350 PHYSIOLOGY OF INDUCED HYPOTHERMIA 



TABLE II 



Effect of Procaine Block of Atrial-Superior Vena Caval Area Upon Incidence of 

 Ventricular Fibrillation in Hypothermic Dogs 



(Adapted from Surgery, Nov., 1955.) 



Stimulation: Rough external manipulation or finger massage of ventricular septum 

 Untreated controls Treated (procaine block) 



A , ^ >■■ , 



Per Per 

 No. Inflow cent No. Inflow cent 

 of Temp. occlusion: fibril- of Temp. occlusion: fibril- 

 dogs range time, min. lation dogs range time. min. lation 



6 24.5-27 4.8 100 8 23.5-27.5 10.4 



Stimulation: Right ventriculotomy or right ventriculotomy and placement of sutures 

 in ventricular septum 



A . . ,^ 



6 27-28 4.2 100 11 24.6-28.3 10.4 



16 19.5-22.5 8.2 56 16 19 -22.5 10.3 6 



travenous or intra-atrial Arfonad, in sufficient amount to produce an average l^lood 

 pressure decrease from 153/11 to 60/26, was similarly effective, the incidence of 

 fibrillation being only 13 per cent. 



Bilateral section of the cervical vagosympathetic trunks, which interrupts vagal 

 but not sympathetic fibers to the heart, resulted in almost as high a percentage of 

 fibrillation as occurred in untreated control animals. On the other hand, as Mont- 

 gomery and his associates reported.® stimulation of the right vagus lowered the 

 incidence of fibrillation. If we exclude three animals in which vagal escape oc- 

 curred, fibrillation was noted in only 17 per cent. When bilateral upper dorsal sym- 

 pathectomy and stellate ganglionectomy were combined with division of the cervical 

 vagosympathetic trunks, 40 per cent of the animals developed fibrillation. The ob- 

 servation made in animals in which the vagal nerves were divided distal to the 

 caudate ganglion, and distal to the origin of the depressor nerves is difficult to 

 understand. Only 20 per cent of these animals had fibrillation. 



TABLE HI 



Effect of Extrinsic Cardiac Innervation Upon Incidence of Ventricular Fibrillation in 



Dogs Cooled to Approximately 26° to 27° C. and Subjected to Venous Inflow 



Occlusion for 10 Minutes, Right Ventriculotomy', and Placement 



OF Suture in Ventricular Septum 



(Surgery, Nov., 1955) 



No. Per cent 



Type of alteration of developing 



of nerve supply dogs fibrillation 



Bilateral upper dorsal sympathetic and stellate ganglionectdiiiy . . . 15 



Injection of intra-atrial or intravenous Arfonad 15 13 



Bilateral section of cervical vago-sympathetic trunks 15 80 



Stimulation of the right vagus 15 Z2) (entire group) 



17 (excluding 3 in 



which vagal 



escape 



occurred) 



Bilateral division of vagi distal to caudate ganglia 15 20 



Bilateral upper dorsal sympathetic and stellate ganglionectomy 



and bilateral division of cervical vago-sympathetic trunks 15 40 



