The carotid pulse. II. Relation of external recordings to carotid, aortic, and brachial pulses.

As it passes from the proximal aorta to the periphery, the normal pulse undergoes striking changes, mainly due to peripheral reflections, which result in it becoming sharper and increased in amplitude (Kroeker and Wood, 1955; McDonald and Taylor, 1959). The abnormal pulse is also subject to change, and alterations in the central pulse may, as a result, become either more or less obvious in the periphery. Thus the characteristic pulse of aortic regurgitation is made more obvious by transmission (Wright and Wood, 1958). The typical central pulse of aortic stenosis, on the other hand, may be so altered by transmission that the brachial fails to show a diagnostic pattern (Hancock and Fleming, 1960). As a result of the inadequacy of the brachial pulse in diagnosis, the carotid pulse, recorded by external means, is now increasingly used as a guide to central events (Duchosal et al., 1956; Daoud, Reppert, and Butterworth, 1959; Robinson, 1963). The present study is an attempt to assess how closely external carotid tracings reflect the central aortic pulse and in what ways they are superior to brachial pulse recordings. The relation of external carotid tracings to simultaneous carotid pressure recordings will first be established, and various types of external carotid will then be compared with the aortic and brachial pulse.