The systemic factor: The comparative roles of cardiopulmonary bypass and off-pump surgery in the genesis of patient injury during and following cardiac surgery

There is compelling evidence that off-pump coronary artery bypass operation s are associated with reduced circulating levels of inflammatory mediators. Whereas complement activation and release of acute-phase reactants such as interleukin-6 are still expected to occur as consequences of a nonbypass-r elated general surgical trauma, a major feature of off-pump surgery seems t o be a decreased production of interleukin-8, which may have important prac tical implications because of the participation of this cytokine in neutrop hil trafficking and myocardial injury. The scarcity of carefully controlled , randomized trials precludes firm conclusions regarding the extent to whic h these biological changes translate into meaningful improvements in clinic al outcomes. The problem is further complicated by the fact that the advers e effects of cardiopulmonary bypass largely depend on a genetically control led balance between proinflammatory and anti inflammatory mediators. Curren tly, it is still impossible to predict, in a given patient, the side toward which this balance will be shifted. Nevertheless, accumulating experience identifies patient subgroups who may greatly benefit from avoiding extracor poreal circulation. These subsets include patients with severe extracardiac comorbidities (in particular, renal failure) and, possibly, patients with advanced left ventricular dysfunction, who may poorly tolerate superimposed , bypass-related, inflammatory tissue injuries. (C) 2001 by The Society of Thoracic Surgeons.