A catheter comprises a tubular body wherein at least a portion of the tubular body includes a helical reinforcement element. Both the tubular body and the helical reinforcement element are composed of polymeric materials, and the reinforcement element is fused to the material of the tubular by applying heat and radially constrictive pressure. In this way, a helical reinforcement element providing significant hoop strength can be embedded within the tubular body with decreased risk of delamination. Optionally, an axial reinforcement element may be embedded within the tubular body between the helical reinforcement element and an outer portion of the tubular body matrix.