Abstract 1998: Noninvasive Evaluation of Tissue Characteristics of Left Atrium with Atrial Fibrillation by Using Three Dimensional Integrated Backscatter Transesophageal Echography (IB-TEE)
Background: It is recognized that one of the causes of atrial fibrillation (AF) is pathological degeneration of the left atrium (LA). However, there has not been an appropriate noninvasive method to evaluate degeneration of the LA in the clinical setting.
Methods: Integrated backscatter (IB) images were acquired with transesopageal echography (TEE) (Sonos 7500) using a 4 to 7 MHz transducer for all studies. IB values were calculated as the average power of the backscattered signal from regions of interest (ROI). In a pathological study, we measured IB values of 15 left atrial specimens obtained from 10 autopsied hearts. Tissue was stained with hematoxylin and eosin and Masson’s trichrome. Percentages of interstitial area in ROI were automatically calculated by a personal computer. In the clinical study, we measured IB values of entire free wall of the LA at every 5mm in 24 patients (16 AF patients and 8 non-AF patients). Each IB value was corrected by subtracting the IB values of the cardiac chamber and color-corded to construct three dimensional images.
Result: There was a significant correlation between the percentages of interstitial area and IB values (r=0.45, p=0.038). As the degeneration of the LA increased, IB values also increased. IB values of the LA were significantly higher in the patients with than without AF (16.9 ± 4.5 versus 29.3 ± 4.2, p=0.003). 3D IB-TEE color-coded maps of the LA showed the location of degenerated area well.
Conclusion: By using IB-TEE, we can easily identify an increase in interstitial fibrosis in the LA in patients with AF. This is the first demonstration of the degeneration of the LA using IB-TEE for non-invasive evaluation.