What is the chest x-ray finding in a L-R shunt?

Differentiate pulmonary arterial from pulmonary venous congestion.

Question No.4

X-ray finding in Left to Right Shunt

• ↑ pulmonary vasculature- increase in the caliber and prominence of both upper and lower lobe blood vessels centrally, in midlung and in the periphery.

• Engorged hilar arteries• Right descending pulmonary artery > 1.1cm• Specific cardiac chamber enlargement

ASD VSD PDA PAPVR

CARDIAC SIZE ↑ ↑ ↑ ↑

Pulmonary Vascularity

↑ ↑ ↑ ↑

Main Pulmo Artery Segment

Prominent Prominent Prominent Prominent

LV Normal Enlarged Enlarged Normal

LA Normal Enlarged Enlarged Normal

RV Enlarged Normal Normal Enlarged

RA Enlarged Normal Normal Enlarged

Aorta Small Small Enlarged Small

Charactistic feature

Absent LAE Absent LAE Enlarged Aorta Schimitar Sign

Pulmonary Arterial Congestion

Pulmonary Venous Congestion

•Active congestion•Pulmonary arterial hypertension•Constricted arterial vessels •↓pulmonary vasculature on CXR findings•Dilated hilar trunks•Seen in ASD, VSD, PDA

•Passive congestion•Pulmonary venous hypertension•↑ prominence and thickening of upper lobe vessels•↓ prominence of lower lobed vessels•Hazy hilar vessels present•Roentgen features of Kerley A, B, C lines•Kerley B Lines= pulmonary venous pressure is at 17- 20 mmHg•Pulmonary edema= > 25 mmHg•Seen in left sided obstruction such as mitral or aortic valve defects ( regurgitation and stenosis)