Postoperative brain damage and neuropsychological disorders have been observed in 30 - 80 % of patients after heart surgery with the use of cardiopulmonary bypass (CPB).They can persist up to a year after cardiac surgery and are associated with increased hospital mortality and prolonged intrahospital stay. Hypoperfusion,hyperthermia,atrial fibrillation,genetic predisposition and systemic inflammatory response associated with CPB have been identified as pathophysiological mechanisms.However, some authors consider cerebral embolisation to be the prevalent mechanism of intraoperative brain injury after cardiac surgery,as gaseous or solid cerebral emboli can cause ischemia, inflammation and edema,consequently causing cerebral infarctions usually resulting with stroke,coma,encephalopathy, delirium and cognitive decline. Additionally,they may impair cerebrovascular reactivity (CVR). Aortic valve replacement (AVR) preformed by full sternotomy is the standard approach in the treatment of aortic valve disease. Minimally invasive (MIS) aortic valve replacement has been shown to reduce postoperative mortality, morbidity, and pain while providing faster recovery, a shorter hospital stay, and better cosmetic results. However, due to technically more demanding procedure, MIS may lead to prolonged CPB time and incomplete de-airing of the heart with an increased risk for cerebral gas embolization. Therefore, the choice of MIS might bear an augmented risk for brain injury. Transcranial Doppler (TCD) enables real time detection of intraoperative emboli in the cerebral arteries seen as microembolic signals (MES), and is an essential neuromonitoring tool. Several studies demonstrated correlation between the number of MES and the occurrence as well as severity of postoperative neurological complications. However, the factors contributing to brain injury have not been elucidated in those studies. The investigators speculate that impairment of CVR is an important mechanism that persists and prolongs the duration of brain injury into postoperative period. The aim of the study is to compare two surgical approaches used for AVR, with focus on the number of MES and their impact on levels of protein S100B (marker of brain tissue damage),postoperative CVR and cognitive function With the results,the investigators aim to help surgeons in selecting the appropriate technique for AVR in individual participants,as well as to clarify the effect of aortic valve surgery on the brain.
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Detection of the intraoperative microembolic signals during minimal invasive sternotomy compared to full sternotomy with TCD during aortic valve surgery
Timeframe: Intraoperative detection:Beginning of surgery, after sternotomy, during aortic cannulation, during CPB, during de-aeration, opening of the clamp on the aorta and after CBP removal before chest closure.
Detection of S100B serum protein, marker of brain tissue damage
Timeframe: Before induction of anesthesia, 6 h , 24 h, 48h and 7 days after CPB
Detection of serum interleukin IL-1, IL-6,IL-8,Il-10 and Microparticles
Timeframe: Before induction of anesthesia, 6 h , 24 h, 48h and 7 days after CPB