July 12, 2012Open Access
View Full PaperEffect of Bipolar Electrode Spacing on Phrenic Nerve Stimulation and Left Ventricular Pacing Thresholds
Key Result
Reducing LV bipolar electrode spacing to 1 mm or 2 mm significantly increased the phrenic nerve stimulation threshold by 5.5±2.2 V (P=0.003) and 2.8±1.7 V (P<0.001) compared with 20 mm spacing.
Study Design
Type
RCT (n=6)
Randomization
Randomized order
Structured PICO
Does reducing bipolar electrode spacing increase phrenic nerve stimulation thresholds without compromising LV pacing thresholds in a canine model?
P
Population
6 anesthetized dogs undergoing evaluation of bipolar electrode spacing on phrenic nerve stimulation and left ventricular pacing thresholds.
I
Intervention
Reduced bipolar electrode spacing (1 mm and 2 mm)
C
Comparator
Standard bipolar electrode spacing (20 mm) and unipolar pacing
O
Outcome
Phrenic nerve stimulation (PNS) threshold and left ventricular (LV) pacing thresholdssurrogate
Reducing LV bipolar electrode spacing to 1 or 2 mm may significantly increase PNS thresholds without compromising LV pacing thresholds, potentially reducing PNS complications during cardiac resynchronization therapy.
Main Result
Mean Difference: 5.5
p-value: p=0.003
Abstract
BACKGROUND: Phrenic nerve stimulation (PNS) is a common complication of cardiac resynchronization therapy when left ventricular (LV) pacing occurs via a coronary vein. The purpose of this study was to evaluate the effects of bipolar electrode spacing on PNS and LV pacing thresholds. METHODS AND RESULTS: Electrophysiology catheters with standard (2 mm-5 mm-2 mm) or modified (1 mm-5 mm-1 mm) interelectrode spacing was, respectively, inserted in a posterior/lateral cardiac vein in a randomized order in 6 anesthetized dogs via jugular access. The phrenic nerve was dissected via a left minithoracotomy and repositioned over the vein as close as possible to one of the electrodes. The presence of PNS was verified (ie, PNS threshold 0.05). Compared with a standard bipolar electrode spacing of 20 mm for LV leads, 1 and 2 mm bipolar electrode spacing resulted in a PNS threshold increase of 5.5±2.2 V (P=0.003) and 2.8±1.7 V (P<0.001), respectively. Similarly, PNS threshold increased by 6.5±3.7 V with 1 mm and by 3.8±1.9 V with 2 mm bipolar pacing (both P<0.001), compared with unipolar pacing. CONCLUSIONS: This study suggests that reducing LV bipolar electrode spacing from the standard 20 mm to 1 or 2 mm may significantly increase the PNS threshold without compromising LV pacing thresholds.