Simultaneous noninvasive recording of skin sympathetic nerve activity and electrocardiogram

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 (V 1 –V 6 ) during cold water pressor test and Valsalva maneuver (protocol 1) was invariably higher than during baseline and recovery periods ( P P P Conclusion SKNA is detectable using conventional ECG electrodes in humans and may be useful in estimating sympathetic tone.