Abstract: An infusion catheter is formed with a catheter lumen extending from a proximal end connector assembly to a distal end valve that is normally closed but is penetrable to allow introduction of a guidewire through the catheter lumen and distal end valve and to thereby allow advancement of the infusion catheter over the guidewire, thereby allowing access of a distal infusion segment to a wide number of locations in the body. A plurality of, closely spaced, side wall infusion holes infusion holes extend from the catheter lumen through the catheter side wall in a high strength, catheter distal end, infusion segment. A therapeutic or diagnostic substance is pumped in a pulsatile manner through the catheter lumen under high pressure after removal of the guidewire and closure of the distal end valve. The infusion segment is preferably moved back and forth as jets of the therapeutic or diagnostic substance are emitted.