490 CIRCULATION OF BLOOD AND LYMPH. 



Characteristics of the Pulse in Health and in Disease. 



By mere palpation the physician obtains from the pulse valuable 

 indications concerning the heart and the circulation. The fre- 

 quency of the heart beat is at once made evident, so far at least as 

 the ventricle is concerned. One may determine readily whether 

 the frequency is above or below the normal, whether the rhythm 

 is regular or irregular. By the same means one can determine 

 whether the pulse is large (pulsus magnus) or small (pulsus parvus), 

 whether the wave rises and falls rapidly (pulsus celer) as happens 

 in the case "of insufficiency of the aortic valves, or whether in one 

 phase or the other it is more prolonged than normal (pulsus tardus). 

 It seems obvious, however, that a more satisfactory conclusion may 

 be reached in all such cases by obtaining a sphygmographic record. 

 In the works devoted to clinical methods numerous such sphygmo- 

 grams are described. By mere pressure upon the artery one can 

 determine also approximately whether the blood-pressure is high 



Fig. 204. Sphygmograms illustrating the effect of variations in blood-pressure, partic- 

 V upon the position of the dicrotic wave and notch : n, The dicrotic notch ; d, the 



ularly upon the position 

 dicrotic wave. A, Sphy 

 gram with higher blood-pressure. (Mackenzie.) 



dicrotic wave. A, Sphygmogram while blood-pressure was relatively low. B, Sphygmo- 

 blood- 



or low by estimating the force with which the wave presses upon 

 the fingers, or the pressure necessary to occlude the artery. A 

 similar inference may be drawn from the character of the sphyg- 

 mogram, and especially from the relative size and position of the 

 dicrotic wave. When this latter wave falls at or near the base line 

 of the curve it indicates a low arterial pressure, since under these 

 circumstances the artery collapses readily after its first systolic 

 expansion (see Fig. 204). Since the introduction of the sphyg- 

 momanometer (p. 466), however, it seems evident that this instru- 



