News Column

Patent Issued for Drug Eluting Vascular Closure Devices and Methods

June 27, 2014



By a News Reporter-Staff News Editor at Drug Week -- From Alexandria, Virginia, NewsRx journalists report that a patent by the inventor Yassinzadeh, Zia (San Jose, CA), filed on February 23, 2010, was published online on June 10, 2014 (see also Cardiva Medical, Inc.).

The patent's assignee for patent number 8747435 is Cardiva Medical, Inc. (Sunnyvale, CA).

News editors obtained the following quote from the background information supplied by the inventors: "The present invention relates generally to devices and methods for percutaneous sealing of puncture sites in body lumens or tissue tracts. More specifically, the present invention relates to drug eluting vascular closure devices and methods for hemostasis of vascular puncture sites.

"Percutaneous access of blood vessels in the human body is routinely performed for diagnostics or interventional procedures such as coronary and peripheral angiography, angioplasty, atherectomies, placement of vascular stents, coronary retroperfusion and retroinfusion, cerebral angiograms, treatment of strokes, cerebral aneurysms, and the like. Patients undergoing these procedures are often treated with anti-coagulants such as heparin, thrombolytics, and the like, which make the closure and hemostasis process of the puncture site in the vessel wall at the completion of such interventional procedures more difficult to achieve.

"Various devices have been introduced to provide hemostasis, however none have been entirely successful. Some devices utilize collagen or other biological plugs to seal the puncture site. Alternatively, sutures and/or staples have also been applied to close the puncture site. External foreign objects such as plugs, sutures, or staples however may cause tissue reaction, inflammation, and/or infection as they all 'leave something behind' to achieve hemostasis.

"There is also another class of devices that use the body's own natural mechanism to achieve hemostasis wherein no foreign objects are left behind. Such devices typically provide hemostasis by sealing the puncture site from the inside of the vessel wall wherein the device is left in place in the vessel lumen until hemostasis is reached and thereafter removed. Although such safe and simple devices have achieved relative levels of success, they often are slow in achieving complete hemostasis, particularly in highly anti-coagulated patients. As such, such devices are often used as an adjunct to manual compression which still remains to be the most used method in closing the puncture site after the interventional procedure.

"There is yet another class of devices where highly thrombogenic substances are mixed and injected to the puncture site for the purpose of accelerating the hemostatic process. These mixtures contain one or more clot promoting substances, such as thrombin and/or fibrinogen, along with other substances, such as collagen. These devices generally work by first occluding the puncture site from the inside of the vessel, usually by use of a balloon, and then injecting the mixture into the tissue tract. The balloon is then removed. Such devices suffer from several drawbacks which may cause severe complications. For example, the occluding member may not be adequate to prevent these highly thrombogenic substances from entering the blood vessel. Further, the injection of the mixture is often not well controlled and highly technique dependant, which again may allow these substances to enter the blood stream.

"In light of the above, it would be desirable to provide alternative devices and methods for providing complete hemostasis of a puncture site in a body lumen, particularly blood vessels of the human body. It would be particularly desirable if such devices and methods utilize the body's own natural healing mechanism to achieve hemostasis. It would be further desirable if the natural hemostatic process can be safely accelerated by the controlled use of bio-chemical agents. It would be further desirable if such devices and systems utilize a simple construction and user interface allowing for convenient application without numerous intermediary steps. Further, such devices should be safe and reliable without the need for much user intervention. At least some of these objective will be met by the devices and methods of the present invention described hereinafter.

