THE HEART BEAT. 551 



The Intraventricular Pressure During Systole. The best 

 analyses of the details of the systole of the ventricle have been made 

 by a study of the changes in pressure within the ventricle. For 

 this purpose a tube filled with liquid is introduced into the cavity of 

 the ventricle. A tube used for such a purpose is designated as a 

 heart-sound. For the right ventricle it is introduced through an 

 opening in the jugular vein and pushed down until it lies in the 



Fig. 230. Synchronous record of the intraventricular pressure (V), and the aortic 

 pressure (A) : S, The time record, each vibration = T^J sec. ; 0-5, corresponding ordi- 

 nates in the two curves; 1 marks the opening ot the semilunar valves; 3 (or shortly after) 

 marks the closure of these valves and the beginning of diastole. (Hiirthle.) 



ventricle, or in some cases it may be thrust through the wall of 

 the ventricle. For the left ventricle it is introduced by way of the 

 carotid or subclavian artery, or through the left auricle or ventricle. 

 The sound is then connected to a suitable recording apparatus by 

 rigid tubing filled with liquid. The changes in pressure in the 

 ventricle are extensive and very rapid. To register them accu- 

 rately the recording instrument must respond with great prompt- 

 ness and at the same time must be free from inertia movements. 

 A mercury manometer, for instance, would be entirely useless, 

 since the heavy mass of mercury could not follow accurately the 

 quick changes in pressure. The recording manometer devised 

 by Hiirthle* has been used for this purpose, as also the optically 

 recorded movements of the more accurate segment-capsule of 

 Frank (p. 498) . A typical curve obtained by means of the Hiirthle 

 manometer is given in Fig. 230, F, and two curves as obtained 

 from an optical manometer (Wiggers) in Fig. 230a. (Consult 

 also the classical curve obtained by Chauveau and Marey from the 

 heart of the horse [Fig. 220].) It will be seen that the pressure in 

 the heart rises suddenly with the beginning of the ventricular con- 

 traction, and a certain time elapses before this pressure is great 

 enough to open the semilunar valves. The moment that this occurs 

 (1, on the ventricular curve in Fig. 230) is determined by simul- 

 * Hiirthle, "Archiv f. d. gesammte Physiologie," 49, 84, 1891. 



