Browsing by Subject "Stellate Ganglion"

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    Subcutaneous nerve activity is more accurate than heart rate variability in estimating cardiac sympathetic tone in ambulatory dogs with myocardial infarction
    (Elsevier, 2015-07) Chan, Yi-Hsin; Tsai, Wei-Chung; Shen, Changyu; Han, Seongwook; Chen, Lan S.; Lin, Shien-Fong; Chen, Peng-Sheng; Department of Medicine, IU School of Medicine
    BACKGROUND: We recently reported that subcutaneous nerve activity (SCNA) can be used to estimate sympathetic tone. OBJECTIVE: The purpose of this study was to test the hypothesis that left thoracic SCNA is more accurate than heart rate variability (HRV) in estimating cardiac sympathetic tone in ambulatory dogs with myocardial infarction (MI). METHODS: We used an implanted radiotransmitter to study left stellate ganglion nerve activity (SGNA), vagal nerve activity (VNA), and thoracic SCNA in 9 dogs at baseline and up to 8 weeks after MI. HRV was determined based on time-domain, frequency-domain, and nonlinear analyses. RESULTS: The correlation coefficients between integrated SGNA and SCNA averaged 0.74 (95% confidence interval [CI] 0.41-1.06) at baseline and 0.82 (95% CI, 0.63-1.01) after MI (P <.05 for both). The absolute values of the correlation coefficients were significantly larger than that between SGNA and HRV analysis based on time-domain, frequency-domain, and nonlinear analyses, respectively, at baseline (P <.05 for all) and after MI (P <.05 for all). There was a clear increment of SGNA and SCNA at 2, 4, 6, and 8 weeks after MI, whereas HRV parameters showed no significant changes. Significant circadian variations were noted in SCNA, SGNA, and all HRV parameters at baseline and after MI, respectively. Atrial tachycardia (AT) episodes were invariably preceded by SCNA and SGNA, which were progressively increased from 120th, 90th, 60th, to 30th seconds before AT onset. No such changes of HRV parameters were observed before AT onset. CONCLUSION: SCNA is more accurate than HRV in estimating cardiac sympathetic tone in ambulatory dogs with MI.
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    Using skin sympathetic nerve activity to estimate stellate ganglion nerve activity in dogs
    (Elsevier, 2015-06) Jiang, Zhaolei; Zhao, Ye; Doytchinova, Anisiia; Kamp, Nicholas J.; Tsai, Wei-Chung; Yuan, Yuan; Adams, David; Wagner, David; Shen, Changyu; Chen, Lan S.; Everett, Thomas H.; Lin, Shien-Fong; Chen, Peng-Sheng; Department of Medicine, IU School of Medicine
    BACKGROUND: Stellate ganglion nerve activity (SGNA) is important in cardiac arrhythmogenesis. However, direct recording of SGNA requires access to the thoracic cavity. Skin of upper thorax is innervated by sympathetic nerve fibers originating from the stellate ganglia and is easily accessible. OBJECTIVE: The purpose of this study was to test the hypothesis that thoracic skin nerve activity (SKNA) can be used to estimate SGNA. METHODS: We recorded SGNA and SKNAs using surface electrocardiogram leads in 5 anesthetized and 4 ambulatory dogs. Apamin injected into the right stellate ganglion abruptly increased both right SGNA and SKNA in 5 anesthetized dogs. We integrated nerve activities and averaged heart rate in each 1-minure window over 10 minutes. We implanted a radiotransmitter to record left SGNA in 4 ambulatory dogs (2 normal, 1 with myocardial infarction, 1 with intermittent rapid atrial pacing). After 2 weeks of recovery, we simultaneously recorded the SKNA and left SGNA continuously for 30 minutes when the dogs were ambulatory. RESULTS: There was a positive correlation [average r = 0.877, 95% confidence interval (CI) 0.732-1.000, P <.05 for each dog] between integrated skin nerve activity (iSKNA) and SGNA (iSGNA) and between iSKNA and heart rate (average r = 0.837, 95% CI 0.752-0.923, P <.05). Similar to that found in the anesthetized dogs, there was a positive correlation (average r = 0.746, 95% CI 0.527-0.964, P <.05) between iSKNA and iSGNA and between iSKNA and heart rate (average r = 0.706, 95% CI 0.484-0.927, P <.05). CONCLUSION: SKNAs can be used to estimate SGNA in dogs.