Morphologic identification of ectopic P-waves from surface ECGs can be challenging, particularly when the P-wave is buried in the QRST wave complex. Because ECGs are often available on paper and not digitally, we developed a method of subtracting the T-wave from the buried P-wave complex on paper ECGs.To validate our system, an atrial extrastimulus was introduced during and following the T-wave. The ECGs were scanned and then transformed from an image format to a digital format. A computer algorithm digitally subtracted a QRST with no buried P-wave from one with a buried P-wave, thus resulting in an extracted P-wave. The extracted P-waves were compared to the nonburied P-wave by determining correlation coefficients and by visual grading by two independent reviewers.Visual grading comparing the buried P-wave with the exposed paced P-wave was 94%. The median correlation coefficient was 85%.An ectopic atrial P-wave obscured by a coincident QRST wave complex can be accurately derived from printed ECG using this PC-based system. Addition of this technique to the existing methods may aid in the localization and ablation of ectopic atrial foci.
View details for Web of Science ID 000228826100004
View details for PubMedID 15842425