The effect of cardiac sympathetic denervation through bilateral stellate ganglionectomy on electrical properties of the heart

The role of the cardiac sympathetic nerve activity in various cardiac diseases is typically evaluated using β-adrenergic receptor antagonists. However, these antagonists induce global denervation effects not only in the cardiovascular system, but also in the brain and kidney. The objective of this study was to detect the electrophysiological property changes due to 8 days of cardiac sympathetic denervation and investigate the possible mechanisms underlying these changes using a more cardiac-specific bilateral stellate ganglionectomy (SGX) rat model. High-resolution optical mapping using a voltage-sensitive dye was performed in isolated Langendorff-perfused sham and SGX hearts, which were paced at progressively reduced basic cycle lengths under several different conditions: control, pretreatment with isoproterenol, and administration of atenolol and esmolol. Several electrophysiological parameters were recorded during periodic pacing and ventricular fibrillation (VF). Our results demonstrate that cardiac sympathetic denervation by bilateral SGX shortens action potential duration (APD) and flattens the APD restitution curve, but does not significantly affect spatial dispersion of APD. We found that, although the vulnerability of sham and SGX hearts to VF is similar, the dynamics of VF are different. The maximum dominant frequency is higher, and the spatial distribution of VF is more complex in the SGX heart, resulting in different mechanisms of VF. We demonstrated that β₁-adrenergic receptors are downregulated in the SGX compared with sham hearts. In addition, our data suggest that the mechanism of cardiac sympathetic denervation by SGX surgery is more similar to the administration of β-blocker esmolol than atenolol.