THE EVENTS OF THE HUMAN CARDIAC CYCLE 77 



convenient and reliable instruments, many problems of no inconsider- 

 able clinical significance would receive elucidation. There is no 

 question that by assiduous training a clinician with keen perceptive 

 faculties may acquire great skill in timing and interpreting abnormal 

 heart sounds. Yet the dogmatism of the present day upon the sub- 

 ject of heart murmurs is entirely unjustified, a conclusion which is 

 completely borne out by the inconsistent yet equally peremptory 

 opinions of independent observers of. the same subject. Franck l in 

 a preliminary communication has recently described a new instru- 

 ment, based on the principle of the middle ear, with which graphic 

 records may be taken. Einthoven 2 has successfully used his galvano- 

 meter for the same purpose. Further results are awaited with 

 expectancy, for there is every possibility that the apparatus may 

 supply a long-felt want. 



I. THE VENTRICULAR CYCLE AND THE STANDARD MOVEMENTS 



The interpretation of the time relations of the human ventri- 

 cular movements at present 3 depends on cardiographic tracings, 

 complex curves involving changes of pressure, volume and 

 diameter in the left ventricle, and the errors emanating from 

 this method must constantly be borne in mind. It is probable 

 that the shock of the apex beat gives in thin-walled chests a 

 fair approximation oi the onset of systole, with an error which, 

 though difficult to state accurately, probably does not exceed 

 02 sec. 4 



1 Otto Franck, Milnelttner mtdiz. Woditnsdi., Bd. 51. 1904, s. 953. Weiss 

 aud Joachim (1'fliiger's Arcliiv., Bd. 123, 1908, s. 341) have more recently 

 succeeded in obtaining numerous records of heart sounds and murmurs which 

 appear to be of considerable value. 



* Pfluger'a Ardiiv., Bd. 117, 1907, s. 461. 



3 Eventually it will probably be controlled by electric curves. 



4 In one of Hlirthle's tracings (^ (Fig. 7) there is an exceptional difference 

 of -06 sec. between the upstroke of the cardiogram and the registration of the first 

 sound. In animals the tracings of Chauvcau and Marey ('), Roy and Adami ( 4I ), 

 Hiirthlt! ('*"), and most other writers show the upstroke of ventricular pressure and 

 cardiogram to be synchronous ; but such tracings are taken under exceptionally 

 favourable circumstances. 



