Hollow curved superelastic medical needle and method

Abstract

A needle assembly 10 compromising an infusion needle 11 that includes a needle cannula 13 made of a superelastic material such as Nitinol. The needle cannula is cold-worked or heat annealed to produce a preformed bend 16 that can be straightened within passageway 21 of a coaxial outer cannula 12 for introduction into the body of a patient. Upon deployment from the outer cannula, the needle cannula substantially returns to the preformed configuration for the introduction or extraction of materials at areas lateral to the entry path of the needle assembly. The needle assembly can compromise a plurality of needle cannulae than can be variably arranged or configured for attaining a desired infusion pattern.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is filed under 35 U.S.C. 120 as a division of a patent application filed 9 Dec. 1999 in the name of Dr. James F. McGuckin, Jr. in whose name this application is submitted, and in the names of Avery J. Evans, Beth A. Kirts, Edward J. Morris and Robert L. Parter, which patent application has been accorded Ser. No. ______ and claims the benefit under 35 U.S.C. 119 of U.S. provisional patent applications 60 / 111624 filed Dec. 9, 1998 and 60 / 130,597 filed Apr. 22, 1999.TECHNICAL FIELD [0002] This invention relates generally to medical devices and more particularly to needles that are curved for indirect infusion access within the body. BACKGROUND [0003] Medical procedures involving the vertebrae are typically complicated because of the preciseness required to avoid both neural damage and injury to major blood vessels, as well as the indirect path that is usually required to access the treatment site. [0004] This is certainly ...

AI Technical Summary

Benefits of technology

[0017] The ability of the preformed inner needle cannula to deflect laterally upon exiting the outer cannula allows the inner needle cannula to infuse or aspirate material at multiple points within different planes in the body as the inner infusion needle rotates about its longitudinal axis. This helps to reduce or eliminate the need for additional “sticks” with the outer cannula; it also allows the operator to make an entry from one direction, then to deploy the curved inner cannula to reach a site that cannot be accessed directly, such as where another structure lies along the access path, thereby blocking the target site.

[0034] In addition to infusion or aspiration, the invention can provide a conduit for introducing and / or directing the path of other medical devices within the body such as radio-frequency ablation catheters or wire guides. This would allow a straight approach to a critical juncture whereafter the curved infusion needle can be deployed to precisely proceed to the desired anatomical site, especially in situations such as a luminal bifurcation or when access to an ostium is required.

Problems solved by technology

Medical procedures involving the vertebrae are typically complicated because of the preciseness required to avoid both neural damage and injury to major blood vessels, as well as the indirect path that is usually required to access the treatment site.

A single infusion usually cannot fill the entire target area because the needle tip cannot be redirected from the original plane of entry.

Continued infusion of cement from the first access site will usually not result in an adequate infusion due to the tendency of the material to set before it fills all of the affected area, thereby becoming a baffle to itself.

Furthermore, the thick density of the marrow and structures, such as veins, usually acts to impede free flow of the cement within the vertebral body.

Another concern during the procedure is accidental puncture of the these veins.

Because vertebral veins lead directly to the lungs, there is a significant risk of pulmonary embolism if cement is accidentally introduced therein.

The inability to adequately maneuver the needle cannula tip within a body or around structures is a major limitation of the straight needle.

Additional needle sticks to complete a medical procedure result in discomfort to the patient and additional risk of leakage and other complications.

Rigid curved needles are well known for suturing applications; however, adding anything more than a slight bend to an infusion needle limits its access path and ability to deeply penetrate tissue, especially bone.

For example, a rigid curved needle is unsuitable for use in a vertebroplasty procedure where the needle cannula must be driven through the bone and deep into the vertebral body using a relatively straight approach and maintained in place to avoid additional damage to the entry site.

Accomplishing this is problematic.

While stainless steel needles having a slight distal bend are known, the amount of needle curvature necessary to provide adequate lateral infusion is not possible—the needle plasticly deforms once inside the outer restraining cannula and hence is unable to return resiliently to its preformed shape.

Other medical procedures present similar problems when a single straight needle is used.

The problem is that the infusion may not penetrate any deeper than the needle tract; thus portions of the tumor are not effectively treated.

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