VARIATIONS IN THE RHYTHM OF THE PULSE. 145 



VARIATIONS IN THE RHYTHM OF THE PULSE (ALLORRHYTHMIA) . 



When the finger is applied to the normal artery no special rhythm is observed, 

 the beats apparently succeeding one another at regular intervals, although small 

 differences may be observed in the intervals between the 'pulse-beats; any more 

 complicated rhythm must be considered an abnormal pulse-movement. Some- 

 times a beat is suddenly dropped from the normal succession omission of the 

 pulse. When this is due simply to weakness of the systole, the pulse is designated 

 intermittent; when due to the absence of systole, the pulse is designated deficient. 

 The latter occasionally occurs in the obese and has no pathological significance. 

 More rarely a series of pulse-beats is characterized by the successive diminution 

 of individual beats, followed after an interval by a return to the original strength 

 P. myurus. Sometimes a supernumerary pulse-beat appears to be interpolated 

 in the normal series intercurrent pulse. These forms of pulse are not infre- 

 quently produced reflexly through the gastro-intestinal tract, or they are 

 observed in cases of neurasthenia after psychical disturbances, often after intoxi- 



FIG. 52. Alternating Pulse. 



cation with alcohol or tobacco, in the absence of any changes in the heart. 

 Occasionally an intereurrent systole of the auricles takes place in conjunction with 

 the deficient or the intermittent pulse. The regular alternation from a high to a 

 low pulse is known as alternating pulse. The peculiarity of the bigeminate pulse 

 consists, according to Traube, in the circumstance that the pulse-beats always 

 occur in pairs, so that the second beat always begins close to the descending 

 limb of the curve of the first. In the same way a tr {geminate or a quadri- 

 gciuinate pulse may be produced. Knoll found in experiments on animals that 

 these varieties of the pulse occur whenever greater resistances develop in the 

 circulation, increasing the demands on the heart. In man also their occur- 

 rence points to a disproportion between the strength of the heart-muscle and the 

 work to be performed. Absolute irregularity of the heart is designated arrhythmia 

 or delirium cordis. 



VARIATIONS IN THE STRENGTH, THE TENSION, AND THE 

 VOLUME OF THE PULSE. 



The relative strength of the pulse-beat (strong and feeble pulse) may be deter- 

 mined by observing the weight the pulse is capable of raising. For this purpose 

 a weighted sphygmograph may be used, the pad of which is applied to a section 

 of the artery that must be constant in extent. The writing lever naturally ceases 

 to act as soon as the pressure on the artery exceeds the strength of the pulse- 

 beat. The load directly indicates the strength of the pulse. According to G. v. 

 Liebig the pulse in a man with a tendency to pulmonary tuberculosis is readily 

 compressed (feeble) and it has at the same time a tendency to dicrotism. 



The pulse appears hard or soft when the artery, in conformity with the 

 mean blood-pressure but independently of the strength of the individual beat, 

 offers a greater or lesser resistance to the palpating finger hard and soft pulse. 

 The pulse is said to be full when the artery is greatly distended and over- 

 filled, irrespective of the size of the pulse itself, and empty when the artery is 

 thin and poorly filled. 



In determining the tension of an artery and of the pulse, that is, whether the 

 latter is hard or soft, it should always be noted whether the artery exhibits that 

 quality only during the pulse-wave or also while the vessel is at rest. All arteries 

 are harder during the pulse-beat than in their resting state, but an artery that 

 during the pulse-beat is quite hard may during the pause between the beats appear 

 hard, or under other circumstances soft, as, for example, in cases of aortic i n - 

 io 



