Abstract: An artificial ventricle for use as part of a total artificial heart for implantation within a living being as part of its circulatory system. The ventricle includes a soft and flexible blood pumping sac which can be collapsed to the substantially flattened, squeezed or rolled-up structure of much reduced size. The sac includes inlet and outlet ports to permit the flow of blood therethrough and is contained within a semi-rigid and removable enclosure which provides pumping means for driving blood flow through the ventricle. The semi-rigid shell includes open and closed configurations to allow emplacement of the shell around an attached ventricle already sutured in place as part of the circulatory system. Removal of the rigid shell is likewise feasible without disturbing the attached ventricle.