"Hemostasis devices for use in blood vessels and tracts in the body are described in pending U.S. patent application Ser. Nos. 10/974,008; 10/857,177; 10/821,633; 10/795,019; and 10/718,504 and U.S. Pat. Nos. 6,656,207; 6,464,712; 6,056,770; 6,056,769; 6,045,570; 6,022,361; 5,951,589; 5,922,009; and 5,782,860, assigned to the assignee of the present application. The following U.S. Patents and Publications may be relevant to the present invention: U.S. Pat. Nos. 4,744,364; 4,852,568; 4,890,612; 5,108,421; 5,171,259; 5,258,000; 5,383,896; 5,419,765; 5,454,833; 5,626,601; 5,630,833; 5,634,936; 5,728,134; 5,836,913; 5,861,003; 5,868,778; 5,951,583; 5,957,952; 6,017,359; 6,048,358; and 6,296,657; U.S. Publication Nos. 2002/0133123; 2003/0055454; 2003/0045835; and 2004/0243052.

"The full disclosures of each of the above mentioned references are incorporated herein by reference."

As a supplement to the background information on this patent, NewsRx correspondents also obtained the inventor's summary information for this patent: "The present invention provides drug eluting, self-tensioning closure devices and methods for percutaneous access and closure of puncture sites in a body lumen, particularly blood vessels of the human body. It will be appreciated however that application of the present invention is not limited to the blood vasculature, and as such may be applied to any of the vessels, even severely tortuous vessels, ducts, and cavities found in the body as well as tissue tracts. Such closure devices and methods utilize the body's own natural healing mechanism to achieve hemostasis. This natural hemostatic process is further accelerated by the integration of bio-chemical agents or means for delivering such agents.

"In a first aspect of this invention, a device for closing a blood vessel puncture site disposed at a distal end of a tissue tract comprises a shaft having a proximal end and a distal end, an expansible member, a bio-chemical sealing member, and a bio-chemical region or release region. The shaft is configured to advance through the tissue tract while the expansible member disposed on the distal end of the shaft is deployable within the blood vessel. The bio-chemical sealing member is slidably disposed over the shaft and proximal the expansible member. The bio-chemical region or release region is disposed under the sealing member. Advantageously, displacement of the bio-chemical sealing member in a proximal direction exposes the region so as to allow for safe and controlled release of bio-chemical agents into the tissue tract for enhanced and complete hemostasis of the puncture site.

"The bio-chemical sealing member prevents severe complications as a result of bio-chemical agents from coming in contact with the blood stream by only allowing for the controlled exposure of such agents in the tissue tract. The sealing member has a length in a range from about 0.1 cm to about 100 cm, typically from about 5 cm to about 20 cm and a diameter in a range from about 0.5 mm to about 5 mm, typically from about 1 mm to about 3 mm. The sealing member may be a tubular member formed from a variety of medical grade materials, including coiled stainless steel tubing or polymer materials such as nylon, polyurethane, polyimide, PEEK.RTM., PEBAX.RTM., and the like.

"In a preferred embodiment of the device, a tensioning element, such as a spring or coil, is further provided. The tensioning element is slidably disposed over the shaft and under the sealing member proximal the expansible member. Generally, during application of the device, the tensioning element is preferably positionable in the tissue tract, but in other instances may be outside the tissue tract. The tensioning element gauges how much tension is being applied to the expansible member as it is seated against the puncture site so as to prevent a user from applying excessive force on the device causing undesirable movement (e.g., device is pulled out of patient body). The tensioning element also provides device compliance in cases of patient movement while the device is in place. The expansible member allows for sealing of the puncture site while the tensioning element along with an external clip apply and maintain tension to the expansible occluder so that it is seated against the puncture site at a vascular surface (e.g., blood vessel wall).

"Positioning the expansible member against the vessel wall positions the bio-chemical region or release region outside the vessel lumen at a predetermined distance from the vessel wall and proximal the expansible member. Therefore, the expansible member provides not only occlusion at the vessel puncture site but also functions as a locator so as to position the bio-chemical region or release region outside the vessel lumen. This in turn ensures safe release of bio-chemical agents in the tissue tract and outside the blood stream. The predetermined distance is in a range from about 0 to about 20 mm, typically in a range from about 2 mm to about 10 mm.

