Structural composition of central pulmonary arteries. Growth potential after surgical shunts

Failure to achieve adequate pulmonary artery growth in patients with cyanotic congenital heart disease is a major obstacle to surgical correction. To assess whether differences in structural composition of central pulmonary arteries influence their growth potential after surgically created shunts, we obtained full-thickness biopsy specimens from the hilar pulmonary arteries of eight patients with pulmonary atresia or tetralogy of Fallot undergoing modified Blalock-Taussig shunts under 1 year of age. Tissue was processed for electron microscopic studies and a morphometric assessment was made of the volume proportions of smooth muscle, collagen, ground substance, and elastin. Initial pulmonary artery size was determined angiographically during the diagnostic cardiac catheterization. Pulmonary artery size was determined by cross-sectional echocardiograms 7 to 27 months later (mean 19 months). Pulmonary artery growth did not correlate with the interval between examinations but did correlate with the volume proportion of elastin (r = 0.73, standard error of the estimate = 1.45, p less than 0.05). Thus the structural composition of pulmonary arteries may influence their potential for growth after surgical shunts. In particular, an inadequate proportion of elastin may be a hindrance to growth.