Low profile venous access port assembly

A venous access port assembly having a housing base with a discharge stem, a septum, and a cap. An interior reservoir is defined by a well in the housing base and the bottom surface of the septum, and a passageway extends from the reservoir through the discharge stem. The cap is secured to the housing base and securely retains the septum in the assembly, compressing an annular flange of the septum against a septum seat of the housing base. Horizontal ribs on the interior of the cap snap into complementary grooves on the side wall of the housing base to mechanically lock together the cap and housing base during curing of the solvent bonding agent. The cap is mechanically secured and bonded to the housing base. Crush ribs on the interior surface of the cap, precisely center the cap about the housing base during assembly and compensating for manufacturing tolerances.

FIELD OF THE INVENTION

This relates to the field of medical devices and more particularly to catheter assemblies and ports therefor, for the infusion of fluids into the patient and withdrawal of fluids from the patient.

BACKGROUND OF THE INVENTION

Infusion ports for the infusion and/or withdrawal of fluids from a patient are well-known, secured to the proximal end of an implanted catheter. These ports are typically used for drug infusion or small amounts of blood withdrawal, where large flows of fluid are not required. The ports are assemblies of a needle-impenetrable housing with a discharge port in fluid communication with the catheter and the reservoir within the port housing, and provide a subcutaneous self-sealing septum that defines an access site for multiple needle sticks through the covering skin tissue of the patient, through the septum and into the reservoir, without the need to continuously search for new access sites. Examples of such ports are disclosed, for example, in U.S. Pat. Nos. 4,704,103; 4,762,517; 4,778,452; 5,185,003; 5,213,574 and 5,637,102.

It is desired to provide a venous access port assembly that is assuredly secured together in an assuredly sealed manner.

BRIEF SUMMARY OF THE INVENTION

The present invention is a venous access port having a housing and a septum, providing an interior reservoir and a passageway extending from the reservoir through a stem of a discharge port to establish fluid communication with a proximal end of a catheter lumen to which the port assembly is secured prior to placement of the assembly into a patient. The housing includes a base and a cap that together cooperate to secure a needle-penetrable septum within the assembly by compressing a seating flange of the septum in a seat of the housing base. The cap is mechanically secured to the housing base by a mechanical joint, preferably a retention rib of one of the housing base and cap extending radially outwardly to be received into a retention groove along the inside surface of the other of the housing base and cap in a snap fit, extending around most of the circumference of the port assembly. Preferably, solvent bonding is also provided between adjacent surfaces of the housing base and cap. The cap and housing base and septum are reduced in height from conventional ports to define a low profile venous access port assembly.

In a preferred embodiment of the present invention, a pair of horizontal retention ribs are defined on the cap's interior surface, a complementary pair of retention grooves are defined on the housing base's exterior surface. Due to manufacturing tolerances, a certain incremental “play” or gapping occurs between the facing surfaces of the cap and the housing base, and a plurality of crush ribs are provided along the interior surfaces of the cap, oriented vertically which minimize the effects of this “play.” During assembly of the cap to the housing base, the outer surface of the housing base crushes the crush ribs during the very final stages of the mechanical securing process; but the crush ribs serve to precisely center the housing base within the cap are within the incremental “play” or gapping. Just prior to mechanical assembly, solvent is applied to several selected surfaces of the housing base exterior and the cap's interior, and the crush ribs facilitate solvent wicking to the surfaces of the interface, resulting in a superior bond between the cap and the housing base.

DETAILED DESCRIPTION OF THE INVENTION

Certain terminology is used herein for convenience only and is not to be taken as a limitation on the present invention. The terms “distal” and “proximal” refer, respectively, to directions closer to and away from the insertion tip of a catheter in an implantable catheter assembly. The terminology includes the words specifically mentioned, derivatives thereof and words of similar import. The embodiments illustrated below are not intended to be exhaustive or to limit the invention to the precise form disclosed. These embodiments are chosen and described to best explain the principle of the invention and its application and practical use and to enable others skilled in the art to best utilize the invention.

Venous access port assembly10ofFIGS. 1 to 4includes a housing12and a septum14, with a discharge stem16extending from a distal end18of the port assembly10; discharge stem16is to be attached securely and sealingly to the proximal end of a catheter (not shown) such as by a locking sleeve or clamp (not shown). A passageway20extends from the interior reservoir22to the distal tip opening24of discharge stem16, along the longitudinal port axis. A recess26is seen to be provided along both sides of discharge port16, facilitating insertion of the discharge stem16into the catheter lumen and providing a clearance for a locking sleeve or clamp (not shown) utilized to compress the catheter lumen wall against the exterior surface of the discharge port16for assured sealed connection of the catheter with the port assembly10.

With reference now toFIG. 4, the interior of the port assembly10is shown to provide an interior reservoir22. Housing12is shown to include a housing base28of needle-impenetrable material that includes a well30having a bottom floor32and side walls34that define the interior reservoir22beneath septum14. Cap36is securable to housing base28to, in turn, secure septum14in position in the port assembly10. Cap36is described in greater particularity with respect toFIGS. 8 to 11. Cap36includes a base flange38extending radially outwardly from the bottom of well30of housing base28, and base flange38includes openings40that serve to enable suturing to the patient upon placement of the venous access port and the attached catheter into the patient.

