A catheter shaft (10) having improved guide wire accessibility, reduced deflation time, and increased push, having a first tube (11), which forms a first lumen, and a second tube (12), which forms a second lumen and is disposed at least partially within the first tube (11), wherein the second tube (12) is welded, via the outer surface thereof, to the inner surface of the first tube (11), at least in sections, and to a catheter having such a catheter shaft. A simple and cost-effective method for producing such a catheter shaft or catheter.
