Evaluation of Philips Diagnostic ECG Interval Measurements
JM Lindauer, RE Gregg
Philips Medical Systems
Milpitas, CA, USA
To evaluate a novel method for detecting onsets and offsets of ECG wavelets, the Philips 12-Lead Algorithm was run on the CSE measurements database (12 lead, original series, 125 records). P-onset, P-offset and T-end were detected by creating a slope line from the relevant wave peak to the waveform beyond the expected inflection point. The actual inflection point was taken as the maximum absolute difference between the slope line and the actual waveform at each time point. This method avoids use of estimated isoelectric line and requires no thresholds. Noise reduction is accomplished by measurement on averaged representative beats.
Measurement Suggested Limits Philips - Reference
Mean Std Dev Mean Std Dev
P duration ± 10 15 0.1 6.8
PQ interval ± 10 10 2.3 5.7
QRS duration ± 10 10 -4.6 4.4
QT interval ± 25 30 1.6 8.7
The results show generally excellent agreement with small standard deviation. This suggests robustness of the technique, but further studies are required to fully evaluate the repeatability and applicability to normal values.