A device (200) for implantation in or near an annulus of a tricuspid valve comprising at least one blood flow control element (202) adapted to capture a volume of blood therein. Optionally or alternatively, the blood flow control element is adapted to allow at least some volume of blood (406) to regurgitate through the annulus during at least some part of systole. Optionally or alternatively, the device comprises a relatively rigid annulus with an arc length of less than 300 degrees. Optionally or alternatively, the relatively rigid annulus comprises a plurality of tissue fixation elements positioned along no more than 300 degrees of a circumference of the annulus, for example to avoid damaging conduction pathways between an atria and a chamber.