How is pulmonary arterial blood flow affected by pulmonary venous obstruction in children? A phase-contrast magnetic resonance study.
BACKGROUND
Hemodynamic changes within a stenosed pulmonary vein might not reflect the severity of the obstruction if redistribution of pulmonary artery flow occurs.


OBJECTIVE
The purpose was to investigate flow changes in branch pulmonary arteries in the presence of pulmonary vein stenosis.


METHODS
Twelve children (age range 3-180 months) who had undergone MRI for pulmonary vein stenosis were identified. The severity of vein stenosis was assessed from percentage diameter reduction. Pulmonary artery flow distribution was correlated with the severity of pulmonary vein stenosis. Nine of the patients had unilateral stenosis; three had bilateral involvement.


RESULTS
Unilateral vein stenosis was associated with diastolic reversal in the ipsilateral branch pulmonary artery (mean flow reversal 12.3%, range 2.4-42%) and continuous diastolic forward flow in the contralateral pulmonary artery in seven of nine patients. Severe stenosis was associated with decreased systolic flow to the ipsilateral lung. The ratio of net forward flow through pulmonary arteries correlated well with the cross-sectional area ratio of pulmonary arteries (r=0.75, P=0.006).


CONCLUSIONS
Severe pulmonary vein obstruction results in redistribution of pulmonary arterial flow. When investigating pulmonary vein stenosis by MR, an evaluation of the pulmonary arterial system should be included to assess the functional importance of an obstruction.
Roman
Kevin S
KS
Diagnostic Imaging and Radiology, Hospital for Sick Children, Toronto, ON, Canada. kevin.roman@sickkids.ca
Kellenberger
Christian J
CJ
Macgowan
Christopher K
CK
Coles
John
J
Redington
Andrew N
AN
Benson
Lee N
LN
Yoo
Shi-Joon
SJ
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007223:Infant; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D015588:Observer Variation; D011668:Pulmonary Veno-Occlusive Disease / Q000175:diagnosis*; D012189:Retrospective Studies; D018709:Statistics, Nonparametric