Steerable guidewire having electrodes for measuring vessel cross-section and blood flow

A steerable guidewire comprising:

• an elongated shaft having a distal end and a proximal end, said shaft being sufficiently torsionally rigid along its length for controllably transmitting to the distal end substantially all of the rotation applied to the proximal end, said shaft including a first electrical conductor and a second electrical conductor insulated from said first electrical conductor, said electrical conductors extending from the distal end to the proximal end of said shaft;
• and
• a tip attached to the distal end of said shaft, said tip adapted to be bent to a desired curve, said tip being sufficiently flexible so as to adapt to and follow the contours of a blood vessel, said tip including a distal electrode electrically connected to one of said conductors and a proximal electrode electrically connected to the other of said conductors, said electrodes being axially spaced apart on said tip by a predetermined distance, said distal electrode comprising a distal, conductive, helically-wound spring and said proximal electrode comprising a proximal, conductive helically-wound spring, said tip including a tapered distal region of said second conductor passing through said proximal spring at and least a portion of said distal spring and electrically connected to said distal spring.