Pulmonary diffusion defect

A pulmonary shunt refers to the passage of deoxygenated blood from the right side of the heart to the left without participation in gas exchange in the pulmonary capillaries. It is a pathological condition that results when the alveoli of the lungs are perfused with blood as normal, but ventilation (the supply of air) fails to supply the perfused region. [Source: Wikipedia ]

May Cause