The present invention relates to a catheter system having a reinforced guidewire shaft and a method of manufacturing a reinforced catheter shaft. In particular, the present invention relates to a catheter shaft having two or more polymer layers and a reinforcement layer that is comprised of braids or a coil or combination thereof. The braided reinforcement layer may have a constant picks per inch (PPI) between braids or a variable PPI between braids. Similarly, the coiled reinforcement layer may have a constant pitch space between coils or a variable pitch space between coils. The reinforced catheter shaft may be manufactured by a continuous reel-to-reel process using liquid polymers that are heat-hardened or by a discrete process using extruded tube that is shrunk with heat.