Role of the orbital cortex in cardiac dysfunction in unanesthetized rhesus monkey

Electrocardiographic abnormalities in patients suffering from subarachnoid hemorrhage in the ventral forebrain region have been reported. The orbital cortex of the ventral forebrain plays a role in modulation of the cardiovascular system and is at present the only known cortical region to possess vagal representation. This cortical region was studied with regard to hemodynamic changes elicited by electrical stimulation, but no attempt was made to study morphologic changes in the myocardium which might occur as a result of electrical stimulation of the orbital cortex. Ten rhesus monkeys were implanted with stimulating electrodes in the orbital cortex and with aortic catheters. After recovery from the surgical instrumentation, they were stimulated in the unanesthetized, conscious state to evaluate hemodynamic responses and possible morphologic changes in the myocardium. Five of seven stimulated monkeys studied at autopsy demonstrated multifocal cardiac necrosis as a result of electrical stimulation of the orbital cortex. Three sham-operated control monkeys had normal hearts. As part of the limbic system, the orbital cortex is known to be implicated in emotional disorders, and influenced by subarachnoid hemorrhage and cerebral tumors. Our experimental results have implications for the possible role of the orbital cortex in neurogenically induced cardiopathy.