Transseptal delivery instrument

An apparatus for accessing a left side of a heart of a patient, comprising:

• an elongated structural member, adapted to be routed to the heart via a superior transvenous approach, comprising a seating structure on a distal portion of the structural member, the seating structure adapted to engage tissue adjacent to the ostium of the coronary sinus of the heart;
• a guide, coupled with the structural member, and adapted to carry a piercing instrument and adapted to reorient at a distal portion to direct the piercing instrument toward an inter-atrial septum of the heart;
• and
• a sliding member, coupled with the guide, and adapted to be controlled at a proximal end to reorient the distal portion of the guide.