Disclosed herein is an inflow cannula for an implantable blood pump assembly. The inflow cannula includes a tubular body that extends from a proximal end to a distal end. The tubular body includes a proximal portion adapted for connection to a pump housing, and a distal portion adapted for positioning within an opening formed in a heart. The inflow cannula further includes an expandable sleeve coupled to an exterior surface of the distal portion. The sleeve has a first portion coupled to the distal portion of the tubular body, and a second portion extending from the distal end of the tubular body. The second portion is deployable from a first, stored configuration to a second, deployed configuration in which the second portion expands radially to engage and conform to an endocardial surface of the heart.