Patent Application
20090187147
1. Field of the Invention
The invention relates to the field of micropuncture endovascular devices and methods, and in particular to micropuncture endovascular systems and guidewires for vascular introduction and methods of using the same.
2. Description of the Prior Art
The prior art methodology used to make a micropuncture is as follows: (1) First the vasculature is punctured with a microneedle. (2)Then placement of a microguidewire through the needle is achieved. (3)Then a coaxial catheter pair is advanced over the microguidewire into the blood vessel. (4) Then the microguidewire is removed and then (5) The inner sleeve of the coaxial catheter pair is removed and discarded. (6) Then a large guidewire is introduced into the vasculature through the remaining outer sleeve (which has an inside diameter large enough to accommodate a large guidewire) of the coaxial catheter pair, (7) Then the retained outer sleeve must be removed. Then the larger introducer or medical device is advanced over the larger guidewire. Seven steps and two guidewires are currently required to place a large guidewire using the micropuncture technique.
The prior art systems require the introduction of two separate guidewires into the vasculature. Each time a guidewire is introduced it carries the risk of damaging the lining of the blood vessel which may result in thrombosis and tissue or organ damage. The prior art systems also require a pair of coaxial catheters to be used in order to deploy a larger diameter guidewire, significantly adding to the number of components and steps required for placement of a large guidewire. The current systems for micropuncture guidewire placement are thus unnecessarily complex and potentially dangerous to the patient.
What is needed is a system that allows for a micropuncture to be achieved while minimizing the risk to the patient. This is achieved by using a (1) removable needle or sleeve for the micropuncture and (2) placing only one guidewire as apposed to two. The invention not only reduces the risk of trauma to the patient's tissues and vasculature but also reduces the number of components and steps required for the overall procedure. Placement of a large guidewire is reduced to placing one guidewire using only two to three procedural steps.
The illustrated embodiment of the invention is an apparatus and method of using an assembly comprising a longitudinally openable or separable, small diameter, hollow micropuncture device or microneedle for puncture into a vascular or body cavity while minimizing tissue trauma at a puncture site, and a stepped guidewire. The term, “micropuncture device”, shall be used throughout this specification and claims to refer to a needle, microneedle, and/or an assembly of elements which include a microneedle, a needle or an element that functions at least in part as a microneedle or needle having a maximum gauge size of 20, or can accommodate a 0.025 inch maximum sized diameter guidewire. The terms, “non-micropuncture vascular device”, “larger diameter vascular instrument”, “larger medical device”, “large instrument” are defined as a vascular or medical instrument which is too stiff or too large in diameter to be effectively or reliably guided into the vascular system or other body cavity through a micropuncture device or by means of guidewires which are usable in micropuncture devices. The term “microguidewire” refers to a guidewire or a portion of a guidewire that is 0.025 inch diameter or smaller whereas the term “larger guidewire” refers to a guidewire or a portion of a guidewire that is larger than 0.025 inch diameter. The micropuncture device has an inner diameter; and the stepped guidewire has a distal portion for telescopic disposition through the inner diameter of the micropuncture device or needle, and a proximal portion with a diameter larger than the inner diameter of the micropuncture device or needle. The stepped guidewire is provided for guiding a larger diameter vascular instrument. By use of the illustrated embodiment tissue trauma at the puncture site is substantially reduced.
The illustrated embodiment of the invention is thus a method comprising the steps of inserting a microneedle into a body cavity to achieve a micropuncture into the cavity while minimizing tissue trauma at a puncture site. A stepped guidewire, a tapered guidewire, or a two part guidewire such as comprised of a core guidewire and a catheter, or a core guidewire and a coil, where the guidewire has a reduced diameter distal portion, is telescopically disposed through the inner diameter of the microneedle. A proximal portion of the guidewire has a diameter larger than the inner diameter of the microneedle and extends to a proximal end of the guidewire. The proximal portion is adapted for guiding a larger diameter instrument into and through the vascular system. The microneedle is withdrawn from the micropuncture while leaving the distal portion of the guidewire extending through the micropuncture. The microneedle is removed from the guidewire without removing the microneedle over the proximal end of the guidewire. As a result, tissue trauma at the puncture site is substantially reduced.
