Pulse oximetry screening (POS) for critical congenital heart diseases (CCHD) could identify 90% of these infants. However, this approach is not designed to detect cardiac defects without hypoxemia, especially congenital malformations of aorta (CMoA). More than 60% of CMoA was late diagnosed.

Infants with CMoA were supposed to present with blood pressure (BP) gradient between four limbs. But a large sample size retrospective study of four-limb BP screening showed a negative result. The possible reason is that this study ran in population with a very low risk of CMoA. Whether four-limb BPs measurement could be used in infants with high risk of congenital malformation of aorta is still to be determined.

The investigators retrospectively collected four-limb BPs, which was prospectively measured, in infants with high risk of CMoA. These data were divided into two groups, the discovery group and the validation group. The best cutoff of four-limb BP gradient was generated by Youden Index. The BP gradients by age were analyzed. Pre-operative hypotension and post-operative hypertension were also analyzed.

Inclusion Criteria:

• Infants admitted to the Guangdong Provincial People's Hospital between January 1st, 2013 and December 31st, 2019, who were suspected as having congenital heart disease, were enrolled in the study.

Exclusion Criteria:

• Infants without four-limb blood pressures measurement or without echocardiogram and cardiac computed tomography results were excluded.

Infants admitted to the Guangdong Provincial People's Hospital between January 1st, 2013 and December 31st, 2019, who were suspected as having congenital heart disease, were enrolled in the study. Four-limb BPs in infants of confirmed or suspected CCHD admitted at our hospital were prospectively collected at admission following the Pediatric Department protocol for CCHD infants in which all infants with high risk of CCHD, defined as confirmed or suspected CCHD by clinical teams, were screened by measuring four-limb BPs by certificated nurses. Suspected CCHD was defined as unreasonable low SpO2, cyanosis, murmur, suspected CHD by prenatal ultrasound or postnatal echocardiography at other hospitals, and unexplained poor cardiac output.