Disclosed is an assembly for fitting/removing a heart pump in a sleeve secured in an opening in a ventricular wall, the assembly including a guide element with a distal end, a proximal end, and a lumen extending between, and opening at, the distal and proximal ends, the heart pump having a pump body. With this pump body including an assembly element, the assembly includes a gripping unit which can slide in the lumen, the gripping unit having at its free end an assembly part which is complementary with the assembly element, which part is configured to cooperate with the assembly element, and to join this free end to the pump body, in order to permit the gripping and displacement of the heart pump.
