  The objective of this study was to characterize hemodynamic changes during
trans-vascular stimulation of the renal nerve and their dependence on
stimulation parameters. We employed a stimulation catheter inserted in the
right renal artery under fluoroscopic guidance, in pigs. Systolic, diastolic
and pulse blood pressure and heart rate were recorded during stimulations
delivered at different intravascular sites along the renal artery or while
varying stimulation parameters (amplitude, frequency, and pulse width). Blood
pressure changes during stimulation displayed a pattern more complex than
previously described in literature, with a series of negative and positive
peaks over the first two minutes, followed by a steady state elevation during
the remainder of the stimulation. Pulse pressure and heart rate only showed
transient responses, then they returned to baseline values despite constant
stimulation. The amplitude of the evoked hemodynamic response was roughly
linearly correlated with stimulation amplitude, frequency, and pulse width.
