Quantification of immunofluorescence (IF) intensity and distribution along the lateral surface and at ICD of ventricular myocytes immunostained for Na _V 1.5, EB1, β-Tub, and nCadherin (nCad). Top: Representative Airyscan images. The central z-plane image with a clearly defined cellular contour was used for quantification. Pixel contents = background-subtracted mean pixel value times cellular area. Bottom left: IF signal within an area 1 μm from cellular contour normalized by total pixel content gave “% pixel contents on the lateral surface.” This value was divided by % cellular area within the 1 μm rim and defined as “degree of enrichment on lateral surface.” Bottom right: IF signals within all areas demarcated by nCad IF signals were summed and normalized by total pixel content to give “% pixel contents at ICD.” This value was divided by “% cellular area demarcated by nCad signals,” and defined as “degree of enrichment at ICD.”