A catheter with a guidewire shaft (1) with a proximal end which is free to move, the proximal end of the catheter having either a dual lumen (14) embodiment or a single lumen (6) embodiment. The dual lumen (14) embodiment has a stiffening wire lumen (17) through which a stiffening wire (12) extends and...http://www.google.co.uk/patents/US5545138?utm_source=gb-gplus-sharePatent US5545138 - Adjustable stiffness dilatation catheter
