History
A 22-month-old girl had a cardiac murmur, which had been detected during a physical examination after birth. Her physical development was significantly behind children of the same age and she was very prone to catching colds. An echocardiogram revealed an atrial septal defect (ASD), an enlarged right heart and a total anomalous pulmonary venous connection (TAPVC). She was admitted for surgical repair and a pulmonary CT angiography (CTA) was requested for preoperative evaluation.
Diagnosis
CTA images showed an ASD, measuring 17.6 x 19.6 mm2 in size. The right atrium (RA) and the right ventricle (RV) were enlarged. Bilateral inferior pulmonary veins (IPVs) returned to the left atrium (LA), and the proximal left IPV was compressed by the descending aorta (DA), causing a severe obstruction. The left superior pulmonary vein (LSPV) drained into the left innominate vein (LIV), through a vertical vein, and the right superior pulmonary vein (RSPV) drained into the superior vena cava (SVC) in two separate branches. No abnormalities were seen in the pulmonary arteries (PA), in the aorta and in the tracheobronchial tree. The origins and courses of both coronary arteries appeared normal. Subsequently, the patient underwent surgery – the ASD was repaired and the RSPV was re-directed to LA. A postoperative echocardiogram confirmed the surgical success. The patient recovered uneventfully and was discharged 7 days after the operation.
Figs. 1: An axial MIP image (Fig. 1a) shows an ASD (asterisk), enlarged RA and RV, bilateral IPVs returning to the LA and a severe proximal left IPV obstruction resulting from compression by the DA (arrow). An oblique MIP image (Fig. 1b) shows normal origins and courses of both coronary arteries.
Courtesy of Department of Radiology, The Sixth Medical Center of PLA General Hospital, Beijing, P. R. China
Fig. 2: cVRT images show the RSPV draining into the SVC in two separate branches (Figs. 2a & 2b, arrows), and the LSPV draining into the LIV through a vertical vein (Figs. 2c & 2d, arrows). Bilateral IPVs return to the LA.
Courtesy of Department of Radiology, The Sixth Medical Center of PLA General Hospital, Beijing, P. R. China
Fig. 3: A cVRT image shows a posterior overview of the PAPVC, the PA, the aorta and the tracheobronchial tree. The compression of the proximal left IPV by the DA is also shown (arrows).
Comments
Pulmonary veins (PV), carrying oxygen-rich blood, should return to the LA. Rarely, an anomalous connection of some (PAPVC) or all (TAPVC) PVs can occur, draining into the RA or its tributaries. TAPVC and PAPVC may occur as isolated lesions or can be associated with other cardiac defects, mostly with an ASD. Corrective surgery is indicated in all patients with TAPVC, while conservative management with close follow-ups can be applied in patients with PAPVC, unless development of symptoms, significant left to right shunt or evidence of right ventricular dysfunction are present. Echocardiography is the first diagnostic tool in the preoperative evaluation and follow-up of congenital heart disease (CHD). However, the diagnosis may be limited due to poor acoustic windows for the characterization of extracardiac anatomy and complex cases, [1] such as this case. An MR examination on children is time-consuming, especially in complex cases, requiring sedation with MR-compatible equipment. This case is performed on a Dual Source CT scanner, SOMATOM Force, which provides a high spatial and temporal resolution. The patient is scanned at free breathing, without sedation, using an innovative spiral scanning technique – “Turbo Flash mode” with prospective ECG triggering. The acquisition of the entire thorax is performed in just 0.18 s. A lower tube voltage setting of 70 kV is selected by an automated feature of the system – CARE kV, adjusting the kV to the individual patient, the system capabilities and the clinical task. This enhances the contrast-to-noise ratio, prompting a potential reduction of the amount of contrast agent needed (12 mL) as well as the radiation dose (0.54 mGy). Another notable feature is the superb three-dimensional (3D) capability using cinematic volume rendering technique (cVRT), which allows for a lifelike visualization of cardiovascular structures. This is especially useful for preoperational evaluation, communication between physicians and surgical planning. As shown in this case, CTA is a reliable, non-invasive imaging method for the diagnosis of CHD complementary to echocardiography, with its capability of depicting the anatomical details of the heart chambers as well as the associated vascular anomalies in a single scan.
Examination Protocol