Cardiac sympathetic nerve stimulation and electrocardiographic changes in the closed-chest dog

Electrocardiographic changes caused by electrical stimulation of individual cardiac sym-pathetic nerves were observed with Frank's corrected orthogonal lead system and Frank's vetorcardiogram. The effects of drugs on nervous stimulation and the electrocardiographic changes after the resection of the cardiac nerves were investigated in 45 closed chest dogs. The following results were obtained: 1. The amplitude of the Twave decreased in Y lead and increased in Z lead in 20 out of 34 cases in which the right stellate ganglion [R.S.G.(A)] had been stimulated and in all cases in which the right recurrent cardiac nerve (R.Rec.C.N.) and the left ventromedial cervical cardiac nerve (L.V.M.C.N.) had been stimulated. Spatial maximum T vector displaced anteriorly and superiorly. The magnitude of spatial maximum T vector increased in all cases. 2. An increase in the amplitude of T waves in Y lead was seen in all cases in which the left stellate ganglion (L.S.G.), and the left ventrolateral cervical cardiac nerve (L.V.L.C.N.) had been stimulated, and in 14 out of 34 cases in which the right stellate ganglion [R.S.G.(B)] had been stimulated. The spatial maximum T vector was displaced inferiorly. The magnitude of the spatial maximum T vector increased in all cases. 3. The amplitude of the T wave increased in Y lead with simultaneous stimulation of both right and left stellate ganglia. The spatial maximum T vector was displaced inferiorly and the magnitude of the spatial maximum T vector increased in all cases. These electrocardiographic changes were similar to the changes which occurred with single L.S.G. stimulation. 4. Rotation of the T loop in the left saggital plane was clockwise in more than 80 % of cases with R.S.G. stimu-lation. However, rotation of the T loop in left saggital plane was counter clockwise in more than 75-80% of cases with L.S.G. and simultaneous stimulation of both right and left stellate ganglia. These results suggest that right and left cardiac sympathetic nerves innervate different myocardial areas and affect the local myocardial action potentials to cause these electrocardiographic changes. 5. In more than 40% of cases with stimulation of left cardiac sympathetic nerves (L.S.G., L.V.L.C.N.). arrythmias such as A-V dissociation and A-V junc-tional rythm were recognized. In more than 90% of cases with stimulation of right cardiac sympathetic nerves (R.S.G., R.Rec.C.N.), marked increase of sinus rythm occurred. 6. These electrocardiographic changes resulting from nervous stimulation decreased or disappeared after the use of propranolol. These results suggest that these electrocardiographic changes were caused by β -effects of catecholamines. 7. The QT ratio corrected by the formula of Bazett increased in all cases of right and left cardiac sympathetic nervous stimulation. 8. Long term observations after right or left stellate ganglionectomy revealed no significant changes in electrocardiographic patterns and a tendency to decrease in the QT ratio corrected by the formula of Bazett