What condition is characterized by cyanosis and dyspnea associated with right-to-left shunting?

The condition characterized by cyanosis and dyspnea associated with right-to-left shunting is Eisenmenger syndrome. This syndrome develops as a long-term complication of congenital heart defects that initially cause left-to-right shunting of blood, such as ventricular septal defects or atrial septal defects. Over time, increased blood flow to the lungs leads to pulmonary vascular remodeling and pulmonary hypertension.

As the pulmonary vascular resistance rises, it eventually exceeds systemic vascular resistance, resulting in a reversal of shunt direction. This causes deoxygenated blood from the right heart to flow directly into the systemic circulation, leading to cyanosis, or a bluish discoloration of the skin due to a lack of oxygen in the blood. Patients often experience dyspnea as a result of inadequate oxygenation.

In contrast, patent ductus arteriosus typically causes left-to-right shunting and does not initially lead to cyanosis or dyspnea unless it causes significant heart failure or is associated with other anomalies that lead to right-to-left shunting. Valvular heart disease primarily affects blood flow through the heart valves and is not defined by a right-to-left shunt. Truncus arteriosus is a congenital heart defect where a single vessel emerges from the heart,