Síndrome de twiddler num doente pediátrico

A seven-year-old girl was diagnosed with transposition of the great arteries with ventricular septal defect and pulmonary stenosis. In the neonatal period, a modified Blalock-Taussig shunt was performed, and at the age of six a Rastelli procedure. Postoperatively she required a permanent VVIR pacemaker (Microny II SR, St. Jude Medical, IsoFlex lead) due to irreversible complete AV block. One year after surgery, she was admitted to the Emergency Department due to pectoral stimulation by the pacemaker. Assessment revealed intermittent ventricular stimulation thresholds (variable and above 2.4 V), with unchanged lead impedance. The patient presented advanced AV block. A surgical revision was performed and the pacing lead was extracted by manual traction. There was no macroscopic evidence of lead fracture. A new pacemaker system was inserted (Identity ADx VDR, St. Jude Medical, AV Plus Dx lead), through the right subclavian vein. P and R wave amplitudes were 2 mV and 7.1 mV, respectively, and the ventricular threshold was 0.75 V. The final image showed the pacing lead to be correctly positioned (Figure 1). Five months later, a further revision revealed inadequate atrial sensing (<0.1 mV), with unchanged ventricular