Pulmonary intravascular ultrasound in infants and children with congenital heart disease.

A three-layered appearance of the pulmonary arterial wall has only been described by intravascular ultrasound in adults or autopsy studies of patients with pulmonary hypertension. Thus, pulmonary intravascular ultrasound was performed in 11 patients during heart catheterization to test the hypothesis that distinct layers of peripheral pulmonary arteries can be imaged in infants and children with congenital heart disease. A 3.5 Fr 30 MHz ultrasound catheter was used to image proximal pulmonary arteries with an internal diameter of 3 to 6 mm and distal pulmonary arteries with an internal diameter of 1.5 to 2 mm. Three layers were identified in the proximal arteries of 10 patients but could not be identified in the distal arteries of any patient. There was a significant linear correlation between the indexed dimension of the medial echolucent vascular wall layer and pulmonary vascular resistance. We conclude that intravascular ultrasound can identify vascular changes consistent with medial hypertrophy in the branch pulmonary arteries of young patients with corresponding degrees of pulmonary hypertension.