Editorial Type:
Article Category: Research Article
 | 
Online Publication Date: Jun 01, 2014

Comprehensive Evaluation of Culture-Negative Endocarditis with Use of Cardiac and 4-Dimensional-Flow Magnetic Resonance Imaging

MD, MEng,
PhD,
MD,
MD,
MD, and
MD
Page Range: 351 – 352
DOI: 10.14503/THIJ-12-2651
Save
Download PDF

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. / Supplemental motion image is available for Figure 1.Fig. 1. Cardiac magnetic resonance image shows the dilated ascending aorta, and significant aortic regurgitation (arrow) through the perforated bicuspid aortic valve leaflet. / Supplemental motion image is available for Figure 1.Fig. 1. Cardiac magnetic resonance image shows the dilated ascending aorta, and significant aortic regurgitation (arrow) through the perforated bicuspid aortic valve leaflet. / Supplemental motion image is available for Figure 1.
Fig. 1. Cardiac magnetic resonance image shows the dilated ascending aorta, and significant aortic regurgitation (arrow) through the perforated bicuspid aortic valve leaflet. Supplemental motion image is available for Figure 1.

Citation: Texas Heart Institute Journal 41, 3; 10.14503/THIJ-12-2651

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. / Supplemental motion image is available for Figure 2.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. / Supplemental motion image is available for Figure 2.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. / Supplemental motion image is available for Figure 2.
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. Supplemental motion image is available for Figure 2.

Citation: Texas Heart Institute Journal 41, 3; 10.14503/THIJ-12-2651

Fig. 3. Photograph shows surgical specimen of the infected, bicuspid aortic valve with leaflet perforation (arrow).Fig. 3. Photograph shows surgical specimen of the infected, bicuspid aortic valve with leaflet perforation (arrow).Fig. 3. Photograph shows surgical specimen of the infected, bicuspid aortic valve with leaflet perforation (arrow).
Fig. 3. Photograph shows surgical specimen of the infected, bicuspid aortic valve with leaflet perforation (arrow).

Citation: Texas Heart Institute Journal 41, 3; 10.14503/THIJ-12-2651

Comment

Coxiella burnetii (Q Fever) endocarditis is a rare form of endocarditis that can sometimes present as a stroke.1 Most cases of Q fever occur in individuals who have been exposed to farm animals, including buffalo. Bicuspid aortic valve, the most common congenital heart defect, is often associated with substantial morbidity, including endocarditis and aortic dilation.2 Although echocardiography, particularly TEE, typically yields adequate views of a bicuspid aortic valve and aortic root dilation, CMR affords better spatial and contrast resolution and the ability to obtain images of the entire aorta. In conventional CMR, blood flow is measured by using velocities in 2 spatial dimensions, in individual slices at specific anatomic locations.3 Using the emerging technique of 4D-flow MRI, one can view the entire 3-dimensional volume of the aorta and evaluate the complex forward and regurgitant flow jets, color-coded by velocity, over time.3,4 High-velocity, eccentric blood flow in an area of asymmetric aortic dilation or aneurysm suggests increased wall shear stress with high potential for rupture. This combination of complete anatomic visualization and evaluation of pathologic hemodynamic conditions is not feasible with echocardiography or conventional CMR. Accordingly, 4D-flow MRI might best identify those patients who are in need of urgent intervention.4 As in our patient's case, difficult clinical presentations often require multiple imaging methods for effective management.

References

  • 1.

    Raoult D
    ,
    MarrieT
    ,
    MegeJ.
    Natural history and pathophysiology of Q fever. Lancet Infect Dis2005;5(
    4
    ):219–26.

  • 2.

    Siu SC
    ,
    SilversidesCK.
    Bicuspid aortic valve disease. J Am Coll Cardiol2010;55(
    25
    ):2789–800.

  • 3.

    Markl M
    ,
    ChanFP
    ,
    AlleyMT
    ,
    WeddingKL
    ,
    DraneyMT
    ,
    ElkinsCJ
    , et al. Time-resolved three-dimensional phase-contrast MRI [published erratum appears in J Magn Reson Imaging 2003;18(3):396]. J Magn Reson Imaging2003;17(
    4
    ): 499–506.

  • 4.

    Hope MD
    ,
    HopeTA
    ,
    CrookSE
    ,
    OrdovasKG
    ,
    UrbaniaTH
    ,
    AlleyMT
    ,
    HigginsCB.
    4D flow CMR in assessment of valve-related ascending aortic disease. JACC Cardiovasc Imaging2011;4(
    7
    ):781–7.

  • Download PDF
Copyright: © 2014 by the Texas Heart® Institute, Houston
archive
archive
Fig. 1.
Fig. 1.

Cardiac magnetic resonance image shows the dilated ascending aorta, and significant aortic regurgitation (arrow) through the perforated bicuspid aortic valve leaflet.

Supplemental motion image is available for Figure 1.

Fig. 2.
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.

Supplemental motion image is available for Figure 2.

Fig. 3.
Fig. 3.

Photograph shows surgical specimen of the infected, bicuspid aortic valve with leaflet perforation (arrow).

Contributor Notes

From: Division of Cardiology, Department of Medicine (Drs. Gin, Rao, and Thadani), Department of Radiology (Drs. Dyverfeldt and Hope), and Cardiac Biomechanics Laboratory (Dr. Chitsaz), University of California, San Francisco, San Francisco, California 94143; and Division of Cardiology, Department of Medicine (Dr. Thadani), California Pacific Medical Center, San Francisco, California 94115

Dr. Thadani's secondary affiliation is now the Division of Cardiology, Department of Medicine, Kaiser Permanente, South San Francisco, California.

Address for reprints: Samir R. Thadani, MD, Division of Cardiology, University of California, San Francisco, 505 Parnassus Ave., Box 0214, San Francisco, CA 94143-0214; E-mail: samir.thadani@ucsf.edu

Section Editor: Raymond F. Stainback, MD, Department of Adult Cardiology, Texas Heart Institute, 6624 Fannin St., Suite 2480, Houston, TX 77030