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Cervical vagal nerve stimulation activates the stellate ganglion in ambulatory dogs.

Rhee KS, Hsueh CH, Hellyer JA, Park HW, Lee YS, Garlie J, Onkka P, Doytchinova AT, Garner JB, Patel J, Chen LS, Fishbein MC, Everett T, Lin SF, Chen PS - Korean Circ J (2015)

Bottom Line: Cervical VNS at moderate (0.75 mA) output induced large SGNA, elevated heart rate (HR), and reduced HR variability, suggesting sympathetic activation.Further increase of the VNS output to >1.5 mA increased SGNA but did not significantly increase the HR, suggesting simultaneous sympathetic and parasympathetic activation.Increasing the output may result in simultaneously sympathetic and parasympathetic capture.

View Article: PubMed Central - PubMed

Affiliation: Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA. ; Department of Internal Medicine, Chonbuk National University School of Medicine, Jeonju, Korea.

ABSTRACT

Background and objectives: Recent studies showed that, in addition to parasympathetic nerves, cervical vagal nerves contained significant sympathetic nerves. We hypothesized that cervical vagal nerve stimulation (VNS) may capture the sympathetic nerves within the vagal nerve and activate the stellate ganglion.

Materials and methods: We recorded left stellate ganglion nerve activity (SGNA), left thoracic vagal nerve activity (VNA), and subcutaneous electrocardiogram in seven dogs during left cervical VNS with 30 seconds on-time and 30 seconds off time. We then compared the SGNA between VNS on and off times.

Results: Cervical VNS at moderate (0.75 mA) output induced large SGNA, elevated heart rate (HR), and reduced HR variability, suggesting sympathetic activation. Further increase of the VNS output to >1.5 mA increased SGNA but did not significantly increase the HR, suggesting simultaneous sympathetic and parasympathetic activation. The differences of integrated SGNA and integrated VNA between VNS on and off times (ΔSGNA) increased progressively from 5.2 mV-s {95% confidence interval (CI): 1.25-9.06, p=0.018, n=7} at 1.0 mA to 13.7 mV-s (CI: 5.97-21.43, p=0.005, n=7) at 1.5 mA. The difference in HR (ΔHR, bpm) between on and off times was 5.8 bpm (CI: 0.28-11.29, p=0.042, n=7) at 1.0 mA and 5.3 bpm (CI 1.92 to 12.61, p=0.122, n=7) at 1.5 mA.

Conclusion: Intermittent cervical VNS may selectively capture the sympathetic components of the vagal nerve and excite the stellate ganglion at moderate output. Increasing the output may result in simultaneously sympathetic and parasympathetic capture.

No MeSH data available.


Related in: MedlinePlus

The SGNA, VNA, and HR of all dogs. D1 to D7 identified dogs 1 to 7, respectively. The abscissa showed the baseline (B) and the mA outputs (0.25 to 2). The SGNA from consecutive 30 seconds VNS 'on (red)' and 'off (blue) windows' for 24 hours are compared using paired t-tests. The HR responses of D3, D4, and D5 roughly followed that of the integrated SGNAs. However, in the remaining dogs, the SGNA continued to increase but the HR did not increase with the increased VNS outputs. *p<0.05. VNS: vagal nerve stimulation, SGNA: stellate ganglion nerve activity, HR: heart rate, VNA: vagal nerve activity, ECG: electrocardiogram.
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Figure 6: The SGNA, VNA, and HR of all dogs. D1 to D7 identified dogs 1 to 7, respectively. The abscissa showed the baseline (B) and the mA outputs (0.25 to 2). The SGNA from consecutive 30 seconds VNS 'on (red)' and 'off (blue) windows' for 24 hours are compared using paired t-tests. The HR responses of D3, D4, and D5 roughly followed that of the integrated SGNAs. However, in the remaining dogs, the SGNA continued to increase but the HR did not increase with the increased VNS outputs. *p<0.05. VNS: vagal nerve stimulation, SGNA: stellate ganglion nerve activity, HR: heart rate, VNA: vagal nerve activity, ECG: electrocardiogram.

Mentions: We analyzed the HR responses to VNS in each of the 7 dogs studied. Fig. 6 shows the mean SGNA, VNA, and HR at different VNS outputs in each dog studied. There was no change in the HR between 'on' and 'off' windows with a VNS output of 0.25 mA. However, when the amplitude of VNS was titrated up to 0.5 mA, 4 of 7 dogs showed a significant increase in HR. One dog (D2) showed a gradual decrease in HR when VNS output was titrated above 1.0 mA. Overall, although the differences in HR (ΔHR) between on and off windows increased with increased VNS output, the HR itself did not consistently increase with increased VNS output. Similarly, although the differences in SGNA (ΔSGNA) in general increased with increased VNS output, the SGNA itself did not consistently increase with increased VNS output. In dogs 3 and 4, the SGNA of intermediate strength (1.5 mA and 1.75 mA in Dog 3, 0.75-1.75 mA in Dog 4) appear to be lower than the SGNA of either the low output stimulus (0.5 mA) or high output stimulus (2.0 mA).


