Changes in heart rate during administration of local anesthetics in neuropsychiatric patients

The effects on heart rate of injections of local anesthetics into the oral mucosa were studied in neuropsychiatric patients; these patients, in whom syncope had not occurred, had been hospitalized for a prolonged period. The heart rate in the neuropsychiatric patients decreased by only 3.9% in contrast to an average decrease of 12.6% in healthy adults. Diazepam was also effective in reducing the cardiac response. The lack of responsiveness in the trigeminal-vagal reflex may be a factor in protecting patients from syncope.