The Experts below are selected from a list of 9705 Experts worldwide ranked by ideXlab platform
Italo Biaggioni - One of the best experts on this subject based on the ideXlab platform.
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synergistic pressor effect of atomoxetine and pyridostigmine in patients with neurogenic orthostatic hypotension
Hypertension, 2019Co-Authors: Luis E Okamoto, Cyndya A Shibao, Alfredo Gamboa, Andre Diedrich, David Robertson, Bonnie K Black, Italo BiaggioniAbstract:Patients with autonomic failure are characterized by disabling orthostatic hypotension because of impaired Sympathetic activity, but even severely affected patients have residual Sympathetic Tone w...
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residual Sympathetic Tone is associated with reduced insulin sensitivity in patients with autonomic failure
Clinical Autonomic Research, 2015Co-Authors: Jorge E Celedonio, Luis E Okamoto, Andre Diedrich, David Robertson, Amy C Arnold, William D Dupont, Claudia E Ramirez, Satish R Raj, Amanda Peltier, Italo BiaggioniAbstract:Parkinson disease, an α-synucleinopathy, is associated with reduced insulin sensitivity, impaired glucose tolerance, and diabetes mellitus. Importantly, these metabolic alterations have been shown to contribute to disease progression. The purpose of this study was to determine if reduced insulin sensitivity is also present in other α-synucleinopathies associated with autonomic failure. We studied 19 patients with multiple system atrophy and 26 patients with pure autonomic failure. For comparison, we studied 8 healthy controls matched for body mass index. Insulin sensitivity and beta cell function were calculated using fasting glucose and insulin levels according to the homeostatic model assessment 2. A multiple linear regression model was performed to determine factors that predict insulin sensitivity in autonomic failure. There was a significant difference in insulin sensitivity among groups (P = 0.048). This difference was due to lower insulin sensitivity in multiple system atrophy patients: 64 % [interquartile range (IQR), 43 to 117] compared to healthy controls 139 % (IQR, 83 to 212), P = 0.032. The main factor that contributed to the reduced insulin sensitivity was the presence of supine hypertension and residual Sympathetic Tone. Multiple system atrophy patients have reduced insulin sensitivity that is associated with residual Sympathetic activation and supine hypertension. These patients may therefore be at high risk for development of impaired glucose tolerance and diabetes mellitus.
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comparative efficacy of yohimbine against pyridostigmine for the treatment of orthostatic hypotension in autonomic failure
Hypertension, 2010Co-Authors: Cyndya A Shibao, Luis E Okamoto, Alfredo Gamboa, Andre Diedrich, Chang Yu, David Robertson, Italo BiaggioniAbstract:Orthostatic hypotension affects patients with autonomic failure producing considerable disability because of presyncopal symptoms. Severely affected patients may have residual Sympathetic Tone that can be engaged to increase blood pressure (BP) with the α-2 adrenergic antagonist yohimbine. This medication activates Sympathetic outflow centrally and unrestrains norepinephrine release from noradrenergic neurons. Alternatively, the acetylcholinesterase inhibitor, pyridostigmine, can increase Sympathetic Tone by improving ganglionic cholinergic neurotransmission. Our purpose was to compare these complementary approaches and to explore whether the combination would lead to synergistic increases in BP. We compared the effects of 60 mg of pyridostigmine and 5.4 mg of yohimbine in a single-blind, randomized, placebo-controlled, crossover fashion. In a subset of patients we tested the combination of pyridostigmine and yohimbine. Our primary outcome was the change in standing diastolic BP 60 minutes after drug administration from baseline. We studied a total of 31 patients with severe autonomic failure. Yohimbine significantly improved standing diastolic BP as compared with placebo (11±3 mm Hg [95% CI: 6 to 16 mm Hg]; P<0.001). On the contrary, pyridostigmine did not increase the standing diastolic BP (0.6±3 mm Hg [95% CI: -5 to 5 mm Hg]; P=0.823). Only yohimbine showed a significant improvement in presyncopal symptoms. Sixteen patients received the combination of pyridostigmine and yohimbine, but no evidence of synergistic pressor effect was found. Engaging residual Sympathetic Tone with yohimbine is a more effective approach to improve orthostatic hypotension as compared with pyridostigmine in patients with severe orthostatic hypotension.
