Irreversible pulmonary hypertension is least likely in _____

Irreversible pulmonary hypertension is least likely in _____

• A. Ventricular septal defect
• B. Atrial septal defect
• C. Persistent truncus arteriosus
• D. Tetralogy of Fallot

Answer: (B)

The key idea is that irreversible pulmonary hypertension (Eisenmenger syndrome) develops from long-standing high flow through the pulmonary vessels caused by a left-to-right shunt, leading to progressive vascular remodeling and increased pulmonary resistance. Defects that produce a large, persistent left-to-right shunt deliver substantial pulmonary blood flow, so they are more likely to push the pulmonary vasculature toward irreversible changes. A large ventricular septal defect and a defect like persistent truncus arteriosus fit this pattern, making progression to irreversible pulmonary hypertension more probable. Tetralogy of Fallot, by contrast, often limits pulmonary blood flow because of right ventricular outflow tract obstruction, so the lungs are exposed to less high-pressure flow, reducing the risk of developing irreversible pulmonary hypertension compared with large left-to-right shunt lesions. An atrial septal defect typically causes a slower, more gradual shunt with less sustained high pulmonary flow, so the chance of irreversible pulmonary hypertension is the lowest among these options.

The key idea is that irreversible pulmonary hypertension (Eisenmenger syndrome) develops from long-standing high flow through the pulmonary vessels caused by a left-to-right shunt, leading to progressive vascular remodeling and increased pulmonary resistance.

Defects that produce a large, persistent left-to-right shunt deliver substantial pulmonary blood flow, so they are more likely to push the pulmonary vasculature toward irreversible changes. A large ventricular septal defect and a defect like persistent truncus arteriosus fit this pattern, making progression to irreversible pulmonary hypertension more probable.

Tetralogy of Fallot, by contrast, often limits pulmonary blood flow because of right ventricular outflow tract obstruction, so the lungs are exposed to less high-pressure flow, reducing the risk of developing irreversible pulmonary hypertension compared with large left-to-right shunt lesions.

An atrial septal defect typically causes a slower, more gradual shunt with less sustained high pulmonary flow, so the chance of irreversible pulmonary hypertension is the lowest among these options.