1. Field of the Invention
The invention relates to the field of separable medical devices.
2. Description of the Prior Art
Separable medical devices are well known and typically include inter alia cardiac hemostatic valves and introducers, alone or in combination with each other. The reasons for desiring the separation of an introducer or medical device can be varied, but the most common usage is in connection with the removal of a first elongate instrument, such as a catheter or introducer, from a second elongate instrument, such as a guidewire, dilator, needle, catheter, pacemaker lead, another introducer or other medical device, when telescopic removal of the first instrument over the proximal end of the second instrument is not possible or convenient, the distal end of both the first and second instruments typically being at some point in time inserted within the body during a medical procedure. Endovascular procedures are the most common context of such usage, but the context includes endoscopic and other low invasive or noninvasive procedures as well.
Examples of such prior art separable devices are described in Lee U.S. Pat. Nos. 5,125,904 and 5,312,355 in the case of combined hemostatic valves and introducers. Additional prior art examples of separable valves, introducers or devices are disclosed in Philip O. Littleford, et al, “The American Journal of Cardiology,” Vol. 43, pp. 980-982 (May 1979); Littleford, U.S. Pat. Nos. 4,166,469; 4,243,050 and 4,345,606; Osborne, Re. 31,855, a reissue of U.S. Pat. No. 4,306,562; Boarini et al., U.S. Pat. No. 4,411,654; Moorehead, U.S. Pat. No. 4,983,168; Kousai et al., U.S. Pat. No. 4,883,468; Haindl, German Patent 3140915; Heck, U.S. Pat. No. 6,083,207; Lang, U.S. Pat. No. 6,712,789, Pohndorf U.S. Pat. No. 5,441,504 and many others, all of which are incorporated herein by reference. This listing of prior art separable devices is by no means comprehensive, but is illustrative of various endovascular applications using separable valves and introducers.
The various prior art devices allow for separation of an introducer or device by a plurality of different means, such as a preferred molecular orientation in the material being torn, a coupling or joint, a score line, a notch, a partial cut, a line of resiliently biased or compressed mechanical opening and sealing, or a molded line of relative weakness in the introducer or a wall of the device. All of these various mechanisms for allowing separation are referenced for the purposes of this specification as a “line of weakness”. The introducer or device is then separated on the line of weakness by ripping, failing, tearing, splitting, opening, cracking, fracturing or some other action of material separation.
However, the choice of separation mechanism in the line of weakness in a separable medical device will be dictated by many factors, including suitability of the material to use of the separation mechanism and cost of manufacturing the medical device with the chosen separation mechanism in it. What is needed is a separation mechanism that can be cost effectively used in molded medical devices and in particular in extruded tubes.
The illustrated embodiment is a separable medical apparatus comprising a wall and at least one capillary defined and enclosed within the wall to provide a zone of separation. The zone of separation comprises a thinning of the wall by presence of the capillary as compared to elsewhere in the wall where the capillary is not present.
In one embodiment the wall comprises a housing of a hemostatic valve, or housing of an introducer, sheath, catheter, cannula, or needle.
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 and 4b are partial cut away perspective views of a wall of uniform thickness of a medical device in which one or two capillaries are defined respectively.
a-5e are partial cut away perspective views of a wall of a medical device which illustrate various different embodiments where the capillaries are defined in different patterns in the wall.
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 illustrated embodiment is illustrated in an extruded tube 10 used or usable in a medical apparatus such as a catheter or introducer. The invention may be employed in combination with any medical device now known or later devised in which the device or a component thereof is separable. It is to be expressly understood that the invention can be broadly applied in various types of medical devices 12 and need not be limited to molded devices nor to devices having a tubular component 10. Further, wherever reference is made to “separable”, “separation”, or “separate”, it is to be understood for the purposes of this specification that any mechanism or process for dividing a body, whether it be opening the body on a single line or dividing a body on multiple lines, which mechanism or process is now known or later devised is included within the scope of meaning. For example, “separable”, “separation”, or “separate” is meant to include the concepts of peeling, shearing, splitting, cutting, ripping, tearing, fracturing, snapping, breaking, popping, exploding, failing, unzipping, unlatching, decoupling, coming apart, parting, opening, splaying, unfolding, uncurling, dividing, severing, sundering, detaching, disconnecting, unconnecting and all such similar concepts without limitation.
