| 摘要 |
An atherectomy device for removing tissue from an artery. The device includes a flexible, elongated drive shaft rotatable about a guide wire, the drive shaft having an enlarged diameter tissue removal section. The drive shaft and the enlarged diameter tissue removal section are comprised of helically wound wire. Wire turns of the proximal portion of the tissue removal section have diameters that gradually increase distally at a generally constant rate thereby forming generally the shape of a cone. Wire turns of the distal portion of the enlarged diameter tissue removal section have diameters that gradually decrease distally thereby forming a generally convex distal portion. At least part of the tissue removal section includes an external coating of an abrasive material to define an abrasive segment of the drive shaft. The drive shaft may include a reduced diameter segment located near the enlarged diameter tissue removal section to facilitate smooth rotation of the drive shaft and its tissue removal section about the guide wire when the atherectomy device is rotated at high speeds. Preferably such a reduced diameter segment is provided just proximal to the enlarged diameter tissue removal section, and preferably the entire portion of the drive shaft distal to the enlarged diameter tissue removal section also has a similarly reduced diameter. The maximum outer diameter and length of the abrasive segment may be selected so that, at operational rotational speeds and under load, at least some of the wire turns of the proximal portion of the enlarged diameter tissue removal section unwind from their at-rest diameter to an effective outer diameter which is the same as or larger than the maximum outer diameter of the abrasive segment. |
