Apparatus and methods are described including implanting an aortic pressure-loss-reduction device (20) in a subject's ascending aorta. While the device is inside a catheter (42), a distal end of the catheter is placed within the ascending aorta. A proximal covering sheath (44) of the catheter is retracted such as to uncover at least a portion of a downstream anchor (31), such that the uncovered portion of the downstream anchor includes a portion of the frame that does not have material coupled thereto. Subsequently, a distal covering sheath (45) of the catheter is advanced, such as to cause an upstream anchor (33) to anchor an upstream end device (20) to the subject's ascending aorta, by the upstream anchor radially expending against an inner wall of the ascending aorta. Other applications are also described.