Figure 2. On the left side: surface electrocardiogram (ECG) and intracardiac electrograms (EGM) recording the earliest activated signal of the right ventricle during right atrium pacing in a patient with pre-excitation. On the right, 3D reconstructions of the tricuspid valve and right ventricle with activation map during atrial pacing. The reduced activation window shows a gradient of colours from red (earliest activated site) to purple (latest activated site). The red dot shows the successful ablation site, 9 mm distant from the site where we produced mechanical AV block with high contact force > 20 grams (Blue dot). The yellow dots show the site where the His potential was recorded.