Perioperative antiplatelet therapy.

Aspirin is recommended as a lifelong therapy that should never be interrupted for patients with cardiovascular dis- ease. Clopidogrel therapy is mandatory for six weeks after placement of bare-metal stents, three to six months after myocardial infarction, and at least 12 months after placement of drug-eluting stents. Because of the hypercoagulable state induced by surgery, early withdrawal of antiplatelet therapy for secondary prevention of cardiovascular disease increases the risk of postoperative myocardial infarction and death five- to 10-fold in stented patients who are on continuous dual antiplatelet therapy. The shorter the time between revascularization and surgery, the higher the risk of adverse cardiac events. Elective surgery should be postponed beyond these periods, whereas vital, semiurgent, or urgent operations should be performed under continued dual antiplatelet therapy. The risk of surgical hemorrhage is increased approximately 20 percent by aspirin or clopidogrel alone, and 50 percent by dual antiplatelet therapy. The present clinical data suggest that the risk of a cardiovascular event when stopping antiplatelet agents preoperatively is higher than the risk of surgical bleeding when continuing these drugs, except during surgery in a closed space (e.g., intracranial, posterior eye chamber) or surgeries associated with massive bleeding and difficult hemostasis.

Representation of motor habit in a sequence of repetitive reach and grasp movements performed by macaque monkeys: evidence for a contribution of the dorsolateral prefrontal cortex.

In the context of an autologous cell transplantation study, a unilateral biopsy of cortical tissue was surgically performed from the right dorsolateral prefrontal cortex (dlPFC) in two intact adult macaque monkeys (dlPFC lesioned group), together with the implantation of a chronic chamber providing access to the left motor cortex. Three other monkeys were subjected to the same chronic chamber implantation, but without dlPFC biopsy (control group). All monkeys were initially trained to perform sequential manual dexterity tasks, requiring precision grip. The motor performance and the prehension's sequence (temporal order to grasp pellets from different spatial locations) were analysed for each hand. Following the surgery, transient and moderate deficits of manual dexterity per se occurred in both groups, indicating that they were not due to the dlPFC lesion (most likely related to the recording chamber implantation and/or general anaesthesia/medication). In contrast, changes of motor habit were observed for the sequential order of grasping in the two monkeys with dlPFC lesion only. The changes were more prominent in the monkey subjected to the largest lesion, supporting the notion of a specific effect of the dlPFC lesion on the motor habit of the monkeys. These observations are reminiscent of previous studies using conditional tasks with delay that have proposed a specialization of the dlPFC for visuo-spatial working memory, except that this is in a different context of "free-will", non-conditional manual dexterity task, without a component of working memory.