THE PULSATORY VARIATIONS IN BLOOD PRESSURE 383 



Dudgeon and Jaquet^ have modified this instrument by adding a time marker and 

 an arrangement by means of which a narrow plate of blackened glass is moved 

 past the recording needle. But as the length of this recording surface must 

 necessarily be Umited, it does not permit of the taking of long-continued records. 

 This disadvantage is not present in those instruments which consist of a receiving 

 and a recording tambour, the former being equipped with a button-like pro- 

 jection which is placed directly over the artery.^ As the recording drum of this 

 instrument may be adjusted to a kymograph at some distance from the artery, 

 it is possible to obtain long and uninterrupted records. The so-called angiometer 

 of Hiirthle has been devised to register the pulsations of blood-vessels when fully 

 exposed to the view. The vessel itself is held in a metal groove, while a pellotte is 

 placed upon its upper border. The latter is connected with a writing lever by 

 means of a slender rod. 



Character of the Arterial Pulse Wave. Sphygmogram. — The curve 

 recorded by a sphygmograph is designated as a sphygmogram. It 



A 



Fig. 202. — The Chabacter of the Arterial Pulse. 

 AB, anacrotic limb; BC, catacrotic limb; B, apex; D, dicrotic wave; N, dicrotic 

 notch; E, predicrotic wave; F, postdi erotic waves. 



gives information regarding (a) the frequency, (6) the rhythm, 

 (c) the amphtude, and {d) the dicrotism of the pulse. Each pulsation 

 begins with an ascent which is the counterpart of the rise in systoUc 

 pressure. Furthermore, as the ventricle discharges its contents rather 

 quickly, this upstroke must necessarily be steep. The curve attains 

 its greatest height at the point of greatest distention of the artery, 

 forming here the so-called apex. It then declines slowly until the 

 following systole of the heart again sends it abruptly upward. In 

 contradistinction to the almost vertical upstroke, the downstroke 

 slants considerably, because, being opposed by a high capillary re- 

 sistance, the recoil of the distended arteries cannot give rise to a per- 

 fectly free escape of blood into the capillaries and veins. Each wave 

 of the pulse, therefore, consists essentially of two phases, its ascending 

 portion being designated as the anacrotic limb, and its descending por- 

 tion as the catacrotic limb. 



Keeping these facts clearly in mind, we are now in a position to 

 consider some of its minor details (Fig. 202). The anacrotic limb 



1 Zeitschr. fiir Biologie, xxviii, 1891. A description of the sphygmograph of 

 Petter and Frank is given in this Journal, xlix, 1907, 70. 



2 Brondgeest, Onderz, gedaan in het physiol. Lab. d. Utrecht. Derde Reeks, 

 U, 1873. 



