CATHETER

摘要

A catheter for ablating tissue, for example to treat a cardiac arrhythmia, includes a handle, a shapeable shaft and a distal ablation segment. The shaft retains a first position until manipulated to a further position with the application of moderate manual pressure. The shaft incorporates plastically deformable elements and is shapeable to conform to an insertion path or the particular anatomy of a patient for accessing a site to be ablated. Once shaped, the shaft retains its shape as the catheter is inserted or manipulated to the predetermined tissue treatment location and the distal segment is urged into contact with the tissue site. A deflection mechanism may be provided to facilitate navigation to, or to deflect the ablation segment into conformal contact with, the tissue target. In a further or alternative embodiment, a second or auxiliary shaft member extends distally from the ablation segment, allowing the segment to be threaded by or pulled past occluding tissue to a remote target tissue site. By gripping the end of the second shaft, the flexible ablation segment may be either tensioned or pulled inward against, or flexed and pushed outward against a treatment site, such as a region of the posterior epicardial wall, thus providing more effective contact for a broad range of dispositions and tissue orientations. In another embodiment, a thermal shield extends over a portion of the ablation segment, shielding adjacent tissue from damage while still effectively exposing the target tissue to ablation energy. The shield may be rotated or moved axially to delimit an area of cryogenic contact and achieve better protection of surrounding tissue structures in occluded or remote treatment target regions.