番茄社区

SAN DIEGO -- Removal of atrial septal closure devices cleared up persistent symptoms of nickel allergy in a series of 10 consecutive patients reported here.

All had systemic symptoms for at least a year despite conservative medical therapy, which then resolved after minimally invasive removal of the implanted closure device, Div Verma, MD, of the University of Utah in Salt Lake City, and colleagues reported at the Society for Cardiovascular Angiography and Interventions meeting.

All ten also had a history of metal allergy, a positive patch or skin prick test for nickel allergy before implant, or both.

"In patients undergoing percutaneous ASD [atrial septal defect] or PFO [patent foramen ovale] closure, particularly those with a history of metal allergy, routine nickel allergy testing should be considered to identify patients at higher risk of an exaggerated inflammatory reaction in whom surgical closure may be favored," Verma told attendees.

Prick testing is probably more helpful than patch testing for contact dermatitis, he suggested.

Positive skin prick test for nickel was more strongly associated than patch testing was with early onset of symptoms within 2 weeks of implant (100% versus 67%) and recurrent migraine or transient ischemic attack (100% versus 25%).

A fraction of patients who get contact dermatitis from nickel will end up reacting to the nickel in cardiac devices, he acknowledged. All available closure devices release some level of nickel, although it varies by device, his group had previously shown.

"The biomedical device undergoes corrosion, releasing nickel particles which act as haptens and trigger the immune response," he said.

One member of the audience challenged that conclusion without knowing the denominator on how many skin-test positive patients had been fine with their implant.

"I don't know what I'm going to do with the result" from a positive test, he said. "My understanding is that the incidence of hypersensitivity to nickel in the general population is about 10%."

"At our center, if somebody has a prick test positive, we strongly counsel them for a surgical closure as opposed to a device closure," Verma said.

But he agreed that the small observational study could only be considered hypothesis generating.

Others questioned how many patients had been explanted.

"Over the last 10 to 15 years, there have been maybe two cases of severe nickel allergy," one member of the audience noted, and only one had to have her device taken out at his institution.

His relatively large case series of explants in such patients -- independently evaluated by a cardiologist, dermatologist, and cardiothoracic surgeon -- may have been because of his state's history of ASD and PFO closure. "Our denominator was large."

Symptoms of systemic nickel allergy usually don't include rash, but often present as a combination of chest pain, breathlessness on exertion, and mild leukocytosis and can include migraine and pericarditis as well.

The three patients tested for nickel in their urine at an average of 40 months after implantation showed elevated levels that then normalized after removal of the device.

Techniques used for explant were minimal right thoracotomy with patch repair of residual atrial septal defect in five and primary closure for the other five. No surgical complications occurred.

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