The illustrated embodiment of the method further comprises the steps of advancing the guidewire into the micropuncture to extend the proximal portion of the guidewire through the micropuncture, and guiding a large diameter instrument over the guidewire through the micropuncture using the proximal portion as a guiding guidewire.
Another embodiment of the method further comprises the steps of advancing the guidewire into the micropuncture to extend only the distal portion of the guidewire through the micropuncture, and guiding a larger diameter instrument telescopically over the guidewire through the micropuncture using the distal portion as a guiding guidewire only through the micropuncture.
In one embodiment the method further comprises the step of advancing the guidewire to extend the proximal portion of the guidewire through the larger diameter instrument in the micropuncture and then into the body cavity to provide a guiding guidewire for the larger diameter instrument to a target site in the body cavity.
The step of separating and removing the micropuncture device or needle comprises longitudinally opening, separating, tearing, splitting, peeling, or otherwise removing the micropuncture device or needle along a slotted section, or section line or lines or a score line or lines, or through a weak material, or a material of molecular orientation defined into or on the micropuncture device or needle. For the purposes of this specification, if an element is termed to be “separable”, it is then capable of being opened, separated or separated from something, torn, split, peeled, taken away from something or otherwise removed.
In one embodiment the body cavity comprises a vascular cavity, and the step of inserting a microneedle into a body cavity comprises steps of making a transdermal micropuncture into a vascular cavity.
The illustrated embodiment of the invention is also an apparatus comprising a longitudinally separable, small diameter, hollow micropuncture device or microneedle for puncture into a vascular cavity while minimizing tissue trauma at a puncture site caused by the puncture device. The micropuncture device has an inner diameter. A stepped or tapered guidewire has a distal portion for telescopic disposition through the inner diameter of the micropuncture device, and a proximal portion having a diameter larger than the inner diameter of the micropuncture device and for guiding a larger diameter vascular instrument. As a result tissue trauma at the puncture site is substantially reduced.
In another embodiment the micropuncture device comprises a micropuncture needle, and an openable or separable sleeve mounted over the needle. The micropuncture device then punctures the body cavity or vasculature and deposits or introduces the openable or separable sleeve in the body cavity. The inner puncturing needle is then removed from the outer sleeve. The microguidewire is then passed through the retained or implanted sleeve until the larger diameter of the proximal portion of the guidewire abuts against the smaller inside diameter of the retained sleeve. The sleeve is then opened or removed from the guidewire by separating, tearing, peeling, splitting or any other means now known or devised in the future. The proximal portion of the guidewire can then be advanced through the micropuncture.
In another embodiment, the needle is slotted or split into two portions, but sealed by a thin shrink wrapped or compressed separable sleeve or tube. A hub attached to the needle may also be similarly slotted or split and sealed by the sleeve. The needle is then opened or separated in the above procedure along the slot or split by tearing or separating the sleeve, which preferably encases the exterior of the needle.
The term “sleeve” is used throughout this specification and refers to a material that can be separated to allow removal of the micropuncture device. The sleeve may embody the entire circumference or diameter, or just cover a small portion of the circumference or diameter so as to provide a seal to minimize the passage of fluid. The sleeve can be in the form of a sealant, gel, film, glue, membrane, extrusion, balloon, or any other means that enables removal of the micropuncture device from the guidewire without removing the micropuncture device over the proximal potion of the guidewire.
In one embodiment the distal portion of the guidewire has a diameter of approximately 0.018-0.021 inch and where the proximal portion has a diameter of approximately 0.035-0.038 inch.
