow endothelialization of the venous valve, each of the embodiments of
Penile vein 500 extends within the pendant portion of the penis and is susceptible to finger pressure exerted on the penis by the user, and accordingly may be one of the superficial or deep dorsal veins of the penis. As noted above, venous valve 504 is intended to be positioned at a location along penile vein 500 such that venous valve 504 may be radially compressed within penile vein 500 by a user pressing firmly on or near the base of the penis, i.e., the portion of the penis that is positioned external or outside of the pubic bone and the urogenital diaphragm. In conjunction with the normal parasympathetic nervous system processes associated with arousal, venous valve 504 may be selectively compressed by a user whenever an erection is desired to be attained or maintained. As such, recoil delay component 514 is expected to be capable of repeated/numerous uses over the lifetime of the user in delaying the recoil of stent framework 506 after being subjected to compressions of venous valve 504.
While various embodiments according to the present invention have been described above, it should be understood that they have been presented by way of illustration and example only, and not limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the appended claims and their equivalents. It will also be understood that each feature of each embodiment discussed herein, and of each reference cited herein, can be used in combination with the features of any other embodiment. All patents and publications discussed herein are incorporated by reference herein in their entirety.
