Setting and Design: Retrospective observational cohort study in the State of Johor, Malaysia.

Subjects and Methods: All infants born between January 2006 and December 2015 with a diagnosis of CCHD, defined as infants with duct-dependent lesions or cyanotic heart disease who may die without early intervention. The late diagnosis was defined as a diagnosis of CCHD after 3 days of age.

Results: Congenital heart disease was diagnosed in 3557 of 531,904 live-born infants and were critical in 668 (18.7%). Of 668, 347 (52%) had duct-dependent pulmonary circulation. The birth prevalence of CCHD was 1.26 (95% confidence interval: 1.16-1.35) per 1000 live births, with no significant increase over time. The median age of diagnosis was 4 days (Q1 1, Q3 26), with 61 (9.1%) detected prenatally, and 342 (51.2%) detected late. The highest rate of late diagnosis was observed in coarctation of the aorta with a rate of 74%. Trend analysis shows a statistically significant reduction of late diagnosis and a significant increase in prenatal detection. However, Cox regression analysis shows the timing of diagnosis does not affect the outcome of CCHD.

METHODS: Immunohistochemistry was performed on GCA temporal artery biopsy specimens (n = 12) and aortas (n = 10) for detection of YKL-40, its receptor interleukin-13 receptor α2 (IL-13Rα2), macrophage markers PU.1 and CD206, and the tissue-destructive protein matrix metalloproteinase 9 (MMP-9). Ten noninflamed temporal artery biopsy specimens served as controls. In vitro experiments with granulocyte-macrophage colony-stimulating factor (GM-CSF)- or macrophage colony-stimulating factor (M-CSF)-skewed monocyte-derived macrophages were conducted to study the dynamics of YKL-40 production. Next, small interfering RNA-mediated knockdown of YKL-40 in GM-CSF-skewed macrophages was performed to study its effect on MMP-9 production. Finally, the angiogenic potential of YKL-40 was investigated by tube formation experiments using human microvascular endothelial cells (HMVECs).

RESULTS: YKL-40 was abundantly expressed by a CD206+MMP-9+ macrophage subset in inflamed temporal arteries and aortas. GM-CSF-skewed macrophages from GCA patients, but not healthy controls, released significantly higher levels of YKL-40 compared to M-CSF-skewed macrophages (P = 0.039). In inflamed temporal arteries, IL-13Rα2 was expressed by macrophages and endothelial cells. Functionally, knockdown of YKL-40 led to a 10-50% reduction in MMP-9 production by macrophages, whereas exposure of HMVECS to YKL-40 led to significantly increased tube formation.

METHODS: A comprehensive search of peer reviewed journals was completed based on the key words, "Circumflex aorta," "Circumflex retro-esophageal aorta" and "circumflex arch" using Google scholar, Scholars Portal Journals and PubMed. The reference section for each article found was searched to obtain additional articles. Literature on the circumflex aorta was reviewed starting from the embryogenesis to the latest management strategies.

RESULTS: Right circumflex aorta is more prevalent compared to left circumflex aorta. It can occur in isolation or in association with other intracardiac lesions. Mainly presents in children, however reported in adults too. The presentation may vary from asymptomatic lesion to acute respiratory distress secondary to airway compression. Computerized tomography (CT) and magnetic resonance imaging (MRI) are important tools in delineating the vascular anatomy. Aortic uncrossing is the definitive procedure. However, the role of concomitant tracheobronchopexy is emerging. Native tissue-to-tissue anastomosis is commonly preferred, but cases of extra-anatomic grafts are reported.