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When putting in a left ventricular assist device (LVAD), implantable cardioverter defibrillator (ICD) leads are likely to malfunction during left ventricular (LV) unloading, although often just temporarily, according to a small single-center study.

ICD right ventricle (RV) sensing was less than half baseline for 22% of patients following LVAD implantation, while 28.1% exhibited a high voltage impedance change greater than 10 ohms.

These changes were first detected soon after , , of Pauley Heart Center in Richmond, Va., and colleagues reported in JACC: Clinical Electrophysiology.

Compared with patients with no decreased sensing, RV lead sensing was more likely to be halved after ICD implant in patients with:

• An older ICD implant (87.8 versus 30.4 months)
• Lower GFR (48.7 versus 68.4, P=0.0489)
• Concomitant RV assist device placement (42.9% versus 0%, P=0.0071)
• Concomitant tricuspid valve surgery (57.1% versus 16%, P=0.0469)
• Cardiac tamponade or other unplanned return to the operating room (57.1% versus 12%, P=0.0258)

Over time, improvement was recorded for 30% of leads with decreased RV sensing, 50% with elevated RV threshold, and 33% with increased pacing threshold.

"ICD lead malfunction can occur following LVAD implantation, but may improve over time. Intraoperative RV sensing and high voltage impedance changes were not detected until after weaning of cardiopulmonary bypass, suggesting the mechanism of RV lead malfunction may be related to LV unloading and concomitant leftward septal shift," they concluded.

"Decreased RV lead sensing is concerning because it may lead to underdetection of tachyarrhythmias and delay of appropriate therapy," they wrote. And contrary to prior hypotheses, they noted that "mechanical disruption of the leads during surgery did not explain our findings."

Kron and colleagues concluded that "the return of some parameters to baseline over the weeks and months following ventricular assist device highlights the need for careful monitoring and cautious decision-making prior to lead interventions."

"Such improvements over time may be due to geometry changes and further left ventricular remodeling," the authors suggested. "However, pharmacologic, metabolic, and endocrine changes that are rapidly occurring during the post-operative period may also play a role."

The investigation included 32 patients with ICDs who underwent LVAD implantation between 2011 and 2014.

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