Studies of the arterial pulse wave.

With the technical assistance of William Urban Previous studies have shown abnormalities of the arterial pulse wave in hypertensive subjects of all age groups. The major change has been diminution to disappearance of the dicrotic wave. The pharmacologic differences between epinephrine and norepi-nephrine offer a means of studying the mechanism of this change in the dicrotic wave. In the present study, normotensive subjects have had transient hypertension induced by the infusion of epinephrine and norepinephrine. The different effects of these drugs on their arterial pulse waves have been recorded. I N A previous report,' describing observations on the arterial pulse wave in human subjects, a new technic was introduced for recording the pulse wave without intra-arterial puncture. The method has been shown to be sensitive and to give reproducible results. The accuracy of the recordings has been demonstrated by the similarity of simultaneous intra-arterial and extra-arterial tracings. Figures 1 and 2 show typical instances of normal and abnormal arterial pulse waves as recorded by this technic. The major difference in the abnormal cases appears to be diminu-tion to disappearance of the dicrotic wave. These changes in the dicrotic segment of the arterial pulse wave have been found in hyper-tensive subjects of all age groups as well as in patients with generalized arteriosclerosis, coronary arteriosclerosis, and diabetes melli-tus. The dicrotic wave has been ascribed to a reflected wave from the recoil of the blood column against the closed aortic valve. More recent studies2-7 indicate that peripheral factors also play a role in the formation of the dicrotic wave. The technic described herein seemed to offer another means of studying the mechanism of the dicrotic wave. The pharmacologic studies of Goldenberg and his group8 have shown that although both epinephrine and norepinephrine produce comparable degrees of hypertension, they do so in different ways. The hypertensive action of epinephrine in man is due primarily to a large increase in cardiac output that overbalances a decrease in total peripheral resistance. On the other hand, hypertension induced by norepinephrine is produced in man by a striking increase in peripheral resistance with little or no change in the cardiac FIG. 1. Normal arterial pulse waves recorded from the third digit of a healthy 25 year old man. The vertical lines are time signals 0.1 second apart and the horizontal lines represent pressure increments of 10 inmn. Hg in the cuff applied about the finger. The cuff …