Endovascular neural stimulation via a novel basket electrode catheter: Comparison of electrode configurations

We previously showed that parasympathetic stimulation by a basket electrode catheter (BEC) positioned in the superior vena cava (SVC) can slow sinus r ate (SR) or ventricular response (VR) during atrial fibrillation (AF). In 1 1 dogs, anesthetized with Na-pentobarbital, standard ECG leads II and aVR, blood pressure and right atrial electrograms were continuously monitored. T wo different BEC configurations (B1, B2) were tested in the SVC, B1 consist ed of five metal splines, each 3 cm in length. Stimulation was applied betw een adjacent splines, B2 consisted of 2 electrodes at opposite ends of each of 5 splines and a larger electrode at the middle of each spline. Stimulat ion was delivered between the two end electrodes and the middle electrode o n the same arm. Stimulation consisted of square wave stimuli, each 0.1 msec duration, frequency 20 Hz at voltages from 1-40 V, Six dogs were studied w ith B1 and five were studied with the B2 configuration. The average voltage required to produce a 50% decrease in heart rate was 22 +/- 12 V when stim ulating between adjacent splines (B1) compared to 10 +/- 5 V when stimulati ng along a single spline (B2), a 55% decrease (P less than or equal to 0.05 ), During AF, the voltage required to reduce the average ventricular rate t o 100 beats/min was 19 +/- 13 V for B1 and 8 +/- 5 V for B2, a 58% reductio n (p less than or equal to 0.05). Thus, the significant difference between B1 and B2 and in slowing SR or VR during AF was probably due to a greater c urrent density delivered with B2 to the endovascular wall and adjacent neur al elements.