Pericardial Blood as a Trigger for Postoperative Atrial Fibrillation After Cardiac Surgery

Background. Prevention strategies have long been sought to reduce the incidence and burden of postoperative atrial fibrillation (POAF) after heart surgery. However, none has emerged as a dominant and widely applicable prophylactic measure. The purpose of this review is to consider the biological mechanisms by which shed mediastinal blood leads to oxidation and inflammation within the postoperative pericardial environment and how this might trigger POAF in susceptible persons, as well as how it could represent a new target for prevention of POAF. Methods. We conducted a structured research of literature using PubMed and MEDLINE databases to May 2016. Biomolecular and clinical articles focused on assessing the contribution of pericardial blood, or the resulting inflammation within the pericardial space and its potential role in triggering POAF, were included in this review. Results. Evidence suggests that shed mediastinal blood through breakdown products, activation of coagulation cascade, and oxidative burst contributes to a highly pro-oxidant and proinflammatory milieu found within the pericardial space that can trigger postoperative atrial fibrillation in susceptible persons. The extent of this reaction could be blunted by reducing the exposition of pericardium to blood either through posterior pericardiotomy or improved chest drainage. Conclusions. Shed mediastinal blood undergoing transformation within the pericardium appears to be an important contributing factor to POAF. Strategies to prevent shed mediastinal blood from pooling around the heart might be considered in developing future paradigms for prevention of POAF. (C) 2018 by The Society of Thoracic Surgeons