Simultaneous noninvasive recording of skin sympathetic nerve activity and electrocardiogram

Abstract

Background Sympathetic nerve activity is important to cardiac arrhythmogenesis. Objectives (1) To develop a method for simultaneous noninvasive recording of skin sympathetic nerve activity (SKNA) and electrocardiogram (ECG) using conventional ECG electrodes. (2) This method (neuECG) can be used to adequately estimate the sympathetic tone. Methods We recorded neuECG signals from the skin in 56 human subjects. The signals were low pass filtered to show the ECG and high pass filtered to show nerve activity. Protocol (P)-1 included 12 healthy volunteers who underwent cold water pressor test (CPT) and Valsalva maneuver. P-2 included 19 inpatients with epilepsy but without known heart diseases monitored for 24 hours. P-3 included 22 patients admitted with electrical storm and monitored for 39.0±28.2 hours. P-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. The SKNA recorded from chest leads (V1–V6) during CPT and Valsalva maneuver (P-1) was invariably higher than during baseline and recovery periods (p<0.001). In P-2, the average SKNA correlated with the heart rate acceleration (r=0.73±0.14, p<0.05) and shortening of the QT interval (p<0.001). Among 146 spontaneous ventricular tachycardia episodes recorded in 9 patients of P-3, 106 episodes (73%) were preceded by SKNA within 30 s of onset. P4 showed that bilateral stellate ganglia blockade by lidocaine inhibited SKNA. Conclusions SKNA is detectable using conventional ECG electrodes in humans and may be useful in estimating the sympathetic tone.

Simultaneous recordings of intrinsic cardiac nerve activity and skin sympathetic nerve activity from human patients during the postoperative period

“…The SKNA was recorded using the traditional ECG patch with the method described in a previous study. 5 The data from both channels were simultaneously digtized at 10,000 samples/s by ADI PowerLab data acquisition system and recorded continuously on a portable computer. The recording was made continuously until when the patient was discharged from the intensive care unit or at 72 hours after surgery, whichever came first.…”

“…5 We manually evaluated all recordings to exclude the periods with artifacts. We then analyzed the first 20-min of each hour to determine the activities of PVC/PAC, if any, in that time period.…”

“…4 These burst discharges were considered to precede the onset of atrial arrhythmias if they were present within 10 s prior to the onset of these arrhythmias. In addition to manual analyses, a custom-designed software was used to automatically import and to further filter the signals to display nerve activities (500–1000 Hz Band-pass filter and 100 Hz High-pass filter for ICNA and SKNA, respectively 5 ). R-wave-triggered averaging was performed in the observation window to construct an electrocardiogram (ECG) template, which was subtracted beat-by-beat in the recording to remove the ECG interference.…”

“…We recently developed a new method (neuECG) to simultaneously record the electrocardiogram (ECG) and SKNA in humans. 5 This new method enables the investigators to record the SKNA and ECG (neuECG) in patients for a prolonged period of time to study the relationship between sympathetic tone and cardiac arrhythmia. During open heart surgery, the fat pads that contain the superior left ganglionated plexi and the ligament of Marshall are readily accessible.…”

Review on Atrial Fibrillation

“…Interestingly, a group of researchers from Indiana University has elegantly demonstrated simultaneous measurements of skin sympathetic nerve activity and electrocardiogram recordings. 21 From this group, Uradu and colleagues further reported based on findings from a small group of patients that skin sympathetic nerve activity increases prior to the onset and termination of atrial tachycardia and AF. 22 This technology, though only in its infancy, has a significant potential to both predict AF noninvasively and further our understanding of atrial arrhythmias.…”