Catheters incorporating a thin film polymeric layer or layers. The thin film may have a wall thickness of about 0.00025+/less than 0.0001 to about 0.0015+/0.0002, for example. The thin film may be formed by extruding a sheet and cutting the sheet into elongate ribbons, each having two opposing long edges. The ribbon may be rolled or wrapped to define a tubular shape with a gap between the long edges. Heat and pressure may be applied to close the gap, abut the edges and form a longitudinal joint. The joint may extend along a portion of the length of the tubular shaft or most of the length of the tubular shaft. The tubular-shaped thin film layer may have a uniform wall thickness around the circumference, and the uniform wall thickness may extend across the joint.