Figure 1. (A) Baseline ECG of the patient showing sinus rhythm with first degree AV block, right bundle branch block and right axis (25 mm/sec). Tall morphology of the patient may explain the right inferior QRS axis, although left posterior fascicular block can not be ruled out (even if unlikely due to the normal HV interval and lack of surgical injury on the inferior ventricular septum). Right bundle branch block may be the consequence of the surgery of the supravalvular pulmonary artery stenosis as realized at one year of life or of the right ventricular overload because of the pulmonary artery stenosis. Alternatively intraventricular conductions disturbances have also been described following surgical closure of atrial septal defect (see text for explanations). (B) Baseline ECG strip (VR, VL, VF leads) revealing spontaneous type 1 second degree AV block (25 mm/sec)
