298 
SURGERY AND TRANSPLANTATION 
RT. STELLATE CARDIAC 
CONTROL 
SVC TRANSECTION 
RAF 
BE(RA)-i' 
1 1 
156 
156 
Figure 2. — Regional Denervation of the Canine Heart. 
Rt. Stellate Cardiac Nerve Stimulation 
RAF = rt. atrial contractile force 
BE(RA) = bipolar electrogram, rt. atrium 
RVF = rt. ventricular contractile force 
BE (RV) rrbipolar electrogram, rt. ventricle 
sympathetic trunk required lAG dissection on 
one occasion and transection of the superior LA 
on one occasion ; right thoracic vagus nerve re- 
quired lAG dissection on two occasions; left 
thoracic vagus nerve required lAG dissection 
on two occasions and transection of the superior 
LA on two occasions; craniovagal nerve re- 
quired transection of the superior LA on two 
occasions ; and caudovagal nerve required tran- 
section of the superior LA on two occasions. 
Subsequent to these interventions, on no occa- 
sion did electrical stimulation of cardiac nerves 
result in sinus bradycardia or arrest. 
Figure 3 depicts, in control column, a decrease 
in HR from 141 to 109/minute as well as a de- 
pression in RA and LA contractility (RAF and 
LAF) during electrical stimulation of the left 
cervical vagus nerve. Following transection of 
the left SVC (column— left SVC) HR no longer 
is altered by stimulation; however, depression 
of contractile force in the RA and LA continues. 
These results indicate that parasympathetic 
fibers from this nerve reach the sinus node by 
entering along the left SVC, and further, the 
parasympathetic compon'ents to the LA and RA 
do not enter along this route. 
Atrial Innervation: Sympathetic 
Initial electrical stimulation of the following 
nerves resulted in augmentation in contractility 
in both the R A and LA in all experiments : right 
anterior ansa, right posterior ansa, left anterior 
ansa, and left posterior ansa. In contrast, stim- 
ulation of the VLCN resulted in augmentation 
of LA contractility in all animals with aug- 
mentation in the RA in 7 of 17 experiments. 
VMCN stimulation produced augmentation in 
RA in 8 of 17 experiments and augmentation in 
LA in 3 of 17. Right stellate cardiac nerve stim- 
ulation augmented contractility in the RA in 3 
experiments and in no experiments was con- 
tractility augmented in LA. Stimulation of the 