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comparative efficacy of yohimbine against pyridostigmine for the treatment of orthostatic hypotension in autonomic failure
Hypertension, 2010Co-Authors: Cyndya A Shibao, Luis E Okamoto, Alfredo Gamboa, Andre Diedrich, Chang Yu, David Robertson, Italo BiaggioniAbstract:Orthostatic hypotension affects patients with autonomic failure producing considerable disability because of presyncopal symptoms. Severely affected patients may have residual Sympathetic Tone that can be engaged to increase blood pressure (BP) with the α-2 adrenergic antagonist yohimbine. This medication activates Sympathetic outflow centrally and unrestrains norepinephrine release from noradrenergic neurons. Alternatively, the acetylcholinesterase inhibitor, pyridostigmine, can increase Sympathetic Tone by improving ganglionic cholinergic neurotransmission. Our purpose was to compare these complementary approaches and to explore whether the combination would lead to synergistic increases in BP. We compared the effects of 60 mg of pyridostigmine and 5.4 mg of yohimbine in a single-blind, randomized, placebo-controlled, crossover fashion. In a subset of patients we tested the combination of pyridostigmine and yohimbine. Our primary outcome was the change in standing diastolic BP 60 minutes after drug administration from baseline. We studied a total of 31 patients with severe autonomic failure. Yohimbine significantly improved standing diastolic BP as compared with placebo (11±3 mm Hg [95% CI: 6 to 16 mm Hg]; P P =0.823). Only yohimbine showed a significant improvement in presyncopal symptoms. Sixteen patients received the combination of pyridostigmine and yohimbine, but no evidence of synergistic pressor effect was found. Engaging residual Sympathetic Tone with yohimbine is a more effective approach to improve orthostatic hypotension as compared with pyridostigmine in patients with severe orthostatic hypotension.
Changyu Shen - One of the best experts on this subject based on the ideXlab platform.
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effects of stellate ganglion cryoablation on subcutaneous nerve activity and atrial tachyarrhythmias in a canine model of pacing induced heart failure
JACC: Clinical Electrophysiology, 2018Co-Authors: Richard S Shelton, Changyu Shen, Shien Fong Lin, Pengsheng Chen, Masahiro Ogawa, Hongbo Lin, Johnson Wong, Thomas H EverettAbstract:AbstractObjectives: This study aimed to test the hypothesis that subcutaneous nerve activity (SCNA) can adequately estimate the cardiac Sympathetic Tone and the effects of cryoablation of the stell...
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subcutaneous nerve activity and mechanisms of sudden death in a rat model of chronic kidney disease
Heart Rhythm, 2016Co-Authors: Changyu Shen, Shien Fong Lin, Ye Zhao, Neal X Chen, Jonathan T Shirazi, Michael C Fishbein, Sharon M Moe, Pengsheng ChenAbstract:Background The mechanisms of sudden death in chronic kidney disease (CKD) remain unclear. Objective The purpose of this study was to test the hypotheses that subcutaneous nerve activity (SCNA) can be used to estimate Sympathetic Tone in ambulatory rats and that abrupt reduction of SCNA precedes the spontaneous arrhythmic death of Cy/+ rats. Methods Radiotransmitters were implanted in ambulatory normal (N = 6) and Cy/+ (CKD; N=6) rats to record electrocardiogram and SCNA. Two additional rats were studied before and after chemical sympathectomy with 6-hydroxydopamine. Results In normal rats, the baseline heart rate (HR) and SCNA were 351 ± 29 bpm and 5.12 ± 2.97 mV·s, respectively. SCNA abruptly increased HR by 4.31% (95% confidence interval 4.15%–4.47%). In comparison, the CKD rats had reduced baseline HR (336 ± 21 bpm, P P P P P Conclusion SCNA can be used to estimate Sympathetic Tone in ambulatory rats. CKD is associated with reduced HR response to SCNA and conduction system diseases. Abrupt reduction of Sympathetic Tone precedes AV block, ventricular arrhythmia, and sudden death of CKD rats.
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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
PMC, 2015Co-Authors: Changyu Shen, Yi Hsin Chan, Weichung Tsai, Seongwook Han, Lan S Chen, Shien Fong LinAbstract: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 P P Conclusion SCNA is more accurate than HRV in estimating cardiac Sympathetic Tone in ambulatory dogs with MI.
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estimating Sympathetic Tone by recording subcutaneous nerve activity in ambulatory dogs
Journal of Cardiovascular Electrophysiology, 2015Co-Authors: Eric A Robinson, Kyoung Suk Rhee, Anisiia Doytchinova, Mohineesh Kumar, Richard Shelton, Zhaolei Jiang, Nicholas J Kamp, David J Adams, David Wagner, Changyu ShenAbstract:Introduction We tested the hypothesis that subcutaneous nerve activity (SCNA) of the thorax correlates with the stellate ganglion nerve activity (SGNA) and can be used to estimate the Sympathetic Tone.
Rohit Ramchandra - One of the best experts on this subject based on the ideXlab platform.
