Thrombin Injection to Treat an Iatrogenic Internal Mammary Artery Pseudoaneurysm

A 71-year-old female presented to the emergency room eight weeks status post open heart surgery for aortic valve replacement with right-sided chest wall pain and swelling. Computed tomographic (CT) angiography demonstrated a hyperattenuating structure arising from the right internal mammary artery surrounded by a heterogeneously-attenuating fluid collection in the anterior right chest wall, compatible with a right internal mammary artery pseudoaneurysm with surrounding chest wall hematoma. Follow up color Doppler ultrasound confirmed the diagnosis. Under direct ultrasound visualization, we injected four hundred units of thrombin into the neck of the pseudoaneurysm using a 25-gauge spinal needle. Post-injection imaging demonstrated a successful cessation of flow within the pseudoaneurysm sac.