Abstract: A device to reduce left ventricle afterload in a target blood vessel in a mammal includes a cushion configured for positioning within a lumen of the target blood vessel and receipt of a fluid and configured to contract during systole and expand during diastole, a reservoir having a cavity for receiving the fluid, and a conduit extending between and fluidically coupling the cushion and the reservoir, whereby during use fluid in the cushion is transferred to the reservoir during systole and returned to the cushion during diastole. The cushion has an annular cross section defining a central lumen for blood flow and is configured for positioning in the lumen of the target vessel abutting an inner wall of the target vessel, whereby during use blood flow is directed through the central lumen of the cushion.