In Utero Placement of Aortopulmonary Shunts

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Abstract
Background The development of pulmonary hypertension and its associated increased vascular reactivity is a common accompaniment of congenital heart disease with increased pulmonary blood flow. Although the morphology of the pulmonary vascular changes is well described, the mechanisms of vascular remodeling and increased reactivity remain incompletely understood. Methods and Results To elucidate these mechanisms, we established an accurate and reliable experimental model of pulmonary hypertension with increased pulmonary blood flow. An aortopulmonary shunt was created with an 8.0-mm expanded polytetrafluoroethylene vascular graft in 11 late-gestation fetal lambs. At 1 month of age, shunted lambs had a pulmonary–to–systemic blood flow ratio of 2.2±1.2. Compared with 11 age-matched control lambs, mean pulmonary arterial pressure (44.8±11.7 versus 16.2±2.9 mm Hg) and the ratio of pulmonary to systemic arterial pressure were significantly increased (P<.05). Pulmonary vascular resistance was not significantly i...