A catheter pump assembly includes a catheter assembly that comprises a drive shaft 208 and a rotating impeller coupled to the distal end of the drive shaft. A driven assembly 201 is coupled to a proximal end of the drive shaft 208 within a housing 203. The catheter assembly includes a drive system 203 that comprises a motor 220 and a drive magnet 221 coupled to an output shaft of the motor. Further, a securing device is configured to prevent disengagement of the driven assembly housing from the drive assembly housing during operation of the pump. A distal end or tip portion (304, fig 13) of the catheter assembly (figs 13 & 14) is also disclosed and formed of a flexible material so as not to harm patient on insertion along a guidewire (312, fig 13).
