The answer is left to right shunt
Ductus arteriosus is a vessel that connect the pulmonary artery with the aorta. Normally, ductus arteriosus will be closed to prevent backflow. Patent ductus arteriosus happens when it doesn't closed.
Since aorta pressure is higher than pulmonary, left to right shunt will be happens. The blood that flow to the lungs will be increased while blood flow to the systemic decreased.