Prominent Pulmonary Artery
Alexander J. Towbin, MD
DIFFERENTIAL DIAGNOSIS
Common
Pulmonary Hypertension (PH)
Left-to-Right Shunts
Less Common
Pulmonary Thromboembolism
Pulmonary Stenosis
Rare but Important
Absent Pulmonary Valve
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
Underlying causes: Pulmonary hypertension or ↑ pulmonary blood flow
Helpful Clues for Common Diagnoses
Pulmonary Hypertension (PH)
In neonatal period, persistent PH of newborn is most common cause of PH
Associated with neonatal respiratory conditions that result in elevated pulmonary vascular resistance
Causes of PH in children: Congenital heart defects (CHD) and pulmonary disease
Occurs in CHD when pulmonary blood flow or vascular resistance is increased
Main pulmonary artery is larger than aorta
Left-to-Right Shunts
Any CHD with significant shunt → PH
↑ blood flow to pulmonary bed
Over time, smooth muscle hypertrophy of vascular wall
PH eventually progressive, irreversible
Eisenmenger syndrome: When pulmonary pressure is greater than systemic vascular resistance and shunt reverses
Cyanosis in Eisenmenger syndrome
Helpful Clues for Less Common Diagnoses
Pulmonary Thromboembolism
Pulmonary artery obstruction caused by embolism or thrombus
Uncommon in children
Risk factors: Malignancy, CHD, central venous line, lupus, vascular malformations, or renal disease
Central venous lines are most common risk factor for thrombus in children
30-60% have deep vein thrombosis
Chronic pulmonary embolism → right heart failure and PH
Pulmonary Stenosis
Types: Valvular, subvalvular, supravalvular, or in branch pulmonary arteries
Valvular stenosis is most common
7-9% of all CHD
CXR: Dilated main pulmonary artery
Helpful Clues for Rare Diagnoses
Absent Pulmonary Valve
Characterized by narrowed pulmonic annulus and rudimentary cusps, pulmonary artery dilation, and VSD
Constellation of findings, i.e., tetralogy of Fallot with absent pulmonary valve
Often associated with VSD
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