Electrical Stimulation of Vascular Autonomic Nerves: Effects on Heart Rate, Blood Pressure, and Arrhythmias.

ABSTRACT

BACKGROUND: Recent clinical studies have shown conflicting results of the efficacy of renal sympathetic denervation (RSD) to mitigate hypertension. In this study, we compared electrical stimulation (ES) of autonomic nerves on the surface of the left pulmonary artery (LPA) and renal arteries (RAs) on heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure (DBP), and cardiac arrhythmias. METHODS: In 16 pentobarbital anesthetized dogs, standard electrocardiography leads and blood pressure (BP) were continuously recorded. After a left thoracotomy, a circumferential multielectrode catheter was secured around the LPA. Atrial pacing was coupled to the ES applied around the LPA during the QRS complex to avoid ventricular excitation. Flank incisions allowed retroperitoneal expose of the RAs and the aortico-renal ganglia (ARG). HR and SBP/DBP were determined at baseline (BL) and during ES of LPA, RA, or ARG. RESULTS: During ES applied to the LPA, HR was unchanged compared to BL values. In four of six animals, ventricular tachyarrhythmias were induced by ES. SBP increased significantly (BL vs ES, 129 ± 17 mm Hg vs 163 ± 21 mm Hg, P ≤ 0.05). ES applied to the RAs and ARG did not affect the HR, but significantly increased SBP/DBP (baseline 134 ± 24/96 ± 18 mm Hg; RAs stimulation 157 ± 26/114 ± 18 mm Hg; ARG stimulation 207 ± 44/147 ± 26 mm Hg, P < 0.05). CONCLUSION: ES of vascular autonomic nerves on LPA, RAs, and ARG significantly increased BP but without effects on HR. ES of ARG induced substantially greater hypertensive responses than ES of RAs, implying that ES of ARG may serve as a biomarker or ablation targets for RSD.