Renal Sympathetic Denervation Improves Outcomes in a Canine Myocardial Infarction Model

BACKGROUND Myocardial infarction (MI) is the main cause of heart failure (HF), and sympathetic nerve activity is associated with prognosis chronic heart failure. Renal sympathetic denervation (RDN) is noted for its powerful effect on the inhibition of sympathetic nerve activity. This study investigated the effect of RDN on heart failure in dogs after myocardial infarction. MATERIAL AND METHODS The experimental animals were randomized into 2 groups: the MI group (n=12) and the sham operation group (n=6). In the MI group we established an MI model by permanently ligating the left anterior descending branch. After 4 weeks, the MI dogs were randomly divided into 2 groups: the MI+RDN group (MI+renal sympathetic denervation, n=6) and the simple MI group (n=6). Animals in the MI+RDN group underwent both surgical and chemical renal denervation. RESULTS Compared with sham operation group, left ventricular fraction shortening (LVFS) and left ventricular ejection fraction (LVEF) were significantly reduced in the simple MI group, while the reduction was partly reversed in the MI+RDN group. RDN reduced sympathetic nerve activity and release of B-type natriuretic peptide (BNP) and Angiotensin II (AngII) in the MI+ RDN group but not in the simple MI group. CONCLUSIONS Canine renal sympathetic denervation prevents myocardial malignant remodeling by lowering the activity of the systemic sympathetic nerve and inhibiting renin-angiotensin-aldosterone system (RASS) activation, providing a new target and method for the treatment of heart failure.

Sympathetic nervous activity in patients with acute coronary syndrome: a comparative study of inflammatory biomarkers

Previous studies have shown that both sympathetic hyperactivity and enhanced inflammatory responses are associated with poor outcomes in patients with acute coronary syndrome (ACS). Whether there is a correlation between these two characteristics remains unclear. Thirty-four patients with uncomplicated ACS were evaluated; their mean age was 51.7±7.0 years, 79.4% were male, and 94.1% had myocardial infarction (MI). On the fourth day of hospitalization, they underwent muscle sympathetic nerve activity (MSNA) analysis (microneurography), as well as ultrasensitive C-reactive protein (usCRP), interleukin-6 (IL-6), and lipoprotein-associated phospholipase A2 (Lp-PLA2) activity measurements. These evaluations were repeated at 1, 3, and 6 months after hospitalization. Both MSNA and inflammatory biomarkers were elevated during the acute phase of ACS and then decreased over time. At hospitalization, the median usCRP level was 17.75 (IQR 8.57; 40.15) mg/l, the median IL-6 level was 6.65 (IQR 4.45; 8.20), the mean Lp-PLA2 activity level was 185.8 ±52.2 nmol/min per ml, and mean MSNA was 64.2±19.3 bursts/100 heart beats. All of these variables decreased significantly over 6 months compared with the in-hospital levels. MSNA was independently associated with the peak level of creatine kinase isoenzyme MB (CKMB) in the acute phase (P=0.027) and with left ventricular ejection fraction (LVEF) at 6 months (P=0.026). Despite the increased levels of inflammatory biomarkers and sympathetic hyperactivity in the initial phase of ACS, no significant correlations between them were observed in any of the analyzed phases. Our data suggest that although both sympathetic hyperactivity and inflammation are concomitantly present during the early phase of ACS, these characteristics manifest via distinct pathological pathways.