Cardiac imaging in common arterial trunk

Abstract

The diagnosis of common arterial trunk (truncus arteriosus communis) is suspected when the chest radiogram shows a combination of cardiomegaly with oval configuration, increased pulmonary vascularity, narrow superior mediastinum, concave pulmonary arterial segment and right aortic arch in a patient with cyanosis and cardiac murmur. In most cases, echocardiography can provide complete morphological information of common arterial trunk and its associated lesions, although magnetic resonance imaging can provide more objective images with clearer visualization of the adjacent mediastinal structures including thymus. Cardiac catheterization for calculation of pulmonary vascular resistance should be performed for patients older than 3 months. When catheterization is performed, angiograms are obtained for a better understanding of the pathology. The ventricular septal defect and overriding common arterial trunk are best shown in long axis view. The dominant vessel arising from the common arterial trunk is the aorta in the majority of cases. When the ascending aorta is smaller than the pulmonary artery, associated interruption of the aortic arch should be suspected. The origin of the pulmonary artery from the common arterial trunk can be seen in right and left anterior oblique views. Preferred echocardiographic views for evaluation of the pulmonary arterial anatomy are high-parasternal and suprasternal views. Truncus arteriosus can be diagnosed in the fetus by using high-resolution sonography. For fetal screening of common arterial trunk, a three-vessel view is very helpful. It is an orthogonal transverse view of the fetal upper mediastinum where the main pulmonary artery, ascending aorta and superior vena cava are arranged in a line. When there are only two vessels in the three-vessel view, common arterial trunk is suspected. Once the diagnosis of common arterial trunk is made in the fetus, fluorescent in situ hybridization (FISH) should be performed to exclude del 22(q11) or CATCH 22 syndrome.