Cervical vagal nerve stimulation activates the stellate ganglion in ambulatory dogs.

Rhee KS, Hsueh CH, Hellyer JA, Park HW, Lee YS, Garlie J, Onkka P, Doytchinova AT, Garner JB, Patel J, Chen LS, Fishbein MC, Everett T, Lin SF, Chen PS - Korean Circ J (2015)

The SGNA, VNA, and HR of all dogs. D1 to D7 identified dogs 1 to 7, respectively. The abscissa showed the baseline (B) and the mA outputs (0.25 to 2). The SGNA from consecutive 30 seconds VNS 'on (red)' and 'off (blue) windows' for 24 hours are compared using paired t-tests. The HR responses of D3, D4, and D5 roughly followed that of the integrated SGNAs. However, in the remaining dogs, the SGNA continued to increase but the HR did not increase with the increased VNS outputs. *p<0.05. VNS: vagal nerve stimulation, SGNA: stellate ganglion nerve activity, HR: heart rate, VNA: vagal nerve activity, ECG: electrocardiogram.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4372981&req=5

Figure 6: The SGNA, VNA, and HR of all dogs. D1 to D7 identified dogs 1 to 7, respectively. The abscissa showed the baseline (B) and the mA outputs (0.25 to 2). The SGNA from consecutive 30 seconds VNS 'on (red)' and 'off (blue) windows' for 24 hours are compared using paired t-tests. The HR responses of D3, D4, and D5 roughly followed that of the integrated SGNAs. However, in the remaining dogs, the SGNA continued to increase but the HR did not increase with the increased VNS outputs. *p<0.05. VNS: vagal nerve stimulation, SGNA: stellate ganglion nerve activity, HR: heart rate, VNA: vagal nerve activity, ECG: electrocardiogram.
Mentions: We analyzed the HR responses to VNS in each of the 7 dogs studied. Fig. 6 shows the mean SGNA, VNA, and HR at different VNS outputs in each dog studied. There was no change in the HR between 'on' and 'off' windows with a VNS output of 0.25 mA. However, when the amplitude of VNS was titrated up to 0.5 mA, 4 of 7 dogs showed a significant increase in HR. One dog (D2) showed a gradual decrease in HR when VNS output was titrated above 1.0 mA. Overall, although the differences in HR (ΔHR) between on and off windows increased with increased VNS output, the HR itself did not consistently increase with increased VNS output. Similarly, although the differences in SGNA (ΔSGNA) in general increased with increased VNS output, the SGNA itself did not consistently increase with increased VNS output. In dogs 3 and 4, the SGNA of intermediate strength (1.5 mA and 1.75 mA in Dog 3, 0.75-1.75 mA in Dog 4) appear to be lower than the SGNA of either the low output stimulus (0.5 mA) or high output stimulus (2.0 mA).

Bottom Line: Cervical VNS at moderate (0.75 mA) output induced large SGNA, elevated heart rate (HR), and reduced HR variability, suggesting sympathetic activation.Further increase of the VNS output to >1.5 mA increased SGNA but did not significantly increase the HR, suggesting simultaneous sympathetic and parasympathetic activation.Increasing the output may result in simultaneously sympathetic and parasympathetic capture.

View Article: PubMed Central - PubMed

Affiliation: Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA. ; Department of Internal Medicine, Chonbuk National University School of Medicine, Jeonju, Korea.

ABSTRACT

Background and objectives: Recent studies showed that, in addition to parasympathetic nerves, cervical vagal nerves contained significant sympathetic nerves. We hypothesized that cervical vagal nerve stimulation (VNS) may capture the sympathetic nerves within the vagal nerve and activate the stellate ganglion.

Materials and methods: We recorded left stellate ganglion nerve activity (SGNA), left thoracic vagal nerve activity (VNA), and subcutaneous electrocardiogram in seven dogs during left cervical VNS with 30 seconds on-time and 30 seconds off time. We then compared the SGNA between VNS on and off times.

Results: Cervical VNS at moderate (0.75 mA) output induced large SGNA, elevated heart rate (HR), and reduced HR variability, suggesting sympathetic activation. Further increase of the VNS output to >1.5 mA increased SGNA but did not significantly increase the HR, suggesting simultaneous sympathetic and parasympathetic activation. The differences of integrated SGNA and integrated VNA between VNS on and off times (ΔSGNA) increased progressively from 5.2 mV-s {95% confidence interval (CI): 1.25-9.06, p=0.018, n=7} at 1.0 mA to 13.7 mV-s (CI: 5.97-21.43, p=0.005, n=7) at 1.5 mA. The difference in HR (ΔHR, bpm) between on and off times was 5.8 bpm (CI: 0.28-11.29, p=0.042, n=7) at 1.0 mA and 5.3 bpm (CI 1.92 to 12.61, p=0.122, n=7) at 1.5 mA.

Conclusion: Intermittent cervical VNS may selectively capture the sympathetic components of the vagal nerve and excite the stellate ganglion at moderate output. Increasing the output may result in simultaneously sympathetic and parasympathetic capture.

No MeSH data available.


Related in: MedlinePlus