Fatal contrast medium-induced adverse response to iohexol in carotid artery angioplasty A case report

Rationale: Adverse drug reactions (ADRs) to iohexol occur infrequently and generally result in good outcomes. This report describes a 51-year-old man suffering from an ADR to iohexol (Omnipaque 300), which proved fatal. Patient concerns: The patient was admitted to hospital due to intermittent dizziness over 2 years and transient numbness and weakness of the right limbs for 1 week. The patient was investigated using carotid artery angioplasty (CAA), during which the patient suffered a sudden disorder of consciousness and a tonic-clonic seizure leading to status epilepticus. After the CAA, the patient suffered from increasing cerebral edema volume. Diagnoses: Results of digital subtraction angiography and computed tomography angiography performed at another hospital before the CAA suggested severe stenosis of the left internal carotid artery at the spinal C1 level. In the processes of intraoperative and postoperative CAA, the patient developed severe allergic reactions to the contrast agent including epilepsy, brain tissue edema, and renal failure, which were typical according to the 10th edition of the American College of Radiology Manual on Contrast Media (ACR Manual on Contrast Media, Version 10.3, 2017). Interventions: The patient was treated with antiepileptic, antianaphylactic therapy, and control of blood pressure. Due to rapid and severe brain edema, a decompressive craniectomy was performed on the left side, but it was unsuccessful in reducing brain edema. Subsequently, the patient was started on continuous renal replacement therapy for progressive renal dysfunction. Outcomes: Despite the use of a variety of medical and surgical interventions, it was not possible to control the patient's condition, which gradually declined leading to death, 7 days post-CAA. Lessons: To the authors' knowledge, this represents the 1st case of fatal contrast-induced ADR to iohexol during CAA. Although a variety of preoperative tests for iohexol allergy were performed according to recommendations from the ACR Manual on Contrast Media (Version 10.3, 2017), severe complications related to iodized contrast agent still occurred. If the ADR had been recognized sooner and decompressive craniectomy and continuous renal replacement therapy were applied earlier, it would have improved the patients' prognosis.