94 



A MANUAL OF PHYSIOLOGY 



It would be very unprofitable to enumerate all the sphygmographs 

 which ingenuity has invented and found names for. The first rude 

 attempt to magnify the movements of the pulse was made by loosely 

 attaching a thin fibre of glass or wax to the skin with a little lard, in 

 order to demonstrate the venous pulse which appears under certain 

 conditions. Vierordt improved on this by using a counterpoised 

 lever writing on a blackened surface. But the inertia of the lever 

 was so great that the finer features of the pulse were obscured. In 

 all modern sphygmographs there is a part, usually button-shaped, 

 which is pressed over the artery by means of a spring, as in Marey's 

 and Dudgeon's sphygmographs, or by a weight, or by a column of 

 liquid. In Marey's instrument, the button acts upon a toothed rod 

 gearing into a toothed wheel, to which a lever, or a system of levers, 



is attached. The 

 lever has a writing- 

 point which records 

 the movement on a 

 smoked plate, or a 

 plate covered with 

 smoked paper, 

 drawn uniformly 

 along by clockwork 

 (Figs. 31, 87). For 

 many clinical pur- 

 poses, especially in 

 the study of dis- 

 ordered cardiac 

 function, isolated 

 records of the ar- 

 terial pulse are of 

 comparatively little 

 value. Special 

 forms of sphygmo- 

 graphs (polygraphs) 

 have, therefore, 

 been devised, 

 which, by the ad- 

 dition of one or 

 more recording 

 tambours, permit 

 the simultaneous 

 record of move- 

 ments from two or 



more points of the vascular system for example, the radial artery 

 and the jugular vein, or the radial or carotid artery, jugular vein, 

 and the apex of the heart. In rare cases, with defect of the chest 

 wall, a tracing may be obtained even from the aorta (Fig. 33). 



In a normal arterial pulse-tracing (Fig. 32) the ascent is abrupt 

 and unbroken ; the descent is more gradual, and is interrupted 

 by one, two, or even three or more, secondary wavelets. The 

 most important and constant of these is the one marked 3, which 

 has received the name of the dicrotic wave. Usually less marked, 

 and sometimes absent, is the wavelet 2 between the dicrotic 

 elevation and the apex of the curve. It is generally termed the 



FIG. 32. PULSE-TRACINGS. 



i, primary elevation ; 2, predicrotic or first tidal 

 wave ; 3, dicrotic wave. The depression between 2 and 

 3 is the dicrotic or aortic notch ; 3 is better marked 

 in B than in A. C, dicrotic pulse with low arterial 

 pressure ; D, pulse with high arterial pressure summit 

 of primary elevation in the form of an ascending plateau. 

 E, systolic anacrotic pulse ; the secondary wavelet a 

 occurs during the upstroke corresponding to the ven- 

 tricular systole. F, presystolic anacrotic pulse ; a occurs 

 just before the systole of the ventricle. In this rarer 

 form of anacrotism, a may sometimes be due to the 

 auricular systole when the aortic valves are incompetent. 



