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Letter to the Editor

1. It is unclear whether they used a screw-in lead at the time of the first implantation (Figs. 1 and 2 seem to show a passives fixation lead). As some fibrous attachment of the lead to the vein may be anticipated, lead tip fixation is important for the traction related to growth to exert its net effects in a way that favors sliding of the body of the lead and retraction of the loop. In addition, it is likely that less of a fibrous reaction around the lead loop has occurred in our cases due to a larger diameter of the inferior vena cava at our patients’ older age. 2. Even though lead insulation material is the same in defibrillator and pacemaker leads, lead flexibility differs substantially. In all likelihood, the stiffer the distal end of a lead (provided its tip is firmly anchored), the stronger the traction that can be exerted on the proximal portion of the lead. Such a mechanism could further explain release of the loop seen in our cases as opposed to Antretter’s case. 3. The solution we have suggested was specifically addressed to defibrillator leads implantation. Pacemaker leads may behave quite dif-