Nickel allergy, how deep?

A 41-year-old woman was referred to our Cardiology Unit to evaluate the feasibility of a percutaneous closure of her 20-mm atrial septal defect. During the last few months she had increasing dyspnoea, and an echocardiographic study had disclosed an atrial septal defect with significant right ventricular enlargement. Her past medical history was silent, except for Nickel (Ni(2+)) allergy confirmed by a skin patch test. Ni(2+) allergy is a problematic issue in patients scheduled for Ni(2+)-containing devices. The atrial septal occluder device that we used consists of a metallic alloy composed of 55% nickel and 45% titanium. Starting from the aforementioned case we reviewed all available literature and illustrated our final resolution.