A 54-year-old woman with an implantable cardioverter-defibrillator was admitted because of convulsion. Previously, she had suffered methicillin-resistant Staphylococcus aureus (MRSA) sepsis induced by a central venous catheter. Despite removal of the central venous catheter and administration of vancomycin, fever and increased C-reactive protein level persisted. MRSA had probably infected the implantable cardioverter-defibrillator system. Gallium scintigraphy showed accumulation at the right subclaviculan area, although local inflammatory signs were absent. Intravascular ultrasonography demonstrated intravenous vegetation at the bifurcation of the right subclavian vein and right internal jugular vein. Antibiotic therapy was not curative, so she underwent extirpation of the intravenous vegetation, which cured the systemic inflammation. Intravascular ultrasonography was useful to differentiate central venous catheter-related infection from implantable cardioverter defibrillator-related infection.