Browsing by Author "Wright, Keith C."

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Left cervical vagal nerve stimulation reduces skin sympathetic nerve activity in patients with drug resistant epilepsy
(2017-12-01)
Yuan, Yuan
;
Hassel, Jonathan L.
;
Doytchinova, Anisiia
;
Adams, David
;
Wright, Keith C.
BACKGROUND We recently reported that skin sympathetic nerve activity (SKNA) can be used to estimate sympathetic tone in humans. In animal models, vagal nerve stimulation (VNS) can damage the stellate ganglion, reduce stellate ganglion nerve activity, and suppress cardiac arrhythmia. Whether VNS can suppress sympathetic tone in humans remains unclear. OBJECTIVE The purpose of this study was to test the hypothesis that VNS suppresses SKNA in patients with drug-resistant epilepsy. METHODS ECG patch electrodes were used to continuously record SKNA in 26 patients with drug-resistant epilepsy who were admitted for video electroencephalographic monitoring. Among them, 6 (2 men, age 40 +/- 11 years) were previously treated with VNS and 20 (7 men, age 37 +/- 8 years) were not. The signals from ECG leads I and II were filtered to detect SKNA. RESULTS VNS had an on-time of 30 seconds and off-time of 158672 seconds, with output of 1.9260.42 mA at 24.17 +/- 2.01 Hz. Average SKNA during VNS off-time was 1.06 mV (95% confidence interval [CI] 0.93-1.18) in lead I and 1.13 mV (95% CI 0.99-1.27) in lead II, which was significantly lower than 1.38 mV (95% CI 1.01-1.75; P = .036) and 1.38 mV (95% CI 0.98-1.78; P = .035) in the control group, respectively. Heart rate was 65 bpm (95% CI 59-71) in the VNS group, which was significantly lower than 77 bpm (95% CI 71-83) in the control group. CONCLUSION Patients with VNS had significantly lower SKNA than those without VNS.
Skin sympathetic nerve activity precedes the onset and termination of paroxysmal atrial tachycardia and fibrillation
(2017-07-01)
Uradu, Andrea
;
Wan, Juyi
;
Doytchinova, Anisiia
;
Wright, Keith C.
;
Lin, Andrew Y. T.
BACKGROUND Skin sympathetic nerve activity (SKNA) is useful for estimating sympathetic tone in humans. OBJECTIVE The purpose of this study was to test the hypotheses that (1) increased SKNA is associated with the onset and termination of paroxysmal atrial tachycardia (AT) and atrial fibrillation (AF) and (2) sinoatrial node response to SKNA is reduced in patients with more frequent AT or AF episodes. METHODS SKNA and electrocardiogram were recorded in 11 patients (4 men and 7 women; average age 66 +/- 10 years), including 3 patients with AT (11 +/- 18 episodes per patient) and 8 patients with AF (24 +/- 26 episodes per patient). RESULTS The average SKNA (aSKNA) 10 seconds before AT onset was 1.07 +/- 0.10 mu V and 10 seconds after termination was 1.27 6 0.10 mV; both were significantly (P = .032 and P < .0001) higher than that during sinus rhythm (0.97 +/- 0.09 mu V). The aSKNA 10 seconds before AF onset was 1.34 +/- 0.07 mu V and 10 seconds after termination was 1.31 +/- 0.07 mu V; both were significantly (P < .0001) higher than that during sinus rhythm (1.04 +/- 0.07 mu V). The aSKNA before onset (P < .0001) and after termination (P < .0011) was higher in AF than in AT. The sinus rate correlated (P < .0001) with aSKNA in each patient (average r = 0.74; 95% confidence interval 0.65-0.84). The r value in each patient negatively correlated with the number of AT and AF episodes (r = -0.6493; 95% confidence interval -0.8990 to -0.08073; P = .0306). CONCLUSION Increased SKNA was observed both at the onset and termination of AT and AF. Patients with more frequent AT and AF episodes had a weak correlation between sinus rate and aSKNA, suggesting sinoatrial node remodeling by tachycardia.