Fig. 2.

a Posteroanterior and b lateral radiographs demonstrating transvenous pacing system in an 18 kg child with long QT (LQT) syndrome. Generator has been placed abdominally with lead tunnelled to left subclavian vein (cross). Note redundant loop to accommodate growth (star). c Posteroanterior and d lateral radiographs demonstrating a more complex hybrid system in a 15 kg child with LQT type 3. The first ICD implanted was non-transvenous, with intrapericardial coil (asterisk) and epicardial sense and pacing leads (white arrows). Subsequent failure of the epicardial pacing leads with R‑wave undersensing and rising defibrillation threshold necessitated upgrade of the system with subcutanous coil (scc) and transvenous atrial (a) and ventricular (v) pace and sense leads (c and d courtesy of Jasveer Mangat, Great Ormond Street Hospital, London)