The distal portion is characterized as a microguidewire having a diameter such that penetration of the distal portion into tissue and disposition into a vascular cavity reduces tissue trauma.
The apparatus is used in combination with a larger diameter instrument and the proximal portion of the guidewire is characterized as suitable for providing a guiding force to the larger diameter medical instrument which is telescopically disposed over the proximal portion.
The distal portion is chosen with a size of diameter so that it is extremely flexible and atraumatic but is not optimally configured for guiding a larger medical instrument through the vasculature.
The proximal portion of the guidewire has a diameter such that it guides and steers a larger medical instrument in the vascular system.
The distal portion is preferably about 30 cm long and the length of the proximal portion is preferably about 30 cm but the lengths can be adjusted depending on the length of the micropuncture device or needle and the length of the medical instrument that needs to be introduced into the vasculature.
The transition between the proximal and distal portions of the guidewire may be a sharp step. The transition between the proximal and distal portions may be a gradual taper whose longitudinal length is ten diameters of the proximal portion or more. Less steep tapers or a more gradual step are also contemplated within the scope of the invention.
In yet another characterization of the illustrated embodiment of the invention, it is defined as an apparatus for use in introducing a medical instrument into a vascular system comprising a separable means for producing a micropuncture into the vasculature while reducing tissue trauma at a puncture site, and a first means for maintaining access through the puncture site into the vascular system while reducing tissue trauma. The first means for maintaining access is telescopically disposed within the separable means for producing the micropuncture. A second means is provided for guiding the medical instrument within the vascular system. The second means is disposed into the vascular system through the micropuncture after the separable means is separated and removed from the first means for maintaining access.
The first means guides the medical instrument only through the puncture site and a predefined distance into the vascular system.
The separable means comprises a micropuncture device or microneedle with a longitudinal section line or lines or score line or lines along which the micropuncture device or needle can be manually opened or separated.
While the apparatus and method has or will be described for the sake of grammatical fluidity with functional explanations, it is to be expressly understood that the claims, unless expressly formulated under 35 USC 112, are not to be construed as necessarily limited in any way by the construction of “means” or “steps” limitations, but are to be accorded the full scope of the meaning and equivalents of the definition provided by the claims under the judicial doctrine of equivalents, and in the case where the claims are expressly formulated under 35 USC 112 are to be accorded full statutory equivalents under 35 USC 112. The invention can be better visualized by turning now to the following drawings wherein like elements are referenced by like numerals.
a is an enlarged perspective view of the embodiment of
The invention and its various embodiments can now be better understood by turning to the following detailed description of the preferred embodiments which are presented as illustrated examples of the invention defined in the claims. It is expressly understood that the invention as defined by the claims may be broader than the illustrated embodiments described below.
The invention is directed to a system and method for using a microneedle and stepped guidewire to micropuncture a body cavity or endovascular cavity and dispose a microguidewire therein for subsequent disposition of a larger guidewire and instrument such as an introducer or catheter while reducing tissue trauma at the puncture site and to the vascular system.
The illustrated embodiment comprises a splittable microneedle 16 as shown in
The preferred embodiment for the guidewire 8 is comprised of a centerless ground nitinol core guidewire with the proximal portion formed by a coil joined to the nitinol guidewire having an outer diameter of 0.038 inch over a 30 cm length with an intermediate portion consisting of a 1 cm long taper to a 30 cm long distal portion which is comprised of an 0.018 inch diameter nitinol mandrel guidewire from Lake Region Manufacturing Inc. in Chaska, Minn.
Another embodiment for the guidewire 8 is comprised of an 0.018 inch diameter nitinol mandrel guidewire from Lake Region Manufacturing Inc. in Chaska, Minn. that is about 60 cm long. A PEEK (polyetheretherketone, or any other stiff material) catheter (not shown) from Zeus Industrial Products Inc. in Orangeburg, S.C. can be bonded or heat shrunk to the proximal portion 12 of the guidewire 8 that it has an 0.032-0.038 inch outer diameter to provide the stiffness needed. This catheter may also be filled with different fillers (glass, talc, etc.) to change the stiffness of the proximal portion 12.
