STIMULATION OF THE VAGUS NERVE AND CAROTID SINUS IN MAN

¹ Surgical Clinic of Professor D. P. D. Wilkie, and the Clinical Laboratory, the Royal Infirmary, Edinburgh

The results of mechaniical stimulation of the exposed vagus nerve and carotid sinus of man in a series of twenty cases have been recorded electrocardiographically.

Of thirteen cases under ether anæsthesia, none showed any response to sinus stimulation, while one responded to vagal stimulation. Two cases under chloroform yielded responses to sinus stimulation, and one to vagal stimulation also. Of five cases under gas and oxygen, three gave responses to sinus or vagal stimulation, or to both.

The response to sinus stimulation was usually moderate bradycardia, with or without diminution of the P-waves. A different response was elicited under chloroform, consisting of the appearance of ventricular extrasystoles. Responses to vagal stimulation were similar in nature, but were characterised by a longer latent period and longer after-effect.

It has been demonstrated that the human vagus is in some cases excitable by mechanical means. The relation of this to Czermak's "vagal pressure" and to the "caroto-vagal" pressure of Hering is discussed.

The expenses of this research have been met by grants from the Moray Endowment Fund and from the Trustees of the Clinical Medicine Research Laboratory, Edinburgh Royal Infirmary.