I08 VARIATIONS IN THE CHARACTERS OF THE PULSE. 



is a serious symptom, being frequently present when the muscular walls are degenerated.] At 

 other times the beats become smaller and smaller, and after a certain time begin as large as 

 before = p. myurus. When an extra beat is intercalated in a normal series = p. intercurrens. 



The regular alternation of a high and 

 a low beat = p. alternans (fig. 88). In 

 the p. bigeminus of Traube the beats 

 occur in pairs, so that there is a longer 

 pause after every two beats. Traube 

 T!^T^^^^^^^^^^^^^^ found that he could produce this form 

 _, . ' ' of pulse in curarised dogs by stopping 



Pulsus alternans. the artificial respiration for a long 



time. The p. trigeminus and quadrigeminus occur in the same way, but the irregularities 

 occur after every third and fourth beat. Knoll found that in animals such irregularities of the 

 pulse were apt to occur, as well as great irregularity in the rhythm generally, when there is 

 much resistance to the circulation, and consequently the heart has great demands upon its 

 energy. The same occurs in man when an improper relation exists between the force of the 

 cardiac muscle and the work it has to do (Bicgel). Complete irregularity of the heart's action 

 is railed arhythmia cordis. 



71. VARIATIONS IN THE CHARACTERS OF THE PULSE. Compressibility. The rela- 

 tive strength or compressibility of the pulse (p. fortis and debilis), i.e., whether the pulse is 

 strong or weak, is estimated by the weight which the pulse is able to raise. A sphygmograph, 

 provided with an index indicating the amount of pressure exerted upon the spring pressing upon 

 the artery, may be used (fig. 73). In this case, as soon as the pressure exerted upon the artery 

 overcomes the pulse-beat, the lever ceases to move. The weight, employed indicates the strength 

 of the pt(hr. [The linger may be, and generally is used. The finger is pressed upon the artery 

 until the pulse-beat in the artery beyond the point of pressure is obliterated. In health it re- 

 quires a pressure of several ounces to do this. Handfield Jones uses a sphygmometer for this 

 purpose. It is constructed like a cylindrical letter-weight, and the pressure is exerted by means 

 of a spiral spring which has been carefully graduated.] The pulse is hard or soft when the 

 artery, according to the mean blood-pressure, gives a feeling of greater or less resistance to the 

 linger, and this quite independent of the energy of the individual pulse-beats (p. durus and 

 mollis). In estimating the tension of the artery and the pulse, i.e., whether it is hard or soft, 

 it is important to observe whether the artery has this quality only during the pulse- wave, i.e., 

 if it is hard during diastole, or whether it is hard or soft during the period of rest of the arterial 

 wall. All arteries are harder and less compressible during the pulse-beat than during the period 

 of rest, but an artery which is very hard during the pulse-beat may be hard also during the 

 pause between the pulse-beats, or it may be very soft, as in insufficiency of the aortic valves. 

 In this case, after the systole of the left ventricle, owing to the incompetency of the aortic semi- 

 lunar valves, a largo amount of blood flows back into the ventricle, so that the arteries are 

 thereby suddenly rendered partially empty. [The sudden collapse of the artery gives rise to 

 the characteristic "pulse of unfilled arteries" (fig. 85).] 



Under similar conditions, the volume of the pulse is obvious from the size of the sphygmo- 

 gram, so that we speak of a large and a small pulse (p. magnus and parvus). Sometimes the 

 pulse is so thready and of such diminished volume that it can scarcely be felt. A large pulse 

 occurs in disease when, owing to hypertrophy of the left ventricle, a large amount of blood is 

 forced into the aorta. A small pulse occurs under the opposite condition, when a small amount 

 of blood is forced into the aorta, either from a diminution of the total amount of the blood, or 

 from the aortic orifice being narrowed [aortic stenosis], or from disease of the mitral valve ; 

 again, where the ventricle contracts feebly, the pulse becomes small and thready. 



Compare the two radials. Sometimes the pulse differs on the two sides, or it may be absent 

 on one side. [The pulse-wave in the two radials is often different when an aneurism is present 

 on one side.] 



Angiometer. Waldonburg constructed a "pulse-clock" to register the tension, the diameter 

 of the artery, and the volume of the pulse upon a dial. It does not give a graphic tracing, the 

 results being marked by the position of an indicator. 



72. THE PULSE-CURVES OF VARIOUS ARTERIES. 1. Carotid (fig. 83, I, II, III ; 

 fig. 93, C and C x ). The ascending part is very steep the apex of the curve (fig. 83, P) is sharp 

 and high. Below the apex there is a small notch the "aortic notch" (fig. 83, K) which 

 depends on a positive wave formed in the root of the aorta, owing to the closure of the aortic 

 valves, and propagated with almost wholly undiminished energy into the carotid artery. Quite 

 close to this notch, if the curve be obtained with minimal friction, the first elastic vibration 

 occurs (fig. 83, II, c). Above the middle of the descending part of the curve is the dicrotic 

 elevation, R, produced by the reflection of a positive wave from the already closed semi-lunar 

 valves. The dicrotic wave is relatively small on account of the high tension in the carotid 

 artery. After this the curve falls rapidly, but in its lowest third two small elevations may be 

 seen. Of these the former is due to elastic vibration. The latter represents a second dicrotic 



