[A case of heparin-induced thrombocytopenia (HIT) developing into seizure and respiratory arrest caused by continuous intravenous heparin infusion for multiple cerebral infarcts].

A 67-year-old man who was on medication for hypertension and unstable angina pectoris developed mild left hemiparesis on day X-1. He made an emergency call at 4 am on day X due to persistent symptoms. Brain magnetic resonance imaging performing following admission showed multiple acute cerebral infarcts, resulting in the initiation of treatment by continuous intravenous heparin was started. One hour later, after initial heparinization, he developed generalized seizure and stopped breathing on echocardiography. Emergency tracheal intubation was performed, and contrast-enhanced brain computed tomography showed hypoperfusion of the right middle cerebral artery; consequently, we performed mechanical thrombectomy. During emergency thrombectomy, multiple new thrombi were observed on cerebral angiography. We suspected heparin-induced thrombosis (HIT), and therefore changed heparin treatment to argatroban, following which the thrombi disappeared immediately. The diagnosis of HIT was comfirmed by complete blood count and serological examination, which revealed thrombocytopenia and anti-HIT antibodies, respectively. As was observed in our patient, spontaneous HIT without recent exposure to heparin can occur in rare circumstances; as such, heparin treatment should be administered with caution. As mechanical thrombectomy is usually performed under heparinization, it is important to consider the risk of HIT in cases of new thrombi during thrombectomy.