Form Analysis Using Digital Signal Processing Reliably Discriminates Far‐Field R Waves from P Waves

Abstract

The correct detection of atrial arrhythmias by pacemakers is often limited by the presence of far-field R waves (FFRWs) in the atrial electrogram. Digital signal processing (DSP) of intracardiac signals is assumed to provide improved discrimination between P waves and FFRWs when compared to current methods. For this purpose, 100 bipolar and unipolar intracardiac atrial recordings from 31 patients were collected during pacemaker replacement and used for the off-line application of a novel DSP algorithm. Digital processing of the atrial intracardiac electrogram (IEGM) signals (8 bit, 800 samples/s) included filtering and calculation of the maximum amplitude and slope of the detected events. The form parameter was calculated, being the sum of the most negative value of the amplitude and that of the slope of the detected event. The algorithm collects form parameter data of P waves and FFRWs and composes histograms of these data. A sufficiently large gap between the FFRW and P wave histograms allows discrimination of these two signals based on form parameters. Three independent observers reviewed the reliability of classification with this algorithm. Sensitivity and specificity of FFRW detection were 99.63% and 100%, respectively, and no P waves were falsely classified. It can be concluded that this novel DSP algorithm shows excellent discrimination of FFRWs under off-line conditions and justify the implementation of this algorithm in future pacemakers for real-time discrimination between P waves and FFRWs. This method prevents false mode switching and allows correct and immediate intervention pacing for atrial tachyarrhythmias.

The Effect of Bipole Tip-to-Ring Distance in Atrial Electrodes upon Atrial Tachyarrhythmia Sensing Capability in Modern Dual-Chamber Pacemakers

“…Pre-clinical studies have been very encouraging with a sensitivity and specificity of 99.6% and 100%, respectively, for the discrimination of FFRWO and P waves. 29 Abolishing post-ventricular atrial blanking periods and allowing a higher programmed atrial sensitivity with this technology may also therefore overcome the problem of undersensing. Until this is widely incorporated, atrial electrodes with a TTR of less than 10 mm should be used in devices requiring atrial arrhythmia discrimination.…”

Morphology‐Enhanced Atrial Event Classification Improves Sensing in Pacemakers

“…The algorithm consists of two basic elements: a learning phase and a classification phase. Since morphology and timing of FFRWs differ depending on patients' anatomy, lead characteristics and position, 10,15,17–19 a learning phase is needed in each patient to acquire individual reference FFRW characteristics 13 . In this study, segments 0–3 h, 6–9 h, 12–15 h, and 18–21 h of each 24‐hour Holter recording were used for learning, the remainder for classification.…”

Diagnostic tools for atrial tachyarrhythmias in implantable pacemakers: a review of technical options and pitfalls

“…37,38 Finally, digital processing of incoming signals permits grouping of atrial, ventricular and FFRW events and promotes better discrimination between true P waves, atrial arrhythmias and inadvertent signals. After a short learning period, these PM algorithms can adapt continuously to new wave forms and discriminate between various types of atrial tachyarrhythmias.…”

“…After a short learning period, these PM algorithms can adapt continuously to new wave forms and discriminate between various types of atrial tachyarrhythmias. 37,38 Verifying automated detection of atrial tachycardia For the diagnosis of atrial signals, the PM utilises the electrogram (EMG) transmitted by the atrial lead. Atrial signals are modified by the atrial amplifier (see above).…”