Quantitative assessment of changes in the repolarization phase in Holter recordings using CAVIAR

The authors present a new method for quantitatively assessing the spatiotemporal information content of pseudo-orthogonal Holter recordings. Based on the CAVIAR serial electrocardiogram/vectorcardiogram analysis method, it allows precise measurement of both beat-to-beat morphology and time-interval changes in standard, three-channel analog ambulatory electrocardiogram recordings. All measurements are automatically corrected for delineation errors or changes in the position of the heart. The method has been tested on Holter recordings of head-up tilt tests performed on 22 healthy subjects under controlled breathing: 10 min in supine and 10 min in 90° upright tilt position. Spectral analysis clearly identified spectral events in the QT interval, with very low residual noise, and a significant increase of the QT low-frequency components in the upright tilt position