561 The Effect of Device Orientation on R-Wave Amplitudes in the ConfirmRx Cardiac Monitor

Abstract

Optimal functioning of arrhythmia detection algorithms in insertable cardiac monitors depends on consistent R-wave sensing. To identify the ConfirmRxTM device insertion orientation that maximises R-wave amplitude. Patients clinically indicated to receive a ConfirmRxTM device underwent R-wave amplitude assessment in various postures (supine, lying on right side [RS], lying on left side [LS], sitting, and standing) immediately post-insertion and 30 days post implant. The device was inserted at the 4th intercostal space in one of two orientations: 1) parasternal [PS] or 2) 450 to the sternum [450S]. Seventy-four patients were included in the study with the device inserted 450S in 43 patients and PS in 31 patients. R-wave amplitude in the 450S orientation was consistently higher than the PS orientation in most postures both immediately post-insertion (supine: 0.67±0.05 vs 0.52±0.05 mV, RS: 0.51±0.05 vs 0.38±0.04 mV) and after 30 days (supine: 0.68±0.06 vs 0.49±0.04 mV, RS: 0.63±0.06 vs 0.43±0.04 mV, LS: 0.57±0.06 vs 0.41±0.04 mV, standing: 0.60±0.05 vs 0.45±0.04 mV). Post-insertion R-wave amplitude in the 450S orientation was lower in the RS, LS and sitting postures than supine; p<0.05. In the PS orientation, post-insertion R-wave amplitude was significantly lower than supine only in the RS posture (p<0.05). At 30 days post-implant there was no longer any significant difference between any of the postures. This study identifies 450 to the sternum as the insertion orientation that maximises R-wave amplitude immediately post-insertion and 30 days post implant enabling accurate event detections.Figure 2View Large Image Figure ViewerDownload Hi-res image Download (PPT)