Reports of memory space impairment after cardiac surgery are controversial. severity of memory space impairment after coronary artery bypass grafting surgery in individuals at risk. Intro Although cognitive impairment is found in as many as 69% of individuals undergoing cardiac surgery at the time of hospital discharge 1 the causes for such impairment are still not established. Memory space deficit is a frequent getting4-6 and the most generally self-reported cognitive sign7 after coronary artery bypass grafting Rabbit Polyclonal to HDAC6. (CABG). Perioperative factors generating global and local impairment to cerebral function have been proposed as potential causes. Observation of undamaged emotional and interpersonal functioning in memory space deficient postsurgical individuals8 9 suggests that the impairment could be limited to memory space processing areas. In contrast it has been suggested that intraoperative global hypoxia could cause memory space deficit by influencing regions sensitive WP1130 to mind ischemia and involved in memory space processing such as the hippocampus.10 11 An understanding of the cerebral anatomical correlates of memory deficits after cardiac surgery could provide insight into the mechanisms of postoperative cognitive deficits and potentially help in development of therapeutic strategies. We hypothesized that mind areas associated with memory space processing are functionally jeopardized after CABG. To test this hypothesis we compared memory-induced changes in regional cerebral blood flow (rCBF) before and after surgery using positron emission tomography (PET). We were particularly interested in the medial temporal lobe and prefrontal cortex because human being memory space is predominantly processed in these areas.12 13 Methods The study was approved by Partner’s IRB Boston MA USA. Written educated consent was from all participants. The study involved eight native English-speaking right-handed individuals undergoing routine CABG (Table 1). Seven individuals underwent on-pump and one off-pump CABG (intraoperative decision). Due to technical reasons PET data could not be acquired in one patient preoperatively and another postoperatively. Accordingly we present data on six individuals. Table 1 Demographic and WP1130 Clinical Data Individuals were analyzed twice during overall performance of an explicit memory space task. The first series of scans were performed 1.5 [0.9-10.8] (median [interquartile range]) days before surgery and the second 6.5 [5.0-16.3] days after surgery. During these scans individuals were positioned in the PET video camera where they performed term stem completion jobs.12-18 The task began with a WP1130 study phase outside the scanner in which 135 terms (1 term/5s) were presented. Individuals were asked to indicate their liking/disliking for each term. At the end of the study phase individuals were scanned under control and test conditions. In the control condition the first 3 characters (term stem) of a word derived from the analyzed words was offered for 5s and individuals were asked to accomplish the stem using the 1st word that came to mind (e.g. picture for PIC). In the test condition related stems were presented and individuals were asked to accomplish them using WP1130 specifically the words from the study phase. Two control and two test blocks of 45 stems each were performed. The word lists were counterbalanced across individuals. The voice onset latency WP1130 and accuracy of reactions (% right retrieval) were recorded using a microphone channel connected to a voice-operated relay. Imaging protocols were similar to earlier descriptions.14-18 Briefly 15 labeled CO2 (15O-CO2) was delivered by nasal cannula (2L/min mean radioactivity 2960 MBq/L) and emission data acquisition started 30 s after beginning the word stem completion task (15-slice whole-body tomograph Scanditronix Personal computer 4096 General Electric Milwaukee WI). Images were reconstructed using measured attenuation correction and Hanning-weighted reconstruction filter arranged to allow 8-mm in-plane spatial resolution. Corrections were made for spread positron random coincidences and counting losses resulting from dead time in the video camera. Anesthetic management included premedication (midazolam 0.02-0.06 mg/kg) induction with propofol (0.5-1.5 mg/kg) fentanyl (10-20 mcg/kg) and muscle mass relaxation (cisatracurium vecuronium or pancuronium) and maintenance with isoflurane fentanyl and a muscle relaxant..