Patent ductus arteriosus (PDA) is a common cardiac problem in neonates and infants, but determination of its hemodynamic significance can be challenging. We hypothesized that combined left (LA) and right atrial (RA) volumes physiologically best reflect hemodynamically significant patent ductus arteriosus (HSPDA), and utilized two-dimensional echocardiography (2DE) derived atrial volumes to test this hypothesis.