Patent ID: 8731664

Claim:
An axial flow rotary pump suitable for implantation into the human heart or vascular system, said pump having: (a) an elongate tubular casing having first and second ends and an internal cylindrical surface of said casing, (b) an inlet for blood into said pump at said first end of said casing, (c) an outlet for blood from said pump, said outlet being longitudinally spaced from said inlet, (d) an electric motor stator provided in said casing, (e) an elongate tubular rotatable element having an outer surface with an outer diameter and an inner diameter, said rotatable element being arranged to fit within said casing with clearance between said outer surface and said internal cylindrical surface, (f) a driveable electric motor rotor portion arranged to be driven by said electric motor stator, (g) a primary substantially axial blood flow path extending from said inlet to said outlet and along the inside of said tubular rotatable element, (h) a pumping chamber having therein a rotary impeller for impelling blood along said primary flow path, wherein said pumping chamber is axially spaced from said motor rotor portion to define an axial offset spacing between said pumping chamber and said motor rotor portion and wherein said pumping chamber has an internal diameter greater than the inner diameter of said tubular rotatable element, and (i) a secondary blood flow path in said clearance between the outer surface of said tubular rotatable element and the inner surface of said tubular casing.