Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
2001-05-02
2003-07-01
Brinson, Patrick (Department: 3752)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S524000, C604S528000, C604S095040, C138S118000
Reexamination Certificate
active
06585718
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates generally to catheters, and more particularly to a catheter having a steerable distal-end region with a shaft support system for resisting axial compressive loads.
The heart beat in a healthy human is controlled by the sinoatrial node (“S-A node”) located in the wall of the right atrium. The S-A node generates electrical signal potentials that are transmitted through pathways of conductive heart tissue in the atrium to the atrioventricular node (“A-V node”) which in turn transmits the electrical signals throughout the ventricle by means of the His and Purkinje conductive tissues. Improper growth of, or damage to, the conductive tissue in the heart can interfere with the passage of regular electrical signals from the S-A and A-V nodes. Electrical signal irregularities resulting from such interference can disturb the normal rhythm of the heart and cause an abnormal rhythmic condition referred to as “cardiac arrhythmia.”
While there are different treatments for cardiac arrhythmia, including the application of anti-arrhythmia drugs, in many cases ablation of the damaged tissue can restore the correct operation of the heart. Such ablation can be performed by percutaneous ablation, a procedure in which a catheter is percutaneously introduced into the patient and directed through an artery or vein to the atrium or ventricle of the heart to perform single or multiple diagnostic, therapeutic, and/or surgical procedures. In such case, an ablation procedure is used to destroy the tissue causing the arrhythmia in an attempt to remove the electrical signal irregularities or create a conductive tissue block to restore normal heart beat or at least an improved heart beat. Successful ablation of the conductive tissue at the arrhythmia initiation site usually terminates the arrhythmia or at least moderates the heart rhythm to acceptable levels. A widely accepted treatment for arrhythmia involves the application of RF energy to the conductive tissue.
In the case of atrial fibrillation (“AF”), a procedure published by Cox et al. and known as the “Maze procedure” involves continuous atrial incisions to prevent atrial reentry and to allow sinus impulses to activate the entire myocardium. While this procedure has been found to be successful, it involves an intensely invasive approach. It is more desirable to accomplish the same result as the Maze procedure by use of a less invasive approach, such as through the use of an appropriate electrophysiological (“EP”) catheter system.
One such EP catheter system, as disclosed in U.S. Pat. Nos. 6,059,778 and 6,096,036, includes a plurality of spaced apart band electrodes located at the distal end of the catheter and arranged in a linear array. The band electrodes are positioned proximal heart tissue. RF energy is applied through the electrodes to the heart tissue to produce a series of long linear lesions similar to those produced by the Maze procedure. The catheters currently used for this procedure are typically flexible at the distal end, and the profile at the distal end is adjustable. However, when using such catheters, it is often difficult to conform the distal-end profile to some of the irregular topographies of the interior cavities of the heart. In other instances, it is difficult for a multi-electrode catheter that is designed to produce long linear lesions to access and ablate tissue in regions that require short linear lesions, such as the so-called isthmus region that runs from the tricuspid annulus to the eustachian ridge. Ablation of tissue in this region, and other regions non-conducive to the placement of multi-electrode, long, linear-lesion ablation catheters within them, is best accomplished by delivering RF energy to a tip electrode to produce localized spot lesions or if longer lesions are required, by energizing the tip while it is moved across the tissue.
Other catheters for producing spot lesions or tip-drag lesions typically include a tip ablation electrode and a plurality of mapping band electrodes positioned at the distal end of the catheter. The catheters are steerable in that they are configured to allow the profile of the distal end of the catheter to be manipulated from a location outside the patient's body. Steerable catheters that produce multiple deflection profiles of their distal ends provide a broader range of steerability. However, known steerable catheters, such as that disclosed in U.S. Pat. No. 5,195,968, have steering tendons attached to a ribbon at or near the longitudinal centerline of the catheter. Because of the relatively short distance between the tendon attachment point and the ribbon that resides along the centerline of the catheter sheath, a force applied to the tendon results in a relatively small bending moment for deflecting the distal tip. The ribbon/tendon assembly is typically provided clearance to allow the tendon to become substantially displaced from the centerline as deflection progresses, thereby enlarging the moment arm and consequently increasing the applied bending moment. Unfortunately, this requires such designs to include additional lumen space, translating into larger catheter diameters. Larger diameter catheters are undesirable due to the increased trauma they inflict on a patient. Further, as the tendon displaces to the extent that it contacts the catheter wall, the associated friction may necessitate greater exertion to further deflect the distal tip. Lessening the amount of force required to deflect the distal tip of a catheter by actions outside the catheter is desired in that the catheter tip can more easily be deflected and placed in the correct location within a patient.
In some catheters that have a ribbon within the distal-end region and a steering tendon affixed to the sheath at a point proximal the distal tip within the distal-end region, undesirable deformation of the sheath can occur when the steering tendon is axially displaced in the proximal direction. More specifically, as the steering tendon is axially displaced in the proximal direction, the portion of the sheath in the distal-end region proximal the attachment point compresses, thus causing the sheath to wrinkle, and the portion of the sheath distal the attachment point stretches. Such deformation of the sheath can lead to fluid ingress beneath the catheter's band electrodes or can cause damage to internal wires or mechanical components.
Hence, those skilled in the art have identified a need for a tip-electrode, ablation catheter with a steerable distal-end region that resists deformation even after repeated steering. The present invention fulfills these needs and others.
SUMMARY OF THE INVENTION
Briefly, and in general terms, the present invention is directed to a catheter with a steerable distal-end region and a shaft support system for resisting axial compressive loads.
In a first aspect, the invention relates to a catheter that includes a sheath having a proximal region, a distal-end region, and a longitudinal centerline. The catheter also includes at least one steering tendon that is housed within the sheath. The at least one steering tendon has a first end that is attached to the distal-end region of the sheath, and a second end that is located at the proximal region of the sheath. Movement of the at least one steering tendon in a proximal direction causes the sheath distal-end region to deflect. The catheter also includes a support system having a proximal end, a distal end and a lumen there between. The support system is sized to fit within the distal-end region of the sheath and is configured to deflect laterally relative to the centerline and to resist axial compression along the centerline.
In a detailed aspect of the invention, the support system includes a helical coil that defines the lumen and at least one strut that is secured to one side of the coil along the length of the coil. In another aspect, the support system includes a pair of struts secured to diametrically opposite sides of the coil. In a further aspect, the support system is forme
Bowe Wade A.
Flores Jesse
Hayzelden Robert C.
Moore Andrea M.
Simpson John A.
Brinson Patrick
Cardiac Pacemakers Inc.
Fulwider Patton & Utecht, LLP
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