Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1999-08-10
2001-07-03
Mendel, Manuel (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
Reexamination Certificate
active
06254568
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a deflectable catheter, and particularly to a deflectable electrode catheter having a straightening element.
BACKGROUND OF THE INVENTION
Steerable or deflectable tip cardiovascular catheters are useful in many applications, being a marked improvement over catheters with fixed tips. They are especially useful in the field of electrophysiology for performing radio-frequency ablation of cardiac tissue to interrupt abnormal electrical pathways in the heart. Typically, ablation catheters carry one or more electrodes at their distal end. A steerable catheter assists the physician in guiding the distal end of the catheter so that the electrodes can be properly aligned with the tissue to be ablated.
There are presently several useful designs for steerable tip catheters. Such a catheter generally has a control handle at its proximal end for controlling deflection of the tip in one or more directions. For example, U.S. Pat. No. RE 34,502, the disclosure of which is incorporated herein by reference, describes a catheter having a control handle comprising a housing having a piston chamber at its distal end. A piston is mounted in the piston chamber and is afforded lengthwise movement. The proximal end of the elongated, tubular catheter body is attached to the piston. A puller wire, typically made of stainless steel, is attached to the housing and extends through the piston, through the catheter body and into an off-axis lumen in the catheter tip section. The distal end of the puller wire is anchored in the tip section of the catheter. In this arrangement, lengthwise movement of the piston relative to the housing results in deflection of the catheter tip section.
A known disadvantage of the deflectable catheters is that after deflection, and particularly after repeated deflections in one direction, the tip tends to maintain a residual curve in that direction. In other words, the tip is unable to return to its original straight orientation when the deflecting force is removed. This is a result of the deformable nature of the material of the tip section and particularly of the stainless steel puller wire.
SUMMARY OF THE INVENTION
The present invention provides a deflectable catheter which overcomes the residual tip curve problem of known deflectable catheters.
In accordance with the present invention, there is provided a deflectable catheter having a catheter body, a tip section attached at the distal end of the catheter body and a control handle attached at the proximal end of the catheter body. The catheter body comprises at least one lumen extending therethrough, preferably a single central lumen. The tip section comprises at least one lumen, preferably at least two lumens, extending therethrough in communication with the lumen(s) of the catheter body. A puller wire is anchored at its proximal end to the control handle and extends through a lumen of the catheter body and tip section and is anchored at its distal end to the tip section. Longitudinal movement of the puller wire relative to the catheter body, accomplished by a suitable manipulation of the control handle, results in the deflection of the tip section.
To eliminate the “residual tip curve” problem arising out of the deflection, and especially repeated deflection, of the tip section, a straightening element is carried by the catheter tip section. The straightening element is made from a short section of a flexibly resilient material and may be any suitable shape. The material of the straightening element must have shape memory, i.e., be capable of substantially returning to its original shape after plastic deformation. Preferred elements include rods or wires having a circular cross-section and bars or plates having square or rectangular cross-sections. The diameter or cross-sectional width of the straightening element depends upon the material used. In a preferred embodiment, the straightening element is made of Nitinol wire having a circular cross-section with a diameter in the range of about 0.010 inches to about 0.020 inches, and preferably a diameter of about 0.014 inches. In an alternative embodiment, the straightening element may be made of a resilient plastic such as Peek.
In a preferred embodiment, the distal end of the straightening element is fixedly attached to or adjacent to the distal end of the tip section and extends proximally through the tip section and into the distal end of the catheter body wherein the proximal end of the straightening element is fixedly attached. Alternatively, the straightening element can be fixedly attached to the catheter at one of its ends and unattached at its other end. It is understood that the straightening element may be anchored completely within the tip section, i.e., not extending into the catheter body, if desired. The straightening element can be disposed in the same lumen as the puller wire, or alternatively, an additional lumen could be provided for carrying the straightening element separately from the puller wire. Preferably the puller wire and straightening elements are in diametrically opposed off-axis lumens in the catheter tip section.
When the catheter tip is deflected by applying a force to the puller wire, the straightening element deflects with the tip. When the force is removed from the puller wire, the resiliency of the straightening element biases the catheter tip section back towards its initial straight position so that the tip section has less and preferably no “residual tip curve.” The straightening element is particularly useful in unidirectional catheters using stainless steel puller wires. However, the use of straightening elements is also applicable to bi-directional and multi-directional steerable catheters.
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patent: 6033378 (2000-03-01), Lundquist et al.
Biosense Webster Inc.
Christie Parker & Hale LLP
Mendel Manuel
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