There are likewise two pulmonary veins, entering the left atrium by one orifice.
The blood arrives back to the left atrium of the heart via the pulmonary veins.
Chronic coughing is a common presentation due to the large left atrium pressing on the airways.
This forces blood into the left atrium right atrium left ventricle right ventricle which then contracts.
This abnormal opening is called an atrial septal defect and causes blood from the left atrium to flow (or "shunt") across the hole into the right atrium.