MYOCARDIAL IRRITABILITY— HEGNAUER and COVINO 353 



both groups, however, would indicate that prompt restitution of cardiac function 

 after prolonged venous inflow occlusion is more important in ultimate recovery than 

 is brain perfusion. Procaine blockade and coronary artery perfusion v^ith oxy- 

 genated blood clearly permits a greatly increased period of safe caval occlusion. 

 Additional safety is derived from simultaneous carotid artery perfusion. 



Acknowledgment. Work here summarized was supported by grants from the 

 Indiana Heart Foundation and the James Whitcomb Riley Memorial Association 

 and by a contract between the Office of Naval Research, the United States Navy, 

 and Indiana University. 



REFERENCES 



1. Lian, C. : Cited in foreign letters, J.A.M.A. 155: 1367, 1954. 



2. Riberi, A., Shumacker, H. B., Jr., Kajikuri, H., Grice, P. P., and Boone, R. D. : Ventricular 



fibrillation in the hypothermic state: V. General discussion, Surgery 28: 847, 1955. 



3. Riberi, A., Syderis, H., and Shumacker, H. B. Jr. : Ventricular fibrillation in the hypothermic 



state: I. Prevention by sino-auricular node blockade, Ann. Surg. 142: 216, 1956. 



4. Radigan, L. R., Lombardo, T., and Morrow, A. G. : Prevention of ventricular fibrillation in 



experimental hypothermia : Procaine infiltration of the superior atrial-caval junction. To be 

 published. 



5. Riberi, A., Grice, P. P., and Shumacker, H. B., Jr. : Ventricular fibrillation on the hypo- 



thermic state ; II. The effect of sino-auricular node blockade in preventing ventricular 

 fibrillation at low degrees of body temperatures. Am. Surgeon 21: 1084, 1955. 



6. Montgomery, A. V., Prevedel, A. P., and Swan, H. : Prostigmine inhibition in ventricular 



fibrillation in the hypothermic dog. Circulation 10: 721, 1954. 



7. Riberi, A., Kajikuri, H., and Shumacker, H. B., Jr. : Ventricular fibrillation in the hypo- 



thermic state: III. The management of coronary air embolism and ventricular fibrillation, 

 Arch. Surg. 72: 502, 1956. 



8. Riberi, A., Shumacker, H. B., Jr., Syderis, H., and Grice, P. P. : Pxperimental repair of 



ventricular septal defects under hypothermia, Surg., Gynec. & Obst. 101: 592, 1955. 



9. Riberi, A., Grice, P. P., Rodriguez, R., Kajikuri, H., and Shumacker, H. B., Jr.: Unpub- 



lished data. 



Dr. Jean Calm: In 1953 two brief papers on the prevention of ventricular fibril- 

 lation by sino-atrial blockade appeared from our laboratory.^- - 



What we call sino-atrial blockade is the injection into the sinus node of a 1 per 

 cent solution of lignocaine ; it is very important not to replace lignocaine by pro- 

 caine, because the duration of anesthesia produced on the sinus node is longer with 

 lignocaine than with procaine. We have done experimental work on dogs and 

 monkeys with an arrest of the blood circulation longer than 25 to 30 minutes. In 

 the data reported by Dr. Shumacker the arrest of the blood circulation is not longer 

 than 15 minutes. We have proof that procaine cannot act longer than 12 to 15 

 minutes ; it is destroyed rapidly by procaine esterase. So, even though procaine 

 gives protection during the first part of the operation, ventricular fibrillation may 

 occur during the cardiac massage if the duration of the arrest of the circulation is 

 longer than 17 minutes. 



We must inject lignocaine not only in the junction area between the superior 

 vena cava and the auricle ; that is not sufficient. I could show you that it is possible 

 to stop the heart completely with an injection of lignocaine 1 per cent at the junc- 

 tion between the superior vena cava and the right auricle, but this does not avoid 

 ventricular fibrillation if the duration of the arrest is longer than 20 minutes. It is 



