Atrial lead location at the Bachmann's bundle region results in a low incidence of far field R-wave sensing

Abstract

The aim of the study was to investigate far field R-wave sensing (FFRS) rate and characteristics at different right atrial (RA) positions in patients treated with multisite atrial pacing, with the RA lead implanted at the Bachmann's bundle (BB) area in 69 patients, in comparison to RA appendage (RAA) in 70 patients. All measurements were done during sinus rhythm in supine patients, with unipolar (UP) and bipolar (BP) sensing configuration. The presence, amplitude threshold (FFRS trsh) and FFRS timing were determined. Sensing safety margin was defined as the ratio of sensed P-wave vs. FFRS trsh, for both the minimal (Pmin) and the mean (Pmean) P-wave amplitude. At both atrial locations BP sensing was superior to UP in FFRS rejection (P < 0.0001). At 0.5 mV sensitivity level (BP) FFRS occurred in 1% of patients at the BB site vs. 11% at the RAA (P = 0.01). FFRS trsh (BP) was 0.2 +/- 0.1 mV at the BB vs. 0.4 +/- 0.3 mV in the RAA position (P < 0.0001). Sensing safety margin, when determined for the Pmin amplitude was > or =5 in 99% of patients from the BB group, in comparison to 66% of RAA patients (P < 0.0001), in whom it was <2 in 13%. Even with the use of BP leads equipped with a 10 mm tip-to-ring spacing FFRS incidence was lower at the BB site (P < 0.01), FFRS trsh was lower (P < 0.001), and sensing safety margin was higher vs. RAA (P = 0.002). Bachmann's bundle area features optimal conditions for signal sensing, and such atrial lead positioning may offer advantages to prevent oversensing of R-wave, thus improving functioning of standard dual chamber pacemakers, ICDs and CRT-Ds.