Predictive Role of the Cervical Sympathetic Trunk Ischemia on Lower Heart Rates in an Experimentally Induced Stenoocclusive Carotid Artery Model by Bilateral Common Carotid Artery Ligation.

ABSTRACT

Bilateral common carotid artery ligation (BCCAL) leads to acute craniocervicocerebral ischemia, retrograde blood flow, increased blood pressure, and significant hemodynamic and histomorphological changes at the posterior cerebral vasculature. We examined the potential relationship between denervation injury following BCCAL-induced cervical sympathetic trunk (CST) ischemia and heart rate after permanent BCCAL. Rabbits (n = 25) were randomly divided into three groups an unoperated control group (GI, n = 6); a sham-operated control group (GII, n = 6), and an experimental group subjected to BCCAL (GIII, n = 13); and then followed for one month. All animals were then sacrificed and the stellate ganglia (STGs) were examined histologically using stereological methods. The densities of degenerated neurons in the STGs were compared with heart rates and the results were analyzed with the Mann-Whitney U test. The mean normal neuron density in STGs was 10.340 ± 954/mm3 and the degenerated neuron density was 12 ± 3/mm3 in the GI group (p > 0.5). The mean heart rates and degenerated neuron densities of STGs were recorded as 267 ± 19/min and 237 ± 45/mm3 in GII (p < 0.005 for GII vs. GI); and 190 ± 11/min 1421 ± 230/mm3 in GIII (p < 0.0001 for GIII vs. GI and p < 0.005 for GIII vs. GII). An inverse and meaningful association was observed between the heart rate and degenerated neuronal density in the STGs. BCCAL may lead to hazardous histomorphological changes in the CST. A high density of degenerated neurons in the STG may provoke excessive sympathetic hypoactivity-related cardiac damage and bradyarrhythmias after stenoocclusive carotid artery diseases.