The present invention relates to a positioning system adapted to position and anchor one end of a medical device at a location where a pulmonary vein extends from an atrium, comprising: a transeptal sheath (50) adapted to be inserted through an atrial septum； an anchor device (10) having an elongate body with a proximal end portion and a distal end portion that is adapted to be positioned within the pulmonary vein, and also having an expandable member (14) along the distal end portion that is adjustable between a radially collapsed condition and a radially expanded condition that is adapted to engage the pulmonary vein after the distal end portion of the anchor device is advanced through the transeptal sheath and into the pulmonary vein； and a fixed corewire (18) within the elongate body, extending proximally from the distal end portion of the elongate body through at least a portion of the elongate body.an anchor device comprising an elongated tubular body having an expandable member disposed on its distal end portion.
