| AIM: The purpose of this study was to investigate the electrophysiologic effects of extrinsic autonomic nervous on heart by stimulating rabbit cervical vagosympathetic trunk in different electrical intensity.METHODS: Ten New Zealand Rabbits were anesthetized. Body surface electrocardiograms were recorded. A 6F electrical catheter was inserted into right cardiac atrium and ventricle through right jugular vein. The atrial effective refractory period(AERP), P-wave dispersion(PD), the number of rabbits with atrial fibrillation, window of atrial vulnerability(WOV), ventrical effective refractory period(VERP), Q-T interval dispersion(Q-Td), Tpeak-Tend(Tp-e) dispersion, ventrical fibrillation threshold(VFT) were measured and recorded by means: of programmed electrical stimulation(PES). Then bilateral cervical vagosympathetic trunks were disassociated, exposed and stimulated by different intensity to reduce heart rate by 10%,30%,50% respectively. The same PES was given and same indexes were recorded.RESULTS:①Compared with the baseline, the shortening of AERP was getting significant (from 99.0±21.55 to 71.5±12.39ms; P<0.01) when the intensity of stimulating left cervical vagosympathetic trunk was increased to reduce the heart rate(HR) down by 50%. Under the same stimulating intensity, a significant change in PD was also observed (from 30.6±9.34 to 48.8±17.05ms; P<0.05) .However, no significant difference was observed in both number of rabbits with AF and WOV widening during different stimulating intensity.②Compared with the baseline, the shortening of AERP was getting significant (from 99.0±21.55 to 81.6±12.20ms; P<0.05) when the intensity of stimulating right cervical vagosympathetic trunk was increased to reduce; HR down by 30%. As the stimulating intensity was getting stronger( HR down by 50%), AERP shortening was more remarkable(from 99.0±21.55 to 69.2±14.05ms; P<0.01). A significant change in PD was also observed (from 30.6±9.34 to 42.3±10.85ms; P<0.05) when the intensity of stimulating right cervical vagosympathetic trunk was increased to make HR down by 30%. When the HR was slow down by 50%, more remarkable PD enlargement was observed(30.6±9.34 to 55.5±13.99ms; P<0.01). However, no significant difference was observed in both number of rabbits with AF and WOV widening during any stimulating intensity.③Compared with the baseline, The change of AERP was getting significant (from 99.0±21.55 to 82.0±15.35ms; P<0.05) when the intensity of stimulating bilateral cervical vagosympathetic trunks was increased to make HR down by 10%. When the stimulating intensity was increased to set HR down by 30% or 50%, more remarkable AERP shortening was observed(.P<0.01). A significant change in PD was also observed (from 30.6±9.34 to 55.0±14.79ms; P<0.05) when stimulating intensity was increased to make HR down by 30%. With increasing of stimulating intensity to set HR down by 50%, further PD enlargement was observed(from 30.6±9.34 to 64.4±18.45ms; P<0.01). And with the same stimulating intensity, the widening of WOV was getting significant (from 3.4±1.52 to 7.6±3.51ms; P<0.05). However, no significant difference was observed in number of rabbits with AF during any stimulating intensity.④Compared with the baseline, the prolongation of VERP was getting significant (from 173.7±43.00 to 209.8±40.09ms; P<0.05) when the intensity of stimulating left cervical vagosympathetic trunk was increased to make HR down by 50%. The change of Q-Td was getting significant (from 35.6±5.36 to 47.1±10.91ms; P<0.05) when stimulating intensity was increased to make HR down by 30%. With increasing of stimulating intensity to set HR down by 50%, more remarkable Q-Td enlargement was observed (from 35.6±5.36 to 54.59±14.38ms; P<0.01). The change of Tp-e dispersion was getting significant (from 21.8±5.17 to 29.9±10.62ms; P<0.05) when stimulating intensity was increased to make HR down by 30%. However, no significant change of VFT was observed during any stimulating intensity.⑤Compared with the baseline, a significant prolongation in VERP was observed (from 173.7±43.00 to 214.3±40.92ms; P<0.05) when the intensity of stimulating right cervical vagosympathetic trunk was increased to make HR down by 50%. The change of Q-Td was getting significant (from 35.6±5.36 to 48.6±7.00ms; P<0.05) when stimulating intensity was increased to make HR down by 30%. With increasing of stimulating intensity to set HR down by 50%, more remarkable Q-Td enlargement was observed (from 35.6±5.36 to 56.2±14.34ms; P<0.01).The change of Tp-e dispersion was getting extremely significant (from 21.8±5.17 to 32.8±9.91ms;P<0.01) when stimulating intensity was increased to make HR down by 30%. However, no significant change of VFT was observed during any stimulating intensity.⑥Compared with the baseline, a significant change in VERP was observed (from 173.7±43.00 to 210.6±40.35ms; P<0.05) when the intensity of stimulating bilateral cervical vagosympathetic trunks was increased to make HR down by 30%. Under the same stimulating intensity, the change of Tp-e dispersion was getting extremely significant (from 21.8±5.17 to 32.5±9.19ms;P<0.01). And with increasing of stimulating intensity to set HR down by 50%,no more remarkable of VERP prolongation and Tp-e dispersion enlargement were observed. A significant change in Q-Td was observed (from 35.6±5.36 to 44.2±6.10ms; P<0.05) when stimulating intensity was increased to make HR down by 10%. With increasing of stimulating intensity to set HR down by 50%, more remarkable Q-Td enlargement was observed (from 35.6±5.36 to 62.8±16.36ms; P<0.01). VFT showed a lowering trend, but no significant change was observed as stimulating intensity was getting stronger.CONCLUSION:①The electrophysiologic characteristics of right atrium were influenced by bilateral cervical vagosympathetic trunks in which the effects of right cervical vagosympathetic trunk was predominant. The effects of both cervical vagosympathetic trunks on electrophysiologic characteristics of right atrium showed a coordination. The electrophysiologic characteristics of right ventricle were influenced by bilateral cervical vagosympathetic trunks in which the effects of right and left cervical vagosympathetic trunk were equal. The effects of both cervical vagosympathetic trunks on electrophysiologic characteristics of right ventricle showed a coordination.②Cardiac extrinsic autonomic nervous system played an important role in changes of electrophysiologic characteristics of atrium, which may be associated with atrial arrhythmia. Cardiac extrinsic autonomic nervous system also played an important role in changes of electrophysiologic characteristics of ventricle, which may be a latent factor of ventricular arrhythmia.
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