The present invention relates to a shaft for a catheter which may be usable having a tubular core which may be usable with a minimally invasive procedure such as intravascular medical treatment system. It also relates to a method of fabricating such shaft. The shaft has a longitudinal axis defining a radial distance, and a cross section having a polar axis defining an angular position, wherein the shaft comprises a tubular core which has an inner perimeter and an outer perimeter, and an outer layer for improving mechanical properties, which encloses the tubular core such that the outer perimeter of the core and the outer layer face each other, wherein the radial distance between the outer perimeter and the inner perimeter differs at different polar angular positions, forming zones of different stiffness at different angular positions, wherein different planes of the shaft oriented along the longitudinal axis and cutting the cross section at different polar angular positions have different flexural properties which are determined by the stiffness of the zones.