BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a puncture needle assembly for providing access to arterial and venous blood vessels. Description of the Background Art

An important aspect of angiography and- vascular studies is access to the circulatory system, that is, to blood vessels such as arteries and veins. In such studies, access to the circulation typically involves insertion of a hollow needle into a groin artery, although the needle sometimes is inserted in a blood vessel in the arm. There have been problems with accurate insertion of previously known puncture needles into arteries of the groin or in the arm because of the awkward positioning required. When a needle is inserted into the blood vessel, the desired procedure is to puncture the front wall of the blood vessel and to stop the needle with the tip of the needle within the blood vessel itself without puncturing the back wall of the blood vessel. Proper positioning of the tip of the needle is determined by blood passing from the artery through the needle and out the back end of the needle. However, previously known puncture needles for accessing blood vessels for angio¬ graphy and vascular studies frequently must be griDDed with the thumb and two fingers. This usually requires that the back end of the needle be covered or concealed by the hand, due to the awkwardness of positioning previously known needles in a blood vessel in the qroin area or in an arm. Accordingly, a determination of the proper positioning of the tip of the needle is difficult with prior art puncture needles due to the back end of- the needle being covered by the hand.

There remains a need in the art for a puncture needle assembly for gaining access to blood vessels in the groin and the arm during angiography and vascular studies, that does not possess the disadvantages of prior art needles used for such purposes.

SUMMARY OF THE INVENTION In accordance with the present invention, a puncture needle assembly includes a hollow, open-ended stylet t ro gh which liquid may pass. The stylet is beveled at a distal end thereof to form a point on one side of the stylet, and a stylet hub assembly is fixed about a proximal end of the stylet. The stylet hub assembly includes a stabilizer fin extending outwardly from the stylet hub assembly in a plane defined by the longitud- inal axis of the stylet and the point of the beveled end of the stylet. The fin extends radially from a side of the stylet that is opposite the side on which the stylet point is located. A needle cannula is disposed exterior¬ ly on the stylet for slicably receiving the stylet. The needle cannula terminates at a proximal end thereof in a cannula hub having a body portion and further including a pair of wings extending outwardly from the cannula body portion. The wings have flexible hinge areas adjacent the cannula body portion that allow the wings to fold towards each other about the cannula axis. The body portion of the cannula b includes means for interacting with the stylet hub for releasably interlocking the cannula hub and the stylet hub assembly in a selectively locked position to prevent rotation of the stylet within the needle cannula. In the locked position, the beveled distal end of the stylet extends outside a distal end of the needle cannula and the stabilizer fin is disposed between the cannula wings and positioned subtantially equidistant from the hinge areas of the cannula wings so that the stabilizer fin can be gripped between the

cannula wings when the cannula wings are folded towards each other substantially symmetrically with respect to the plane of the stabilizer fin.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an assembled puncture needle assembly according to the invention. FIG. 2 is a side elevational view of the stylet portion of the puncture needle assembly shown in FIG. 1. FIG. 3 is a top elevational view of the stylet shown in FIG. 2, with a portion of the stylet fin broken away for clarity.

FIG. 4 is a detailed view, with oortions broken away, of the tip portion of the distal end of a puncture needle assembly as shown in FIG. 1. FIG. 5 is a detailed front elevational view of the distal end of the puncture needle assembly tip oortion shown in FIG. 4.

FIG. 6 is a top elevational view of the needle cannula of the puncture needle assembly shown in FIG. 1. FIG. 7 is a rear elevational view of the needle cannula shown in FIG. 6.

FIG. 8 is a rear elevational view of the ouncture needle assembly shown in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The assembled puncture needle assembly 10 according to the invention shown in Fig. 1 includes a hollow, open- ended stylet 12 through which liquid such as blood may pass. The stylet 12 is beveled at a distal end 14 to form a point 16 on one side 18 of stylet 12. The hollow stylet needle portion can be, for example, 18 or 19 gauge hollow, surgical stainless steel needle tubing. According to one embodiment, the overall bevel length (dimension C of Fig. 4) of the beveled end 14 of stylet 12 is 0.086 + 0.009 inch, the bevel includ- ing a sharpened edge portion 20 of the tip (dimension B

of Fig. 4) that comprises about 40-50% of the overall bevel length (dimension C of Fig. 4). According to this embodiment, bevel 14 has a bevel angle when viewed end-on of about 110 ^* + 5 ^β . See Fig. 5. A stylet hub assembly 22 is fixed about a proximal end of stylet 12. See Figs. 1, 2 and 3. The stylet hub assembly 22 includes a body portion 24 and a rigid stabilizer fin 26 extending outwardly from the-body - ^:; portion 24 of stylet hub assembly 22. Fin 26 is rigidly connected to the body portion 24 of hub assembly 22, and extends in a plane defined by the longitudinal axis of the hollow needle portion of stylet 12 and the point 16 of the beveled end 14 of the stylet, the fin extendinq radially from a side 28 of the stylet hub assembly 22 that is opposite the side 18 on which the stylet point 16 is located, as clearly shown in Fig. 2.

According to one embodiment, fin 26 is between about 1-2 inches in length (dimension F^ in Fig. 2) prefer¬ ably about 1-11/32 inches in length. According to this embodiment, the fin extends about 1/2-1 inch, Dreferably about 3/4 inch, outwardly from the axis of stylet 12 (dimension F_ of Fig. 2) .

