**6.5 Vagal stimulation**

Vagal nerve stimulation (VNS) is a non-pharmacological intervention to normalize autonomic imbalance, directly stimulating the vagus nerve to improve parasympathetic tone and reflex. VNS has been shown to improve left ventricular hemodynamics and increase heart rate variability. VNS also results in better vagal reflex and nitric oxide expression, improvement of the renin-angiotensin system, inflammatory cytokines modulation, reduced heart rate, risk of ventricular arrhythmias, and mortality [24]. A recent multinational, randomized clinical trial called INOVATE-HF (Increase of vagal tone in CHF) demonstrated that VNS significantly resulted in favorable effects on quality of life, NYHA functional class, and 6-min walking distance. However, the ventricular end-systolic volume index was not significantly different [25].

### **6.6 Renal denervation**

Renal efferent signals regulate renin secretion, water and sodium retention, and intrarenal vascular distribution. Efferent signals (as a response to sensory signals from renal) activate sympathetic fibers, inhibit parasympathetic fibers, and cause a release of catecholamines, which in pathology conditions such as myocardial infarction or heart failure, can increase the risk of arrhythmia [26]. Catheter-based renal denervation (RDN) is a neuromodulation treatment that includes catheter-based ablation to the renal artery wall, thus reducing the afferent and efferent sympathetic activity in the kidney and globally [26–28]. It has been used to treat drug-resistant hypertension. However, the role of RDN has also been studied as adjunctive therapy in patients with ventricular tachycardia and heart failure. By reducing circulating catecholamines, RDN reduces the electrical heterogeneity in the scarred myocardium and border zone regions and thus decreases susceptibility to ventricular arrhythmia and sudden cardiac death [26]. RDN has also been suggested to reduce blood pressure, reduce NT-proBNP, and improve NYHA class symptoms in patients with heart failure. Therefore, RDN is suggested to be favorably impactful for hypertension, MI, and heart failure [28].

### **7. Conclusion**

The heart receives extensive innervation by both sympathetic and parasympathetic systems of the ANS. The sympathetic system carries an excitatory effect on heart functions, while the parasympathetic system has inhibitory effects on heart functions. ANS abnormalities associated with electrical abnormalities can cause a variety of heart manifestations, including ventricular arrhythmias, atrial fibrillation, Long QT Syndrome, and Brugada Syndrome. Besides electrical abnormalities, ANS also correlates with ischemic heart disease. Following electrical and ischemic instability, ANS also have a direct effect on action potential duration restitution. By understanding the mechanism of influence of the anatomy and physiology of the ANS heart and its influence on various heart abnormalities, we can determine the appropriate therapeutic approaches. Therapeutic approaches in neurocardiology fall into two focuses: applying novel treatment and interaction of non-drug and multiple drugs treatments, such as selective sympathetic blockade, cardiac autonomics modulation therapies, resynchronization therapy parasympathetic function mortality and cardiovascular risk, vagal stimulation, and renal denervation.

### **Acknowledgements**

No one to acknowledge.

### **Conflict of interest**

The authors declare no conflict of interest.

*Heart Autonomic Nervous System: Basic Science and Clinical Implications DOI: http://dx.doi.org/10.5772/intechopen.101718*
