Cardioprotective effects of right stellate ganglion block combined with dexmedetomidine in rats with atrial fibrillation-like atrial tachyarrhythmia

Figures

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  Fig. 1. Body weight trends of rats in each group over the 7-day experimental period

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  Fig. 2. Changes in AF-like atrial tachyarrhythmia duration across groups over 7 days, analysed by repeated-measures two-way ANOVA. The y-axis represents arrhythmia duration (s)

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  Fig. 3. AF-like atrial tachyarrhythmia duration and ventricular rate on day 7 of the experiment. A Arrhythmia duration measured on day 7. B Ventricular rate on day 7. Direct SGB versus SGB + Dex comparisons showed no statistically significant difference in arrhythmia duration (p = 0.681) or ventricular rate (p = 0.137). (Data are presented as mean ± SD. Exact P values are provided where available. ****P < 0.0001 vs. AF; ***P < 0.001 vs. AF; ###P < 0.001 vs. Sham.)

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  Fig. 4. Changes in left atrial systolic and diastolic areas 7 days after tail vein injection of AF-inducing solution. A Representative transthoracic echocardiographic images and quantitative analysis of left atrial systolic area. B Representative echocardiographic images and quantitative analysis of left atrial diastolic area. Note: The SGB + Dex group is labelled as “Dex + SG” in the figure panels. (Data are presented as mean ± SD. ###P < 0.001 vs. Sham; #P < 0.05 vs. Sham; **P < 0.01 vs. AF; *P < 0.05 vs. AF.)

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  Fig. 5. Left ventricular systolic function on day 7 assessed by M-mode echocardiography. A Representative M-mode echocardiographic images obtained from the parasternal short-axis view at the papillary muscle level. B Quantitative analysis of LVEF. Note: The SGB + Dex group is labelled as “Dex + SG” in the figure panels. Direct comparison between SGB and SGB + Dex for LVEF was not statistically significant (p = 0.607). (Data are presented as mean ± SD. #P < 0.05 vs. Sham; *P < 0.05 vs. AF.)

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  Fig. 6. Atrial electrophysiological properties on day 7. The panels show (from left to right) right atrial effective refractory period (ERP), right atrial conduction time and AF-like atrial tachyarrhythmia inducibility rates by burst pacing. Direct SGB versus SGB + Dex comparisons were not statistically significant for ERP (p = 0.571), conduction time (p = 0.558) or inducibility (p = 1.000). (Data are presented as mean ± SD for continuous variables. ***P < 0.001 vs. Sham; **P < 0.01 vs. AF; *P < 0.05 vs. AF.)

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  Fig. 7. Histological evaluation of myocardial morphology by haematoxylin and eosin (HE) staining. Representative HE-stained sections of left atrial myocardium from (A) Sham, (B) AF, (C) Amiodarone (Amio), (D) Stellate ganglion block (SGB) and (E) SGB combined with dexmedetomidine (SGB + Dex) groups. Arrows indicate myofibrillar disruption/necrotic change, and asterisks indicate interstitial oedema. (Scale bar = 100 μm.)

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  Fig. 8. Assessment of myocardial fibrosis by Masson’s trichrome staining. Representative Masson-stained sections of left atrial myocardium from the (A) Sham, (B) AF, (C) Amiodarone (Amio), (D) Stellate ganglion block (SGB) and (E) SGB combined with dexmedetomidine (SGB + Dex) groups. Asterisks indicate representative collagen-rich fibrotic regions. (Scale bar = 100 μm.) (F) Quantitative analysis of collagen volume fraction (CVF) in each group. Direct comparison between SGB and SGB + Dex for CVF was not statistically significant (p = 0.477). (Data are presented as mean ± SD. ###P < 0.001 vs. Sham; **P < 0.01 vs. AF; ****P < 0.0001 vs. AF; ▲▲P < 0.01 vs. Amio.)

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  Fig. 9. Transmission electron microscopy (TEM) of left atrial myocardium in each group. Representative TEM images showing mitochondrial morphology and sarcomere ultrastructure in the (A) Sham, (B) AF, (C) Amiodarone (Amio), (D) Stellate ganglion block (SGB) and (E) SGB combined with dexmedetomidine (SGB + Dex) groups. Arrows indicate swollen or structurally disrupted mitochondria and myofibrillar disorganisation. (Scale bar = 2 μm.) (F) Quantitative analysis of mitochondrial cross-sectional area. G Percentage of morphologically abnormal mitochondria. (Data are presented as mean ± SD. *P < 0.05 vs. Sham; #P < 0.05 vs. AF.)

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  Fig. 10. Serum concentrations of IL-6 and TNF-α in each group. Serum inflammatory cytokine levels measured 7 days after AF induction. A IL-6 concentrations. B TNF-α levels. (Data are presented as mean ± SD. ###P < 0.001 vs. Sham; ***P < 0.001 vs. AF; **P < 0.01 vs. AF; *P < 0.05 vs. AF.)

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  Fig. 11. Immunofluorescence analysis of SK2 expression in the right stellate ganglion. A Representative immunofluorescence images of SK2 (red) and DAPI-stained nuclei (blue) in stellate ganglion sections from the Sham, AF, Amio, SGB and SGB + Dex groups. B Quantification of SK2 fluorescence intensity. (Data are presented as mean ± SD. #P < 0.05 vs. Sham; ****P < 0.0001 vs. AF; *P < 0.05 vs. AF; ▲P < 0.05 vs. Amio.)