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intracranial pressure influences the level of Sympathetic Tone
American Journal of Physiology-regulatory Integrative and Comparative Physiology, 2018Co-Authors: Sarahjane Guild, Utkarsh A Saxena, Fiona D Mcbryde, Simon C Malpas, Rohit RamchandraAbstract:Sympathetic overdrive is associated with many diseases, but its origin remains an enigma. An emerging hypothesis in the development of cardiovascular disease is that the brain puts the utmost prior...
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the low frequency power of heart rate variability is neither a measure of cardiac Sympathetic Tone nor of baroreflex sensitivity
American Journal of Physiology-heart and Circulatory Physiology, 2014Co-Authors: Davide Martelli, Alessandro Silvani, Robin M Mcallen, Clive N May, Rohit RamchandraAbstract:The lack of noninvasive approaches to measure cardiac Sympathetic nerve activity (CSNA) has driven the development of indirect estimates such as the low-frequency (LF) power of heart rate variability (HRV). Recently, it has been suggested that LF HRV can be used to estimate the baroreflex modulation of heart period (HP) rather than cardiac Sympathetic Tone. To test this hypothesis, we measured CSNA, HP, blood pressure (BP), and baroreflex sensitivity (BRS) of HP, estimated with the modified Oxford technique, in conscious sheep with pacing-induced heart failure and in healthy control sheep. We found that CSNA was higher and systolic BP and HP were lower in sheep with heart failure than in control sheep. Cross-correlation analysis showed that in each group, the beat-to-beat changes in HP correlated with those in CSNA and in BP, but LF HRV did not correlate significantly with either CSNA or BRS. However, when control sheep and sheep with heart failure were considered together, CSNA correlated negatively with HP and BRS. There was also a negative correlation between CSNA and BRS in control sheep when considered alone. In conclusion, we demonstrate that in conscious sheep, LF HRV is neither a robust index of CSNA nor of BRS and is outperformed by HP and BRS in tracking CSNA. These results do not support the use of LF HRV as a noninvasive estimate of either CSNA or baroreflex function, but they highlight a link between CSNA and BRS.
Shien Fong Lin - One of the best experts on this subject based on the ideXlab platform.
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effects of stellate ganglion cryoablation on subcutaneous nerve activity and atrial tachyarrhythmias in a canine model of pacing induced heart failure
JACC: Clinical Electrophysiology, 2018Co-Authors: Richard S Shelton, Changyu Shen, Shien Fong Lin, Pengsheng Chen, Masahiro Ogawa, Hongbo Lin, Johnson Wong, Thomas H EverettAbstract:AbstractObjectives: This study aimed to test the hypothesis that subcutaneous nerve activity (SCNA) can adequately estimate the cardiac Sympathetic Tone and the effects of cryoablation of the stell...
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subcutaneous nerve activity and mechanisms of sudden death in a rat model of chronic kidney disease
Heart Rhythm, 2016Co-Authors: Changyu Shen, Shien Fong Lin, Ye Zhao, Neal X Chen, Jonathan T Shirazi, Michael C Fishbein, Sharon M Moe, Pengsheng ChenAbstract:Background The mechanisms of sudden death in chronic kidney disease (CKD) remain unclear. Objective The purpose of this study was to test the hypotheses that subcutaneous nerve activity (SCNA) can be used to estimate Sympathetic Tone in ambulatory rats and that abrupt reduction of SCNA precedes the spontaneous arrhythmic death of Cy/+ rats. Methods Radiotransmitters were implanted in ambulatory normal (N = 6) and Cy/+ (CKD; N=6) rats to record electrocardiogram and SCNA. Two additional rats were studied before and after chemical sympathectomy with 6-hydroxydopamine. Results In normal rats, the baseline heart rate (HR) and SCNA were 351 ± 29 bpm and 5.12 ± 2.97 mV·s, respectively. SCNA abruptly increased HR by 4.31% (95% confidence interval 4.15%–4.47%). In comparison, the CKD rats had reduced baseline HR (336 ± 21 bpm, P P P P P Conclusion SCNA can be used to estimate Sympathetic Tone in ambulatory rats. CKD is associated with reduced HR response to SCNA and conduction system diseases. Abrupt reduction of Sympathetic Tone precedes AV block, ventricular arrhythmia, and sudden death of CKD rats.
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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
PMC, 2015Co-Authors: Changyu Shen, Yi Hsin Chan, Weichung Tsai, Seongwook Han, Lan S Chen, Shien Fong LinAbstract: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 P P Conclusion SCNA is more accurate than HRV in estimating cardiac Sympathetic Tone in ambulatory dogs with MI.
Pengsheng Chen - One of the best experts on this subject based on the ideXlab platform.
