93 



these experiments differ widely from those of simple chloro- 

 form anaesthesia as ordinarily conducted in man. It is well 

 known that in dogs morphine tends to exaggerate the con- 

 trolling influence exercised by the vagus centre over the 

 heart. 



In Laslett's^'^ well known case it was clear that vagus 

 inhibition induced repeated syncopic attacks, causing car- 

 diac standstill of the whole heart, sometimes lasting for 

 periods of six to eight seconds, but not long enough to cause 

 death ; atropine was found to be effective as a counteracting 

 agent. 



In this connexion certain observations by Sir Hugh 

 Anderson, cited by Sir Clifford Allbutt,** are very note- 

 worthy. These were on cats in which the cardiac augmentor 

 nerves were cut, by the stellate ganglia being excised some 

 time previously. It was found that swinging the animal in 

 the air caused pronounced slowing of the heart — for 

 example, from 120 down to 40 in the case of old cats.* (It 

 may be remarked that such degrees of slowing were not at 

 all dangerous, and probably did not even cause much 

 lowering of the systolic blood pressure.) But a remarkable 

 tendency to sudden death was observed in these animals. No 

 evidence is stated to show whether such deaths were actually 

 due to extraordinarily prolonged cardiac standstill, or to 

 the supervention of some other change — for example, ven- 

 tricular fibrillation, to which cats are known to be specially 

 prone under various conditions. So far as the available 

 evidence goes, there is nothing to indicate that the observed 

 slowing was more threatening to life than similar slowing 

 as seen often in common cases of non-fatal syncope in man. 



With reference to possible applications of indications 

 afforded by such experiments to the human subject it has 

 to be remarked that we know of no clinical condition in 

 man where there is reason to believe that conditions at all 

 resembling those stated above are ever present — conse- 

 quences of an interruption of the various paths that traverse 

 the stellate ganglia, loss of the nerve cells contained in them, 

 etcf Experimental investigation shows that the cardiac 

 augmentor nerves are very persistent in their action, 

 extremely resistant against drugs and various abnormal 

 conditions, and demonstrably capable of strikingly effective 

 action in many gravely depressed states of the cardiac 

 muscle — in contrast to the vagus functions, which are well 



* Sir Clifford Allbutt predicated an increased potency of the vagus in 

 old and damaged hearts. Gilbert (Arch, of Int. Med., 1923, xxxi, 423) has 

 recently found in old people a more ready response of the vagus to 

 digital compression — an age effect, apart from pathological cause. The 

 mechanism of digital pressure is undecided — whether it acts directly by 

 stimulation of efferent (inhibitory) fibres or reflexly by excitation of 

 afferent fibres. There seems to be no proof of actual danger to life in 

 this way. 



t Jonnesca's operation for angina pectoris is an example, resection of 

 the lower cervical and the first thoracic sympathetic ganglion being done 

 with the object of interrupting afferent paths from the heart. Jonnesco 

 recommends the bilateral operation, regarding it as harmless: hA does not 

 seem to have recognized any such dangers as were noted in Anderson's 

 experiments. (Jonnesco, Bull, de I'Acad. de Med., Paris, 1920, Ixxx, 93 ; 

 Presse MM., 1921, xxix, 193; Ibid., 1922, xxx, 353.) 



