Abstract
THE EFFECT OF VAGUS STIMULATION ON THE PACEMAKER Under experimental conditions, the heart rate in certain animals varies with each phase of respiration and the relationship is such that the longest diastolic pauses occur during expiration, and the shortest pauses during inspiration. Clinically, exactly similar changes in heart rate are common in children and adolescents, and in adults who are nervous or who are recovering from acute illnesses. They are increased by deep breathing and under such conditions are almost universal. The fact that these changes in heart rate disappear after atropin, or after section of the vagi in animals, demonstrates that they are vagal in origin. Recent experimental studies by Meek and Eyster1 and by Lewis, Meakins and White2 have shown that stimulation of the right vagus may cause the pacemaker to migrate from the upper to the lower portion of the sino-auricular node. Stronger stimulation

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