An apparatus, comprising: a left-ventricular assist device comprising: an impeller configured to be placed inside a left ventricle of a subject and to pump blood from the left ventricle to an aorta of the subject, by rotating; a frame disposed around the impeller; and a pump-outlet tube configured to traverse an aortic valve of the subject, such that a proximal portion of the pump-outlet tube is disposed within the subject's aorta and a distal portion of the pump-outlet tube is disposed within the subject's left ventricle, with the distal portion of the pump-outlet tube defining a distal conical portion, with the narrow end of the cone being distal with respect to the wide end of the cone, characterized in that: the frame is disposed within the distal portion of the pump-outlet tube; the distal portion of the pump-outlet tube extends to an end of a distal conical portion of the frame and defines more than 10 lateral blood-inlet openings configured to allow blood flow into the pump-outlet tube from the subject's left ventricle during operation of the impeller, with each lateral blood-inlet opening having an area of more than 0.1 mm 2 and less than 5 mm 2; and the distal conical portion of the pump-outlet tube is configured to reduce a risk of structures from the subject's left ventricle from entering into the frame, with the lateral blood-inlet openings being shaped such that in at least one direction the widths of the openings are less than 1 mm to block structures from the subject's left ventricle from entering into the frame. an impeller configured to be placed inside a left ventricle of a subject and to pump blood from the left ventricle to an aorta of the subject, by rotating; a frame disposed around the impeller; and a pump-outlet tube configured to traverse an aortic valve of the subject, such that a proximal portion of the pump-outlet tube is disposed within the subject's aorta and a distal portion of the pump-outlet tube is disposed within the subject's left ventricle, with the distal portion of the pump-outlet tube defining a distal conical portion, with the narrow end of the cone being distal with respect to the wide end of the cone, characterized in that: the frame is disposed within the distal portion of the pump-outlet tube; the distal portion of the pump-outlet tube extends to an end of a distal conical portion of the frame and defines more than 10 lateral blood-inlet openings configured to allow blood flow into the pump-outlet tube from the subject's left ventricle during operation of the impeller, with each lateral blood-inlet opening having an area of more than 0.1 mm 2 and less than 5 mm 2; and the distal conical portion of the pump-outlet tube is configured to reduce a risk of structures from the subject's left ventricle from entering into the frame, with the lateral blood-inlet openings being shaped such that in at least one direction the widths of the openings are less than 1 mm to block structures from the subject's left ventricle from entering into the frame. the frame is disposed within the distal portion of the pump-outlet tube; the distal portion of the pump-outlet tube extends to an end of a distal conical portion of the frame and defines more than 10 lateral blood-inlet openings configured to allow blood flow into the pump-outlet tube from the subject's left ventricle during operation of the impeller, with each lateral blood-inlet opening having an area of more than 0.1 mm 2 and less than 5 mm 2; and the distal conical portion of the pump-outlet tube is configured to reduce a risk of structures from the subject's left ventricle from entering into the frame, with the lateral blood-inlet openings being shaped such that in at least one direction the widths of the openings are less than 1 mm to block structures from the subject's left ventricle from entering into the frame.