A trans-atrial septal catheter system for delivery of a steerable sheath into the left atrium contains three components. The first component is a three-segmented needle-guide wire (10) composed of a distal needle (12) designed to flex sharply in relation to the conjoined looped guide wire segment (14) after fossa ovalis puncture and needle advancement. The distal guide wire loops are advanced into the left atrium maintaining the angled needle in a central location relevant to the loops for preserving an atraumatic position while stabilizing the loops in the left atrium. The elongated proximal extra stiff guide wire segment (16) is conjoined to the looped segment which crosses the fossa ovalis and extends proximally to become externalized to the femoral vein. This segment is extra stiff and significantly elongated to permit catheter and device exchanges. The guide wire serves as a support rail over which the dilator (108) and sheath (100) can be advanced into the left atrium. This transseptal system is uniquely forward looking and permits cautious and iterative delivery of the dilator into the fossa ovalis for "tenting" by way of a proximal sheath activator that interacts with the dilator. The proximal externalized GW is then advanced to permit puncture of the fossa ovalis. After puncturing a precise location of the fossa ovalis, the needle and coiled guide wire loops are further advanced into the left atrium. With the proximal activator (112), the dilator is advanced across the fossa ovalis into the left atrium using single-handed maneuvering for separate dilator advancement and steering of the sheath by way of turning or actuating the sheath handle.
