THE PULSE. 523 



.smaller waves, such as the predicrotic, have been explained 

 simply as reflected waves, or as istrumental errors, due to fling 





"\^ 



jD [erotic 



; Wave 



Fig. 215.— Photographic reom.js of tin' Mihclaviau icfutralt i.iil.s(> .wicl the radial (per- 

 ipheral) pulse. On the subclavian pulse, ab represents u wave due to auricular B.vstole; 6c, a 

 small wave due to the rise of pressure in the ventricle before the opening of the semilunar 

 valves; cd marks the beginning of the ejection of blood into the aorta, de representing a, wave 

 due to the vibration of the column of blood. At g the pressure falls suddenly at the beginnmg 

 of diastole or relaxation of the ventricle, giving the negative wave or incisura h; k, vibrations 

 corresponding to the closure of the semilunar valves and the second heart-sound.— (From 

 Wigyers.) 



of the lever. While the dicrotic wave is due primarily to the im- 

 pulse following upon the closure of the semilunar valves, neverthe- 

 less the actual form of this and the other secondary waves is va- 

 riously modified in difl"erent parts of the system owing to imperfect 

 transmission along the extensible arteries and to the effect of 

 reflected waves from different peripheral regions, f Wiggers lays 

 stress upon the marked difference between the central pulse as 

 recorded in the arteries near the heart (subclavian and lower car- 

 otids) and the peripheral pulse as recorded in the radial. This dif- 

 ference is shown in Fig. 215, in which, as explained in the legend, 

 the subclavian pulse exhibits several significant pressure changes 

 that are lacking in the radial pulse. 



Anacrotic Waves. — As was said above, the anacrotic limb 

 under normal conditions shows no secondary waves. Under 



* For a general discussion, see Tigerstedt, " Ergebnisse d. Physiologic," 

 vol. viii, 1909, and Wiggers, "Circulation in Health and Disease," 1915. 



