Abstract: Background： Objective：Transthoracic echocardiography (TTE) is an important examination method for preoperative and postoperative follow-up assessment of absent right pulmonary artery (UARPA). Reports on its echocardiographic features and changes in pulmonary artery pressure before and after surgery are relatively rare. Design：Case series reports. Methods：A retrospective collection of consecutive cases diagnosed with UARPA at Guangzhou Women and Children's Medical Center, Guangzhou Medical University was conducted from January 2018 to January 2024. Data on patients' gender, age, weight, clinical manifestations, preoperative and postoperative auxiliary examinationResults：, treatment, follow-up duration, and follow-up outcomes were extracted from the hospital's medical record system and summarized. Main outcome measures：Echocardiographic features before and after surgery. Results：A total of 37 pediatric patients with UARPA were included in this study, consisting of 18 males and 19 females. The median age was 7 months (ranging from 1 day to 6 years and 9 months), with 25 cases (67.6%) under the age of 1 year. The median body weight was 6.4 kg (range: 2.7-22.1 kg). The main clinical manifestations included tachypnea (21.6%), recurrent respiratory infections (18.9%), and recurrent hemoptysis and cyanosis (16.2% each). Among the 37 cases, 27 (73.0%) had associated congenital heart defects, with the most common being atrial septal defect (ASD) or patent foramen ovale (PFO) in 23 cases (62.2%) and patent ductus arteriosus (PDA) in 12 cases (32.4%). Additionally, one patient (2.7%) had an aberrant right subclavian artery. Pulmonary hypertension was observed in 19 patients (51.4%). Echocardiographic examination revealed that the right pulmonary artery was absent at the distal main pulmonary artery, with the main pulmonary artery continuing directly into the left pulmonary artery. The right lung received blood supply through PDA or collateral vessels originating from the aorta and its arch branches. Among the 37 patients, 27 (73.0%) underwent right pulmonary artery reconstruction surgery, with a median surgical age of 5 months (range: 11 days to 4 years and 9 months). The median postoperative follow-up period was 8 months (range: 1-52 months). At the last follow-up, only two patient (7.4%) had residual pulmonary hypertension, and four patient (14.8%) developed anastomotic site stenosis of the reconstructed right pulmonary artery. The mean blood flow velocity in the reconstructed right pulmonary artery was 2.1 ± 0.7 m·s-1. Conclusion：UARPA is frequently associated with atrial septal defect (ASD), patent foramen ovale (PFO) or patent ductus arteriosus (PDA) and is prone to secondary pulmonary hypertension. Pulmonary artery reconstruction surgery demonstrates favorable outcomes, with a low incidence of postoperative complications. Transthoracic echocardiography (TTE) plays a crucial role in the diagnosis and postoperative assessment of UARPA.

Key words: Unilateral absence of right pulmonary artery, Echocardiography, Children