Changes of heart rate during administration of local anesthetics in the oral region.

In an attempt to clarify the mechanism of shock in dental patients, the effects on the heart rate of the injection of an anesthetic agent into the oral mucosa were studied. The heart rates of the subjects decreased by an average of 12.6% during infiltration anesthesia, which was greater than that induced by the mandibular block or breathholding. The response was completely blocked by general anesthesia and partially blocked by inhalation of nitrous oxide and oxygen or previous administration of atropine, indicating the possible participation of trigeminal-vagal reflex in producing these changes of heart rate.