Comprehensive evaluation of culture-negative endocarditis with use of cardiac and 4-dimensional-flow magnetic resonance imaging.

A 42-year-old, otherwise healthy man with exposure to domesticated buffalo presented with a 3-day history of intermittent headaches and word-finding difficulties. Magnetic resonance images (MRI) revealed an ischemic infarct in the left temporal lobe. A high-pitched, intense, pandiastolic murmur was detected at the right upper sternal border. A transthoracic echocardiogram showed moderate-to-severe aortic insufficiency. A transesophageal echocardiogram (TEE) showed a bicuspid aortic valve with possible leaflet perforation. Cardiac magnetic resonance (CMR) images confirmed regurgitation through a perforated bicuspid leaflet, excluded an abscess, and revealed a dilated ascending thoracic aorta (Fig. 1). The eccentric regurgitant jet and asymmetric aortic dilation were best seen by means of time-resolved, 3-dimensional, phase-contrast MRI (4-dimensional [4D]-flow MRI), with use of instantaneous streamline and dynamic pathline views of blood flow (Fig. 2). The patient's blood cultures remained negative; however, serologic studies subsequently were positive for Coxiella burnetii, suggesting a chronic, active infection. The patient was treated with doxycycline and hydroxychloroquine and underwent successful surgical aortic root and valve replacement (Fig. 3). Fig. 1. Cardiac magnetic resonance image shows the dilated ascending aorta, and significant aortic regurgitation (arrow) through the perforated bicuspid aortic valve leaflet. Fig. 2. Four-dimensional-flow magnetic resonance imaging of the thoracic aorta. Streamlines are color-coded for velocity and reveal instantaneous flow across the aortic valve (arrow) and in the aorta during A) systole and B) diastole. Fig. 3. Photograph shows surgical specimen of the infected, bicuspid aortic valve with leaflet perforation (arrow).