Session P91.1

Wavelet Variance Differences in Atrial Fibrillation during Anaesthetic Effect

R Cervigón, F Castells*, J Moreno, J Mateo,
C Sánchez, J Millet

Universidad de Castilla-La Mancha
Cuenca, Spain

Effect of anaesthetic agents in restoration rhythm procedures during atrial fibrillation (AF) has not been fully investigated. We evaluated the effects of a widely used anaesthetic agent (propofol) in the fibrillation patterns. Intra-atrial recordings belong to 18 patients diagnosed with AF were analyzed “before” (baseline) and “during” anaesthetic infusion.
The goal of this study is to characterize the variation in atrial properties along the atria in both states. The wavelet variance decomposes the variance of a time series on a scale by scale basis and hence has considerable appeal when physical phenomena are analyzed in terms of variations operating over a range of different scales. The variance estimates are more accurately determined with a maximal-overlap version of the wavelet transform. Both the Mallat orthogonal-pyramid algorithm for determining the discrete wavelet transform (DWT) and a pyramid algorithm for determining the maximal-overlap version of the transform are presented in terms of finite vectors (MODWT). As mother wavelet was used the haar wavelet and DWT partitioned the variance of the signals over 7 scales. Wavelet analysis highlights a significant lower changes during the anaesthetic infusion respect to the basal conditions in the right atrium (RA), with an opposite effect and non significant values in the left atrium (LA), (ANOVA coupled with the Student-Newman-Keuls test), ( RA (7.53± 5.73 (basal) vs. 3.92± 2.90 (propofol) p= 0.01 and LA (4.94± 3.79 (basal) vs. 6.78± 5.54 (propofol) p= 0.37).
The proposed methodology provide an additional approach to the understanding of the role of the anaesthetic, showing a decrease in the variance inter-scales during the anaesthetic infusion in the right atrium, with the opposite effect in the left atrium (i.e. a increase in the organization degree). The influence of propofol in the electrical activity of the atria was more noticeable in patients with paroxysmal AF than in patients with persistent AF, where the degree of variation was lower.

(Abstract Control Number: 96)