ANACROTISM. 



IO9 





wave fig. 83, III, R). Here there is a true tricrotism, which is more easily obtained from the 

 carotid on account of the shortness of the arterial channel. 



2. Axillary Artery (fig. 83, IV). In this curve the ascent is very steep, while in the descent 

 near the apex there is a small (aortic) elevation, K, caused by a positive wave, produced by the 

 closure of the aortic valves. Below the middle there is a tolerably high dicrotic elevation, R, 

 higher than in the carotid curve ; because in the axillary artery the arterial tension is less, and 

 permits a greater development of the dicrotic wave. Further on, two or three small elastic 

 vibrations occur, e, e. 



3. Radial Artery (fig. 78 ; fig. 83, V to X ; fig. 93, R and Ity. The line of ascent (fig. 83) 

 is tolerably higli and sudden somewhat in the form of a long/. The apex, P, is well marked. 

 Below this, if the tension be high, two elastic vibrations may occur (V, e, e), but if it be low 

 only one (VI to IX, e). About the middle of the curve is the well-marked dicrotic elevation, 

 R. This wave is least pronounced in a small hard pulse, and when the artery is much dis- 

 tended (fig. 83, VII, R : ) ; it is larger when the tension is low (fig. 

 83, IX, R), and is greatest of all when the pulse is dicrotic (X, R). 

 Two or three small elastic elevations occur in the lowest part of 

 the curve. 



4. Femoral Artery (fig. 83, XI, XII). The ascent is steep and 

 high the apex of the curve is not unfrequently broad, and in 

 it the closure of the aortic valves (K) is indicated. The curve 

 falls rapidly towards its lowest third. The dicrotic elevation, R, 

 occurs late after the beginning of the curve, and there are also small 



(jl'iStlC slsVcltioilS (c c) 



5. Pedal Artery ('fig.' 83, XIV, XV), and Posterior Tibial (fig. 89 

 and fig. 83, XIII). In pulse-curves obtained from these arteries, 

 there are well-marked indications that the apparatus (heart) pro- 

 ducing the waves is placed at a considerable distance. The ascent 

 is oblique and low the dicrotic elevation occurs late. Two elastic 

 vibrations (fig. 83, XIV, e, e) occur in the descent, but they are very close to the apex, while 

 the elastic vibrations at the lower part of the curve are feebly marked. Fig. 89 is from the 

 posterior tibial. When measured, it gives the following result : 



( 1 to 2 . . 9-5) 



11 tO 3 . . 20 (. .. .. n.n-itfio 



<, . - oq.c ) 1 vibration is = 01613 sec. 



( 1 to 6 '. '. 61 ) 



73. ANACROTISM. As a general rule, the line of ascent of a pulse-curve has the form of an 

 /, and is nearly vertical. The arterial walls are thrown into elastic vibration by the pulse-beat, 

 and the number of vibrations depends greatly upon the tension of the arterial walls. The 

 distension of the artery, or what is the same thing, the ascent of the sphygmogram, usually 

 occurs so rapidly that it is equal to one elastic vibration. The elongated /-shape of the ascent 

 is fundamentally just a prolonged elastic vibration. When the number of vibrations causing 

 the elastic variation is small, and when the line of ascent is prolonged, two elevations occasion- 

 ally occur in the line of ascent. Such a' condition may occur normally (fig. 83, VIII, at 

 1 and 2 ; X, at 1 and 2). When a series of closely-placed elastic vibrations occur in the upper 



Fig. 89. 

 Curve of posterior tibial. 

 Written by the angio- 

 graph upon a vibrating 

 plate. 



Fig. 90. 

 Anacrotic radial curves, a, a, the anacrotic parts. 



part of the line of ascent, so that the apex appears dentate and forms an angle with the line 

 of ascent, then the condition becomes one of anacrotism (fig. 90, a, a), which, when it is so 

 marked, may be characterised as pathological. Anacrotism of the pulse occurs when the time 

 of the influx of the blood is longer than the time occupied by an elastic vibration. Hence it 

 takes place : 



(1) In dilatation and hypertrophy of the left ventricle, e.g., fig. 90, A, a tracing from the 

 radial artery of a man suffering from contracted kidney. The large volume of blood expelled 

 with each systole requires a long time to dilute the tense arteries. . 



(2) When the extensibility of the arterial wall is diminished, even the normal amount of 

 blood expelled from the heart at every systole requires a long time to dilate the artery. This 

 occurs in old people where the arteries tend to become rigid, e.g., in atheroma. Cold also 



