Background: Myocardial infarction (MI) significantly increases sympathetic tone, which is proarrhythmic. Subcutaneous nerve stimulation (SCNS) is known to cause stellate ganglion (SG) damage.
Objective: To test the hypothesis that SCNS through the left lateral thoracic nerve (LLTN) can damage the SG, suppress SG nerve activity (SGNA) and reduce cardiac nerve sprouting in ambulatory dogs with MI.
Methods: We created MI in 6 dogs and observed for 1 week. LLTN SCNS was performed between 1-10 weeks after MI while the dogs were ambulatory. Left SGNA, left lateral thoracic nerve activity (LTNA) and ECG were recorded using implanted radiotransmitters. The control included 6 dogs with chronic MI but no SCNS.
Results: The figure shows that MI increased the average SGNA (aSGNA) and the average HR (bpm). LLTN SCNS (arrow) progressively reduced aSGNA and HR in 10 weeks after MI. Immunostaining showed large confluent areas of damage in bilateral SCNS group SGs, characterized by pyknotic nuclei, reduced TH staining, and increased percentage of TH-negative ganglion cells and positive TUNEL staining. Specifically, the TH-negative cells was 15.59% in LSG and 12.70% in RSG. In control group there’s no TUNEL positive cells, while the average TUNEL positive cells in SCNS group was 26.61% in LSG and 15.94% in RSG. There were more GAP43 positive nerves in LA and LV in MI-only group than in SCNS group.
Conclusions: LLTN SCNS damaged the SG, reduced SGNA and suppressed cardiac nerve sprouting after MI.