However, the functional requirement of distal portion 12 is that it be characterized as a microguidewire or have a diameter such that penetration of portion 12 into tissue and disposition into a vascular cavity reduces tissue trauma. The functional requirement of proximal portion 10 is that it be characterized as suitable for providing a guiding force to a larger diameter medical instrument, such as an introducer or catheter, which is telescopically disposed over portion 10. Thus, distal portion 12 is chosen with a size of diameter so that, when it is made of stainless steel, nitinol or other suitable material, which is flexible kink resistant and atraumatic but is not optimally configured to be used to guide a larger medical instrument in the vascular system. In the illustrated embodiment guidewire 8 is constructed on a NiTi core and overlaid in portion 12b with a sheathing made of a stainless steel coil. By the same token distal portion 12 causes a very little disturbance or tissue trauma through the small puncture wound through the skin and vascular wall provided by microneedle 16 through which portion 12 is led as shown in
The stepped guidewire 8 need not have a sharp step, but transitions its diameter in a reasonably short distance as suggested by
As shown in
Once the distal portion of the guidewire is positioned in the vascular cavity 14, microneedle 16 is split, separated or broken apart as per its design, and removed from guidewire 8 leaving the distal portion 12 through the puncture site. The means by which microneedle or micropuncture device 16 can be removed from guidewire 8 without pulling it over the proximal end of the guidewire 8 is not a limiting feature of the invention. Any construction by which microneedle or micropuncture device or a micropuncture device 16 can be separated or partially opened in order to be removed from the guidewire without having to be removed from the proximal end of the guidewire can be employed. In the illustrated embodiment a pair of diametrically opposed score lines 18 in
The guidewire 8 is then advanced into vessel 14 so that the proximal portion 10 smoothly enters the vessel 14 through the puncture site and is manipulated as per conventional methods to a vascular position as desired. An introducer or other instrument can then be telescoped over proximal portion 10 to the desired position. The extension of guidewire 8 provided by distal portion does not interfere with the use of proximal portion 10 as a guidewire, but may aid in steering the proximal portion of the guidewire through a tortuous vasculature. As a result the proximal portion of the guidewire may effectively steer a larger and stiffer medical device through complex vasculature while reducing initial tissue trauma upon puncturing the vasculature
The result is that a very small microneedle or micropuncture device 16 can be used to create a micropuncture with substantially less tissue trauma and risk to neighboring tissues at the site, less discomfort to the patient and with greater ease of placement than is the case with a needle or puncturing device which is large enough to accommodate the proximal portion 10 through it. Still when an introducer or other instrument needs to be guided over the guidewire 8 to the target site, this is possible by means of conventional manipulation of the proximal portion of the guidewire.
A preferred embodiment for the needle 16 shown in
Another embodiment of hub 24 is shown in the perspective view of
A larger medical device may be guided over guidewire 8 while distal portion 12 occupies the puncture pathway into the body cavity after microneedle 16 is removed from the puncture pathway, or guidewire 8 may be advanced first into the puncture pathway so that proximal portion 10 occupies the puncture pathway when the medical device is guided over guidewire 8. The latter method is preferred in that in many instances the use of the thicker proximal portion 10 of guidewire 8 will be necessary in order to avoid guidewire 8 from being backed out of the body cavity while the medical device is inserted, and/or the tracking of the medical device into the vasculature will be required in a manner that cannot be provided by the lighter, thinner and more flexible distal portion 12 of guidewire 8.
Another embodiment for the needle 16 as shown in
Many alterations and modifications may be made by those having ordinary skill in the art without departing from the spirit and scope of the invention. Therefore, it must be understood that the illustrated embodiment has been set forth only for the purposes of example and that it should not be taken as limiting the invention as defined by the following invention and its various embodiments.
