What condition is characterized by a right-to-left shunt?

A right-to-left shunt refers to an abnormal connection between two sides of the heart or blood vessels, allowing deoxygenated blood to bypass the lungs and enter systemic circulation without being oxygenated. This condition is most commonly associated with congenital heart disease, where structural abnormalities in the heart lead to such shunting.

In congenital heart disease, various defects can cause right-to-left shunting, including tetralogy of Fallot, transposition of the great vessels, or atrial septal defects. These structural issues can result in cyanosis, as the body receives a mixture of oxygenated and deoxygenated blood, leading to systemic hypoxia.

The other options do not typically involve right-to-left shunting. Asthma is primarily related to airway obstruction and does not involve a shunt mechanism. Chronic bronchitis is a complication of chronic obstructive pulmonary disease, characterized by airflow limitation due to airway inflammation and mucus production, rather than shunting. Acute respiratory distress syndrome (ARDS) involves acute lung injury resulting in impaired gas exchange, but it also does not involve shunting in the traditional sense, as ARDS affects the lungs’ ability to oxygenate blood rather than redirecting blood flow away from the lungs.

Thus, congenital heart disease is