Cardiac rhythm abnormalities during intravenous immunoglobulin G infusion for treatment of thrombocytopenia

Purpose: Several side effects of intravenous immunoglobulin G (IVIG) therapy are known, but it has never been reported to be associated with cardiac rhythm abnormalities other than sinus tachycardia. Patients and Methods: We describe the development of cardiac dysrhythmias during intravenous immunoglobulin G infusion in two children with thrombocytopenia. One of the patients had a history of supraventricular tachycardia, and the other had evidence suggestive of preexisting long QT syndrome. Conclusion: Cardiac rhythm abnormalities may be exacerbated in individuals with preexisting cardiac problems by IVIG infusion, and such patients should be monitored closely during IVIG administration.