Study of Pulmonary Artery Banding for the Improvement of Left Ventricular Function in Pediatric Heart Failure

The goal of this observational study is to learn about the safety and effectiveness of pulmonary artery banding(PAB) therapy in pediatric heart failure(PHF) patients. The main questions it aims to answer are: * Can PAB therapy improve left ventricular(LV) function in PHF patients especially refractory PHF. * Can the complications caused by the PAB therapy be clinically acceptable? Participants underwent PAB therapy will be required to underwent echocardiography, electrocardiograms, complete blood counts, biochemical tests, and measurements of N-terminal pro-brain natriuretic peptide (NT-proBNP) follow-up before the initiation of PAB and at 1 month, 3 months, and 6 months after PAB surgery. Researchers will compare the LV function 6 months after PAB suergey and the preoperative ones to see if there is improvement.