The present document describes a pressure guidewire comprising: a shaft tube with a proximal section; a middle section extending from the proximal section of the shaft tube, the middle section having greater flexibility than the proximal section; an inner hypotube installed substantially within the middle section for optimal mechanical properties; a pressure sensor with a communication means routed through the middle section and the proximal section; and a sensor housing for receiving the pressure sensor. There are also described methods for joining the inner hypotube to the shaft tube.