Vagal afferent stimulation as a cardioprotective strategy? Introducing the concept

The effect of vagal afferent signaling on cardioinhibition has been well known for over 130 years. Both experimental and clinical studies have demonstrated not only the potential adverse effect of unrestrained sympathoexcitation in high risk patients with ischemic heart disease but the potential for cardioprotection by programmed vagal activity. The vasodepressor and negative chronotropic effects of efferent vagal stimulation has been a cause for concern. However it is becoming clear that favorable shifts towards increased cardiac vagal modulation can be achieved by vagal afferent nerve stimulation. This phasic effect appears to operate though central medullary pathways. Thus by engaging vagal afferent fibers in humans there is the possibility that one can exploit the benefits of central cardioinhibition without adversely affecting heart rate, respiration or hemodynamics. This commentary explores the background and rationale for considering vagal afferent stimulation as a plausible cardioprotective strategy.