Ten female 80 kg pigs (Mixed Duroc and Landrace–Yorkshire) comprised the study material. One could not be weaned from extracorporeal circulation (ECC), resulting in 9 datasets available for analysis. The following 2 surgical groups were compared: single subvalvular annuloplasty ring versus double sub- and supravalvular annuloplasty ring. To minimize biological heterogenicity, both procedures were tested on the same animal, thus each animal acted as their own control. The study complied with Danish guidelines for animal research and was approved by the Danish Inspectorate of Animal Experimentation, no. 2013-15-2934-00915.