"The bio-chemical region or release region has a length in a range from about 1 mm to about 100 mm, typically in a range from about 5 mm to about 50 mm. It will be appreciated that the length and/or volume of the region may be varied in order to integrate and release the desired amount of bio-chemical agent. In one embodiment, the bio-chemical region includes at least one bio-chemical agent disposed on the distal end of the shaft proximal the expansible member and distal the tensioning element. In another embodiment, the region includes at least one bio-chemical agent disposed on the tensioning element. The agents may be coated, sprayed, molded, dipped, vapor deposited, plasma deposited, or painted thereon. Such a bio-chemical region on the occlusion device itself further minimizes variations due to user techniques, which may be particularly problematic with injection protocols where such agents are injected into the tract by the user. In yet another embodiment, the device may further incorporate an expansible feature disposed on the distal end of the shaft proximal the expansible member, wherein the region includes at least one bio-chemical agent associated with the expansible feature.

"In alternative embodiments of the present invention, the device may further incorporate at least one bio-chemical delivery conduit disposed over the shaft and under the tensioning element and a bio-chemical injection port in fluid communication with the delivery conduit. The injection port may be connected to a syringe by use of a compression fitting or with an integrated luer lock. The bio-chemical agents are injected into the device via the syringe once the device is properly positioned. It will be appreciated that the size of the injection port and the delivery conduit may be selected to control the delivery rate of such agents. In one example, the release region includes at least one opening, aperture, or orifice in fluid communication with a distal end of the conduit proximal the expansible member. It will be appreciated that any number, size, and/or shape of opening(s) may be utilized in order to obtain the desired release rate of bio-chemical agent. The release region may incorporate about 1 opening to about 100 openings, typically about 1 opening to about 10 openings. In another example, the release region includes at least one porous member in fluid communication with a distal end of the conduit proximal the expansible member so as to allow for the desired release of the bio-chemical agent.

"A controlled delivery rate allows the bio-chemical agents to 'ooze' out of the release region. This may eliminate the potential of high pressure release, which in turn minimizes the possibility of these agents from entering the blood stream. In addition, the sealing member serves to cover the bio-chemical release region so as to prevent any blood from flowing back through the release region, through the delivery conduit, and out through the injection port. The sealing member is only slidably displaced, revealing the bio-chemical release region, when it is desirable to deliver the bio-chemical agents.

"The device of the present invention may further incorporate a spacer element disposed between the sealing member and the tensioning element so that the sealing member may easily slide over the tensioning element. The spacer element may be a tubular member formed from a variety of materials, including tubular polymer materials such as nylon, polyurethane, polyimide, PEEK.RTM., PEBAX.RTM., and the like. The device further includes a handle on a proximal end of the shaft. A safety tab may be disposed between the handle and the sealing member. The safety tab prevents any undesirable displacement of the sealing member so as to inhibit inadvertent release of bio-chemical agents.

"The present invention integrates the expansible member, bio-chemical sealing member, bio-chemical region or release region, and tensioning element in a single unitary catheter construction. This simple construction and user interface allows for safe, easy and convenient application of the device without numerous intermediary steps. The sealing member in combination with the locating expansible member ensures that the bio-chemical region or release region is only exposed in the tissue tract. This results in a more reliable, safe, and effective device which provides immediate and complete hemostasis, which in turn reduces the risk of bleeding, hematoma formation, thrombosis, embolization, and/or infection.

"In another aspect of the present invention, methods for hemostasis of a puncture site in a blood vessel at a distal end of a tissue tract are provided. One method comprises introducing any one of the closure devices as described herein through the tissue tract. The expansible member is deployed at a distal end of the device within the blood vessel. The bio-chemical sealing member disposed proximal the expansible member is then displaced once properly positioned so as to expose a bio-chemical region or release region of the device. At least one bio-chemical agent is then released from the device and into the tissue tract.

