Catheter apparatus with weeping tip and method of use

#The present invention generally relates to surgical instruments and to instruments used to inject medicaments into a body wall or tissue.

#The direct introduction of a drug, compound, biologically active peptide or protein into the cells of a patient can have significant therapeutic value. However, this approach also has several drawbacks. Of primary concern is the risk of potential toxicity, particularly at dosages sufficient to produce a biological response to the peptide. From a practical perspective, there is also the problem of the cost associated with isolating and purifying or synthesizing the peptides. Moreover, the clinical impact of the peptides is also limited by their relatively short half-life in vivo, which usually results from their degradation by any proteases present in the target tissue.

#For these reasons, introduction of bioactive agents, including proteins, into a patient by delivery of a gene or a cell containing a gene that will express a therapeutic protein in the patient/host is an intriguing alternative to administering the substance. However, to date the principal means for introduction of foreign genetic material into a host has involved the integration of the gene into the host genome by, for example, transforming the host's cells with a viral vector. Direct in vivo gene transfer into postnatal animals has also been reported using DNA encapsulated in liposomes including DNA entrapped in proteoliposomes containing viral envelope receptor proteins.

#FIG. 1 is a schematic drawing showing an exploded view of the invention needle with weeping tip and a catheter to which it attaches.

#FIG. 2 is a schematic drawing showing the invention needle with the electrical connector for attachment to an electrocardiogram.

#FIG. 3 is a schematic drawing showing the invention surgical assemblage comprising a catheter and a needle, wherein the porous distal portion is located in the flexible catheter.

#The present invention overcomes many of the problems in the art by providing a surgical needle with a weeping tip for microinjection of medicaments into a body surface. The invention surgical needle comprises a nonporous hollow needle shaft having a proximal end adapted to mate with a surgical instrument, a porous distal portion in fluid-tight connection to the needle shaft, and a point that is open, closed, or has a solid partial plug. The distal portion of the invention needle is adapted to cause a liquid injectate to weep or ooze therefrom multidirectionally under injection pressure while the distal portion and point of the needle are inserted into a body surface. Typically, the length of the porous distal portion of the needle is determined by its intended use (e.g., whether intended for injecting medicament into a blood vessel or into a kidney, and the like). However, the porous distal portion is generally about 1 mm to about 20 mm in length and has pores with an average largest dimension in the range from about 1.0 micron to about 200 microns, for example, in the range from about 3 microns to about 100 microns, or from about 5 microns to about 75 microns.

#The invention surgical needle with weeping tip can be adapted for attachment to such surgical instruments as a syringe, but is preferably adapted for attachment to the distal tip of a nonporous catheter. The assemblage of the needle and catheter is preferably steerable. For example, the needle can be attached to the distal tip of a steerable catheter (i.e., comprising a steering mechanism at the handle for controlling deflection of the distal tip section of the catheter shaft), such as is known in the art for injection of medicaments into a remote body cavity or organ wall. Alternatively, the needle can be attached to a catheter with a porous distal portion and then the combination can be introduced into a steerable guidance catheter, such as is used in such surgical techniques as angioplasty, transmyocardial revascularization (TMR), percutaneous tnnnsmyocardial revascularization (PTMR), and the like, to direct the needle and catheter to the appropriate site for injection of a medicament Guidance catheters suitable for use in the invention assemblages and methods are commercially available, for example from such vendors as Eclipse Surgical Technologies (Sunnyvale, Calif.) and CardioGenesis Corp. (Sunnyvale, Calif.).

#In one embodiment according to the present invention, the surgical needle is fabricated from a metal commonly used to make surgical needles, such as stainless steel, nitinol, tantalum, elgiloy, and the like, and provided with a distal portion having a multiplicity of pores, while the proximal portion of the needle (i.e., the nonporous hollow needle shaft) is fluid-tight to prevent leakage of fluid therefrom. Consequently, in use it is important to insert the complete porous distal portion of the needle into tissue before and during injection of a medicament.