Il6 VIBRATIONS OF THE BODY DUE TO THE HEART. 



dilatation of Ou left ventricle cause the arteries near the heart to pulsate strongly. In the 

 analogous condition of the right ventricle, the beat of the pulmonary artery may be seen and felt 

 in the second left intercostal space. 



80- VIBRATIONS OF THE BODY DUE TO THE HEART. .The beating of the heart and 

 large arteries communicates vibrations to the body as a whole ; the vibration being not simple 

 but compound. Gordon was the first to represent this pulsatory vibration graphically. If a 

 person be placed in an erect attitude in the scale-pan of a large balance, the index oscillates, 

 and its movements coincide with the heart's movements. 



Method. Take a long four-sided box, K, open at the top, and arrange several coils, a, b, of 

 stout caoutchouc tubing round one end (fig. 98). A wooden board, B, is so placed that it rests 

 with one end on the caoutchouc tubing, and with the other on the narrow end of the box. The 

 j)erson to be experimented upon, A, stands vertically and firmly on this board. A receiving 

 tambour, p, is placed against the surface of the board next the elastic tube, which registers the 

 vibrations of the foot-support. Fig. III. is a curve showing such vibrations, each heart-beat 

 being followed in this case by four oscillations. To ascertain the relations and causes of these 

 vibrations, it is necessary to obtain, simultaneously, a tracing of the heart and the vibratory 

 curve. For this purpose use the two tambours of Brondgeest's pansphygmograph ( 67, 76), 

 placing one knob or pad over the heart and the other on the foot-support, and allow the writing- 

 tambours to iuscribe their vibrations on a glass plate attached to a tuning-fork. 



In the lower or cardiac impulse curve (iig. 99), the rapidly-rising part is due to the ventricular 



Fig. 99. 

 The upper curve is the vibration-curve of a healthy person, and the lower one a tracing of the 



apex-beat. 



systole. It contains eight vibrations (1 vib. =0 '01613 sec). The beginning of the ventricular 

 systole is indicated in the fig. by -36, -3, -17. 



If the corresponding numbers in the upper or vibratory curve are studied, it is obvious that 

 at the moment of ventricular systole the body makes a downward vibration, i.e., it exercises greater 

 pressure upon the foot-support. Gordon interprets his curve as giving exactly the opposite 

 result. This downward motion, however, lasted only during five vibrations of the tuning-fork : 

 during the last three vibrations, corresponding to the systole,. there is an ascent of the body 

 corresponding to a less pressure upon the foot-plate. When the ventricle empties itself, it 

 undergoes a movement in a downward and outward direction Gutbrodt's " reaction impulse." 



In the upper curve analogous numbers are employed. to indicate the vibrations occurring 

 simultaneously, viz., -28, -11, -10. The closure of the semi-lunar valves is well marked in the 

 three heart-beats at 20, -20. This closure is indicated in analogous points in both curves, after 

 which there is a descent of the foot-support, and this corresponds to the downward propagation 

 of the pulse-wave through the aorta to the vessels of the feet. 



Pathological. In insufficiency of the aortic valves, as shown in fig. 98, III., the vibration 

 communicated to the body is very considerable. 



81. THE BLOOD-CURRENT. Cause. The closed and much-branched vas- 

 cular system, whose walls are endowed with elasticity and contractility, is not only 

 completely filled with blood, but it is over-filled. The total volume of the blood 

 is somewhat greater than the capacity of the entire vascular system. Hence it 

 follows that the mass of blood must exert pressure on the walls of the entire 

 system, thus causing a corresponding dilatation of the elastic vascular walls 

 {Brunner). This occurs only during life; after death the muscles of the vessels 

 relax, and fluid passes into the tissues, so that the blood-vessels come to contain 

 less fluid, and some of them may be empty. 



