DIFFEREXCES IN THE TIME-RELATIONS OF THE PULSE. 143 



3. It is absolutely indispensable for the production of the dicrotic pulse that 

 the arterial wall possess its normal elasticity. In old persons with calcined arterial 

 walls dicrotism does not appear. 



In Fig. 51, A, B, C illustrate the gradual transition from the normal radial 

 curve (A) to the dicrotic pulse (B, C), in which the recoil-elevation (r) appears 

 as an independent elevation. 



FIG. 51. Normal Pulse-production of the Dicrotic Pulse. P. caprizans P. monocrotus. 



If in the presence of dicrotism of febrile origin the pulse becomes more and 

 more frequent, the next succeeding pulse-beat may begin before the descending 

 portion of the recoil-elevation is completed (Fig. 51, D, E, F), or it may even 

 begin at the apex (G) P. caprizans. Finally, if the next succeeding beat begins 

 in the depression (z) between the primary elevation (p) and the recoil-elevation 

 (r) , the latter disappears altogether, and the curve (H) assumes the monocrotic 

 form. 



DIFFERENCES IN THE TIME-RELATIONS OF THE PULSE. 



FREQUENT AND INFREQUENT PULSE. 



In accordance with the number of pulse-beats in one minute, the pulse is 

 designated either frequent or infrequent. Under the influence of fever or other 

 agencies the number of pulse-beats may be considerably increased until they 

 reach 120 or more. Reduction of the pulse-beats to about 40 is observed under 

 certain normal conditions (during the puerperium, in states of hunger, and as an 

 idiosyncrasy in some individuals) . In rare cases these limits may be exceeded in 

 either direction. In periodic attacks as many as 250 pulse-beats have been 

 counted. Such attacks must be designated pyknocardia (the term tachycardia is 

 incorrect because rn^i^ is equivalent to quick). Abnormal infrequency or 

 spanicardia (the term bradycardia is incorrect because fipafivf is equivalent to 

 slow) also occurs; 15, 10, and even 8 beats in the minute have been counted. 

 Under such conditions, disease of the cardiac nerves or of the muscle from over- 

 exertion or disorders in the coronary circulation should be thought of. 



Deepening of the respiration without acceleration usually causes some increase 

 in the frequency of the pulse. Accelerated but superficial' breathing is without 

 effect, while deep, rapid respirations increase the number of pulse-beats. 



QUICK AND SLOW PULSE. 



When the development of the pulse-wave is such that the distention of the 

 arterial tube goes on slowly to its maximum and collapse of the distended artery 

 likewise occurs gradually, the slow pulse is produced; while under opposite 

 conditions the quick pulse results. Among the factors that increase the quickness 

 of the pulse are: slowness of cardiac action; greatly diminished resistance of the 

 arterial coats; dilatation of the smallest arteries, diminishing the resistance to 

 the flow of blood; greater proximity to the heart. The curve in a sphygmo- 

 graphic tracing from a quick pulse is high and the apex pointed; a slow pulse 

 yields a low sphygmographic curve, the ascending portion being particularly short, 

 while the apex is broad. 



