Inflammatory Complications after Cardiac Surgery: Atrial Fibrillation and Kidney Injury

Abstract

Heart surgery is a frequently performed type of surgery and is associated with an inflammatory response throughout the body. This inflammation can injure several organs, including the heart itself and the kidneys. This thesis has investigated the role of the systemic inflammatory response after open-heart surgery in two common postoperative complications, atrial fibrillation and kidney injury. The theory that inflammation is a causative pathophysiological factor in the development of complications after cardiac surgery is only partly supported by this thesis. Atrial fibrillation in the postoperative period is a complex arrhythmia with multiple mechanisms underlying its pathology, whereby atrial remodeling through effects of inflammation may only play a minor role. Since direct cardiac manipulation and myocardial incision takes place in the atria, where atrial fibrillation develops, it is more likely that these factors along with individual structural and anatomical remodeling pre- and postoperatively are responsible for the evolution of the arrhythmia. It is recommended that future studies investigate individual perioperative conditions which could underlie such arrhythmogenic mechanisms. Future research could also focus on elucidating subtle and delicate local pathophysiological changes in the atrial myocardium while determining individual patient-related factors. Personalized management strategies could then be applied rather than administering anti-inflammatory drugs to the general cardiac surgical population. In contrast to atrial fibrillation, the inflammatory response with its accompanied ischemia-reperfusion injury appear to play an important role in the development of severe kidney injury. The kidneys have a very delicate vasculature and changes as hypoxemia or hypoperfusion leading to inflammation appear to result in more injury than in myocardial tissue. Corticosteroids are potential drugs that can reduce the incidence of renal replacement therapy postoperatively. However, these drugs appear to have the most beneficial effects in patients with advanced chronic kidney disease preoperatively. These high risk patients who are most liable to develop severe acute kidney injury postoperatively, and as such benefit most from preventive strategies, can be identified with a simple predictive risk model. Young age is, in contrast to all what is presently thought in medical literature, is a risk factor, instead of a protective factor, for postoperative need for dialysis.