Neuropsychological impairment is a common complication of coronary artery bypass grafting (CABG). Although the cause of this cerebral injury is unclear, one of the frequently discussed pathophysiologic features in relation to conventional CABG with extracorporeal circulation (ECC) is focal dys-regulation caused by cerebral emboli. The advent of transcranial Doppler ultrasonography (TCD) provided a sensitive tool for the detection of emboli in the majority of patients during traditional CABG with ECC. Furthermore, several studies using TCD have reported a correlation between the count of high-intensity transient signals (HITS) and neuropsychological outcome. This suggests that surgical techniques should be improved to reduce the number of emboli. CABG without ECC (off-pump surgery) on a beating heart is an increasingly common procedure and an interesting alternative to traditional revascularization, avoiding some of the morbidity of on-pump CABG surgery. Evidence for the reduction of cerebral HITS load in off-pump surgery has already been described. Nevertheless, inconsistent results were shown when the cerebroprotective effect of off-pump procedures was compared to conventional CABG. In the present study, we monitored the occurrence and frequency of HITS and compared the number of HITS resulting from CABG with ECC (on-pump CABG) or without ECC (off-pump CABG). We also wanted to determine whether a higher number of HITS is associated with an increased risk of short-term (6 days) and longterm (6 months) postoperative cognitive impairment. Do you like to spend your time reading scientific articles< In such a case you are welcome to the web site devoted to the medical science.
TCD cannot only detect HITS; the device also permits the continuous and simultaneous assessment of blood flow velocity (BFV) in the middle cerebral arteries (MCAs) through a “temporal window” in the intact skull. BFV may serve as a surrogate measurement of cerebral blood flow (CBF) since changes in flow velocities correlate closely with alterations in CBF, even when cerebral autoregulation is dis-turbed. Bilateral BFV measurements can evaluate the cognitively induced cerebrovascular reactivity by using cognitive tasks to elicit cerebral activation. The changes in BFV that result from this activation are sensitive enough to demonstrate lateralized mental activity (for a review of cerebral activation studies with functional TCD, see Stroobant et al). The second purpose of this study is to investigate the functional hemodynamic response by means of BFV measurements during rest conditions and during cognitive activation in patients before, early (6 days) and late (6 months) after the surgery. We assumed that reduced cognitively induced cerebrovascular reactivity could corroborate the observed neuropsychological deficits on a more metabolic level.