Hello Max! Thank you for your question! I understand your concern and I would say that in your situation aortic valve replacement was the right thing to do coupled with the adequate efficacious antibiotic treatment. Regarding fluid appearance I believe it is a pericardial effusion (if you have an echo report please give me some concrete information about its severity). Pericardial effusion is not a rare finding in cardiac surgery (has been accused post pericardiotomic syndrome; also accumulation of blood especially in aortic valve surgery). The above mentioned causes are not life threatening, so don t worry! If is is needed the fluid can be drained by needle aspiration. I don t believe that the explanation of fluid form tissue surrounding aortic valve could have a different reason, such as an abscess ?!!! So please if you have any additional concrete information, such as echo report or something else send it to me for a more exact recommendation. Hope to have been helpful to you. Greetings from Dr. Iliri