Changes in left atrial anatomy due to respiration: impact on three-dimensional image integration during atrial...

Patient respiration influences the accuracy of image integration approaches used during atrial fibrillation (AF) ablation procedures. We assessed both absolute and relative changes in left atrial (LA) and pulmonary venous (PV) anatomy due to respiration and their implications for 3D image integration.

Intensity-based segmentation of the LA and PVs was performed on cardiac computed tomography (CT) images obtained during both inspiration and expiration in 16 patients referred for AF ablation. A 3D LA-PV surface model was reconstructed for each respiratory phase. Absolute and relative respiratory motion components were evaluated from corresponding landmarks in both models. The mean 3D respiratory motion distance for all four PVs was 19 +/- 9 mm. The most important motion component was in the inferior direction, with a mean inferior motion distance of 15 +/- 8 mm. The mean 3D respiratory motion of the PV centers due to relative geometrical changes was small at the ostial level (2.6 +/- 1.4 mm, 95% CI 2.3-3.0 mm) but significantly larger at the level of the first PV bifurcation (4.0 +/- 2.3 mm, 95% CI 3.4-4.6 mm, P < 0.001). Relative geometrical changes of the LA body were most pronounced in regions near the mitral valve, resulting in a changed configuration of the mitral annulus during inspiration.

Respiration causes important movements of the PVs and LA. Relative changes in LA-PV geometry are most pronounced in the distal PVs and in the LA body near the mitral valve. Therefore, these regions should be avoided during registration of pre- and per-procedural images unless they are acquired in the same phase of respiration.