An apparatus comprising: a ventricular assist device comprising: an impeller configured to be placed inside a left ventricle of a subject, the impeller comprising proximal and distal bushings (64, 58); a frame configured to be disposed around the impeller, the frame comprising proximal and distal bearings (116, 118); an axial shaft configured to pass through the proximal and distal bearings (116, 118) of the frame and the proximal and distal bushings (64, 58) of the impeller; a motor configured to drive the impeller to pump blood from the left ventricle to an aorta of the subject, by rotating the impeller, characterised in that the impeller is configured to undergo axial back-and-forth motion with respect to the frame, in response to cyclical changes in a pressure difference between the left ventricle and the aorta, and in that the impeller is coupled to the axial shaft such that the impeller causes the axial shaft to undergo axial back-and-forth motion with respect to the proximal and distal bearings (116, 118) of the frame; and a distal tip element disposed at a distal end of the ventricular assist device, the distal tip element defining: an axial-shaft-receiving tube, configured to receive at least a portion of the axial shaft during forward motion of the axial shaft; and a distal tip portion disposed distally of the axial-shaft-receiving tube, the distal tip portion being configured not to injure tissue of the subject, even if the distal tip portion comes into contact with the tissue. a ventricular assist device comprising: an impeller configured to be placed inside a left ventricle of a subject, the impeller comprising proximal and distal bushings (64, 58); a frame configured to be disposed around the impeller, the frame comprising proximal and distal bearings (116, 118); an axial shaft configured to pass through the proximal and distal bearings (116, 118) of the frame and the proximal and distal bushings (64, 58) of the impeller; a motor configured to drive the impeller to pump blood from the left ventricle to an aorta of the subject, by rotating the impeller, an impeller configured to be placed inside a left ventricle of a subject, the impeller comprising proximal and distal bushings (64, 58); a frame configured to be disposed around the impeller, the frame comprising proximal and distal bearings (116, 118); an axial shaft configured to pass through the proximal and distal bearings (116, 118) of the frame and the proximal and distal bushings (64, 58) of the impeller; a motor configured to drive the impeller to pump blood from the left ventricle to an aorta of the subject, by rotating the impeller, characterised in that the impeller is configured to undergo axial back-and-forth motion with respect to the frame, in response to cyclical changes in a pressure difference between the left ventricle and the aorta, and in that the impeller is coupled to the axial shaft such that the impeller causes the axial shaft to undergo axial back-and-forth motion with respect to the proximal and distal bearings (116, 118) of the frame; and a distal tip element disposed at a distal end of the ventricular assist device, the distal tip element defining: an axial-shaft-receiving tube, configured to receive at least a portion of the axial shaft during forward motion of the axial shaft; and a distal tip portion disposed distally of the axial-shaft-receiving tube, the distal tip portion being configured not to injure tissue of the subject, even if the distal tip portion comes into contact with the tissue. an axial-shaft-receiving tube, configured to receive at least a portion of the axial shaft during forward motion of the axial shaft; and a distal tip portion disposed distally of the axial-shaft-receiving tube, the distal tip portion being configured not to injure tissue of the subject, even if the distal tip portion comes into contact with the tissue.