Incidence and Characteristics of Far-Field R-Wave Sensing in Low Right Atrial Septum Pacing

Abstract

Circulation Journal Official Journal of the Japanese Circulation Society http://www. j-circ.or.jp acemaker diagnostics have become an important means of detecting and monitoring atrial tachyarrhythmias (ATA) in recipients of pacemakers implanted for bradyarrhythmias. State-of-the-art dual-chamber devices provide useful diagnostic information, including the number and duration of automatic mode switch episodes upon detection of ATA. In the recent ASSERT trial, with over 2.8 years of follow-up, (1) ATA were detected by the atrial high rate episode function in 36% of 2,580 pacemaker or implantable defibrillator recipients who had no history of ATA before device implantation, and (2) a 2.5-fold higher incidence of ischemic stroke or systemic embolism was observed in patients with than in patients without ATA detected by the atrial high rate function. 1,2 Therefore, accurate identification of ATA allows the planning of optimal antiarrhythmic and antithrombotic therapy. 3 However, the sensing of the far-field R-wave (FFRW) by the atrial channel may cause inappropriate mode switches from DDD to DDI mode, and trigger ATA or cause pacemaker syndrome. 4-14 Editorial p 582The right atrial appendage (RAA) is believed to be an unsuitable pacing site for the prevention of ATA, because it lengthens the inter-or intraatrial conduction time and increases the dispersion of atrial refractoriness. 15 Therefore, low atrial septal (LAS) pacing has been recommended instead of RAA pacing to prevent ATA, 16 though this remains to be confirmed by randomized clinical trial. 17 However, because the LAS region is closer to the ventricle than the RAA, it may be associated with a higher likelihood of FFRW oversensing, 16,18 though the prevalence and characteristics of FFRW sensing associated with LAS pacing have not been formally studied.We hypothesized that recipients of bipolar atrial leads with widely spaced tip-ring electrodes implanted in the LAS and who have left ventricular hypertrophy (LVH) on 12-lead ECG are at increased risk of FFRW sensing after ventricular pacing. To test this hypothesis, we measured the prevalence and examined the characteristics of FFRW sensing in recipients of dualchamber pacemakers, as well as the effects of the tip-ring Toshihisa Nagatomo, MD; Yutaka Otsuji, MD Background: Although low atrial septal (LAS) pacing may prevent atrial tachyarrhythmias in selected patients, farfield R-wave (FFRW) sensing in this region seems more likely than in the right atrial appendage.

Use of an Atrial Lead with Very Short Tip-To-Ring Spacing Avoids Oversensing of Far-Field R-Wave

“…Therefore, we cannot comment on the lead performances and potential detection of far-field R-wave signals at other sites such as the lower atrial septum for which a higher risk of FFS has been described [21], [22] or for the Bachmann bundle region for which low amplitudes of far-field R-wave signals have been reported [23].…”

Pacing From the Right Ventricular Septum and Development of New Atrial Fibrillation in Paced Patients With Atrioventricular Block and Preserved Left Ventricular Function

“…If far-field R wave oversensing was confirmed by iEGM, the post-ventricular atrial blanking was set at a longer or equal duration than the far-field R wave oversensing +25 ms to prevent double atrial counting. 16 At 3 months after device implantation and at every 6-month interval thereafter, a 12-lead ECG and chest X-ray were obtained, and we reviewed the patient's medication list and health status, including the interim development of palpitation or chest pain. At each visit, we recorded the cumulative percentage of atrial (cumul%AP) and ventricular (cumul%VP) paced events, the atrial and ventricular pacing and sensing thresholds, and the measurements of lead impedance.…”

“…15, 16 Patients in whom AF was confirmed at the 3-month visit were removed from the study to exclude patients with AF unrelated to RV pacing.…”

Troubleshooting Implantable Cardioverter-Defibrillator Sensing Problems II

“…Thus, there is a correlation between far-field R-wave oversensing and left ventricular hypertrophy. 7 The second is interelectrode spacing. 8 Closely spaced electrodes (1.1 mm) minimize far-field R waves in comparison with conventional 10-mm spacing, but they also reduce the amplitude of atrial electrograms during short-term follow-up 9,10 and may not record adequate atrial electrograms in diseased atria.…”

“…7 High Septal Right Atrium Leads placed at the junction of the superior vena cava and septal right atrium (adjacent to the noncoronary cusp of the aortic valve) are in close proximity to the left ventricular outflow tract. In contrast to these locations, leads placed in the lateral right atrium 11 or Bachman bundle region 12 minimize far-field R-wave oversensing.…”