Provided are a catheter pump and a treatment method that are capable of reducing the impact on cardiac valves, retaining an adequate flow rate, and facilitating flow of blood to coronary veins. This catheter pump (10) is inserted into a heart chamber to assist the flow of blood, and has a deformable cannula (30) which is provided with an inflow port (82) on the distal side thereof and discharge ports (83) on the proximal side thereof, and an impeller (50) disposed inside the cannula (30). The cannula (30) has: a proximal tubular part (32) within which the impeller (50) is disposed； a proximal end (36) which is located on the proximal side of the proximal tubular part (32), and the inner diameter of which decreases toward the proximal side； an intermediate tubular part (33) which is located on the distal side of the proximal tubular part (32), and which has an inner diameter smaller than that of the proximal tubular part (32)； and a distal tubular part (31) which is located on the distal side of the intermediate tubular part (33), and at which the inflow port (82) is located, wherein the discharge ports (83) are located in the outer peripheral surface of the proximal tubular part (32) and the proximal end (36).La présente invention concerne une pompe à cathéter et un procédé de traitement qui sont capables de réduire l'impact sur les valvules cardiaques, de maintenir un débit adéquat et de faciliter l'écoulement du sang vers les veines coronaires. Cette pompe à cathéter (10) est insérée dans une cavité cardiaque pour aider l'écoulement de sang, et comportant une canule déformable (30) qui est pourvue d'un orifice d'entrée (82) sur son côté distal et d'orifices de décharge (83) sur son côté proximal, et d'un rotor (50) disposé à l'intérieur de la canule (30). La canule (30) comporte : une partie tubulaire proximale (32) à l'intérieur de laquelle est disposé le rotor (50) ； une extrémité proximale (36) qui est située du côté proximal de la partie tubulaire proximale (3
