Figure 2.

Epicardial Recovery Time (RT) Maps. A. Maps are shown in superior (top row) and inferior (bottom row) views for control, LQT1 (patient 15), LQT2 (patient 16), and LQT3 (patient 8). All three LQTS subjects had regions with abnormally long RT as shown by predominant magenta and white colors in the maps. The maximum RT value in LQTS was 470 ms. The maximum RT value in the normal heart (left most column) was 360 ms (predominant blue and green colors in the map). The heterogeneity in ventricular recovery resulted in large RT differences in all three LQTS types. The solid yellow line (top panels) connects two closest neighboring EGMs (from site 1 and site 2) with maximum ΔRT. In all three LQTS patients, ΔRT (RT(1)-RT(2)) exceeded 100 ms (compared to normal value of only 28 ms in the left most column). As a result, there was a steep gradient of repolarization ΔRT/Δx across this region (shown by black arrows); it was much steeper than control (Normal: 6 ms/cm, LQT1: 102 ms/cm, LQT2: 159 ms/cm, LQT3: 139 ms/cm). B. ECGI-reconstructed unipolar EGMs from the three LQT patients exhibited drastic changes in T-wave morphology across the yellow line. The T waves obtained from site 1 (red) were inverted or predominantly negative compared to those from site 2 (blue; upright or predominantly positive). Such T-wave changes over a short distance (<10 mm) were absent in the control group. RT (time of dV/dt max during upstroke of T wave) is indicated by the pink dot on the corresponding EGMs (site 1 red; site 2 blue). Corresponding 12-lead ECG tracings are provided in Supplemental Figure 1. mV = millivolts.