Septum14is shown inFIG. 5and is seen to have a flattened top surface42and an annular seating flange44. Seating flange44is disposed upon a flange seat of housing base28, preferably under radially inward compression. Vertical compression of seating flange44is also attained when cap36is snapped onto housing base28, compressing seating flange44against flange seat46, as seen inFIG. 4. Also, seating flange44is seen to have rounded ridges48,50disposed on the upper and lower surfaces of seating flange44and extending completely around the septum, and are vertically co-aligned. The pair of rounded ridges48,50focuses greater compression circumferentially completely around the upper and lower surfaces of seating flange44upon assembly to assure sealing with respect to cap36and housing base28, and sealing the reservoir22.

InFIG. 6is seen discharge stem16which comprises a discrete component such as of titanium metal, that is insert molded to housing base28. Discharge stem16is shown to have a pair of axially spaced, annular, rounded, atraumatic ridges52that facilitate the mechanical connection of the catheter proximal end with the port assembly10.

Housing base28is shown inFIG. 7with discharge stem16already insert molded thereto. Its top surface is the flange seat46for septum flange44. A pair of grooves54are defined into side surface56of housing base28on opposite sides thereof and comprise a first retention section of the mechanical snap-fit joint between the cap and the housing base upon assembly. Adjacent the bottom surface of the housing base, and on the side opposite the discharge stem16is a tab58that facilitates the appropriate orientation of the housing base to the cap during assembly, in cooperation with tab-receiving recess60of cap36(seeFIGS. 9 and 10).

Cap36is illustrated inFIGS. 8 to 11and includes a top portion62that is generously rounded and is preferably dimensioned to extend at least as high as the septum's top surface42. Cap36also includes an annular side wall64that slopes downwardly and radially outwardly to skirt38adjacent cap bottom surface66. Top portion62extends radially inwardly to cover seating flange44of septum14when assembled. An interior cavity68of cap36is shaped and dimensioned to receive thereinto both seating flange44of septum14and the upper portion of side wall56of housing base28. Tab-receiving recess60is positioned opposite the distal opening for discharge stem16, for receipt thereinto of tab58of the housing base to appropriately orient the housing base and the cap for optimum functioning of the mechanical fastening system described below.

A second retention section, a pair of retention ribs70, is provided on the cap36around the greater part of the side surface of interior cavity68that corresponds with and is complementary to the first retention section or retention grooves54of housing base28, discussed above with reference toFIG. 7. Retention ribs70and retention grooves54provide a snap fit, assuredly mechanically securing cap36to housing base28. Preferably, retention ribs70may each have a radius of about 0.010 in (0.254 mm) and retention grooves54may have a radius of about 0.015 in (0.381 mm). Preferably, the retention ribs70of the cap comprise two coplanar horizontal portions equi-angularly spaced apart from each other, each extending circumferentially an angular distance between about 60° to 100° and more preferably between about 80° and 90° along the cap's interior surface; and the retention grooves54of the housing base28comprises two coplanar horizontal portions equi-angularly spaced apart from each other, each extending circumferentially an angular distance greater than that of the robs, and thus between about 70° to 110° and more preferably between about 85° to 95°.

A solvent bond is preferably formed between the facing surfaces of the septum, cap and housing base. The advantages of the mechanical retention of the cap to the housing base include assured securement of the cap and the housing base, in addition to the bonding thereof. Another advantage is more efficiency in the manufacturing of the venous access port assembly, and resultant economy: since the septum flange is under compression upon and after assembly, and since bonding is performed to further secure and seal the cap to the housing base, the mechanical lock holds the cap appropriately to the housing base while simultaneously maintaining appropriate compression of the septum flange, thus eliminating the necessity of tooling fixtures that otherwise would be needed to hold the three parts together until the bonding material fully cures.

Referring in particular toFIGS. 8 to 10, the present invention further includes providing a centering system operating to precisely center the housing base28within interior cavity68of cap36when being fastened together during assembly. A plurality of vertical crush ribs72are defined on one of the housing base and the cap at the interface therebetween. Preferably, the crush ribs72are provided on the interior surface of cap36at angularly spaced locations thereabout, and further, preferably, crush ribs72are offset angularly from the retention ribs70. During assembly of the housing base28to the cap36, the exterior surface of the housing base becomes engaged with the crush ribs, and may compress the very small dimensioned ribs. The crush ribs of the present invention take up any looseness, slack or incremental “play” between the housing base and the cap due to manufacturing tolerances, and further improve the solvent bond by assuring an evenly circumferentially distributed incremental gap at the interface between the housing base and the cap facilitating maximum wicking of the solvent to adjacent surfaces at the interface.

In the described embodiment, the crush ribs72are each positioned at an angular distance α from the longitudinal port axis on either side, such as 35°, as seen inFIG. 10. As seen inFIG. 11, each crush rib may have a very small radius of about 0.005 in (0.127 mm). The solvent may be, for example, tetrahydrofuran, and beads thereof may be provided on selected surface portions of the cap and the housing base along the interface therebetween, including, for example, the outer periphery of top cap surface46, the top of tab58, the bottom portion of housing base side wall56, and, after assembly, along the bottom surface of the assembly at the small cap/base interface gap.