Patent ID: 7635346

Claim:
Apparatus for use in a body lumen having a proximal opening, the apparatus comprising: first and second fluid pressure sources; an elongate carrier, adapted to be inserted through the proximal opening of the body lumen; an inflatable piston head coupled to a distal portion of the carrier, and adapted to form a pressure seal with a wall of the lumen after the carrier has been inserted into the lumen; a first passageway in fluid communication with the first pressure source and a proximal portion of the lumen proximal to the piston head; a second passageway in fluid communication with the second pressure source and the piston head; first and second pressure sensors, adapted to measure a first measurable pressure in the proximal portion of the lumen, and a second measurable pressure in the piston head, respectively; and a control unit, adapted to cause the piston bead to be advanced distally in the lumen by: while the first pressure source applies a first applied pressure to the proximal portion of the lumen, regulating the second measurable pressure in the piston head to be equal to the first measurable pressure in the proximal portion of the lumen plus a positive value, by driving the second pressure source to apply a second applied pressure.