"The sealing member is displaced in a proximal direction so as to expose at least a portion of the region. This displacement distance is in a range from about 0.1 cm to about 10 cm, typically from about 0.5 cm to about 5 cm. The method further comprises deploying the tensioning element disposed proximal the expansible member within the tissue tract so that the expansible member is seated against a puncture site. Typically, deploying the tensioning element and displacing the sealing member is carried out simultaneously so as to provide for easy and convenient application of the device without numerous intermediary steps. However, it will be appreciated that deployment of the tensioning element may be carried out independently, typically prior to displacement of the sealing member, so as to provide for proper positioning of the region or release region within the tissue tract and closure of the puncture site.

"The amount of tension applied to the expansible member by the tensioning coil or spring is in the range from about 0.5 ounce to 30 ounces, typically in a range from about 2 ounces to 10 ounces. As described above, the expansible member locates and closes the puncture site in the blood vessel wall. Coil elongation is sufficient to provide adequate amount of tension on the expansible member to temporary seal the puncture and to adequately displace the sealing member to reveal the bio-chemical region or release region. In some embodiments, coil elongation may be limited by a coupling member. Generally the amount of elongation of the tensioning coil may be the same as for displacement of the sealing member. The tension provided by the tensioning coil and the exposure of the bio-chemical agents may be maintained by application of an external clip on the tensioning coil, generally over the sealing member, wherein the clip rests over the skin at the puncture site.

"Bio-chemical agent release generally comprises positioning the region at a predetermined distance proximal to the expansible member and outside the blood vessel wall. In particular, increasing the tension in the coil positions the expansible member against the puncture site and locates the bio-chemical region or release region in the tissue tract at the predetermined distance. Further increase in tension will cause the sealing member to disengage from an attachment point at the proximal end of the expansible member and the tensioning coil to elongate. Elongation of the tensioning coil will result in the sealing member to slide proximally so as to expose the region to the surrounding tissue for release of the bio-chemical agent.

"The bio-chemical agents may accelerate the coagulation process and promote the formation of coagulum at the puncture site so to achieve complete hemostasis. The bio-chemical agent may comprise a variety of agents including clot promoting agents (e.g., thrombin, fibrinogen, etc.) or vaso-constricting agents (e.g., epinephrine, etc.). The bio-chemical agent is released for a time period in the range from about 0.1 minute to about 15 minutes, typically from about 0.5 minute to about 5 minutes. As described above, the occlusion device may be modified in several ways (e.g., region length, region volume, release region openings, conduit dimensions, number of conduits, or port dimensions) to achieve the desired bio-chemical agent release characteristics (e.g., rate, amount, time, etc.). The methods of the present invention may involve re-hydrating the bio-chemical agent with fluid in the tissue tract so as to generate coagulum. These agents may use the blood components to form a coagulum even at the presence of anti-coagulants.

"As described above, the bio-chemical agent may be coated, sprayed, molded, painted, dipped, or deposited at the region. Alternatively, bio-chemical agents may be injected in a delivery conduit in fluid communication with at least one opening disposed at the release region. The sealing member in such an embodiment further prevents any blood from flowing back through the openings of the release region prior to placing the expansible member against the vessel wall when the release region is in the vessel lumen. Injection of bio-chemical agents in the presence of blood in the bio-chemical delivery pathway may cause undesirable coagulum to form in the pathway which could prevent the bio-chemical agents from reaching the target site.

"A further understanding of the nature and advantages of the present invention will become apparent by reference to the remaining portions of the specification and drawings."

For additional information on this patent, see: Yassinzadeh, Zia. Drug Eluting Vascular Closure Devices and Methods. U.S. Patent Number 8747435, filed February 23, 2010, and published online on June 10, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8747435.PN.&OS=PN/8747435RS=PN/8747435

Keywords for this news article include: Legal Issues, Cardiva Medical Inc..

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Source: Drug Week


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