
Keywords: نرخ تنش سیستولیک; Cardiac function; Prematurity; Strain imaging; Echocardiography; 2D; Two-dimensional; BPD; Bronchopulmonary dysplasia; CA; Corrected age; FWLS; Free wall longitudinal strain; FWLSRs; Free wall longitudinal systolic strain rate; GLS; Global longitudinal st