Simulated ECGs in the structurally abnormal heart during reduction of sodium conductance (A) or of the simulated size of the gaps in the introduced barriers by reduction of the coupling in the gaps (B) and corresponding graphs relating excited elements with ST-segment elevation in the right precordial leads. Reduction of the sodium channel conductance below 50% of normal resulted in a rapid reduction excited elements and in ST-segment elevation on the ECG. A reduction in the size of the gaps in the barriers at normal sodium conductance also resulted in a reduction in the excited elements and in ST-segment elevation on the ECG. However, the increased resistance between the excited and unexcited elements limited the ST-segment amplitude.