For example and by way of a summary, various illustrated embodiments of the splittable needle include:, 1) A splittable needle 16 through which the smaller 0.018 diameter portion 12 of the guidewire 8 is passed through the needle 16 into the vessel, the needle 16 is withdrawn, split apart, and removed allowing the larger 0.038 portion 10 of the guidewire 8 to be advanced. 2) An over-the-needle splittable catheter design, for which a splittable catheter (not shown) is placed with the needle 16, the needle 16 is withdrawn, and the catheter is used to deliver the tapered guidewire 8. 3) A co-axial slotted needle 16 constructed of two closely fitted cannula 18, each with a 0.020″ wide slot 20 down the length. The needle 16 is placed with the slots 180 degrees opposed, and the hub 24 sealed, allowing the unit to be placed like a traditional needle. The small diameter portion 12 of the guidewire 8 is placed into the vessel, and the needle hub 24 is rotated 180 degrees so that the longitudinal slots 20 are aligned. The needle 16 can then be removed from the small diameter portion 12 of the guidewire 8. 4) A slotted needle 16 with an attached tightly fitted thin wall coaxial sleeve 22. The guidewire 8 is placed through the needle 16 into the vessel, and the needle 16 is withdrawn such that the guidewire 8 tears the thin wall sleeve 22, allowing the needle 16 to be removed from the 0.018″ portion 12 of the guidewire 8. This embodiment allows the needle 16 to be removed with one hand while the guidewire 8 is being held with the other hand, in one continuous motion. There is some stress applied to the guidewire 8 as it stresses the thin wall sleeve 22 to tear, so a nitinol guidewire 8 may be required to prevent kinking of the guidewire 8. The preferred embodiment utilizes a 21G regular or thin walled needle 16 with a 0.020″ wide slot 20 and a 0.00025″ wall sleeve 22 that is shrunk down over the needle cannula 18.
Therefore, it must be understood that the illustrated embodiment has been set forth only for the purposes of example and that it should not be taken as limiting the invention as defined by the following claims. For example, notwithstanding the fact that the elements of a claim are set forth below in a certain combination, it must be expressly understood that the invention includes other combinations of fewer, more or different elements, which are disclosed in above even when not initially claimed in such combinations. A teaching that two elements are combined in a claimed combination is further to be understood as also allowing for a claimed combination in which the two elements are not combined with each other, but may be used alone or combined in other combinations. The excision of any disclosed element of the invention is explicitly contemplated as within the scope of the invention.
The words used in this specification to describe the invention and its various embodiments are to be understood not only in the sense of their commonly defined meanings, but to include by special definition in this specification structure, material or acts beyond the scope of the commonly defined meanings. Thus if an element can be understood in the context of this specification as including more than one meaning, then its use in a claim must be understood as being generic to all possible meanings supported by the specification and by the word itself.
The definitions of the words or elements of the following claims are, therefore, defined in this specification to include not only the combination of elements which are literally set forth, but all equivalent structure, material or acts for performing substantially the same function in substantially the same way to obtain substantially the same result. In this sense it is therefore contemplated that an equivalent substitution of two or more elements may be made for any one of the elements in the claims below or that a single element may be substituted for two or more elements in a claim. Although elements may be described above as acting in certain combinations and even initially claimed as such, it is to be expressly understood that one or more elements from a claimed combination can in some cases be excised from the combination and that the claimed combination may be directed to a subcombination or variation of a subcombination.
Insubstantial changes from the claimed subject matter as viewed by a person with ordinary skill in the art, now known or later devised, are expressly contemplated as being equivalently within the scope of the claims. Therefore, obvious substitutions now or later known to one with ordinary skill in the art are defined to be within the scope of the defined elements.
The claims are thus to be understood to include what is specifically illustrated and described above, what is conceptionally equivalent, what can be obviously substituted and also what essentially incorporates the essential idea of the invention.
