Inappropriate shock delivery is a major problem in patients with an implantable cardioverter-defibrillator (ICD). At least one inappropriate discharge is experienced by up to 21% of such cases during 1 to 5 years of follow-up [1]. Shock delivery causes pain, anxiety and depression in ICD recipients, compromising their quality of life [2], and may lead to death, due to the triggering of a true ventricular fibrillation [3]. The occurrence of inappropriate shocks doubles the risk for death in patients with heart failure who received an ICD for primary prevention [4] .T he main mechanisms of this complication are misclassification of supraventricular tachyarrhythmias, or oversensing of both cardiac and non-cardiac signals [5]. Non-cardiac signals, named noise, are originated from the external environment or stemming from lead insulation defects or fractures and account for up to 4% of delivered shocks [5]. We report a 71 year old woman with ischemic heart disease, left ventricular ejection fraction of 0.42, repetitive syncope, non-sustained ventricular tachycardia (VT)at24-hour Holter monitoring, and a hemodynamically unstable monomorphic VT, requiring electrical external cardioversion, induced by programmed ventricular stimulation at electrophysiological study. A double-chamber ICD (Belos DR, Biotronik, Germany) with a true bipolar lead ventricular electrode (Kentrox RV, Biotronik, Germany) was implanted. For ventricular tachyarrhythmias, 3 zones were programmed: VT1 (N370 ms/b162 beats per minute [bpm]), ECG monitoring; VT2 (320 to 370 ms/162 to 188 bpm), 3 bursts plus premature extra stimulus followed by 8 shocks of 30 J; and VF (b320 ms/N188 bpm), 8 shocks of 30 J. Standard bradycardia pacing parameters were obtained. Four months after ICD implantation, the patient was admitted in the coronary care unit with a haemorrhagic stroke, presenting respiratory insufficiency, requiring intubation after adequate sedation. Right internal jugular vein was obtained for fluid and drug infusion. With the introduction of the metallic guide, the operator realised that the ICD had carried through some discharges, without arrhythmic disorders evidenced by the ECG monitor. Then, the guide metallic, along with the introducer sheath, was withdrawn, and it was carried through a new access, with