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effects of stellate ganglion cryoablation on subcutaneous nerve activity and atrial tachyarrhythmias in a canine model of pacing induced heart failure
JACC: Clinical Electrophysiology, 2018Co-Authors: Richard S Shelton, Changyu Shen, Shien Fong Lin, Pengsheng Chen, Masahiro Ogawa, Hongbo Lin, Johnson Wong, Thomas H EverettAbstract:AbstractObjectives: This study aimed to test the hypothesis that subcutaneous nerve activity (SCNA) can adequately estimate the cardiac Sympathetic Tone and the effects of cryoablation of the stell...
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subcutaneous nerve activity and mechanisms of sudden death in a rat model of chronic kidney disease
Heart Rhythm, 2016Co-Authors: Changyu Shen, Shien Fong Lin, Ye Zhao, Neal X Chen, Jonathan T Shirazi, Michael C Fishbein, Sharon M Moe, Pengsheng ChenAbstract:Background The mechanisms of sudden death in chronic kidney disease (CKD) remain unclear. Objective The purpose of this study was to test the hypotheses that subcutaneous nerve activity (SCNA) can be used to estimate Sympathetic Tone in ambulatory rats and that abrupt reduction of SCNA precedes the spontaneous arrhythmic death of Cy/+ rats. Methods Radiotransmitters were implanted in ambulatory normal (N = 6) and Cy/+ (CKD; N=6) rats to record electrocardiogram and SCNA. Two additional rats were studied before and after chemical sympathectomy with 6-hydroxydopamine. Results In normal rats, the baseline heart rate (HR) and SCNA were 351 ± 29 bpm and 5.12 ± 2.97 mV·s, respectively. SCNA abruptly increased HR by 4.31% (95% confidence interval 4.15%–4.47%). In comparison, the CKD rats had reduced baseline HR (336 ± 21 bpm, P P P P P Conclusion SCNA can be used to estimate Sympathetic Tone in ambulatory rats. CKD is associated with reduced HR response to SCNA and conduction system diseases. Abrupt reduction of Sympathetic Tone precedes AV block, ventricular arrhythmia, and sudden death of CKD rats.
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abstract 16255 left cervical vagal nerve stimulation suppresses cardiac Sympathetic Tone
Circulation, 2015Co-Authors: Yuan Yuan, Anisiia Doytchinova, Lan S Chen, Jonathan Hassel, David H Adams, Keith Wright, Vicenta Salanova, Chad Meshberger, Thomas H Everett, Pengsheng ChenAbstract:Background: In ambulatory dogs, the left cervical vagal nerve stimulation (VNS) reduces stellate ganglion nerve activity (SGNA) and heart rate, while upper thoracic skin Sympathetic nerve activity (SKNA) has been shown to be a surrogate of SGNA to measure Sympathetic Tone. Objective: To test the hypothesis that VNS suppresses SKNA in human. Methods: We used conventional electrocardiogram (ECG) patches to continuously record SKNA in 12 patients who were admitted for video electroencephalographic monitoring. The ECG patches were placed under the right subclavian and left subclavian areas to form Lead I. The signals were band pass filtered between 200 to 1000 Hz to reveal SKNA. All antiepileptic medications were withdrawn. No patients had known organic heart diseases. No seizures occurred during the recording period. Nerve activity was quantified by integrating (iSKNA) the absolute value of the filtered signal over a 1 min window at intervals of 2 min, 20 min, and 40 min past each hour between 6 AM and 1 PM. Heart rate was determined by calculating the R-R intervals. Results: Six patients (2 men, age 40±5 years ) received chronic left cervical VNS (VNS group) and 6 (1 man, age 44±7 years) had no VNS pacing (control group). The admission diagnoses were generalized seizure (N=1) and partial seizure (N=5) in VNS group; generalized seizure (N=2) and partial seizure (N=4) in control group. The VNS pacing was continuous with an ON-time of 30 s and OFF-time of 158±72 s. The output was 1.92±0.42 mA with a frequency of 24.17±2.01 Hz. Fast Fourier Transform of the signals showed only physiologic activity between 200-1000 Hz. The iSKNA during VNS OFF-time was 13.77 mV-s [95% confidence interval, CI, 11.09 to 16.45], which was significantly lower than 20.75 mV-s [95% CI, 16.34 to 25.16, p=0.006] of the control Group. The heart rate was 67 bpm [95% CI, 60 to 74] in VNS group, significantly lower than 73 bpm [95% CI, 63 to 84] in control group. Conclusion: Patients with left cervical VNS had lower heart rate and iSKNA than patients without VNS. These findings are consistent with those observed in ambulatory canines, and suggest that chronic intermittent VNS can suppress cardiac Sympathetic Tone in human.
