A guide wire has a distal end incorporating a coil and a capacitive element that form a resonance circuit with a resonance frequency that is responsive to the pressure of blood external to the guide wire. The resonance frequency can be detected wirelessly, or through two contacts at the proximal wire end, or through one brush contact located inside an insertion sheath and a ground electrode. Wireless detection can be implemented via a second resonance circuit, and electronics for determining the frequency when the first and second circuits are in resonance with each other.
