Browsing by Author "Lin, Hongbo"

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Intermittent left cervical vagal nerve stimulation damages the stellate ganglia and reduces the ventricular rate during sustained atrial fibrillation in ambulatory dogs
(2016-03)
Chinda, Kroekkiat
;
Tsai, Wei-Chung
;
Chan, Yi-Hsin
;
Lin, Andrew Y-T
;
Patel, Jheel
BACKGROUND The effects of intermittent open-loop vagal nerve stimulation (VNS) on the ventricular rate (VR) during atrial fibrillation (AF) remain unclear. OBJECTIVE The purpose of this study was to test the hypothesis that VNS damages the stellate ganglion (SG) and improves VR control during persistent AF. METHODS We performed left cervical VNS in ambulatory dogs while recording the left SG nerve activity (SGNA) and vagal nerve activity. Tyrosine hydroxylase (TH) staining and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining were used to assess neuronal cell death in the SG. RESULTS We induced persistent AF by atrial pacing in 6 dogs, followed by intermittent VNS with short ON-time (14 seconds) and long OFF-time (66 seconds). The integrated SGNA and VR during AF were 4.84 mV . s (95% confidence interval [CI] 3.08-6.60 mV . s) and 142 beats/min (95% CI 116-168 beats/min), respectively. During AF, VNS reduced the integrated SGNA and VR, respectively, to 3.74 mV . s (95% CI 2.27-5.20 mV . s; P =.021) and 115 beats/ min (95% CI 96-134 beats/min; P =.016) during 66-second OFF-time and to 4.07 mV . s (95% CI 2.42-5.72 mV . s; P =.037) and 114 beats/min (95% CI 83-146 beats/min; P =.039) during 3-minute OFF-time. VNS increased the frequencies of prolonged (>3 seconds) pauses during AF. TH staining showed large confluent areas of damage in the left SG, characterized by pyknotic nuclei, reduced TH staining, increased percentage of TH-negative ganglion cells, and positive TUNEL staining. Occasional TUN EL-positive ganglion cells were also observed in the right SG. CONCLUSION VNS damaged the SG, leading to reduced SGNA and better rate control during persistent AF.
Simultaneous noninvasive recording of skin sympathetic nerve activity and electrocardiogram
(2017-01)
Doytchinova, Anisiia
;
Hassel, Jonathan L.
;
Yuan, Yuan
;
Lin, Hongbo
;
Yin, Dechun
BACKGROUND Sympathetic nerve activity is important to cardiac arrhythmogenesis. OBJECTIVE The purpose of this study was to develop a method for simultaneous noninvasive recording of skin sympathetic nerve activity (SKNA) and electrocardiogram (ECG) using conventional ECG electrodes. This method (neuECG) can be used to adequately estimate sympathetic tone. METHODS We recorded neuECG signals from the skin of 56 human subjects. The signals were low-pass filtered to show the ECG and high-pass filtered to show nerve activity. Protocol 1 included 12 healthy volunteers who underwent cold water pressor test and Valsalva maneuver. Protocol 2 included 19 inpatients with epilepsy but without known heart diseases monitored for 24 hours. Protocol 3 included 22 patients admitted with electrical storm and monitored for 39.0 +/- 28.2 hours. Protocol 4 included 3 patients who underwent bilateral stellate ganglion blockade with lidocaine injection. RESULTS In patients without heart diseases, spontaneous nerve discharges were frequently observed at baseline and were associated with heart rate acceleration. SKNA recorded from chest leads (V1V6) during cold water pressor test and Valsalva maneuver (protocol 1) was invariably higher than during baseline and recovery periods (P <.001). In protocol 2, the average SKNA correlated with heart rate acceleration (r = 0.73 +/- 0.14, P <.05) and shortening of QT interval (P <.001). Among 146 spontaneous ventricular tachycardia episodes recorded in 9 patients of protocol 3, 106 episodes (73%) were preceded by SKNA within 30 seconds of onset. Protocol 4 showed that bilateral stellate ganglia blockade by lidocaine inhibited SKNA. CONCLUSION SKNA is detectable using conventional ECG electrodes in humans and may be useful in estimating sympathetic tone.