Eva Niv, Avishay Elis, Rivka Zissin, Timna Naftali, Ben Novis, Michael Lishner

PRESENTING FEATURES: A 53-year-old woman with a prosthetic aortic valve presented to an outside hospital with acute onset of severe right leg pain and inability to move her right toes. She was found to have an embolus to the right femoral artery. Pathology specimens showed gram-positive cocci in the embolus, and two sets of blood cultures were positive for Enterococcus faecalis. The patient was transferred after a right femoral artery embolectomy with the presumed diagnosis of prosthetic valve endocarditis. The patientʹs past medical history was notable for aortic stenosis, coronary artery disease, and colonic polyps. She underwent aortic valve replacement and coronary artery bypass graft surgery in October 2002. In June 2003, the patient had an episode of E. faecalis endocarditis that was treated with an 11-week course of ampicillin and an 8-week course of gentamicin. A transesophageal echocardiogram at that time showed a 3-mm vegetation on the prosthetic aortic valve, without evidence of a valve ring abscess, and a probable 1-mm vegetation on the native mitral valve. At this time, the patient was also found to have severe atherosclerosis of the aortic arch, with a large mobile thrombus. The patient had undergone colonoscopy with polypectomy in March 2003, 3 months prior to her initial presentation with endocarditis. She did not recall if she took prophylactic antibiotics prior to the procedure. Her medications when she was transferred to The Johns Hopkins Hospital included ampicillin, metoprolol, lisinopril, aspirin, and unfractionated heparin. The patient denied any use of tobacco, alcohol, or illicit drugs. Her family history was notable only for coronary artery disease in parents and siblings. On physical examination, the patient was a middle-aged, moderately obese woman. She had a temperature of 36°C, heart rate of 64 beats per minute, blood pressure of 109/56 mm Hg, respiratory rate of 18 breaths per minute, and an oxygen saturation of 98% while breathing room air. Her dentition was normal. Jugular venous pressure and carotid upstrokes were normal. Cardiovascular examination revealed a normal S1 with a mechanical S2 and a harsh III/VI systolic murmur at the right upper sternal border with radiation to the carotids. Pulmonary and abdominal examinations were normal. The patient had normal radial pulses bilaterally, a diminished right dorsalis pedis pulse, and a normal left dorsalis pedis pulse. Her right femoral operative site had no inflammation and was healing normally. Initial laboratory values were unremarkable, including a normal white blood cell count of 5.2 × 103/μL. The patientʹs C-reactive protein was minimally elevated at 4.2 mg/dL. Bacterial blood cultures taken at our institution had no growth. On admission, the patient was continued on intravenous ampicillin; intravenous minocycline was added. Neither transthoracic nor transesophageal echocardiogram showed evidence of a mass, a vegetation, a perivalvular abscess, or atheromatous disease in the aortic arch. A computed tomographic (CT) scan of the thorax with contrast demonstrated no evidence of a mediastinal abscess and showed minimal bilateral atelectasis. A CT scan of the abdomen and pelvis with contrast suggested a pseudoaneurysm of the right common femoral artery but no evidence of intra-abdominal, pelvic, or thigh abscess. Thoracic magnetic resonance angiogram and contrast arteriogram of the aortic arch were performed (Figure 1 and Figure 2). What is the diagnosis?