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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.

ABSTRACT: 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 <.05 for both). The absolute values of the correlation coefficients were significantly larger than that between SGNA and HRV analysis based on time-domain, frequency-domain, and nonlinear analyses, respectively, at baseline (P <.05 for all) and after MI (P <.05 for all). There was a clear increment of SGNA and SCNA at 2, 4, 6, and 8 weeks after MI, whereas HRV parameters showed no significant changes. Significant circadian variations were noted in SCNA, SGNA, and all HRV parameters at baseline and after MI, respectively. Atrial tachycardia (AT) episodes were invariably preceded by SCNA and SGNA, which were progressively increased from 120th, 90th, 60th, to 30th seconds before AT onset. No such changes of HRV parameters were observed before AT onset. CONCLUSION:SCNA is more accurate than HRV in estimating cardiac sympathetic tone in ambulatory dogs with MI.

SUBMITTER: Chan YH

PROVIDER: S-EPMC4485600 | biostudies-literature | 2015 Jul

REPOSITORIES: biostudies-literature

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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.

Chan Yi-Hsin YH Tsai Wei-Chung WC Shen Changyu C Han Seongwook S Chen Lan S LS Lin Shien-Fong SF Chen Peng-Sheng PS

Heart rhythm 20150314 7

<h4>Background</h4>We recently reported that subcutaneous nerve activity (SCNA) can be used to estimate sympathetic tone.<h4>Objective</h4>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).<h4>Methods</h4>We used an implanted radiotransmitter to study left stellate ganglion nerve activity (SGNA), vagal nerve activity (VNA), and th ...[more]

PMID: 25778433

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Project description:BackgroundLittle is known about the relationship between intrinsic cardiac nerve activity (ICNA) and spontaneous arrhythmias in ambulatory animals.Methods and resultsWe implanted radiotransmitters to record extrinsic cardiac nerve activity (ECNA; including stellate ganglion nerve activity and vagal nerve activity) and ICNA (including superior left ganglionated plexi nerve activity and ligament of Marshall nerve activity) in 6 ambulatory dogs. Intermittent rapid left atrial pacing was performed to induce paroxysmal atrial fibrillation or atrial tachycardia. The vast majority (94%) of ligament of Marshall nerve activity were preceded by or coactivated with ECNA (stellate ganglion nerve activity or vagal nerve activity), whereas 6% of episodes were activated alone without concomitant stellate ganglion nerve activity or vagal nerve activity. Paroxysmal atrial fibrillation and atrial tachycardia were invariably (100%) preceded (<5 seconds) by ICNA. Most paroxysmal atrial tachycardia events (89%) were preceded by ICNA and sympathovagal coactivation, whereas 11% were preceded by ICNA and stellate ganglion nerve activity-only activation. Most paroxysmal atrial fibrillation events were preceded only by ICNA (72%); the remaining 28% were preceded by ECNA and ICNA together. Complex fractionated atrial electrograms were observed during ICNA discharges that preceded the onset of paroxysmal atrial tachycardia and atrial fibrillation. Immunostaining confirmed the presence of both adrenergic and cholinergic nerve at ICNA sites.ConclusionsThere is a significant temporal relationship between ECNA and ICNA. However, ICNA can also activate alone. All paroxysmal atrial tachycardia and atrial fibrillation episodes were invariably preceded by ICNA. These findings suggest that ICNA (either alone or in collaboration with ECNA) is an invariable trigger of paroxysmal atrial tachyarrhythmias. ICNA might contaminate local atrial electrograms, resulting in complex fractionated atrial electrogram-like activity.

Project description:Backgrounds: Acute myocardial infarction (AMI) affects the autonomic nervous system (ANS) function. The aim of our study is to detect the particular patterns of ANS regulation in AMI. We hypothesize that altered ANS regulation in AMI patients causes synchronized neural discharge (clustering phenomenon) detected by non-invasive skin sympathetic nerve activity (SKNA). Methods: Forty subjects, including 20 AMI patients and 20 non-AMI controls, participated in the study. The wide-band bioelectrical signals (neuECG) were continuously recorded on the body surface for 5 min. SKNA was signal processed to depict the envelope of SKNA (eSKNA). By labeling the clusters, the AMI subjects were separated into non-AMI, non-cluster appearing (AMINCA), and cluster appearing (AMICA) groups. Results: The average eSKNA was significantly correlated with HRV low-frequency (LF) power (rho = -0.336) and high-frequency power (rho = -0.372). The cross-comparison results demonstrated that eSKNA is a valid surrogate marker to assess ANS in AMI patients. The frequency of cluster occurrence was 0.01-0.03 Hz and the amplitude was about 3 μV. The LF/HF ratio of AMICA (median: 1.877; Q1-Q3: 1.483-2.413) revealed significantly lower than AMINCA (median: 3.959; Q1-Q3: 1.840-6.562). The results suggest that the SKNA clustering is a unique temporal pattern of ANS synchronized discharge, which could indicate the lower sympathetic status (by HRV) in AMI patients. Conclusion: This is the first study to identify SKNA clustering phenomenon in AMI patients. Such a synchronized nerve discharge pattern could be detected with non-invasive SKNA signals. SKNA temporal clustering could be a novel biomarker to classify ANS regulation ability in AMI patients. Clinical and Translational Significance: SKNA is higher in AMI patients than in control and negatively correlates with parasympathetic parameters. SKNA clustering is associated with a lower LF/HF ratio that has been shown to correlate with sudden cardiac death in AMI. The lack of SKNA temporal clustering could indicate poor ANS regulation in AMI patients.

Dataset Information

Subcutaneous nerve activity is more accurate than heart rate variability in estimating cardiac sympathetic tone in ambulatory dogs with myocardial infarction.

Publications

Subcutaneous nerve activity is more accurate than heart rate variability in estimating cardiac sympathetic tone in ambulatory dogs with myocardial infarction.

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