However, the invention is first illustrated as being embodied in a medical device 12 as diagrammatically shown in
In the embodiment of
It must be understood that lumen 22 of body 10 need not be central, but could be defined off center or in any radial position within body 10. In this respect it is not to be assumed that where two or more capillaries 16 are defined in wall 14 that they are necessarily of equal radius nor circular in cross section. For example, as seen in the perpendicular cross sectional view of body 10 in
The illustrations of
In the preferred embodiment body 10 is fabricated as extruded tubing, but may also be fabricated as a continuous film with no edges in which film capillary 16 is defined. In one embodiment body 10 assumes the form of an extruded a continuous film. Walls 14 of body 10 may be composed of polyethylene, polypropylene, fluorinated ethylene propylene (FEP), polyamide (PA), polyetherblockamide (PEBA), and in general any fluoropolymer, thermoplastic material, thermoplastic elastomer, thermoplastic vulcanate or thermoset material.
The illustrated embodiment of the invention may further comprise at least one handle 28 coupled to the tubular body 10 to facilitate separation of the tubular body 10 along the zone of separation 20 by manipulation of the handle 28.
The medical device which is combined with the tubular body 10 is not limited to a valve housing 30 as described above, but is expressly meant to include a separable introducer, sheath, catheter, cannula, or needle or a hub for the same. In such embodiments at least one handle 28 may extend from the separable introducer, sheath, catheter, cannula or needle. The handle 28 may be singular and be itself separable in two sections or two or more handles 28 may be provided. The handle 28 is arranged and configured to separate the introducer, sheath, catheter, cannula or needle so that when the handle 28 is pulled apart in two sections, the handle 28 or each handle section is coupled to a different portion of the introducer, sheath, catheter, cannula or needle between the two zones of separation defined by the capillaries 16. The handle 28 is arranged and configured to separate the separable hemostatic valve housing 30 and the introducer, sheath, catheter, cannula or needle (body 10 in
In such embodiments, the medical apparatus may further comprise a cut or notch 40 shown in
In the embodiment of
In any case, in the embodiments where a single capillary 16 is used to define a zone of separation 20, the zone of separation 20 is radially adjacent to the capillary 16 as indicated symbolically by the region in the locale of the dotted radial line segments 36 in
a illustrates an embodiment where wall 14, which need not be the wall of a tubular body, but a wall of any medical device without limitation, has an approximately uniform thickness in the neighborhood of capillary 16. Here the combined thickness of the two opposing zones of separation 20 is the difference between the uniform wall thickness and the diameter of capillary 16 in the direction perpendicular to the wall surface. The capillary wall thickness need not be half the difference, but may be asymmetrically divided.
Similarly,
c illustrates the embodiment where wall 14 has a nonuniform thickness in the neighborhood of a capillary 16. Wall 14 has been thickened in the embodiment of
Thus, in general, it is to be expressly understood that a plurality of capillaries 16 may be provided in wall 14 and defined in a pattern in the zone or zones of separation 20. In the embodiment of
In the preferred embodiment the material comprising body 10 is of such a nature that the zone of separation 20 comprises a line of tearing through the length of the capillary 16, preferably so that the capillary 16 is completely separated. By tearing it is meant that the zone of separation 20 begins to come apart at one location or end of the zone and then propagates continuously down the line of weakness until the entire capillary 16 is separated, much like unzipping a zipper according to the control of the manipulation of handles 28. However, it is entirely within the scope of the invention that the separation may be only partially propagated down the longitudinal axis 18 if desired or the separation may be more sudden, such as in a fracturing or snapping apart of the entire capillary 16.
