The malfunction of the heart in which a hole is formed due to a disconnection between two blood vessels. This is known as APW or aortopulmonary window. When the connection between the largest artery and pulmonary arteries gets disrupted and the pattern of the blood flow gets diverted from the normal circulatory system, it is called left-to-right shunt. https://healthcheckbox.com/cardiology/aortopulmonary-window/