A vascular ring: right aortic arch and descending aorta with left ductus arteriosus

Methodology of echocardiographic analysis of morphological variations of the aortic arch and its branches in children - own experience

We wish to share our experience in echocardiographic assessment of the course of the aortic arch, illustrating it with multiple examples of the majority of possible variants. The course of the aortic arch and its branches may be visualized using high parasternal and suprasternal views in sagittal and transverse planes. It is hardly ever possible to visualize the entire aortic arch on a single ultrasonographic section, particularly in the case of pathological variations. Echocardiography should be performed in a dynamic mode, as in the case of CT angiography or magnetic resonance, by gradually moving the ultrasound beam and following the position of subsequent aortic segments and branches on the screen. Due to disturbances in ultrasound propagation caused by air-containing tissues, such as the trachea, bronchi and lungs as well as bones (sternum and ribs), each evaluation of the entire arch requires the use of a higher number of echocardiographic views. The presented data show that echocardiographic detection of the main details of aortic arch anomalies is possible in practically all cases. In the case of patients considered for surgical treatment, all unresolved issues should be clarified with CT angiography or MRI, enabling 3 dimensional reconstruction of vessels and other thoracic structures. Knowledge of the main elements of an abnormal arch is crucial for proper planning of this type of examination; therefore the diagnostic process should be always initiated with echocardiography. Echocardiography is often sufficient to answer all clinical questions and finalize the diagnostic process.

We wish to share our experience in echocardiographic assessment of the course of the aortic arch, illustrating it with multiple examples of the majority of possible variants. The course of the aortic arch and its branches may be visualized using high parasternal and suprasternal views in sagittal and transverse planes. It is hardly ever possible to visualize the entire aortic arch on a single ultrasonographic section, particularly in the case of pathological variations. Echocardiography should be performed in a dynamic mode, as in the case of CT angiography or magnetic resonance, by gradually moving the ultrasound beam and following the position of subsequent aortic segments and branches on the screen. Due to disturbances in ultrasound propagation caused by air-containing tissues, such as the trachea, bronchi and lungs as well as bones (sternum and ribs), each evaluation of the entire arch requires the use of a higher number of echocardiographic views. The presented data show that echocardiographic detection of the main details of aortic arch anomalies is possible in practically all cases. In the case of patients considered for surgical treatment, all unresolved issues should be clarified with CT angiography or MRI, enabling 3 dimensional reconstruction of vessels and other thoracic structures. Knowledge of the main elements of an abnormal arch is crucial for proper planning of this type of examination; therefore the diagnostic process should be always initiated with echocardiography. Echocardiography is often sufficient to answer all clinical questions and finalize the diagnostic process.

Non-invasive diagnosis of aortic arch anomalies in children - 15 years of own experience

Aim

To summarize our experience in echocardiographic diagnosis of aortic arch anomalies in pediatric patients.

Materials and methods

A retrospective assessment of echocardiographic findings in Echo-Lab patients of the Pediatric Cardiac Surgery Department, who were diagnosed with an anomalous aortic arch between 2003 and 2018.

Results

The diagnosis of an abnormal course of the aortic arch and/or its branches was established in 115 children aged between 4 days and 17 years. The following types of anomalies were detected: left aortic arch with aberrant right subclavian artery in 42 patients; right aortic arch with left brachiocephalic trunk in 14 patients; right aortic arch, aberrant left subclavian artery in 36 patients; double aortic arch in 14 patients; and other, more complex types in 9 patients. The main elements of defects were correctly identified by echo in all cases. We decided to additionally perform computed tomography angiography in 32 patients to clarify all details necessary to qualify patients for surgery and establish the surgical plan.

Conclusions

1. Echocardiography strictly following the pre-determined protocol has 100% sensitivity in the detection of basic elements of aortic arch anomaly and is a perfect tool for diagnostic process initiation. 2. Since it is not possible to visualize all anatomic details, the qualification for surgery should by based on computed tomography angiography or cardiac magnetic resonance imaging, which precisely visualize both abnormal vessels and compressed structures.

