Immune Responsiveness and Outcome After Aortic Valve Surgery (Measure)

There is considerable morbidity and mortality associated with cardiac surgery. Currently little effort is made to quantify how well the immune system of an individual can cope with inflammation or infection to which they are exposed during surgery. The investigators have previously demonstrated that having higher pre-operative antibody levels is associated with a lower risk of infection and a shorter stay in hospital after cardiac surgery. The investigators aim to study 150 patients undergoing aortic valve replacement and explore their dynamic immune responsiveness. The investigators will determine if this response is correlated with the post-operative outcome (development of post-operative infection or increased length of hospital stay). The investigators will compare this response with the previously measured static markers of immune competence and also with a novel device that may give a more rapid measure of dynamic immunity. The investigators will approach patients in the cardiac surgical pre-assessment clinic to see if they are willing to participate in the study. Immediately once under anaesthetic blood will be taken for testing and then again at the end of surgery, 24h after surgery, at discharge from hospital, and at follow-up clinic approximately 4 weeks later. There will be no additional needle insertions on top of those routinely performed. The investigators will collect data from the routine observations as far as 1 year after surgery. If the investigators can show an association between immune function and subsequent post-operative outcome it may be possible to determine ways to improve outcomes for patients undergoing heart surgery. This might include better information on risks and benefits of surgery, actively boosting immune function (vaccination, immune-nutrition), passively improving immunity (administering antibodies), or consider current alternatives to open heart surgery where the threat of infection or inflammation may be markedly reduced (eg trans-catheter aortic valve implantation)