As shown in Fig. 1, puncture needle assembly 10 includes a needle cannula 30 disposed exteriorly on stylet 12 for slidably receiving stylet 12. Advantage¬ ously, the cannula sleeve is formed of stainless steel or from a biocompatible plastic tubing. For a 19-gauqe stylet, a cannula having an outer diameter of 0.042 inch and an inner diameter of 0.035 inch is suitable, whereas for an 18-gauge stylet, a cannula having an outer diameter of 0.05 inch and an inner diameter 0.042 inch is suitable.

The cannula includes a distal end 32, and terminates at a proximal end thereof in a cannula hub 34 having a body portion 36. See Figs. 1 and 6. To reduce the

trauma of insertion, the cannula tip 31 is tapered as shown in Fig. 4, e.g., with a 0.015 inch by 0.001 inch bevel.

A pair of wings 38 extend outwardly from the cannula body portion 36, the wings having flexible hinge areas 40 adjacent the cannula body portion 36. See Figs. 1, 6 and 7. As shown in Figs. 1 and 8, the flexible hinge areas 40 allow wings 38 to fold towards each other about the cannula axis to grip the fin 26 extending from the stylet hub.

In preferred embodiments, the wings are connected perpendicularly to the hub by hinges 40 with the hinges on opposite sides of the cannula body portion with respect to the cannula axis, as shown clearly in Fig. 7. A rear connector portion 50 of the body portion 36 of the cannula hub extends a considerable distance from wings 38, for example, about 0.4 inch, terminating in a conven¬ tional "luer" lock hub portion 51 for connecting to a mating line connector. See Figs. 6 and 7. Means are provided for releasably interlocking the cannula hub and the stylet in position to prevent rota¬ tion of the stylet within the needle cannula. In the embodiment shown, this means for releasably interlocking the cannula hub and the stylet hub includes a locking tab 52 having a projecting end 54 fixedly connected to the stylet hub 22 between fin 26 and stylet 12. See Figs. 1, 2 and 3. The locking projection 52 of the stylet hub comple entarily fits within a slot 56 in a cannula hub with locking projection 54 fitting within a complementary depression 58 along slot 56 thereby interacting the cannula hub with the stylet hub for releasably interlock¬ ing the cannula hub and the stylet hub in a locked position to prevent rotation of the stylet within the needle cannula. With the stylet hub and cannula hub interlocked, the beveled stylet distal end 14 extends

beyond the cannula end 32, advantageously about 0.101 inch (dimension D in Fig. 4).

In the interlocked position, the stabilizer fin 26 is disposed between cannula wings 38, and positioned substantially equidistant from the hinge areas 40 of the cannula wings so that the stylet fin 26 can be gripped between the cannula wings 38 when folded towards each other substantially symmetrically with ^" respect to the plane defined by the longitudinal axis of the stylet and the point of the beveled end of the stylet.

In preferred embodiments, the cannula sleeve length (dimension S^ in Fig. 6) is from about 1 to about 2 inches, whereas the overall length of the cannula portion including the cannula hub (dimension C^ in Fig. 6) is from about 2-1/2 to about 3 inches. With a 19-gauge stylet, the preferred overall length is about 2.46-3.05 inches, and with an 18-gauge stylet, preferably from about 2.5T to about 3.10 inches. With a fin length of about 1-11/32 inches, a suitable wing width (dimension Wrø of Fig. 6) is about 0.508 inch, and a suitable wing length (dimension WL in Fig. 6) is about 0.594 inch with a wing tip to cannula axis length (dimension W^ in Fig. 6) of about 0.75 inch.

Advantageously, the cannula hub and wing portion are formed of one-piece plastic with the finger-gripping portions 60 of wings 38 being rigid and considerably thicker than the bendable hinge portions 40 connecting wings 38 to the body portion of the cannula hub. The gripping surfaces 62 of wings 38 are provided with a plurality of gripping dots 64 that interact with complementary gripping dots 66 on the outer surfaces of each side of the stabilizer fin 26 to assist in preventing axial movement of the stylet within the cannula when the puncture needle is assembled and in use with the stylet fin gripped between wings 38.

If desired, the end portion of the stylet hub can include a hub cap 68 with a central opening 70 through which blood may pass for indicating proper placement of the puncture needle in a blood vessel. See Fig. 1. The wings 38 of a puncture needle according to the present invention can be gripped by a thumb and one finger, with the stabilizing stylet fin 26 sandwiched therebetween. The wings 38 are displaced away frow the back end of the needle so that the back end is c e-arly visible while the needle is being inserted into a blood vessel and the flow of blood can immediately be detected through the back end of the needle. Gripping by means of the thumb and forefinger engaging the wings allows more convenient holding of the needle than with prior art devices, and facilitates greater accuracy in inserting the needle assembly. Alignment of the stabilizer fin 26 with the plane defined by the longitudinal axis of the stylet and the point of the beveled end of the stylet enables a physician to know from the position of the stabilizer fin the exact location of the beveled distal end 14 of stylet 12 while it is being inserted into a blood vessel, without blockage from view by the physician's hand of the opening 70 at the end of the stylet through which the first dripping of blood from the blood vessel can be detected.

Since many modifications, variations and changes in detail may be made to the described embodiments, it is intended that all matter in the foregoing description and shown in the accompanying drawings be interpreted as ^" illustrative and not in a limiting sense.