One method of determining if the bursts are occurring at the same time in the cardiac cycle is to average the signal with respect to the systolic peak in the arterial pressure signal. This method was described in Guild et al. 2010. Instructions (Tech note) for how to perform this analysis in LabChart and an example LabChart data file are available for download using the links below.

Download instructions and an example data file showing how to use LabChart to determine if bursts of SNA occur in time with the arterial pulse. 

Guild et al. “Quantifying sympathetic nerve activity: problems, pitfalls and the need for standardization.“ Experimental Physiology 95(1), 41-50, 2010.