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Figure 13-118: Parasternal long-axis (A) and apical four-chamber (B) images of tetralogy of Fallot. The right ventricle (RV) is enlarged, and a large VSD is present. The aorta (AO) overrides the interventricular septum. LV = left ventricle. (Courtesy of Reinaldo W. Beyer, MD.)

Although double-outlet tight ventricle (DORV) shares several clinical characteristics with tetralogy of Fallot (VSD and anterior aortic displacement are invariably present, and pulmonic valvular stenosis and ASD are common in both), it is morphologically distinct (Fig. 13-119). Normal continuity of the posterior aortic wall with the anterior mitral valve leaflet (always present in tetralogy of Fallot) is absent in DORV, and an interposed mass of fibrous tissue between the left atrium and the nearest great vessel is seen on 2D imaging.593,594 In addition, the great vessels may be transposed in DORV, resulting in a characteristic side-by-side appearance of the aorta and PA on parasternal short-axis images.595

Figure 13-119: Parasternal long-axis image of double-outlet right ventricle. A large VSD is present (small arrow) and the normal continuity between the posterior aortic wall and the anterior mitral leaflet is absent. Fibrous tissue is seen (large arrow) between the left atrium (LA) and the nearest great vessel (in this case, the pulmonary artery (PA). LV = left ventricle.

Figure 13-119: Parasternal long-axis image of double-outlet right ventricle. A large VSD is present (small arrow) and the normal continuity between the posterior aortic wall and the anterior mitral leaflet is absent. Fibrous tissue is seen (large arrow) between the left atrium (LA) and the nearest great vessel (in this case, the pulmonary artery (PA). LV = left ventricle.

Echocardiography has become a valuable tool for detection, management, and postoperative follow-up of patients with transposition ofthe great arteries. Attention to the anatomic rules mentioned earlier is essential for accurate diagnosis of both D (classic) and L ("congenitally corrected") transposition. In D-transposition, the aorta arises from the RV, the PA arises from the LV, and one or more obligatory shunts are present. With L-transposition, the morphologic right and left ventricles are switched, and associated anomalies such as VSD and pulmonic stenosis are common. In both types of transposition, the normal echocardiographic orientation of the great vessels on parasternal short-axis images (a sausage-shaped RVOT and PA draped over a circular aorta) is no longer present, and the two great vessels are typically side by side and parallel (Fig. 13-120).596,597 In general, the aorta is anterior and to the right of the PA in D-transposition and anterior and to the left in L-transposition. Both TTE and TEE are an important part of continuing care after surgical repair or palliation of transposition; they can detect valvular regurgitation, outflow tract narrowing, and stenosis of the atrial baffle systems used to palliate D-transposition surgically.598-600

Parts The Pulmonic Valve
Figure 13-120: Transverse transesophageal image through the semilunar valves in L-transposition. The aortic valve (A) is anterior and to the left of the pulmonic valve (P). LA = left atrium.

Truncus arteriosus is a rare anomaly characterized by a large VSD, a single semilunar valve, and a single great vessel that divides into the ascending aorta and PA.601,602 Ultrasound imaging can determine the anatomy of the great vessels and assist in defining the various subsets of truncus arteriosus.

Coarctation of the aorta is associated with a bicuspid aortic valve and is best visualized from the suprasternal position. 2D imaging may identify the site of coarctation, but the natural mild curving of the descending aorta can occasionally lead to a false-positive diagnosis. Clear visualization of narrowing in the proximal descending aorta with poststenotic dilatation, however, is pathognomonic of coarctation.603,604 Doppler interrogation from the suprasternal notch demonstrates increased systolic velocity in the descending aorta and may also reveal a persistent flow gradient throughout diastole in cases of severe coarctation Fig. 13-121).Color imaging often displays flow acceleration and aliasing proximal to the site of coarctation. The maximum velocity through the coarctation can be used to estimate the pressure gradient, and this measurement can be particularly valuable for the detection of restenosis after surgical repair or percutaneous balloon aortic dilatation.606,607

Supravalvular aortic stenosis, either isolated or associated with Williams syndrome (Chap. 10), is generally imaged best from the suprasternal and superior parasternal positions. Echocardiography reveals either an hourglass-shaped stenosis of the aorta above the sinuses of Valsalva, diffuse hypoplasia of the ascending aorta, or a focal fibrous ridge at the sinotubular junction.608 Doppler imaging can help estimate the gradient across the stenosis, and marked aliasing of color-flow imaging in the ascending aorta should raise suspicion of the diagnosis. Thickening of the aortic valve leaflets and stenoses of the coronary ostia are important associated findings that may be detectable by echocardiography.

Ventricular Outflow Tract and Semilunar Valve Abnormalities

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