Browsing by Author "Shen, Mark J."

Now showing 1 - 2 of 2

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 recordings of intrinsic cardiac nerve activity and skin sympathetic nerve activity from human patients during the postoperative period
(2017-11-01)
Shen, Mark J.
;
Coffey, Arthur C.
;
Straka, Susan
;
Adams, David E.
;
Wagner, David B.
BACKGROUND Intrinsic cardiac nerve activity (ICNA) and skin nerve activity (SKNA) are both associated with cardiac arrhythmias in dogs. OBJECTIVE The purpose of this study was to test the hypothesis that ICNA and SKNA correlate with postoperative cardiac arrhythmias in humans. METHODS Eleven patients (mean age 60 6 13 years; 4 women) were enrolled in this study. Electrical signals were simultaneously recorded from electrocardiogram (ECG) patch electrodes on the chest wall and from 2 temporary pacing wires placed during open heart surgery on the left atrial epicardial fat pad. The signals were filtered to display SKNA and ICNA. Premature atrial contractions (PACs) and premature ventricular contractions were determined manually. The SKNA and ICNA of the first 300 minutes of each patient were calculated minute by minute to determine baseline average amplitudes of nerve activities and to determine their correlation with arrhythmia RESULTS We processed 1365 6 973 minutes of recording per patient. Low-amplitude SKNA and ICNA were present at all time, while the burst discharges were observed much less frequently. Both SKNA and burst ICNA were significantly associated with the onset of PACs and premature ventricular contractions. Baseline average ICNA (aICNA), but not average SKNA, had a significant association with PAC burden. The correlation coefficient (r) between aICNA and PAC burden was 0.78 (P<.01). A patient with the greatest aICNA developed postoperative atrial fibrillation. CONCLUSION ICNA and SKNA can be recorded from human patients in the postoperative period. The baseline magnitude of ICNA correlates with PAC burden and development of postoperative atrial fibrillation.