Key result
Short-spaced bipolar pacing successfully avoided phrenic nerve stimulation up to 9V pacing, whereas standard bipolar pacing induced it at 5.0V.
Why the study?
Does short-spaced bipolar pacing prevent phrenic nerve stimulation in a patient undergoing CRT-D implantation with limited venous branches?
Case Report (n=1)
No
Does short-spaced bipolar pacing prevent phrenic nerve stimulation in a patient undergoing CRT-D implantation with limited venous branches?
Short-spaced bipolar pacing using a quadripolar lead may be a beneficial strategy to avoid phrenic nerve stimulation during CRT implantation when available venous branches are limited and close to the phrenic nerve.
May facilitate CRT in limited CS anatomy despite PNS; leaves open optimal vector selection for routine use.
A 48-year-old woman underwent cardiac resynchronization therapy defibrillator implantation. Coronary sinus (CS) venography showed only one adequate anterior branch for a left ventricular lead. We were able to introduce a quadripolar left ventricular lead (Medtronic 4398-88 cm) to the distal portion of the anterior branch. Although phrenic nerve stimulation (PNS) occurred due to distal bipolar pacing (distal 1-mid 2, with 21-mm distance) and proximal pacing (mid 3-proximal 4, distance 21mm), short-spaced bipolar pacing (mid 2-3, distance 1.3 mm) did not induce PNS until 9V pacing. Shared bipolar pacing from each left ventricular electrode (distal 1 to proximal 4) as cathode and a right ventricular (RV) coil as anode resulted in PNS by 3.0V at 0.4 ms. Although quadripolar pacing could avoid PNS by switching the pacing site (ie, from distal bipolar to proximal bipolar), it might not avoid PNS in cases where the phrenic nerve and CS branch are parallel and in close proximity. We found that even though the phrenic nerve and CS branch were parallel and close, short-spaced bipolar pacing could avoid PNS. In conclusion, short-spaced bipolar pacing selected by quadripolar pacing might be beneficial to avoid PNS when the implantable branch is limited.
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Kabutoya et al. (2016) conducted a case report in Heart failure with cardiac dyssynchrony requiring CRT-D (n=1). Short-spaced bipolar pacing using a quadripolar left ventricular lead vs. Standard distal or proximal bipolar pacing was evaluated on Occurrence of phrenic nerve stimulation (PNS). Short-spaced bipolar pacing successfully avoided phrenic nerve stimulation up to 9V pacing, whereas standard bipolar pacing induced it at 5.0V.
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