P wave detection and delineation in the ECG based on the phase free stationary wavelet transform and using intracardiac atrial electrograms as reference

Abstract

Robust and exact automatic P wave detection and delineation in the electrocardiogram (ECG) is still an interesting but challenging research topic. The early prognosis of cardiac afflictions such as atrial fibrillation and the response of a patient to a given treatment is believed to improve if the P wave is carefully analyzed during sinus rhythm. Manual annotation of the signals is a tedious and subjective task. Its correctness depends on the experience of the annotator, quality of the signal, and ECG lead. In this work, we present a wavelet-based algorithm to detect and delineate P waves in individual ECG leads. We evaluated a large group of commonly used wavelets and frequency bands (wavelet levels) and introduced a special phase free wavelet transformation. The local extrema of the transformed signals are directly related to the delineating points of the P wave. First, the algorithm was studied using synthetic signals. Then, the optimal parameter configuration was found using intracardiac electrograms and surface ECGs measured simultaneously. The reverse biorthogonal wavelet 3.3 was found to be optimal for this application. In the end, the method was validated using the QT database from PhysioNet. We showed that the algorithm works more accurately and more robustly than other methods presented in literature. The validation study delivered an average delineation error of the P wave onset of -0.32±12.41 ms when compared to manual annotations. In conclusion, the algorithm is suitable for handling varying P wave shapes and low signal-to-noise ratios.

The Physionet QT Database: Study on the Reliability of P-wave Manual Annotations under Noisy Recordings

“…As shown in Figures 1 to 3, the existence of inaccurate annotations of P-waves within the QTDB is undeniable, as previous studies have also reported [12]. In fact, other studies have manually reannotated the QTDB before the application of ECG delineation algorithms [13].…”

Basket-Type Catheters: Diagnostic Pitfalls Caused by Deformation and Limited Coverage

“…Atrial regions were annotated manually (RA: lateral, posterior, septal, roof, and cavotricuspid isthmus area (CTI); LA: anterior, septal, posterior, roof, right pulmonary vein ostium, and left pulmonary vein ostium). QRS complexes were automatically annotated in the surface ECG [14]. An average position was computed for each electrode based on its locations 100 ms prior to the R peaks in the available data segment, in order to minimize the effect of ventricular contraction and respiration on the analysis results.…”

Postextrasystolic T Wave Change to Stratify Risk of Pump Failure Death in Patients with Chronic Heart Failure

“…The T wave was detected using the stationary wavelet transform (SWT) [6]. The detection algorithm starts with the cancellation of the QRS complex (already given in the database) and P wave in the filtered ECG.…”