VII 



MECHANICS OF THE HEART 



229 



physiological technique, and to recognise in the tracings, not 

 merely the large oscillations dependent on the respiratory move- 

 ments, but also the lesser variations due to the movements of 

 the heart. 



We found the cardiac sphygmograms obtained by the oeso- 

 phageal method to be of very complex form, varying greatly, 



Fio. 86. From same dog as preceding figure, after section of cervical cord between fifth and sixth 

 vertebrae. (Luciani.) It will be seen that diaphragmatic respiration alone persists. I, In- 

 spirations ; E, expirations. The cardiac sphygmograms are reduced to minute oscillations, 

 and are only visible on the oesophageal tracing. 



particularly in their dimensions, with the condition of the 

 animal (Figs. 85 and 86). We also found that they could not be 

 dependent exclusively on the effects of meiocardia and auxocardia, 

 but were influenced also by the nature of the relations of contact 

 between the heart and the oesophagus, since on opening the 

 thoracic cavity they do not entirely disappear, but are considerably 

 modified (Fig. 87). 



Leon Fredericq (1888) took up this point again in order to 

 make a more detailed analysis of the oesophageal sphygmograms, 

 and obtained complex forms of oscillations which closely resembled 

 the very interesting oscillations which he observed in the cavity of 



FIG. 87. Cardiac sphygmograms transmitted from oesophageal explorer during apnoea of forced 

 artificial respiration in anaesthetised dog. (Luciani.) C, With closed thorax ; A, with opened 

 thorax ; C', A', the same on another anaesthetised dog ; C", A", the same on a third curarised 

 dog. 



the auricles (see Fig. 68, p. 207). From this he concluded that 

 they were dependent on a direct transmission to the oesophagus of 

 the active and passive movements of the left auricle, pointing out 

 the intricate anatomical relations between these two organs. He 

 denied that they were in any way dependent on the effects of 

 meiocardia or auxocardia, because they are not abolished by the 

 opening of the thorax. This last conclusion, however, does not 

 take into account the fact, which we discovered twelve years 



