Evidence of Reduced Efferent Renal Sympathetic Innervation After Chemical Renal Denervation in Humans

Effects of renal denervation on cardiac function after percutaneous coronary intervention in patients with acute myocardial infarction

Objective

To observe the effect of renal artery denervation (RDN) on cardiac function in patients with acute myocardial infarction after percutaneous coronary intervention (AMI-PCI).

Methods

This is a single-centre, prospective randomized controlled study. A total of 108 AMI-PCI patients were randomly assigned to the RDN group or the control group at 1:1 ratio. All patients received standardized drug therapy after PCI, and patients in the RDN group underwent additional RDN at 4 weeks after the PCI. The follow-up period was 6 months after RDN. Echocardiography-derived parameters, cardiopulmonary exercise testing (CPET) data, Holter electrocardiogram, heart rate variability (HRV) at baseline and at the 6 months-follow up were analyzed.

Results

Baseline indexes were similar between the two groups (all P > 0.05). After 6 months of follow-up, the echocardiography-derived left ventricular ejection fraction was significantly higher in the RDN group than those in the control group. Cardiopulmonary exercise test indicators VO₂Max, metabolic equivalents were significantly higher in the RDN group than in the control group. HRV analysis showed that standard deviation of the normal-to-normal R-R intervals, levels of square root of the mean squared difference of successive RR intervals were significantly higher in the RDN group than those in the control group.

Conclusions

RDN intervention after PCI in AMI patients is associated with improved cardiac function, improved exercise tolerance in AMI patients post PCI. The underlying mechanism of RDN induced beneficial effects may be related to the inhibition of sympathetic nerve activity and restoration of the sympathetic-vagal balance in these patients.

Effects and mechanism of renal denervation on ventricular arrhythmia after acute myocardial infarction in rats

BACKGROUND

Renal denervation (RDN) can reduce ventricular arrhythmia after acute myocardial infarction (AMI), but the mechanism is not clear. The purpose of this study is to study its mechanism.

METHODS

Thirty-two Sprague-Dawley rats were divided into four groups: control group, AMI group, RDN-1d + AMI group, RDN-2w + AMI group. The AMI model was established 1 day after RDN in the RDN-1d + AMI group and 2 weeks after RDN in the RDN-2w + AMI group. At the same time, 8 normal rats were subjected to AMI modelling (the AMI group). The control group consisted of 8 rats without RDN intervention or AMI modelling.

RESULTS

The study confirmed that RDN can reduce the occurrence of ventricular tachycardia in AMI rats, reduce renal sympathetic nerve discharge, and inhibit the activity of local sympathetic nerves and cell growth factor (NGF) protein expression in the heart after AMI. In addition, RDN decreased the expression of norepinephrine (NE) and glutamate in the hypothalamus,and NE in cerebrospinal fluid, and increased the expression level of γ aminobutyric acid (GABA) in the hypothalamus after AMI.

CONCLUSION

RDN can effectively reduce the occurrence of ventricular arrhythmia after AMI, and its main mechanism may be via the inhibition of central sympathetic nerve discharge.

CENTRAL AND PERIPHERAL SYMPATHETIC ACTIVATION IN HEART FAILURE

The sympathetic nervous system overdrive occurring in heart failure has been reported since more than half a century. Refinements in the methodological approaches to assess human sympathetic neural function have allowed during recent years to better define various aspects related to the neuroadrenergic alteration. These include 1) the different participation of the individual regional sympathetic cardiovascular districts at the process, 2) the role of the central nervous system in determining the neuroadrenergic overdrive, 3) the involvement of baroreflex, cardiopulmonary reflex and chemoreflex mechanisms in the phoenomenon, which is also closely linked to inflammation and the immune reaction, 4) the relationships with the severity of the disease, its ischaemic or idiopathic nature and the preserved or reduced left ventricular ejection fraction and 5) the adverse functional and structural impact of the sympathetic activation on cardiovascular organs, such as the brain, the heart and the kidneys. Information have been also gained on the active role exerted by the sympathetic activation on the disease outcome and its potential relevance as target of the therapeutic interventions based on non-pharmacological, pharmacological and invasive approaches, including the renal denervation, the splanchnic sympathetic nerve ablation and the carotid baroreflex stimulation. The still undefined aspects of the neurogenic alterations and the unmet goals of the therapeutic approach having the sympathetic activation as a target of the intervention will be finally mentioned.