1046 PHYSIOLOGY 



From time immemorial the physician has sought by feeling the 

 pulse to come to some idea as to the condition of the circulation. A 

 number of different qualities have therefore been distinguished. 

 According to the number of beats per minute the pulse is distinguished 

 as frequent or rare. The size of the pulse has reference to the amplitude 

 of excursions of each beat and the pulse is distinguished as large or 

 small. The velocity of the pulse expresses the speed with which the 

 excursion is accomplished. The quick pulse is one in which the artery 

 presses against the finger suddenly and then disappears suddenly, 

 while in the slow pulse the period during which pressure can be felt 

 is more prolonged. The hardness of the pulse is determined chiefly 

 by the blood pressure. If the pulse is compressible it is spoken of as 

 soft ; if it can only be obliterated with difficulty it is hard. Certain 

 combinations of these qualities are also described. Thus a large and 

 hard pulse is spoken of as strong, a weak pulse being both small and 

 soft. A small hard pulse is called contracted. If the rhythm of the 

 heart-beat is irregular the pulse is also irregular. An intermittent 

 pulse is one in which one heart-beat is dropped occasionally, i.e. once 

 in every four or eight beats, and may be due to the interposition of 

 a ventricular contraction which is too weak to send the pulse along so 

 far as the radial artery. 



Judgments as to the conditions of the heart and circulation from 

 the feeling of the pulse oscillations must, however, be made with 

 extreme caution. The pulse-curve may, indeed, give approximate 

 information as to the condition of things in the heart. Thus the 

 period between the beginning of the primary elevation and the di- 

 crotic notch corresponds to the outflow of blood from ventricle to aorta. 

 A large pulse-curve does not necessarily indicate a big output, since 

 the expansion of the artery is determined not only by events occurring 

 in the aorta but also by the tonus of the artery under the finger and 

 the resistance in the peripheral branches. 



Perhaps the best-marked condition of the pulse is that known as 

 the ' water-hammer ' pulse, which is observed in cases where the aortic 

 valves are injured or diseased so as to allow of regurgitation into the 

 ventricle. The systolic rise of pressure in the arterial system is followed 

 by an extremely rapid fall, so that towards the end of diastole the 

 pressure in the arteries may be insufficient to keep the arterial system 

 filled. Under such conditions, if the arm be held above the head 

 and the wrist of the patient be grasped, the pulse in the arteries 

 of the wrist is felt as a smart blow coinciding with each beat of the 

 heart. 



