This ECG is from a patient with history of repaired tetralogy of Fallot.

This ECG shows sinus rhythm and right bundle branch block morphology (RBBB) with the rate of 75 bpm and secondary ST-T wave changes in V1-3. V1 shows rsR' pattern and V6 shows RS pattern( S is wider than R wave, and S>40 msec in duration) which are consistent with RBBB. RBBB after repair of tetralogy of Fallot is often unavoidable and usually produced by infundibular resection. Prolonged QRS duration also has negative prognostic role in TOF patients.