Fig. 8.

Identification of the block zone with OCT. (a) Photograph of an SA nodal preparation as viewed from the endocardium with the OCT field of view for the SA nodal block zone identified by the white box. OCT images of the fiber orientation are shown at (b) 0.07 mm, (c) 0.12 mm, (d) 0.18 mm, (e) 0.24 mm, (f) 0.32 mm, and (g) 0.42 mm below the endocardium. The white arrow in (c) indicates the probable anatomic correlate of the functional block zone. The dotted white lines indicate the pathways for impulse propagation around the block zone. The red arrow indicates fibers that “dead-end” in the functional block zone. Abbreviations: SVC, superior vena cava; IVC, inferior vena cava; RAA, right atrial appendage; IAS, interatrial septum. (Video 2, MOV, 5.9 MB) [URL: http://dx.doi.org/10.1117/1.JBO.17.7.071309.2]