Changes in topographical relation between the ductus arteriosus and left subclavian artery in human embryos: a study using serial sections

At birth, the ductus arteriosus (DA) merges with the aortic arch in the caudal side of the origin of the left subclavian artery (ltSCA). Since the SCA (seventh segmental arteries) were fixed on the levels of the seventh cervical-first thoracic vertebral bodies, the confluence of the DA should migrate caudally toward the lower level. We aimed to describe the changing topographical anatomy of the DA and SCA using serial sections. First, we examined serial sagittal sections of 11 embryos (Carnegie stage 15-18), but the specimens were clearly divided into 2 groups with and without the lower confluence of the DA. Next, we examined serial horizontal sections of 40 specimens (Carnegie stage 14-16) and we chose 5 specimens (CRL 11 mm, 3 specimen; 1, 14 mm; 1, 15 mm) including the DA near (within 1-vertebral segment from) the ltSCA. The final approach of the DA occurred during the heart descent in which the apex of the heart migrated from the level of the first to the fourth thoracic vertebral body. Thus, the DA reached the SCA level before establishment of the heart descent. The right aortic arch maintained its entire course in 2 of the 5 specimens. Therefore, the positioning of the DA along the left aortic arch might occur independently of degeneration of the right arch. Notably, the tracheal bifurcation level was higher when the DA-ltSCA distance was greater. A contribution of the increased pulmonary volume was suggested for the final approach of the DA.

Pathogenesis of solitary right aortic arch: a mass effect hypothesis based on observations of serial human embryonic sections

In general, solitary right aortic arch carries the left-sided ductus arteriosus communicating between the left subclavian and pulmonary arteries or the right-sided ductus connecting the descending aorta to the left pulmonary artery. Serial sections of fifteen 5- to 6-week-old embryos and ten 8- to 9-week-old fetuses suggested that the pathogenesis was unrelated to inversion due to dysfunction in gene cascades that control the systemic left/right axis. With inversion, conversely, the ductus or the sixth pharyngeal arch artery should connect to the right pulmonary artery. The disappearance of the right aortic arch started before the caudal migration of the aortic attachment of the ductus. Sympathetic nerve ganglia developed immediately posterior to both aortae, with a single embryonic specimen showing a large ganglion at the midline close to the union of the aortic arches. These ganglia may interfere with blood flow through the distal left arch, resulting in the ductus ending at the descending aorta behind the oesophagus. In another fetus examined, a midline shift of the ductus course resulted in the trachea curving posteriorly. Therefore, solitary right arch is likely to accompany abnormalities of the surrounding structures. The timing and site of the obstruction should be different between types: an almost midline obstruction near the aortic union needed for the development of the left-sided ductus and a distal obstruction near the left subclavian arterial origin needed for the development of the right-sided ductus. A mass effect of the sympathetic ganglia may explain the pathogenesis of any type of anomalous ductus arteriosus shown in previous reports of the solitary right arch.

Vascular rings: a practical approach to imaging diagnosis

Vascular ring is a term given to a combination of vascular and often ligamentous structures that encircle the trachea and esophagus. The diagnosis can be difficult because clinical symptoms can be variable and nonspecific, and because vascular arrangements that result in vascular rings in some patients do not form vascular rings in others. The clinical manifestations comprise a spectrum ranging from no symptoms to feeding difficulties, repeated infections, and life-threatening respiratory compromise. The diagnosis of vascular ring can be made by various imaging modalities. Therefore it is imperative that pediatric radiologists be familiar with the anatomic variants that can result in a symptomatic ring needing surgical repair, their imaging appearance and the appropriate imaging algorithm. The goals of this manuscript are to describe common and uncommon types of vascular rings, to simplify the differential diagnosis, and to outline the imaging options for accurate diagnosis.