Further, it is contemplated that a tool may also be employed to assist in the separation of capillary 16 by propagating the tearing or separation of the capillary. For example, an elongate tool can be disposed into the central lumen 22 or capillary 16, which tool is then used to expand lumen 22 or capillary 16 to stretch the capillary walls to tear or separate body 10.
In any case, in the preferred embodiments there is a line of tearing along the length of the longitudinal axis which comprises two longitudinal, azimuthally aligned, linear or curvilinear lines of separation. In the embodiments of
It is to be further understood that a gas, liquid or solid may be employed to fill capillary 16 in whole or part. For example, a stiffener or wire 38 as shown in the side cross sectional view of
In addition to the various structural embodiments described above the illustrated embodiment of the invention also encompasses a method for separating a tubular body 10 having a longitudinal axis and a wall 14 comprising the steps providing at least one capillary 16 defined and enclosed within the wall 14 of the tubular body 10, wherein the capillary 16 extends along the length of the longitudinal axis 18 and defines a zone of separation 20. The method applies a stress across the zone of separation 20 to cause the tubular body 10 to separate along the zone of separation 20. The method further comprises the step of manipulating at least one handle 28 coupled to the tubular body 10 to facilitate separation of the tubular body 10 along the zone of separation 20.
In one embodiment the step of applying the stress across the zone of separation comprises separating the wall radially adjacent to the capillary. This usually means separating the capillary wall through the thinnest shared portions of the walls of the tubular body 10 and the capillary 16. Preferably, applying a stress across the zone of separation 20 causes tearing along a line through the length of the capillary 16, which completely separates the capillary 16 along a tear. The tearing comprises completely separating the capillary 16 along two longitudinal, azimuthally aligned, linear or curvilinear lines. Usually this means separating the capillary 16 along the length of the longitudinal axis 18 at a single azimuthal position.
In one embodiment the method comprises the steps of providing a separable introducer, sheath, catheter, cannula, needle, hub or hemostatic valve, all symbolically denoted as element 30 in
The structure of the illustrated embodiment and the methods by which the embodiments are separated having been described, the method of fabrication of the illustrated embodiments is disclosed generally in the incorporated applications PCT/GB2005/003084 published as WO2006/016128 and PCT/GB2004/005196 published as WO2005/056272. However, the sake a clarity the preferred methods will be briefly summarized.
In this embodiment the extruder barrel 102 includes a 90° bend 124. Band heaters 126 are used to control the temperature at different stages in the extrusion apparatus 100. Band heaters 126 may be located within the extruder 100, on the flanges 116/122 on the gear pump 112, on the extruder barrel 120 and also on the die 114. The detail of the arrangement of the die 114 are shown in greater detail in
The process of fabrication of body 10 thus proceeds as follows. A polymer melt is produced in a screw extruder 104 and its resultant flow rate stabilized by means of a gear pump 112. This melt is then fed into a die 114 in the orifice of which is arranged a plurality of outlets 146 of needles 138 in a predetermined pattern. A conduit 142 through each needle 138 is fed from a horizontally orientated feed conduit 143, the entrance of which is open to atmosphere outside of the die 114 which is the fluid source 144.
The resulting extruded tube 10 is then passed over a series of rollers into a haul-off device (not shown). The speed of the haul-off device can be altered so that tubes 10 with differing draw ratios can be produced. The die 114 is designed such that the incoming flow from the extruder 100, which is contained in a circular pipe of a different diameter than orifice 136, and which is altered such that it may pass through the orifice 136 of the die 114. The die 114 must effect this geometry change, and this is currently achieved by using a convergent die 114. The die 114 is also designed so that the flow over the pattern of needles 138 is substantially even. An even melt flow around the needles 138 facilitates creation of well formed body 10.
