A<unk>  is a cardiac shunt which allows, or is designed to cause, blood to flow from the<unk>  heart to the left heart.  This terminology is used both for the abnormal state in humans and for normal physiological shunts in reptiles. A<unk>  occurs when there is an opening or passage between the atria, ventricles, and/or great vessels. For it to be considered a<unk>  to left shunt, the<unk>  heart pressure has to be higher than the left heart pressure and/or the shunt has a one-way valvular opening.
Right-to-left shunt
Left-to-right shunt
Cardiac shunt
Ventilation-perfusion mismatch
Diaphragmatic breathing
Ventricular reduction
Alveolar-arterial gradient
Hypoxic pulmonary vasoconstriction