An infusion catheter and method, with an elongated shaft having a guidewire lumen which has a proximal section and a common distal section extending to a distal port at a distal end of the shaft, and an infusion lumen which is in fluid communication with the distal port of the guidewire lumen and which joins the common distal section of the guidewire lumen at a location distal to the guidewire proximal port. A restricted passage from the infusion lumen to the common distal section of the guidewire lumen has a smaller transverse dimension than the guidewire lumen and a guidewire slidably disposed in the guidewire lumen.