Background: Neurogenic stunned myocardium (NSM) is a devastating complication of subarachnoid hemorrhage (SAH). The most widely accepted mechanism in the pathogenesis of NSM and takotsubo cardiomyopathy is catecholamine-mediated direct myocardial injury. The aim of this study is to examine if there is any effect of sympathetic overactivity of the stellate ganglions on myocardial tissues, secondary to vagal complex degeneration in SAH-induced NSM.
Materials and methods: This study was conducted on 25 New Zealand female rabbits. After the examination, all animals were assigned into 3 groups randomly: a control group (n = 5), a sham group (n = 5), and a study group (n = 15) that was subjected to experimental SAH with double injection of blood into the cisterna magna. After 7 animals exhibited NSM, all animals were killed. Their brains, vagal complexes, stellate ganglions, and hearts were extracted and examined by histopathologic methods. Degenerated nodose ganglion neurons and stellate ganglion neuron densities were compared with degenerated myocardial tissue/normal myocardial tissue ratios, and the results were analyzed with the Mann-Whitney U test.
Results: Three rabbits in the study group died immediately after the second injection of blood. NSM developed in 7 animals after 1 to 5 days, which was diagnosed with transthoracic echocardiography. Interestingly, the animals that developed NSM had more stellate ganglia neurons and more degenerated neuron densities of nodose ganglia (P < 0.001).
Conclusions: NSM and takotsubo cardiomyopathy may be induced by vagal complex degeneration and sympathetic overactivity, which originated from more neurons, including stellate ganglia and more degenerated neuron densities of nodose ganglia.
Keywords: Neurogenic stunned myocardium; Stunned heart and vagal complex degeneration; Takotsubo cardiomyopathy.
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