Unrepaired persistent truncus arteriosus in an adult

A 27-year-old female patient came to the hospital complaining of a mild edema developing in both of her legs, for no obvious reason, over the past two weeks. Otherwise, she reported coughing with white phlegm, occasional dizziness and headaches as well as exertional dyspnea that could be relieved by rest. The physical examination revealed both central and peripheral cyanosis. A previous diagnosis of “congenital heart disease” in her childhood was reported, however no details could be provided. A chest CT with contrast was requested for further evaluation.

CT images revealed a common arterial trunk, overriding a high ventricular septal defect (VSD), shared by the ascending aorta (AA) and the main pulmonary artery (MPA), compatible with truncus arteriosus (TA) Collett & Edwards type I or Van Praagh type A1. The MPA, originating from the left lateral aspect of the common trunk, divided into the right and the left pulmonary arteries (PA). Signs of central PA dilatation, tapering of peripheral PA, cardiomegaly with biventricular hypertrophy and marked enlargement of the right atrium and left ventricle, along with a mosaic pattern of attenuation in the lungs, consistent with severe chronic pulmonary hypertension, were visualized. The aortic arch and the brachiocephalic arteries showed no abnormalities. The left coronary artery (LCA) originated off the right-posterior aspect of the TA, coursing between the left atrium and the TA. The origin and the course of the right coronary artery (RCA) appeared normal. Subsequently, an echocardiography examination confirmed the CT findings and additionally revealed a mild regurgitation of all four valves. The patient was only treated medically, due to her pulmonary condition, and was discharged with noticeable improvement one week later.

Fig. 2: A coronal MPR image shows a mosaic pattern of attenuation in the lungs and cardiomegaly.

Persistent truncus arteriosus (PTA), which is often referred to simply as TA, is a rare congenital heart disease. A TA is an embryological structure which should properly divide itself into the aorta and the pulmonary trunk. Failure to do so results in only one arterial trunk arising from the heart, usually overriding a VSD, providing mixed oxygenated and carbonized blood to both the aortic and pulmonary circulation. Early surgical correction is the treatment of choice and can guarantee long-term survival since over 80% of infants with TA die within their first life year. [1] [2] In rare cases, a person with TA survives infancy without surgical repair and lives into adulthood, such as the present case. However, these patients have a high risk for pulmonary hypertension and the Eisenmenger syndrome. Echocardiography is the primary imaging examination to comprehend dynamic blood flow and valve function; whereas the strength of CT lies in the ability to describe anatomical details, such as the origin and the course of the coronary arteries and to determine the exact course and relation of the greater arteries to each other, both mandatory for exact presurgical planning. In the present case, the use of only 70 kV tube voltage was feasible due to the patient’s body habitus. This lower kV setting has the advantage of an increased contrast-to-noise ratio in CT angiography with a lower radiation dose compared to a 120 kV protocol. Furthermore, the amount of required contrast material can be significantly reduced (30 mL). Cinematic volume rendering allows for a realistic 3D display of the anatomy with improved depth and shape perceptions. This enables an optimal overview of the anatomical structures which is important for treatment planning, communication with the patient and between physicians.