THE PULSE. 



185 



the pulse, which from the indications they give or suggest of the condition 

 of the vascular system .are often of great interest. 



134. Dicrotism. In nearly all pulse-tracings, the curve of the expansion 

 and recoil of the artery is broken by two, three, or several smaller elevations 

 and depressions ; secondary waves are imposed upon the fundamental or 

 primary wave. In the sphygmographic tracing from the carotid, Fig. 68, 



FIG. 68. 



FIG, 69. 



Pulse-tracing from Carotid Artery of Healthy Man (from Moens) : x, commencement of expan- 

 sion of artery. A, summit of the first rise. C, dicrotic secondary wave. B, pre-dicrotic second- 

 ary wave ; />, notch preceding this. D, succeeding secondary wave. The curve above is that of a 

 tuning-fork with ten double vibrations in a second. 



and in many of the other tracings given, these secondary elevations are 

 marked, as B, C, D. When one such secondary elevation only is conspicu- 

 ous, so that the pulse-curve presents two notable 

 crests only, the primary crest and a secondary 

 one, the pulse is said to be " dicrotic " ; when two 

 secondary crests are prominent, the pulse is often 

 called "tricrotic"; where several, " polycrotic." 

 As a general rule, the secondary elevations appear 

 only on the descending limb of the primary wave, as 

 in most of the curves given, and the curve is then 

 spoken of as " katacrotic." Sometimes, however, 

 the first elevation or crest is not the highest, but ap- 

 pears on the ascending portion of the main curve; 

 such a curve is spoken of as " anacrotic," Fig. 69. 



Of these secondary elevations the most frequent, conspicuous, and impor- 

 tant is the one which appears some way down on the descending limb, and 

 is marked C on Fig. 68 and on most of the curves here given. It is more or 

 less distinctly visible on all sphygmograms, and may be seen in those of the 

 aorta as well as of other arteries. Sometimes it is so slight as to be hardly 

 discernible ; at other times it may be so marked as to give rise to a really 

 double pulse (Fig. 70), i. e., a pulse which can be felt as double by the 



FIG. 70. 



n 



Anacrotic Sphygmograph- 

 tracing from the Ascending 

 Aorta. (Aneurism.) 



Two Grades of Marked Dicrotism in Radial Pulse of Man. (Typhoid fever.) 



finger ; hence it has been called the dierotic elevation or the dicrotic wave, 

 the notch preceding the elevation being spoken of as the " dicrotic notch." 

 Neither it nor any other secondary elevations can be recognized in the 

 tracings of blood-pressure taken with a manometer. This may be explained, 



