Agent delivery catheter having a radially expandable centering support members

An agent delivery catheter configured for delivering an agent to an injection site in a wall of a patient's body lumen, comprising:

• a) an elongated shaft having a proximal end, a distal end, a needle-through lumen slidably containing a needle therein, and at least one needle-through port in a side of a distal shaft section for lateral egress of the needle, such that the needle has a retracted and an extended configuration;
• and
• b) an expandable member on the distal shaft section, which has a collapsed configuration, and a radially expanded configuration having a portion in direct contact with the outer surface of said shaft at the radial location of the port on the shaft side opposite to the port-side of the shaft expanded into contact with the body lumen wall, and which extends around the circumference and along an outer surface of the shaft to substantially center the distal shaft section at the location of the port in the body lumen in the expanded configuration, such that the expandable member in the expanded configuration allows perfusion of fluid within the body lumen along a surface of the expandable member from proximal to the expandable member to distal to the expandable member and supports the shaft in a position spaced away from the body lumen wall around the circumference of the shaft at the location of the port, and the needle slidably exits the needle-through lumen in the extended configuration through the port spaced away from the body lumen wall as the expandable member supports the shaft at the port.