Microcatheter

Details Microcatheter Microcatheter

1998-05-12

2001-07-03

Nguyen, Anh-Tum T. (Department: 3763)

Surgery

Means for introducing or removing material from body for...

Treating material introduced into or removed from body...

C604S527000

Reexamination Certificate

active

06254588

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to catheters for medical diagnostic or therapeutic use. In particular, the present invention relates to microcatheters of the type particularly adapted for navigating tortuous pathways in soft tissues, such as the brain.
A wide variety of catheters have been developed, for percutaneous insertion into the vascular system to accomplish any of a number of diagnostic or therapeutic objectives. For example, a wide variety of balloon dilatation catheters adapted for percutaneous transluminal coronary angioplasty are known. Peripheral vascular dilatation catheters, angiography catheters, drug delivery catheters and others are well represented in the prior art.
However, due to the relatively large diameter and minimal tortuosity of the peripheral vasculature and, to a lesser extent, the coronary vasculature, the prior art catheters are typically unsuited for use in the small tortuous vessels, such as those found in the soft tissue of the brain and liver. In addition to size constraints imposed by such soft tissue vasculature, catheters suitable for these applications must also exhibit optimal flexibility, while at the same time maintaining adequate column strength and other desirable properties. In general, the known catheters for one reason or another are unsuited for intercranial catheterizations. Such catheterizations are useful for a variety of diagnostic and interventional neurological techniques including drug delivery, imaging, treatment of aneurysms, tumors, arteriovenous malformations, and the like.
For example, in angiography, catheters are designed to deliver a radio-opaque agent to a target site within a blood vessel, to allow radiographic viewing of the vessel and blood flow characteristics near the release site. For the treatment of localized disease, such as solid tumors, catheters allow a therapeutic agent to be delivered to the target site at a relatively high concentration, with minimum overall side effects. Methods for producing localized vaso-occlusion in target tissue regions, by catheter injection of a vaso-occlusive agent, have also been described.
Often the target site which one wishes to access by catheter is buried within a soft tissue, such as brain or liver, and is only reached by a tortuous route through vessels or ducts typically having less than about a 3 mm lumen diameter. The difficulty in accessing such regions is that the catheter must be quite flexible, in order to follow the tortuous path into the tissue and, at the same time, stiff enough to allow the distal end of the catheter to be manipulated from an external access site, which may be as much as a meter or more from the target site.
Two general methods for accessing such tortuous-path regions have been devised. The first method employs a highly flexible catheter having a inflatable, but pre-punctured balloon at its distal end. In use, the balloon is partially inflated, and carried by blood flow into the target site. The balloon is continually inflated during placement to replenish fluid leaking from the balloon. A major limitation of this method is that the catheter will travel in the path of highest blood flow rate, so many target sites with low blood flow rates cannot be accessed.
In the second prior art method, a torqueable guide wire having a distal bend is guided, by alternatively rotating and advancing the wire, to the target site. With the wire in place, the catheter is then advanced along the wire until the distal catheter is then advanced along the wire until the distal catheter end is positioned at the target site. An important advantage of this method is the ability to control the location of the catheter along a tortuous path. Torqueable guide wires which can be guided into delicate, tortuous, and narrow vasculature are available. However, it is often difficult or impossible to advance a catheter over the wire, especially where the wire extends along a tortuous path of more than about 10 cm. If the catheter is relatively rigid, it cannot track over the final distal portion of the wire in the tortuous path region, because catheter advancement buckles the wire in a narrow turn, or because catheter advancement pulls the wire out of the distal vessels. On the other hand, catheters having more flexible shafts, such as those used in balloon flow-directed devices, lack the column strength in the catheter's proximal section to be advanced over the guide wire without buckling.
The need in the art for suitably flexible and small diameter medical catheters is exemplified by the statistical prevalence of vascular disorders of the brain associated with stroke. Stroke is currently the third leading cause of death in the United States with an estimated annual cost of $30 billion. In the United States alone, stroke affects in excess of 500,000 Americans annually, resulting in 150,000 deaths. Current treatment options are relatively limited and generally highly invasive.
Thus, there remains a need in the art for the development of catheters useful in minimally invasive procedures to diagnose and treat vascular diseases of the brain, such as those associated with stroke, and other diseased sites accessible through only the small vessels of the circulatory system.
SUMMARY OF THE INVENTION
In accordance with one aspect of the present invention, there is provided a microcatheter for negotiating small tortuous vessels. The catheter comprises an elongate flexible body, having a tubular wall and at least one lumen extending axially therethrough. A first tubular element is provided in the wall, extending from a proximal end of the catheter through the body and terminating in a first distal zone. A second tubular element is provided in the wall, extending axially from a proximal end of the catheter through the tubular body and terminating in a second distal zone. Each of the first and second tubular elements is provided with a spiral cut in each of the first and second distal zones.
Preferably, the first tubular element is disposed coaxially within the second tubular element. The second distal zone is preferable axially displaced from the first distal zone.
In one embodiment, the catheter further comprises a spring coaxially disposed within the tubular wall. The spring may be positioned on the radially exterior side of the first tubular element and on the radially interior side of the second tubular element.
In accordance with another aspect of the present invention, there is provided a method of manufacturing a highly flexible small diameter catheter. The method comprises the steps of providing an elongate tubular element having a distal zone in which the tubular element is provided with a first spiral cut.
A spring coil is positioned coaxially about the outside of the first tubular element, such that the spring coil extends distally from a proximal end of the catheter to a point which is spaced apart proximally from the distal end of the first tubular element.
Preferably, a second tubular element is provided having a proximal solid walled zone and a distal spiral cut zone. The second tubular element is positioned coaxially about the spring coil, such that the second tubular element extends from the proximal end of the catheter to a point which is proximal to the distal end of the spring coil.
Preferably, an outer tubular jacket is positioned around the outside of the subassembly formed above, and the outer tubular jacket is radially reduced such as by the application of heat to form a highly flexible small diameter catheter.
Further features and advantages will become apparent from the detailed description of preferred embodiments which follows, when considered together with the attached drawings and claims.


REFERENCES:
patent: 4495134 (1985-01-01), Ouchi et al.
patent: 4516972 (1985-05-01), Samson
patent: 4669172 (1987-06-01), Petruzzi
patent: 4739768 (1988-04-01), Engelson
patent: 4941877 (1990-07-01), Montano, Jr.
patent: 4955862 (1990-09-01), Sepetka
patent: 4960410 (1990-10-01), Pinchuk
patent: 5085635 (1992-02-01), Cragg
patent: 517815

Affiliated with

Also associated with

Rating

Microcatheter does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Microcatheter, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Microcatheter will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2565644