Flow-directed catheter system and method of use

A flow-directed catheter comprising:

• a proximal body segment having a proximal end, a distal end, a lumen therethrough, a predetermined flexibility, a predetermined lumen diameter, and a predetermined outside diameter, said proximal segment having substantially constant lumen and outside diameters;
• and
• a distal body segment having a proximal end joined to the distal end of the proximal body segment, a distal end, a lumen therethrough, a predetermined flexibility, a predetermined lumen diameter and a predetermined outside diameter smaller than the outside diameter of the proximal segment, said distal segment having substantially constant lumen and outside diameters;
• wherein the distal body segment is adapted to follow blood flow, the proximal section is sufficiently rigid to provide column strength to manipulate the catheter from the proximal end thereof, and said distal end of the proximal segment is disposed immediately adjacent to the proximal end of the distal body segment and defines a transition region that is tapered to reduce the outer diameter of the proximal body segment to match the outer diameter of the distal body segment.