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INTRODUCTION:
Nitinol allergy is a rare phenomenon, with few reported cases in the literature. However, allergy to nickel, a predominant component of nitinol, is much more common. Despite the prevalence of nickel allergy few patients present with clinical manifestations.
METHODS:
This is a case report.
RESULTS:
A 57-year old male presented reporting a history of right lower extremity claudication treated four-months prior at an outside facility by placement of three self-expanding nitinol stents in the superficial femoral artery (SFA). In the week following the procedure, the patient began to notice small “hives” over many parts of his body. He was evaluated by dermatology and then subsequently an allergist for testing and was found to have a severe nickel allergy. The patient had no past medical history of metal allergy or other allergic reactions. The stent manufacturer provided a sample nitinol stent for further testing, to which the patient also presented a macular erythematous reaction. The patient was determined to have a significant reaction to the nitinol stents and desired their removal if possible.
The patient was taken to the operating room for above-knee femoral popliteal artery bypass with polytetrafluoroethylene (PTFE) graft, explantation of three stents in the SFA. The patient’s common femoral artery (CFA) was first localized and proximal and distal control was obtained. We then identified the proximal extent of the SFA stents. Above knee medial popliteal exposure was obtained and a subcutaneous tunnel formed. An 8-mm PTFE graft was used to bypass the SFA, from CFA to popliteal artery. The SFA was ligated with non-absorbable suture, proximal to the SFA stents and distal to the last stent.
The CFA dissection was continued onto the SFA and arteriotomies were made sequentially down the SFA removing the stents whole. Post-removal plain radiographs were taken to ensure complete device removal. His allergic symptoms had resolved by his postoperative visit on postoperative day 10. At his two month follow-up visit his bypass was patent and the patient had no recurrence of his symptoms.
CONCLUSIONS:
Nickel allergy is a common phenomenon with nearly 16.2% of people in North America having some level of reaction. Despite this prevalence, the incidence of adverse reactions to medical devices containing nickel is relatively rare. We present a case report of nickel allergy confirmed via skin patch testing to nickel as well as to the nitinol stent itself, as well as a management strategy. Case reports of reactions to nickel containing devices are disparate, and the clinical presentations varied. Preoperative testing may be a useful adjunct in patients with a positive history. Treatment for allergy may be medical immunosuppression therapy or surgical device explantation dependent on the patient’s symptoms, the device, and their perioperative risk of surgery.