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.

Background-Transmyocardial laser revascularization (TMR) has been shown to improve refractory angina not amenable to conventional coronary interventions. However, the mechanism of action remains controversial, because improved myocardial perfusion has not been consistently demonstrated. We hypothesized that TMR relieves angina by causing myocardial sympathetic denervation. Methods and Results-PET imaging of resting and stress myocardial perfusion with [13 N]ammonia (NH 3 ) and of sympathetic innervation with [11 C]hydroxyephedrine (HED) was performed before and after TMR in 8 patients with class IV angina ineligible for CABG or PTCA. A mean of 50Ϯ11 channels were created in the left ventricle (LV) with a holmium:YAG laser. A semiautomated program was used to determine NH 3 uptake and HED retention in the LV. Perfusion and innervation defects were defined as the percentage of LV with tracer uptake or retention Ͼ2 SD below normal mean values. All patients experienced improvement in their angina by 2.4Ϯ0.5 angina classes after surgery, Pϭ0.008. Sympathetic innervation defects exceeded resting perfusion defects in all patients before TMR (34.6Ϯ27.3% for HED versus 9.4Ϯ10.8% for NH 3 , Pϭ0.008). TMR did not significantly affect resting or stress myocardial perfusion but increased the extent of sympathetic denervation in 6 of 8 patients by 27.5Ϯ15.9%, Pϭ0.03. In the remaining 2 patients, both sympathetic denervation and stress perfusion defects decreased after surgery. Conclusions-TMR causes decreased myocardial HED uptake in most patients without significant change in resting or stress myocardial perfusion, suggesting that the improvement in angina may be at least in part due to sympathetic denervation. (Circulation. 1999;100:135-140.)

The AFFIRM Study enrolled 4060 predominantly elderly patients with atrial fibrillation to compare ventricular rate control with rhythm control. The patients in the AFFIRM Study were representative of patients at high risk for complications from atrial fibrillation, which indicates that the results of this large clinical trial will be relevant to patient care.

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