Selective Increase of Cardiac Neuronal Sympathetic Tone: A Catheter-Based Access to Modulate Left Ventricular Contractility Original Research Article

Objectives This study was designed to develop a technique to selectively increase the sympathetic tone to the heart by cardiac sympathetic nerve stimulation (SNS). Background Access to the cardiac sympathetic neurons may allow modulating the adrenergic tone of the heart while avoiding systemic side effects. Methods Cardiac sympathetic nerves course within neural sleeves along the subclavian artery. Because of this proximity, transvascular SNS was attempted with electrode catheters inside the subclavian artery in 16 pigs. Results Right/left (R-/L-) SNS (20 Hz) during ventricular pacing at 200/min evoked a >100% increase of left ventricular systolic pressure (baseline: 51 ± 1 mm Hg; L-SNS: 118 ± 26 mm Hg; R-SNS: 116 ± 33 mm Hg; p < 0.001) while systemic vascular resistance remained unchanged. There was a sigmoid dose-response curve with rapid on- and offset of the effect during SNS initiation/cessation. Positive inotropic effects persisted for 12 h of continued SNS (n = 4). Besides positive dromotropic effects, L-SNS/R-SNS yielded a 41% and 77% sinus rate increase, respectively. Conclusions The neural adrenergic tone to the heart can be selectively increased by catheter stimulation of cardiac efferent sympathetic nerves.