Figure 7.

Effect of pacing site on the development of alternans. (A) APD dispersion amplitude for endocardium (main axis 7 cm) and epicardium (main axis 6 cm) from four different and orthogonal RV pacing sites: apex (P1, blue), posterior free wall (P2, green), base (P3, yellow), and anterior free wall (P4, red) (see Figure S1B in Supplementary Material for stimulus location). Colored bars on the x-axes indicate the points at which each curve has grown by more than 10% compared to its value at the longest CL. (B,C) Alternans maps and activation contour maps at CLs of (B) 150 ms and (C) 80 ms for endocardium and epicardium showing the differences obtained by pacing from the four distinct sites.