The process is operated at about 165° C. using linear low density polyethylene (LLDPE). Other materials will require different temperatures according to conventional principles. The motor 106 is controlled using a pressure feedback loop that is set to 300PSI and this, in turn, causes a pressure of around a few bar in the die 114. Air is entrained as a result of the polymer flow over the pattern of needles 138 and the feed to this pattern is left open to the atmosphere.
The tear mechanism is disclosed generally in the incorporated application PCT/GB2005/003084 published as WO2006/016128, which is now summarized for clarity. It has been noted that when body 10 is prepared with thin film walls 14, tearing body 10 by pulling apart the two sides by hand at the rate at which one normally tears a piece of paper, body 10 splits into two parts along the capillary 16 and the edges of the two parts are fairly straight. However, when the body 10 is pulled apart at rates of 10 mm/s or less, the edges of the two parts into which the film is split are curvy and have a wavy edge. It has been found that the force required to tear a thin walled body 10 is different depending on the mode of tearing.
A Texture Analyzer manufactured by Stable Micro Systems was used to measure the force required to tear thin planar walls 14. The force required to tear a thin wall 14 quickly was measured by clamping one end of the wall 14 to the Texture Analyzer and pulling the other end by hand. The force required to tear the wall 14 slowly was measured by clamping both ends to the Texture analyzer and pulling them apart at a rate of 10 mm/s. The force required to tear quickly a wall 14 having a single capillary 16 was fairly constant and close to 2 Newton. The force required to tear such a typical thin wall 14 slowly varied between about 1 and 9 Newton. When the wall 14 was torn slowly, it was observed that a web of stretched material formed in the region where the two sides of the wall 14 were being pulled apart. As the web grew the force required to tear the wall 14 increased. Eventually, the web would break and the force would drop abruptly to its low value from which it would again increase as a new web formed. In some cases, as the wall 14 was torn slowly, the tear propagated away from the zone of separation 20 and the wall 14 split to one side. To ensure that the tear propagates along the zone of separation 20 it is important that the reduction in the cross section in the zone of separation 20 is appropriate for the anticipated tear speed and force given the wall thickness and material properties from which it is made.
It is proposed that this difference in the tearing mechanisms occurs due to the changes in the stress/strain curves for materials dependent upon the speed of the application of the strain. It is also noted that, in some cases it is difficult to initiate the tearing by hand and some assistance of initiation was required. This usually involved forming a slit, notch or cut 40 along the zone of separation 20 from which to initiate the tear.
Ideally, in order to have good tearing characteristics, there should be a rapid transition between a thinned region of body 10 in the zone of separation 20 and a thicker region of body 10 away from capillary 16 so that the stress concentration causes the thinned region to reach the fracture point of the extruded material before the thicker region of the material begins to plastically deform. In the stress/strain curve for most materials there is a stress barrier that must be overcome before plastic deformation occurs. Ideally the shape of the zone of separation 20 is such that at the anticipated tear speed, the fracture point of the material is reached within the zone of separation 20 before the stress in an adjacent thicker region increases above the stress barrier for plastic deformation. The shape of the transition, the difference in cross sectional area of body 10 and the tear speed all have an effect on the mode of tearing.
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.
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.
Number | Date | Country | Kind |
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0417664.0 | Aug 2004 | GB | national |
PCT/GB04/05196 | Dec 2004 | WO | international |
0328855.2 | Dec 2003 | GB | national |
The present application is a continuation-in-part application of PCT/GB2005/003084 filed on Aug. 5, 2005 and published as WO2006/016128, claiming priority to GB0417664.0 filed on Aug. 7, 2004, and of PCT/GB2004/005196 filed on Dec. 10, 2004, and published as WO2005/056272, claiming priority to GB0328855.2 filed on Dec. 12, 2003, which international applications are both incorporated herein by reference and to which priority is claimed pursuant to 35 USC 120 and 365(c).
Number | Date | Country | |
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Parent | PCT/GB05/03084 | Aug 2005 | US |
Child | 11473956 | Jun 2006 | US |