Clinical History A 51-year-old woman with a history of supravalvular aortic stenosis presented with new onset exertional dyspnea. Her history included an aortotomy at the age of 5, and, at the age of 45, a Ross procedure, including composite aortic root replacement with a pulmonary homograft and pulmonic valve replacement with a 23 mm pulmonary homograft. She refused a cardiac MRI, citing severe claustrophobia during a prior experience at another hospital.
Findings Cardiac CT was performed for anatomic survey and quantitative assessment of biventricular function. The exam found residual post-surgical supravalvular aortic stenosis with collaterals (Figure 1), post-surgical stenosis of the pulmonic trunk (Figure 2), non-obstructive coronary artery disease (CAD) without evidence of coronary anomalies (Figure 3), and mild concentric left ventricular hypertrophy with preserved biventricular systolic function (Figure 4). The resting right ventricular (RV) ejection fraction was 47%, and the resting left ventricular (LV) ejection fraction was 62%. The exam also showed close high apposition of anterior mediastinal structures to the posterior midline and left sternum, a finding of great significance for repeat sternotomy planning.
(Click on image to enlarge)
Figure 1:Oblique maximum intensity projection image shows a 57% area luminal narrowing supravalvular aortic stenosis (green arrow) and collateral vessels secondary to supravalvular aortic stenosis (red arrow). [Ao = Aorta, RA= Right Atrium].
Figure 2: Concurrent coronary CTA (C) shows a calcified plaque (white arrowhead), excludes significant coronary anomalies and obstructive CAD, and shows close apposition of anterior mediastinal structures to the posterior midline and left sternum (blue arrowhead). [RCA= Right Coronary Artery, LM= Left Main artery, LCx= Left Circumflex artery, LAD= Left Anterior Descending artery].
Figure 3: Short axis view of the main pulmonary artery trunk and the aorta shows 47% luminal narrowing (white arrow) of the pulmonary artery. [PA= pulmonary artery, Ao= Aorta].
Figure 4:Functional dataset from the retrospective acquisition reveals preserved biventricular systolic function.
Discussion Although the primary uses for cardiac CT include anatomic imaging of the chest and coronary arteries, dual-source cardiac CT has superior temporal resolution that allows functional imaging [1, 2]. When our patient refused a cardiac MRI, cardiac CT provided the necessary quantitative assessment of RV systolic function. The total radiation dose for this comprehensive exam was 2.1 mSv. As the population of adults with congenital heart disease grows, mechanisms to study the right ventricle will become increasingly important.3D-transthoracic cardiac ultrasound (TTE) has the ability to quantitatively assess RV systolic function, but is not currently widely available . Cardiac MRI and CT provide anatomic and functional assessment of biventricular function in these patients, in addition to offering images for pre-operative planning.
Quantification of global left ventricular function: comparison of multidetector computed tomography and magnetic resonance imaging. A meta-analysis and review of the current literature. van der Vleuten PA et al. Acta Radiol. 2006; 47:1049-57.
Right ventricle function assessment by MDCT. Dupont MV et al. Am J Roentgenol. 2011; 196:77-86.
Normal values of right ventricular size and function by real-time three-dimensional echocardiography: comparison to cardiac magnetic resonance imaging. Gopal AS et al. J Am Soc Echocardiogr 2007; 20:445-55.
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