Electroanatomic remodeling of the left stellate ganglion after myocardial infarction.

Abstract

OBJECTIVES: The purpose of this study was to evaluate the changes of left stellate ganglionic nerve activity (SGNA) and left thoracic vagal nerve activity (VNA) after acute myocardial infarction (MI). BACKGROUND: Whether MI results in remodeling of extracardiac nerve activity remains unclear. METHODS: We implanted radiotransmitters to record the SGNA, VNA, and electrocardiogram in 9 ambulatory dogs. After baseline monitoring, MI was created by 1-h balloon occlusion of the coronary arteries. The dogs were then continuously monitored for 2 months. Both stellate ganglia were stained for growth-associated protein 43 and synaptophysin. The stellate ganglia from 5 normal dogs were used as control. RESULTS: MI increased 24-h integrated SGNA from 7.44 &#xb1; 7.19 Ln(Vs)/day at baseline to 8.09 &#xb1; 7.75 Ln(Vs)/day after the MI (p < 0.05). The 24-h integrated VNA before and after the MI was 5.29 &#xb1; 5.04 Ln(Vs)/day and 5.58 &#xb1; 5.15 Ln(Vs)/day, respectively (p < 0.05). A significant 24-h circadian variation was noted for the SGNA (p < 0.05) but not the VNA. The SGNA/VNA ratio also showed significant circadian variation. The nerve densities from the left SG were 63,218 &#xb1; 34,719 &#x3bc;m(2)/mm(2) and 20,623 &#xb1; 4,926 &#x3bc;m(2)/mm(2) for growth-associated protein 43 (p < 0.05) and were 32,116 &#xb1; 8,190 &#x3bc;m(2)/mm(2)and 16,326 &#xb1; 4,679 &#x3bc;m(2)/mm(2) for synaptophysin (p < 0.05) in MI and control groups, respectively. The right SG also showed increased nerve density after MI (p < 0.05). CONCLUSIONS: MI results in persistent increase in the synaptic density of bilateral stellate ganglia and is associated with increased SGNA and VNA. There is a circadian variation of the SGNA/VNA ratio. These data indicate significant remodeling of the extracardiac autonomic nerve activity and structures after MI.