Figure 10.
The area with slowest conduction at the AVJ did not match the region with largest cushion. A1 and A2: activation time maps of two embryonic hearts at HH stage 20 from the saline and ethanol groups, respectively. The isochrone time interval is 0.01 s. The arrows point to the areas with slowest conduction. Scale bar = 200 μm. B1 and B2: the en face OCT projections of the two hearts overlaid by labeled cushions. The red color is the superior AVJ cushion, whereas the green color labels the inferior AVJ cushion. The yellow color is the overlap between the two cushions. Scale bar = 200 μm. C1 and C2: the en face OCT projections of the two hearts overlaid by the cushion-size curve calculated along the centerline of the heart tube from point P1 to point P2 along the direction of conduction. The arrows indicate the areas with the largest cushion size. D1 and D2: the en face OCT projections of the two hearts overlaid by the cushion thickness curve calculated along the centerline of the heart tube from point P1 to point P2. The arrows indicate the areas with the thickest cushions. E1: the normalized CV and cushion-size curves of the saline heart (same as the heart in A1–D1) calculated from point P1 to point P2. E2: the normalized CV and cushion size curves of the ethanol heart (same as the heart in A2–D2) calculated from point P1 to point P2. F1: the CV and cushion thickness curves of the saline heart calculated from point P1 to point P2. F2: the CV and cushion thickness curves of the ethanol heart calculated from point P1 to point P2. The CV was inverted and all measurements were normalized into the range [0,1] for ready comparison. The black circle represents the slowest conduction. The blue circle represents the largest cushion size in area (E1 and E2) or thickness (F1 and F2). At, atrium; AVJ, atrioventricular junction; CV, conduction velocity; HH, Hamburger–Hamilton; OCT, optical coherence tomography; Vt, ventricle.