Investigation on the optimal implantation site and setting of Reveal LINQ ® avoiding interference with performance of transthoracic echocardiography.

Background: The optimal implantation site of a new implantable cardiac monitor (ICM) named Reveal LINQ® may be limited based on a sufficient amplitude of R wave potential (AEP) acquisition because it is the same anatomic area used for transthoracic echocardiography (TTE).

Methods: Among 18 healthy volunteers, we assessed AEPs in 3 combinations through parasternal placement of 2 electrodes, (i) in the 4th intercostal space (ICS; site A/setting a; A/a), (ii) the same setting in the 5th ICS (site B/setting a; B/a), and (iii) in a sagittal plane relative to the left sternal border at the 4th ICS (site A/setting b; A/b), and further measured AFPs in several body positions in all site-setting combinations: supine, left and right lateral decubitus, sitting, and standing. The degree of interference with TTE performance was assessed by placement of an imitation ICM in setting a at both sites A and B.

Results: Only the AEPs in A/a and B/a met the criteria (AEP ≥ 0.3 mV) in all positions. The AEPs in the supine position with all combinations were higher than those achieved in other positions ( P < .001). The imitation interfered with TTE performance at site A among 78% of subjects, but only 17% at site B ( P = .0006). The end-diastolic dimension of the left ventricle at site A was decreased after the imitation placement ( P = .028). At site B, all female subjects complained of discomfort because their brassieres overlaid the imitation.

Conclusion: The B/a combination is optimal; however, the personal discomfort related to brassieres should be considered.